scholarly journals PULSE METHOD FOR DETERMINATION OF TIME PARAMETERS THERMAL FIRE DETECTOR

2021 ◽  
Vol 4 (164) ◽  
pp. 166-170
Author(s):  
Ya. Kozak
Keyword(s):  
Electric Current ◽  
Time Constant ◽  
Sensitive Element ◽  
Integral Transformation ◽  
Pulse Method ◽  
Auxiliary Parameter ◽  
Sensing Element ◽  
Fire Detector ◽  
Time Parameters ◽  
Analytical Expressions

For thermal fire detectors with a thermoresistive sensitive element, the method of determining its time parameters is justified. The time parameters of operation and the time constant of the thermal fire detector are considered as time parameters. The method is based on the use of the Joule-Lenz effect, for the implementation of which single pulses of electric current are passed through the thermoresistive sensitive element of the fire detector. Pulses having the shape of a quarter sinusoid or a quarter cosinusoid are used as such test signals. Using the Laplace integral transformation, analytical expressions are obtained, which represent the formalization of the reaction of the thermoresistive sensitive element of the fire detector to the corresponding test signals. These analytical expressions are used to obtain the functional dependences of the fire detector time constants on the pulse duration of the electric current and the auxiliary parameter. The auxiliary parameter is the ratio of the values ​​of the output signal of the thermal fire detector at two fixed points in time. This choice of auxiliary parameter allows to ensure invariance with respect to the transfer coefficient of the thermal fire detector with a thermoresistive sensing element. The fixed moments of time are chosen to be equal to half and three quarters of the duration of the pulses of electric current flowing through the thermoresistive sensitive element of the fire detector. The time of operation of the thermal fire detector is determined in the form of two additive components, one of which is a time constant of the fire detector, and the other is determined by the values ​​of normalized parameters in accordance with existing regulations. A sequence of procedures is given, which together represent a method of determining the time parameters of thermal fire detectors of this type.

scholarly journals TEMPERATURE ERROR WHEN DETERMINING THE TIME PARAMETER OF A FIRE DETECTOR WITH A THERMORESISTIVE SENSITIVE ELEMENT

2021 ◽  
Vol 6 (166) ◽  
pp. 151-155
Author(s):  
Ya. Kozak
Keyword(s):  
Electric Current ◽  
Current Pulse ◽  
Mathematical Description ◽  
Sensitive Element ◽  
A Priori ◽  
Time Parameter ◽  
Temperature Error ◽  
Electric Current Pulse ◽  
Sensing Element ◽  
Fire Detector

For fire detectors with a thermoresistive sensing element, a mathematical description of the reaction to the thermal action of an electric current pulse flowing through such a sensing element and having the shape of a right triangle is obtained. The mathematical description is constructed using the Laplace integral transformation and is shown to be a superposition of two Heaviside functions. The parameters of these functions are determined by the transmission coefficient and time constant of the thermoresistive sensitive element of the fire detector and the amplitude and duration of the electric current pulse. It is shown that the ratio of the output signals of the thermoresistive sensitive element of the fire detector at two a priori given moments of time can be used to determine the time parameter of the fire detector. The values ​​of a priori set moments of time, in which the temperature of the thermoresistive sensitive element of the fire detector is determined, are selected under the condition of simplicity of technical implementation. If there is a change in ambient temperature, it leads to a temperature error as a function of the time parameter of the fire detector. For such an error, a mathematical description is obtained in the general case, as well as for the case when the thermal influence on the thermoresistive sensitive element of the fire detector is due to the flow of an electric current pulse in the form of a right triangle. It is shown that the value of the temperature error has a minimum at the values ​​of the ratio of the output signals of the thermoresistive sensitive element of the fire detector at two a priori time points belonging to the range The value of this error does not exceed 4.9% with variations in ambient temperature, the value of which does not exceed 2.0%.

scholarly journals Substantiating the pulse method for determining the time parameter of fire detectors with a thermoresistive sensing element

2021 ◽  
Vol 6 (5 (114)) ◽  
Author(s):  
Yuriy Abramov ◽  
Oleksii Basmanov ◽  
Yaroslav Kozak
Keyword(s):  
Mathematical Model ◽  
Transfer Function ◽  
Electric Current ◽  
Integral Transformation ◽  
A Priori ◽  
Single Pulse ◽  
Pulse Method ◽  
Time Parameter ◽  
Sensing Element ◽  
Equations Of Mathematical Physics

