Search

In recent years, a special attention is paid to grid connected multilevel converters. These converters have specific use in industry in a high power, medium-voltage and highvoltage applications. This paper presents new control algorithm for single-phase AC/DC modular multilevel converter with target application as a traction converter connected directly to trolley wire. The proposed control strategy presents resonant controllers for converter current control with fundamental frequency adaptation. The fundamental frequency estimation and voltage synchronization is based on Second Order General Integrator Phase Locked Loop (SOGI-PLL). Furthermore, this paper presents robust voltage balancing technique for multilevel converter based on energy calculation of DC-link capacitances. It provides voltage balancing of multilevel converter cells with unbalanced load. The resulting control algorithm has low total harmonic distortion of converter trolley current even under unbalanced load condition. The algorithm was experimentally verified on the low voltage laboratory prototype with 3 H-bridge cells. [ABSTRACT FROM AUTHOR]

Aiming at the problem of many illegal individuals or units adopting various methods to steal electricity under the current power environment, this paper proposes an anti-theft load identification method based on Long Short-Term Memory (LSTM). First, screen users with electricity theft and abnormal behaviors, analyze the collected voltage, current and electric energy by the electricity theft detection equipment, and use the LSTM neural network algorithm to judge the characteristics of the screened suspect users, and initially determine users with abnormal behaviors. Then comprehensively use GPS equipment to send the comparison results of the host to the master station in real time. The master station only needs to be responsible for a small amount of post-processing and statistical analysis, and intelligent diagnosis based on the characteristics of the electricity theft, so that the user can perceive the electricity theft incident on the spot in real time to avoid the loss of electricity bills, and provide a strong theoretical basis for the intelligent operation and maintenance of power companies. [ABSTRACT FROM AUTHOR]

In this paper, application of the Surface Current Method (SCM) in analysis and optimization of electromechanical devices is proposed. SCM is one of the numerical techniques in electromagnetic field analysis. In SCM, only magnetic boundaries are subdivided against Finite Element Method (FEM) which is subdivided into all of domains; therefore, the calculation resources of SCM are much lower than FEM. SCM with low-calculation resource is one of the best numerical techniques for magnetic devices' optimization. In this paper, using SCM, three electromechanical systems have been optimized based on minimization of weight per force. Verification of simulation results is done by FEM. [ABSTRACT FROM AUTHOR]

Electric shock is the pathophysiological consequence caused by the electric current flowing in the human body. The consequences, for a specific current path, depending on the magnitude and the duration of the current through the human body. Many accidents are preventable by taking appropriate measures. This paper discusses a method for the elimination of the electrocution hazard. The method is applied in devices/tools/equipments surrounded by a metal enclosure and is implement through measurements of electric and magnetic fields. Measuring the produced "electric field" near the metal shell one can detect the loss of proper grounding. Similarly, a broken neutral connection can be detected by measuring the "magnetic field" around the tool. It is proven that the loss of grounding of the shell or the disconnection of the neutral wires alters the electric and magnetic field in a countable manner. For that, the paper discusses a constructed device that, when is placed in proximity to the metal shells of electron appliances, prevents injuries. It detects the variations in electric and magnetic fields and displays a warning signal to indicate the hazard. [ABSTRACT FROM AUTHOR]

As a common electrical fault causing fire, current overload results in some trace evidences on the wire. However, most of relative evidences, such as insulating layer, metal core, are likely to be destroyed or disturbed by fire. The majority of wire evidences from fire are asked to test melted breakpoints marks of the wire. Thus, it is significant to clearly reveal the metallographic features of melted breakpoint mark for wire overloading for fire investigators. This paper selected two kinds, single-core and multi-cores, 1.5 mm 2 copper wires to make melted breakpoints with 100A current overload. Then, this paper did some research on the fire heat influence on the microstructure of melted breakpoints. Experimental results indicated that the metallographic structure of the melted breakpoint mark caused by current overload was significantly different from that of melted mark caused by fire and short circuited melted mark. As for melted breakpoint marks of copper wire overloading, the most distinctive feature of the metallographic structure was dendritic segregations existing. [ABSTRACT FROM AUTHOR]

