Sequence Of Rectangular Pulses Research Articles

Micro-Electro-Mechanical Systems in Light Stabilization.

This article discusses application considerations in the micro-electro-mechanical system's optical sensor. Furthermore, the provided analysis is limited to application issues occurring in research or industrial applications. In particular, a case was discussed where the sensor was used as a feedback signal source. Its output signal is used to stabilize the flux of an LED lamp. Thus, the function of the sensor was the periodic measurement of the spectral flux distribution. The application problem of such a sensor is the output analogue signal conditioning. This is necessary to perform analogue-to-digital conversion and further digital processing. In the discussed case, design limitations come from the specifics of the output signal. This signal is a sequence of rectangular pulses, which can have different frequencies, and their amplitude varies over a wide range. The fact such a signal must be conditioned additionally discourages some optical researchers from using such sensors. The developed driver allows measurement using an optical light sensor in the band from 340 nm to 780 nm with a resolution of about 12 nm; in the range of flux values from about 10 nW to 1 μW, and frequencies up to several kHz. The proposed sensor driver was developed and tested. Measurement results are presented in the paper's final part.

Действие прямоугольных электрических импульсов низкой частоты на трихоплакса (тип Placozoa)

Влияние низкочастотного электромагнитного излучения (НЭМИ) на растения и животных, включая человека, достаточно спорно. Мало известно и о воздействии НЭМИ на гидробионтов. Мы изучили действие прямоугольных импульсов напряжения различной амплитуды, длительности и скважности, пропущенных через морскую воду, на трихоплакса (тип Placozoa) как на возможную тестовую лабораторную модель. В опытах использовали три штамма Placozoa, Trichoplax adhaerens (H1), Trichoplax sp. (H2) и Hoilungia hongkongensis (H13), отобранных на стационарной стадии роста культуры. Для генерации последовательности прямоугольных импульсов заданной длительности и скважности с частотой до 2 кГц применяли аппаратную платформу Arduino Uno. Среднее значение напряжения до 500 мВ регулировали с помощью схемы делителя напряжения. Для доказательства специфичности действия электрических импульсов на потенциалзависимые кальциевые каналы трихоплакса использовали ингибитор активности кальциевых каналов амлодипин. Животных стимулировали электрическим током под стереомикроскопом. Электроды располагали в непосредственной близости от животного. Исследовали сопутствующие изменения поведения и морфологии пластинки трихоплакса. Выделяли стимулирующие и подавляющие воздействия. Наблюдения документировали с помощью фото- и видеосъёмки. Отслеживали траектории движения отдельных особей. Увеличение напряжения на электродах при фиксированной частоте 20 Гц приводило к тому, что животные штамма H2 покидали «зону электродов» в течение нескольких минут при 25 мВ, однако теряли подвижность пропорционально росту напряжения и обездвиживались при 500 мВ. Именно поэтому в дальнейших опытах применяли напряжение 50 мВ. В экспериментах с двумя электродами, находящимися с одной стороны трихоплакса, у животного было больше возможностей перемещаться в разных направлениях, чем в случае расположения электродов по обеим сторонам пластинки. Направление движения использовали как характеристический признак. Отмечено, что трихоплаксы мигрируют в области с низкой плотностью линий электрического поля, которые расположены вдали или за электродами. Животные из старой культуры отличались меньшей чувствительностью к электрическому раздражителю. Штамм H2 был наиболее чувствительным и демонстрировал более выраженные физиологические реакции на частотах 2 Гц и 2 кГц с напряжением 50 мВ, чем штамм H1 и особенно штамм H13. В зависимости от длительности стимулирующих прямоугольных импульсов, их числа, амплитуды и варьирующей частоты менялись двигательные реакции и морфология животных: от направленной или стохастической миграции в сторону анода/катода или от него до обездвиживания животных, увеличения оптической плотности по периферии и в центре пластинки и до сворачивания трихоплакса и отделения его от субстрата. В дополнительных опытах на Trichoplax sp. H2 показано, что при длительности импульсов 35 мс и задержке импульсов от 1 мс до 10 с доля обездвиженных животных увеличивается до 80 % при минимальной задержке. Тем не менее в случае применения амлодипина в концентрации 25 нМ практически все трихоплаксы в течение нескольких минут сохраняли подвижность несмотря на обработку электрическими импульсами. Между тем при использовании амлодипина в концентрации 250 нМ животные двигались дискоординированно и не могли покинуть «электродную ловушку». Далее пластинка трихоплакса становилась ригидной, что выражалось в неизменности формы животного при движении. Наконец, амлодипин в концентрации 50 мкМ вызывал быстрое сворачивание краёв трихоплакса в розетку в вентрально-дорсальном направлении и последующую диссоциацию пластинки на отдельные клетки. В целом применяемое электрическое воздействие имело кумулятивный, но обратимый эффект, который, как предполагается, может быть связан с работой потенциалзависимых кальциевых каналов. Амлодипин в большой концентрации (50 мкМ) вызывал разрушение трихоплакса, в умеренной (250 нМ) он нарушал, вероятно, распространение волн активации, что приводило к дискоординации движений животного, а в малой (25 нМ) предотвращал электрошок.