This paper substantiates the pulse method for determining the time parameter for fire detectors with a thermoresistive sensing element ‒ the time constant. The method is based on using the Joule-Lenz effect, which manifests itself when an electric current pulse passes through the thermoresistive sensing element of fire detectors. Thermal processes in such a sensing element are described by a mathematical model that belongs to the class of equations of mathematical physics. The solution to the differential equation of this class was derived using the Hankel integral transformation and is represented as a series relative to the Bessel functions. The resulting solution is used to construct a mathematical model of a thermoresistive sensing element in the form of a transfer function, which takes the form of the transfer function of the inertial link. To trigger the thermoresistive sensing element of fire detectors, a single pulse of electric current in the shape of a rectangular triangle is used. The integral Laplace transformation was applied to mathematically describe the response of a thermoresistive sensing element to the thermal effect of such a test influence. To obtain information about the time parameter of fire detectors with a thermoresistive sensing element, the ratio of its output signals is used, which are measured in the a priori defined moments. A two-parametric expression was built to determine the time parameter of fire detectors; a verbal interpretation of the pulse method to determine it was provided. The implementation of this method ensures the invariance of the time parameter of fire detectors with a thermoresistive sensing element relative to the amplitude of a single pulse of an electric current, as well as relative to the parameter that is included in its transfer coefficient.

Extended electric power sources

2018 ◽  
Author(s):  
T.A. Konev ◽  
V.A. Kuzmin ◽  
E. Yu. Mutovina ◽  
R.D. Puzhaykin ◽  
Vladimir Salomatov
Keyword(s):  
Electric Power ◽  
Electric Current ◽  
Load Resistance ◽  
Active Power ◽  
Operating Voltage ◽  
Power Sources ◽  
Distributed Parameters ◽  
Analytical Expressions ◽  
Characteristic Resistance ◽  
Length Effects

Chemical sources of current are investigated as lines with distributed parameters. Analytical expressions are obtained for the voltage and active power values of the source at different distances from the beginning of the cell as well as dependences of the working voltage and active power on the source length. Effects of a reduction in the operating voltage and active power are due to the flow of electric current along the source during operation. The magnitude of these effects depends not only on the length of the source, but also on the ratio of characteristic resistance to the load resistance.<br>

scholarly journals Kinetics of Recovery of the Dark-adapted Salamander Rod Photoresponse

1998 ◽  
Vol 111 (1) ◽  
pp. 7-37 ◽  
Author(s):  
S. Nikonov ◽  
N. Engheta ◽  
E.N. Pugh
Keyword(s):  
Theoretical Analysis ◽  
Time Constant ◽  
Translation Invariance ◽  
Flash Intensity ◽  
Translation Invariant ◽  
Calcium Dependent ◽  
The Difference ◽  
Analytical Expressions ◽  
Kinetics Of ◽  
Flash Response

The kinetics of the dark-adapted salamander rod photocurrent response to flashes producing from 10 to 105 photoisomerizations (Φ) were investigated in normal Ringer's solution, and in a choline solution that clamps calcium near its resting level. For saturating intensities ranging from ∼102 to 104 Φ, the recovery phases of the responses in choline were nearly invariant in form. Responses in Ringer's were similarly invariant for saturating intensities from ∼103 to 104 Φ. In both solutions, recoveries to flashes in these intensity ranges translated on the time axis a constant amount (τc) per e-fold increment in flash intensity, and exhibited exponentially decaying “tail phases” with time constant τc. The difference in recovery half-times for responses in choline and Ringer's to the same saturating flash was 5–7 s. Above ∼104 Φ, recoveries in both solutions were systematically slower, and translation invariance broke down. Theoretical analysis of the translation-invariant responses established that τc must represent the time constant of inactivation of the disc-associated cascade intermediate (R*, G*, or PDE*) having the longest lifetime, and that the cGMP hydrolysis and cGMP-channel activation reactions are such as to conserve this time constant. Theoretical analysis also demonstrated that the 5–7-s shift in recovery half-times between responses in Ringer's and in choline is largely (4–6 s) accounted for by the calcium-dependent activation of guanylyl cyclase, with the residual (1–2 s) likely caused by an effect of calcium on an intermediate with a nondominant time constant. Analytical expressions for the dim-flash response in calcium clamp and Ringer's are derived, and it is shown that the difference in the responses under the two conditions can be accounted for quantitatively by cyclase activation. Application of these expressions yields an estimate of the calcium buffering capacity of the rod at rest of ∼20, much lower than previous estimates.