The present paper investigates the axial and transverse coupled vibration law of deep-water top-tensioned riser (TTR) under the combined effects of the internal fluid flow and external wave and current loads. The paper aims to derive nonlinear vibration equations of deep-water riser, which account for the coupling of axial and transverse vibration including vortex-induced vibration, the internal fluid flow and the changes of the riser cross-sectional area caused by internal and external pressure alteration. With all factors above involved, a coupling vibration model is developed for deep-water riser. Based on the numerical model established, the influences of internal flow and the changes of internal flow velocity on the coupled vibration of deep-water riser are analyzed. In addition, parameter excited dynamic response of the riser under complex environment is also studied. The comprehensive analysis demonstrates that the internal flow can greatly change the vibration characteristics of the riser, comparing with a hollow one. The results lend support to the conclusion that the vibration of riser is not sensitive to changes of the internal flow velocity. [ABSTRACT FROM AUTHOR]

The paper presents the mobility calculation, geometry and kinematics of a robot arm. It is a serial robot whose main spatial kinematic chain consists of four revolute joints. Four continuous current electric motors are used for driving the serial robot. We have used matrix calculus for the kinematic analysis of the serial robot arm so that we obtained the three Cartesian coordinates of the characteristic points according to the four independent angular parameters. By means of reversed kinematics, when the three coordinates of the end effector point are imposed, we deduced three non-linear equations with four angular unknown parameters, which proves the robot's redundancy (an extra unknown parameter). Regarding the prehension mechanism, the kinematic schema with two symmetrical parallelograms has been presented, which ensures the circular translational motion of the two fingers. [ABSTRACT FROM AUTHOR]

This paper describes the application of the theory of characteristic modes to excite a conducting cylinder representing the chassis of a rocket. Mode excitation is achieved by cutting H-shaped slots on the cylinder at specific locations where the maximum of modal current distribution occurs. The L-matching network is designed to match the impedance of the slots to the input coaxial cable. Finally, the proposed concept is verified during manufacturing and measurement. It is shown that the measured results are in excellent agreement with the simulation. [ABSTRACT FROM AUTHOR]

This paper proposes an analysis of the calculation of voltage and current ripples, voltage stresses, switching device power, and switching loss in the Z-source inverter. In this paper, the formulas of the inductor current ripple, capacitor voltage ripple, voltage stress on the devices and capacitors, switching device power and switching loss, are presented. Computing these formulas will help us greatly in the performance improvement of the Z-source inverter, and in this paper, a detailed analysis of the main formulas is presented. Simulation results are also given to confirm the analysis. [ABSTRACT FROM AUTHOR]

Electrosurgery uses electric current to heat, coagulate and ligate tissue. The current flow induces a voltage due to the bio-impedance of the tissue. The flow of the current should be controlled precisely to avoid tissue damage by overheating. The control requires the proper mathematical formulation of the current and voltage relationship. This mathematical description can be explained as a dynamical system. It is composed of linear time invariant (LTI) system and/or the static nonlinearity. The in-depth understanding of the system behaviour requires parameter estimation of the LTI block and the nonlinearity. It is often done stepwise by identifying the best linear approximation (BLA) to fit the whole combination of LTI block and nonlinearity. In this paper, we study the potential discrimination of a block-oriented model between femoral, mesentery, renal and tendon tissue. The estimated system fits up to 99.84% accurately with the measured signal after optimization for the electrosurgery data of Covidien Inc. The parameters exhibit that a weak nonlinearity exists in the measurement data. Finally, the fractional order LTI systems are explored to cope with the diffusion due to the generated heat. • Mathematical formulation of the current-voltage relationship of bipolar electrosurgery • Differentiation among different types of tissue through the best linear approximation • Parametric study as the W-H system fits up to 99.84% on real-life electrosurgery data • Fractional-order LTI system is explored to cope with diffusion due to generated heat [ABSTRACT FROM AUTHOR]

This paper presents the photovoltaic system connected to electrical grid with the presence of non-linear load (three-phase rectifier) in the first case, then tries to minimize the harmonic currents generted by this non-linear load with applying the technology of the shunt active power filter (SAPF). In this work, we use the MPPT controller for the Boost converter, the PWM command for the three-phase inverter and, with regard to the shunt active filter, we have chosen the PQ theory for harmonic currents identification, and hysteresis control for the inverter, and the PI controller for the DC bus. The simulation results obtained show the efficiency of this moderne technique given the waveforms of the currents obtained which are very close to the sinusoid shape, and the values of the calculated total harmonic distortion (THD) rates which are in the standard norms. [ABSTRACT FROM AUTHOR]

