Output Impulse Research Articles

Measurement of Transient Flash Evaporation Flow in Liquefied Gas Propulsion Using Dual-Plane ECT

In this paper, the transient flash evaporation flow in liquified gas propulsion (LGP) was measured using a dual-plane electrical capacitance tomography (ECT) sensor. The novelty mainly stems from a selection method for more accurate liquid holdup measurement, a constrained adaptive cross-correlation algorithm for more stable velocity, and compensation methods against the changes of temperature and pressure. By the selection method, inter-electrodes capacitances that contribute less to the flow measurement, are removed from each data frame and more accurate liquid holdup is derived via image reconstruction. The adaptive cross-correlation algorithm with a constraint on the correlation coefficient is adopted to alleviate the adverse effect of the fast changes of flow pattern on the velocity measurement. Then, the compensation methods are realized by correcting the deviations of phase density and permittivity caused by dramatic temperature and pressures changes. Simulations and experiments validated the effectiveness of the proposed methods to derive the mass flow rate of the two-phase flow via the measured liquid holdup, flow velocity and estimated phase density. It is shown that the remaining mass of propellant in the storage tank calculated from the mass flow rate is in good agreement with the measured reference by the electronic balance, where the average relative errors under different initial pressures are less than 10%. As the best of our knowledge, this is the first-time of transient flash evaporation flow measurement in a lab-built LGP device, which is promising to be applied for the effective online control to maximize the output impulse of LGP and estimate the remaining life of small spacecrafts.

Design of 4-stage Marx generator using gas discharge tube

In this paper, a Marx generator voltage multiplier as an impulse generator made of multi-stage resistors and capacitors to generate a high voltage is proposed. In order to generate a high voltage pulse, a number of capacitors are connected in parallel to charge up during on time and then in series to generate higher voltage during off period. In this research, a 6kV Marx generator voltage multiplier is designed using gas discharge tube (GDT) as an electronic switch to breakdown voltage. The Marx generator circuit is designed to charge the storage capacitor for high impulse voltage and current generator applications. According to IEC 61000-4-5 class 4 standards, the storage capacitor must be charged up to 4 kV. The results show that the proposed Marx generator can produce voltages up to 6.8 kV. However, the storage capacitor could be charged up to 1 kV, instead of 4 kV in the standard. That is because the output impulse voltage has narrow time period.

THE STUDY OF THE ELECTROPHYSICAL PROPERTIES OF A COMPOSITE MEMRISTOR-DIODE CROSSBAR AS A BASIS OF THE NEUROPROCESSOR HARDWARE IMPLEMENTATION

The aim of this article lies in checking the efficiency of memory and logic matrices. Achieving this has required producing a composite memristor-diode crossbar and studying its electrophysical properties. For these purposes, the authors have made a measuring bench, which consists of a composite memristor-diode crossbar, control peripheral circuitry, based on discrete elements with CMOS logic, and Keithley SourceMeter 2400. The silicon junction p-Si/n-Si has been chosen because its electrical properties better suit the Zenner diode’s requirements compared to the p-Si/ZnO junction. The memristor-diode crossbar with the TiN/Ti0,93Al0,07Ox/p-Si/n-Si/W structure was made with implementation of a new diode. The results show that the crossbar cell with a p-Si/n-Si diode has better rectifying properties in comparison with a p-Si/ZnOx diode, because the current in the crossbar cell with positive voltage bias is much higher than with negative voltage bias. Strong rectifying properties of the cell are necessary for the functioning of diode logic in the logic matrix and for memristor state recording in the logic and memory matrices. The study of electrophysical properties of the composite memristor-diode crossbar, measurement of current-voltage characteristics of the diode and composite memristor-diode crossbar cell and signal processing were performed. The signal processing was performed in the following modes: addition of output impulses of neurons and their routing to synapses of other neurons; multiplication of number matrix by vector, performed in the memory matrix with weighing and totalling of signals; and associative self-learning. For the first time, the generation of a new association (new knowledge) in the composite memristor-diode crossbar has been shown, as opposed to associative self-learning in existing hardware neural networks with discrete-memristors-based synapses. The change of crossbar cell’s output current caused by parasitic currents through adjacent cells has been determined. The results show that the control over Zenner diode characteristics allows reducing the power consumption of the composite crossbar. Obtained electrophysical characteristics prove the efficiency of the composite memristor-diode crossbar, intended for production of the memory and logic matrices.

