FREQUENCY MANIPULATOR WITH MINIMUM SHIFT AND COHERENT DETECTOR

Предложены новые варианты частотного манипулятора и когерентного детектора с минимальным сдвигом. Упрощена схема манипулятора, выполненного на автогенераторе, к колебательному контуру которого параллельно подключается индуктивность или емкость (в зависимости от знака манипулирующего сигнала). Получена новая формула для оценки выигрыша в помехоустойчивости когерентного детектора перед некогерентным. In this article, new versions of a frequency manipulator and a coherent detector with a minimum shift are proposed. The manipulator is based on a self-oscillator, to the oscillatory circuit of which inductance or capacitance is connected in parallel (depending on the sign of the manipulating signal). A new formula is obtained for estimation of gain in noise immunity of coherent detector before non-coherent one.

Development of an electromagnetic device for studying the electrophysical properties of agricultural products

The problem of control and quality of agricultural products is relevant for agro-industrial production. To determine the quality indicators, for example, milk, various indirect methods are used, but they are complex, some require special preliminary preparation of the sample. We need methods that will meet the following requirements: simplicity, speed and mobility. The identification of the electrophysical properties of biological objects can become the basis for the development of an electromagnetic method that will meet the above conditions. The article considers processes based on a change in the voltage (output signal) of a parallel oscillatory circuit in which an inductive cell contains the studied agricultural products. (Research purpose) The research purpose is in developing a device for determining the electrophysical properties of biological objects, analyzing the results of the study, obtaining the dependences of the output signal of the resonant amplifier on the frequency of the generator. (Materials and methods) The article presents studies of the resonant processes occurring in the simplest parallel oscillatory LC circuit. The article analyses the effect on the output parameters of a parallel oscillatory LC circuit when its inductance changes by placing various substances in an inductive coil. (Results and discussion) The article presents a block diagram of an electromagnetic device for determining and studying the electrophysical properties of biological objects. The block diagram is implemented directly into an electromagnetic device. Authors created a program in the MATLAB package for processing the experimental data. Based on the results of processing, authors got frequency dependencies for various biological objects of agriculture. (Conclusions) The processing of an array of experimental data will allow us to determine the functional, statistical and logical dependencies between the output and input values of the presented device.

MATHEMATICAL SIMULATION OF A DEVICE WITH FREQUENCY OUTPUT FOR MEASUREMENT OF HUMIDITY

The device for measuring humidity with a moisture-sensitive resistive element HR202 has been developed. The self-generating transducer is designed as a hybrid integrated circuit based on a bipolar transistor VT1 and a field-effect two-gate transistor VT2. The negative differential resistance, which is formed by the parallel connection of the impedance with a capacitive component at the collector electrodes of the bipolar transistor VT1, the drain of the field-effect transistor VT2 and inductance L1, leads to the occurrence of electrical oscillations in the circuit. When exposed to moisture on the sensitive resistive element RW, the capacitive component of the impedance at the electrodes of the transistor structure changes, which causes an effective change in the frequency of the oscillatory circuit. On the basis of mathematical modeling of electrical characteristics, analytical expressions for the transformation function and the sensitivity equation are obtained. It has been experimentally established that an increase in the ambient temperature in the range of relative humidity W = 30 ÷ 85% leads to an expansion of the generation range of the autogenerating humidity transducer, as well as to an increase in the sensitivity of the device to the measured value. The generation range of the autogenerating humidity transducer at a temperature of T = 20 °C acquires a value of 823 kHz (the average value of the sensitivity is 16.18 kHz /%), and at a temperature of T = 50 °C – 1323 kHz (the average value of the sensitivity is 29.10 kHz / %). To confirm the theoretical results of circuit solutions developed device in the computer modeling of LTSpice modeling environment. The studies were carried out at different temperatures (20°C, 30°C, 40°C, 50°C) in the range of change in the resistance of the moisture-sensitive resistive element from 1750 kOhm to 2.1 kOhm, which corresponds to an increase in the value of the relative air humidity from 30 % to 90 %. The results of theoretical and experimental studies have shown that at the output there are periodic oscillations device for measuring the humidity rate which increases with increasing values ​​of relative humidity. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.

