Physics

Isotopes Any of two or more forms of a chemical element, having the same number of protons in the nucleus, but having different numbers of neutrons are called isotopes. Some isotopes are unstable, especially those with a lot of neutrons compared to the number of protons in the nucleus. These isotopes tend to eject some particles, in the form of radiation, until a stable nucleus is produced; this is called the radioactive decay. Four isotopes as well as their uses are mentioned subsequently.

Americium: Americium is a silvery metal, which corrodes slowly in air and is soluble in acid. It has the isotopes: Am-243, Am-242 and Am-241, with a half-life of 432 years, which was the first isotope to be isolated. The isotope Am-241 decays by emitting alpha particles and intense gamma radiation to become neptunium-237. Americium (in combination with beryllium) is also used as a neutron source in non-destructive testing of machinery and equipment, and as a thickness gauge in the glass industry.

However, its most common application is as an ionization source in smoke detectors, and most of the several kilograms of americium made each year are used in this way. One gram of americium oxide provides enough active material for more than three million household smoke detectors. Krypton: Krypton 85 (Kr-85) is a radioisotope of krypton. It is a radioactive gas found in the atmosphere and produced by nuclear explosions, nuclear power plants, volcanoes and earthquakes. Krypton-85 is odorless, colorless and tasteless and emits low-level radiation levels of both gamma and beta rays.

Krypton-85 is usually produced in gas mixtures with argon or xenon to improve the ionization in light bulbs by reducing their starting voltage. It also is used in plasma displays, spark gaps and for leak detection. Strontium: Strontium-90 is a radioactive isotope, with a half-life of 28. 8 years. Sr-90 finds extensive use in medicine and industry, as a radioactive source for superficial radiotherapy of some cancers. Controlled amounts of this isotope can be used in treatment of bone cancer. As the radioactive decay of strontium-90 generates significant amount of heat, it is used as a heat ource in radioisotope thermoelectric generators, this is a device where heat released by the decay of a radioactive material is converted into electricity. It is also used as a radioactive tracer in medicine and agriculture. Thorium: Thorium-230 is a radioactive isotope of thorium, which can be used to date corals and determine ocean current flux. Ionium was a name given early in the study of radioactive elements to the Th-230 isotope produced in the decay chain of U-238 before it was realized that ionium and thorium are chemically identical. The symbol Io was used for this supposed element.

Vibration is a broad capable country that has continued to pull research over the old ages because of its import in about every aspect of daily life. From aircraft patterning to constructing design in temblor prone parts of the universe ; from plus status monitoring in assorted industrial workss to wheel reconciliation and alliance at the local auto garage, an application of the cognition of quiver rules can be observed.

The quiver of an object can merely be referred to as the oscillating motion of that object about a average equilibrium place. The gesture is brought approximately by the application of some force or excitement. Common illustrations of this phenomenon include the gesture of plucked guitar strings, the gesture of tuning forks, and the shaking felt at the station floor when a train base on ballss, the agitating observed on the route when a heavy truck base on ballss or the rattle of the route workers ‘ impact cock. Some quiver nevertheless is non every bit pronounced as the illustrations given. For case houses and Bridgess vibrate every bit good. Normally, these quivers can non be detected by simply looking. When the excitement is big plenty, the vibrational gesture can be seen and this would likely ensue in the prostration of the construction.

From the foregoing, it can be seen that some quiver is utile while some is destructive. The failure or devastation brought about by quiver is non an immediate

• Vibration finally leads to a fatigue failure and this should be of involvement to the operators and upholders of works equipment.

For the care applied scientist or plus direction practician, these facts about quiver can be translated to intelligent and informed determinations for industrial workss. With legion different devices, quiver degrees on works equipment can be detected, measured and recorded. It is possible to analyze the informations collected to find the status of an plus and even predict an at hand failure. All revolving or stationary works equipment have acceptable quiver degrees stipulated by criterions such as the International Organization for Standardization ( ISO ) Codes or developed in-house by Vibration Monitoring Engineers. A divergence from the acceptable quiver degrees is an indicant of the oncoming of impairment which is unwanted. This cognition gives insight into the existent status of a piece of equipment, eliminates guessing and enables the care applied scientist to be after a fitting response to the plus ‘s impairment. Such control and planning can take to a immense economy in care costs, prevent unneeded downtime, better safety and public presentation for any plus.

Furthermore, quiver monitoring and analysis incorporates some advanced techniques for the find of the root cause of frequent machinery failures. Using these techniques can intend the difference between changeless dislocations and good plus handiness.

It is the aim of this study to supply a clear cut proposal as to how to work out the job of the frequent failures of the Yoho High Pressure ( H.P. ) Flare Scrubber Pumps by the application of these advanced quiver analysis techniques and besides supply a method for supervising the status of the pump to pre-empt any impairment that can jump surprises. This will guarantee a decrease in present care costs and relieve the work load of care forces whose clip is tied up with the attention of these pumps.

Case Study and job Description

The Yoho H.P. Flare Scrubber pumps are perpendicular, turbine, submerged pumps that transfer cured liquids from the Flare Scrubber vas to the chief petroleum oil production heading on the Yoho offshore oil and gas installing. The pumps are submerged in barrels that receive provender from the H.P. scrubber vas by gravitation. The cured liquid is a mixture of H2O and light petroleum oil. There are three pumps on skid and these pumps are critical to works operations. One pumps runs at a clip and an extra pump or the other two pumps can be put in service, if the demand arise due to an increasing degree of liquid in the H.P. Flare Scrubber. In the event of an outage of all three pumps, the works could lose production to the melody of one hundred 1000 barrels of rough oil per twenty-four hours ( 4100 barrels/hour ) .

The pumps were commissioned in 2006 at works start-up and hold had legion failures since. They have proven undependable and soon a contractor ‘s pumps ( which are portable and of a different design ) , are relied upon to execute their map. There have been occasions when all three pumps are in a province of disrepair.

These pumps normally run swimmingly for a piece and so go noisy, vibrate and eventually neglect. After a pump fails, it is taken out of the hole, sent to the shore-base for fix, sent back to the platform for reinstallation and so reinstalled. Probes of the legion failure instances reveal that the pump bearings, riser line drives and bushings have worn out given room for shaft drama, impeller harm and mechanical seal failure. Installation, fix and rebuild processs have been scrutinized and checked for quality. This has non yielded any dividends nevertheless, as the pumps maintain neglecting after two or three months in service.

The length of the pumps makes it hard for remotion and installing and as such care practicians, works operators and works direction have been invariably distressed by the frequent failure of these pumps.

Pump Specification

• Manufacturer: ITT-Gould
• Head shaft Length: 129 Inchs
• Head shaft Diameter: 1 Inch
• Seal Method: Mechanical Sealing wax
• Drive: 40 HP Electric Motor
• Differential Pressure: 200 Pounds per square inch
• Capacity: 180 Gallons per Minute
• Revolutions per minute: 3000
• Impeller: 5 Weathervanes, Enclosed
• Failure and Maintenance History

The tabular array below shows the failures and some care activities performed on the three H.P. Flare Scrubber Pumps over a biennial period. The rows 69, 71, 72, 90,91,97,98,102,103 and 110 show times when none of the three pumps were operational. The cost of this inaccessibility of the pumps is multiplex. It ranges from the loss of production of about one hundred 1000 barrels of rough oil per twenty-four hours, to punishments for non-compliance with environmental ordinances and most significantly, safety.

Literature Review

Graham and Nurcombe ( 2003 ) , observed that many perpendicular submergible pump failures happen instead out of the blue, without due warning and rough economic climes and competition has become an inducement for equipment operators to want to acquire the best service out of their equipment. This translates to higher life anticipation with works equipment and as such status supervising engineerings such as Vibration, Lubricant and Exhaust gas analyses have become really popular to forestall unwanted and unplanned machinery outages. Of the afore-mentioned techniques, Vibration analysis they say, is likely the most of import because of its proved efficaciousness and global credence in many industries.

In a instance history of submergible pumps at Saudi Aramco, they highlighted the demand to cognize the status of the pump internals which were submerged in liquid and are normally without status monitoring. ISO codes specify that bearings be monitored but this is non straight done for submerged pumps because the bearings are usually unaccessible. Alternatively, ISO allows measurings to be taken from the accessible parts of the machine i.e. from the Electric motor and the downside of this is that plentifulness of quiver information gets losing or attenuated. A batch of the mistakes associated with perpendicular submergible pumps nevertheless arise from those unaccessible places e.g. cavitation, flow induced quiver etc. , and as such supervising the status of the submersed parts straight provides a valuable beginning of information for predictive and diagnostic steps that can do large cost nest eggs for equipment operators.

They have developed and tested transducers and quiver monitoring equipment which can be used to straight acquire information from the submerged pump parts.

It is non plenty merely to supervise the quiver status of these pumps nevertheless. The job at manus is that of the frequent failures of the H.P. Flare Scrubber pumps from the very clip they were commissioned. Installing the submergible quiver monitoring devices would decidedly assist to foretell the failures but would make nil to place the implicit in cause of the frequent failures. So, the failures might be predicted but would go on often however. The root-cause of these failures demands to be identified so that a permanent solution can be developed. Vibration analysis besides makes this possible.

Sinha ( 2008 ) shows that site installing of machines has effects on their quiver and dynamic features, even when they are good designed. He points to the fact that many freshly installed machines vibrate severely and neglect often merely as has been described in the debut and in the care history of the H.P. Flare Scrubber pumps. Hence it is of import to decide any machine installing jobs if equipment handiness is desired. A quiver analysis and dynamic word picture technique known as Modal Testing can be used to uncover the natural frequences of the machine installing assembly and the operating velocity checked to see if near to any of the natural frequences. Operating machines at velocities at or shut to structural natural frequences brings about resonance which is seen as inordinate quiver. This trial makes it possible to place the right places on the construction to use stiffening in order to cut down quiver by modifying the structural natural frequences. He gave some illustrations were these had been done successfully to extinguish frequent machinery failures.

