Search

This paper proposes a new method to improve re performance of intra-field interpolation which is the mos~ important element of deinterlacing method. Traditional edge- based methods were poor at determining accurate edge iirection which decides interpolation performance. The 7roposed method decides the direction and slope of edge based on locally adaptive-thresholded binary image to mprove efficiency and accuracy, and it also increased the ~orizontal size of search window to 15 for better direction ietermination at gentle slope. Compared to traditional edge- based methods, interpolation based on binary image, which is ,`enerated using the proposed method, leads to great erformance improvement. With computer simulations for a ~`ariety of images, this paper shows the new approach is much ~etter than traditional methods.. [ABSTRACT FROM AUTHOR]

This paper presents an implementation of an ~daptive beamformer in a hands-free unit. The proposec~ ~daptive beamformer suppresses stationary noise an~ nterference sound. The adaptive beamformer and acoustic `cho canceller were implemented in a compact hands-free mit with a low-cost DSP. Experimental results demonstrate he noise reduction performance of the hands-free unit'. [ABSTRACT FROM AUTHOR]

A steady-state sinusoidal and distortion-free excitation source is very important for the accuracy and consistency of the calibration parameters of micro-electro-mechanical systems (MEMS) inertial sensors. To solve the problem that the current MEMS inertial measurement unit (IMU) calibration device is unable to reproduce the spatial motion of linear and angular vibration coupling, research topics on the coupling vibration characteristics and parameter identification for an electromagnetic linear-angular vibration exciter are proposed. This research paper used Ampere's law and Lorentz force to establish the analytical expressions for the electromagnetic force and electromagnetic torque of the electromagnetic linear-angular vibration exciter. Then, the main purpose of this paper is to establish uniaxial and coupled vibration electromechanical analogy models containing mechanical parameters based on the admittance-type electromechanical analogy principle, and the parameter identification model is also obtained by combining the impedance formula with the additional mass method. Finally, the validity of the coupling vibration characteristics and the parameter identification model are verified by the frequency response simulation and the additional mass method, and the relative error of each parameter identification is within 5% in this paper. [ABSTRACT FROM AUTHOR]

A frequency up-conversion piezoelectric energy harvester (FUC-PEH) consists of a force amplifier, a piezoelectric stack, a low-frequency oscillator (LFO), and a stop limiter. The force amplifier generates the amplification of stress on the piezoelectric stack. The LFO, comprising a spring and a mass block, impacts the stop limiter during vibration to induce high-frequency oscillations within the piezoelectric stack. In this paper, we represent and simplify the FUC-PEH as a lumped-parameter model based on piezoelectric material constitutive equations and structural dynamic theories. Using the electromechanical analogy, we developed an equivalent circuit model (ECM) of the FUC-PEH. A parametric study was performed to investigate the impact of system parameters, such as spring stiffness and concentrated mass, on the FUC-PEH performance. The collision-induced amplitude truncation (AT) effect enlarges the operation bandwidth. ECM simulations show that low-frequency input excitation is converted into a high-frequency output response, enhancing the energy conversion efficiency. Furthermore, we aimed to improve the FUC-PEH's performance using a synchronous electric charge extraction (SECE) circuit. Using the ECM approach, we established a system-level model that considers the electromechanical coupling behavior. The simulation results provide insights into the performance of FUC harvesters with SECE circuits and offer valuable design guidance. [ABSTRACT FROM AUTHOR]

In this paper, a stochastic hybrid predator-prey model with Beddington-DeAngelis functional response and Lévy jumps is studied. Firstly, it is proved that the model has a unique global solution. Secondly, sufficient conditions for weak persistence in the mean and extinction of prey and predator populations are established. Finally, sufficient conditions for the existence and uniqueness of ergodic stationary distribution are established. Moreover, several numerical simulations are presented to illustrate the main results. [ABSTRACT FROM AUTHOR]