Analysis of memristor-based differentiating circuit

PurposeThe purpose of this paper is to propose a detailed analysis of a memristor-based differentiating circuit with buffering amplifier, a capacitor and a memristor.Design/methodology/approachThe analyzed circuit is based on a resistor–capacitor differentiating scheme together with a buffering operational amplifier. In the proposed circuit, the resistor is replaced by a memristor element.FindingsThe considered circuit and its classical analog are investigated using a rectangular pulse sequence as input signal. A comparison between the derived results is made. An advantage of the proposed memristor circuit is the shortened duration, i.e. higher localization, of the output pulses of rectangular input pulses to be derived.Originality/valueDifferentiating circuits are important modules in radio-electronics. Because of their widespread usage, it is of higher interest that their new potential schematic realizations are analyzed. For the computer simulations, a previously proposed modified nonlinear memristor model is used. Several of the best and widely used basic memristor models are applied as well.

Optimal time-domain pulse width modulation for three-phase inverters

An optimal time-domain technique for pulse-width modulation (PWM) in three-phase inverters is presented. This technique is based on the time-domain per phase analysis of three-phase inverters for linear, balanced output load circuits. Exact analytical solutions for the output phase currents are presented for first, second, and third order circuits for any sequence of rectangular pulses. Next, the role of symmetries in the structure of three-phase PWM inverter voltages is discussed. Finally, using the exact analytical solutions for phase-currents as well as symmetry considerations, minimization of output current harmonics is set up as an optimization problem. Sample numerical results are presented that highlight improvements in the performance of three-phase inverters.

ANALYTICAL SYNTHESIS OF FORCED PULSE ELECTRONIC DRIVE CONTROL OF A TRACKING SYSTEM

The problem of analytical synthesis of a control signal by a linear dynamical system is considered. As an optimization criterion, it is proposed to consider the transition time of the system from the initial state to a given final state. This type of control is called forced, providing the maximum system speed. The principle of solving this problem is considered on the basis of application of uncertain Lagrange multipliers and the Pontryagin maximum principle. Expressions are obtained for the matrix of transitions of the system and the control signal in a vector form.As an example, the electric drive described by the widespread second-order mathematical model is considered to evaluate the efficiency of the proposed method. Qualitative illustrations of the operability of the proposed approach, obtained by modeling in the Mathcad environment, and quantitative characteristics of the change in the input and output signals of the hypothetical control system are presented. It is shown that the use of forced control does not lead to the output of variables characterizing the state of the system, beyond the limits of admissible values.The use of forced control makes it possible to synthesize the control law in the form of a sequence of rectangular pulses of constant amplitude determined by the power source, variable duty cycle and polarity. This approach can be used for the control of DC-type DC motors used in various tracking systems used on unmanned aerial vehicles. Key words: forced control, target function, electric drive, pulse train. The use of forced control makes it possible to synthesize the control law in the form of a sequence of rectangular pulses of constant amplitude determined by the power source, variable duty cycle and polarity. This approach can be used for the control of DC-type DC motors used in various tracking systems used on unmanned aerial vehicles.

Frequency‐domain analysis for pulse current sources in transient electromagnetic method

ABSTRACTThe transient electromagnetic method has a wide range of depth of exploration in the ground. The transient‐electromagnetic‐method‐based shallow sounding is becoming popular in engineering geophysics such as grounding grid measurement, pipeline detection, and mine exploration. It is useful for shallow sounding to raise the transmitting frequency, improve the spectral resolution, and enhance the power of withstanding all kinds of near‐surface noise. Therefore, a well‐designed transmitter current waveform should not only induce more effective geoelectric information at a low energy cost but also prevent external interferences during transient electromagnetic method prospecting.For this purpose, the frequency‐domain characteristics of single‐pulse waveforms and multi‐pulse sequences are analysed, on the basis of three fundamental waveforms—rectangular, triangular, and half‐sine shapes. The energy efficiency ratio, high‐frequency energy percentage, and frequency resolution are introduced to evaluate the performance of the transmitter current source, in a numerical or graphical manner. Furthermore, six window functions are used to modulate the rectangular pulse sequence. The analysis and simulation results prove that the pulse current source modulated by the Blackman window is advantageous in terms of energy efficiency, high‐frequency content, and frequency resolution. In addition, the Blackman modulating sequence has many blank frequency bands (also called identifiable bands) where the noise is completely exposed and easy to remove. This work is useful for the design, optimisation, and selection of transmitter current waveforms for different applications, especially for near‐surface geophysical prospecting.

