scholarly journals Deterioration of Accuracy Characteristics of Solid-State Wave Gyroscopes when the Excitation Frequency Is Adjusted from the Resonance Frequency

2021 ◽  
Vol 19 (4) ◽  
pp. 4-17
Author(s):  
I.A. Vikhlyaev ◽  
K.V. Shishakov K.V.
Keyword(s):  
Solid State ◽  
Simulation Model ◽  
Direct Current ◽  
Excitation Frequency ◽  
Experimental Studies ◽  
Significant Loss ◽  
Ring Electrode ◽  
Measuring Device ◽  
State Wave ◽  
Frequency Correction

The paper presents the calculated and experimental study of the measure of deterioration of accuracy characteristics of solid wave gyroscopes when adjusting their frequency from the resonance one. To do this, a simulation model was built, which was researched in the Matlab package. The measurement device is modeled at the alternating and direct current. It is shown that the measure of mismatch of the calculation grid with the period of vibrations of the gyroscope resonator was the main reason for errors in calculating the angle of the gyroscope in the simulation model. This is confirmed by the graphs of dependencies of errors on the deviation of the excitation frequency from the resonance one. Experimental studies on laboratory models of non-industrial production confirmed the principle possibility of making a solid-state wave gyroscope design without the contour of phase auto-adjustment frequency, without a significant loss of the accuracy. To do this, three models of low-precision gyroscopes were created and researched. In the first layout, a variable-current measuring device was used, and the parametric swing of oscillations was performed by one ring electrode with an additional inclusion of a different-frequency correction path with sixteen electrodes. In the second layout, the previous diagram replaced the measuring device for working on a direct current. The third mock-up examined a two-channel eight-electrode control system. On all layouts it was permissible to work at the excitation frequency deviation from the resonant 5 kHz equal to the value (20 Hz). At the same time, the form of the systematic drift function has not changed much. And its amplitude and random error rate also changed acceptably.

scholarly journals Algorithms for Processing Measuring Signals in the Integrating Solid-State Wave Gyroscope

2021 ◽  
Vol 19 (4) ◽  
pp. 33-48
Author(s):  
K. V. Shishakov
Keyword(s):  
Solid State ◽  
Standing Wave ◽  
Direct Current ◽  
High Speed ◽  
Measuring Device ◽  
Assigned Value ◽  
State Wave ◽  
Angular Velocities ◽  
Sensor Signals ◽  
Modulated Signals

Different variants of algorithms for processing the internal signals of the measuring device of integrating solid-state wave gyroscopes are synthesized. The main attention is paid to the consideration of subtle factors affecting the accuracy of calculation of gyroscope output signals and measurement signals of internal circuits to ensure their effective operation. For this purpose, different models of capacitive sensor signals in the gyroscope measuring device and the measured structure of standing waves in its resonator are preliminarily considered. The traditional aggregation of sensor signals into measuring device signals is described. First, variants of algorithms for capacitive direct-current operating measuring devices are systematized and thoroughly analyzed. They are divided into algorithms with tuning for periodicity of resonant oscillations and without tuning for periodicity. Variants of calculations differing in accuracy are presented for: the angle of the operating standing wave, proportional to the measured rate of the gyroscope base rotation; the amplitude of the operating quadrature standing wave for the internal circuit of its assigned value maintenance; the amplitude of the quadrature standing wave for the internal circuit of its suppression; the frequency of the operating standing wave for tuning of the excitation system of resonator oscillations and for implementation of the digital quadrature coherent demodulator of the measuring device. It is shown that in the majority of practical applications algorithms with tuning to periodicity of resonant oscillations are more preferable from the point of view of the computational complexity. And computationally labor-intensive algorithms without periodicity tuning are intended for measuring increased angular velocities with the reduced time of "freezing" of measured parameters. Further the given algorithms for the direct-current measuring device are generalized on algorithms of processing of measuring signals when operating with the alternating current. The variants of computational algorithms reduction to the algorithms previously synthesized for the direct current are described. They mainly use demodulation of AC voltage signals, including digital processing of modulated signals using a high-speed analog-to-digital converter. In addition, algorithms for information extraction from AC measuring device signals with demodulation at the combined frequency of modulated signals are synthesized. The different variants of single-band demodulation of measurement signals and also algorithm of double-band demodulation of measuring device signals with the extended list of measured quantities are considered. The choice of the necessary algorithm depends on the requirements to the measured angular velocities, on the constructive implementation of the gyroscope measuring device and on the choice of technical characteristics of its components.

scholarly journals Solid-State DC Circuit Breakers and their Comparison in Modular Multilevel Converter Based-HVDC Transmission System

