Showing papers by "University of Electronic Science and Technology of China published in 2005"
TL;DR: The state-of-the-art positioning designs are surveyed, focusing specifically on signal processing techniques in network-aided positioning, to provide new directions for future research.
Abstract: Wireless positioning has attracted much research attention and has become increasingly important in recent years. Wireless positioning has been found very useful for other applications besides E911 service, ranging from vehicle navigation and network optimization to resource management and automated billing. Although many positioning devices and services are currently available, it is necessary to develop an integrated and seamless positioning platform to provide a uniform solution for different network configurations. This article surveys the state-of-the-art positioning designs, focusing specifically on signal processing techniques in network-aided positioning. It serves as a tutorial for researchers and engineers interested in this rapidly growing field. It also provides new directions for future research for those who have been working in this field for many years.
604 citations
TL;DR: In this paper, a novel approach to realize uniform amplitude time modulated linear arrays with both suppressed sidelobes and sidebands is proposed, which utilizes the direct optimization of the "switch-on" time sequence of each array element via the simple genetic algorithm (SGA).
Abstract: A novel approach to realize uniform amplitude time modulated linear arrays with both suppressed sidelobes and sidebands is proposed. The approach utilizes the direct optimization of the "switch-on" time sequence of each array element via the simple genetic algorithm (SGA). As compared to previous time modulated linear arrays, the new array has the advantages of having low sidelobe level (SLL), low sideband level (SBL) and uniform excitations simultaneously. Experimental results on an experimental prototype of a 16-element printed dipole linear array with the SGA optimized time sequences verified the approach.
247 citations
TL;DR: In this article, composite films of multi-walled carbon nanotubes (MWNTs) and polyaniline (PAn) were grown electrochemically from acidic aqueous solutions, such that the constituents were deposited simultaneously onto graphite electrodes.
Abstract: Nanoporous composite films of multi-walled carbon nanotubes (MWNTs) and polyaniline (PAn) were grown electrochemically from acidic aqueous solutions, such that the constituents were deposited simultaneously onto graphite electrodes. Scanning electron microscopy (SEM) revealed that the composite films consisted of nanoporous networks of MWNTs coated with PAn. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that these composite films had similar electrochemical response rates to pure PAn films, but a lower resistance and much improved mechanical integrity. The specific electrochemical capacitance of the composite films, per unit area of the original electrode, reached as high as 3.5 F cm−2, a significantly greater value than that of 2.3 F cm−2 for pure PAn films prepared similarly.
161 citations
TL;DR: The results confirm that different choices of reference electrodes result in systematic changes in the distribution of EEG frequency power, and in order to reduce the effect of such systematic shifts on the explanation of EEG mappings, a common reference is necessary for EEG research.
Abstract: Based on EEG data recorded from 11 subjects with eyes open and the left mastoid (M) reference, three data sets were generated by re-referencing to the conventional linked mastoids (L), average (A) and the new 'infinity' (I) reference provided by the reference electrode standardization technique (REST, Yao 2001 Physiol. Meas. 22 693–711). The EEG power in the alpha frequency band with the four different references was calculated and compared with respect to the total energy and spatial amplitude weight centre (AWC) coordinates, to compare the effects of different references on power mapping in the frequency domain. Compared with the I reference, the AWCs of the EEG with the M reference show significant shifts to the right, frontal and superficial positions, the L reference significant shifts to frontal and superficial positions, and the A reference shifts the AWC significantly to a deeper position. Furthermore, the power maps of the M and L references have larger total power than the I reference, while that of the A reference has the smallest total power. These results confirm that different choices of reference electrodes result in systematic changes in the distribution of EEG frequency power, and in order to reduce the effect of such systematic shifts on the explanation of EEG mappings, a common reference is necessary for EEG research. We recommend the I reference for objective use in cross-laboratory studies and clinical practices, as it is far from all the other electrodes and can act as a neutral reference.
157 citations
Journal Article•
TL;DR: In this paper, both pure and Al doped ZnO thin films were fabricated on glass substrates by sol-gel method, and it was found that all the thin films have a preferential c-axis orientation.
Abstract: Pure and Al doped ZnO thin films were fabricated on glass substrates by sol-gel method. It is found that all the thin films have a preferential c-axis orientation. With increase of Al doping, the peak position of the (002) plane is shifted to the low 2θ value. A minimum resistivity of 6.2×10~(-4) Ω·cm is obtained for the film doped with 1.5 % Al. However, the resistivity increases with increasing Al concentration. The bandgap is found to broaden with increasing dopant concentration, and it is found that doping with Al has the effect of shifting the optical absorption to the shorter wavelength, which both cases are attributed to the Burstein-Moss shift.
