Wyniki 1-10 spośród 15 dla zapytania: authorDesc:"Oleksandra HOTRA"

Multirange code-controlled active resistance imitator

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The influence of connecting wires resistance and contact resistance of commutating elements on the accuracy of resistance imitators has been investigated. A new combined technique of setting the range of imitated resistance, as well as schematic design of an active resistance imitator independent of the influence of wire resistance and commutating elements is proposed. This construction allows the transfer of standard unit measures of resistance, with standard accuracy, to remote points even for low nominal values of standard resistances. Streszczenie. Badano wpływ rezystancji przewodów łączeniowych oraz rezystancji załączonych elementów komutacyjnych na dokładność odtworzenia rezystancji w aktywnych imitatorach rezystancji sterowanych kodowo. Opisano kombinowany sposób nastawiania zakresów imitowanej rezystancji oraz układ aktywnego imitatora rezystancji niezależnego od wpływu rezystancji przewodów i przełączników, który pozwala na przekazywanie wzorcowych miar rezystancji (nawet niskich) na odległość z zachowaniem wysokiej dokładności. (Wielozakresowy sterowany kodowo aktywny imitator rezystancji) Keywords: code-controlled resistance standard, active resistance imitator, supplementary voltage divider. Słowa kluczowe: wzorzec rezystancji sterowany kodowo, aktywny imitator rezystancji, pomocniczy dzielnik napięcia. Introduction In advanced modern industry an intensive growth of implementations of computerized systems for controlling technological processes is observed. The structure and composition of these systems can be modified during their operation; that often requires some settings of the system to be altered. Large quantities of transducers used in such systems (e.g. some 400 resistive temperature sensors are set only on one block of a nuclear power station) require periodical checking of their functioning under working conditio[...]

Microprocessor temperature meter for dentistry investigation

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The peculiarities of measuring the temperature on the root surface of a tooth by means of thermoelectric transducers during obturation are described. Linearization methods for transfer functions of thermoelectric transducer within the range of interest in dentistry investigation: from 20°C to 60°C are discussed. The scheme of microprocessor temperature meter with the basic relative measurement error less than 1% is presented. Streszczenie. Opisano uwarunkowania pomiarów temperatury na powierzchni korzeni zębów za pomocą czujników termoelektrycznych podczas obturacji. Rozpatrzono metody linearyzacji funkcji przetwarzania czujników termoelektrycznych dla zakresu temperatury od 20°C do 60°C, istotnego w badaniach stomatologicznych. Przedstawiono układ mikroprocesorowego miernika temperatury, którego błąd względny podstawowy wynosi poniżej 1%. (Mikroprocesorowy miernik temperatury do badań stomatologicznych). Keywords: obturation, thermocouple, temperature meters, linearization. Słowa kluczowe: obturacja, termopara, mierniki temperatury, linearyzacja. Introduction During many years of endodentistry developement, various methods and materials for filling the root canal were applied. The most common current technique of filling the root canals uses gutta-percha. For better filling of root canal, techniques operating with heated gutta-percha cannot fill the lateral and apical canals, and the cavities can be the origin of inflammatory processes in periodontal tissues and of destruction of bone tissue. The softening of gutta-percha by heat is popular technique, but the use of large amount of heat can be dangerous as the excessive heat can be transferred to surrounding periodontal tissues. The elevated level of heat above 47°C kept for a longer time interval inflict harm on the teeth tissue and bone. For establishing the technique of filling the root canals with heated gutta-percha, it is necessary to evaluate the temperature on the root sur[...]