DeMatteo ( 2001 ) presents a instance survey of how the quiver analysis methods of Modal Testing and Operating Deflection Shape have been used to work out the job of inordinate quiver on perpendicular pumps which are similar to the H.P. Flare Scrubber pumps.

A common yet enfeebling mistake for these pumps is cavitation. A mentioned earlier, it occurs at the submersed parts of this pump where there is no status monitoring as of the present. Cavitation is a phenomenon that takes topographic point in these kinds of pumps when the impact of a fall ining vapor of the fluid been pumped causes harm to the impellers and other pump internals. Vapour-bubbles can be formed within the wired fluid at low force per unit area pump internals as a consequence or restricted suction, fluctuating liquid degrees of the H.P. Flare Scrubber vas etc. When these bubbles move on to higher force per unit area countries within the pump, they collapse and cause harm to the pump. Wilcoxon Research says that, “ The prostration of the bubbles is a violent procedure that creates an impacting action inside the pump. This impact will excite high frequence resonances in the pump construction. ” For this ground, they advocate the usage of quiver detectors in pumps. Cernetic ( 2009 ) says in the same vena, that quiver signals should be used to observe cavitation at the early phases of development since this phenomenon causes pump harm and a decrease in efficiency.

From the foregoing, the instance for forestalling failures is being made and the demand for Condition Based Maintenance ( CBM ) emphasised. Prickett and Eavery ( 1991 ) compared preventative care and Breakdown care with CBM. CBM is shown to be cheaper and as such is required for the H.P. Flare Scrubbers if concern profitableness and equipment handiness are desired.

Overview of Proposed Vibration Monitoring and Analysis Based Solution to Frequent Failures

First and first, it must be ascertained that the site installing of the three pumps is non doing any quiver jobs. The Vibration analysis techniques of Modal Testing and Operating Deflection Shape are proposed for usage to find the root-cause of the frequent failures. Modal proving on the one manus would demo structural natural frequences, node points and manner forms for the three pumps. The manner form is the warp of the construction at any natural frequence. This information would assist to find: if operating velocity is perilously close to the structural natural frequences, the dynamic feature of the construction and the points of least or no warp on the construction ( nodes ) – where supports or stiffening may be added in order to relieve quiver degrees. The Impact cock method shall be used to transport this trial out, in situ.

The Operating Deflection Shape ( ODS ) on the other manus, would as the name implies show the warp of each pump construction at the operating frequence of 50Hz ( 3000RPM ) . In other words, the ODS would demo the consequence of the operating velocity on assorted parts of the construction and it can be seen if points on the construction vibrate in stage or non. Should parts of a construction non travel in stage with the other parts, destructive burden can happen which can give rise to frequent failures.

Transporting out these trials as mentioned above would place jobs with the installing. Solving the installing jobs would extinguish the frequent failures. The solution as mentioned earlier, normally involves the application of supports in identified places or the stiffening of bing supports.

After the installing jobs are taken attention of, it is proposed that for good mounted quiver detectors are put in topographic point. For the open parts of the pump assembly i.e. the electric motor, it is proposed that two accelerometers be mounted at each of the antifriction bearing lodging countries. The accelerometers would be stud mounted at each bearing lodging at right angles apart. Having these accelerometers installed in add-on to the analysis of the generated signals would do it possible to observe bearing mistakes at their incipient phases, such that something could be done to forestall a more dearly-won harm to the whole pump assembly.

As for the submersed parts of the pump, i.e. the journal bearings, the shaft, the impeller/bowl assembly, the Bently Nevada designed submergible propinquity investigations are proposed for usage to supervise the quiver and give diagnostic and prognostic capablenesss for such mistakes as cavitation, impeller harm, weariness shaft cleft, instability etc. , which are the common mistakes of machinery such as these and can merely be detected by submersed detectors. Understanding what goes on in the pump hole is critical to maintaining the pump healthy. For case cavitation can be detected on clip with these investigations, procedure conditions changed and the dependability of the pumps maintained. The quiver information collected by these detectors would be analysed and used to do quality determinations sing the needed care responses. Analysis techniques would include frequence spectrum analysis, envelope analysis, polar secret plans, orbit secret plans etc.

This three prong attack is strongly believed to extinguish the frequent failures, cut down the overall care costs and assist in guaranting the handiness of the three H.P. Flare Scrubber Pumps.

The techniques shall be expounded in more item within this study and all the necessary tools and quiver signal processing methods shall be specified.

In-Situ Modal Testing for the Pumps

This quiver trial is to uncover any jobs with the installing of the pumps which might be responsible for the frequent failures experienced within the past few old ages. In this trial, the natural frequences, manner form and nodes will be determined for each pump construction.

An instrumented cock would be used to provide impact or energy to each construction at a known frequence and responses measured. When there is resonance, elaboration would be seen in the response spectrum. A Frequency Response Function ( FRF ) is obtained utilizing the force and the response spectra. The response can be represented as:

FRF= = A + J B

Where A= Real Part, B= Imaginary Part and Phase =

At Resonance, the exciting frequence from impact cock = Natural Frequency of Pump Structure.

A 0, B gives the Mode Shape, and Phase 90A°

The computations are performed and graphs displayed by the FFT ( Fast Fourier Transformation ) Analyzer as shown below.

Fig. 3. Time sphere and frequence sphere signals. ( Beginning: M14 Lecture Notes, 2010, MSc Maintenance Engineering and Asset Management, University of Manchester )

The FRF shows frequence extremums which may or may non be structural natural frequences. However, for the structural natural frequences, the relationships shown supra would all use. The existent portion of the curve ( A ) would go through through nothing and the stage would alter by 90A° . The fanciful portion of the FRF gives the manner form.

So, the needed equipment for the unmoved average testing of the pump constructions are as follows:

Some accelerometers positioned along points on a pump construction ( accelerometers can be secured by magnetic agencies )

An instrumented cock

An FFT Analyzer

Cable connexions for cock and accelerometers to analyzer

Post Processing Software

From the attendant manner forms and ascertained natural frequences, penetration can be obtained as to the exact places for stiffening application or mass remotion in order to alter the natural frequences. Experience has shown that resonance in these kind of instances is due to the intimacy of the operating velocity ( runing frequence or 1x ) or multiples thereof, to one or more structural natural frequences. For the pump described in fig.7. above, the job was solved welding a thick home base to the stool in order to stiffen it and by put ining extra u-bolts on the discharge line.

Operating Deflection Shape

The Operating Deflection Shape ( ODS ) merely shows how much the pump construction is traveling at a peculiar frequence ( most significantly, the normal runing velocity ) and how much difference there is in stage between different points of the pump construction as it operates.

The set-up is merely as was used for the average testing. The difference nevertheless, is that the instrumented cock is non used to excite the construction. Alternatively the machine would be run at its normal operating velocity and quiver informations collected from the accelerometers is fed to the multi-channel analyser. The end product from the analyser is so fed into the computing machine which would hold installed specializer package for ODS show. The show would demo the existent quiver form of the construction. It would be clearly seen, if the pump construction is flexing, if parts are traveling out of stage with one another etc. It would be seen if any status exists which contributes to frequent failures.

It is proposed that both Modal Testing and ODS analysis be carried out by contractors who are specializers in the country of survey and have a proved path record of success.

The accelerometers would be used to mensurate the quiver degrees of the anti-friction bearings on the pumps ‘ electric motors while the submersed propinquity investigations would mensurate shaft quiver, within the impeller shell and intermediate columns. All the transducer information would be collected by the 1900/65 proctor for each equipment. The proctors are designed for uninterrupted monitoring and readouts from them can be checked from clip to clip by dedicated forces or works operators.

Besides, these proctors have the capableness of being tied into bing works control systems such that quiver warning degrees and danger bounds for each pump can be announced in control suites via hearable dismaies or visible radiations when these degrees are breached. Additionally, there is the capableness to configure trips and closures in the instance of high quiver degrees occasioned by mistakes such as cavitation. The proctors can be installed near to the equipment in sheltered enclosures, utilizing a short overseas telegram tally. The System 1 package is capable of advanced quiver analysis through the usage of shows such as Bode Plots, Spectral shows, Polar secret plans, Envelope analysis, etc. It is besides capable of informations acquisition and storage which makes swerving possible. Detailed specifications for the assorted equipment are supplied in the appendix.

Signal Conditioning and Processing

As is good known, the end product from the accelerometers and propinquity investigations are linear and clip sphere signals. These have to be converted to digital end products and frequence sphere signatures for mistake diagnosing to be carried out. This is achieved by the Fast Fourier Transformation ( FFT ) algorithm. Analyzing the frequences shown in a spectrum is indispensable for understanding implicit in machinery mistakes, as certain mistakes have distinguishable frequence features. For case, pump revolving velocity would be shown in the frequence spectrum and mistakes on the shaft could be presented as multiples of revolving frequence. The Bently Nevada 1900/65 proctor and System 1 package facilitate this.

The quiver measuring devices have been chosen carefully to understate the noise and unwanted intervention to measuring signals. The Bently Nevada 1900/65 has the capableness for low base on balls filtering and high base on balls filtering and these can be configured to accommodate user demands. This helps to extinguish the aliasing consequence and other instrument related noise. ( See merchandise specification sheet in appendix for inside informations ) .

There is besides the capableness for envelope analysis by the usage of criterion or enhanced demodulation. This is supported by proctor and analysis package and is peculiarly utile for the early sensing of mistakes on the electric motor anti-friction bearings.