This paper describes the improvements in the simulation of a heavy rainfall event due to the assimilation of surface wind observations from the Oceansat-2 scatterometer using ensemble Kalman filter (EnKF) technique. A heavy rainfall event over the southern peninsular region of India during the northeast Indian monsoon season is investigated in this paper using the Advanced Research Weather Research and Forecasting model. A control (CTRL) run where no surface wind observations are assimilated, as well as a 3-D variational (3DVar) run and an EnKF run wherein surface wind observations are assimilated using the 3DVar and EnKF techniques, is performed. Results indicate that the EnKF assimilation run simulates various meteorological fields, including precipitation fields during the rainfall event, better than the CTRL and the 3DVar runs. Qualitative and quantitative comparisons with Tropical Rainfall Measurement Mission precipitation observations indicate that the rainfall simulation shows improvement due to EnKF assimilation as compared with the other two model runs. Vertical profiles of area-averaged and time-averaged relative vorticities and temperature anomalies around the low-pressure system are also better reproduced in the EnKF experiment. Considering the importance of accurate real time simulations of heavy rainfall events associated with the Indian monsoon season, this paper provides encouraging results on the utility of EnKF technique as applied over the Indian region. [ABSTRACT FROM PUBLISHER]

This paper presents the design consideration on a converged Rx surface acoustic wave (SAW) duplexer module for integrated RF front end. Two different matching-circuit and notch-circuit configurations were examined with importance placed on electrical characteristics (insertion loss and isolation of duplexer) and simplification of module, respectively. From circuit simulations and examinations, we verified that a simplified design was best in terms of both characteristics and space in the case of a finite inductor’s Q. We also fabricate a quad-band converged Rx module (Band I + II, V + VIII) using an SAW duplexer and verified that its electrical characteristics agree well with our simulation results. [ABSTRACT FROM PUBLISHER]

This paper analyzes the incline unbalanced magnetic pull (IUMP) generated in the permanent magnetic synchronous motor (PMSM) with the rotor misalignment. The motor magnetic field in such a motor is asymmetric, and both the magnitude and the action point of UMP vary in motor operation. This paper presents an analytical model for analyzing the 3-D effects of the UMP induced by the misalignment rotor. The numerical simulation results prove the effectiveness of the proposed analytic model. [ABSTRACT FROM PUBLISHER]

This paper presents an optimal control of intervention strategies for the menace of Banditry taking into account media campaign against Banditry u2(t) rehabilitation of Bandits detainees u5(t) and use of military force against Banditry u6(t) as control strategies. The Banditry free equilibrium, Banditry present equilibrium and the basic reproduction number of Banditry R0B were obtained. The stability analysis results suggest that the Banditry free equilibrium is locally asymptotically stable when R0B>1 and otherwise when R0B>1. The Boko Haram presence equilibrium is globally asymptotically stable when R0B>1 and unstable if R0B>1. We used the three control strategies and updated the Banditry menace model. The optimal control issue was resolved using Pontryagin's Maximum Principle (PMP). It was discovered that there is a significant decrease in the population of Bandits and increase in the number of rehabilitated Bandits and detained Bandits when the control measures are implemented compared to the case without control. We solved the optimality control using a forward-backward sweep strategy implemented in MATLAB for numerical simulation. Additionally, we saw that the number of people detained fluctuates as the number of people receiving rehabilitation rises. We argue that in order to lessen or completely erase the menace caused by Bandits in society, the government should fund media campaigns and rehabilitation initiatives. [ABSTRACT FROM AUTHOR]

The open shortest path first (OSPF) protocol has been widely applied to intra-domain routing in today’s Internet. Since a router running OSPF distributes traffic uniformly over equal-cost multi-path (ECMP), the OSPF-based optimal traffic engineering (TE) problem (i.e., deriving optimal link weights for a given traffic demand) is computationally intractable for large-scale networks. Therefore, many studies resort to multi-protocol label switching (MPLS) based approaches to solve the optimal TE problem. In this paper we present a generalized routing framework to realize the optimal TE, which can be potentially implemented via OSPF- or MPLS-based approaches. We start with viewing the conventional optimal TE problem in a fresh way, i.e., optimally allocating the residual capacity to every link. Then we make a generalization of network utility maximization (NUM) to close this problem, where the network operator is associated with a utility function of the residual capacity to be maximized. We demonstrate that under this framework, the optimal routes resulting from the optimal TE are also the shortest paths in terms of a set of non-negative link weights that are explicitly determined by the optimal residual capacity and the objective function. The network entropy maximization theory is employed to enable routers to exponentially, instead of uniformly, split traffic over ECMP. The shortest-path penalizing exponential flow-splitting (SPEF) is designed as a link-state protocol with hop-by-hop forwarding to implement our theoretical findings. An alternative MPLS-based implementation is also discussed here. Numerical simulation results have demonstrated the effectiveness of the proposed framework as well as SPEF. [ABSTRACT FROM AUTHOR]

