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What are the types of signals that are usually calibrated by a sensor? What is the point of standardization of sensor output interfaces
Signal regulation is broadly divided into five types: electro-balancing, linearization, signal form transformation, filtering, resistance to matching。
The benefits of standardization of the output interfaces: no less than an in-depth understanding of the internal rationale and structure of the functional modules, the personnel concerned can design, realize and maintain the entire system。
What are the disadvantages of passive sensors compared to active sensors
Because of the need to provide incentives for sensitive elements, passive sensors usually have more leads than active sensors, and the overall sensitivity of sensors is influenced by the magnitude of the incentive signals. In addition, the presence of incentive sources may increase the risk of explosion in flammable, explosive gas-prone environments, requiring adequate attention in certain special situations
3. What are the common requirements or characteristics of sensors generally used for networking of goods? What requirements should wireless sensors for field environmental monitoring generally focus on
The most common requirements for 2 sensors for material networking are, in addition to high value, small size and low power consumption, improved performance and ease of use, interfaces to facilitate networked measurements and self-enabling methods。
Sensors are required to be reliable and resistant to interference。
1. What are the general characteristics of sensors? What are the working characteristics of the sensor
The overall properties of the sensor consist mainly of its own characteristics and its matching with the input and output of the measurement system consisting of the object and the back instrument. The sensor's own properties are primarily mechanical and work properties, all of which include static properties, dynamic properties, environmental properties and reliability。
2. What are the static characteristics of sensors? What performance indicators are mainly described
Static properties represent the output-input relationship of sensors when measured to be stable, with key indicators including sensitivity, linearity, delay and repetition。
3. How is the sensitivity of sensors defined? If the sensitivity of a pressure sensor is 1. 5 mv (v. Mpa), this indicates how much pressure the sensor corresponds to and how much volts stimulate the voltage with a variation in the output of 1. 5 mv。
Definition: sensitivity refers to the input and output increment ratio of the sensor。
An output variation of 1. 5 mv at 1mpa pressure and 1v voltage。
4. Why is it only the response of the sensor to the chord-cycle and step-step signals that reflects the characteristics of the sensor
The dynamic properties of the sensor are analysed from both time and frequency domains. Therefore, the response properties to the step leap function are studied in the time domain category and the frequency response properties to the sine function are studied in the frequency domain category. When a step-in input is used to study the dynamic response properties of the domain at the time of the sensor, a composite description is made using parameters such as the rising time tr response time and over-string (or over-blown)。
5. What are the dynamic characteristics indicators for first- and second-stage sensors
First-order sensors: sensors with simple energy transformations, such as most material-type sensors, whose dynamic performance can be described by a first-order differential equation。
Second-stage sensors: the circuits with r, l and c in the electrical system display a second-stage frequency response. Similarly, there are similar properties for sensors with mechanical systems such as measurements and measurements of vibrations that have a barrier, mass, and spring。
How can the sensor be reasonably selected? Which chain does the selection process generally begin
Principle of overall need: the technical indicators of sensors are given as isolated products or components and are not the overall objective of the measurement system, and therefore the selected sensors and measurement methods should be applied in the field as required by the overall design of the measurement system。
The principle of high reliability: to the extent that a wide range of optional sensors meet basic technical indicators, reliability is given primary consideration; and to the extent that performance is satisfied, simple solutions with fewer metrware are used to maximize the reliability of the system。
The principle of high value for money: while meeting the requirements, focus on economics, with low costs for use and maintenance, in addition to low sensor prices。
Reasonable selection includes reasonable selection and correct use, and the selection of sensors has no fixed pattern。
1. What are the common methods of measuring resistance? What are the applicable situations
Diversion. The simplest deflection method is constant-pressure power to measure currents or constant-pressure power to measure electrical resistance。
The split method. The subpressor method is often used to measure highly tissue-changing sensors, as well as resistance of non-linear sensors to thermal sensitivity of negative temperature coefficients。
Bridge law. The simplest method used to measure changes in small resistance values is to balance measurements and regulate the values of standard resisters using electric or manual feedback。
2. What is the sensitivity of the detectable circuit related to the degree of variability in sensitive resistance when an unbalanced voltage is used as an output for a single-arm sensitive electrical resistance bridge? What circumstances are the most sensitive
Non-linear relationships, with highest sensitivity in r1 = r4; r2 = r3。
3. What are the ways to improve the use of bridges with an electric resistance ratio of 1 to the adjacent arm, where sensitive resistance changes are close to or above 100 per cent