Influencing factors of the performance of an impact buffering made of the composite granular chain

The influencing factors of the performances of an impact buffering made of the composite granular chain of spheres were investigated by both the finite element analysis and experiments. The composite granular chain was prepared by inserting an adjustable chain into a one-dimensional steel granular chain of spheres. It is suggested to select the key influencing factor as λ=(EvEs)23ρvρs, which determined the features of output impulses. The amplitude ratios of primary and secondary output impulses to the incident impulse of highly nonlinear solitary wave (HNSW) and the time delay between the primary and secondary output impulses demonstrated the two-stage dependencies on the parameter of λ. The two stages were separated from each other by the case of λ = =1. It was suggested to construct an impact buffering with near-zero λ in order to minimize the amplitude of primary output impulse. The amplitude attenuation of the primary output impulse in the adjustable chain followed the power law and the power exponent was negatively correlated with the value of λ. As for a composite chain with a given parameter of λ, through increasing the length of the adjustable chain, the amplitude of the primary output impulse could be decreased in order to improve the performance of impact buffering.

First Passage Time Distribution for Spiking Neuron with Delayed Excitatory Feedback

A class of spiking neuronal models with threshold 2 is considered. It is defined by a set of conditions typical for basic threshold-type models, such as the leaky integrate-and-fire (LIF) or the binding neuron model, and also for some artificial neurons. A neuron is stimulated with a Poisson stream of excitatory impulses. Each output impulse is conveyed through the feedback line to the neuron input after finite delay [Formula: see text]. This impulse is identical to those delivered from the input stream. We have obtained a general relation allowing calculating exactly the probability density function (PDF) [Formula: see text] for distribution of the first passage time of crossing the threshold, which is the distribution of output interspike intervals (ISI) values for this neuron. The calculation is based on known PDF [Formula: see text] for that same neuron without feedback, intensity of the input stream [Formula: see text] and properties of the feedback line. Also, we derive exact relation for calculating the moments of [Formula: see text] based on known moments of [Formula: see text].The obtained general expression for [Formula: see text] is checked numerically using Monte Carlo simulation for the case of LIF model. The course of [Formula: see text] has a [Formula: see text]-function-type peculiarity. This fact contributes to the discussion about the possibility to model neuronal activity with Poisson process, supporting the “no” answer.

Digital contour of linear control in the pulse voltage stabilizer

This paper provides an analysis of the operation of the pulse voltage stabilizer with a digital control contour, which uses a linear dependence between power switch opening pulse duration and the output voltage deviation from the nominal one. The influence of the errors, caused by digital data representation, on the control loop output impulse duration was evaluated. The conditions that minimize the influence of these errors on the stabilizer operation are revealed.

Crossing Total Occlusions using a hydraulic pressure wave: a feasibility study

Crossing highly calcified occlusions is technically challenging mainly due to guidewire buckling. In an effort to prevent buckling, a catheter that uses a dynamic impulse load is proposed. The proposed Wave catheter consists of an input plunger to generate an impulse at the handle, a hydraulic pressure wave confined within a ∅2 mm catheter to transfer the impulse towards the tip, and an output plunger to transfer the impulse to the occlusion. To determine the feasibility of this catheter, an experiment was performed in which the input and output impulses were recorded as a function of the catheter type, curvature, and plunger travel distance. Additionally, the system was tested on artificial CTO models to determine the clinical validity. The catheter has illustrated the ability to safely transfer high-force impulses of up to 43 N (1.5 N required) with only minimum catheter type and no curvature dependency, allowing for delivering high-force impulses through tortuous vasculature and under any angle. Furthermore, the catheter was able to penetrate the artificial CTO models within 1 strike.