This paper derives theoretical solutions for three radially layered piezoceramic/epoxy cylindrical composite transducers, which are composed of a solid epoxy disk, two axially polarized piezoceramic rings, and two epoxy rings. Two piezoceramic rings are the functional components, which can actuate and adjust the composite’s performance. According to different functions, three typical transducers are developed. The first one involves both of the two piezoceramic rings acting as actuating elements with parallel connections electrically. The other two involve only one piezoceramic ring as an actuating element, while the other ring that is connected to a resistor acts as a sensing element to adjust the electromechanical characteristics. Based on the plane stress assumption, theoretical solutions of these three transducers in radial vibration are derived, and performance differences of their electromechanical characteristics are analyzed and discussed. Furthermore, the solutions are validated by comparing with the ANSYS simulation results and the experimental data. The simulated and the measured first resonance and antiresonance frequencies are in a good agreement with the theoretical results, which validates the accuracy of the directed solution. This paper contributes to a comprehensive understanding of the proposed cylindrical composite’s electromechanical performance, which is helpful for further application in underwater sound and ultrasonic fields. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate a method to derive component metal–metal electrostatic discharge (ESD) rating from its human body model (HBM) ESD rating. Symbolic computations and equivalent circuit simulations are used for this purpose. It can be seen from the components datasheets, that the machine model (MM) rating is often ten times less than the HBM rating. This paper proposes an explanation of this dependence derived from thermal failure physics. This paper presents a method of the ESD rating estimation based on injected power or charge analysis. This estimation method also could be applied for the CDM and charged board model (CBM) cases. We obtained a good correlation of HBM and MM ratings and a limited correlation of HBM and CBM/CDM ratings. The CBM case for power mosfet also was considered. [ABSTRACT FROM AUTHOR]

The increasing use of voltage-source converters (VSCs) in modern power systems has led to extensive studies on their frequency response and stability, which are characterized by power-frequency oscillations and overshoots following a disturbance. However, the existing small-signal analysis models do not adequately describe the impact of the types of disturbance on the torque-frequency dynamics of the multi-VSC parallel system. In this paper, based on the principle of electromechanical analogy, a unified equivalent admittance modeling method is proposed by analogizing the rotor dynamic model of a synchronous generator (SG) to the circuit network, which has the advantages of simple modeling, clear physical meaning and easy expansion. Firstly, the equivalent admittance model of a single SG/VSC is established, and then easily extended to the multi-VSC system. The proposed modelling method not only applicable to a variety of VSCs, but also can handle different types of disturbance. More importantly, the circuit theory can be applied to analyze the torque-frequency dynamic characteristics. Subsequently, the equivalence between the proposed model and the state-space model under different damping terms is compared. In addition, the response characteristics of two different damping terms are compared. Next, the dynamic response characteristics of single VSC and multi-VSC parallel systems under different disturbances are analyzed. Finally, related simulations and experiments are executed to verify the accuracy and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper describes analytical prediction and measurements for the inductance profile of a linear switched reluctance motor (LSRM). First, analytical solutions for flux density due to mover winding currents are derived, for the case when the mover is located at aligned and unaligned positions. Then, using the inductance at aligned and unaligned positions obtained from two-dimensional (2-D) analytical solutions and Fourier series expansion proposed in this paper, we predict the inductance profile of the LSRM analytically. Finally, inductance measurements are given to confirm the analysis. [ABSTRACT FROM AUTHOR]

The Alberta Interconnected Electric System (AlES) forms a single integrated transmission network serving the Province of Alberta, Canada. A number of large critical industrial loads are served by the AlES. These loads operate 24 h a day and seven days a week. This paper deals with a critical industrial load which is normally supplied by the Alberta provincial grid through two 72-ky lines. This load also maintains a backup generation system consisting of a set of gas turbines to meet its operating demands in the case of Alberta grid failure. The basic objective of this paper is to derive the optimal number of gas turbines that this critical load should maintain in order to satisfy the plant's reliability criteria in the case of grid failure for continuity of its operation. A Monte Carlo simulation model is developed to assess the adequacy of the backup gas turbine system, and the results of a series of case studies performed using the developed model are presented in this paper. [ABSTRACT FROM AUTHOR]

This paper considers a profit-maximizing thermal producer that participates in a sequence of spot markets, namely, day-ahead, automatic generation control (AG C), and balancing markets. The producer behaves as a price-taker in both the day-ahead market and the AGC market but as a potential price-maker in the volatile balancing market. The paper provides a stochastic programming methodology to determine the optimal bidding strategies for the day-ahead market. Uncertainty sources include prices for the day-ahead and AGC markets and balancing market linear price variations with the production of the thermal producer. Results from a realistic case study are reported and analyzed. Conclusions are duly drawn. [ABSTRACT FROM AUTHOR]