Diagnosis Software Display Plots and Uses

The following show some of the show plots that can be generated by the diagnostic package:

1. Bode
2. Performance map
3. Rotor stator profile
4. Rotor form
5. Hydro air spread
6. Phasor
7. Histogram
8. Octave
9. Casacade/Full Casacade
10. Current values
11. Bar graph
12. Machine train diagram
13. Alarm/System event list
14. Trend / Multivariable tendency
15. Tabular list
16. Time base ( with option for superposition
17. of baseline informations )
18. Orbit / Time base ( with option for
19. superposition of baseline informations )
20. Orbit ( with option for superposition of
21. baseline informations )
22. Shaft mean center line
23. Spectrum / Full spectrum ( with option
24. for superposition of baseline informations )
25. Ten vs. Y
26. Waterfall / Full waterfall
27. Polar/Acceptance part

Of the list above, accents would be placed on the Bode, Polar, Orbit, Shaft mean centreline and Waterfall secret plans. These secret plans can be used during normal and transeunt machine conditions to expose the normally experient mistakes.

The Bode secret plan is really utile in placing the critical velocity ( natural frequence ) of a machine, as it shows the quiver behavior of the said machine during start-up or shut-down ( transeunt conditions ) .

The polar secret plan gives the amplitude of 1X ( machine RPM or runing frequence ) and its stage difference from the mention place. The amplitude and stage behaviors can be interpreted to existent equipment wellness or defect.

The Orbit secret plan hints out how the shaft is revolving within the bearing. This tells how much clearance exists between shaft and bearing wall. This information is priceless as it can be used to find bearing load alterations and the oncoming of bearing wear.

Diagnosis Chart

Mistake

Steady province Characteristic

Transient State Characteristic

Shaft hang-up

• 0.3 X shown in frequence spectrum,
• Funny Orbit secret plan forms and discontinuities thereof.
• Imbalance
• Merely 1X is seen in frequence spectrum, 1X additions with clip and the Phase angle alterations
• Bode Plot remains the same, There is no alteration in critical velocity or stage angle when compared with the healthy status.
• Misalignment ( or Preload in the instance of unstable bearings )
• 1X,2X,3X,4X etc are shown in frequence spectrum, Phase angle remains changeless
• The orbit secret plan will non change with velocity and polar secret plan remains the same.
• Crack
• 1X, 2X, 3X, 4X etc are shown in frequence spectrum and these continually alteration in amplitude. The stage angle alterations every bit good.
• There is amplitude and phase alteration of 1X constituent in the polar secret plan,
• The orbit secret plan alterations from a figure eight form to a cringle incorporating a little cringle.
• Bend
• Merely 1X is seen in frequence spectrum, 1X additions with clip and the Phase angle alterations
• A signal alteration of stage takes topographic point at critical velocity.
• Mechanical Diarrhea
• Presence of 0.3X, 0.5X, 1X,1.5X,2x, 2.5X in frequence spectrum
• Motor Bearing Damage
• Bearing Characteristic Frequencies would be seen in spectrum
• Fluid induced instability
• The presence of 0.45-0.48 X in spectrum when fluid natural frequence is approached by circumferential velocity of fluid, stand foring Oil Whirl.
• The presence of 0.45-0.48 X in spectrum when fluid natural frequence is approached by circumferential velocity of fluid, stand foring Oil Whirl
• Oil Whip consequences when Pump System rotor natural frequence peers fluid ‘s.

Fault Diagnosis Process

The overall quiver degrees measuring would be the first phase of protection for the pumps. The ISO recommends the usage of RMS values of speed for overall quiver measuring. Limits for acceptable quiver would be set and configured into the Bently Nevada 1900/65 proctors in footings of Velocity ( RMS ) . These proctors can denote when the bounds have been breached and this would motivate farther probe and trials. These bounds can be obtained from ISO tabular arraies or decided upon in-house by the care applied scientist. The proctor would demo which peculiar detector or detectors has detected a mistake.

Furthermore, the proctor and diagnosing package proposed are capable of informations acquisition and storage which make it possible for swerving. The tendencies would be observed hebdomadal and when a set quiver bound is approached, the frequence of review is increased and trials such as the 1s mentioned before can be carried out to determine the mistake type, so a fitting care response can be planned.

The mistake diagnosing chart would be used in concurrence with the FMEA diagram, 1900/65 proctor event logs and assorted applicable show secret plans ( frequence spectrum shows, Bode secret plan, Polar secret plan etc ) to corroborate the exact mistake of the pumps. Pump related frequences would be noted such that when they appear in the frequence spectrum, they can easy be identified.

FMEA, Symptoms of identified impairment mechanisms

Potential Failure Mode

Potential Effectss of Failure

Potential Failure Causes

Symptoms of identified impairment mechanisms

1

Antifriction Bearing mistake ( Electric motor )

Bearing Seizure, Misalignment,

Damage to motor shaft, Mechanical seal failure.

Poor lubrication, Resonance

High Frequency Hump seen in Frequency spectrum related to bearing lodging natural frequence

2

Shaft Cracks

Shaft Fracture, Loss of pump action

Resonance, Manufacturing defects

1X, 2X, 3X, 4X etc are shown in frequence spectrum. These addition in amplitude over clip.

3

Cavitation

Impeller Damage, Reduced end product, Pump loss.

Process disturbances, Gas lock in Pump Barrel

Noisy operation, High frequence extremums in spectrum

4

Imbalance

Excessive Vibration, B

Damage to bearings and Impellers, Pump loss.

Wear, Impeller harm

1x constituent in frequence spectrum which increases in amplitude over clip.

5

Journal Bearing Wear

Lateral shaft drama, Shaft harm

Matching misalignment

Noisy operation, Lateral shaft drama,

6

Impeller Damage

Reduced end product, Pump loss, Imbalance,

Improper assembly,

Cavitation, Flow-induced quiver

Blade Passing frequence nowadays in frequence spectrum ( 5X,10X etc )

7

Bent Shaft

Bearing harm, High quiver

Matching misalignment, Resonance

Axial quiver, 1X presence in frequence spectrum

8

Matching Misalignment

Resonance, Damage to pump internals, Mechanical seal failure, Loss of pump.

Improper assembly, Resonance

1X,2X,3X,4X etc are shown in frequence spectrum

9

Shaft hang-up

Damage to pump internals, Mechanical seal failure, Loss of pump.

Matching misalignment

0.3X, 0.5X presence in quiver spectrum secret plan

10

Diarrhea

Damage to pump internals, Mechanical seal failure, Loss of pump.

Resonance, Improper Assembly

The presence of 0.5X, 1X, 1.5X, 2X, 2.5X etc in frequence spectrum

Fig. 19. FMEA tabular array for pump and motor assembly.

Cost and Man-Power Implications of Vibration Monitoring and Analysis Set-up

The monetary values given are estimations based on monetary values obtained from assorted cyberspace shopping web sites. They are non unequivocal as Bently Nevada gives monetary values based on different functionality demands and applications worldwide.

Item

Measure required for all three pumps

Unit Price ( $ )

Price ( $ )

Accelerometer, Bently Nevada 330400

12

500

6000

Monitor, Bently Nevada 1900/65

3

2500

7500

Submersible Proximity investigations, Bently Nevada

12

1000

12000

Tacho Sensor, Bently Nevada

3

300

900

Laptop

1

1000

1000

System 1 Diagnostic Software Licence, Bently Nevada

1

20000

20000

Training for quiver applied scientist ( from bing care administration )

2500

Entire Price $ 49,900

Fig.20. Cost breakdown of needed equipment for for good mounted quiver monitoring and analysis system.

At lease one applied scientist with accomplishments for quiver monitoring and analysis would be required to supervise the whole set-up. He must be trained and competent in the usage of assorted show secret plans, signal processing and conditioning, for mistake designation and sensing.

This cognition can besides be used on other critical works equipment such as the gas turbines and the centrifugal gas compressor.

The dynamic word picture trials are to be contracted out to see service suppliers with the equal hardware and package for real-time life of vibrational gesture. It is estimated that the cost of this service would be circa $ 100,000. This brings the expansive sum of the proposed quiver programme from the frequent pump failures solution to for good installed status monitoring to about $ 150,000.

Benefits and Limits of the proposed Vibration-based Condition Monitoring System

The proposed set-up for monitoring and analyzing the quiver from the pumps has rather a figure of benefits.

From the concern point of position, it is an investing because it can forestall dearly-won failures. The dollar value of the pumps ‘ failure within the biennial period considered in this study easy exceeds $ 1million when fix costs, trim parts, logistics and man-hours expended are considered.

For the care administration, the presence of these vibration-based status monitoring equipment, makes it possible for care to be pro-active instead than reactive. Furthermore, frequent failures are eliminated which give room for better planning and more clip for effectual and efficient care.

The cost of the quiver monitoring and analysis equipment can be seen to be a little monetary value to pay for plus handiness, enhanced productiveness and even safety.

The restriction to the proposed system is the accomplishment, cognition and competency of the applied scientist or applied scientists who are in charge of the set-up. The signals for any mistake status would ever be picked up by the monitoring equipment. The proper and accurate diagnosing of mistakes and subsequent care determinations made are the remit of the applied scientist ( s ) responsible for the vibration-based status monitoring programme. In add-on, quiver monitoring equipment could neglect and necessitate replacing.

Decision

A glimpse through the summarised failure and care history of the H.P. flair scrubber pumps for a two twelvemonth period reveals the sum of resources expended on them and their hapless handiness. Clearly so, something new and different from the old attacks should be attempted.

This proposed system covers all the grounds- from installing jobs check, procedure vagaries that cause cavitation, to common mistakes experienced by revolving machines such as bearing defects and matching misalignments to advert a few.

Besides, the proposed methods are tested and trusted and can lend to nest eggs in care cost, works handiness and safety which are cardinal public presentation indexs for most industrial workss.

Nanoscience includes the survey and creative activity of stuffs, devices, and systems by pull stringsing single atoms and molecules. It describes research where the characteristic dimension of 1 or more planes is less than 100 nanometres i.e. , 0.1 micrometers.

As we know that all manufactured merchandises are made from atoms and the belongingss of those merchandises depend on how atoms are arranged in them.

