Abstract This paper presents a numerical study of heat transfer inside the adsorber-collector of a solar adsorption refrigerator using the activated carbon AC35-methanol pair. The objective is to estimate the amount of the heat loss through the adsorber-collector, during the solar heating phase, and to determine the effect of heating time on the thermal efficiency of the system. The numeric…
Abstract Background: The Saint-Venant problem for porous elastic cylinders is of interest both from the technical and mathematical point of view. The intended applications of solution are to mechanics of bone and to some engineering structures. Method: This work investigates the Saint-Venant problem for almost prismatic bars made of an isotropic porous material. We express the solution in …
Abstract Background: Strain and stress conditions in sheet metal shearing are of interest for calibration of various fracture criteria. Most fracture criteria are governed by effective strain and stress triaxiality. Methods: This work is an attempt to extend previous measurements of strain fields in shearing of steel sheets with the stress state calculated from the measured displacement fie…
Abstract Background: Impedance pump is a simple valveless pumping mechanism, which transports fluid through the mismatch of impedance in the system. Mismatch in impedance occurs when an asymmetrical periodic excitation is exerted on the elastic tube. Periodic asymmetrical excitation will then produce a unidirectional flow. Considering a multi-stage system with a single and constant power so…
Abstract In this study, bidirectional dc–dc (BDC) converterbased dynamic voltage restorer (DVR) is proposed for compensation of severe voltage sag/swell problems in a medium voltage system. Among these problems, voltage swells provoke the voltage rise at dc-link capacitor of DVR. This undesirable situation may explode the dc-link capacitors and switches, and cause high-power losses. In DVR …
Abstract The aim of this work is the synthesis of a type-2 fuzzy logic PID controller for DC–DC boost converters. Performances of the proposed controller are evaluated and compared with those of type-1 fuzzy logic PID controller using the same structure and under similar operating conditions. Simulation results showed that the type-2 fuzzy logic PID controller has better performances than t…
Abstract In this paper, the modal series method is revisited and an extension on the method to include higher order terms is proposed. This proposal is based on the introduction of the multidimensional Laplace transform and association of variables theorems to deduce the analytical closed-form solution when it is applied to the analysis of a nonlinear power system model. The method is systema…
Abstract The time synchronous averaging (TSA) is a wellknown technique used for early detection of bearing failure in electrical machines. This method is very efficient if the characteristic default frequency is perfectly known. In this article, a reduced frequency model, derived from ESPRIT algorithm, is used to provide a very accurate estimation of the fault frequency. The precision obtaine…
Abstract This paper proposes a simplified finite-controlset model predictive current control (FCS-MPCC) without mechanical sensors for permanent-magnet synchronous generators (PMSGs) in variable-speed wind energy conversion systems. The procedure of selecting the best switching vector is optimized by computing the reference voltage vector (VV) directly from the reference current. Subsequently…
Abstract this paper presents a sensorless control approach of inverter dc-bus voltage using extended Kalman Filter (EKF). A positive sequence detection of grid voltage and load current is also proposed. The dc-bus voltage estimated by EKF is combined with the modified instantaneous power (p–q) control technique for photovoltaic system application to improve electrical energy quality at the …
Abstract The harsh operating environments of many electronic systems, such as in the automotive and aerospace applications, make the semi-permanent connector terminal susceptible to intermittent failure or high contact resistance. Fretting, small cyclic movements at the contact interface, is exacerbated by oxidation to cause fretting corrosion, resulting in these types of failures. However, d…
Abstract This paper characterizes the error in distance relay operation due to the existence of asynchronous frequency components when a fault in a line with series compensation occurs. The distance relay model and the impact of nonfiltered frequency components using the conventional digital filters is presented, an errorwill appear in voltage and current fundamental frequency phasors estimat…
Abstract This paper develops a precise proportional–integral (PI) type control system for repeatable tracking control of a permanent magnet synchronous motor (PMSM) under motor parameter and load torque variations. By adding a very simple learning feedforward term, a conventional PI control system can be enforced to have a perfect tracking performance under model parameter and load torque v…
Abstract This paper investigates the operation of a DC microgrid which is connected to a DC distribution network using a modular-isolated bidirectional DC–DC converter. The bidirectional power flowcapability of the proposed modular converter provides the possibility of power exchange between DC microgrid, and DC distribution network contains some microgids. The extendable configuration of t…
Abstract Power transformer protective relay should block the tripping during magnetizing inrush and rapidly should operate the tripping during internal faults. There are a variety of protective relays using different measuring techniques to provide reliable and secure transformer protection. These types of the protective relays include electro-mechanical, solid state, digital and numerical re…
Abstract This paper presents genetic algorithm optimization method with a suitable objective function to determine optimum location and rated values of FACTS devices by taking into account changes in the power system load over time. In this study, annual daily load profile is considered as a whole instead of an instant load profile while looking for optimum size and location of FACTS devices.…
Abstract This paper proposes a new multi-objective dayahead market clearing (DAMC) mechanism with demand response offers, considering realistic voltage-dependent load modeling. This paper presents several objectives such as Social Welfare Maximization including demand response offers (SWM), Load reduction Minimization (PredM), and Load Served Error (LSE) minimization. Energy and demandside r…