Copyright of Information Technology & Control is the property of Kaunas University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Designers of hydraulically driven machines and devices are obliged to ensure during design process their high service life with taking into account their operational conditions. Some of the machines may be started in low ambient temperature and even in thermal shock conditions (due to delivering hot working medium to cold components). In order to put such devices into operation appropriate investigations, including experimental ones - usually very expensive and time-consuming, are carried out. For this reason numerical calculations can be used to determine serviceability of a hydraulic component or system operating in thermal shock conditions. Application of numerical calculation methods is much less expensive in comparison to experimental ones. This paper presents a numerical calculation method which makes it possible to solve issues of heat exchange in elements of investigated hydraulic components by using finite elements method. For performing the simulations the following data are necessary: ambient temperature, oil temperature, heat transfer coefficient between oil and surfaces of elements, as well as areas of surfaces being in contact with oil. By means of computer simulation method values of clearance between cooperating elements as well as ranges of parameters of correct and incorrect operation of hydraulic components have been determined. In this paper results of computer simulation of some experimentally tested hydraulic components such as axial piston pump and proportional spool valve, are presented. The computer simulation results were compared with the experimental ones and high conformity was obtained. [ABSTRACT FROM AUTHOR]

Small signal stability analysis in a power system is typically concerned with electromechanical oscillations. For this purpose, it is adequate to model the transmission system using a constant admittance matrix. For torsional oscillations and HVDC interactions, the frequency of interest is much higher and the constant admittance representation is not sufficient. This paper proposes a hybrid model, which allows the parts of the transmission network in the vicinity of HVDC converters or any other dynamic devices to be modeled with their dynamics and the remaining parts to be modeled as constant admittances. The proposed hybrid methodology for small signal stability assessment is the main contribution of this paper. The proposed methodology is validated against an electromagnetic transient simulation program (PSCADIEMTDC) using time responses. The proposed model and two other small signal models are compared against each other in the frequency domain using modal analysis. [ABSTRACT FROM AUTHOR]

This paper will present some meaningful insights into the analysis and modeling phases of an Enterprise Virtual Environment (EVE) prototype. The main goal of EVE is to provide an environment for collaborative decisions using a DSS-like approach. In the second part, the pro-posed architecture of the system will be introduced. This system is developed primarily to simulate decision situations in the academic training of students. The second goal of the system is to provide us with user activity logs that will be the starting point of decision pattern min-ing process. In the third part of the paper, we will provide evidence regarding the possibility of: mining decision models from user activity logs; comparing different decision making strategies of users; and building decision reference models. [ABSTRACT FROM AUTHOR]

This paper presents a simplified analysis of a generalized cycloconverter and suggests a new method for the estimation of the cycloconverter period as a function of the control mode. The paper presents generalized theoretical results supported by computer simulations and demonstrated by examples. [ABSTRACT FROM AUTHOR]

This paper reports a novel capacitive detection method, called the sideband-ratio (SBR) detection, which is robust to variations of such critical parameters as the nominal capacitance, frequency, and amplitude of the probing voltage and gain of the transimpedance amplifier. The approach constructively utilizes the inherent nonlinearity of parallel-plate sense capacitors in order to measure the amplitude of sinusoidal motion. In the case of parallel-plate detection signal, multiple harmonics exist and each carry information about the amplitude of mechanical motion. The SBR method robustly extracts the amplitude of motion from the ratio of multiple sidebands. This paper presents theoretical background and analysis of this nonlinear measurement method. A real-time measurement algorithm is implemented in software and simulated. Feasibility of the developed approach is demonstrated experimentally. [ABSTRACT FROM AUTHOR]

The problem of locating the sources of harmonic distortion in power networks is still a critical task. Several methods based on multipoint measurement techniques have been recently proposed in the literature for harmonic-pollution monitoring. The main goal of this paper is to compare the two most powerful tools designed for this purpose. In this paper, the results of both computer simulations on an IEEE test network and experimental tests performed by means of simultaneous measurements on an ad hoc benchmark power system are presented along with a discussion on the practical usability of such monitoring techniques. [ABSTRACT FROM AUTHOR]