Fault prognosis is one of the key techniques for prognosis and health management, and an effective fault feature can improve prediction accuracy and performance. A novel approach of feature extraction for fault prognosis based on fault trend analysis was proposed in this paper. In order to describe the ability of tracking fault growth process, definitions and calculations of fault trackability was developed, and the feature which had the maximum fault trackability was selected for fault prognosis. The vibration data in bearing life tests were used to verify the effectiveness of the method was proposed. The results showed that the trackability of energy entropy for bearing fault growth was the maximum, and it was the best fault feature among selected features root mean square (RMS), kurtosis, new moment and energy entropy. The proposed approach can provide a better strategy for fault feature extraction of bearings in order to improve prediction accuracy. [ABSTRACT FROM AUTHOR]

In this paper, the effect of a single pulsed electric current on the springback reduction of UHSS is investigated by experiments. To do this, a current pulse generator and a bending setup were designed and manufactured. V-bending tests of the 1180 grade steel sheet under a pulsed electric current were then carried out for evaluating springback reduction. The electric pulse was applied to the specimen with constant amplitude of electric current and duration time after the specimen was deformed. The influence of the two adjustable electrical parameters pulse duration and current density on springback was analyzed. The experimental results showed that springback angles are sharply decreased with increasing current densities and pulse durations. [ABSTRACT FROM AUTHOR]

This paper presents a new optimization tool for analog circuit design. The proposed tool is based on the robust version of the differential evolution optimization method. Corners of technology, temperature, voltage and current supplies are taken into account during the optimization. That ensures robust resulting circuits. Those circuits usually do not need any schematic change and are ready for the layout. The newly developed tool is implemented directly to the Cadence design environment to achieve very short setup time of the optimization task. The design automation procedure was enhanced by optimization watchdog feature. It was created to control optimization progress and moreover to reduce the search space to produce better design in shorter time. The optimization algorithm presented in this paper was successfully tested on several design examples. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a long-term filed data collection system from a person living house required for designing a life pattern sensor. The life pattern sensor is an activity recognition sensor both for measuring electric power consumption and detecting use of electronic devices by utilizing high-frequency electrical current waveform as a signature of each device. A prototype of the life pattern sensor has been developed and evaluated in five homes. The results show the life pattern sensor measured power consumption within 1% error and identified uses of devices with over 95% accuracy. The capability of the sensor is enough for realizing home energy management system. The long-term data collection system is constructed so as to collect annotated field data for sophisticating the sensor in practical level. In this paper, the overview of the data collecting system and discussion about the following questions based on the field data: [1.] Can current waveform be in stable at any conditions in a house? [2.] Can sequence of electronic devices describe residents’ real life pattern? [3.] Can residents manage energy efficiently by knowing their own life pattern? [Copyright &y& Elsevier]

The paper refers onto the experimental investigation of the precise flat angle positioning drive. After a deeper investigation of the used microstepping controller, the authors depicted the causes of the observed rotation nonlinearity. A special test bench with a precise rotation encoder has been produced for the purpose, besides that the angular positions of the formed microsteps have been measured with a fast, slow and mixed current decay mode set. After the analysis of the obtained results, the source of nonlinearity has been determined, and then the possible solutions have been defined and tested. The paper presents the guidelines for a new controller design, based on the current research study. [ABSTRACT FROM AUTHOR]

Intensification of natural thermal convection near electric devices is possible by application of additional elements as screens creating convection canals close to the device. In the earlier authors paper the results of the analysis of thermal convection with the use of only one additional screen close to the electric device were presented. This paper presents computer modelling of thermal convection when two screens near the electric device are implemented. One of the screen is a wall close to the electric device. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the laws and regulations that affect the practice of energy medicine. State law often has more impact on a health care practice than federal law, but federal law provides a common denominator among states. Device law is emphasized here because practitioners of energy medicine are more likely to use devices than drugs. For purposes of this paper, energy medicine is defined as practices that measure or benefit energy flow and overall energy in the body. This broad definition encompasses things as diverse as certain forms of exercise, measurement of meridian resistance, the use of electrical current or magnetic pulses to relieve pain, and the use of light, sound, scent, touch, position, or movement to stimulate the body''s own electrical systems. What is of greatest importance in determining legal implications of a practice is whether there are any health-related claims. Two federal entities are pivotal. The Food and Drug Administration (“FDA”) is authorized to protect health and safety and the Federal Trade Commission (“FTC”) is authorized to protect consumers from false or misleading advertising. There are 5 things that FDA looks at: 1) intended use, 2) claims made in advertising and in labeling, 3) substantial equivalence to a predicate, 4) safety, and 5) effectiveness. A concern regarding any one of these can be the basis for denying clearance to market a device. The FTC looks at whether statements are true and substantiated and whether they might be misleading. The FTC often consults with the FDA on the interpretation of technical information. [Copyright &y& Elsevier]