scholarly journals The Study of the Structure Based on the Array of ZnO-Nanorods as a Sensor of the Gas Flow Rate

Proceedings ◽  
2020 ◽  
Vol 42 (1) ◽  
pp. 42
Author(s):  
Victor Petrov ◽  
Alexandra Starnikova
Keyword(s):  
Sensitive Element ◽  
Gas Flow ◽  
Air Flow ◽  
Zno Nanorods ◽  
Zno Nanorod ◽  
Gas Flow Rate ◽  
Sensing Element ◽  
Air Velocity ◽  
Oxide Semiconductors ◽  
Air Flow Velocity

This work shows the possibility of using arrays of ZnO nanorods grown on a glass substrate as a sensitive element for measuring air flow velocity. Since oxide semiconductors have a temperature dependence of resistance, a theoretical and experimental assessment was made of the influence of air velocity on the increase in resistance of a sensitive element. It has been theoretically shown that when air is blown through, the temperature of the free end of the ZnO nanorod can decrease by several degrees. An experimental evaluation showed that when gas is blown at a speed of 12.5 cm/s, the resistance of the sensing element increases by about 20%, which is equivalent to a temperature increase of about 4 degrees. In addition, it was found that the dependence of the increase in the resistance of the sensitive element when exposed to an air flow from 0 to 12.5 cm / s is close to linear.

scholarly journals Information and measurement system of weapon stabilization parameters based on precision piezoelectric sensitive element

2020 ◽  
Vol 166 ◽  
pp. 05005
Author(s):  
Andrii Tkachuk ◽  
Olena Bezvesilna ◽  
Oleksandr Dobrzhanskyi ◽  
Anna Ostapchuk ◽  
Mykola Horodyskyi
Keyword(s):  
Measurement System ◽  
System Performance ◽  
Sensitive Element ◽  
Measurement Accuracy ◽  
Classical System ◽  
Sensing Element ◽  
External Disturbances ◽  
Accuracy Improvement ◽  
Constructive Methods ◽  
Signal Amplifier

The structure and principle of information and measurement system performance of weapon stabilization are described. Established, that the classical stabilization system consists of a stabilizing platform of the sensitive element (or block of sensitive elements), defining the absolute angle of platform α rotation, the sensing element output signal amplifier, engines and tachometers. The classical system of indirect stabilization is reviewed, its mathematical description is made. A new precision sensitive element for the information and measurement system of weapon stabilization is suggested, the principle of its performance is introduced. Constructive methods of measurement accuracy improvement in the new sensitive element are analyzed. A simulation of the new sensitive element performance influenced by the external disturbances is carried out.

scholarly journals Вплив числа електродних пар на похибку електрохімічного давача поляризаційного опору для вимірювання шидкості атмосферної корозії

2020 ◽  
Vol 140 (6) ◽  
pp. 112-124
Author(s):  
С. О. Осадчук ◽  
Л. І. Ниркова ◽  
О. І. Букет
Keyword(s):  
Measurement Error ◽  
Corrosion Rate ◽  
Polarization Resistance ◽  
Sensitive Element ◽  
Aluminum Substrate ◽  
Atmospheric Conditions ◽  
Electrochemical Polarization ◽  
Sensing Element ◽  
Anodized Aluminum ◽  
Tight Contact