Test signals choice for system characteristics identification: Taking into account the output deviation range constraint

This paper considers active identification methods for the temporal characteristics of an object in a closed-loop control system. A comparative analysis of binary signals, namely, pseudorandom and regular sequences of rectangular pulses, is performed under a constraint imposed on the output deviation range of the controlled parameter. Using calculations, it is shown that the best signal choice depends on several factors and, first of all, on the noise level; under a sufficiently small noise level, the regular binary sequence of rectangular pulses seems preferable.

Разложение функции, описывающей последовательность прямоугольных импульсов, в тригонометрический ряд Фурье

Разложение функции, описывающей последовательность прямоугольных импульсов, в тригонометрический ряд Фурье

Nonperturbative dynamical decoupling with random control.

Parametric fluctuations or stochastic signals are introduced into the rectangular pulse sequence to investigate the feasibility of random dynamical decoupling. In a large parameter region, we find that the out-of-order control pulses work as well as the regular pulses for dynamical decoupling and dissipation suppression. Calculations and analysis are enabled by and based on a nonperturbative dynamical decoupling approach allowed by an exact quantum-state-diffusion equation. When the average frequency and duration of the pulse sequence take proper values, the random control sequence is robust, fault-tolerant, and insensitive to pulse strength deviations and interpulse temporal separation in the quasi-periodic sequence. This relaxes the operational requirements placed on quantum control devices to a great deal.

Method for Active Radar Seeker to Suppress Convolution Modulation Smart Jamming

Smart jamming based on convolution modulation brings a great threat to active radar seeker. In order to counter the jamming, a method of orthogonal projection is designed. Firstly, both the mathematic models of linear frequency modulation (LFM) signal and convolution modulation smart jamming are made. Secondly, the anti-interference principle of orthogonal projection is analyzed, on the basis of which a reasonable filter is designed. Thirdly, simulations of signals respectively convolved with noise, triangle pulse sequence and rectangular pulse sequence are made, which verifies its good interference effects. The conclusion is that the method can effectively suppress the convolution modulation smart jamming.

Numerical methods for determining the response in a dynamic mode

The transient processes lead to the fact that the calculations should be done in a dynamic state of the circuit. Therefore, the low-pass filter, functioning as integrator and used in most radio devices up to power supply units, should be analyzed in real time, i.e. in a dynamic mode. The method of transmission dynamic coefficient is of some interest, it differs from the stationary coefficient because it involves not only the instantaneous frequency value, but also the values of phase derivatives with respect to time. When determining the dynamic system output signal it is necessary to use z-conversion, allowing to eliminate the calculation errors which occur due to the limited frequency properties. Taking into account that the circuit remains in a dynamic mode for a long time, the calculation of passage of the limited sequence of rectangular pulses was carried out, spectral density at the circuit output was determined, z-image of the input signal and transmission coefficient were received, the signal at the circuit output was figured out. Using the z-conversion allows improving the accuracy of calculations and further determination of dynamic features of integrator. It can be concluded that, indeed, the circuit remains in dynamic mode for a long time. Each subsequent pulse at the circuit input causes the next stage, i.e. gradual voltage increase at the output

Poisson Probability Density Identification a sequence of rectangular pulses with Gaussian amplitude distribution

Possibility of application a unimodal twocomponent Gaussian mixture of distributions for finding probability densities of rectangular Poisson pulse processes with normally distributed amplitudes are determined. Calculation formulas that allow to identificate the mixture’s parameters are obtained. Dependence of the error in Gaussian approximation to the probability densities of Poisson pulse processes on the pulse duration and intensity is analyzed.