Abstract: Solar PV systems have evolved from small stand-alone applications through residential and commercial systems to MW-scale installations and groups of systems that feed significant energy into the utility grid. High PV penetration levels create a number of challenges for the management of the operation of the utility grid. This paper will cover the current and historic status of the integration of renewable energies into utility grids over a variety of global regions. This includes grid control and network planning. The technology for the integration of PV is described including the codes and standards governing the utility interactivity requirements. This will include short term dynamic responses as well as power ramp rates. Geographic, technological, and meteorological factors will be discussed. The coordination of meteorology and energy production is a key factor that is examined in detail including real world data. The paper includes a discussion of future utility grid features to support increasing levels of PV and other renewable generation sources. [Copyright &y& Elsevier]

Abstract: The Self Excited Induction Generator (SEIG) is an isolated power source whose terminal voltage and frequency are controlled by the excitation of the capacitance or the load impedance. This paper presents a method for calculating the minimum excitation capacitance using the equivalent circuit approach for analyzing the steady state operation of SEIG. A new strategy based on an active power filter (APF) for controlling the current and power quality of the self excited induction generator (SEIG) is also presented in this paper. The shunt active power filter was implemented using a three phase PWM current controlled voltage source inverter (VSI) and connected to the wind generator and loads in order to compensate the current harmonics and reactive power. The PWM-VSI gate control signals are derived from hysteresis band current controller. The proposed active filter proved to play an important role and give good dynamic response and robust behavior upon changes in load parameters. This investigation demonstrated that power average control strategy can facilitate the improvement of the power quality. The proposed control method extracts fundamental (reference) components of the source current for the shunt active power line conditioners for nonlinear and unbalanced loads. The Power average approach additionally maintains the voltage of the capacitor (of the PWM inverter) nearly constant without any external control circuit. The shunt APF in conjunction with the proposed controller performs perfectly under different steady state and transient conditions. The simulation results with nonlinear loads and unbalanced loads have showed the effectiveness of the proposed scheme for harmonic reduction in Wind based Power Generation. [Copyright &y& Elsevier]

Abstract: The probability of single phase grounding is very high among the faults in distribution network of our country, according to statistics it has reaching at 80 percents. Therefore, the fault selecting line of low current grounding system becomes a thorny problem, it is very often that we can’t accurately locate the fault happening time, thus couldn’t choose effective information of fault happening time. This paper puts forward the method which uses the advantage that signal singularity detection of wavelet transform of presicing timing for single phase grounding in distribution network, to pick-up detailed transient information when single phase grounding fault happening in distribution network, then the relay protection device takes action timely and accurately. Because the current signal is smaller when low current grounding happens in distribution network,it is very easier to be interfered by other devices outside, so , time orientation by singularity of zero sequence voltage signal at the fault happening time is adopted in this paper. [Copyright &y& Elsevier]

The paper presents solution for wireless and battery-less measurement in the enclosed areas. The principle is based on passive RFID; nevertheless this' paper is focused on high power-demanding applications such as MEMS accelerometers, gas sensors, piezoresistive strain gauges, etc. Standard RFID communication scheme (sensing the input current change on the primary side) cannot be used in this case, because the communication channel is overloaded by the high power load. Paper presents possible solution which is based on the dual frequency scheme -- one frequency for powering and other .for the communication. This is ensuring capability for measurement up to several centimeters in the frequency bands 125 kHz and 375 kHz. It can be suitable for continual measurement in isolated systems such as the rotating objects, concrete walls, enclosed plastic barrels, high temperature chambers etc. [ABSTRACT FROM AUTHOR]

A grounded parallel lossy active inductor and two current-mode (CM) universal filters are presented in this paper. All the circuits use two voltage followers (VFs) and a current follower (CF). The parallel lossy active inductor includes a grounded capacitor which is attractive in integrated circuit (IC) technology. The CM universal filters have one input and standard three outputs such as band-pass (BP), low-pass (LP) and high-pass (HP) responses. All-pass and notch outputs can be obtained by adding extra one CF. Suggested structures in this paper can be constructed with commercially available active devices such as AD844s. Non-ideal gain and intrinsic X-terminal parasitic resistor effects are examined. Several computer simulations with SPICE program and experimental results by employing AD844s are drawn to verify theoretical ones [ABSTRACT FROM AUTHOR]