Abstract Optimal reactive-power dispatch (ORPD) is one of the most difficult optimization problems regarding to power-system operation which is heavily related to system stability. To overcome ORPD problem, in general, the total real-power loss is reduced by determining the power-system control parameters, such as generator voltages, tap ratios of tap-changer transformers, and compensated rea…
Abstract Single-tuned passive filters offer reasonable mitigation for harmonic distortion at a specific harmonic frequency with a high filtering percentage, but resonance hazards exist. Traditional damped filters offer high-pass filtering for the high-frequency range, but suffer from extra ohmic losses. C-type filters may operate in a manner similar to the tuned filters with lowdamping losses…
Abstract The paper suggests a new procedure for the estimation of the parameters (amplitude and phase) for a complex periodic signal, based on the concept of analytic signal (AS). Starting from the supposition that the signal fundamental frequency has been estimated in advance at an independent stage, new analytical relations are derived for fast calculation of the unknown parameters, entail…
Abstract The paper deals with the influence of a loss of one phase of a feeding source on the properties of a five-phase induction machine. The attention is paid to the waveforms of the currents in individual stator phases, the increase in torque pulsations and the decrease of speed in emergency operation after the disconnection of a faulty phase of the source. Machines in star, pentagon and …
Abstract The efficiency and installation costs of solarpowered drip irrigation systems depend on not only the efficiencies of the electrical motor, its driver, and the pump, but also the efficient usage of irrigation water. In this study, the initial installation costs and energy consumption of photovoltaic irrigation systems were decreased by obtaining the soil moisture level as a reference …
Abstract The application of the XLPE cable under DC stress is now being considered as one of the promising tool for enlarging the limited transmission capacity of the traditional electric power cable due to the several technical advantages. Therefore, many research institutes are trying to improve the performance by carrying out experimental investigations related to the reliability of the ca…
Abstract The formulations employed to the optimization of passive filters can be classified as formulations of a single objective or formulations with multiple objectives. The single-objective formulations normally are devoted to determine the filters of lowest cost that assure the compliance with the power quality standards, while in the multi-objective approaches are added other goals that …
Abstract It has been conventionally believed that there exist 4n variables P, Q, V, θ for an n-bus system in the power flow computation, while we have 2n power flow equations. In this article, the authors argue that the number of variables in an nbus system is not 4n but 4n−1, hence the power flowsolution can be obtained without specifying the reference angle of the slack bus.We then deliv…
Abstract The effect of high photovoltaic (PV) penetration with constant injected voltage on the loss of excitation phenomenon of single machine infinite bus power system with two transmission lines has been investigated. The PV modules are integrated to the power system at the same bus of the synchronous generator via DC–DC buck–boost switch mode converter, three-phase DC–AC switch mode…
Abstract This article deals with the problem of electrical discharge initiation in mineral oil in the setup of insulated electrodes. The results of laboratory experimental studies were collated with the results of the numerical calculations of electrical field stress. Both kinds of the research methods were applied to analyze the two model electrode setups immersed in mineral oil: setup with …
Abstract In the October 2009 issue of this Journal, we introduced a special pot type, which could improve the energy efficiency of induction cooking, make the boiling process faster and the cooking more comfortable. The dissipated power in the new pot was significantly higher than in the traditional ones at any inductor current. In this paper we show another pot type with similar advantages, …
Abstract Today electronic devices require a power supply without any variation or disturbance. Nevertheless, electrical variations presented in power lines are more frequent and powerful. The consequences of poor power quality devices. Thus, in this study, an FMEA is presented to know which electrical variation has more effect on the reliability of electronic devices. The analysis was perform…
Abstract The results of the breakdown time lags obtained by commercial “OSRAM St 111” gas diode are presented. The memory curves for different voltages (for 220, 250 and 300 V) are shown. The analysis of the experimentally obtained distributions (histograms and Laue distributions) for different voltages (for 220, 250 and 300 V) and different relaxation times (from 1 to 1500 ms), as well a…
Environmental Fluid Mechanics (EFM) is the study of motions and transport processes in earth’s hydrosphere and atmosphere on a local or regional scale (up to 100 km). At larger scales, the Coriolis force due to earth’s rotation must be considered, and this is the topic of Geophysical Fluid Dynamics. Sticking purely to EFM in this book, we will be concerned with the interaction of flow, …
Abstract Every day, the evaluation of classical distribution networks (DNs) to smart grids (SGs) has become a necessity, and renewable energy sources (RESs) are an important part for smart grids. One of the most significant problems for RESs is the sustainability of energy, because the raw material storage is not possible for renewable energy sources as photovoltaic (PV), wind, etc. Therefore…
Abstract Line start-permanent magnet synchronous motor (LS-PMSM) is one of the modern high efficiency motor introduced to the industry, recently. Like other types of electrical machines, various failures may happen in LS-PMSM during its life time. Among different failures which may occur in the motors with squirrel cage rotor, rotor fault (broken rotor bar) is the most significant one. This p…
