Search

A self-oscillating parametric humidity sensor has been developed that implements the principle of "humidity-frequency" conversion into hybrid integrated circuit based on a microelectronic transistor structure with a negative differential resistance, in which the humidity-sensitive element is a resistor of the HR202 type. For the purposes of determining parameters self-oscillating parametric humidity sensor with frequency output a mathematical model has been developed that takes into account the effect of humidity on a sensitive resistive element, which is an integral element of the device. Based on the mathematical model, analytical expressions for the transformation function and the sensitivity equation are obtained. It is shown that the main contribution to the conversion function is made by relative humidity. The computer simulation and experimental studies of a self-oscillating parametric humidity sensor with a frequency output signal contributed to obtaining the main parameters and characteristics, such as the dependence of the generation frequency on changes in relative humidity in the range from 30% to 99%, the change in sensitivity on relative humidity, the dependence of the active and reactive components of the impedance in the frequency range from 50 kHz to 2 GHz; standing wave ratio, change in logarithmic magnitude and spectra of the output signal of a parametric humidity sensor with a frequency output signal in the LTE-800 Downlink frequency range. The obtained electrical characteristics confirm the operability of the developed device. The sensitivity of the developed self-oscillating parametric humidity sensor in the range of relative humidity change from 30% to 99% has a value from 332.8 kHz/% to 130.2 kHz/%.

A new magnetically sensitive element based on the synthesized semiconductor material has been developed. A method for the synthesis of a complex compound has been developed tetrakis-µ3-(methoxo) (methanol)-pentakis (acetylacetonate) (tricuprum (II), neodymium (III)) methanol (I). The scheme of arrangement of chemical bonds for this complex compound is offered. Conducted properties have been studied tetrakis-µ3-(methoxo) (methanol)-pentakis (acetylacetonate) (tricuprum (II), neodymium (III)) methanol (I) in compressed form in the temperature range 273 - 493 K showed that conductivity varies from 5.67 ∙ 10-14 (Ohm ∙ m)-1 at a temperature of 273 K to 1.06 (Ohm∙m)-1 at a temperature of 493 K. The experiment showed that in the temperature range 303 - 423 K resistivity of the pressed sample of the test material of compound (I) decreases from 2∙1010 Ohm∙m to 5 ∙ 102 Ohm∙m, ie the isolated compound is a semiconductor. In the developed magnetoresistor when changing the induction of the magnetic field from 10-3 to 200 mT, the resistivity varies from 3.12∙10-5 Ohm to 1.25∙10-2 Ohm∙m, and from 200 mT to 1 T, the resistivity varies from1.25∙10-2 Ohm to 0.3 Ohm. On the basis of the developed magnetically sensitive resistive element the circuit solution of the frequency transducer of a magnetic field is offered. The frequency transducer of the magnetic field is a hybrid integrated circuit consisting of a bipolar transistor and a gate gate transistor, which creates the preconditions for the creation of an autogenerator device, the feedback circuit of which includes a magnetically sensitive resistor based on tetrakis-µ3- (methoxo) (methanol)-pentakis (acetylacetonate) (tricuprum (II), neodymium (III)) methanol (I).The frequency of generation of the developed transducer increases the most in the range from 10-3 T to 0.2 T, and at a supply voltage of 5.0 V varies from 250 kHz to 600 kHz, and in the whole range of changes in magnetic field induction varies from 250 kHz to 750 kHz. The sensitivity of the developed device with frequency output for measuring the induction of the magnetic field is from 400 Hz/mT to 800 Hz/mT.

What if the SS as the main Nazi organisation responsible for the Holocaust produced a secret film about the persecution and murder of the European Jews during World War II? This essay discusses the possible production of a documentary film about the genocide, made by the perpetrators. In doing so, it challenges a set of assumptions that commonly opposes such an endeavour. By examining the various activities of private and official photographers and cameramen in the context of the deportation and extermination of the European Jews and by drawing on contemporary sources which hint at such a – now lost – film project, the essay examines the available evidence and investigates comparable footage, arguing that the gaze of the perpetrators has long been part of our collective visual memory of the Holocaust.

Based on the consideration of physical processes in a tunnel-resonant diode under the action of a magnetic field, the construction of an autogenerating magnetic field sensor with a frequency output signal is proposed. The use of devices with negative differential resistance makes it possible to significantly simplify the design of magnetic field sensors in the entire RF frequency range. Depending on the operating modes of the sensor, an output signal can be obtained in the form of harmonic oscillations, as well as in the form of pulse oscillations of a special form. The study of the characteristics of the magnetic field sensor is based on the complete equivalent circuit of the tunnel-resonant diode. The equivalent circuit takes into account both the capacitive and inductive properties of the tunneling resonant diode. The inductive component exists under any operating conditions, as a result of the fact that the current flowing through the device is always lagging behind the voltage that caused it, which corresponds to the inductive response of a tunnel-resonant diode.