The first is the use of analogue or digital techniques to correct non-linear outputs and the second is the sacrifice of sensitivity in exchange for linearity。
4. What are the types of conceiving sensors according to the principles of capacitive change? What are their main uses
1 deviated polar-range capacitor sensors: the differential mode is twice as sensitive as a unipolar one and the non-linear error is significantly reduced. It also effectively compensates for errors caused by temperature changes due to structural symmetry. Due to the extremely high resolution of the variable polar range, it is possible to measure a linear shift of up to 0. 01 m, so it is most widely applied in microtransmission tests。
Ii. Fragmented area capacitive sensors: the fragmented area capable sensor is less sensitive than the variable polar type. The output characteristics of this sensor are linear. The range is therefore not limited by linear ranges and is suitable for measuring larger straight and agular shifts. In practical applications, differential structures are also used to increase sensitivity。
Consistency sensors for the transformation of media: geometry of non-conductive bulk material
5. What are the characteristics and contexts of direct and indirect action, in terms of the composition of the electromagnetic sensor
Direct activation: the directly actuated capacitive sensor is the capacitor and is measured without the need for elastic elements。
Indirect actuation: indirect actuated capacitor sensors consist of elastic elements and capacitors. An intermediate variable is measured by sensitive elements. Sensors such as pressure, shift acceleration, etc. Can be formed depending on the flexibility element。
6. What are the main components of the sensor? What are the types of electron sensors that vary according to the principles of electrons
It's made of steel cores, cortex, wires。
Categorized as: modified vacuum self-sensor, modified air area self-sensor, pyramid self-sensor。
7. Briefly describe the rationale, structure and performance characteristics of the turboflow sensor, indicating the parameters by which the turboflow sensor can be measured directly, and other physical volumes by which it can be measured indirectly。
When the metal conductor is placed in a modified magnetic field or when it moves in the magnetic field, an induction current is generated within the metal conductor, which is called an electric vortex or vortex, because it is self-closed in the metal conductor。
The vortex sensor is simple, easy to use, and is widely used in place transfer, vibration and material parameters measurement, and no damage to the injury. The largest feature is the possibility of non-contact measurements of parameters, the scope and accuracy of which depend on factors such as the size of the sensor's structure, the number of coils and magnetic frequency. Turboflow sensors are divided into high-frequency and low-frequency reflectors。
1. What parameters are the characteristics of elastic elements? What are the benefits of its inherent high frequency? How to estimate the inherent frequency
The characteristics of the elastic component are shown in k for k for sensitivity。
The inherent high frequency reduces dynamic error。
It is generally estimated through a combination of calculations and experiments. The lowest inherent frequency is given in the calculation, which can also be calculated using the formula f=。
2. What is the inhibition effect? What are the structural characteristics of the solid-state resistance device? How can the temperature effect of the pressure resistance factor be compensated
The inhibition effect is used to describe a change in the resistance of the semiconductor by external force. This change only affects the material's electrical resistance rate. Unlike the voltage effect, the inhibition effect cannot be used to generate voltage on equipment。
Four p-type electrical resistances spread over circular silicon film forming the arms of the whistlestone bridge。
Spread resistance on the four arms of the bridge is equal in size and the temperature coefficient is the same, so the zero temperature of the bridge is small。
3. What is the voltage effect? What are the two equivalent circuits with pre-enriched voltage elements? For what application
The voltage effect: when some electrons are distorted by external forces in a certain direction, their internality is polarized, while the opposite charge appears on its two relative surfaces. When the external force is removed, it returns to a state of non-electricity, known as the positive voltage effect。
Pressure amplifiers and charge amplifiers
4. Why cannot a voltage sensor measure a static signal (a description of the input output band relationship analysis from the equivalent circuit)
No, voltage sensors measure only dynamic signals, because the voltage sensors are a typical self-generated sensor, a sensor that converts principles with the voltage effect of some crystal receptors that generate charge on their surfaces. In some crystals, when external forces work in a certain direction, there is an internal polarisation and at the same time a countersigned charge on one or two surfaces. When the external force was removed, it returned to a non-electricity state. The polarity of the charge changes as a force direction, and the amount of charge generated by the crystal receptor is proportional to the size of the external force. This phenomenon is called the positive voltage effect. Most voltage sensors are made from the positive voltage effects of the voltage material. As can be seen from the principles of the voltage sensor, it is a dynamic process that would not be able to react if such voltage changes, which measure slow-change stress signals, were to disappear. So we can't measure the static signal
5. What is the exterior photovoltaic effect, internal photovoltaic effect? What is the photo-conductive and photo-voltaic effect? One or two examples of countermeasures based on these effects are given。
