Problem Of Compensation Research Articles

INCREASING THE SECRECY OF TRANSMISSION INFORMATION BASED ON COMBINED RANDOM CODING

Context. The task of increasing the secrecy of information transmission based on combined random coding is considered. Theobject of research is the integration processes of stochastic, block and timer coding.Objective. The aim of the article is to develop a method of increasing the secrecy transmission based on combined random coding.Method. The method of increasing the secrecy of information transmission based on combined random coding with three stepsof code converters: internal, intermediate and external is proposed. The internal converter is implemented based on stochastic coding with various numbers of random code combinations. The number of random combinations depends on the probability of the character of the symbol in the message text. The information secrecy of the transmission is ensured by equalizing the probabilities of the occurrence of code combinations from the output of the statistical coder. Intermediate coding is implemented using a noise immunity block code. Information secrecy and noise immunity leads to the increasing the length of the code block at each stage of coding, which reduces the code rate. To solve this problem, an external converter based on timer coding is used. At this stage, binary combinations are converted into timer signal structures, which allows for the implementation of a structural transmission secrecy, increase the code rate and improve noise immunity. When the stochastic encoding and a timer used codebooks.Results. The developed method of combined random coding allows to increase the main indicators of noise immunity: interferenceprotection, information and structural secrecy.Conclusions. The proposed method of combined random coding allows to eliminate the main disadvantages of stochastic coding,in which the choice of the number of random code combinations does not take into account the entropy of the discrete source of information. For solving this problem, it was proposed to use different number of random combinations, in view of the probability of an alphabet symbol appearing in the text. From the theoretical point of view, this will allow the output of the statistical coder to form a stream of combinations with equal probabilities of occurrence. Due to the usage of timer signal constructions, the problem of redundancy compensation is solved, which appears during stochastic and noise-immune coding.

Experimental identification of the impact of sectional satellite wheels on the load distribution in the meshing of the planetary gear in mining machines

Abstract This article attempts to solve the problem of load compensation in mesh planetary gearing, with the innovative design idea, resulting from the increased plasticity of the planet wheels (satellite). The cognitive main objective of the experimental work was carried out to identify the comparative effect of the split narrow planet gears, on the load distribution on the length of the teeth of the planet gears of the central wheel of the planetary gear. Achieving this aim, in addition to in-depth analysis, requires experimental research on a specially-built test stand and simulation tests on a solid model of the transmission using the finite element method (FEA). This article presents the concept of a novel test stand, design methodology and research on the influence of the sectional satellite wheels on the load mesh of planetary gears in mining machines.

A Reliable Gravity Compensation Control Strategy for dVRK Robotic Arms With Nonlinear Disturbance Forces

External disturbance forces caused by nonlinear springy electrical cables in the Master Tool Manipulator (MTM) of the da Vinci Research Kit (dVRK) limits the usage of the existing gravity compensation methods. Significant motion drifts at the MTM tip are often observed when the MTM is located far from its identification trajectory, preventing the usage of these methods for the entire workspace reliably. In this paper, we propose a general and systematic framework to address the problems of the gravity compensation for the MTM of the dVRK. Particularly, high order polynomial models were used to capture the highly nonlinear disturbance forces and integrated with the Multi-step Least Square Estimation (MLSE) framework. This method allows us to identify the parameters of both the gravitational and disturbance forces for each link sequentially, preventing residual error passing among the links of the MTM with uneven mass distribution. A corresponding gravity compensation controller was developed to compensate the gravitational and disturbance forces. The method was validated with extensive experiments in the majority of the manipulator's workspace, showing significant performance enhancements over existing methods. Finally, a deliverable software package in MATLAB and C++ was integrated with dVRK and published in the dVRK community for open-source research and development.

