bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical investigation of the 3D vibrational behaviour of skewed induction machines due to rotating force waves
Authors: Weilharter Bernhard , Bíró Oszkár , Rainer Siegfried 
Published: March 2013

PurposeThe purpose of this paper is to analyse the surface vibrations of an induction machine due to force waves acting on the stator and rotor core. The focus lies on the investigation of the influence of force waves with axial variation and with higher spatial ordinal numbers on the surface vibration of an induction machine and thus its emitted noise.Design/methodology/approachUnit force waves with different spatial ordinal numbers and varying in axial direction are set up and applied on the stator and rotor teeth of a structural finite element model of an induction machine. Structural harmonic analyses with different frequencies are performed and the deformation of the machine is determined. After that, the root mean square of the normal component of the velocity on the surface of the machine's housing is determined and compared for the different force waves.FindingsThe influence of force waves with spatial ordinal numbers of higher order can have a significant influence on the structural vibration, especially if the spatial ordinal number is near the number of teeth. Furthermore, it is shown that the structure may react sensitively to axial variations of the forces, particularly near distinct structural resonances.Originality/valueThe presented investigations show relevant issues influencing the noise behaviour of electrical machines.
Exploration versus exploitation using kriging surrogate modelling in electromagnetic design
Authors: Xiao Song , Rotaru Mihai , Sykulski Jan K. 
Published: March 2013

PurposeDesign optimisation of electromagnetic devices is computationally expensive as use of finite element or similar codes is normally required. Thus, one of the objectives is to have efficient algorithms minimising the number of necessary function calls. In such algorithms a balance between exploration and exploitation needs to be found not to miss the global optimum but at the same time to make efficient use of information already found. The purpose of this paper is a contribute to the search of such efficient algorithms.Design/methodology/approachThis paper discusses the use of kriging surrogate modelling in multiobjective design optimisation in electromagnetics. The investigation relies on the use of special test functions.FindingsThe importance of achieving appropriate balance between exploration and exploitation is emphasised when searching for the global optimum. New strategies are proposed using kriging.Originality/valueIt is argued that the proposed approach will yield a procedure to solve time consuming electromagnetic design problems efficiently and will also assist the decision making process to achieve a robust design of practical devices considering tolerances and uncertainties.
Algebraic identification of a stable first‐order plus time delay model from step response
Authors: Ibn Taarit Kaouther , Ksouri Mekki 
Published: March 2013

PurposeA fast identification algorithm for a linear monotonic process from a step response is proposed in this paper, from which the parameters of a first‐order plus dead‐time model can be obtained directly.Design/methodology/approachThe study is based on a non‐asymptotic distributional estimation technique initiated without delay in the framework of systems. Such a technique leads to simple realization schemes, involving integrators, multipliers and piecewise polynomial or exponential time functions and shows a possible link between simultaneous identification and generalized eigenvalue problems. Thus, it allows for a real‐time implementation.FindingsThe effectiveness of the identification method has been demonstrated through a number of simulation examples and a real‐time test.Originality/valueThis paper presents a novel method to simultaneous delay and parameters identification of a stable first‐order plus time delay model from step response that can model a widespread class of systems.
Proximity‐effect winding loss in different conductors using magnetic field averaging
Authors: Piotr Wojda Rafal , Kazimierz Kazimierczuk Marian 
Published: March 2013