Relation Between Firing Statistics of Spiking Neuron with Delayed Fast Inhibitory Feedback and Without Feedback

We consider a class of spiking neuronal models, defined by a set of conditions typical for basic threshold-type models, such as the leaky integrate-and-fire or the binding neuron model and also for some artificial neurons. A neuron is fed with a Poisson process. Each output impulse is applied to the neuron itself after a finite delay [Formula: see text]. This impulse acts as being delivered through a fast Cl-type inhibitory synapse. We derive a general relation which allows calculating exactly the probability density function (pdf) [Formula: see text] of output interspike intervals of a neuron with feedback based on known pdf [Formula: see text] for the same neuron without feedback and on the properties of the feedback line (the [Formula: see text] value). Similar relations between corresponding moments are derived.Furthermore, we prove that the initial segment of pdf [Formula: see text] for a neuron with a fixed threshold level is the same for any neuron satisfying the imposed conditions and is completely determined by the input stream. For the Poisson input stream, we calculate that initial segment exactly and, based on it, obtain exactly the initial segment of pdf [Formula: see text] for a neuron with feedback. That is the initial segment of [Formula: see text] is model-independent as well. The obtained expressions are checked by means of Monte Carlo simulation. The course of [Formula: see text] has a pronounced peculiarity, which makes it impossible to approximate [Formula: see text] by Poisson or another simple stochastic process.

An Electric Stimulator for Intraoperative Verification and Monitoring of the State of the Facial Nerve and the Muscles of Expression

An electric stimulator for pre-operative electrical diagnosis and intraoperative verification of nerves and muscles in the maxillofacial area is described. A block diagram of the apparatus is presented and the parameters of the output impulses and stimulation programs used at the pre-operative and intraoperative stages are described. Use of the instrument in neurosurgical operations increases the effectiveness of assessments of the physiological state of nerves and decreases the risk of traumatization. Results were obtained without using neuromonitoring instrumentation based on recording electrical activity in nerves and muscles.

THE ESTABLISHMENT AND IMPLEMENTATION OF SUSTAINABLE DEVELOPMENT POLICY IN THE CANDIDATE COUNTRIES FOR EU MEMBERSHIP

In the article the formation and implementation of sustainable development policy in the candidate countries for EU membership are examined and trends that must be taken into consideration in the process of European integration of Ukraine are singled out. It is important for Ukraine to consider the experience of Turkey in joining the EU. In assessing the prospects of European integration of Ukraine and Turkey, it may be noted that the EU's relations with the applicant country can be compared to a dynamic system that is balanced with the account of the output impulses on both sides. That is, the European integration of these countries is a product of interaction of these processes within the EU as well as within these countries. Of course, the EU, on the one hand, and Ukraine and Turkey - on the other, assess the possible effects of integration in the light of the analysis of costs and effectiveness, and this is not always clearly considered by both parties as a "win-win" outcome. It is also important to study the experience of Central and East European countries to meet the requirements of environmental legislation of the EU in the period of preparation for the EU accession. Hence, it is necessary to analyze the adjustment of Central and East European countries to the EU requirements in "Environment" sphere, identify sources of financing of adaptation programs in the field of environmental protection, describe the main lines of the strategy of implementation of the EU environmental law requirements in CEE countries. Key words: candidate countries, sustainable development, ecological and economic development, integration.

Carrier-Based Cmos Impulse Generator for Ultrawideband Vehicular Radar Application

This article presents a CMOS ultrawideband (UWB) impulse generator using a 0.13-μm CMOS technology for the application of UWB 22–29-GHz vehicular radar. The proposed impulse generator has a pulse-modulated carrier-based architecture. The proposed design is power efficient and spectrum controllable with a frequency tuning range of 800 MHz. The output impulse has a pulse width less than 0.55 ns providing a high range resolution for the UWB vehicular radar systems. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1881–1887, 2013 10.1002/mop.27715

The Optimization Study about Technological Parameters of YAG Laser Precision Cutting Stainless Sheet

Using high power Nd3+:YAG pulse laser for precision cutting stainless sheet, study the effects of the laser cutting technological parameters on quality of cutting surface and joint-cutting width. The data of single factor experiment proved： With the increasing of scanning velocity, the joint-cutting width decreased; the width increased with the increasing of scanning velocity, laser current, impulse frequency and impulse width; the increasing of impulse frequency may improve the processing quality and ultimate cutting speed; the data of two-factors experiment proved: when the output power and impulse width are fixed, the impulse frequency will be increased, the joint-cutting width will be decreased; when the output power and impulse frequency are fixed, the impulse width will be increased, the joint-cutting width will be decreased.