SOLVING THE PROBLEM OF ROAD AND RAIL TRANSPORT OBJECTS WEIGHING IN MOTION

The algorithm for processing data obtained from strain gauges during dynamic weighing of a railway or auto car passing through the weighing platform using the parametric identification method is considered. The model of the second-order oscillatory circuit is presented and the method for identifying its coefficients with the transformation to the Volterra integral equation of the 2nd kind is shown. An idealized simulation model of the oscillatory link is proposed, which allows to obtain the output signal shape depending on its coefficients and the input signal parameters. Using the results of simulation modeling, the effectiveness of the proposed identification algorithm for determining the input signal parameters is shown.

MATHEMATICAL SIMULATION OF A DEVICE WITH FREQUENCY OUTPUT FOR MEASUREMENT OF HUMIDITY

The device for measuring humidity with a moisture-sensitive resistive element HR202 has been developed. The self-generating transducer is designed as a hybrid integrated circuit based on a bipolar transistor VT1 and a field-effect two-gate transistor VT2. The negative differential resistance, which is formed by the parallel connection of the impedance with a capacitive component at the collector electrodes of the bipolar transistor VT1, the drain of the field-effect transistor VT2 and inductance L1, leads to the occurrence of electrical oscillations in the circuit. When exposed to moisture on the sensitive resistive element RW, the capacitive component of the impedance at the electrodes of the transistor structure changes, which causes an effective change in the frequency of the oscillatory circuit. On the basis of mathematical modeling of electrical characteristics, analytical expressions for the transformation function and the sensitivity equation are obtained. It has been experimentally established that an increase in the ambient temperature in the range of relative humidity W = 30 ÷ 85% leads to an expansion of the generation range of the autogenerating humidity transducer, as well as to an increase in the sensitivity of the device to the measured value. The generation range of the autogenerating humidity transducer at a temperature of T = 20 °C acquires a value of 823 kHz (the average value of the sensitivity is 16.18 kHz /%), and at a temperature of T = 50 °C – 1323 kHz (the average value of the sensitivity is 29.10 kHz / %). To confirm the theoretical results of circuit solutions developed device in the computer modeling of LTSpice modeling environment. The studies were carried out at different temperatures (20°C, 30°C, 40°C, 50°C) in the range of change in the resistance of the moisture-sensitive resistive element from 1750 kOhm to 2.1 kOhm, which corresponds to an increase in the value of the relative air humidity from 30 % to 90 %. The results of theoretical and experimental studies have shown that at the output there are periodic oscillations device for measuring the humidity rate which increases with increasing values ​​of relative humidity. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.

Proportional-Integral-Derivative Control of Four-Variable Chaotic Oscillatory Circuit Based on DNA Strand Displacement

DNA molecular computing based on DNA strand displacement (DSD) technology is a potential computing model. Different functions can be realized by constructing DNA strand displacement analog circuit and analyzing its dynamic characteristics. In this paper, exploiting chemical reaction networks (CRNs) as the middle layer, a new chaotic oscillation circuit is constructed via DNA strand displacement and controlled by PID controller. The design of four-variable chaotic oscillatory circuit requires the combination and cascade by five DNA reaction modules. Based on the theory of stability and design principle of controller, the proportion terms, integration terms, and differentiation terms are added to chaotic oscillatory circuit for implementing PID controller. PID controller is implemented by five DNA reaction modules to stabilize the chaotic oscillation circuit. The validity of reaction modules circuit with their corresponding DSD reaction modules and controller is verified by visual DSD and Matlab. The PID controller may have better performance than PI controller, and it is an extension of PI controller.