PurposeThe purpose of this paper is twofold. First, it aims to study the proximity‐effect power loss in the foil, strip (rectangular), square, and solid‐round wire inductor windings. Second, it aims to optimize the thickness of the foil, strip, square wire windings, and the diameter of the solid‐round‐wire, the minimum of winding AC resistance and the minimum of winding AC power loss for sinusoidal inductor current.Design/methodology/approachThe methodology of the analysis is as follows. First, the winding resistance of the single‐layer foil winding with a single turn per layer and uniform magnetic flux density B is derived. Second, the single‐layer foil winding with uniform magnetic flux density B is converted for the case, where the magnetic flux density B is a function of x. Third, the single‐layer winding is replaced by the winding with multiple layers isolated from each other. Fourth, transformation of the multi‐layer foil winding into different conductor shapes is performed. For the solid‐round‐wire windings, the results of the derivation are compared to Dowell's equation and verified by measurements.FindingsClosed‐form analytical equations for the optimum normalized winding size (thickness or diameter) at the global or local minimum of winding AC resistance are derived. It has been shown that the AC‐to‐DC winding resistance ratio is equal to 4/3 (FRv=4/3) at the optimum normalized thickness of foil and strip wire winding hopt/δw. The AC‐to‐DC winding resistance ratio is equal to 2 (FRv=2) at the local minimum of the square wire and solid‐round‐wire winding AC resistances. Moreover, it has been shown that for the solid‐round wire winding, the proximity‐effect AC‐to‐DC winding resistance ratio is equal to Dowell's AC‐to‐DC winding resistance ratio at low and medium frequencies. The accuracy of equation for the winding AC resistance of the solid‐round wire winding inductors has been experimentally verified. The predicted results were in good agreement with the measured results.Research limitations/implicationsIt is assumed that the applied current density in the winding conductor is approximately constant and the magnetic flux density B is parallel to the winding conductor (b>>h). This implies that a low‐ and medium‐frequency 1‐D solution is considered and allows the winding size optimization. This is because the optimum normalized winding conductor size occurs in the low‐ and medium‐frequency range. The skin‐effect winding power loss is much lower than the proximity‐effect winding power loss and therefore, it is neglected.Originality/valueThis paper presents derivations of closed‐form analytical equations for the optimum size (thickness or diameter) that yields the global minimum or the local minimum of proximity‐effect loss. A significant advantage of these derivations is their simplicity. Moreover, the paper derives equations for the AC‐to‐DC winding resistance ratio for the different shape wire windings, i.e. foil, strip, square and solid‐round, respectively.
A low complexity multi‐user detector based on G‐SIC and PIC for DS/CDMA systems
Authors: Yekhlef Mohammed , Saidi Lamir 
Published: March 2013

PurposeThe purpose of this work is to propose a new multi‐user detector which cascades the linear G‐SIC with some linear PIC stages to form a new linear hybrid multi‐user detector.Design/methodology/approachMultistage interference cancellation multi‐user detectors became an increasingly important area of research due to their relative low computational complexity. The performance comparison of the proposed linear HIC is studied and presented using matlab environment to investigate the bit error rates. For DS/CDMA system, each user is characterized by its own code. The signals from users are spread by appropriately design sequences and then transmitted over an AWGN channel with BPSK modulation.FindingsBy the cascade of the linear G‐SIC and the traditional PIC, a low complexity multi‐user detector is found capable of reducing the long detection delay compared with the linear G‐SIC. The advantages of the linear G‐SIC and PIC can be exploited substantially.Originality/valueThe paper proposes an algorithm that can combat the MAI with less complexity, and also can speed the convergence compared with other detectors.
Voltage sag independent operation of induction motor based on Z‐source inverter
Authors: Flisar Uroš , Vončina Danijel , Zajec Peter 
Published: March 2013

PurposeThe purpose of this paper is to investigate the impact of different distribution of shoot through mode on Z‐source inverter efficiency and particularly on complexity of switching pattern generation. Switching pattern generation has been optimized for field‐oriented control (FOC) of induction motor operating beyond its nominal speed which can be easily accomplished due to the input voltage boosting implemented inherently by Z‐source inverter. The proposed drive is unaffected to supply voltage sags, too.Design/methodology/approachThe space vector modulation switching pattern of the traditional FOC drive was modified in order to insert shoot through mode necessary for input voltage boosting. Since this can be accomplished only on account of zero mode of the inverter, the active modes have to be reduced. Consequently, the output voltage space vector has to be reduced, as well.FindingsIn order to maximize profit of the input DC voltage and to omit the output voltage distortion, mathematical limitations have been derived giving the optimal boost ratio for required output voltage and ride‐through capability during voltage sags.Practical implicationsThe experimental tests of upgraded FOC of induction motor with the proposed distribution of shoot through mode in the switching pattern of Z‐source inverter and optimized control of inverter voltage are demonstrated. It is also shown that such a drive can withstand a long period of input voltage sags and operate in a broader field weakening regime.Originality/valueThe paper's value lies in the overall, DSP‐based control of the induction motor supplied with Z‐source inverter gaining the maximum utilization of the input DC supply source and optimum trade‐off between inverter efficiency and inverter components voltage stress.
Reflections on current components according to CPC concept in a single phase circuit with nonsinusoidal voltage and current waveforms and LTI load
Authors: Hartman Marek T. 
Published: March 2013

PurposeThe purpose of this paper is to show the limitation of current physical components (CPC) concept in a practical application.Design/methodology/approachThe study proposes using the sum of active and scattered currents in the compensation procedure of the reactive current according to Czarnecki's concept as well as in scattered current elimination, to get the optimal energy transfer from the source supply to the load.FindingsThe results show that CPC concept can be apply only when supply circuit voltage does not consist of interharmonics or/and subharmonics. It can also be shown that elimination of particular harmonics of the scatter current cannot be applied in practice due to the change of active power in the circuit. Only complete elimination of scatter current, e.g. by an active filter is possible without any change of active power.Practical implicationsThe paper provides new information about CPC practical implementation.Originality/valueThis paper presents new features of CPC concept.
The effects of finite metallisation thickness and conductivity in microstrip lines
Authors: Gao Bo , Tong Ling , Gong Xun 
Published: March 2013