Case report: Vagal nerve stimulation and late onset asystole

Rohit Shankar , Victor Oluwaseyi Olotu *, Nicholas Cole , Heather Sullivan , Caryn Jory c Neuropsychiatry, Epilepsy and Memory Service, Cornwall Partnership NHS Foundation Trust, Chy Govenek, Threemilestone Industrial Estate, Threemilestone, Truro, Cornwall TR4 9LD, United Kingdom Care of the Elderly Department, Royal Cornwall Hospital NHS Trust, Treliske, Truro, Cornwall TR1 3LJ, United Kingdom c East Cornwall Resource Centre, Cornwall Partnership NHS Foundation Trust, Unit 10, Bodmin Business Centre, Harleigh Road, Bodmin, Cornwall PL31 1AH, United Kingdom

A rapid 2-MV impulse generator

A high-voltage nanosecond impulse generator was developed and tested in order to create electromagnetic impulses (EMIs) in a given area. Tests revealed the characteristics of the generator’s output impulse: the rise (at a level 0.1–0.9) is about 3.2 ns, the length is 27 ns at half-deflation, and the magnitude is 2 MV. The generator is used to test large-size equipment for tolerance to industrial EMIs.

Application of step‐response test for evaluation of uncertainty of standard measuring system for lightning‐impulse high voltage

AbstractIn evaluating the uncertainty of the standard measuring system for lightning‐impulse high voltages, which is composed of a standard voltage divider, a digital recorder, and calibrators, step‐response tests of the standard voltage divider may be useful. In this paper, a convolution algorithm is employed to calculate the output impulse voltage waveforms from measured step‐response waveforms. The uncertainties of peak‐value measurement due to the influence of the nominal epoch, uncertainty of the peak‐value measurement due to dispersion of the AC scale factor, and uncertainty of the virtual front‐time measurement due to long‐term stability are evaluated. Furthermore, the error of the virtual front time of the output waveforms is discussed. The front part of the step‐response waveform, t≤ T30%, does not influence the error of the virtual front time. Therefore, for the standard voltage divider, the step‐response parameters, that is, the experimental response time, partial response time, settling time, and overshoot, have almost nothing to do with the error of the virtual front time. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(2): 24–32, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21279

Spiking Statistics of Excitatory Neuron with Feedback

Firing statistics of excitatory binding neuron (BN) is considered. The neuron is driven externally by a Poisson stream. Influence of feedback, which conveys every output impulse to the input with time delay , on the statistics of output spikes is studied. The resulting output stream is not Poissonian, and the authors obtain its inter-spike intervals (ISI) distribution for the case of BN, BN with instantaneous, , and delayed, , feedback. Output statistics of neuron with delayed feedback differs essentially from that found for the case of no feedback as well as from the case of instantaneous feedback. ISI distributions, found for delayed feedback, are characterized with jumps, derivative discontinuities and include -function type singularity. Also, for non-zero refractory time, the authors obtain multiple-ISI conditional probability density and prove, that delayed feedback presence results in non-Markovian statistics of neuronal firing. It is concluded, that delayed feedback presence can radically change neuronal firing statistics.

Features of Active Electrical States of Asymmetrical Dendrites of Brainstem Motoneurons during Generation of Stochastic Implulse Patterns: a Simulation Study

On models of motoneurons of the n. abducens nucleus with reconstructed dendritic arborizations having an active membrane, we investigated features of the relationships between passive transfer properties and dynamics of excitation states of asymmetrical dendrites during generation of complex periodical and stochastic impulse patterns (output neuronal codes). Various patterns were obtained by varying the intensity of tonic synaptic excitation homogeneously distributed over the dendrites. The electrical states of sites belonging to branches of the same dendrite or different dendrites were compared. For this comparison, branches were selected, which, according to the earlier performed cluster analysis, were assigned to the groups (electrotonic clusters) with a high and a low effectiveness of passive transfer of the somatopetal current. The selection took into account features of the dendritic structure of neurons of the exemined type. These were: (i) the presence of groups of the asymmetrical branches differing from each other according to their belonging to different clusters (high or low transfer effectiveness) in different dendrites, and (ii) the presence of branches belonging to different dendrites characterized by significantly different orientations in three-dimensional space of the brainstem within each electrical cluster. Comparative analysis showed that, in a given dendrite during generation of a complex periodical pattern, the asymmetrical branches belonging to high- or low-efficiency clusters were characterized by being in different states (high or low depolarization) in different phases of generation of repeated sequences of action potentials (APs). This relationship was consistent with those previously detected in neurons of other types and in other specimens of neurons of the above-mentioned type. During generation of such periodical spike patterns, the branches of different dendrites belonging to the same electrotonic cluster were in similar states. Similar relationships between the states of the branches of the same dendrite belonging to different clusters were also observed during generation of complex stochastic (non-periodical) impulse patterns. In the latter case, however, the essential feature was that the branches of different dendrites belonging to the same electrotonic cluster were often in opposite states. Thus, the number of combinations of discrete electrical states of asymmetrical parts of the dendritic arborization was much greater. Probably, it is precisely this circumstance that determined the quasi-stochastic nature of the output impulse pattern.