A convex formulation for voltage unbalance compensation problem on hybrid microgrids

A convex formulation for voltage unbalance compensation problem on hybrid microgrids

Design of DOB-based riveting force controller for dual-machine horizontal drilling and riveting system

A dual-machine horizontal automatic drilling and riveting system for aircraft panel assembly is presented in this paper. Two cooperative machines are adopted, like a two-robot system, to achieve the unobstructed workspace, so it can be applied in an efficient assembly line. Different from the current deign wisdom to ensuring the riveting accuracy by increasing the machine stiffness, which detrimentally results in higher masses to be moved and sophisticated reinforcements being used, this paper proposes a disturbance observer (DOB) based design method of riveting force controller for adaptive riveting with high accuracy driven heads, reducing the dependence of automatic riveting on high stiffness of machine. This method simplifies the force-induced deformation error compensation problem to a force control problem, which has rarely been studied before in literature. The separate layout leads to weak machine stiffness in the whole workspace and the stiffness varies with machine pose greatly, which makes it difficult to establish an accurate force-induced deformation error compensation model. To make the riveting machine precisely generate the desired force under such stiffness-varying conditions, a robust control algorithm is designed: the disturbance observer is introduced to address the robust stability against model parameter variance caused by the change of system stiffness with pose, and the feedforward controller can achieve the high-bandwidth force control to ensure the riveting efficiency. The model identification experiments are carried out for different machine stiffness. Validation riveting experiments have been conducted to verify the proposed controller on the dual-machine riveting system. The results show that, compared with previous displacement control, the proposed force controller can ensure the consistency of driven heads through accurate force control.

Research on Angle and Stiffness Cooperative Tracking Control of VSJ of Space Manipulator Based on LESO and NSFAR Control

With the increase in on-orbit maintenance and support requirements, the application of space manipulator is becoming more promising. However, how to control the vibration generated by the space manipulator has been a difficult problem to be solved. The advent of variable stiffness joint (VSJ) has brought about a dawn in solving this problem. But how to achieve coordinated control of joint angle and stiffness is still a problem to be solved, especially when considering system model parameter uncertainty, unknown disturbance and control input saturation. In order to realize the controllable attenuation of the vibration of the space flexible manipulator based on the variable stiffness joint, the dynamic model of the variable stiffness joint was constructed. Then the linear transformation and feedback linearization method are used to transform its complex nonlinear dynamic model system into a pseudo-linear system containing aggregate disturbance and input saturation constraints. This paper constructs a linear extended state observer (LESO) for estimating the state of unknown systems in pseudo-linear systems. Based on the idea of state feedback control, a Neural State Feedback Adaptive Robust (NSFAR) control is constructed by using Radial Basis Function Neural Network. The adaptive input saturation compensation control law is also designed by using Radial Basis Function Neural Network to deal with the input saturation compensation problem. The ultimate uniform bounded stability of the constructed system is proved by the stability analysis based on Lyapunov function. Finally, the effectiveness and superiority of the constructed tracking algorithm are verified by compared simulation and semi-physical experiment.

An Effective Autofocus Method for Fast Factorized Back-Projection

Back-projection (BP) is a reliable synthetic aperture radar (SAR) imaging algorithm because of its high-resolution and strong adaptability. However, it is hard to implement because of its high computational complexity. Fast factorized BP (FFBP) is a new way to fix this problem. Like traditional BP, FFBP is compatible with arbitrary flight paths if the track deviations are measured within fractions of a wavelength. However, when the motion information is not accurate enough, autofocus become an important way to get well-focused images. In this paper, we present an effective autofocus method for FFBP to solve the imaging problem caused by platform’s motion errors. First, an image quality evaluation function with unknown phase error based on image sharpness for FFBP is established. Then, the phase error computation for autofocus is modeled as an optimization problem. Second, the coordinate descent (CD) and secant processing are introduced to the maximum image sharpness problem. The proposed method keeps the rapid imaging performance of FFBP and solves well the motion error compensation problem. In the end, simulated data and real data were used to verify the effectiveness of the proposed algorithm.

Generalized stable inverse Q filtering

The conventional stable inverse Q filtering method overcomes the instability of the inverse Q filtering and can effectively perform amplitude compensation and phase correction. However, its shortcoming is that it cannot solve the problem of excessive compensation for shallow seismic records and insufficient compensation for deep seismic records. The essence is that the compensation bandwidth and intensity of the amplitude compensation operator cannot be adjusted. We propose a generalized stable inverse Q filtering method. By introducing a parameter into the stable amplitude compensation operator based on stabilization factor, the method can flexibly and effectively handle the compensation intensity and frequency bandwidth to achieve high resolution and high signal-to-noise ratio seismic data. The test results of theoretical synthetic seismic data and real seismic data show that this method has unique value in frequency band selection of amplitude compensation according to the quality of seismic data, which can improve the resolution and get high signal-to-noise ratio seismic data.