Investigate the influence of the number of electrode pairs of multi-electrode co-surface electrochemical polarization resistance sensors on the error of measurement of polarization resistance, and, accordingly, on the corrosion rate under atmospheric conditions. Method of polarization resistance. Determination of the contact area of electrodes with the aluminum substrate by the method of obtaining a print on a flat surface. Graphical modeling of the contact surface of the sensing element from the steel electrodes to the anodized aluminum substrate. Investigation results of the influence of the electrode pairs number of multielectrode cosurface electrochemical polarization resistance sensor, sensing element of which is steel-made and is located on the thermoconductive anodized aluminum substrate, on the measurement error of corrosion rate in atmospheric conditions are presented. It was shown that in determining of the corrosion rate by polarization resistance method the increasing of the electrode pairs number of sensor from one to four increases the reproducibility of measurement results and their convergence with the gravimetric data. Taking into account the form of prints of four-pair sensitive element, the area of surface contact of sensitive element of eight-pair sensor with aluminum substrate was graphically simulated. It was taken into account during modeling, that the design feature of the sensor is a possibility of full contact of one pair of the electrodes with the substrate, which explains the reason of measurement error increasing with increasing the number of electrodes’ pairs. Increasing the pairs number from one to four and then to eight decreases the part of surface of sufficiently tight contact of sensitive element with aluminum substrate from 100% to  50% and further up to 30 %. The extreme dependence of the measurement error on the number of electrodes pairs due to the increasing area of the working surface of the electrodes and reducing the area of tight contact with the aluminum heat-conducting base was revealed. It was found that four electrodes pairs for the presented sensor design is optimal. It was established that the reason of increasing of the error of polarization resistance measurement under atmospheric conditions and, accordingly, the corrosion rate, by using the electrochemical multi-electrode co-surface sensors of polarization resistance under increasing the electrode pairs number (from one to eight) is the decreasing in the surface part of a sufficiently dense contact of the sensitive element (about two or three times). Another tendency that leads to decreasing in error is decreasing in the error of setting the corresponding polarization while increasing the total area of the electrodes. The extreme dependence of this error on the number of electrode pairs with a minimum for a four-pair sensor is shown. The problem of uncontrolled variation of the measurement error by using the polarization resistance sensor of the considered construction was solved and the optimal number of electrode pairs (four) was determined. Using such of a sensor will allow to evaluate the corrosivity of the atmospheric air environment with respect to the responsible metal structures and their corrosion state in local corrosion-dangerous places with stable and minimal error.

Resistive Heating of a Shape Memory Composite: Analytical, Numerical and Experimental Study

2021 ◽  
Author(s):  
Clara Andrea Pereira Sánchez ◽  
Maxime Houbben ◽  
Jean-François Fagnard ◽  
Philippe Laurent ◽  
Christine Jerome ◽  
...  
Keyword(s):  
Steady State ◽  
Shape Memory ◽  
Temperature Dependence ◽  
Electric Current ◽  
Multiwall Carbon Nanotubes ◽  
Resistive Heating ◽  
Constant Power ◽  
Thermo Electric ◽  
Steady State Temperature ◽  
Analytical Expressions

Abstract This work investigates in detail the Joule resistive heating phenomenon of electroactive Shape Memory Composites (SMC) when an electric current is injected at constant power. The SMC is a covalent poly(ε-caprolactone) network filled with 3 wt% of multiwall carbon nanotubes. The resistive heating of the SMC is studied by means of surface temperature measurements, analytical formulas and a coupled 3D thermo-electric numerical model. Analytical expressions are derived for the 2D temperature distribution within a parallelepipedic SMC, either with constant or linearly-dependent electrical resistivity. These analytical expressions can be used to investigate the influence of geometrical and material parameters in the steady-state temperature and its distribution across the sample. The results also allow one to identify the parameters that are crucial for predicting the temperature rise due to resistive heating: the temperature dependence of the resistivity has little effect on the steady-state temperature, whereas the thermal conductivity plays a significant role. The time-dependent temperature is shown to be related to the particular temperature dependence of heat capacity. Furthermore, the presence of external objects (clamps or grips) used during the shape memory cycle must be taken into consideration for a certain temperature to be reached since they result in a lower steady-state temperature and a slower resistive heating phenomenon. With the findings presented in this work, accurate resistive heating can be predicted for a SMC upon the injection of an electric current at constant power.

SEISMOACOUSTIC SIGNALS PROCESSING FOR EXTENDING OF THE INFORMATIVITY OF FIBER-OPTICAL SENSITIVE ELEMENTS

2021 ◽  
pp. 117-128
Author(s):  
I. V. Denisov ◽  
A. E. Sonin
Keyword(s):  
Sensitive Element ◽  
Optical Sensing ◽  
Acoustic Signals ◽  
Sensing Element ◽  
Optical Measuring ◽  
Fiber Optical ◽  
Measuring Network ◽  
Acoustic Component

The principles of recording and processing of the combination of seismic and acoustic signals from single intruder by means of the underground fiber-optical sensing element are given in this article. It shows distinctive informative features of the signals. They complement known features in terms of acoustic component. The novelty of the work is combining the processing of seismic and acoustic signals. The interferometric fiber-optical measuring network is used as distributed fiber-optical seismic acoustic sensitive element.

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