So if we can rearrange the atoms in: Coal we get diamonds or black lead.

Sand ( adding a few other hint elements ) we get computing machine french friess.

Dirt, H2O and air we can do murphies.

Unlike their larger or “macro ” opposite numbers, nanoparticles frequently display alone belongingss that may be of usage for assorted applications.

Introduction to liquid crystals

The survey of liquid crystals began ( 1888 ) when an Austrian phytologist, Friedrich Reinitzer observed that a stuff known as cholesteryl benzoate had two distinguishable runing points. In his experiments, Reinitzer increased the temperature of a solid sample and watched the crystal alteration into a brumous liquid. As he increased the temperature further, the stuff changed once more into a clear, crystalline liquid. Because of this early work, Reinitzer is credited with detecting a new province of affair – the liquid crystal province.

What are liquid crystals?

There are solids which when heated undergo two crisp stage transmutations one after the other. They foremost fuse aggressively giving turbid liquid and so once more every bit aggressively at higher temperature giving clear liquids.

These alterations are precisely reversed on chilling at the same temperatures. The turbid liquid nevertheless show anisotropy ( i.e. , they have different physical belongingss in different waies ) . Anisotropy is observed peculiarly in their optical behaviour.

Therefore they exhibit dual refractions and intervention forms in polarized visible radiation. True liquids, on the contrary, are isotropous ( i.e. , they have same belongingss in all waies ) .

Since anisotropic belongingss are associated with crystalline province, the turbid liquids are called liquid crystals. And as they are neither solids nor liquids, hence, the term muscular province ( intending intermediate signifier, in Greek ) likely fits the best. But liquid crystal besides continues to be used even in present twenty-four hours literature.

Obviously, an indispensable demand for mesomorphism to happen is that the molecule should be anisotropic in form, like rod or a phonograph record. Industrial Lubricants exist, more or less, in liquid crystalline, i.e. , muscular province. The proteins and fats besides exist or acquire changed into this province before digestion and are therefore easy assimilated into the organic structure. This province is believed to play an of import function in the nutritionary and other procedures.

Note the mean alliance of the molecules for each stage in the undermentioned diagram.

It is sometimes hard to find whether a stuff is in a crystal or liquid crystal province.

Crystalline stuffs demonstrate long scope periodic order in three dimensions.

By definition, an isotropic liquid has no orientational order.

Substances that are non ordered as solids, yet have some grade of alliance are decently called liquid crystals.

There are two basic stages of Liquid Crystals:

Liquid crystals act like polarising filters. The orientationally ordered rod-like molecules in liquid crystals affect the polarisation of the familial visible radiation.

What is Liquid crystal displays?

A procedure of picture show which is based on liquid crystal bed sandwiched between two polarising crystalline glass beds. The crystals that are charged by transistors unfastened and close to let and barricade the transition of visible radiation. In a projection format, visible radiation is passed through the LCD panel, from an internal lamp, onto the screen and each crystal is represented by one pel.

Types of LC displays

There are the undermentioned types of Liquid Crystal Displaies:

• Active matrix liquid crystal show
• Cholesteric liquid crystal show
• Transflective liquid crystal show
• ST liquid crystal show

CRTs work by lighting points of phosphor on the screen by firing a beam of negatrons from the dorsum of the tubing.

At the rear of the tubing an emitter is present. A beam of negatrons is sent towards the screen at the forepart of the tubing, by the emitter. The beam of negatrons is passed through a magnetic field which targets it at specific place on the screen, at the forepart of the tubing. The screen in forepart of the tubing is coated with phosphor which glows when it is struck by negatron beam. The phosphor points are arranged in little groups of ruddy, green and bluish and by uniting these three primary colourss, any colour can be created.

Advantages of CRT

Due to the glowing points being near to the surface of glass, each point is every bit bright from any sing angle.

As each point is self-illuminating, uneven lighting or screening angles would non do colour fluctuations across the surface of the screen.

CRT ‘s don’t endure from the job of “ dead pels ” that consequence Plasma and LCD shows because the procedure of puting down the phosphor points is really simple.

Disadvantages of CRT

As the CRT screens get larger, their glass must acquire thicker to defy the force per unit area of the vacuity inside which would ensue in telecastings weighing 100s of lbs.

The phosphor compounds which really create the seeable visible radiation in the CRT show become less aglow with usage. This is one of the chief grounds for why an old telecasting set expression dim. If the show is systematically used to demo the same image for a long period of clip, the image can acquire “ burned in ” to the screen and it appears as a darkened image whenever the show is turned on.

This is a common issue in instances when the show is connected to a computing machine where the common screen elements such as bill of fares or Windows may stay on the screen for a long period of clip.

While the new sets use a no. of techniques to cut down the happening of burn-in drastically, the overall brightness of the show still diminishes over clip.

CRT shows are limited to size around 45 inches. They are besides deeper than about all other shows because the negatron gun is placed far plenty behind the screen such that the full surface can be hit by it. Earlier the negatron gun had a sweep angle of 90 grades but in the late 1990 ‘s many CRT ‘s started utilizing negatron guns with 100 grades arc, which allowed shorter tubings to be used.

How does liquid crystal display works?

The liquid crystal show works by reflecting a changeless, pure white visible radiation, foremost through a liquid crystal “ shutter ” and so through a coloured filter to make each point ( pel ) on the show. Each pel is really made up of three of these points of ruddy, green, and blue, each.

The liquid crystal “ shutters ” first base on balls the polarising the visible radiation in one way and so base on balls it through a bed of liquid crystal.

The liquid crystals are used to revolve the polarisation of the light passing through them, when the current is applied and the sum of rotary motion is controlled by changing the current.

The visible radiation is so passed through a colour filter for the remotion of other constituents of the white visible radiation, go forthing merely the coveted colourss.

The colored ( and polarized ) visible radiation is so passed through a concluding polarizing filter which is rotated 90 grades with regard to the original polarizing filter. If the visible radiation had non been rotated, so no visible radiation would ‘ve passed through the 2nd polarizing filter and the point would look dark.

If the visible radiation had been to the full rotated, so it would go through through the filter at maximal strength.

Advantages of LCD

The advantages of a liquid crystal show are:

Due to the absence of any big tubing, the LCD is much thinner than a CRT show.

Because it requires a beginning of visible radiation and the lightweight LCD shutters, the liquid crystal show is much lighter than CRT shows.

Although the light beginning is required to run at maximal power over the full surface of the show, LCD ‘s by and large use lesser energy to run than CRT shows. Nowadays LCD shows use LED backlights usage less energy than any other show.

Disadvantages of LCD

The disadvantages of the Liquid crystal show are:

Because of the colour filters and liquid crystals sitting between the spectator and the light beginning, each pel on an LCD show exists in a little “ box ” that prevents visible radiation from shed blooding from one pel to another. The “ walls ” of these boxes block the line-of-sight between the light beginning and the spectator when viewed at an angle which reduces the sensed brightness of that pel. Newer and more expensive shows are utilizing shallower boxes to minimise this issue.

Earlier, LCD shows had been plagued by slow response times because of the liquid crystals taking clip to alter province which consequences in “ blurring ” or “ streaking ” of fast-moving images.

Newer theoretical accounts do non endure from this show “ slowdown ” as much.

LCD shows use a individual visible radiation beginning that eliminates each pel in the show equally. It is really hard to fabricate a visible radiation beginning which is equally illuminated across its full surface.

Inexpensive LCD ‘s frequently have uneven illuming across the show. In add-on, on larger shows, the spectator ‘s angle from the show may change rather a spot from the centre to the borders of the screen. Because of this the pels near the borders appear darker because they are non being viewed head-on.

As the light beginning is ever “ on ” behind every point of the LCD, it is hard to wholly barricade the visible radiation at a given pel and accomplish true black.

The physics concepts that were illustrated in our egg drop project were momentum and energy. In the project, we saw how momentum increases as a normal egg without anything to slow it down would crack. That was because the longer that the egg fell, the more momentum the egg gains. We also saw that by adding resistance during the fall, such as a plastic bag “parachute”, would slow down the egg enough so that It would not crack when It reached Impact with the ground.

The other concept that was discussed was energy. We saw that before the egg Is dropped, It has a potential energy. The potential energy Is the amount of energy that can turn Into hysterical kinetic energy, which can be expended when the egg falls to the ground. The energy can leave the objects from the Impact of the fall (deformation of the object), sound waves, the Impact It has on the floor, or In the surroundings of the egg.

In order for a project to be successful, the project would have to have parts that would help slow the energy that would surely break the egg without a protective barrier. If I were to do this project again, I would probably add more sponges tot the Inside sides of the construction paper basket and add little pen springs on the bottom of he basket. I would add more side sponges because when we did the actual dropping of the egg, I noticed that the whole basket fell to its side when it reached the ground.

By adding more sponge, this would add more cushion to absorb the kinetic energy. I would add the little pen springs on the bottom of the basket so that the whole basket’s impact could be absorbed, not only the egg being protected, but also the sponges. By adding these modifications, the egg may be able to withstand an even higher fall than a two story drop because of the extra cushions that would be able to absorb the energy.

The mechanical properties of materials are determined by performing carefully designed laboratory experiments that replicate as nearly as possible the service conditions. In real life, there are many factors involved in the nature in which loads are applied on a material. The following are some common examples of modes in which loads might be applied: tensile, compressive, and shear. These properties are important In materials selections for mechanical design. Other factors that often complicate the design process Include temperature and time factors.

The topic of this lab is confined to the tensile property of polymers. Figure 1 shows a tensile testing machine similar to the one used in this lab. This test is a destructive method, in which a specimen of a standard shape and dimensions (prepared according to ASTM D 638: standard test method for tensile properties of plastics) is subjected to an axial load. During a typical tensile experiment, a dog-bone shaped specimen Is gripped at Its two ends and Is pulled to elongate at a determined rate to Its breakpoint; a highly ductile polymer may not reach its breakpoint.