Within an optimal power flow market clearing framework, this paper provides expressions to compute the sensitivities of locational marginal prices with respect to power demands. Sensitivities with respect to other parameters can also be obtained. An example and a case study are used to illustrate the expressions derived. [ABSTRACT FROM AUTHOR]

This paper addresses the design and implementation of a novel control scheme for a doubly fed induction generator (DFIG), of the type employed with wind turbines, to provide support to power system operation. It is shown that this controller provides a DFIG-based wind farm with operational and control compatibility with conventional power stations, the ability to contribute to voltage support and recovery following network faults, the ability to provide a power system stabilizer capability that improves overall system damping, and the capability of contributing short-term frequency support following loss of network generation. A simple but realistic test network that combines synchronous and wind farm generation has been modeled and used to assess dynamic performance. Simulation results are presented and discussed that demonstrate the capabilities and contributions of the new DFIG controller to network support. [ABSTRACT FROM AUTHOR]

This paper presents a systematic way of using linear analysis techniques to find and rank candidate locations for controlled shunt and series compensations for power system damping purposes. A two-stage approach based on frequency response computations is introduced using a 4780-bus system model of the Nordic power system for assessment of controlled shunt compensations. In the first stage, their controllability is determined by means of long-distance frequency responses. In the second stage, the frequency responses of the transfer functions from the bus shunt susceptance to the bus voltage magnitude are computed for buses that have shown high controllability. This paper shows that the interpretation of the frequency responses of these local transfer functions, for buses that have exhibited high controllability, is in most cases sufficient to predict the behavior of controlled shunt compensation at different locations in the system. The interpretation is based on the observation of amplitudes, phase angles, and the rate of change of the phase angles around the interarea resonance frequencies. An important finding was that controlled shunt compensation located in an area with high-power import over ac interconnections lowered the damping of at least one of the interarea oscillation modes if operating in normal voltage control. This finding was also verified with nonlinear simulations. The first stage of the proposed frequency response-based approach has also been introduced for assessment of controlled series compensations. The strength of the new methods is that they can be used with both linear and nonlinear system models. [ABSTRACT FROM AUTHOR]

This paper presents a performance analysis of the maximum likelihood (ML) estimator for finding the directions of arrival (DOAs) with a sensor array. The asymptotic properties of this estimator are well known. In this paper, the performance under conditions of low signal-to-noise ratio (SNR) and a small number of array snapshots is investigated. It is well known that the ML estimator exhibits a threshold effect, i.e., a rapid deterioration of estimation accuracy below a certain SNR or number of snapshots. This effect is caused by outliers and is not captured by standard techniques such as the Cramér-Rao bound and asymptotic analysis. In this paper, approximations to the mean square estimation error and probability of outlier are derived that can be used to predict the threshold region performance of the ML estimator with high accuracy. Both the deterministic ML and stochastic ML estimators are treated for the single-source and multisource estimation problems. These approximations alleviate the need for time-consuming computer simulations when evaluating the threshold region performance. For the special case of a single stochastic source signal and a single snapshot, it is shown that the ML estimator is not statistically efficient as SNR → ∞ due to the effect of outliers. [ABSTRACT FROM AUTHOR]

Utilization of hydraulic-fracturing technology is dramatically increasing in exploitation of natural gas extraction. However the prediction of the configuration of propagated hydraulic fracture is extremely challenging. This paper presents a numerical method of obtaining the configuration of the propagated hydraulic fracture into discrete natural fracture network system. The method is developed on the basis of weighted fracture which is derived in combination of Dijkstra's algorithm energy theory and vector method. Numerical results along with experimental data demonstrated that proposed method is capable of predicting the propagated hydraulic fracture configuration reasonably with high computation efficiency. Sensitivity analysis reveals a number of interesting observation results: the shortest path weight value decreases with increasing of fracture density and length, and increases with increasing of the angle between fractures to the maximum principal stress direction. Our method is helpful for evaluating the complexity of the discrete fracture network, to obtain the extension direction of the fracture. [ABSTRACT FROM AUTHOR]

Several different seismic active control algorithms have been proposed in the last decades, most of these studies are based on the applications of the traditional linear quadratic regulator control (LQR). This paper develops a new control algorithm for SDOF structures based in Lyapunov method. This algorithm uses Lyapunov's direct approach for stability analysis in design of feedback controller. The approach requires the use of Lyapunov function candidate, which must be a positive definite function of the states of the system. The controller is designed so as to make the derivative of the Lyapunov function negative semidefinite. Numerical simulations using one story frame structure modeled as shear building structure subjected to earthquake excitations have been performed to evaluate the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