155 citations
27 Aug 2005
TL;DR: A novel algorithm of document clustering based on non-negative sparse analysis that can obtain documents topics exactly by controlling the sparseness of the topic matrix and the encoding matrix explicitly is proposed.
Abstract: A novel algorithm of document clustering based on non-negative sparse analysis is proposed. In contrast to the algorithm based on non-negative matrix factorization, our algorithm can obtain documents topics exactly by controlling the sparseness of the topic matrix and the encoding matrix explicitly. Thus, the clustering accuracy has been improved greatly. In the end, simulation results are employed to further illustrate the accuracy and efficiency of this algorithm.
137 citations
TL;DR: In this article, a data mining based electricity price forecast framework is proposed, which can predict the normal price as well as the price spikes. But the model is tested with the Queensland electricity market data with promising results.
131 citations
TL;DR: It is suggested that the introduced PSO algorithm could act as a new promising solution to the beam angle optimization problem and potentially other optimization problems in IMRT, though further studies need to be investigated.
Abstract: Automatic beam angle selection is an important but challenging problem for intensity-modulated radiation therapy (IMRT) planning. Though many efforts have been made, it is still not very satisfactory in clinical IMRT practice because of overextensive computation of the inverse problem. In this paper, a new technique named BASPSO (Beam Angle Selection with a Particle Swarm Optimization algorithm) is presented to improve the efficiency of the beam angle optimization problem. Originally developed as a tool for simulating social behaviour, the particle swarm optimization (PSO) algorithm is a relatively new population-based evolutionary optimization technique first introduced by Kennedy and Eberhart in 1995. In the proposed BASPSO, the beam angles are optimized using PSO by treating each beam configuration as a particle (individual), and the beam intensity maps for each beam configuration are optimized using the conjugate gradient (CG) algorithm. These two optimization processes are implemented iteratively. The performance of each individual is evaluated by a fitness value calculated with a physical objective function. A population of these individuals is evolved by cooperation and competition among the individuals themselves through generations. The optimization results of a simulated case with known optimal beam angles and two clinical cases (a prostate case and a head-and-neck case) show that PSO is valid and efficient and can speed up the beam angle optimization process. Furthermore, the performance comparisons based on the preliminary results indicate that, as a whole, the PSO-based algorithm seems to outperform, or at least compete with, the GA-based algorithm in computation time and robustness. In conclusion, the reported work suggested that the introduced PSO algorithm could act as a new promising solution to the beam angle optimization problem and potentially other optimization problems in IMRT, though further studies need to be investigated.
113 citations
TL;DR: An evolving network model is proposed which exhibits community structure based on the inner-community preferential attachment and inter- community preferential attachment mechanisms and the degree distributions are analysed based on a mean-field method.
Abstract: Many social and biological networks consist of communities—groups of nodes within which connections are dense, but between which connections are sparser. Recently, there has been considerable interest in designing algorithms for detecting community structures in real-world complex networks. In this paper, we propose an evolving network model which exhibits community structure. The network model is based on the inner-community preferential attachment and inter-community preferential attachment mechanisms. The degree distributions of this network model are analysed based on a mean-field method. Theoretical results and numerical simulations indicate that this network model has community structure and scale-free properties.
101 citations
TL;DR: The fuzzy controllers for hyperchaotic synchronization are designed via the exact linearization techniques, based on the T–S fuzzyHyperchaotic systems, which are exactly derived from the fuzzy model-based designs.
Abstract: This paper presents fuzzy model-based designs for synchronization of hyperchaotic systems. The T–S fuzzy models for hyperchaotic systems are exactly derived. Based on the T–S fuzzy hyperchaotic models, the fuzzy controllers for hyperchaotic synchronization are designed via the exact linearization techniques. Numerical examples are given to demonstrate the effectiveness of the proposed method.
95 citations
TL;DR: Proton irradiation at temperatures of 310 and 350°C has been explored as a method of studying radiation effects in Zircaloy 4 under power-reactor conditions as mentioned in this paper The dislocation-loop and hardness evolution are similar to those observed under neutron irradiation Amorphization and Fe loss at Zr(Cr,Fe)2 precipitates are observed Energy-filtered images indicate Fe accumulation in the matrix near the precipitate.
Abstract: Proton irradiation at temperatures of 310 and 350°C has been explored as a method of studying radiation effects in Zircaloy 4 under power-reactor conditions The dislocation-loop and hardness evolution are similar to those observed under neutron irradiation Amorphization and Fe loss at Zr(Cr,Fe)2 precipitates are observed Energy-filtered images indicate Fe accumulation in the matrix near the precipitate, a phenomenon not reported in neutron-irradiated alloys
TL;DR: In this article, the theoretical and experimental studies of linear antenna arrays with bidirectional phase center motion (BPCM) are presented, where the sidelobes of the linear arrays with BPCM experience both upper and lower Doppler frequency shift effect in turn.