This paper presents fifteen distinct practical realizations for dual-X second generation current conveyor (DXCCII) using commercially available integrated circuits. Detailed comparisons and results are presented to verify the utility of proposed realizations. The catalog of proposed realizations is a first attempt and is expected to be useful for testing newly developed circuits based on dual-X second generation current conveyor. Each of the first fourteen proposed realizations uses four ICs. One three IC based implementation is further given making the total count fifteen. Some additional features are also explored which further enhance the versatility of DXCCII. The paper further presents a novel and compact quadrature oscillator to verify the applicability of the proposed realizations. Single resistance control of the frequency of oscillation is also demonstrated by employing the new gain-variable DXCCII. Experimental results are also included along with simulation results to validate the proposed theory and its practical significance. [ABSTRACT FROM AUTHOR]

This paper is in continuation with the very recent work of Prasad et al. [14], wherein new realizations of grounded and floating positive inductor simulator using current differencing transconductance amplifier (CDTA) are reported. The focus of the paper is to provide alternate realizations of lossless, both positive and negative inductor simulators (PIS and NIS) in grounded form using z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), which can be considered as a derivative of CDTA, wherein the current differencing unit (CDU) is reduced to a current-controlled current inverting unit. We demonstrate that only a single ZC-CCCITA and one grounded capacitor are sufficient to realize grounded lossless PIS or NIS. The proposed circuits are resistorless whose parameters can be controlled through the bias currents. The workability of the proposed PIS is validated by SPICE simulations on three RLC prototypes. [ABSTRACT FROM AUTHOR]

This paper will analyze the spectral structure of the instantaneous active current. Multi-phase systems voltages and currents are discussed. Examples are taken for two-phase system and three-phase systems. In order to obtain experimental examples, numerical processings are carried out. The paper presents an instantaneous active current spectrum for different regimes of the three-system phase. [ABSTRACT FROM AUTHOR]

Results of the investigation of a double layer dielectric system consisting of textile and rigid dielectric layers is discussed in this paper. It is shown that the double-layer system submitted to an external stress produces an electrical potential distribution due to the trybo-charge generated during contact between the rough surface of an elastic-textile and the rigid dielectric layers. It is shown that the local effective surface charge density on the rigid dielectric layer depends on the intensity of the local stress - local pressure value. The charge generated produces proportional voltage on the solid dielectric layer after removing the elastic (textile) one. This way the pressure may be converted into a voltage signal, which is „memorised“ by the solid dielectric layer. The "pressure map" converted into an „electric potential map“ can be visualised by potential distribution determination. Potential distributions obtained for systems made of different materials (textiles) are presented in the paper. [ABSTRACT FROM AUTHOR]

The magnetization component of input current of low-rating three-phase induction motor is large which results in poor power factor particularly at low-load conditions. The situation becomes critical when motor is fed from a distributed generating (DG) system. In this paper, the performance analysis of induction motor is carried out for minimum input VA. A distinct novel slip is found at which the input VA is minimum independent of the load conditions. This optimum slip is expressed in terms of motor per-phase equivalent circuit parameters. This novel relationship is valid for every induction motor. As compared to rated conditions, a drastic reduction in VA with a large improvement in power factor is observed. Although, a marginal change in output power and efficiency is recorded. All the analytical, simulated and experimental results match each other with a very fair degree of accuracy. [ABSTRACT FROM AUTHOR]

This paper presents the behavior of electrical arc in automated fuses. There are electrical devices frequently used nowadays, having an essential role in protecting electrical component. Because of weakened electrical contacts in the exit or entry area of the electrical current, the phenomenon of electrical arc appears, in the interior of the contacts, which stresses the material after a certain time period. Once thephenomen of material punching has started, the electrochemical corrosion appears, playing a role in damaging the properties, respectively the quality of the material. In order to observe the effect of the electrical arc, a Comsol model has been created for electrical contacts which are shifted from 1µm to 30 1µm. These contacts have been subjected to variable voltages from 1V to 450V. The results obtained through simulation can be used to combat the electrical corrosion in electrical instalaltions. [ABSTRACT FROM AUTHOR]

In this paper will be presented a possibility for realization of numerical protection system, for a transformer. In fact, this system is realized from any modules: a module for measured of current, a module for measured of tension, a data acquisition and processing system realized with microcontroller and communication module [ABSTRACT FROM AUTHOR]