PurposeThe purpose of this paper is to study and discuss the effects of the finite metallisation thickness and conductivity on the properties of microstrip lines.Design/methodology/approachEffective dielectric constant and attenuation constant of microstrip lines with finite metallization thickness and finite conductivity are analyzed by the method of lines. The experimental results are obtained by using Vector Network Analyzer and the 3680 V Universal Test Fixture of Anritsu.FindingsThe strip thickness has a great impact on the attenuation constant of the microstrip lines. The effects can be divided into three parts by the relationship between strip thickness (t) and skindepth (δ). When t<δ, the attenuation constant will decrease rapidly as the strip thickness increase. When δ < t<2δ, the attenuation constant still decrease rapidly as the strip thickness increase, but the slope of the curve will be smaller. When 2δ < t, the effects of the strip thickness will become insignificant and the attenuation constant still decrease slowly as the strip thickness increase.Originality/valueThis paper presents some useful principles about the effects of the finite metallization thickness and finite conductivity in microstrip lines. The reasons for these effects are discussed by analyzing the longitudinal electric field distribution in the strip. Finally, some experimental results are given to verify these principles.
Study of synchronization test methods of NoC at multi‐clock domains
Authors: Jiang Shu‐yan , Luo Gang , Chen Su , Zhao Wen‐han , Zhou Qi‐zhong 
Published: March 2013

PurposeThe purpose of this paper is to introduce several synchronization test methods of Network‐on‐Chip (NoC) at multi‐clock domains by digital logic circuits.Design/methodology/approachFirst, the authors gave the structure of NoC, the test methods for NoC in multi‐clock domains, including Built‐in Self Test (BIST) structure and the architecture of embedded core test. Then the authors approached four different synchronization structures: two‐level trigger, two kinds of lock methods, toggle and pulse synchronization methods. Based on the NoC work conditions, the authors built the experiment structures of different methods, and obtained the experiment results at high frequencies.FindingsFrom the experiments at high frequency, it can be seen that the methods of toggle and the pulse methods are prone to failed synchronization. Therefore, the lock method is more appropriate for NoC under multiple clock domains.Originality/valueIn this paper, several synchronization test methods of NoC at multi‐clock domains are discussed and compared, and the best one determined.
Alleviating the sparsity problem of collaborative filtering using rough set
Authors: Zhang Song , Li Cong , Ma Li , Li Qi 
Published: March 2013

PurposeThe purpose of this paper is to introduce an improved nearest‐neighbor collaborative filtering algorithm based on rough set theory to alleviate the sparsity problem of collaborative filtering. With experimentations, the new algorithm is thereafter evaluated.Design/methodology/approachNearest‐neighbor algorithm is the earliest proposed and the main collaborative filtering recommendation algorithm, and its recommendation quality is seriously influenced by the sparsity of user ratings. By using rough set theory, the nearest‐neighbor collaborative filtering algorithm can be improved in the sparsity data situation. The union of user rating items is used as the basis of similarity computing among users, and then a rating predicting method based on rough set theory is proposed to estimate missing values in the union of user rating items for decreasing sparsity.FindingsThe sparsity problem of collaborative filtering can be alleviated by using the union of user rating items and estimating missing values based on rough set theory. The experimental results show that the new algorithm can efficiently improve recommendation quality of collaborative filtering.Originality/valueThe union of user rating items was used as the basis of similarity computing among users. A rating prediction method based on rough set theory with an assistant method was proposed to complete the missing values in the union of user rating items. Orthogonal list was used to storage user‐item ratings matrix.
SOC HW/SW co‐verification based debugging technique
Authors: Ruan A.W. , Li C.Q. , Song Z.J. , Li W.C. 
Published: March 2013

