ACES Publication Search
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| Title: | ACES October 2011 Full Journal |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 6128 KB |
| Title: | ACES October 2011 Front/Back Matter |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 989 KB |
| Title: | Axisymmetric Electromagnetic Resonant Cavity Solution by a Meshless Local Petrov-Galerkin Method |
| Abstract: | This work describes a meshless approach to obtain resonant frequencies and field distributions in axisymmetric electromagnetic cavities. The meshless local Petrov-Galerkin is used with shape functions generated by moving least squares. Boundary conditions are imposed by a collocation method that does not require integrations. The proposed analysis has simple implementation and reduced computational effort. Results for TE and TM modes of cylindrical and spherical cavities are presented and compared with analytical solutions. |
| Author(s): | R. D. Soares, R. C. Mesquita, F. J. S. Moreira |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 858 KB |
| Title: | Optimization for Weighed Cooperative Spectrum Sensing in Cognitive Radio Network |
| Abstract: | In this paper, an optimal weighed cooperative spectrum sensing strategy based on data fusion is investigated in cognitive radio network. Cognitive radios sense the channels by energy detection independently and send their results to a fusion center, in which the observed data are fused by the specific weighing. The optimal sensing problem, which seeks to minimize interference and maximize throughput by keeping the probabilities of false alarm and detection within the allowable limit, is formulated. In particular, both the cooperative detections in single channel and multi-channels are analyzed, and the optimal weighed factors are obtained by Cauchyinequality. Based on the weighing, we transform the non-convex optimal problem of multi-channel sensing with double parameters and nonlinear constraints into a convex problem with single parameter and linear constraints, which can be easily solved. The simulation shows that the proposed algorithm can achieve lower interference and higher throughput with less computing complexity, and the detected performance of each sub-channel can also be guaranteed. It also indicates that there is a conflict between improving throughput and decreasing interference, and the proposed algorithm can make better use of spectrum by balancing the conflict. |
| Author(s): | X. Liu, X. Tan |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 442 KB |
| Title: | Accelerating the Multilevel Fast Multipole Method with Parallel Preconditioner for Large-Scale Scattering Problems |
| Abstract: | A novel parallel framework is proposed for the iterative solution of the multilevel fast multipole method (MLFMM). The inversion of the near-field impedance matrix is used as the preconditioner matrix to improve the convergence history of the ill-conditioned linear system formulated by electric field integral equation. In order to accelerate the inversion of the near field impedance matrix with huge number of unknowns, the parallel technique is used to construct the preconditioner matrix. Our numerical experiments reveal that with an efficiently parallelized MLFMM and the effective parallel preconditioner, we are able to solve problems with millions of unknowns in a few hours. Both the number of iteration steps and the overall simulation time can be saved significantly. For closed-surface problems analyzed by the combined-field integral equation, the number of iterations can also be reduced significantly by the proposed method. Numerical results are presented to demonstrate the accuracy and efficiency of the proposed method. |
| Author(s): | M. Chen, R. Chen, Z. Fan, D. Ding |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 327 KB |
| Title: | Cosecant Squared Pattern Synthesis for Reflector Antenna using a Stochastic Method |
| Abstract: | A novel method based on invasive weed optimization (IWO) algorithm is described for synthesizing a point source doubly curved reflector antenna to produce a shaped beam in one plane and narrow beam in the perpendicular plane. The whole reflector body can be created by determining two basic curves. The central vertical curve is approximately responsible for producing a shaped beam in the vertical plane. It can be expressed by a well-defined function, and the function coefficients will compose a solution space to be explored by IWO. The transverse section curve is known to be a parabola for producing a narrow beam in that plane. The validity of the proposed method is verified by an example of shaped reflector antenna with cosecant squared pattern and comparing it with previously used methods. The simulation results based on physical optics (PO) further prove the validity and versatility of this technique for solving reflector synthesize problems. |
| Author(s): | A. R. Mallahzadeh, P. Taghikhani |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 602 KB |
| Title: | An Efficient Parallel FE-BI Algorithm for Large-scale Scattering Problems |
| Abstract: | In this paper, we present fast and accurate solutions of large-scale scattering problems involving three-dimensional objects with arbitrary shapes using parallel finite elementboundary integral method (FE-BI). Particularly, an efficient parallel preconditioner is constructed with both the finite-element matrix and the nearfield part of the boundary integral equation operator for the ill-conditioned linear system formulated by the FE-BI. With an efficient parallelization of FE-BI, scattering problems that are discretized with millions of unknowns could be easily solved on distributed-memory computers. The numerical results are presented to demonstrate the accuracy and efficiency of the proposed method. |