A network is considered observable if its current state can be determined in finite time from knowledge of the observed states. The observability transitions in networks based on random or degree-correlated sensor placement have recently been studied. However, these placement strategies are predominantly based on local information regarding the network. In this paper, to understand the phase transition process of network observability, we analyze the network observability transition for a betweenness-based sensor placement strategy, in which sensors are placed on nodes according to their betweenness. Using numerical simulations, we compute the size of the network’s largest observable component (LOC) and compare the observability transitions for different sensor placements. We find that betweenness-based sensor placement can generate a larger LOC in the observability transition than the random or degree-based placement strategy in both model and real networks. This finding may help to understand the relationship between network observability and the topological properties of the network. [ABSTRACT FROM AUTHOR]

The paper focuses on a nonlinear model to represent the mechanical behaviour of a mix coil spring - rubber used in the secondary suspension of passenger rail vehicles. The principle of the model relies on overlapping of the forces corresponding to three components - the elastic component, the viscous component and the dry friction component. The model has two sources on non-linearity, in the elastic force and the friction force, respectively. The main attributes of the model are made visible by its response to an imposed displacement-type harmonic excitation. The results thus obtained from the applications of numerical simulation show a series of basic properties of the model, namely the dependence on amplitude and the excitation frequency of the model response, as well as of its stiffness and damping. [ABSTRACT FROM AUTHOR]

Numerical simulation of shielding effectiveness (SE) of a perforated shielding enclosure is carried out, using the finite element method (FEM). Possibilities of model definitions and differences between 2D and 3D models are discussed. An important part of any simulation is verification of the model results-here the simulation result are verified in terms of convergence of the model in dependence on the degrees of freedom (DOF) and by measurements. The experimental method is based on measurement of electric field inside the enclosure using an electric field probe with small dimensions is described in the paper. Solution of an illustrative example of SE by FEM is shown and simulation results are verified by experiments. [ABSTRACT FROM AUTHOR]

The paper presents another phase of the study aimed at determining distributions of random pulses forcing vibration of an oscillator with damping. At this stage, the impact of the pulses amplitudes on distributions determined in a finite time interval is discussed. Application of a mathematical model in simulations allows to determine the differences between the distributions generated in MATLAB environment and those determined by a function. The experiment was designed so that the qualitative analysis of the issue was possible. [ABSTRACT FROM AUTHOR]

This paper deals with studying of two topics – measuring of velocity profile deformation behind a over-flooded construction and modelling of this velocity profile deformation by computational fluid dynamics (CFD). Numerical simulations with an unsteady RANS models - Standard k-ε, Realizable k-ε, Standard k-ω and Reynolds stress models (ANSYS Fluent v.18) and experimental measurements in a laboratory flume (using ADV) were performed. Results of both approaches showed and affirmed presence of velocity profile deformation behind the obstacle, but some discrepancies between the measured and simulated values were also observed. With increasing distance from the obstacle, the differences between the simulation and the measured data increase and the results of the numerical models are no longer usable. [ABSTRACT FROM AUTHOR]

This paper proposes improving the directivity of microstrip patch antennas (MPAs) by using metamaterials. Four different metamaterial types are used as a at lens in front of the MPA, respectively, which are tuned to 12 GHz (Ku-band) resonance frequency. Thus, it can be decided which metamaterial is more proper for antenna directivity enhancement at this band. One additional new metamaterial structure is proposed in this paper, which is called a Euro-shaped resonator, and other metamaterials used are the triangular split ring resonator, symmetrical ring structure, and split ring resonator. The permeability and permittivity of metamaterials are extracted from the S parameters by using a robust method. Microwave Studio by Computer Simulation Technology is used for modeling and simulation. The MPA and metamaterials are fabricated, and measurements are performed in the Yíldíz Technical University RF and Microwave Laboratory. It is observed that measured results are in close agreement with the computer simulations. [ABSTRACT FROM AUTHOR]

A superconducting transformer with the windings made of second-generation high-temperature superconducting (HTS) tape can limit short-circuit current effectively. Despite this, due to the small cross-section of normal metal layers and low thermal capacity of windings, fault current must be switched OFF by an additional device in relatively short time to prevent a catastrophic temperature rise. The paper presents the computer simulation of short-circuit fault suppressed by a single-phase 10 kVA superconducting transformer. Numerical results were comparedwith experimental data to validate the model. Authors attempted to extend the method to an industrial size HTS transformer and estimate the dimensions of copper cowindings. [ABSTRACT FROM AUTHOR]