Exterior photoelectric effects: phenomenon of electron spilling of metal surfaces under light
Internal photo-electric effects: the internal photo-electric effects are one of the photo-electric effects, resulting in changes in the chemical properties of the substance (e. G. A change in the electrical resistance rate, which is different from the external photo-electric effects, which are ejections). Internal photovoltaic effects can be divided into photoconductive and photovoltaic effects。
Photo-conductive effects, also known as photoelectric effects, photo-sensitivity effects, are the sum of a type of photo-electric modification that causes changes in the electrical performance of certain objects after the light is exposed to them. When the light is exposed to semiconductor materials, the material absorbs the energy of the photons, turning the non-conductor electronics into the conductor electronics, resulting in an increase in the concentration of the carrying fluids, which leads to an increase in the electrical conductivity of the materials。
The short photo-volt effect is photo-voltaic and refers to a phenomenon where the light produces electrical bit differentials between different parts of the uneven semiconductor or semiconductor and the metal mix。
Chapter iv 1. Briefly describe the thermomechanical principles and methods of thermoelectric dolls. What are the conditions for heat power generation
(1) connecting two different conductors or semiconductors into closed circuits where the temperature of the two points of the circuit is different from that of the two points of the circuit gives rise to thermal power, a phenomenon known as thermal power effect. The thermometeorometer works on this principle。
(2) thermal electrons commonly used are platinum, nickel chromium, nickel silicon, copper, and copper。
What is the hole effect? Why is hall's component susceptible to temperature? How to compensate for the effects of changes in ambient temperature on the halware output
Hole effect: placing a conductor thin or semiconductor thin in a flat field will produce a horizontal electric field in the width direction when the current is controlled along the thin length。
The main factor affecting the temperature properties of the hole element is internal resistance between the hole voltage, the current endpoint and the hole endpoint。
Enter the end and connect the resistance or use thermal sensitivity components。
3. What is the magnetic elasticity and magnetic pressure
All magnetic material has, to some extent, a magnetic elasticity effect, which is due to the balance between the energy of spin-orbit coupling and the elasticity of the substance. Magnetic elasticity is also a necessary consequence of meeting minimum energy conditions. From the very point of view of freedom, when the magnetic state of magnetic material changes, its own shape and size are changed, as this minimizes the total energy of the entire system。
4. Briefly describe the working principles of ultrasound sensors and why are temperature effects considered when using ultrasound ranging
The ultrasound is first launched through an ultrasound generator, then the received ultrasound is converted into a telecommunications number, and the device that completed the work is called the ultrasound sensor。
In cases where range accuracy is too high, temperature can be compensated by measured。
Chapter 6, 7 1
Speciality: only a description of the equivalent or non-equisition of temperature, which cannot be added or subtracted。
Exposure and non-exposure temperature measurements。
3. Exposure-type thermometric characteristics: this measure is intuitive, reliable and relatively simple。
4. Non-contact temperature measurement characteristics: do not destroy the original temperature field
There is a higher temperature measurement cap, which means dry measurements of the temperature of moving objects and faster changes。
U = 0. 08 so t = 500. 08 = 625°c and t = t-40°c so t = 625+40 = 665°c
1. Advantages: high sensitivity, small size, rapid response, low utility and low price。
2. Disadvantages: resistance values show non-linear variations with temperature, and components are not interchangeable。
3. Practicality: if temperature measurements are small, they require sensitivity
We can use heat-sensitive electrical resistance. When the range is large and accurate, thermal resistance is used。
1 intermediate conductor's law: in the thermoelectric doll's circuit, if the
The interconductor c has the same temperature at both ends, and access to the intermediate conductor c has no effect on the total thermodynamic e of the dot back. Meaning: provide methods and bases for measuring thermal power。
2 intermediate temperature law: thermal voltage of thermoelectric dolls at both ends at tn and tc equals the sum of thermal voltage of the same thermoelectric dolls at tn, tm, tc at both ends, or tm between tn and tc, i. E
E(tn, tc) = e (tn, tm) + e (tm, tc) is the cold end temperature tc = 0 and the heat temperature is tn. E (tn, tm) is thermal power of tm at the cold end and tn at the heat end. E (tm, tc) is the cold temperature tc = 0 and the heat temperature is tn. Meaning: a theoretical basis has been laid for the development of the thermoelectric pediatric scale。
34. 84mv
Six
Refractive fibre-optic temperature sensors
Linear arrays: applications for scanners, fax machines and photocopying machines are systems that use lined ccds for pacing scanning campaigns。
2. Platform: image capture and identification for automatic control and automatic measurement。
Common elements: lightness control is available and light-sensitive diodes are used. Differing: light amplifiers are required for photo sensors. A bright sensor requires an extra component。
2. Photometric sensor use: automatic use primarily for lamps
Lighting/expiring controls, such as street lights, advertising lights, and automatic background lighting。
3. Lightness sensor applications: backlight brightness can be automatically adjusted for environmental brightness。
Fibre-optic voltage sensor