| Author(s): | Z. H. Fan, M. Chen, R. S. Chen, D. Z. Ding |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 390 KB |
| Title: | Improving the Convergence of the Wave Iterative Method by Filtering Techniques |
| Abstract: | Among the numerical methods used in the electromagnetic modeling of high frequency electronic circuits, we include the wave concept iterative method. In this paper, we propose to improve the convergence speed of this method when modeling a complex structure. This method requires a maximum number of iterations, noted “Nmax”, to achieve the convergence to the optimal value. Our goal is to reduce the number of iterations calculated by this method to the value “Nmin” in order to reduce the computing time and to improve the convergence speed. This is done by adding a new algorithm based on filtering techniques. |
| Author(s): | H. Hrizi, L. Latrach, N. Sboui, A. Gharsallah, A. Gharbi, H. Baudrand |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 226 KB |
| Title: | Perforated Dielectric Resonator Antenna Reflectarray |
| Abstract: | A wideband perforated rectangular dielectric resonator antenna (RDRA) reflectarray is presented. The arrays of RDRA are formed from one piece of materials. Air-filled holes are drilled into the material around the RDRA. This technique of fabricating RDRA reflectarray using perforations eliminates the need to position and bond individual elements in the reflectarray and makes the fabrication of the RDRA reflectarray feasible. The ground plane below the reflectarray elements is folded as a rectangular concave surface so that an air-gap is formed between the RDRA elements and the ground plane in order to increase the bandwidth. Full-wave analysis using the finite integration technique is applied. Three cases are studied. In the first one, the horn antenna is placed at the focal point to illuminate the reflectarray and the main beam in the broadside direction. In the second one, the horn antenna is placed at the focal point and the main beam at ±30 degrees off broadside direction. In the third one, an offset feed RDRA reflectarray is considered. A variable length RDRA provides the required phase shift at each cell on the reflectarray surface. The normalized gain patterns, the frequency bandwidth, and the aperture efficiency for the above cases are calculated. |
| Author(s): | S. H. Zainud-Deen, S. M. Gaber, A. M. Abd-Elhady, K. H. Awadalla, A. A. Kishk |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 733 KB |
| Title: | Design of a Planar UWB Antenna with New Band Enhancement Technique |
| Abstract: | A planar antenna and a technique for enhancing its bandwidth for UWB applications have been proposed in this paper. The proposed antenna which has a compact structure and the total size of 30 × 22 mm2 consists of a square patch and a partial ground plane. Numerical study shows that the bandwidth of the proposed antenna can be controlled mainly by the patch size and width of the feeding line. The cutting triangular shape slots on the top edge of the ground plane help to increase the bandwidth by 43.6% (3.89 GHz). The measured -10 dB return loss bandwidth of the proposed antenna ranges from 2.95 GHz to 15.45 GHz which covers the entire UWB band. The nearly stable radiation pattern with a maximum gain of 5.9 dBi makes the proposed antenna suitable for being used in UWB communication. |
| Author(s): | R. Azim, M. T. Islam, N. Misran |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 386 KB |
| Title: | A Novel UWB Out-of-Phase Four-Way Power Divider |
| Abstract: | A novel ultra-wideband (UWB) out-ofphase four-way power divider is presented. To achieve a division over a large frequency range, Tjunctions formed by slotlines and microstrip lines are utilized. Based on the transmission-line equivalent-circuit method, we derive the design equations of the proposed power divider. Furthermore, all measured results are in good agreement with the predicted design equations and simulations. In addition, based on the power divider, a completely novel feed network is proposed to improve the narrow band property of microstrip antenna array. |
| Author(s): | B. Xiao, J. Hong, B. Wang |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1793 KB |
| Title: | Fundamental and Magnetic Force Analysis of an External Rotor Switched Reluctance Motor |
| Abstract: | This paper presents a novel three-phase 6/8 external rotor switched reluctance motor. Such a construction not only leads to reduce the total weight and volume, but also increases the total efficiency in a small size motor. Three dimensional finite element method is applied to evaluate the main characteristics of the proposed motor such as magnetic flux density, flux linkage, self-inductance, mutual inductance, and output torque. Moreover, this paper investigates the radial force components of the motor. This assessment is carried out under different forced current levels with the respect to critical rotor positions. From the motor analysis results, it is considered that the proposed motor has great advantages over the conventional type in its magnetic profiles. |
| Author(s): | H. Torkaman, N. Arbab, H. Karim, E. Afjei |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 10 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 663 KB |