A folder mechanism ensures size uniformity among C. elegans individuals by coupling growth and development

Animals increase by orders of magnitude in their volume during development. Hence, even small differences in the growth rates between individuals could generate large differences in their adult body size. Yet, such volume divergence among individuals is usually not observed in nature.We combined theory and experiment to understand the mechanisms of body size uniformity. Using live imaging, we measured the volume growth of hundreds of individuals of C. elegans over the entire span of their postembryonic development. We find that C. elegans grows exponentially in volume with a coefficient of variation of the growth rate of ∼7%, but that individuals diverge much less in volume than expected from this heterogeneity. The mechanism counteracting size divergence does not involve size thresholds for developmental milestones. Instead, an inverse coupling of the growth rate and the duration of development produces a constant volume fold change per larval stage.The duration of larval stages of C. elegans is determined by the period of a developmental oscillator. Using mathematical modelling, we show that an anti-correlation between the growth rate and the oscillatory period emerges as an intrinsic property of a genetic oscillator. We propose that the robustness of body volume fold change is a hard-wired characteristic of the oscillatory circuit and does not require elaborate mechanisms of size control by cellular signalling. Indeed, the coupling of growth and development was unaltered by mutation of canonical pathways of growth control. This novel concept of size homeostasis may broadly apply to other multicellular systems controlled by genetic oscillators.

Dynamics of the generator with three circuits in the feedback loop. Multistability formation and transition to chaos

Background and Objectives: Studying the dynamical mechanisms of the emergence of nonlinear phenomena that are characteristic for multimode self-oscillating systems consisting of interacting oscillators and an ensemble of passive oscillators or representing active nonlinear systems with complex feedback channels is an important urgent task. The simplest example of a self-oscillating system with a complex feedback is the well-known classical van der Pol oscillator with an additional linear oscillatory circuit included in the feedback channel. We investigate the behavior of the multimode system increasing the number of oscillatory circuits in the oscillator’s feedback loop. The research in this paper can help to better understand the mechanisms of multistability formation in infinite-dimensional self-oscillating systems such as a generator with delayed feedback and a generator with distributed feedback. Materials and Methods: The system equations were derived for the electronic scheme of the self-oscillating system. To describe the existing dynamic modes by numerical simulation methods, the projections of the phase portraits and the Poincare sections were obtained. To study the mechanisms of formation of multistable states, the bifurcation analysis methods were used. Results: It was found that the mechanism underlying the multistability formation is based on a sequence of two supercritical Andronov – Hopf bifurcations and a subcritical Neymark – Saker bifurcation. Therefore, the multistability emerges as a result of gaining stability by the unstable limit set that existed before the multistability appears. Conclusion: The discovered mechanism of multistability formation opens up wide possibilities for managing the multistability, which are inaccessible for systems in which the multistability is realized through tangential bifurcations. In contrast to the tangential bifurcation, the subcritical Neymark – Sacker bifurcation assumes the existence of a limit cycle both before and after the bifurcation. Thus, it is possible to use a wide range of methods and tools to stabilize saddle limit cycles in order to control the boundaries of the multistability region in the space of control parameters of the system.

Robust, coherent, and synchronized circadian clock-controlled oscillations along Anabaena filaments

Circadian clocks display remarkable reliability despite significant stochasticity in biomolecular reactions. We study the dynamics of a circadian clock-controlled gene at the individual cell level in Anabaena sp. PCC 7120, a multicellular filamentous cyanobacterium. We found significant synchronization and spatial coherence along filaments, clock coupling due to cell-cell communication, and gating of the cell cycle. Furthermore, we observed low-amplitude circadian oscillatory transcription of kai genes encoding the post-transcriptional core oscillatory circuit and high-amplitude oscillations of rpaA coding for the master regulator transducing the core clock output. Transcriptional oscillations of rpaA suggest an additional level of regulation. A stochastic one-dimensional toy model of coupled clock cores and their phosphorylation states shows that demographic noise can seed stochastic oscillations outside the region where deterministic limit cycles with circadian periods occur. The model reproduces the observed spatio-temporal coherence along filaments and provides a robust description of coupled circadian clocks in a multicellular organism.