Time delay compensation for nonlinear bilateral teleoperation: A motion prediction approach

This paper addresses the time delay compensation problem for nonlinear teleoperation system. A novel motion prediction approach is proposed based on a state observer with a cascade structure. The actual positions of master robot are estimated on the slave side by using delayed information of measurements. The prediction errors remain bounded under an appropriate set of assumptions for the system uncertainties. Moreover, an essential theorem for slave controller design is proposed to demonstrate performance recovery of the closed-loop system with cascade observer. By using the predictions, the forward time delay is effectively compensated when we design the controller of slave robot. Simulations are performed to verify the effectiveness of proposed method. The prediction results are highlighted through comparing with other two kinds of cascade predictors.

매장문화재 발굴 제도의 문제점과 개선방안

매장문화재 발굴 제도의 문제점과 개선방안

Multi‐objective grey wolf optimizer algorithm for combination of network reconfiguration and D‐STATCOM allocation in distribution system

The distribution flexible alternating current system (D-FACT) devices are being increasingly placed in the distribution system due to their several practical and environmental benefits. In this work, a novel grey wolf optimizer (GWO) algorithm as a meta-heuristic technique is applied to solve the reconfiguration problem, the installation of distribution static compensator (D-STATCOM) problem, and the combination of these two problem. The aim of this research is to diminish the total power loss and the load-balancing (LB) index of the radial distribution system. First, the index vector (IV) method is employed to suggest the candidate busses for D-STATCOM allocation. Then, the GWO algorithm is applied to establish the locations and sizes of the D-STATCOM from the candidate busses. An overall accurateness and consistency of the proposed GWO algorithm has been validated and experienced on a 33-bus, a 69-bus, and a real-time 31-bus radial distribution system, India with three kinds of load levels. In addition, the proposed method results are ideal as compared with other intellectual methods like genetic algorithm (GA) and fuzzy GA.

Geometric modelling of thin-walled blade based on compensation method of machining error and design intent

Due to the low stiffness of the thin-walled aero-engine blade milling process, the machining errors cannot match the tolerance requirements and thus limit the aerodynamic performance. Previous research mainly focused on developing the compensation method to decrease the errors in concave and convex surfaces milling processes through controlling the tool path. However, the solutions on solving the leading and trailing edges machining errors are lacking. This paper first utilizes the geometric modelling framework of the blade to solve the machining error compensation problem. Furthermore, the presented solution could be not only suitable for the concave and the convex surfaces milling processes, but also capable for decreasing the leading and the trailing edges machining errors. A novel geometric modelling of the blade is developed in this paper, including the reconstruction procedure of the concave and the convex curves based on the secant compensation method, and the construction strategy for the leading and trailing edges is derived through the design tangents of the leading and trailing edges points. The validation demonstrates that for the thin-walled part milling process, the proposed secant compensation method could decrease the machining errors significantly (the maximum and the average errors are reduced to 31.7% and 23.8%, respectively). And for the blade milling process, the average errors of concave and convex surfaces are reduced to 25.1% and 14.3%, respectively. The average errors of leading and trailing edges are reduced to 29.7% of uncompensated machining process.

Application of Modified Impedance Matrix to Determine an Initial Solution for Reactive-Power Compensation Problem

As an optimization problem, reactive-power compensation (RPC) in distribution networks has variety of technical and economical objectives and constraints. In order to solve the RPC problem, classic and heuristic methods have been applied. In distributed networks with large amounts of equipment, the RPC has a large dimension which could be a challenge for the aforementioned methods. So, having an initial guess or solution for buses that are suitable for compensator installation, lessens the mentioned challenge and thus improves performance of the solution procedures. Applying extended impedance matrix, this paper proposes a method to determine initial solution for the RPC problem. “Extended” means loads connected to buses are included in the impedance matrix. Inclusion of loads in the matrix gives more realistic initial solutions. The rationale behind it is that buses with more loads usually need more reactive composition. Two ranking lists of the buses that could be nominated for RPC have been considered in this paper: One list is obtained by the proposed method, and the other by the sensitivity analysis. Comparison of the mentioned lists in two typical distribution systems shows acceptable performance of the proposed method.