The tensile tester seed in this lab is manufactured by Insertion (model 5569). It has a maximum load of 2 or 50 ink and a variable pulling rate. The setup of the experiment could be changed to accommodate different types of mechanical testing, according to the ASTM standard (e. G. Compression test, etc). For analytical purposes, a plot of stress (o) versus strain (E) Is constructed during a tensile test experiment, which can be done automatically on the software provided by the instrument manufacturer. Stress, in the metric system, is usually measured in N/ mm or Pa, such that 1 N/mm = 1 Pa.

From the experiment, the value of stress is lactated by dividing the amount of force (F) applied by the machine in the axial direction by its cross-sectional area (A), which is measured prior to running the experiment. Mathematically, It Is expressed In Equation 1. The strain values, which have no units, can be calculated using Equation 2, where L Is the Instantaneous length of the specimen and LO Is the initial length. (Equation 1) (Equation 2) A typical stress-strain curve would look like Figure 2. The stress-strain curve shown In Figure 2 Is a textbook example of a stress-strain curve.

In reality, not all stress-strain curves perfectly resemble the one shown In Figure 2. This stress-strain curve Is typical for ductile metallic elements. Another thing to take note is that Figure 2 shows an “engineering stress-strain” curve. When a material reaches its ultimate stress strength of the stress-strain curve, its cross-sectional area reduces dramatically, a term known as necking. When the computer software plots the stress-strain curve, it assumes that the cross sectional area stays constant throughout the experiment, even during necking, therefore causing the curve to slope down.

The “true” stress- change in the cross sectional area of the specimen throughout the experiment. Theoretically, even without measuring the cross-sectional area of the specimen during the tensile experiment, the “true” stress-strain curve could still be constructed by assuming that the volume of the material stays the same. Using this concept, both the true stress (UT) and the true strain (ET) could be calculated using Equations 3 and 4, respectively. The derivation of these equations is beyond the scope of this lab report. Consult any standard mechanics textbook to learn more about these equations.

In these equations, LO refers to the initial length of the specimen, L refers o the instantaneous length and o refers to the instantaneous stress. (Equation 3) (Equation 4) Figure 2 also shows that a stress-strain curve is divided into four regions: elastic, yielding, strain hardening (commonly occurs in metallic materials), and necking. The area under the curve represents the amount of energy needed to accomplish each of these “events. ” The total area under the curve (up to the point of fracture) is also known as the modulus of toughness.

This represents the amount of energy needed to break the sample, which could be compared to the impact energy of the sample, determined from impact tests. The area under the linear region of the curve is known as the modulus of resilience. This represents the minimum amount of energy needed to deform the sample. The linear region of the curve of Figure 2, which is called the elastic region (past this region, is called the plastic region), is the region where a material behaves elastically. The material will return to its original shape when a force is released while the material is in its elastic region.

The slope of the curve, which can be calculated using Equation 5, is a constant and is an intrinsic property of material known as the elastic modulus, E. In metric units, it is usually expressed in Pascal (Pa). (Equation 5) Figure 3(a) shows typical stress-strain curves of polymers. The figure shows that materials that are hard and brittle do not deform very much before breaking and have very steep elastic modulo. The mechanical property of polymers generally depends on their degree of crystalline, molecular weights and glass transition temperature, Tug.

Highly crystalline polymeric materials with a Tug above the room temperature are usually brittle, and vice versa. When a semi-crystalline polymer undergoes a tensile test, the amorphous chains, will become aligned. This is usually evident for transparent and translucent materials, which become opaque upon turning crystalline. Figure 3(b) shows a diagram showing the mechanical property of some common polymers. Important! Make sure you wear safety glasses before starting any operation. Your eyes could be hurt by a broken piece of polymer. Also wear gloves to protect against any residue on the machine and samples. . 1 Specimen Preparation The polymer specimens were injection-molded into dog-bone shapes. Their dimensions were determined according to the ASTM D 638 standard mentioned earlier in the introduction. (1) Measure the thickness, width and gage length of polymer samples in mm. These dimensions should be approximately the same for each sample. (2) Also make note of any sample defects (e. G. Impurities, air bubbles, etc. ). The following samples will be tested: 1) Polypropylene (UP), polystyrene (AS), polycyclic acid (polymer), high density polyethylene (HIDE), and Dentally for analysis of mechanical properties. ) Polystyrene: to compare effects of feeding direction on mechanical properties. 3) Polypropylene: to analyze effects of strain rate on mechanical properties. . 2 Bluebill Software Setup 1) Turn on the tensile test machine. The switch is located on the right side of the machine. Also turn on the video extensors. (2)Go to the desktop and double-click on the “Bluebill” icon. (3) On the main page, select Test to start a new sample. Name your test and click Browse to select the folder you would like to save it in. Click next. (4) Choose which method you would like to use.

Create and save a new method if needed. (5) Method set up: Save after any changes are made. General: used for display purposes Specimen: specifies sample dimensions and parameters. A doggone sample is used for tensile testing. Select rectangular, and specify the width, thickness and gauge length of the sample. The gauge length is the distance between the clamps before starting the test. Control: describes the actual test. Select extension for mode of displacement, then specify the rate of extension. Most use 5 mm/min or 50 min/mm, depending on if you want a slow or fast test.

End of Test: identifies the criteria for the end of the test. A large load drop is experienced when sample failure occurs. For this test, when the sample load drops by a certain percentage of the peak load, he machine will stop. Data: specifies if the data is acquired manually or automatically, while the strain tab recognizes whether the strain is measured from the video exterminates or the extension. Results and Graphs: select what data is shown and how it is displayed. (1) Make sure the proper load cell is installed, either 2 ink or 50 ink depending on the load range and sensitivity of the sample.

To switch load cells, make sure the machine is off. Unscrew the bolts and remove using the handle. Make sure to plug the new load cell into the port behind the machine. (2) Calibrate the load cell by licking on the button in the upper right hand corner. Make sure all loads are removed from the load cell and click calibrate. (3) Install the correct type of clamps for the testing. For tensile testing, non or ink samples can be used. Install the clamps using the pins. Also install height brackets if needed. Zero the load once the clamps are installed. 4) Press the up and down arrows on the controller until the clamps are Just touching. Press the reset gauge length button at the top of the screen to zero the position of the clamps. (5) Use the up and down arrows until the clamps are about 100 mm apart. This is a typical gauge length for the dog bone samples. (6) Place the polymer sample between the grips of both the tensile test machine. While holding the sample vertically with one hand, use another hand to turn the handle of the top grip in the closing direction as tightly as possible. The specimen should be gripped such that the two ends of the specimen are covered by the grip, approximately 3 mm away from its gage-length. It is important that the specimens are tightly gripped onto the specimen grips to prevent slipping, which will otherwise result in experimental errors. ) (8) Make sure that the specimen s vertically aligned, if not a torsion’s force, rather than axial force, will result. (9) Turn the bottom handle in the “close” direction as tightly as possible. Visually verify that the sample is gripped symmetrically at its two ends. 10)Zero the extension by pushing zero extension button at the top of the screen. Also zero the load if needed. Wait for a few seconds to let the computer return its value to zero. 2. 4 Tensile Test (1) Enter geometry of the sample before starting. (2) Click on the Start button. Both the upper and bottom grips will start moving in opposite directions according to the specified pulling rate. Observe the experiment at a safe distance (about 1. 5 meters away) at an angle and take note of the failure mode when the specimen fails. (NOTE: Be sure to wear safety glasses.

Do not come close to equipment when the tensile test is running). (3) A plot of tensile stress (Amp) versus tensile strain (mm/mm) will be generated in real-time during the experiment. 2. 6 End of Test (1) The machine will stop automatically when the sample is broken. (2) Press the “Return” button on the digital controller. Both the upper and lower grips will be returned to their original positions automatically. 3) Turn the two handles in the open directions to remove the sample (4) Repeat the previous steps for any additional tests. 5) When finished, save your file and click Finish. This will export your data into a PDF and individual data files. (6) Clean up any broken fragments from the specimens. (7) Turn off the machine and exit the program when finished. Graph UP (50 mm/mm extension), AS (2 feed inputs), PLAN, HIDE and Dentally results using raw data files. There should be two tests for each polymer, but Just pick one to graph. Construct the true stress-strain curves for each polymer (hint: use Equations 3) and (4) provided in the Introduction section).

Calculate Young Modulus for each material and testing condition and compare experimental values with literature values. Discuss any differences in mechanical behavior between the polymers (use pictures! ) Analyze the fracture modes of each sample (ductile fracture, brittle fracture, or intermediate fracture mode). Using the data for polypropylene, discuss the effects of strain rate on the mechanical behavior of the polymers. Using the data for polystyrene, compare effects of feed direction on the mechanical behavior. Explain any unexpected results.

In the past year the information is fetched on developments, inventions and hereafter is explained in perceptible mode

In add-on to the aforesaid benefits, fibre optics overseas telegrams have high electrical opposition, are non affected by electromagnetic Fieldss, secure, and low weight. Even so, short distance communications usually rely on electrical Cu wiring due to its much lower cost, easiness of usage, and ability to transport a current. Other utilizations of fibre optics include medical imagination and as centripetal tools.