Dependence of Transformation of Intrinsic Rhythmic Impulse Activity of Neurons on Spatio-Temporal Organization of Synaptic Actions on Dendrites: A Simulation Study

The aim of the study to elucidate the biophysical mechanisms able to determine specific transformations of the patterns of output signals of neurons (neuronal impulse codes) depending on the spatio-temporal organization of synaptic actions coming to the dendrites. We studied mathematical models of the neocortical layer 5 pyramidal neurons built according to the results of computer reconstruction of their dendritic arborizations and experimental data on the voltage-dependent conductivities of their dendritic membrane. This work is a continuation of our previous studies that showed the existence of certain relations between the complexity of neural impulse codes, on the one hand, and the complexity, size, metrical asymmetry of branching, and nonlinear membrane properties of the dendrites, on the other hand. This relation determines synchronous (with some phase shifts) or asynchronous transitions of asymmetrical dendritic subtrees between high and low depolarization states during the generation of output impulse patterns in response to distributed tonic activation of dendritic inputs. In this work we demonstrate the first time that the appearance and pattern of transformations of complex periodical impulse trains at the neuron’s output associated with receiving a short series of presynaptic action potentials are determined not only by the time of arrival of such a series, but also by their spatial addressing to asymmetric dendritic subtrees; the latter, in this case, may be in the same (synchronous transitions) or different (asynchronous transitions) electrical states. Biophysically, this phenomenon is based on a significant excess of the driving potential for a synaptic excitatory current in low-depolarization regions, as compared with that in high-depolarization dendritic regions receiving phasic synaptic stimuli. These findings open a novel aspect of the functioning of neurons and neuronal networks.

Study of a Magnetic Switch for the SG-III Energy Module

The SG-III energy module, which supplies pumping energy for Xenon (Xe) flashlamps, is one of the most important modules in large laser facilities. A two-electrode spark gap switch is used as the main discharge switch and is triggered by a Marx generator. The peak value of the output impulse generated by the Marx generator is about 180 kV, and its rise time is about 10 ns. In order to prevent the key elements (e.g., Xe flashlamps) from being damaged by the trigger impulse, a magnetic switch is used to isolate the high-voltage impulse. The design, working principle and performance of a magnetic switch based on Fe-based nanocrystals are presented in this paper. Compared with the magnetic switch employed in magnetic pulse compressors (MPCs), the magnetic switch in SGIII works under a single nanosecond impulse. It corresponds to the initial magnetization curve of the B-H curve. The parameters of the Fe-based nanocrystals are obtained by experiments. The unsaturated inductance, saturated inductance and saturation time are the key parameters of the magnetic switch in SG-III and are considered in the design. Finally, the experimental results for the magnetic switch in SG-III are presented.

Design and Construction of a Trigger Generator Based on Pulse Transformer for Spark Gap Switch

A two-electrode graphite spark gap switch is used as the main discharge switch and triggered by a reliable trigger generator in a pulsed-power conditioning system. The trigger generator based on resonant charging of a pulse transformer is constructed. An appropriate ratio can be obtained when using resonant charging based on a core-type pulse transformer. The charging time is dependent on the leakage inductance and the capacitance of the primary and secondary capacitors. The stray resistance and magnetizing inductance of the resonant charging circuit have an impact on ratio and energy transmission efficiency. A dry-type pulse transformer with a load of 1.08 nF, an output voltage of more than 130 kV, and a winding ratio of 65 is presented. A self-breakdown three-electrode output switch is used to shorten the rise time of the output impulse. The deviation of the self-breakdown voltage of the self-breakdown three-electrode output switch is much smaller than that of the self-breakdown two-electrode output switch. It assures that the trigger generator has a low jitter of output impulse when a lot of energy modules work simultaneously. The output impulse of the trigger generator with a peak value of more than 120 kV and a rise time of less than 30 ns can trigger the two-electrode graphite spark gap switch reliably.