EXPERIMENTAL DYNAMICAL EVOLUTION OF THE BRILLOUIN PRECURSOR FOR BROADBAND WIRELESS COMMUNICATION THROUGH VEGETATION

In this paper, we report experimental results on detecting and analyzing the Brillouin precursor through vegetation at frequencies from 500MHz to 3GHz. An experimental method to collect data is reported. The outcomes in terms of energy and time-spreading are presented using modulated rectangular and Gaussian pulses, as well as a sequence of rectangular pulses. Using fleld-collected data, this study shows the estimated dynamical evolution of the Brillouin precursor flelds for wideband wireless systems, such as those represented by IEEE 802.16. The advantages of Brillouin precursors in terms of power spectrum density and bit energy are discussed. Complex relative permittivity is extracted from the experimental data and is used in theoretical formulation to analyze dispersive propagation for any kind of input waveform. Finally, a near-optimal pulse is proposed to achieve maximum propagation distance and/or signal-to-noise ratio for the transmission of bit stream sequences through vegetation.

Time dynamics of the nematic liquid crystal director in the field of a sequence of rectangular pulses

We study theoretically and experimentally the Freedericksz transition in a sequence of rectangular pulses. We show the dependence of the accumulation effect on the pulse filling coefficient. We demonstrate that at a constant energy value in a pulse, the accumulation phenomenon substantially depends on the pulse repetition frequency. An analytical consideration of the initial stage of development of orientational instability fully confirms the conclusions of numerical analysis. The results of experiment agree well with the conclusions of theoretical analysis.

Digital data transmission between neuronlike elements

The problem of digital data transmission between two neuronlike systems has been investigated. The former of a sequence of rectangular pulses is used as an information signal source. The behavior of neuronlike elements is described with the help of the Hodgkin-Huxley mathematical model. Such a system is shown to form the communications channel of fairly high quality in terms of the classical theory of information transmission.

Two-copula based simulation for detention basin design

This article presents a Monte Carlo simulation model based on Clayton copula to generate synthetic sequences of rainfall storms whose likelihood of occurrence is in consonance with historical records. These sequences are used as rainfall input data for the Storm Water Management Model to analyse a 3 km2 watershed in the city of Granada, Spain. The objective of our study is to estimate the optimal volume of a detention basin that would solve the problem created by a downstream combined sewer system (CSS), part of which is undersized and which cannot be enlarged without considerable cost. In this model, the synthetic rainfall sequences provide multiple inputs to the CSS model, which produce a range of model outputs. Risk-based analysis of these outputs helps to quantify the variability of the CSS response. As a result, our model enables decisions based on the comparison of expected outcomes and the costs of different choices. The rainfall storms are represented as a sequence of rectangular pulses, whose occurrences are driven by a Poisson process with a given arrival rate. Both storm durations and average storm intensities are fitted as Pareto distributions and the dependence between these variables is described using Clayton copula.

Theoretical investigation of modulated currents in open nanostructures

We investigate theoretically the transport properties of a mesoscopic system driven by a sequence of rectangular pulses applied at the contact to the input (left) lead. The characteristics of the current which would be measured in the output (right) lead are discussed in relation with the spectral properties of the sample. The time-dependent currents are calculated via a generalized non-Markovian master equation scheme. We study the transient response of a quantum dot and of a narrow quantum wire. We show that the output response depends not only on the lead-sample coupling and on the length of the pulse but also on the states that propagate the input signal. We find that by increasing the bias window the new states available for transport induce additional structure in the relaxation current due to different dynamical tunneling processes. The delay of the output signal with respect to the input current in the case of the narrow quantum wire is associated to the transient time through the wire.

Analysis of the Dynamic Characteristics of a Vacuum System

The gas pressure variation in a vacuum system featuring dynamic gas evolution in the form of a sequence of rectangular pulses has been experimentally studied. The observed behavior can be described in terms of a model developed previously.

Suppressing pulsed microwave signals in a nonlinear spin wave interferometer

The suppression of S-band microwave pulses in a nonlinear spin wave interferometer was experimentally studied for the first time. The microwave interferometer employed a nonlinear spin wave phase shifter based on an yttrium iron garnet film. A signal representing a periodic sequence of rectangular pulses with a power of up to 2.5 mW passes through the nonlinear interferometer without distortion, while an increase in the pulse power to 13.8 mW results in virtually complete suppression of the pulsed signal.

On analytical expressions for the distribution of the filtered output of square envelope receivers with signal and colored Gaussian noise input

Closed-form expressions for the moment generating function (MGF) of the filtered output of square envelope receivers with signal and colored Gaussian noise input are derived. The informative signal is a binary sequence of rectangular pulses. The considered Gaussian processes are the Wiener process, a Gaussian process with linear covariance (moving average), and the Ornstein-Uhlenbeck process. The derived MGFs are then applied to the problem of finding the quantum limit for optically preamplified, direct detection receivers.