A The subject about the integrated-optic modulators in high velocity fiber-optic links, operation of devices used to externally modulate light beginnings used with fiber-optic ushers has been explained in a perceptible mode

Introduction

A fiber-optic communicating system uses the same basic functional constituents as a copper-based communicating system-a sender, receiving system and transmittal medium-except that a fibre-optical nexus ( FOL ) uses optical fiber ( in topographic point of Cu overseas telegram ) as the transmittal medium. Here the optical fiber connects the sender and the receiving system. It carries information in the signifier of light and mainly consists of three parts, viz. , the nucleus, the facing, and the buffer or coating that is used to give strength and protection to the fiber overseas telegram. The nucleus is the cardinal portion of the fiber through which light base on ballss because of the procedure of entire internal contemplation. The cladding surrounds the nucleus, with a different refractile index so that light go throughing through the nucleus stays in that part. The sender consists of an electrical interface, optical modulator and light emitter, and a optical maser rectifying tube or LED for encoding. At the other side, to change over visible radiation into an electrical signal, the receiving system uses either a PIN photodiode or an avalanche photodiode ( APD ) . Several other constituents take portion in set uping an optical fiber nexus ; for illustration, multiplexer, de-multiplexer, signal regenerators, signal repeaters ( or optical amplifiers ) , couplings and splitters. In an optical transmittal system, pick of optical modulators plays an of import portion in the overall public presentation of the system. In this article, we ‘ll concentrate on high-velocity optical modulators, but before we dwell on them in item have a expression at the rudimentss of optical modulators.

Optical Modulators

Converting information in the signifier of electric signals into light moving ridges is known as optical transition. This sort of transition can be achieved either straight or externally. In direct transition, information in the signifier of electric signals is applied straight to the light beginning. Many links use this sort of technique to cut down complexness of the system, but when informations rates or the length of the nexus additions, ‘on’/’off ‘ velocity restriction of the optical maser generates waveguide chirp and stage transition. This causes amplitude transition deformation at the receiving system side, which is unwanted for high-definition, high-data-rate communicating. In such a state of affairs, a continuously-‘on ‘ optical maser beginning provides a better solution. That is the basic thought of indirect transition or external transition. In direct transition, digital logic province ‘1’/’0 ‘ is applied straight as ‘on’/’off ‘ electric signal or two different degrees of electromotive force to the light beginning. In these fortunes, factors like clip invariable of the drive circuitry, building of the visible radiation beginning itself and the features of the transmittal medium ( say, optical fibre ) affect the highest frequence at which the visible radiation beginning can run. Using high-velocity layout and microwave design techniques and high velocity short-pulse integrating ; the job with the circuit and transmittal medium can be minimized. But as stated earlier, the major restriction of this technique is exchanging of the visible radiation beginning itself. In a typical optical maser beginning, this shift cause ‘s electrical and thermic emphasis, which consequences in a frequence displacement known as ‘chirp, ‘ transients and decreased life of the light beginning? In external transition, the optical maser rectifying tube itself stays unmodulated. Data is delivered straight to electrically modulate the crystalline stuff like Li niobate. This device can repeatedly exchange visible radiation without impacting the light beginning. Three types of external modulators are normally used: electro-absorption modulators based on Ga – arsenide ( GaAs ) or indium-phosphate ( InP ) semiconducting material, electro ocular modulators based on polarized polymers, and modulators based on electro ocular crystals like Li niobate and other stuffs. Fig. 2 shows the basic difference between direct and external modulators.

Over the period, external modulators based on Li niobate ( LiNbO3 ) have become more popular because of its low optical loss and high electro ocular coefficient. Next is described the working of amplitude and stage modulators, followed by their comparing with semiconducting material modulators based on GaAs ( gallium arsenide ) and InP ( indium phosphate ) . There are two normally used types of optical modulators in fibber ocular communicating systems: the electro soaking up modulator ( EAM ) and the Mach-Zehnder modulator ( MZM ) .

Electro Absorption Modulator ( EAM )

EAM is little and can be integrated with the optical maser on the same substrate. An EAM combined with a CW optical maser beginning is known as an electro soaking up modulated optical maser.

An EML consist of a CW DFB optical maser followed by an EAM, as shown above. Both devices can be integrated monolithically on the same InP substrate, taking to a compact design and low yoke losingss between the two devices.

The EAM consists of an active semiconducting material part sandwiched in between a p- and n-doped bed, organizing a p-n junction. The EAM works on the rule known as Franz-Keldysh consequence, harmonizing to which the effectual set spread of a semiconducting material decreases with increasing electric field.

Without bias electromotive force across the p-n junction, the set spread of the active part is merely broad plenty to be crystalline at the wavelength of the optical maser visible radiation. However, when a sufficiently big contrary prejudice is applied across the p-n junction, the effectual set spread is reduced to the point where the active part begins to absorb the optical maser visible radiation and therefore becomes opaque.

In practical EAMs, the active part normally is structured as an MQW, supplying a stronger field-dependent soaking up consequence ( known as the quantum-confined Stark consequence ) .

The relationship between the optical end product power, Pout, and the applied contrary electromotive force, Vm, of an EAM is described by the alleged shift curve. The undermentioned figure illustrates such a curve together with the accomplishable ER for a given shift electromotive force, Vsw.

The electromotive force for exchanging the modulator from the on province to the off province, the shift electromotive force Vsw, typically is in the scope of 1.5 to 4 V, and the dynamic ER normally is in the scope of 11 to 13 dubnium.

Because the electric field in the active part non merely modulates the soaking up features, but besides the refractile index, the EAM produces some chirp. However, this chirp normally is much less than that of a straight modulated optical maser. A little on-state ( prejudice ) electromotive force about 0 to 1 V frequently is applied to minimise the modulator chirp.

Lithium Niobate Mach-Zehnder Modulator ( MZ Modulator )

Lithium Niobate Mach-Zehnder modulators are suited for usage in tube, long-haul ( LH ) and extremist long-haul ( ULH ) optical conveyance applications.

The incoming optical signal is split every bit and is sent down two different optical waies. After a few centimeters, the two waies recombine, doing the optical moving ridges to interfere with each other. Such an agreement is known as an interferometer.

If the stage displacement between the two moving ridges is 0A° , so the intervention is constructive and the light strength at the end product is high ( on province ) ; if the stage displacement is 180A° , so the intervention is destructive and the light strength is zero ( off province ) .The stage displacement, and therefore the end product strength, is controlled by altering the hold through one or both of the optical waies by agencies of the electro-optic consequence. This consequence occurs in some stuffs such as Li niobate ( LiNbO3 ) , some semiconducting materials, every bit good as some polymers and causes the refractile index to alter in the presence of an electric field.

The guided-wave LiNbO3 interferometers used to modulate optical maser beams was fabricated every bit early as 1980. LiNbO3 has been the stuff of pick for electro-optic MZ modulator because it combines the desirable qualities of high electro-optic coefficient and high optical transparence in the near-infrared wavelength used for telecommunications.LiNbO3 MZ modulator can run satisfactorily over a wavelength scope of 1300 – 1550nm. It has been widely used in today ‘s high-velocity digital fiber communicating.

LiNbO3 MZ modulators with stable operation over a broad temperature scope, really low bias-voltage impetus rates, and bias-free operation are commercially available. High-speed, low-chirp modulators are needed to take advantage of the broad bandwidth of optical fibers. Modulators have became a critical constituent both in the high-velocity time-domain-multiplexing ( TDM ) and wavelength-division-multiplexing systems ( WDM ) .

Modulators have been traditionally used to modulate a uninterrupted moving ridge ( CW ) optical maser to bring forth the digital signal to be transmitted through a fiber. High-speed modulator with & gt ; 40GHz bandwidth has been fabricated. Low drive-voltage operation is the key to brining such modulators into practical usage because this eliminates the demand for high-octane electrical amplifiers.

There is general a trade off between the velocity and the thrust electromotive force. The modulator chirp must besides be taken into consideration in the nexus design. The design of the modulator and the associated chirp can be used as a grade of freedom to widen nexus distance.

Indium Phosphide Mach Zehnder Modulator with DWDM Laser

Figure 1 shows the construction of the n-i-n optical wave guide. The construction consists of n-InP facing, an undoped InGaAlAs/InAlAs MQW ( I»PL = 1.37 I?m ) , an Fe-doped SI-InP bed ( Semi-Insulating InP bed ) , and an n-InP facing laminated in this sequence on an SI-InP substrate. In order to avoid losingss of the electrical signal and the optical signal caused by the p-type semiconducting material bed, both the signal and land electrode beds are made with n-type semiconducting material beds in which the loss is about 1/20 of that in the p-type. Besides, a high dislocation electromotive force feature is assured by infixing an SI-InP bed doped with Fe between the n-type clad bed and the i-MQW optical guiding bed. The SI-InP and i-MQW beds are 1.0 and 0.3 I?m. Since the electric field is applied in the limited part within the SI-InP and i-MQW beds, the efficiency of transition of the refractile index by the electro ocular consequence can be made larger. Therefore, low-tension operation and optical transition with a short electrode length can be realized.

Fig. 1. Cross-sectional geometry of the n-i-n wave guide

In LiNbO3 and III-V semiconducting materials, they are

I?33 = 30.8 pm/V ( LiNbO3 modulator )

I?41 a‰? 1.4 pm/V ( InP modulator )

The coefficient in the semiconducting material is about 1/20 that of LiNbO3. However, while the refractile index of LiNbO3 is 2.2, that of the semiconducting material is about 3.2, so that the existent fluctuation of the refractile index in the semiconducting material is 1/7 that of LiNbO3. Therefore, when an optical modulator utilizing the electrooptic consequence is fabricated, the key to size decrease is how the high-density electric field is applied to the optical field. When the constructions of the optical wave guides are compared, the breadth of the n-i-n optical wave guide is A? that in the LiNbO3 modulator and the electrode spacing is from 1/30 to 1/50, so that an electric field more than 100 times as great is applied. Therefore, even with a shorter electrode, fluctuations of the refractile index take topographic point and stage transition can be achieved.