A Four-Winding Inductive Filtering Transformer to Enhance Power Quality in a High-Voltage Distribution Network Supplying Nonlinear Loads

This paper solves the problem of reactive power and harmonics compensation in a high-voltage (HV) distribution network supplying nonlinear loads. An inductive filtering (IF) approach where passive filters connect to the filtering winding of a four-winding inductive filtering transformer (FW-IFT) is presented to enhance the power quality of the public grid. This method can not only greatly suppress harmonic currents of the medium and/or low-voltage (LV) side, but also prevent them from flowing into the public grid. The new main circuit topology, where the FW-IFT has specific filtering winding by adopting the ampere-turn balance of the transformer, is presented. On the basis of the structure of the FW-IFT, the magnetic potential balanced equation and inductive filtering technology, its equivalent circuit and mathematical model are established, and the filtering performances are analyzed in detail. Simulation and experimental results rated at SN-10/0.38 of the FW-IFT are presented to prove the efficacy of the comprehensive enhancement of power quality on the grid side.

A space cutter compensation method for multi-axis machining using triple NURBS trajectory

Aiming at the space cutter compensation problem for multi-axis machining of complex surfaces, firstly, a space cutter compensation method for multi-axis machining based on triple NURBS (non-uniform rational B-splines) trajectory is proposed, which can describe the machining trajectory information more completely and accurately, and is also expected to achieve dynamic radius and length compensation of multi-axis machine’s space cutter. Secondly, for the generation of NURBS trajectory of cutter axis vector and cutting contact vector, three error sources in NURBS curve offset process are analyzed in detail. The error scaling problem is especially pointed out, and a NURBS curve fast offset method with user-definable tolerance is proposed. Finally, the specific calculation method and system implementation scheme of space cutter radius and length compensation using triple NURBS curve trajectory are given. The effectiveness of the proposed space cutter compensation method was verified by simulation and machining experiments.

Iterative Detection and Phase-Noise Compensation for Coded Multichannel Optical Transmission

The problem of phase-noise compensation for correlated phase noise in coded multichannel optical transmission is investigated. To that end, a simple multichannel phase-noise model is considered and the maximum a posteriori detector for this model is approximated using two frameworks, namely factor graphs (FGs) combined with the sum-product algorithm (SPA), and a variational Bayesian (VB) inference method. The resulting pilot-aided algorithms perform iterative phase-noise compensation in cooperation with a decoder, using extended Kalman smoothing to estimate the a posteriori phase-noise distribution jointly for all channels. The system model and the proposed algorithms are verified using experimental data obtained from space-division multiplexed multicore-fiber transmission. Through Monte Carlo simulations, the algorithms are further evaluated in terms of phase-noise tolerance for coded transmission. It is observed that they significantly outperform the conventional approach to phase-noise compensation in the optical literature. Moreover, the FG/SPA framework performs similarly or better than the VB framework in terms of phase-noise tolerance of the resulting algorithms, for a slightly higher computational complexity.

Algorithms of adaptive tracking of unknown multisinusoidal signals in linear systems with arbitrary input delay

SummaryThe problem of adaptive tracking control is addressed for the class of linear time‐invariant plants with known parameters and arbitrary known input delay. The reference signal is a priori unknown and is represented by a sum of biased harmonics with unknown amplitudes, frequencies, and phases. Asymptotic tracking is provided by predictive adjustable control with parameters generated by one of three designed adaptation algorithms. The first algorithm is based on a gradient scheme and ensures zero steady‐state tracking error with all signals bounded. The other two algorithms additionally involve the scheme with fast parametric convergence improving the closed‐loop system performance. In all the algorithms, the problem of delay compensation is resolved by special augmentation of tracking error. The adjustable control law proposed do not require identification of the reference signal parameters.