Abstract This study presents an advanced computer interactive system for automatic parallel connection of synchronous generators and load sharing control between them. Because of its high operation speed and precision, a dsPIC microcontroller has been used in the study to control the conditions for paralleling and then to realize the connection, to transfer the real time data among the contro…
Abstract The paper introduces the possibility to eliminate certain groups of spatial harmonics of the current layer, magnetic flux density in the air gap and flux in the yoke of the induction machine with the aim to increase the efficiency. The content of higher spatial harmonics is reduced by means of the so-called combined winding. It is shownhowthis winding must be arranged in stator slots…
Abstract Traditionally, the core losses of permanent magnet synchronous motors are assumed to vary as a function of rotational speed and the supply voltage. In this paper, the effect of armature reaction on the core losses under constant speed and stator voltage is studied. The load angle of the machine is varied, and the core losses are determined using the finite element analysis.To explain…
Abstract This paper presents an experimental investigation of a small-scale wind turbine conversion system (WTCS), using wind power simulator based on a permanent magnet type synchronous generator (PMSG) which is directly coupled to a servomotor to emulate the WTCS. The wind power simulator is either speed or torque controlled in which propose a “wind shaft”, to verify the dynamic and sta…
Abstract In this paper, an extrinsic Fabry–Perot interferometer (EFPI) has been demonstrated for strain measurements. A monochromatic light source with a wavelength of 1310 nm is propagated into a single-mode fiber and then passed through the sensing arm. Approximately, 4 % of the beam is reflected off at the fiber end generating the “reference signal”, while the rest is next transmitte…
Abstract A squirrel cage induction motor has been the workhorse in industry for variable speed applications in a wide power range that covers from fractional horsepower to multi megawatts. But the control and estimation of ac drives in general are considerably more complex than those of dc drives. The advent of vector control techniques has partially solved induction motor control problems. H…
Abstract Magnetic devices are essential components in the field of power electronics. Exploiting the non-linear behavior of inductors and transformers offers the great merit of increasing the performance of switch mode power supplies. For instance, the light-load efficiency of a buck voltage regulator can be improved by using a non-linear inductor with stepped air gap. Moreover, non-linear ch…
Abstract This study presents an artificial neural-network (ANN)-based digital fault classification and location algorithm for medium voltage (MV) overhead power distribution lines with load taps and embedded remote-end source. The algorithm utilizes frequency spectra of voltage and current samples which are recorded by the digital relay at the substation. In the algorithm, to extract useful i…
Abstract Distributed generation (DG) is predicted to play an increasingly important role in the future power system. DGs, however, can provoke technical problems when they are added to the existing system. An islanding is one of those problems while using DGs. During that mode, the power electronic interface of DGs has both roles of keeping the point of common coupling’s voltage within a re…
Abstract In this paper, a novel single-stage single-phase buck–boost inverter design is presented. Depending on the duty ratio, the output voltage of the proposed inverter can be lower or higher than the DC input one. Similar to the conventional voltage source inverter, the proposed inverter includes four power electronic switches without the need for any extra switches. All the inverter fo…
Abstract Validation of an estimated model is not a trivial task because it depends on the purpose of the model, which usually defines the most important features of the model. Thus, in a validation process, the use of diverse tools that exploit different domains is recommended. Here, with this aim, a scale for model validation is proposed that combines the Normalized Root Mean Square Error …
The transport properties of concrete measure the ability of fl uids to move through it. The equations for them were fi rst documented by the end of the nineteeth century (Fick 1855 ; Darcy, 1856 ) and applied to concrete by the middle of the twentieth century (Powers et al ., 1954 ). However, they remain diffi cult to measure, particularly if the common in situ tests are used. Interest in …
The infrastructure of constructed facilities for the transportation and housing of people, goods, and services, which grew exponentially over the latter half of the last century is rapidly approaching a critical period, with increasing signs of deterioration and reduced functionality. Defi ciencies in the existing bridge inventory, for example, range from those related to wear, environment…
Settlement calculation is one of the three major issues in foundation engineering and it has not yet been resolved completely. Especially settlement calculation of super high-rise buildings still remains the most difficult problem for engineers. Due to lack of practical settlement data, there is few systematic research result and rarer monograph to investigate this special problem. This bo…
The provision of earthquake resistant structures and facilities is one ofthe main concerns of Civil and Earthquake Engineering Profession. As such, the main objective of seismic instrumentation program for civil engineering structural systems is to improve our understanding of the behavior and potential for damage of structures under the dynamic loads of earthquakes. As a result of this und…
In the present decade, the world has witnessed many great earthquakes like Bhujj in India in 2001, Iran in 2003, the Asian Tsunami in Indonesia in 2004 and Pakistan in 2005 resulting in the death of thousands of people and significant property damage. Housing and safety are basic human needs. Structures adequately designed for usual loads need not necessarily be safe for earthquake forces.…
Our book is intended to serve as both a textbook for graduate level courses in enfineering and reference volume for engineers and scientist. We assume that the reader has the background of the B.S. level mechanics courses in departements of civil, mevhanical, or aerospace engineering. Aside from synthesizing the main results already available in the literature, our book also contains some new r…