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ما هي الخصائص الثابتة؟
ما هي الخصائص الثابتة؟
الخصائص الثابتة هي الخصائص التي تتعلق بالأدوات عندما لا يكون هناك تغيير في الظروف مع مرور الوقت.
ما هي الخصائص الديناميكية؟
ما هي الخصائص الديناميكية؟
الخصائص الديناميكية هي الخصائص التي تتعلق بالأدوات عندما يكون هناك تغيير مع مرور الوقت.
ما هي الخصائص الثابتة؟
ما هي الخصائص الثابتة؟
ما هي الخصائص الديناميكية؟
ما هي الخصائص الديناميكية؟
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ما هو سرعة الاستجابة؟
ما هو سرعة الاستجابة؟
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ما هو التأخر؟
ما هو التأخر؟
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ما هو الدقة؟
ما هو الدقة؟
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ما هو الخطأ الديناميكي؟
ما هو الخطأ الديناميكي؟
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ما هو التجاوز؟
ما هو التجاوز؟
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ما هو الوقت الميت؟
ما هو الوقت الميت؟
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ما هي المنطقة الميتة؟
ما هي المنطقة الميتة؟
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ما هي استجابة التردد؟
ما هي استجابة التردد؟
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ما هي المدخلات القياسية؟
ما هي المدخلات القياسية؟
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ماذا تقصد بنظام من الدرجة صفر؟
ماذا تقصد بنظام من الدرجة صفر؟
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ماذا تقصد بنظام من الدرجة الأولى؟
ماذا تقصد بنظام من الدرجة الأولى؟
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ماذا تقصد بنظام من الدرجة الثانية؟
ماذا تقصد بنظام من الدرجة الثانية؟
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ما هي ثابت الزمن؟
ما هي ثابت الزمن؟
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ما هو وقت الصعود؟
ما هو وقت الصعود؟
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ما هي الاستجابة الترددية؟
ما هي الاستجابة الترددية؟
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ما هي نسبة التردد؟
ما هي نسبة التردد؟
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ما هو التناسبية؟
ما هو التناسبية؟
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Study Notes
Theory of Measurements and Sensors (MEC201)
- This course covers the theory of measurements and sensors.
- The course is taught by Dr. Ashraf Elsayed.
- Various measuring instruments and sensors are pictured.
Chapter (3): Dynamic Characteristics of Measuring Instruments
- This chapter discusses the dynamic characteristics of measuring instruments.
- It covers both static and dynamic characteristics.
- Static characteristics are related to instruments when there is no change in conditions over time.
- Examples include linearity, sensitivity, error, accuracy, precision, and others.
- Dynamic characteristics are related to instruments when there is a change in conditions over time.
- Examples include speed of response, lag, dynamic error, and others.
Introduction (Chapter 3 - a) Speed of Response and Measuring Lag
- Measuring instrument responsiveness is the speed at which an instrument reacts to the change in the measured quantity.
- Lag is the delay or retardation in an instrument's response to changes in the measured variable due to factors like inertia or resistance.
Introduction (Chapter 3 - b) Fidelity (Accuracy) and Dynamic Errors
- Fidelity (accuracy) of the system describes the ability for an instrument to accurately reflect changes in the measured variable without dynamic error or is a faithful reproduction of the output signal from input signal.
- Dynamic error is the difference between the indicated value by the instrument and the true value of the variable changing over time.
Introduction c) Overshoot
- Overshoot is the maximum by which a pointer moves beyond the steady state.
- This happens due to maximum and inertia of the moving part, resulting in delayed adjustment to the deflected position.
Introduction D) Dead Time and Dead Zone
- Dead time is the time it takes for a measuring instrument to start responding to a change in the measured quantity.
- Dead zone is the largest change in the measured variable that does not trigger a response from the instrument, usually caused by friction and backlash.
Introduction (Chapter 3 - E) Frequency Response
- Frequency response refers to the ability of a system to accurately reflect dynamic variable changes.
- Example systems include pressure sensors, associated electronics, and plumbing, which all affect the dynamic frequency response.
- Complete information about the system's output is provided by the frequency response for any given input.
Introduction (Chapter 3 - Standard Test Inputs)
- Measuring and control system dynamic performance is determined by applying known input signals and studying the behaviour of the output signals.
- Common standard inputs for dynamic analysis include step functions, linear (or ramp) functions, and sinusoidal (or sine wave) functions.
Introduction (General Measuring System)
- A measuring system comprises an input signal (the measured quantity, e.g., pressure, temperature, velocity) and an output signal (the resulting response).
- The system processes the input signal to produce a measurable output and this output is often in a different format.
Chapter (3). Measuring System Model
- Differential equations are commonly used to describe measurement systems behavior.
- The system has an nth-order linear differential equation. Input and output variables described by a forcing function.
- Dynamic models are typically analyzed with Laplace transforms.
Zero-Order Systems (n = 0)
- Zero-order systems react instantly to changes in the input.
- Their response is independent of time, and they are used to model non-time dependent systems.
First-Order Systems (n = 1)
- Energy is stored or dissipated in these systems.
- They do not react immediately to an input change, and they are common in systems like thermometers.
First Order Systems - Step Function Input
- The forced function in a first-order system describes a sudden change in magnitude in the input.
- The measuring instrument may not immediately reflect the input change, heat energy may be stored.
First-Order Systems - Energy Conservation Equation
- Energy conservation describes the relationships between heat energy in and out of a system.
- This balance is relevant to processes in systems such as a thermometer.
Time Constant (τ)
- The time constant (τ) is the time needed for the dynamic system's output to reach 63.2% of its final value after a step change.
Rise Time (tr)
- Rise time is the time required for the output to change from 10% to 90% of its final value.
- This is useful to understand a dynamic system's speed.
Second-Order Systems
- These systems involve energy storage elements, such as springs, and damping mechanisms, such as dashpots.
- They are commonly used in mechanical or electrical measuring instruments.
Second-Order Systems - Car Dampers
- Car dampers are a common example of dynamic system, often incorporating springs, moving mass and damping.
Second Order Systems - Energy Storage
- Second-order systems involve a combination of energy storage mechanism such as springs and mass. and damping which can cause periodic responses.
Second Order Systems - Dampening Ratio
- Dampening ratio is related to the energy dissipation within the system and can affect the overshoot.
Second Order Systems - Phase Shift and Frequency Input
- Systems with continuous sinusoidal input signals have specific characteristics for dynamic response.
- Amplitude will be reduced and the signal will have a phase shift compared to the input.
Additional Examples
- Multiple examples are provided for specific types of measurements like thermocouples, for which time constants, natural frequencies, and dynamic errors are calculated in the context of a first or second order system.
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Description
يتناول هذا الفصل الخصائص الديناميكية للأدوات القياسية، حيث يتميز التحديد بدقة المقياس وسرعة الاستجابة. يتم مناقشة الصفات الثابتة والدينامية للأدوات، مع تقديم أمثلة توضيحية لدقة وأخطاء القياس.