To run an optical modulator, an electrode constellation with a distributed component type is effectual, since it is non band-limited by the CR clip changeless. In this manner, a going moving ridge electrode constellation is formed, along which the electrical signal propagates in the same way as the optical moving ridge for optical transition. In order to execute ultra-fast, high-efficiency optical transition with a going moving ridge electrode, two conditions, speed fiting between the optical and electrical moving ridges, and electric resistance matching with a drive system, are of import.

a exposure of the bundle for the push-pull constellation

Features

aˆ? Voltage programmable end product power control

aˆ? Long draw public presentation with negligible punishment

aˆ? Integral Etalon wavelength stabilization to within A± 20 autopsy over life

aˆ? Differential or individual 50 Ohm low electromotive force thrust transition input

aˆ? Integral thermo-electric ice chest with preciseness NTC thermal resistor for temperature control

aˆ? Hermetically sealed butterfly manner bundle with SMA RF connections

aˆ? ITU Wavelengths available from 1527 nanometer to 1608 nanometer

aˆ? 50 GHz channel spacing

Parameter Conditions Min Typ Max Unit

FIBER OPTIC TECHNOLOGY MICROWAVE AND MILLIMETER WAVE SYSTEMS

Side igniter eliminates the dead-zone.

Fibre ocular engineering, traditionally used for long draw communications, is happening new applications in short draw communicating systems in military airborne and shipboard platforms. New commercial services such as fibre-to-the-premise for broadband to the concern and place, broadband radio Internet, and digital picture services are being installed across the USA. The service suppliers and installers of these new systems require new methods of proving fibre ocular nexus public presentation in distances from a few metres to less than 1 Km. Optical clip sphere reflect metres ( OTDRs ) traditionally are used for long haul communicating systems but are limited in their usage in military systems and new commercial services due to dead zones. Artisan Laboratories Corporation has developed the Side igniter ( Patent Pending. ) ; a new trial and measuring system eliminates the dead-zone associated with OTDRs therefore doing it attractive for both military and new commercial applications. The Side igniter has a declaration of a few centimeters and is field portable.

Radar and Communication System Testing

Radar and communicating system trials require out-of-door scopes to find system public presentation. Using an out-of-door scope is expensive and clip devouring so alternate solutions are sought. Radar trials use fixed marks stat mis off from the radio detection and ranging for standardization. Microwave clip holds can be used to imitate marks that allow for proving in a research lab puting. Many bidirectional ( Patent pending ) microwave communicating channel simulator for two manner wireless have been developed the designed demonstrated transmittal at RF and micro-cook frequences that advanced microwave mark allow testing in a research lab environment.

Communicationss

Fibre ocular transmittal of digital informations for long draw and metro entree is widely used in the telecommunications industry. As new services are being developed and offered, such as PCS, Broadband Wireless Internet, Digital Video, and Passive Optical Networks, new chances for parallel fibre ocular distribution are emerging. The presentation of a DWDM parallel fibre ocular system used to administer PCS and Broadband. Wireless Internet showed that administering RF over fibre up to 3 GHz has the advantage of simplifying the system architecture and cut downing base station complexness.

In this presentation, a DWDM broadband photonic conveyance system was able to run into the demands for both IS-95 Personal Communications Services operating at 1.9 GHz and Broadband Wireless Internet operating over the set of 2.5 to 2.7 GHz. Each DWDM channel operates from 1 to 3 GHz and conveyances services up to 80 Km.Artisan Laboratories Corporation presently offers optical transmittal equipment suited for these applications.

Spacecraft

New developments for the following coevals of communicating orbiters and infinite based radio detection and ranging systems include the application of active phased array aerial. In communicating systems, active phased array aerial offer on-board reconfigurability and multi-beam operation. These characteristics greatly cut down concern hazard by leting the beam form to alter depending on client demands. Fibre ocular distribution has been proposed for the transmittal of microwave signals from the orbiter coach to the phased array aerial. The advantages of utilizing this engineering are higher stage stableness with temperature due to the fibre mechanical to belongingss ; lighter weight and flexibleness of the fiber ; and smaller size of the optical interconnect and optical power splitters. The usage of fiber besides allows for a high degree of integrating with antenna elements therefore cut downing size and weight. Developers are presently developing multi-level microwave photonic faculties that utilize such integrating.

While these new developments show promise, fibre ocular distribution has the disadvantage of high power ingestion compared with inactive webs such as coaxal transmittal lines. The increased demand on power ingestion can do the usage of fiber in ballistic capsule prohibitive. To do fibre ocular signal distribution competitory with other transmittal engineerings, Scientists are presently developing a new type of fibre ocular engineering call Ultra visible radiation Fibre Optic Link that can significantly cut down the premier power ingestion of the distribution system.

Satellite Communicationss

SATCOM applications make usage of fibre ocular links to have signals from the aerial at a distant location such as a shelter. These links are normally available and operate at an IF of 70 MHz. This architecture requires a low noise amplifier ( LNA ) , frequency interlingual rendition circuitry ( down- convertors ) , local oscillators, filters and a optical maser sender all located at the aerial site.

Architecture allows for the transmittal of the RF or micro-cook frequence from the orbiter aerial straight over fiber to an integrated exposure receiving system and down-converter system located at a shelter. This architecture reduces the equipment required at the aerial site to the LNA and optical maser sender. Many research labs are offering a high public presentation Low Noise Optical Transmitter System and Integrated Photo receiver Down-Converter System that directs the signal straight from the aerial to a microwave modem. The Low Noise Optical Transmitter System is connected straight to satellite antenna systems extinguishing the demand for a separate low noise amplifier. The Integrated Photo receiver Down-Converter System is an all- in-one system that detects RF and microwave signals over fiber, amplifies the signals, and down-converts them to an intermediate frequence ( IF ) to interface with commercially available microwave informations modems. This system can observe RF over fiber at transition frequences up to 6 GHz and can change over the transition to an IF of 70 MHz or 140 MHz.

In applications in which signals from multiple SATCOM aerial must be combined and distributed, DWDM parallel fibre ocular transmittal can be employed. DWDM sender and receiving system capableness include signal transmittal over 100 Km and bandwidth that exceeds multiple octaves with a CNR of 32 dubnium in the set of 950 to 2150 MHz.

light beginnings used with fiber-optic

Optical Beginning

The basic demands for the visible radiations beginnings used in optical communicating systems depend on the nature of the intended application ( long-haul communicating, local-area web, etc. ) . Both light-emitting rectifying tubes ( LEDs ) and laser rectifying tubes are used as beginnings. Laser rectifying tubes have the advantage of high power ( 10s of mW ) , high velocities, and narrow spectral breadth. LEDs have the advantages of huskiness, dependability, lower cost, long life-time, and simpleness of design. However, they suffer from comparatively broader line breadth and lower bandwidth.

If we use external wavelength filters, this may diminish the power coupled. Even at a individual “ colour ” ( wavelength ) several manners may be present. Matching to a single-mode fibre will lose the power in these other manners.

Therefore the chief characteristics for a light beginning are:

1 ) Power. The beginning power must be sufficiently high so that after transmittal through the fibre the standard signal is noticeable with the needed truth. This includes stableness of that power both in amplitude and frequence.

2 ) Speed. It must be possible to modulate the beginning power at the coveted rate.

3 ) Spectral line breadth. The beginning must hold a narrow spectral line breadth so that the consequence of chromatic scattering in the fibre is minimized. What is the consequence of a finite I”I» ( scattering ) on your system?

4 ) Noise. The beginning must be free of random fluctuations.

5 ) Emission wavelength. Contrast to fiber fading.

6 ) Emission pattern – The beginning power must be coupled to the fibre. Both light end product country and manner distribution in the beam can be of import.

Light moving ridges travel in the optical fibre in the signifier of manners, each with a distinguishable spacial distribution, polarisation, extension invariable, group speed, and fading coefficient. Thus the fibre chosen for your system must run into the design ends after consideration of:

1 ) Multi-mode fibre whether step-index, or graded-index. Single-mode fibre.

2 ) Core size

3 ) Core refractile index profile

4 ) Bandwidth and scattering features

5 ) Attenuation dB/km ( including any connections and splicings ) which is a map of cardinal wavelength.

Fibers are widely used in light applications. They are used as light ushers in medical and other applications where bright visible radiation demands to be shone on a mark without a clear line-of-sight way. In some edifices, optical fibres are used to route sunshine from the roof to other parts of the edifice ( see non-imaging optics ) . Optical fiber light is besides used for cosmetic applications, including marks, art, and unreal Christmas trees. Swarovski dress shops use optical fibres to light their crystal show windows from many different angles while merely using one light beginning. Optical fiber is an intrinsic portion of the light-transmitting concrete edifice merchandise, LiTraCon.

A Frisbee illuminated by fiber optics

A fiber-optic Christmas Tree

A fiber-optic Christmas Tree

Optical fiber is besides used in imaging optics. A consistent package of fibers is used, sometimes along with lenses, for a long, thin imagination device called an endoscope, which is used to see objects through a little hole. Medical endoscopes are used for minimally invasive exploratory or surgical processs ( endoscopy ) . Industrial endoscopes ( see fiberscope or bore range ) are used for inspecting anything difficult to make, such as jet engine insides.

An optical fiber doped with certain rare-earth elements such as Er can be used as the addition medium of a optical maser or optical amplifier. Rare-earth doped optical fibres can be used to supply signal elaboration by splicing a short subdivision of doped fiber into a regular ( undoped ) optical fiber line. The doped fiber is optically pumped with a 2nd optical maser wavelength that is coupled into the line in add-on to the signal moving ridge. Both wavelengths of visible radiation are transmitted through the doped fiber, which transfers energy from the 2nd pump wavelength to the signal moving ridge. The procedure that causes the elaboration is stimulated emanation.

Optical fibers doped with a wavelength shifter are used to roll up scintillation visible radiation in physics experiments. Optical fiber can be used to provide a low degree of power ( around one W ) to electronics situated in a hard electrical environment. Examples of this are electronics in high-octane aerial elements and measuring devices used in high electromotive force transmittal equipment. Optical fibers are besides used in fibre ocular gyroscopes, and other interferometers instruments.