Electronics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1204
Author(s):  
Gul Ahmad Ludin ◽  
Mohammad Amin Amin ◽  
Hidehito Matayoshi ◽  
Shriram S. Rangarajan ◽  
Ashraf M. Hemeida ◽  
...  
Keyword(s):  
Solid State ◽  
High Voltage ◽  
Direct Current ◽  
Circuit Breaker ◽  
Transmission System ◽  
Simulation Software ◽  
Fault Current ◽  
Circuit Breakers ◽  
Hvdc Transmission ◽  
Dc Circuit Breakers

This paper proposes a new and surge-less solid-state direct current (DC) circuit breaker in a high-voltage direct current (HVDC) transmission system to clear the short-circuit fault. The main purpose is the fast interruption and surge-voltage and over-current suppression capability analysis of the breaker during the fault. The breaker is equipped with series insulated-gate bipolar transistor (IGBT) switches to mitigate the stress of high voltage on the switches. Instead of conventional metal oxide varistor (MOV), the resistance–capacitance freewheeling diodes branch is used to bypass the high fault current and repress the over-voltage across the circuit breaker. The topology and different operation modes of the proposed breaker are discussed. In addition, to verify the effectiveness of the proposed circuit breaker, it is compared with two other types of surge-less solid-state DC circuit breakers in terms of surge-voltage and over-current suppression. For this purpose, MATLAB Simulink simulation software is used. The system is designed for the transmission of 20 MW power over a 120 km distance where the voltage of the transmission line is 220 kV. The results show that the fault current is interrupted in a very short time and the surge-voltage and over-current across the proposed breaker are considerably reduced compared to other topologies.

scholarly journals The effects of transcranial direct current stimulation on gait in patients with Parkinson’s disease: a systematic review

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Fateme Pol ◽  
Mohammad Ali Salehinejad ◽  
Hamzeh Baharlouei ◽  
Michael A. Nitsche
Keyword(s):  
Systematic Review ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Randomized Clinical Trials ◽  
Cortical Excitability ◽  
Experimental Studies ◽  
Gait Rehabilitation ◽  
Direct Current Stimulation

Abstract Background Gait problems are an important symptom in Parkinson’s disease (PD), a progressive neurodegenerative disease. Transcranial direct current stimulation (tDCS) is a neuromodulatory intervention that can modulate cortical excitability of the gait-related regions. Despite an increasing number of gait-related tDCS studies in PD, the efficacy of this technique for improving gait has not been systematically investigated yet. Here, we aimed to systematically explore the effects of tDCS on gait in PD, based on available experimental studies. Methods Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach, PubMed, Web of Science, Scopus, and PEDro databases were searched for randomized clinical trials assessing the effect of tDCS on gait in patients with PD. Results Eighteen studies were included in this systematic review. Overall, tDCS targeting the motor cortex and supplementary motor area bilaterally seems to be promising for gait rehabilitation in PD. Studies of tDCS targeting the dorosolateral prefrontal cortex or cerebellum showed more heterogeneous results. More studies are needed to systematically compare the efficacy of different tDCS protocols, including protocols applying tDCS alone and/or in combination with conventional gait rehabilitation treatment in PD. Conclusions tDCS is a promising intervention approach to improving gait in PD. Anodal tDCS over the motor areas has shown a positive effect on gait, but stimulation of other areas is less promising. However, the heterogeneities of methods and results have made it difficult to draw firm conclusions. Therefore, systematic explorations of tDCS protocols are required to optimize the efficacy.

scholarly journals Magnetoactive elastomers for magnetically tunable vibrating sensor systems

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Tatiana I. Becker ◽  
Yuriy L. Raikher ◽  
Oleg V. Stolbov ◽  
Valter Böhm ◽  
Klaus Zimmermann
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Smart Materials ◽  
Excitation Frequency ◽  
Experimental Studies ◽  
Uniform Field ◽  
Sensor Systems ◽  
Ongoing Research ◽  
Amplification Ratio ◽  
Field Distortion

Abstract Magnetoactive elastomers (MAEs) are a special type of smart materials consisting of an elastic matrix with embedded microsized particles that are made of ferromagnetic materials with high or low coercivity. Due to their composition, such elastomers possess unique magnetic field-dependent material properties. The present paper compiles the results of investigations on MAEs towards an approach of their potential application as vibrating sensor elements with adaptable sensitivity. Starting with the model-based and experimental studies of the free vibrational behavior displayed by cantilevers made of MAEs, it is shown that the first bending eigenfrequency of the cantilevers depends strongly on the strength of an applied uniform magnetic field. The investigations of the forced vibration response of MAE beams subjected to in-plane kinematic excitation confirm the possibility of active magnetic control of the amplitude-frequency characteristics. With change of the uniform field strength, the MAE beam reveals different steady-state responses for the same excitation, and the resonance may occur at various ranges of the excitation frequency. Nonlinear dependencies of the amplification ratio on the excitation frequency are obtained for different magnitudes of the applied field. Furthermore, it is shown that the steady-state vibrations of MAE beams can be detected based on the magnetic field distortion. The field difference, which is measured simultaneously on the sides of a vibrating MAE beam, provides a signal with the same frequency as the excitation and an amplitude proportional to the amplitude of resulting vibrations. The presented prototype of the MAE-based vibrating unit with the field-controlled “configuration” can be implemented for realization of acceleration sensor systems with adaptable sensitivity. The ongoing research on MAEs is oriented to the use of other geometrical forms along with beams, e.g. two-dimensional structures such as membranes.

