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Introduction to Physical Instrumentation: Preparation, Data Collection, and Analysis

This lecture provides an overview of the preparation of physical instruments, the collection and validation of data, and the analysis of physical data. Examples of instrumentation in different fields are also discussed.

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Introduction to Physical Instrumentation: Preparation, Data Collection, and Analysis

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  1. TGT pramono

  2. Pokokbahasan • Penyiapaninstrumenpenelitianfisik • Penyusunanparemeterfisik • Pengumpulan data 1 • Pengumpulan data 2 • Input data • Data cleaning/validasi • Pengolahan data fisik • Analisis data fisik

  3. PenyiapanInstrumen • Mengapaperlu?

  4. Gaya berpikir

  5. Instrumentation Examples Lecture 3

  6. Strain Measurements Strain gauge Lecture 3

  7. Non-destructive Testing Ultrasound transducer Lecture 3

  8. Automotive Sensors Accelerometer Oxygen Sensor Airflow Sensor Oil Pressure CO Sensor Water Temperature Lecture 3

  9. Biomedical Ultrasound Transducer Lecture 3

  10. What other examples can you think of? Lecture 3

  11. Lingkungan (fisik) • EC meter  EC: mikro mhos/cm2 • pH meter keasaman-kebasaan • DO meter oksigenterlarut • COD  • Turbidity meter Kekeruhan • Ring infiltrometerinfiltrasipermeabilitastanah • Metode: Auger hole permeabilitastanah • Current meter kecepatanaliran • AWLR  automatic water level recorder

  12. Stafgauge = pielscall = papandugatinggimuka air • ARR  automatic rainfall recorder • Lesi meter perkolasi • Pan A evaporasi air bebas • Anemometer kecepatanangin • Camblestokeradiasimatahari • Gelasukurvolumetrik • Soil humidity meter kelembabantanah • OHM meter (Ω) resitivity/tahanan (ketidakhantaranlistrik) lawannyadayahantar (electric conductivity  mhos ( )

  13. Amplifier A Typical Instrumentation System A/D Converter Sensor Computer Lecture 3

  14. Instrumentation System • Sensor-converts the measured value into an electrically useful value. • Amplifier-”conditions” the signal from the sensor. • A/D Converter-converts the signal into a digital format. • Computer-processes, displays, and records the signal. Lecture 3

  15. Sensor • The output of a sensor is proportional to the quantity of interest. • The sensor output may be a • voltage or current (temperature, pressure) • resistance (strain gauge) • frequency (accelerometer) Lecture 3

  16. Amplifier • The output of the amplifier is (usually) a voltage. • The gain of the amplifier is set so that the voltage falls between lower and upper limits (for example, -10V to 10V). Lecture 3

  17. A/D Converter • Analog-to-digital conversion consists of two operations: • Sampling: measuring the voltage signal at equally spaced points in time. • Quantization: approximating a voltage using 8 or 16 bits. Lecture 3

  18. Instrumentation Issues • Noise • Signal bandwidth • Sampling • Amplifier characteristics • Feedback • Real-time processing • Control systems Lecture 3

  19. Noise Signal Signal + Noise Lecture 3

  20. Sources of Noise • Thermal noise caused by the random motion of charged particles in the sensor and the amplifier. • Electromagnetic noise from electrical equipment (e.g. computers) or communication devices. • Shot noise from quantum mechanical events. Lecture 3

  21. Effects of Noise • Reduces accuracy and repeatability of measurements. • Introduces distortion in sound signals. • Introduces errors in control systems. Lecture 3

  22. What to Do? How can we eliminate or reduce the undesirable effects of noise? • Grounding/shielding electrical connections • Filtering (smoothing) • Averaging several measurements Lecture 3

  23. Signal Bandwidth Conceptually, bandwidth is related to the rate at which a signal changes: Low BW High BW Lecture 3

  24. Bandwidth and Sampling A higher bandwidth requires more samples/second: Low BW High BW Lecture 3

  25. Bandwidth Limitations Every component in the instrumentation system has bandwidth limitations: • Sensors do not respond immediately to changes in the environment. • The amplifier output does not change immediately in response to changes in the input. • The A/D converter sampling rate is limited. Lecture 3

  26. Effects of BW Limitations Sensor Output Amplifier Output Lecture 3

  27. Amplifier Characteristics Amplifiers are characterized in terms of attributes such as: • Gain • Bandwidth and/or frequency response • Linearity • Harmonic distortion • Input and output impedance Lecture 3

  28. Op Amps • One commonly used type of amplifier is the Operational Amplifier (OpAmp). • Op Amps have differential inputs: output voltage is the amplified difference of two input voltages. • Op Amps have very large gains (>103). Lecture 3

  29. Op Amps (cont.) • Most op amp circuits use negative feedback. • Op amp circuits can be designed to: • Provide voltage gain or attenuation. • Convert current to voltage. • Integrate or differentiate. • Filter out noise or interference. Lecture 3

  30. Feedback Often, sensors measure quantities associated with systems. The sensor output is used to control the system in a desired manner. Lecture 3

  31. Example: Industrial Process Control • In many manufacturing processes (integrated circuits, for example) temperatures must be closely controlled. • Feedback can be used to maintain a constant temperature. Lecture 3

  32. Temperature Control The Control System sets the current supplied to the heating elements in the furnace to keep the material temperature at the desired value. Furnace and Material Control System Temperature Sensor Desired Temperature Lecture 3

  33. A car cruise control is a feedback system. How does it work? Lecture 3

  34. Benefits of Feedback • Provides stability with respect to changes in system parameter values. • Helps to obtain a (nearly) linear response from non-linear components. • Can be used to change the characteristics of a system under control. Lecture 3

  35. tq

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