In the present paper, experimental and numerical studies of a newly developed process of Hot-Blade Cutting used for free forming of double-curved surfaces and cost effective rapid prototyping of expanded polystyrene foam is carried out. The experimental part of the study falls in two parts. The first presents a number of large-scale cutting samples combining linear cuts with and without inclination measured from the horizontal direction of cutting, while in the second, the thermal phenomena in the process are studied based on infrared measurements of the hot-blade tool made by observation during the cutting process. A novel measurement method for determination of kerfwidth (i.e., the gap space after material removal) applying a commercially available large-scale optical 3D scanning technique was developed and used. A one-dimensional thermo-electro-mechanical numerical model for Hot-Blade Cutting similar to the one previously proposed by Petkov and Hattel (Int J Machine Tools Manuf 107:50-59 2016) for Hot-Wire Cutting of Polystyrene foam is used to simulate the process and describe the effects taking place within the hot-blade during different cutting procedures. The obtained results are graphically presented and discussed in relation to the aim for higher geometrical accuracy of the Hot-Blade Cutting process. [ABSTRACT FROM AUTHOR]

Personalization is a key aspect of biophysical models in order to impact clinical practice. In this paper, we propose a personalization method of electromechanical models of the heart from cine-MR images based on the adjoint method. After estimation of electrophysiological parameters, the cardiac motion is estimated based on a proactive electromechanical model. Then cardiac contractilities on two or three regions are estimated by minimizing the discrepancy between measured and simulation motion. Evaluation of the method on three patients with infarcted or dilated myocardium is provided. [ABSTRACT FROM PUBLISHER]

Micro Electromechanical Systems (MEMS) based microfluidic devices have gained popularity in biomedicine field over the last few years. In this paper, a comprehensive overview of microfluidic devices such as micropumps and microneedles has been presented for biomedical applications. The aim of this paper is to present the major features and issues related to micropumps and microneedles, e.g., working principles, actuation methods, fabrication techniques, construction, performance parameters, failure analysis, testing, safety issues, applications, commercialization issues and future prospects. Based on the actuation mechanisms, the micropumps are classified into two main types, i.e., mechanical and non-mechanical micropumps. Microneedles can be categorized according to their structure, fabrication process, material, overall shape, tip shape, size, array density and application. The presented literature review on micropumps and microneedles will provide comprehensive information for researchers working on design and development of microfluidic devices for biomedical applications. [ABSTRACT FROM AUTHOR]

Direct simulation of the starting process of an electric machine using a 3-D transient finite-element analysis (FEA) is very time consuming. To overcome this difficulty, an interpolative finite-element modeling of a large solid pole synchronous motor (SPSM) is presented and its starting process is simulated in this paper. In order to take into account the effects of cooling ducts and end turns, three different simplified 3-D finite-element models (FEMs) are proposed to reduce the computing time and save memory storage. With the proposed algorithm, an appropriate postprocess is exploited to deduce an effective core length and an end-turn leakage inductance. Then, a 2-D transient FEM with the modified parameters from 3-D FEA is used to simulate the starting process. The proposed method is validated by the test results of a 15000-hp, 13.2-ky, 4-pole SPSM. [ABSTRACT FROM AUTHOR]

In this paper, two novel voltage-mode (VM) single- input-three-output (SITO) second-order multifunction analog filters for simultaneously realizing low-pass, bandpass, and high-pass responses from the same topology are proposed. They employ a single dual-output differential voltage current conveyor (DVCC), two grounded capacitors, and three resistors. Both of the proposed filters offer the following two important features: the simultaneous realization of low-pass, bandpass, and high-pass responses and the use of a minimum number of grounded capacitors and a single DVCC. The nonideal gain effects of the developed structures are examined. To show the performance of the proposed VM filters, computer simulation results using the SPICE program, together with ideal ones, are drawn. [ABSTRACT FROM AUTHOR]

Nano electromechanical systems (NEMS) represent an important new class of device with wide ranging applications. In this paper we report proposals and calculations for novel methods for excitation and readout of cantilever-style NEMS resonators which are applicable over a wide temperature range. We suggest a Lorentz force-based excitation method and discuss an ultrasensitive readout provided by a nanoSQUID, where the cantilever vibration modulates the inductance of the nanoSQUID loop, allowing potentially sub-picometer amplitude sensitivity to be achieved. [ABSTRACT FROM AUTHOR]