scholarly journals Analysis of a Cantilevered Piezoelectric Energy Harvester in Different Orientations for Rotational Motion

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1206 ◽  
Author(s):  
Wei-Jiun Su ◽  
Jia-Han Lin ◽  
Wei-Chang Li
Keyword(s):  
Theoretical Model ◽  
Resonant Frequency ◽  
Rotational Motion ◽  
Axial Load ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Experimental Studies ◽  
Piezoelectric Energy ◽  
Piezoelectric Cantilever ◽  
Tip Mass

This paper investigates a piezoelectric energy harvester that consists of a piezoelectric cantilever and a tip mass for horizontal rotational motion. Rotational motion results in centrifugal force, which causes the axial load on the beam and alters the resonant frequency of the system. The piezoelectric energy harvester is installed on a rotational hub in three orientations—inward, outward, and tilted configurations—to examine their influence on the performance of the harvester. The theoretical model of the piezoelectric energy harvester is developed to explain the dynamics of the system and experiments are conducted to validate the model. Theoretical and experimental studies are presented with various tilt angles and distances between the harvester and the rotating center. The results show that the installation distance and the tilt angle can be used to adjust the resonant frequency of the system to match the excitation frequency.

Analytical and Experimental Simulation of Loose Pedestal Dynamic Effects on a Rotating Machine Vibrational Response

1991 ◽  
Author(s):  
Pavel Goldman ◽  
Agnes Muszynska
Keyword(s):  
Excitation Frequency ◽  
Experimental Studies ◽  
Experimental Simulation ◽  
Physical Parameters ◽  
Vibrational Response ◽  
Rotating Machine ◽  
Qualitative Pattern ◽  
The Impact ◽  
Good Agreement ◽  
Periodic Changes

Abstract This report presents experimental, analytical, and numerical results describing vibrational phenomena in a rotating machine with one loose pedestal. The loose-pedestal machine rotor vibrations represent unbalance-related excited vibrations of synchronous and fractional subsynchronous regimes. In this study the loose-pedestal machine is first simulated by a simple vibrating beam excited by a shaker mounted on it. The shaker simulates an unbalanced machine rotor. The beam occasionally enters in contact with the foundation. The excited vibrations are modified by impacting occurrences, and by periodic changes in system stiffness. A new model of the impact has been developed. The results of analytical and experimental studies stand in a good agreement. They illustrate the existence of the synchronous regime and several subsynchronous fractional regimes in various excitation frequency ranges. The analysis adequately predicts the occurrence of these regimes and determines the physical parameters affecting them. The analytical and experimental results are then compared with the responses of experimental rotor rig with one bearing pedestal looseness. They show the same qualitative pattern.

Abstract 60: Inducible Arrythmogenicity of Direct Current Electroporation Ablation: Insight from a Series of Acute Canine Studies

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Alan Sugrue ◽  
Chance Witt ◽  
Christopher V DeSimone ◽  
Deepak Padnanabhan ◽  
Ammar Killu ◽  
...  
Keyword(s):  
Direct Current ◽  
Superior Vena ◽  
Pulmonary Veins ◽  
Pulse Length ◽  
Experimental Studies ◽  
Tissue Destruction ◽  
Ecg Gating ◽  
Actual Mechanism ◽  
Membrane Poration ◽  
Current Energy

Background: The use of direct current electroporation has the potential for significant utility because of its non-thermal approach to tissue destruction. However, the fear of inducibility of cardiac arrhythmias (particular ventricular fibrillation) when using electroporation remains of concern due to membrane poration and ion flux during periods of vulnerability occurring in ventricular repolarization. Objectives: Critically examine the incidence of arrhythmias in a series of acute canine studies to retrospectively determine cause and safe electoporative dosing margins. Methods: We performed electroporation ablation in 6 acute canine studies. These were experimental studies performed at sites critical in arrhytmogenesis. Sites included the pulmonary veins, left atrial appendage, superior vena cavae, right atrium and ventricle. Electroporation was delivered using an ECG gating algorithm so that QRS complexes are tagged and direct current energy is not delivered during the vulnerable portion of the T wave. Results: In 6 acute canine experiments, we delivered a total of 62 electroporation applications for ablation purposes. The average electroporation dosage delivered involved an average of 1427 Volts (range 750-3000 V), Pulse length of 100 ms, and number of pulses of 20.2 (range 10-100). AF was induced in 27.4% of electroporiatve applications. Atrial flutter/tachycardia occurred in 8.1%. VF occurred in only one application at a location of the left superior pulmonary vein. Conclusion: These data suggest that induction of VF is relatively uncommon with ECG gating and highlight its importance when using this modality. However, the induction of AF occurs with higher frequency. The actual mechanism as to why this occurs requires further systematic study.