Principle of operation

An optical fiber is a cylindrical insulator wave guide that transmits light along its axis, by the procedure of entire internal contemplation. The fibre consists of a nucleus surrounded by a facing bed. To restrict the optical signal in the nucleus, the refractile index of the nucleus must be greater than that of the facing. The boundary between the nucleus and facing may either be disconnected, in step-index fiber, or gradual, in graded-index fiber.

Multimode fiber

The extension of visible radiation through a multi-mode optical fiber.

Fiber with big ( greater than 10A I?m ) core diameter may be analyzed by geometric optics. Such fiber is called multimode fiber, from the electromagnetic analysis ( see below ) . In a step-index multimode fiber, beams of visible radiation are guided along the fiber nucleus by entire internal contemplation. Rays that run into the core-cladding boundary at a high angle ( measured relation to a line normal to the boundary ) , greater than the critical angle for this boundary, are wholly reflected. The critical angle ( minimal angle for entire internal contemplation ) is determined by the difference in index of refraction between the nucleus and facing stuffs. Beams that meet the boundary at a low angle are refracted from the nucleus into the facing, and do non convey visible radiation and hence information along the fiber. The critical angle determines the credence angle of the fiber, frequently reported as a numerical aperture. A high numerical aperture allows visible radiation to propagate down the fibre in beams both close to the axis and at assorted angles, leting efficient yoke of visible radiation into the fiber. However, this high numerical aperture increases the sum of scattering as beams at different angles have different way lengths and hence take different times to track the fiber. A low numerical aperture may hence be desirable.

A typical single-mode optical fiber, demoing diameters of the constituent beds.

Optical fiber types.

In graded-index fibre, the index of refraction in the nucleus decreases continuously between the axis and the facing. This causes light beams to flex swimmingly as they approach the facing, instead than reflecting suddenly from the core-cladding boundary. The ensuing curving waies cut down multi-path scattering because high angle beams pass more through the lower-index fringe of the nucleus, instead than the high-index centre. The index profile is chosen to minimise the difference in axial extension velocities of the assorted beams in the fiber. This ideal index profile is really near to a parabolic relationship between the index and the distance from the axis.

Single manner fiber

Fibre with a nucleus diameter less than approximately 10 times the wavelength of the propagating visible radiation can non be modelled utilizing geometric optics. Alternatively, it must be analyzed as an electromagnetic construction, by solution of Maxwell ‘s equations as reduced to the electromagnetic moving ridge equation. The electromagnetic analysis may besides be required to understand behaviors such as spot that occur when coherent visible radiation propagates in multi-mode fiber. As an optical wave guide, the fiber supports one or more confined transverse manners by which visible radiation can propagate along the fiber. Fibre back uping merely one manner is called single-mode or mono-mode fiber. The behavior of larger-core multimode fiber can besides be modelled utilizing the moving ridge equation, which shows that such fibre supports more than one manner of extension ( hence the name ) . The consequences of such modeling of multi-mode fiber about agree with the anticipations of geometric optics, if the fiber nucleus is big plenty to back up more than a few manners.

The wave guide analysis shows that the light energy in the fiber is non wholly confined in the nucleus. Alternatively, particularly in single-mode fibers, a important fraction of the energy in the edge manner travels in the facing as an evanescent moving ridge.

The most common type of single-mode fiber has a nucleus diameter of 8 to 10 I?m and is designed for usage in the close infrared. The manner construction depends on the wavelength of the visible radiation used, so that this fibre really supports a little figure of extra manners at seeable wavelengths. Multi-mode fiber, by comparing, is manufactured with nucleus diameters every bit little as 50 micrometres and every bit big as 100s of micrometres.

Special-purpose fiber

Some special-purpose optical fiber is constructed with a non-cylindrical nucleus and/or cladding bed, normally with an egg-shaped or rectangular cross-section. These include polarization-maintaining fiber and fiber designed to stamp down whispering gallery manner extension.

Photonic crystal fiber is made with a regular form of index fluctuation ( frequently in the signifier of cylindrical holes that run along the length of the fibre ) . Such fibre utilizations diffraction effects alternatively of or in add-on to entire internal contemplation, to restrict visible radiation to the fiber ‘s nucleus. The belongingss of the fiber can be tailored to a broad assortment of applications.

A clinometer used in forestry

The clinometer, known in many fields as an inclinometer, is a common tool used in forestry to measure slope, vertical angles, and – in combination with distance measurements – elevation change or tree heights. How it works A forester using a clinometer makes use of basic trigonometry. First the observer measures a straight-line distance D from some observation point O to the object. Then, using the clinometer, the observer measures the angle a between O and the top of the object.

Then the observer does the same for the angle b between O and the bottom of the object. Multiplying D by the tangent of a gives the height of the object above the observer, and by the tangent of b the depth of the object below the observer. Adding the two of course gives the total height (H) of the object, in the same units as D. [1] Note that since multiplication is distributive it is equally valid to add the tangents of the angles and then multiply them by D: A = tan a B = tan b H = (A ? D) + (B ? D) = (A + B) ? D Note also that both angles should be positive numbers (i. . ignore any minus sign on the clinometer’s scale). Units of measure There are typically three different units of measure that can be marked on a clinometer: degrees, percent, and topo. When buying a clinometer it is important to make sure it is calibrated to units suitable for the intended use.

Tree height measurement

The forester stands at a fixed distance from the base of the tree. The most common distances in the United States are 50 feet (15. 24 m), 66 feet (20. 12 m), and 100 feet (30. 48 m). 2] To obtain accurate readings it is best to use taped measured distance instead of paced distances. For the most accurate readings it is best to use a distance that is not less than the height of the tree being measured. [3], that is, that the clinometer will measure an angle less than 45° (100%). The observer sights to the top of tree, if total height is the desired measurement. If the desired measurement is merchantable height – that is, the height producing timber that can be sold – the observer sights to a point on the tree above which no more merchantable timber is found.

The observer then measures to the bottom of the tree, takes the tangents and multiples them by the distance, and adds the two figures together. This will be the height of the tree. The observer must always measure a leaning tree so that the tree is leaning to the left or right. Measurements should never be taken with the tree leaning toward or away from the observer because this will affect their accuracy because of foreshortening.

Slope measurement. Measuring slope with a clinometer

The clinometer is also commonly used by foresters to obtain the percent slope of terrain. This measurement is based on the same trigonometric principles described above. Slope measurements, however, require that both observer and target be a constant height above the ground; thus a range pole or height of measurement (HI) stick is often used in slope measurements. The Clinometer The clinometer is an optical device for measuring elevation angles above horizontal. The most common instruments of this type currently used are compass-clinometers from Suunto or Silva.

Compass clinometers are fundamentally just magnetic compasses held with their plane vertical so that a plummet or its equivalent can point to the elevation of the sight line. A better clinometer (I believe) is the Abney hand spirit level or clinometer, where the object sighted and the level bubble can be seen simultaneously, so that the index can be set accurately. An Abney clinometer is shown in the photograph. A spirit level is so-called because it contains alcohol in a tube of large radius, in which the bubble moves to the highest point.

Spirit levels are used for accurate surveying, although automatic levels that go back to the principle of the plummet are now frequently found, and are easy to use. The Abney clinometer has a sighting tube with an angle scale reading from -90° to +90°, and a spirit level with a Vernier index that can be moved along the scale while the user looks through the sighting tube. A small mirror and lens makes the level bubble visible in the field of view. When the object is aligned with the crosshair in the sighting tube, the spirit level is rotated so that the bubble is bisected by the crosshair, as illustrated in the diagram.

Then, the elevation of the line of sight can be read off on the scale. The Vernier can be read to 10′, but it requires a magnifier to do this. The clinometer can read easily and accurately angles of elevation that would be very difficult to measure in any other simple and inexpensive way. A fairly common use of a clinometer is to measure the height of trees, which is easily done. A point should be marked with a stake as far from the centre of the trunk of the tree as its estimated height, so that the elevation angle is about 45°, which gives the best “geometry. This distance D is measured with a tape. The observer then stands over the stake and sights the top of the tree, finding its elevation angle ?. The height H of the tree is then H = D tan ? + HI, where HI, the height of instrument, is the height of the observer’s eye. All this is illustrated in the diagram. A useful accessory is a levelling rod, which can be home-made at little expense. Since the clinometer has no powerful telescope, the reading of the rod must be evident from a distance if you use it as a self-reading rod.

Alternatively, if you have a rodperson, she can stand by the rod and move a finger or other marker up and down in response to your signals, then measure the distance with a tape. A self-reading rod can be made from a 1″ x 4″ x 10′ choice pine board available at Home Depot. A bold pattern that can be estimated to a few centimetres can then be applied by stencil and matte black spray paint. Two examples are shown at the right. Colors can also be used to make distinctions. The determination of the difference in elevation of two points is called levelling, and can be carried out with the clinometer set at 0°.

The place where you stand with the level is called a turning point, TP. Your rodperson holds the rod on the first point, and you make a backsight, BS, by reading the rod. The reading is the HI above the first point. Now the rod is held on the second point, and a foresight, FS, is taken. Foresights and backsights should be roughly equal in distance. The difference in elevation of the two points is BS – FS. This procedure is illustrated at the left. If both points cannot conveniently be viewed from one TP, a chain of turning points is used, with an intermediate elevation between each one.

The difference in elevation is the sum of the backsights less the sum of the foresights. If the sights are short, such as those that are practical with the clinometer, the curvature of the earth will be taken into account automatically. Clinometer Clinometers are measuring devices that may be used in several different professions. Also known as an inclinometer, the essential function of the device is to determine accurate measurements as they relate to sloping, height and distance.

The clinometer is often used in the profession of meteorology, as well as in forestry and surveying. One of the most common applications of the clinometer has to do with measuring angles as they relate to the slope of natural formations or buildings and other human construction projects. The idea is to measure the angle with an eye toward identifying any amount of slope, with respect to the gravity that is involved. The clinometer may be used to measure both inclines and declines, based on the perspective of the individual calculating the measurements.