The issue of industrial heritage conservation as well as its new use has been worldwide hot topic for a longer period. Industrial heritage provides one of the most important records of urban development and progress of human civilization in the last two centuries. Monumental industrial buildings reflect the extraordinary technical and economic development and the progress in science and technology. Even after the termination of their original function, industrial heritage buildings and equipment's with their architecture are still participating in the atmosphere of each city in a significant way. The electricity industry played a key role in the life of the mankind. Electricity and electrical currents are intangible symbols of the creative use of the natural forces by man, also a real driving force for technological progress and extensive development of human knowledge. The young generation takes it for granted, with no interest in learning about its causal impact and context. A global problem is the decreasing interest of young people in studying natural sciences and engineering, which is a prerequisite for further technological progress and socio-economic development of the life of inhabitants. This lack of interest is justified by the high abstraction and lack of clarity in the scientific and technical fields which are move about from people's everyday lives. Therefore, the current trend is developing an interactive virtual model of presentations of this rich source of knowledge and experiences. Those are able to make technical museums more attractive and allow the inspirational use for a broader audience. The article “Interdisciplinary cooperation in the virtual presentation of industrial heritage development” is aimed to explore opportunities for collaboration between theoretical research, monument preservation, virtual reality and architectural practice. It deals with the identified key factors that conditionally affect the quality and efficiency of architectural design process within the cooperation in the conservation process. As well as it deals with the opportunities of transfer the research results from futuristic disciplines. For this purpose, the paper examines the case study “the reconstruction of old Power plant in city Piestany” and describes one of the possible solutions on the basis of the operational research model so-called “Educational polygon.” [ABSTRACT FROM AUTHOR]

This paper aims at modelling an electronically coupled distributed energy resource with an adaptive protection scheme. The electronically coupled distributed energy resource is a microgrid framework formed by coupling the renewable energy source electronically. Further, the proposed adaptive protection scheme provides a suitable protection to the microgrid for various fault conditions irrespective of the operating mode of the microgrid: namely, grid connected mode and islanded mode. The outstanding aspect of the developed adaptive protection scheme is that it monitors the microgrid and instantly updates relay fault current according to the variations that occur in the system. The proposed adaptive protection scheme also employs auto reclosures, through which the proposed adaptive protection scheme recovers faster from the fault and thereby increases the consistency of the microgrid. The effectiveness of the proposed adaptive protection is studied through the time domain simulations carried out in the PSCAD ⧹ EMTDC software environment. [ABSTRACT FROM AUTHOR]

The electrical resistivity is an important parameter describing materials’ ability to conduct electric current. Dry cementitious materials exhibit very high value of the electrical resistivity due to their insulating nature. Indeed, the electrical resistivity of an oven-dried concrete is about 10 9 Ω m. However, it can be significantly decreased by a sufficient amount of electrically conductive admixture. Such an enhancement is beneficial in self-sensing or self-heating concrete design, but it is not convenient in special cases such as design of concrete used for railroad ties production. In this case, mechanical properties (tensile strength) need to be improved without an accompanying decrease of the electrical resistivity. In this paper, reference concrete together with three types of steel-fibre reinforced concrete (0.5% vol., 1% vol., 2% vol.) were prepared and analyzed in terms of determination of electric properties. Experiments were carried out in both, DC and AC electric regime by means of precise DC multimeter and LCR meter measurements. [ABSTRACT FROM AUTHOR]

This paper highlights the electric energy harvesting system that consists of piezoelectric (PZT) stack transducer which is excited by random mechanical oscillating force and charges the Li-Ion battery. This battery is a power supply for LED lamp lighting. A very big electric capacitance of the multilayered PZT stack affects on the electric energy flow from PZT energy source to the electric sink. The reason for this influence is because the electric capacitance of the device, its mechanical losses and leakage increase along with the increased number of PZT layers. An electronic circuitry of the studied energy harvesting system provides the interfaces between the piezoelectric device and electric load. Such the circuits should match the input impedance of electric load (battery) and output impedance of voltage source (PZT stack). Basing on the experimental data and the finite element (FE) investigation we derive and tune the lumped model of multilayered PZT stack, which transforms the energy of low frequency mechanical excitation with random amplitudes and discretely distributed frequencies to the energy of electric current. In order to optimize an efficiency of harvester we find the number of PZT layers at constrained excitation parameters, stack's dimensions, and generated voltage required by the charging battery. The lumped model of the whole harvesting system has been built in SimElectronics / Simulink MATLAB© environment. It was also simulated to find the best harvesting system parameters. [ABSTRACT FROM AUTHOR]

Antenna parameters particularly relevant to electrically small antenna design are reviewed in this paper. Source current definitions are accentuated leading to the introduction of the source concept which advantageously utilize only spatially bounded quantities. The framework of the source concept incorporates powerful techniques such as structural and modal decomposition, operator's inversion and current optimization, thus opening new, challenging possibilities for antenna design, analysis and synthesis. [ABSTRACT FROM AUTHOR]