This paper presents a novel initial value compensation (IVC) using an additional input for semi-closed control systems. The authors have already proposed the IVC approach using the additional input for residual vibration suppression in the fast and precise positioning control. In the approach, however, an essential subject has remained, i.e., the positioning control in the load side could not satisfy the required performance because the systems have been constructed under the assumption of a semi-closed control system. An improvement of the control performance in load position, therefore, is discussed in this paper, where the appropriate assignments of poles and zeros in IVC are ensured, considering the transfer functions of position in both sensor and load for the control initial values. The effectiveness of the proposed approach has been verified by numerical simulations and experiments using a prototype. [ABSTRACT FROM AUTHOR]

IEEE802.11DCF employs RTS/CTS (Request To Send/Clear To Send) mechanism for mitigating effect of hidden terminals. The RTS/CTS mechanism sets transmission deferral timer to neighbor terminals by exchanging RTS and CTS between transmitter and receiver. Then, in the case that RTS/CTS exchange succeeds, effect of hidden terminals could be suppressed, otherwise, any neighbor which received RTS and/or CTS defers its new transmission needlessly although DATA packet corresponding to the previous RTS/CTS exchange will not be transmitted. In this paper, we propose Cancel CTS, procedure in order to cope with the unnecessarily transmission deferment. Results of computer simulation confirms that our method well improves the throughput performance of IEEE802.11DCF. [ABSTRACT FROM AUTHOR]

This paper presents an adaptive digital signal processing technique that cancels self-image interference due to frequency-independent, in-phase/quadrature-phase (I/Q) mismatch in zero-intermediate frequency (IF) direct-conversion receivers. The proposed technique, which is referred to as the normalized least-mean square adaptive self-image cancellation (NLMS-ASIC) algorithm, is an ASIC technique that controls the filter weight to minimize the power of the filter output signal using an NLMS type of weight-control mechanism. Some closed-form equations are derived for the mean-squared error (MSE), as well as the mean image-rejection ratio (IRR) of the proposed NLMS-ASIC algorithm. In particular, a step-size determination method is explained so that the requirements on the image-rejection performance and convergence time can be satisfied. The advantages of the proposed technique are demonstrated through computer simulations. [ABSTRACT FROM AUTHOR]

Simulation optimization is providing solutions to important practical problems previously beyond reach. This paper explores how new approaches are significantly expanding the power of simulation optimization for managing risk. Recent advances in simulation optimization technology are leading to new opportunities to solve problems more effectively. Specifically, in applications involving risk and uncertainty, simulation optimization surpasses the capabilities of other optimization methods not only in the quality of solutions but also in their interpretability and practicality. In this paper, we demonstrate the advantages of using a simulation optimization approach to tackle risky decisions, by showcasing the methodology on two popular applications from the areas of finance and business process design. [ABSTRACT FROM AUTHOR]

In this paper, the nonideality effects such as non- ideal gain and parasitic-impedance effects on the low-frequency performance of two new grounded inductor simulators are in- vestigated in great depth. In addition, some low-frequency- performance improvement methods for grounded inductor simulators are discussed. Both of the grounded simulated inductors derived from the previously published ones employ a minimum number of grounded passive components and plus-type second-generation current conveyors. Four second-order voltage- mode universal-filter topologies, three of which are novel, are derived from newly and previously developed simulated inductors as application examples. Computer simulations with SPICE program including ideal and experimental test results are drawn to verify theoretical ones. [ABSTRACT FROM AUTHOR]

In many engineering applications we deal with constrained optimization problems with respect to complex-valued matrices. This paper proposes a Riemannian geometry approach for optimization of a real-valued cost function ∫ of complex-valued matrix argument W, under the constraint that MT is an n x n unitary matrix. We derive steepest descent (SD) algorithms on the Lie group of unitary matrices U(n). The proposed algorithms move towards the optimum along the geodesics, but other alternatives are also considered. We also address the computational complexity and the numerical stability issues considering both the geodesic and the nongeodesic SD algorithms. Armijo step size [1] adaptation rule is used similarly to [2], but with reduced complexity. The theoretical results are validated by computer simulations. The proposed algorithms are applied to blind source separation in MIMO systems by using the joint diagonalization approach [3]. We show that the proposed algorithms outperform other widely used algorithms. [ABSTRACT FROM AUTHOR]