Cold-junction temperature compensation of thermoelectric transducers

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Przeanalizowano właściwości układów mostkowych zależnych od temperatury, służących do kompensacji temperatury spoiny odniesienia termopary z oddzielnymi źródłami napięcia lub prądu. Wykazano, że dla wąskiego zakresu zmian temperatury spoiny odniesienia można osiągnąć poprawę efektywności układów kompensacyjnych za pomocą przesunięcia charakterystyk tych układów, natomiast dla szerokiego zakresu zmian temperatury można osiągnąć poprawę efektywności układów kompensacyjnych wykorzystując źródło napięcia zależne od temperatury, wykazujące dodatni współczynnik temperaturowy. Proponowany układ pozwala osiągnąć zmniejszenie błędu bezwzględnego kompensacji do wartości nie przekraczających 0,1°C dla różnych typów termopar. (Kompensacja temperaturowa spoiny odniesienia w przetwornikach termoelektrycznych). Abstract. In this paper, the properties of temperature-dependent bridge-type circuits employed for the cold-junction compensation - for the bridge circuits excitation from separate constant voltage or constant current source - are discussed. The considerations have been focused on the techniques of improving the effectiveness of the compensating circuits. It has been found that over a narrow range of the cold-junction temperature variations the effectiveness of the compensation circuit can be improved by the shift of the circuit characteristic; across a wide range of the temperature variations the improvement in the effectiveness of the compensation circuit can be achieved by using a temperature-dependent constant voltage source which has positive temperature coefficient. The proposed compensating circuit allows reducing the absolute compensation error to less than 0.1°C for different types of thermocouples. Słowa kluczowe: termopary, pomiary temperatury, układy kompensujące spoin odniesienia. Keywords: thermocouples, temperature measurements, cold junction compensation circuits. Introduction Temperature is the most commonly measured quantity tha[...]

A device for thermal conductivity measurement based on the method of local heat influence

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The requirements for the design of portable device for measuring thermal conductivity based on the method of local heat influence are theoretically formulated. The influence of the heat exchange with surrounding environment, the contact thermal resistance between the probe and the surface is discussed. Also, the influence of the size of heat influence zone on the accuracy of measurement of the thermal conductivity of materials is considered. Streszczenie. Sformułowano teoretyczne podstawy projektowe dla przenośnych urządzeń do pomiaru przewodności cieplnej materiałów metodą lokalnego wpływu ciepła. Opisano wpływ wymiany cieplnej z otoczeniem, rezystancji cieplnej kontaktu sondy z powierzchnią materiału badanego. Przeanalizowano również wpływ rozmiaru powierzchni strefy wnikania ciepła na dokładność pomiaru przewodności cieplnej materiałów. (Teoretyczne podstawy projektowe dla przenośnych urządzeń do pomiaru przewodności cieplnej materiałów metodą lokalnego wpływu ciepła) Keywords: thermal conductivity, thermal conductivity measurements Słowa kluczowe: przewodność cieplna materiałów, pomiary przewodności cieplnej Introduction In general, it is necessary to determine the coefficient of thermal conductivity of materials not only in stationary laboratory conditions, but also in operating conditions using fast methods. For these purposes, the contact transient methods for thermal conductivity measurements which use plane or linear heating element: hot disk [1-2], hot wire [3], hot strip [4-5]; and a method of measurement of thermal conductivity based on inverse solution for one-dimensional heat conduction [6] are widely applied. All these methods have the disadvantages described in [7]. A special method for thermal conductivity measurement of low density insulating materials was proposed in [7]. The purpose of this work was to develop a new device, based on the steady state method of local heat influence, which is characterized not onl[...]

Compensation bridge circuit with temperature-dependent voltage divider

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The bridge circuit with temperature-dependent voltage divider for compensation of cold-junction temperature of thermocouple is described. The proposed circuit allows reducing the influence of cold-junction to less than 0,1С for thermocouples of the K-type (chromel - alumel) and L-type (chromel - copel). Streszczenie. W artykule opisano mostkowy układ kompensacji wolnych końców termopary zawierający zależny od temperatury dzielnik napięcia. Opracowany układ pozwala zmniejszyć wpływ zmian temperatury wolnych końców na wynik pomiaru poniżej 0,1С dla termopar typu K (chromelalumel) i typu L (chromel-kopel). (Mostkowy układ kompensacji wolnych końców termopary zawierający zależny od temperatury dzielnik napięcia) Keywords:. thermocouple, temperature-dependent voltage divider, cold-junction compensation Słowa kluczowe: termopara, dzielnik napięcia zależny od temperatury, kompensacja wolnych końców termopary Introduction The temperature is widely measured in modern industry, scientific experiments, materials testing etc. - practically all fields of human activity are connected with temperature measuring and control. Thus the temperature is the most often measured physical quantity. The increase in accuracy of the temperature measurement drives the production quality improvement. For low and medium range temperature measurements, various types of temperature transducers such as thermoresistorsor, thermocouples etc. are employed. If thermocouples are employed, it is necessary to take into account the influence of cold-junction temperature of the thermocouple on the measurement accuracy [1]. For compensation of the influence of cold-junction temperature, the thermostatting devices or compensation circuits are used [2, 3]. Analo[...]