The effect of self-producing heat and external radiation on the insulating property of wire are studied experimentally in this paper. In the experiments of self-producing heat of wire, 6 types of wires are used under the situation of overloading. The results show that the effect of the temperature rise of wire on insulating property of wire is remarkable. Under the situation of having electric current wired to produce heat by itself, the insulation resistance of wire decreases and the leakage of electricity electric current enhances. Under the situation that electric current is relatively stable, the temperature becomes stable when rising to a certain value, conducting wire heat dissipating and fever heat are in an equilibrium state. In the experiments of external radiation, such as the situation of building fire, RV sheathed wires present a similar regulation to the self-producing heat experiments. The difference is that the effect of external factor (such as air flow, voltaic instability, etc.) on temperature of wire is more obvious than that on the insulation resistance of wire. When external factor makes the wire temperature decrease to a certain value, the insulation resistance value is higher than that out of the effect. [ABSTRACT FROM AUTHOR]

In order to check the overloaded wire's ignition capability to the wool fabric, different multiples overloaded current were selected as the main parameter, and meanwhile, the thickness of the wool fabric and the contact way were considered as well in this study. Moreover, the temperature's rising law and the ignition of the wool fabric under different ignition conditions were obtained. The result showed that the thicker the wool fabric, the more susceptible to be ignited. It also has been found that it takes shorter time to be ignited when the overloaded current is greater and the contact way is wrapping. The conclusion of this paper would provide guidance for investigation on fires related with overloaded wire and the wool fabric. [ABSTRACT FROM AUTHOR]

The paper aims to conduct a case study on the influence of the supply voltage variation on the parameters of electric power cables of low voltage consumers . The argument which was the basis for the study, was the fact that the voltage variation is a parameter of quality of electricity supplied by the network operator and respecting the limits of its variation is regulated both by performance standards , and by the electricity supply contract between electricity suppliers and consumers, consumption per seat basis. [ABSTRACT FROM AUTHOR]

A computer model of a synchronized asynchronous motor has been designed and divided into blocks. The computer model consists of units calculating magnetizing currents, stator and rotor current, the main electromagnetic flux and EMF of windings, electromagnetic torque of the rotor, the angular velocity, and the angle of the motor shaft rotation. The paper presents the results of the synchronization process transients as well as the dependences of the motor torque on the synchronization phase. [ABSTRACT FROM AUTHOR]

A novel full on-chip low dropout linear regulator is presented in this paper. This LDO is designed with single ended OTA for better gain which in order improves load regulation. A self-biased comparator is used to detect the change in regulated voltage and increase slew rate at output of error amplifier. A frequency compensation scheme is used which maintains LDO stable over entire load current range i.e. 0-100 mA. The load regulation of the LDO is 0.68 μv/mA. The overshoot/ undershoots in the output voltage under the extreme load transients are 120 mV/165 mV respectively. The settling time is only 750nS. The LDO presented requires a bias current of 50 μA and 200 mV dropout voltage and is designed with UMC 130mmrf technology. The LDO presented is useful analog application such as baseband of receiver where high load regulation is necessary for robust application. [ABSTRACT FROM AUTHOR]

This paper gives an introduction to the single-phase instantaneous PQ (P-instantaneous real power and Q-instantaneous virtual power) theory and carries out the calculation and simulation analysis on reactive power, active power, instantaneous reactive power and instantaneous active power for the single system before and after the compensation of the multilevel inverter. By analyzing the experimental results, it can be seen that harmonic current of the single phase system decreased significantly after using multilevel inverter, while the power factor improved obviously. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to develop a possible variant of an analogical modelling and a numerical simulation for a single-phase resolver pursuing a more unified and systematized approach. By knowing the input voltage, the proposed simulated model calculates the output voltage, the input/output current at any time (sequence), in any position of the single-phase resolver rotor, in dynamic or static mode of operation. The LabVIEW virtual instrument can display the rotor position any time, too. [ABSTRACT FROM AUTHOR]

This paper aimed to monitor the different bus parameters in a substation from a centralized control room with the help of Zigbee enabled wireless sensor network (WSN). The parameters such as magnitude and phase angles of voltage and current, frequency, rate-of-change-of-frequency (ROCOF), active and reactive powers are measured using a state-of-the-art customized Zigbee enabled phasor measurement unit (ZPMU). The data from different ZPMUs at different bus nodes are acquired with the help of WSN system in order to have a centralized monitoring of different equipments load status. The coordination among different parameters for different buses and/or equipment is done from a centralized control room within the substation or plant with the help of substation management software and Zigbee networking. The data thus collected are utilized to study the power flow status of the different buses on real time basis and are stored within a server based database for future analysis purposes. [ABSTRACT FROM AUTHOR]

