The paper studies radiomeasuring device with a frequency output signal based on a pyroelectric primary converter. The frequency converter of optical radiation is designed using a bipolar transistor structure with a negative differential resistance and a pyroelectric sensitive element. A dynamic mathematical model of the frequency radiomeasuring converter has been developed which enables to determine the value of voltage or current at any point in the circuit at any particular time under the action of optical radiation in the region of infrared light. Analytical expressions for the transfer function and the sensitivity equation have been obtained. The sensitivity of the developed device is 20 kHz/μW/cm2.
Method of structural-functional organization of high speed buffer devices on the base of push-pull current amplifiers is considered. The importance and practical expediency of the creation of such types of voltage buffers for obtaining the low error of linearity and high operation speed is substantiated. Push-pull voltage buffers with the input amplifying stages and input current compensation are considered and analyzed. Analytical relations, describing static transfer characteristic, taking into account the circuit core parameters, are given. The components, leading to the linearity error occurrence are determined, ways of its reduction are shown. Voltage buffers with the decreased output resistance are suggested, for this purpose, push pull DC amplifiers are additionally introduced in the circuit, they have profound negative feedback. Computer simulation of the static and dynamic characteristics of the suggested schemes of the voltage buffers has been carried out, the comparative analysis of the results obtained has been performed, the possibility of the construction of high speed buffer devices on the base of push pull current amplifiers has been proved.
A tool has been proposed that allows rapid analysis to measure relative humidity during experimental research on the decomposition of municipal solid wastes for the development of highly efficient garbage trucks as the main link in the structure of machines for the collection and primary processing of municipal solid wastes. The structural scheme of the device for measuring relative humidity is given. A block diagram of the microcontroller control program algorithm for measuring relative humidity has been developed. The main characteristics of the proposed device are given. Calibration and experimental tests to measure the relative humidity of municipal solid wastes were conducted. As a result of the experimental studies presented in the work, the reliability of the measured parameter is confirmed.
Terms of operation of complex technical systems depend, first of all, on their technical condition, the level of which is determined by the capital class, service life and operating conditions. In turn, operating conditions are characterized by the presence of various types of loads, mechanical stresses caused by operational operations, as well as due to weather and climatic influences. Constant excess of permissible stresses can lead to the destruction of structures. Therefore, the continuous control of mechanical stress in the building is a factor in preventing not only economic losses, but also human casualties. The classification of methods of non-destructive control of mechanical stresses for metallic shutters of hydraulic engineering structures has been developed, a critical analysis of each method has been carried out, positive aspects and drawbacks of each method have been presented, as well as a relative change in residual-magnetized metal sample after application and removal of compressive stresses has been analyzed. The proposed work focuses on the search for new informative parameters based on the study of patterns of change in magnetic properties, on the development of new methods and means of measurement, in particular, with the involvement of several parameters in order to improve the accuracy and reliability of the measurement, significantly expand their capabilities.
Was reviewed the prospect of creation of resistance temperature detector based on the RL-diode generator of deterministic-chaotic oscillations for the increasing of sensitivity of the measuring instrument. Was conducted the researches of the scheme of RL-diode generator of deterministic-chaotic oscillations and was proposed to use synchronous detector for measuring output signal conversion of RL-diode generator of deterministic-chaotic oscillations, what allowed to decrease the effect of failure on the converter, were built schedules of dependency of output voltage from the temperature and schedules of the sensitivity.
Today, methane sensors find applications mostly in safety alarm installations, gas parameters detection and air pollution classification. Such sensors and sensors elements exists for industry and home use. Under development area of methane sensors application is dedicated to ground gases monitoring. Proper monitoring of soil gases requires reliable and maintenance-free semi-constant and longtime examination at relatively low cost of equipment. The sensors for soil monitoring have to work on soil probe. Therefore, sensor is exposed to environment conditions, as a wide range of temperatures and a full scale of humidity changes, as well as rain, snow and wind, that are not specified for classical methane sensors. Development of such sensor is presented in this paper. The presented sensor construction consists of five commercial non dispersive infra-red (NDIR) methane sensing units, a set of temperature and humidity sensing units, a gas chamber equipped with a micro-fan, automated gas valves and also a microcontroller that controls the measuring procedure. The electronics part of sensor was installed into customized 3D printed housing equipped with self-developed gas valves. The main development of proposed sensor is on the side of experimental evaluation of construction reliability and results of data processing included safety procedures and function for hardware error correction. Redundant methane sensor units are used providing measurement error correction as well as improved measurement accuracy. The humidity and temperature sensors are used for internal compensation of methane measurements as well as for cutting-off the sensor from the environment when the conditions exceed allowable parameters. Results obtained during environment sensing prove that the gas concentration readings are not sensitive to gas chamber vertical or horizontal position. It is important as vertical sensor installation on soil probe is simpler that horizontal one. Data acquired during six month of environment monitoring prove that error correction of methane sensing units was essential for maintenance free sensor operation, despite used safety procedures.