Approximation of sensor output data using Chebyshev-Laguerre polynomials

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The integral Laguerre transform is generalized by introduction of scale factor and argument to arbitrary power. The possibility of usage of such transforms for approximation of sensor output data, filtration of the signals in linear filter models and numerical determination of signal derivatives is described. Streszczenie. Całkowa transformata Laguerre’a może być uogólniona za pomocą wprowadzenia współczynnika skalowania i argumentu w dowolnej potędze. Opisano wykorzystanie takich całkowych transformat do aproksymacji danych wyjściowych sensorów, filtracji sygnałów w liniowych modelach filtrujących i wyznaczenia pochodnych dla sygnałów. (Aproksymacja danych wyjściowych sensorów za pomocą transformaty Czebyszewa-Laguerre’a) Keywords: generalized Laguerre transform, sensor output data approximation Słowa kluczowe: uogólniona transformata Laguerre’a, aproksymacja danych wyjściowych sensora Introduction The application of sensors for measuring the parameters of oscillating processes requires to develop the appropriate mathematical software for processing the gathered data sets. The basis for the solution of such problems is the spectral representation of the functions in orthogonal bases [1-2]. A comparative analysis of the functions in Fourier, Haar, and Walsh bases has shown that not all criteria imposed on the solutions are satisfied. Hence, the methods in other orthogonal bases such as Jacobi, Chebyshev-Laguerre, and Hermite are developed [3-5]. It seems reasonable to use the Chebyshev-Laguerre polynomials Ln (t),   1 for research on the oscillating processes in time. The disadvantage of these polynomials is the exponential increase with time at high orders. This disadvantage limits the research area in which the polynomials are used because there are calculation difficulties emerging when the summation of appropriate series for high values of the time variable t is performed. T[...]

Improvement of dynamic characteristics of thermoresistive transducers with controlled heating DOI:10.15199/48.2019.05.27

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Microprocessor sensory systems as a component of information and communication technologies are an integral attribute of human society at the present stage. The sphere of sensory systems application is constantly expanding. Special place belongs to sensors of temperature and humidity. These sensors are widely used in automated control systems at food and light industry, agriculture, oil and gas pipelines, medical and environmental monitoring systems [1-5]. Measuring the humidity and temperature of air and industrial gases is important for ensuring the quality of final products. For example, changing the temperature of gas in gas pipelines can cause condensation of water vapour, which leads to negative consequences, such as corrosion, the formation of aggressive chemicals, etc. Changing of temperature also influence the characteristics of different sensors, for example, of capacitive sensors [6]. In order to measure humidity the sensors based on polymeric or ceramic materials that are sensitive to humidity are used [7]. The measurement of low humidity (up to 20% RH) was not sufficiently investigated, and was accompanied with difficulties due to significant errors in the nonlinearity of humidity sensors. Modelling of polymer-based capacitive humidity sensors carried out in [8] allowed to explain the nature of nonlinearity and suggests a logarithmic relationship between the relative humidity and the output value of the sensor. The combination of the results of researches of humidity sensors (in particular their accuracy and calibration [9-10]) and temperature sensors (in particular linearization of the transfer function of thermoresistive transducers [11-12], cold-junction compensation in thermocouples [13]) will allow for comprehensive control of the parameters of technological processes. It is advisable to use integrated temperature and humidity sensors in which temperature compensation can improve the accuracy of humidity [...]

Using the test method for optimization the Peltier device for achievement superconducting transition temperatures

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A new method for determining electric and thermal characteristics of Peltier devices is analyzed with the aim of optimization of Peltier devices. Obtained results give the possibility to optimize thermoelectric cooler systems to reach most efficient operating state and to achieve the lowest possible temperature. In optimized by proposed method four stage Peltier cooling cascade the achieved temperature could be near to the superconducting transition temperature of HgBa2CaCu2O6+δ. Peltier device is not damaged during the test process and still can be used. Streszczenie: W artykule przeanalizowano nową metodę wyznaczania elektrycznych oraz termicznych parametrów ogniw Peltiera. Otrzymane wyniki dają możliwość optymalizowania chłodziarek termoelektrycznych w celu osiągnięcia najbardziej efektywnego punktu pracy. W czterostopniowej chłodziarce termoelektrycznej zoptymalizowanej przy użyciu proponowanej metody otrzymana temperatura może być bardzo bliska temperaturze nadprzewodnictwa HgBa2CaCu2O6+δ. Badany element Peltiera nie ulega uszkodzeniu podczas testu i może być dalej używany. (Wykorzystanie metody badań ogniw Peltiera do optymalizacji ich punktu pracy w celu osiągania temperatur nadprzewodnictwa) Keywords: thermoelectric coolers, thermoelectric properties, Peltier device, test method of Peltier device, superconductor temperature Słowa kluczowe: chłodziarki termoelektryczne, moduł termoelektryczny, charakterystyki ogniw Peltiera Introduction Thermoelectric modules are widely used in military equipment, aeronautics and industry. They owe their popularity to simple construction without any mechanical elements, that increases the reliability. Peltier cooling devices have special place in superconductor electronics. Superconducting microelectronic circuits are largely miniaturized and only a small cooling power of the order of milliwatts is needed. In multi-stage thermoelectric coolers the temperature as low as 149 K can be reac[...]