In the present paper, a parametric electromagnetic model is developed for the switched reluctance generator (SRG) with the finite element method (FEM) using the ANSYS finite element (FE) package which can be considered appropriately for accurate analysis and optimal design of the SRG. The performance principles of the SRG are briefly explained and some important electromagnetic characteristics of the SRG including phase current and instantaneous input power are predicted using the developed electromagnetic model. Carrying out the transient analysis, there is this possibility to predict the flux waveforms within the machine and therefore a core loss model is then introduced for the SRG. Applying the developed electromagnetic model to an 8/6 SRG, simulation results are presented and some critical issues are identified which can be attended in design of the control system of the SRGs. [ABSTRACT FROM AUTHOR]

In this paper some interesting and novel features of a four-terminal (4T) network are presented. A single DC current source (J) is switched over and connected in turns to opposite arms of the four-element bridge circuit. This two-output circuit with two voltage outputs is called a double current circuit (2x1J). The output voltages are differently dependent on the arm resistance increments and their values are given in absolute and relative units. An original application with two sensors acting as strain gauges and RTD's is presented. Signal conditioning formulas of 2D measurement of deflection and temperature of a cantilever beam are discussed in detail. Some results achieved with the use of the circuit are presented, as well. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyze the temporal component of the electric field and the activation function, during magnetic stimulation technique. The spatial distribution of the induced electric field for a "multilayer" coil is calculated by superposition the electric field caused by each part of the coil's winding. The temporal component of the electric field can be separated from the spatial component and may be calculated separately. Assuming that the tissue is purely resistive, this approximation is correct at the operating frequency (f = 2500 (Hz)) of magnetic stimulation. The computation of the temporal distribution of the electric field induced in the tissue during magnetic stimulation and its axial derivative along the nerve fiber (activation function) are performed in transient analysis of the circuit source. [ABSTRACT FROM AUTHOR]

The wear of a cutting tool determines its life. Lesser the wear, more is the life of cutting tool and consequently the tool has to be replaced less frequently. This results in an increase in productivity of the machining operation, reduces manufacturing lead time and lowers the cost of production. Optimization of the process, use of cutting fluids for lubrication and hard coatings on the tool are the widely used methods to reduce tool wear. It has been recorded in previous studies that application of electric current to moving surfaces in contact, influences the wear of both the surfaces. The wear rate of the anodic surface was reduced and that of cathodic surface was increased. This paper attempts to study the effects of application of DC electric current on wear of turning insert during the turning operation of stainless steel 304 material. In the first phase of study, an L 18 orthogonal array experiment was designed to study the effects of various factors (use of cutting fluid, polarity of cutting tool, applied voltage, cutting speed, feed and depth of cut) on insert wear and surface roughness of stainless steel 304 rod post machining. In the second phase of the experiment, the insert wear at different polarities were recorded at regular intervals of 70 mm cutting length while keeping the cutting parameters constant. Each cut was carried out for a total of 560 mm. The recorded readings are compared. [ABSTRACT FROM AUTHOR]

The fundamental issue in the area of remote handling and robotics is the reliability of power electronics system. Detailed analysis and simulation studies are very much relevant as the prebuilt drive solutions are costly and performance of drive system depends upon the reliability of control algorithms incorporated in the drive. The modulation techniques also play an important role in the dc voltage utilization. This paper presents a comparative simulation study for the analysis of complete BLAC drive using PI controller using two types of modulation techniques namely Sinusoidal Pulse Width (SPWM) and Space Vector Modulation (SVPWM). [ABSTRACT FROM AUTHOR]

In order to solve the fire detection problem of the electrical fault arc in series, it is introduced in this paper to decompose and reconstruct current waveforms of the fault arc in series, based on MALLAT arithmetic of the wavelet transform, which were obtained by the experimental device of the electrical fault arc in different resistance loads and different frequencies. By introducing the wavelet transform method in the data analysis, current waveforms of the fault arc in series are processed with intercalating the wavelet parameter, and the characteristic parameter and frequency range of the fault arc current signal can be distilled. And then, the special frequency range of the fault arc current signal in series, based on different electric loads and different frequencies, can be regarded as the judgment of the fire detecting alarm, which could provide the technical base with the efficient detection method of the electric fault arc in series. [ABSTRACT FROM AUTHOR]