The work includes using a brushless direct current motor ventilator as a machine which fills a container where methane sensor is researched. The main issue is to choose the best controlling method and implement it to self-made driver of the motor.
KEYWORDS: Systems modeling, Instrument modeling, Mobile devices, Air contamination, Fuzzy logic, Roads, Data modeling, Measurement devices, Video, Mathematical modeling
The analysis of modern information measuring systems (IMS) for identification model parameters of the air pollution is carried out. That allows to increase the accuracy of this identification due to their complex application. The known model based on the fuzzy knowledge base was adapted to this task. It is specified how the offered IMS can increase the accuracy of the parameters identification. The results of the experiment with the use of the offered IMS in Vinnytsia city presented in the paper.
Large area SiC photodiodes find applications in optoelectronic sensors working at special conditions. These conditions include detection of UV radiation in harsh environment. Moreover, the mentioned sensors have to be selective and resistant to unwanted signals. For this purpose, the modulation of light at source unit and the rejection of constant current and low frequency component of signal at detector unit are used. The popular frequency used for modulation in such sensor is 1kHz. The large area photodiodes are characterized by a large capacitance and low shunt resistance that varies with polarization of the photodiode and can significantly modify the conditions of signal pre-amplification. In this paper two pre-amplifiers topology are analyzed: the transimpedance amplifier and the non-inverting voltage to voltage amplifier with negative feedback. The feedback loops of both pre-amplifiers are equipped with elements used for initial constant current and low frequency signals rejections. Both circuits are analyzed and compared using simulation and experimental approaches.
Technology, characterization and in particularly modeling of 4H-SiC photodiode have been presented in this paper. Modeling and simulation has been performed using PSPICE environment. Comparison of simulation with real results for electrical characteristic (I-V) of circular SiC photodiodes has been also presented.
Multiparametric capillary sensors are used for examination of liquids. The measurements results from such sensors are data from time series measurements taken during the movement of the fluid inside the capillary. The truthful characterization requires simultaneous measurements at different capillary points or performed with different techniques or specification. Points and tracks of time series can be analyzed simultaneously. Such analysis performed by trained human operators is time consuming and sometimes not precise because of slow signals levels variations resulting from device imperfection, and fast variations resulting from the presence of noise. The paper presents result of software characteristic data detection from a two-channel capillary sensor. One channel is for the reflected signal measurement; the other channel is for sensing of the scattered signal. The fluid movement inside the capillary is forced by local heating. The software analysis allows the classification of diesel and biodiesel fuel by their content on the base of the slopes of signals manifestation. Obtained results show that the automated analysis of the differences between two simultaneous channels of signals provides more precise data than those obtained from independent time series analysis.
The time series sequence of data readings are the input for computer aided analysis of signal from the multiparametric
optical capillary sensor. The time series signals have characteristic points and forms. Their analysis by trained human
operators is time consuming and sometimes lacks of precision because of the presence of signal noise. The noises can be
mostly rejected with advanced electronic signal processing, but the output analog signal is often modified by the
electromagnetic environment and by the noise generated by electronic elements. We propose and analyze an algorithm
that can be used as an automatic detector of characteristic points and form of the time series signals that are produced by
the measuring head and the analog electronic units of the biodiesel fuel quality test sensor.
This paper provides an overview of the process of 4H-SiC pn junction fabrication and characterization. The samples used in this study were fabricated in a resistively heated horizontal hot-wall Chemical Vapor Deposition reactor. The homo-epitaxial layers were grown on commercially available 4H-SiC substrates (Cree). In order to obtain p-type epilayers, they were intentionally doped with aluminum. In this work, we present our recently developed 4H-SiC pn junctions fabrication and characterization results. The ohmic contacts were formed using evaporation, etching, lift-off and high temperature annealing. Current-voltage characteristics of the devices were demonstrated.
This paper describes the construction, fabrication and properties of large-area ultra violet detector that is transparent in the visible range. The device was made on n-type 4H SiC substrate with a double epitaxial layer in which aluminum was implanted to form a p-n junction close to the surface, and a SiO2 layer was formed for passivation, without a guard ring. The design of the top and bottom electrodes of 4mm diameter UV sensitive area allows not less than 20% visible range transmission. This transmission was measured across sensitive area of examined devices and was only 5% lower than that of the substrate before implantation and electrodes deposition.