scholarly journals COHERENT PROPAGATION OF LASER BEAMS IN MCF FIBERS

2019 ◽  
Vol 47 (1) ◽  
pp. 21-23
Author(s):  
A.A. Balakin ◽  
S.A. Skobelev ◽  
A.V. Andrianov ◽  
E.A. Anashkina ◽  
A.G. Litvak
Keyword(s):  
Solid State ◽  
Optical Fibers ◽  
High Efficiency ◽  
Radiation Power ◽  
Experimental Studies ◽  
Pump Energy ◽  
Total Power ◽  
Beam Power ◽  
Self Focusing ◽  
Weakly Coupled

The successful development of fiber-optic technologies in recent decades has stimulated research on the replacement of components of solid-state laser systems with fiber components, which can drastically change the attractiveness of the corresponding applied developments. Yielding on the energy characteristics of solid-state systems, fiber lasers and nonlinear optical devices have high efficiency of conversion of pump energy to radiation energy associated with waveguide geometry, high quality of the spatial profile of the laser beam, as well as low cost, compactness, lack of alignment in work process. Note that the maximum achievable radiation power in a single fiber is limited primarily by the process of self-focusing, which leads to fiber damage. The use of a multi-core fiber (MCF), consisting of identical equidistant weakly coupled optical fibers, makes it possible to realize initially coherent propagation of laser radiation with a total power noticeably higher than it can be transmitted in a single optical fiber. However, as theoretical and experimental studies have shown, such systems have its own critical power (Balakin et al., 2016) whereby the self-focusing of the quasihomogeneous distribution of the wave field and its separation into a set of incoherent structures occurs. Therefore, we have considered a small-sized optical system of 2N identical weakly coupled optical fibers arranged in a ring (Balakin et. al., 2018). In such systems, it is possible to find stable distributions of intense wave beams, which allow coherent radiation transport over long distances. The total radiation power in the found distributions can significantly (up to 2N times) exceed the critical self-focusing power in continuous media. This manifests itself most clearly for the distribution of un ~ (-1)n with antiphase fields in neighboring waveguides, which is stable at an arbitrary wave beam power. Direct numerical simulation of a nonlinear wave equation confirms the stability of the field distributions found. The research was supported by the RAS Presidium Program «Nonlinear dynamics: fundamental problems and applications».

scholarly journals Computer-Integrated Device for Acidity Measurement Monitoring in Greenhouse Conditions with Compensation of Destabilizing Factors

2020 ◽  
Vol 19 (4) ◽  
pp. 243-253
Author(s):  
Ivan S. Laktionov ◽  
Oleksandr V. Vovna ◽  
Maryna M. Kabanets ◽  
Iryna A. Getman ◽  
Oksana V. Zolotarova
Keyword(s):  
Experimental Studies ◽  
Effect Of Temperature ◽  
Synthesis Methods ◽  
Random Component ◽  
Monitoring And Control ◽  
Measuring Device ◽  
Measurement Monitoring ◽  
Cloud Computing Service ◽  
Computerized Monitoring ◽  
Integrated Device

The purpose of the article is to improve procedures of computerized monitoring and control of technological processes of growing greenhouse crops by substantiating methods of improving the accuracy of computer-integrated devices for measuring irrigation solution acidity. The article solves the topical scientific and applied problem of determining the conversion characteristics of computerized acidity monitoring systems with integral and differential assessment of their metrological parameters. Theoretical and experimental studies were obtained based on structural-algorithmic synthesis methods for information-measuring systems; methods of mathematical planning of experiments; regression analysis of experimental data and the concept of uncertainty. The computerized acidity meter was implemented on the basis of an ion-selective pH electrode, Arduino microprocessor platform, and ThingSpeak cloud computing service. The relative total boundary uncertainty of acidity measurement is not more than ±1.1 %. Methods of compensating of the random component of uncertainty based on the median filtering algorithm and additional uncertainty from the destabilizing effect of temperature were introduced when implementing the measuring device. Promising areas of priority research to improve the efficiency of the developed computerized acidity meter were justified. The developed device can be used in the complex automation of greenhouse cultivation processes. The developed and implemented measuring tool can be used when planning agricultural operations in greenhouse conditions.

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