Abstract: The theoretical and experimental studies of linear antenna arrays with bidirectional phase center motion (BPCM) is presented. BPCM is achieved by exciting only part of the linear array elements and sweeping the excited part from one end to the other and back. The sidelobes of the linear arrays with BPCM experience both upper and lower Doppler frequency shift effect in turn, as compared to linear arrays with unidirectional phase center motion (UPCM). Numerical results show that linear arrays with BPCM are also capable of synthesizing low/ultralow sidelobes, but with a much lower excitation dynamic range ratio as compared to that in conventional arrays. In addition, some characteristics, such as passband bandwidth or sideband levels, are better than those of arrays with UPCM or time modulated variable aperture size arrays. An L-band 16-element printed dipole linear array with BPCM was designed. Experimental results show that a -35 dB relative sidelobe level (SLL) can be achieved.
TL;DR: In this article, the a-and c-axis lattice constants of BaxSr1−xTiO3 ceramics were calculated and it was found that the crystal structures are tetragonal phase when x ≥ 0.65 at room temperature.
Abstract: The crystalline structure and dielectric properties of BaxSr1−xTiO3 ceramics with x = 0.45, 0.5, 0.6, 0.65, 0.8, 0.9 were investigated. The a- and c-axis lattice constants of BaxSr1−xTiO3 ceramics were calculated and it is found that the crystal structures are tetragonal phase when x ≥ 0.65 at room temperature. The Curie–Weiss temperature (T0) is always lower than Curie temperature (TC) and the linear relation between the Curie temperature and the stoichiometric percentage of barium can be observed and expressed as TC (°C) = −195.0 + 322.2x. The values of coercive electric field (EC) and remanent polarization (Pr) increase as Ba/Sr ratio of BaxSr1−xTiO3 ceramics increases except for x ≤ 0.5, which are due to the decrease in grain size and the difference between the radius of Ba2+ and that of Sr2+.
TL;DR: The results illustrate that IIMOM is effective in capturing different kinds of preference structures of the designer, and it provides a complete and effective solution for medium- and small-scale multiobjective optimization problems.
Abstract: In most practical situations involving reliability optimization, there are several mutually conflicting goals such as maximizing the system reliability and minimizing the cost, weight and volume. This paper develops an effective multiobjective optimization method, the Intelligent Interactive Multiobjective Optimization Method (IIMOM). In IIMOM, the general concept of the model parameter vector is proposed. From a practical point of view, a designer's preference structure model is built using Artificial Neural Networks (ANNs) with the model parameter vector as the input and the preference information articulated by the designer over representative samples from the Pareto frontier as the desired output. Then with the ANN model of the designer's preference structure as the objective, an optimization problem is solved to search for improved solutions and guide the interactive optimization process intelligently. IIMOM is applied to the reliability optimization problem of a multi-stage mixed system with five di...
TL;DR: A novel fingerprint matching algorithm is developed using both the orientation field and minutia to identify corresponding minutiae between two fingerprint impressions by computing the Euclidean distance between vectors.
TL;DR: In this article, a two-step mechanical alloying (MA) process was used to obtain nanocrystalline FeNi alloy powders with different particle size. But, it is observed and discussed that microwave complex permeability is prominently affected by FeNi microstructure and particle size, and this value may be useful for thin-thickness and wide-band microwave absorber.
TL;DR: It is shown that fractional-order chaotic oscillators can be synchronized with appropriate coupling strength with numerically demonstrated using the master–slave synchronization scheme.
Abstract: The dynamics of fractional-order systems have attracted increasing attentions in recent years. In this paper, the synchronization of two coupled nonlinear fractional order chaotic oscillators is numerically demonstrated using the master–slave synchronization scheme. It is shown that fractional-order chaotic oscillators can be synchronized with appropriate coupling strength.
TL;DR: In this paper, a new BPSOI (buried layer partial SOI) structure is developed, in which the P-type buried layer is implanted into the P− substrate by silicon window underneath the source of the conventional PSOI.