Error Compensation for 3D Digital Laser Scanning Data Based on the Surface of Aluminum Coated F-12 Aramid Plain Weave Fabric and a Test of Configuration for Large Balloon

The measurement of the configuration parameters for the large balloon is an important content, including volume, surface area and specific size under a certain internal pressure. Non-contact measurement techniques using laser scanning have the advantage of fast acquiring large numbers of points. However, compared to their contact-based counterparts, these techniques are known to be less accurate. Furthermore, this accuracy depends on different parameters such as materials properties, surface texture, product color, etc. The large balloon is made by aluminum coated F-12 aramid plain weave fabric pieces. The digitizing errors for high-speed 3D digital laser scanning data based on the surface of F12 fabric material are analyzed and characterized in this paper. With error characterisation, an empirical model is obtained relating the errors to the influencing factor. Establishing a reasonable test scheme and using the technology of laser scanning, the spatial information of the surface for large balloon can be obtained quickly. The empirical formula is used to compensate for 3D laser scanning data of large balloon. The problem of compensation for 3D laser scanning data for improved test accuracy is addressed. The more accurate parameters of the configuration for large balloon are quickly obtained. This provides a method for the rapid, high-efficiency and high-precision test of configuration for large balloon.

RESEARCH OF THE MODES OF FULL COMPENSATION OF REACTIVE POWER IN A THREE-PHASE POWER SUPPLY SYSTEM

Introduction The article is devoted to the issues of current balancing and reactive power compensation in a three-phase power supply system. Optimal in all these respects is the mode of full compensation of reactive power, by which we mean such a symmetrical mode, in which only active power is consumed from the source. The task of calculating the mode of full reactive power compensation is non-linear and can be solved using non-linear optimization methods based on the adopted parameters and optimization criteria. The objective of the article is to develop a visual model of the power supply system with an unbalanced load, in which current balancing and reactive power compensation is performed using a symmetrical-compensating device, which parameters are determined using search non-linear optimization tools and modern computer mathematics software packages. The purpose of the article is to research the modes of full compensation of reactive power in a three-phase power supply system with a linear asymmetric load in order to identify the ambiguity of solving the problem of synthesizing parameters of a reactive power compensator. Methodology of research consists in the development of a visual model of a power supply system that feeds unbalanced load. As a symmetrical compensating device, capacitors connected between the phases of the transmission line are used. The model is controlled by a program that launches the model and performs optimization and selection of optimization variable values. The optimization values are the capacitors of the symmetry-compensating device. The optimization criterion is a spherical metric consisting of the reactive powers of each source of electricity. Results lead depending on the choice of the initial values of the optimization variables, the optimization process enters two modes of full compensation of reactive power – main and additional. The main mode is characterized by small values of capacitors and small values of currents, and in the additional mode, these values of the system and operational parameters reach extremely large values that are unacceptable for practical use. Originality lies in the fact that in terms of optimization theory this means that there is no global optimum in the solution of the problem of full compensation, however, there are two local optimums. Both modes are stable, as evidenced by modeling on the SPS-model of the system in the time domain in the space of state variables. Practical significance of the work lies in the fact that when designing a microprocessor system that optimizes the operating mode of the power supply system, it is necessary to envisage the situation of additional mode.

Pengaruh Kompensasi Terhadap Kinerja Karyawan Pada Perusahaan Warunk Bendito Manado

This study aims to determine the effect of compensation on employee performance. With the problem of compensation for the performance of employees at the Warunk Bendito Manado company. The sample taken was 34 people from a total of 34 employees in the company. In this study used a type of quantitative research. Technique data collection uses questionnaires to respondents, making observations and interviews. The technique used in data analysis is to use simple regression statistics with SPSS version 22.00 to test the significance of the relationship between variables and to measure the magnitude of the effect that occurs on compensation variables and employee performance variables. From the results of t test and correlation, it can be seen that the results of tvalue < ttable have a negative influence. The results of the R square correlation value have a weak correlation. Based on the results of calculations from the study it can be seen that the compensation variable has a negative effect on employee performance variables.