Optimal control of copper concentrate blending and melting based on intelligent systems DOI:10.15199/48.2016.08.34

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The possibilities of use of intelligent systems in automation of production and technological processes are considered. The intelligent system for optimal control of copper concentrate blending and melting is developed. The paper presents the results of the investigation of the intelligent system for optimal control of copper concentrate blending and melting using neural network (Matlab NNTool), adaptive neuro-fuzzy (hybrid network Matlab Anfis) and fuzzy inference (Matlab Fuzzy Logic) modelling. Streszczenie. W artykule opisane zostały możliwości wykorzystania inteligentnych systemów sterowania w automatyzacji procesów produkcyjnych I technologicznych. Przedstawiony został system do optymalnego sterowania topieniem i wzbogacaniem koncentratu miedzi. W artykule przedstawiono również wyniki badań symulacyjnych przedstawionego systemu z wykorzystaniem sieci neuronowych (Matlab NNTool), rozmytych (sieć hybrydowa Matlab ANFIS) i logiki rozmytej (Fuzzy Logic) (Sterowanie optymalne procesem rozdrabiania i roztapiania wsadu miedzianego w oparciu o systemy inteligentne). Keywords: copper concentrates, charge, electromelting, modelling, intelligent control systems. Słowa kluczowe: koncentraty miedzi, wsad, roztapianie elektryczne, modelowanie, inteligentne systemy sterowania. Introduction The control of blending and melting of copper concentrates is conducted in conditions of information uncertainty connected with the complexity of physical and chemical processes. In this case, traditional control methods are not effective enough. Therefore, instead of traditional control methods the intelligent networks could be used. The intelligent networks are the most effective when the traditional calculations are time-consuming or physically inadequate. The use of intelligent models in control has several advantages: reducing of the amount of computation, the intelligent model is easier to understand than the equivalent mathematical model based on diff[...]

Synthesis of the configuration structure of digital receiver of NQR radiospectrometer DOI:10.15199/48.2018.07.14

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The study of physical properties of substances using pulsed electromagnetic radiation has become widespread in optical and radio wave spectroscopy. Pulsed Fourier spectroscopy of nuclear quadrupole resonance (NQR) is based on powerful radio frequency excitation pulses and the use of highly sensitive equipment [1-3]. In response to the short broadband δ-pulse, this method ensures the excitation of all resonance frequencies of the NQR spectrum. The method of detecting free induction decay signals (FID) requires a thorough analysis, since its implementation governs the accuracy of visualization of complex resonance spectra, especially when it comes to multi-pulse experiments. Recently, in the developed countries of the world, much work is in progress on the development of radiotechnical systems that are referred to collectively as Software Defined Radio (SDR) [4]. The essence of SDR technology is to use full digitization of the radio signal by high-speed analog-to-digital converter (ADC) with subsequent processing of the received data in digital form. In this case, the basic parameters of receivers and transmitters are determined by the software itself, rather than by the hardware configuration. The purpose of this work is to synthesize the configuration structure of the receive path of the NQR radiospectrometer, in which the SDR technology is chosen for the implementation of the quadrature detector with the filtration system and the suppression of quadrature reflections. Statement of the research task It is known that in the pulsed NQR, the FID signals are detected by transferring the resonance spectrum of width  to the low frequency (LF) range by subtracting the reference frequency ω0, which is close to the frequency of the resonating nucleus. The method for detecting FID signals which is partially considered in [5] requires a more thorough analysis, since its implementation governs the accuracy of visu[...]

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