Silicon Carbide (SiC) photodiodes have been proposed in recent years for ultraviolet (UV) light detection because of their robustness even in harsh environments, high quantum efficiency in all the UV range (200nm-400nm), excellent visible and infra-red blindness excluding UV filters implementation, low dark current and high speed. 4H-SiC has a bandgap three times larger (3.26eV) than Si and, thus, SiC detectors should have much higher sensitivity than Si detectors. In this paper, we present an overview of results on 4H-SiC p-i-n junctions fabrication and characterization. We used implantation technique to obtain p-region of the investigated structure. The ohmic contacts were formed using evaporation, etching and lift-off. Current-voltage, contact resistance and electroluminescence are the main characteristics of the presented devices. All the diodes showed excellent rectification with leakage current density of less than 10-9A/cm2.
KEYWORDS: Analog electronics, Calibration, Amplifiers, Transistors, Surface plasmons, Control systems, Distortion, Diodes, Digital electronics, Patents
The paper analyzes the static and dynamic characteristics of the analog components of the self-calibrating multibit ADC with weight redundancy. The mathematical expressions for an estimation of the analog components characteristics are specified. The guidance on the practical implementation of the analog components of the self-calibrating multibit ADC with weight redundancy is also provided. The paper proposes to use dc amplifiers that are built on the base of push-pull symmetrical structures for those needs.
This paper describes an application of curvelet transform analysis problem of interferometric images. Comparing to two-dimensional wavelet transform, curvelet transform has higher time-frequency resolution. This article includes numerical experiments, which were executed on random interferometric image. In the result of nonlinear approximations, curvelet transform obtains matrix with smaller number of coefficients than is guaranteed by wavelet transform. Additionally, denoising simulations show that curvelet could be a very good tool to remove noise from images.
Flame radiation intensity and its changes in time domain deliver the quickest and straight information of a combustion process. We have compared combustion of coal-biomass mixture and reference coal through flame image analysis. The aim of the research was finding flame's shape features, that could point to a state of unstable combustion, for the fuels being considered. Several combustion tests have been made in a laboratory stand for pulverized coal mixed with paper sludge (10%) with variable coal flow. The stand was equipped with scaled down (1:10) low-NOx burner. Flame images were recorded by a standard monochrome camera and captured by a frame grabber. After conversion to black-and-white images, changes of some shape parameters such as flame area, its horizontal and a vertical dimensions and shape coefficient have been investigated.
This paper presents review of optical radiation measurement method in combustion process. Analysis and comparison of different methods is described and some applications in coal combustion boilers are shown. Such sensors can detect presence of target molecule, measure concentration ratio of two molecules and quantitatively measure the concentration.
The flame monitoring system is intended to use in industrial condition for controlling pulverized coal combustion in power boiler. Placing the fiber-optic probes close to the each burner, one can obtain detailed information of the coal combustion process within the single burner. In order to enhance flame-monitoring system sensitivity for detection of fuel's composition changes, we have measured flame emission spectra.
Artificial neural networks (ANN), or connectionist classifiers, are massively parallel computation systems that are based on simplified models of the human brain. Their complex classifications capabilities, combined with properties such as generalization, fault-tolerance and learning make them attractive for a range of applications that conventional computers found difficult. One of the possible neural net applications is an analysis of high dimension data sets. Thanks to mentioned above classifications capabilities, net output signals are low-dimension representations of inputs where each output can represented some input signal feature. In this paper we present the new algorihtm of multivariate data classification. The algorithm based on modified counterpropagation neural network. The main goal of our research as to develop a new classifier architecture which reduces the required number of interconnection in a hidden layer as well as output layer. That allows easier hardware implementation of proposed algorithm.
In this article we compare compression of flame pulsation signals based on Fourier transform, wavelet transform and wavelet packet transform. The results show efficiency of compressing based on cumulative energy of the same number of coefficients.
Burning pulverized coal in power boilers causes considerable emission of atmospheric pollution. In order to decrease it the combustion process itself has been modified, however at the cost of side effects like: an increased level of unburned coal particles in the ashes. There are tens of burners in a single power boiler and emission level measurements are made in a flue gas duct, so the control based on such averaged and heavily delayed values often results ineffective. The neural controller of the pulverized coal burner attempts to resolve these problems. The clue is the utilization of the fiber-optic system for monitoring of chosen zone of flame developed in Department of Electronics of Technical University of Lublin in subordinate control loop. The article contains a description of controlled system and optical fiber measurement system as well as the idea of new control structure and initial models.
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