PurposeIncreasingly complex and sophisticated VLSI design, coupled with shrinking design cycles, requires shorter verification time and efficient debug method. Logic simulation provides SoC verification with full controllability and observability, but it suffers from very slow simulation speed for complex design. Using hardware emulation such as FPGA can have higher simulation speed. However, it is very hard to debug due to its poor visibility. SOC HW/SW co‐verification technique seems to draw a balance, but Design Under Test (DUT) still resides in FPGA and remains hard for debugging. The purpose of this paper is to study a run‐time RTL debugging methodology for a FPGA‐based co‐verification system.Design/methodology/approachThe debugging tools are embedded in HDL simulator using Verilog VPI callback, so signals of testbench and internal nodes of DUT can be observed in a single waveform and updated as simulation runs, making debugging more efficient. The proposed debugging method connects internal nodes directly to a PCI‐extended bus, instead of inserting extra scan‐chain logic, so the overhead for area is reduced.FindingsThis method provides internal nodes probing on an event‐driven co‐verification platform and achieves full observability for DUT. The experiment shows that, compared with a similar method, the area overhead for debug logic is reduced by 30‐50 per cent and compile time is shortened by 40‐70 per cent.Originality/valueThe proposed debugging technique achieves 100 per cent observability and can be applied to both RTL and gate‐level verification. The debugging tool is embedded into HDL simulator using Verilog VPI callback, so DUT signals are displayed together with testbench signals in the same waveform viewer. New value of DUT signal is read from FPGA whenever it changes, which allows run‐time debug.
A hybrid biogeography‐based optimization with simplex method and its application
Authors: Ping Zhang , Ping Wei , Chun Fei , Hong‐yang Yu 
Published: March 2013

PurposeThis paper proposes a hybrid biogeography‐based optimization (BBO) with simplex method (SM) algorithm (HSMBBO).Design/methodology/approachBBO is a new intelligent optimization algorithm. The global optimization ability of BBO is better than that of genetic algorithm (GA) and particle swarm optimization (PSO), but BBO also easily falls into local minimum. To improve BBO, HSMBBO combines BBO and SM, which makes full use of the high local search ability of SM. In HSMBBO, BBO is used firstly to obtain the current global solution. Then SM is searched to acquire the optimum solution based on that global solution. Due to the searching of SM, the search range is expanded and the speed of convergence is faster. Meanwhile, HSMBBO is applied to motion estimation of video coding.FindingsIn total, six benchmark functions with multimodal and high dimension are tested. Simulation results show that HSMBBO outperforms GA, PSO and BBO in converging speed and global search ability. Meanwhile, the application results show that HSMBBO performs better than GA, PSO and BBO in terms of both searching precision and time‐consumption.Originality/valueThe proposed algorithm improves the BBO algorithm and provides a new approach for motion estimation of video coding.
Research on convergence of ACO subset algorithms
Authors: Chen Wenyu , Bian Wangyang , Zeng Ru 
Published: March 2013

PurposeThe purpose of this paper is to show that the theoretical proofs of convergence in solution of ant colony optimization (ACO) algorithms have significant values of theory and application.Design/methodology/approachThis paper adapts the basic ACO algorithm framework and proves two important ACO subclass algorithms which are ACObs,τmin  and ACObs,τmin (t).FindingsThis paper indicates that when the minimums of pheromone trial decay to 0 with the speed of logarithms, it is ensured that algorithms can, at least, get a certain optimal solution. Even if the randomicity and deflection of random algorithms are disturbed infinitesimally, algorithms can obtain optimal solution.Originality/valueThis paper focuses on the analysis and proof of the convergence theory of ACO subset algorithm to explore internal mechanism of ACO algorithm.
Antecedents and consequences of e‐business adoption for European retailers
Authors: Bordonaba‐Juste Victoria , Lucia‐Palacios Laura , Polo‐Redondo Yolanda 
Published: March 2013

PurposeThe purpose of this paper is to contribute to the discussion related to the antecedents of the extent of e‐business use and the effect of this level on changing strategy, management and marketing.Design/methodology/approachThe authors use data from 691 retailers in seven European countries. Information is obtained from the survey of the “e‐Business W@tch”. Data analysis was performed using biprobit estimation. The sample is divided into two groups depending on the level of e‐commerce of the countries.FindingsResults suggest that the e‐business use implies changes in the firm's strategy, management and marketing in all the countries studied. Differences between the two groups of countries are minimal. The main factors that influence the level of e‐business use are IT expertise and perceived benefits.Research limitations/implicationsThe limitations are related to the nature of the data and concretely the main limitation lies in the consequences construct. The data provided are very general and it would be useful to specify what kind of change is generated.Practical implicationsAntecedents of the level of use are similar for all the countries, so there might be additional factors that explain why, in some countries, retailers have adopted a different level of e‐business. Managers have to take into account that the adoption and use of a higher level of e‐business requires changes in all the functional areas. The decision of adopting and using e‐business should be taken seriously.Originality/valueMost research has focused on analyzing the antecedents of e‐business use in a single country. However, this paper presents some new evidence on the factors that influence the extent of e‐business use for two groups of countries. Furthermore, previous research has suggested that changes might be necessary within the firm due to the e‐business use but there is little empirical evidence on the internal impact of e‐business use. This paper provides a first approximation to the general areas in which managers had to made changes.