Abstract: A new BPSOI (buried layer partial SOI) structure is developed, in which the P-type buried layer is implanted into the P− substrate by silicon window underneath the source of the conventional PSOI. The mechanism of breakdown is that the additional electric field produced by P-type buried layer charges modulates surface electric field, which decreases drastically the electric field peaks near the drain and source junctions. Moreover, the on-resistance of BPSOI is decreased as a result of increasing drift region doping due to neutralism of P-type buried layer. The results indicate that the breakdown voltage of BPSOI is increased by 52–58% and the on-resistance is decreased by 45–48% in comparison to conventional PSOI in virtue of 2-D numerical simulations using MEDICI.
TL;DR: In this paper, a systematic investigation of hydrogen on Ru(0 0 1) surface has been carried out by means of periodic DFT calculations, and the calculated vibrational frequencies of 1109 and 785 cm(-1) for H adsorbed in (root 3 x root 3)R30 degrees were attributed to perpendicular and doubly degenerated parallel vibrations of H atoms.
TL;DR: define a novel feature vector for each fingerprint minutia based on the global orientation field that is used to identify corresponding minutiae between two fingerprint impressions by computing the Euclidean distance between vectors.
TL;DR: In this article, the effect of oxygen plasma treatment on the surface properties of indium-tin oxide (ITO) anodes and the changes in surface properties with aging time were investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photo-electron (UPS) measurements, and the aging effect of treated ITO anodes was studied with respect to the driving voltage, electroluminescent luminance and efficiency.
23 Aug 2005
TL;DR: A new algorithm for efficient generating large frequent candidate sets is proposed, which is called Matrix Algorithm, which generates a matrix which entries 1 or 0 by passing over the cruel database only once, and then the frequent Candidate sets are obtained from the resulting matrix.
Abstract: Finding association rules is an important data mining problem and can be derived based on mining large frequent candidate sets. In this paper, a new algorithm for efficient generating large frequent candidate sets is proposed, which is called Matrix Algorithm. The algorithm generates a matrix which entries 1 or 0 by passing over the cruel database only once, and then the frequent candidate sets are obtained from the resulting matrix. Finally association rules are mined from the frequent candidate sets. Numerical experiments and comparison with the Apriori Algorithm are made on 4 randomly generated test problems with small, middle and large sizes. Experiments results confirm that the proposed algorithm is more effective than Apriori Algorithm.
TL;DR: The robust stability of neural networks with time-varying delay and time- varying parametric uncertainties is considered and the stability condition is given in terms of linear matrix inequality (LMI).
Abstract: The robust stability of neural networks with time-varying delay and time-varying parametric uncertainties is considered. The stability condition is given in terms of linear matrix inequality (LMI). Numerical example is presented to demonstrate the effectiveness of our theoretical results.
TL;DR: In this paper, the effect of heating and cooling rate on the transformation characteristics in TiNiCu shape memory alloy were investigated by differential scanning calorimetry (DSC), and the results showed that the martensitic end transformation temperature (Mf) and reverse end transformation (Af) depend strongly on the scanning rate of the heating-cooling process, Mf decreased and Af increased with increasing cooling/heating rate.
TL;DR: In this paper, the stability problem of uncertain systems with arbitrarily time-varying delay is considered, and stability conditions are proposed for such systems in terms of linear matrix inequalities (LMIs).
Abstract: In this paper, the stability problem of uncertain systems with arbitrarily time-varying delay is considered. Based on new Lyapunov–Krasovskii functionals and novel methods to deal with uncertainties and cross-terms, stability conditions are proposed for such systems in terms of linear matrix inequalities (LMIs), which are simpler and less conservative than existing results. A numerical example is given to illustrate our theoretical result.
TL;DR: In this article, the effect of Yb/Mg co-doping on the microstructure and electrical properties of BaTiO 3 ceramics sintered under oxidizing, reducing and annealed conditions was investigated.
TL;DR: In this article, an interactive physical programming approach is developed to place physical programming into an interactive framework in a natural way, and an optimal solution that satisfies the designer's preferences is supposed to be obtained by the end of the procedure.
Abstract: The preliminary design optimization of multi-stage spur gear reduction units has been a subject of considerable interest, since many high-performance power transmission applications (e.g., automotive and aerospace) require high-performance gear reduction units. There are multiple objectives in the optimal design of multi-stage spur gear reduction unit, such as minimizing the volume and maximizing the surface fatigue life. It is reasonable to formulate the design of spur gear reduction unit as a multi-objective optimization problem, and find an appropriate approach to solve it. In this paper an interactive physical programming approach is developed to place physical programming into an interactive framework in a natural way. Class functions, which are used to represent the designer’s preferences on design objectives, are fixed during the interactive physical programming procedure. After a Pareto solution is generated, a preference offset is added into the class function of each objective based on whether the designer would like to improve this objective or sacrifice the objective so as to improve other objectives. The preference offsets are adjusted during the interactive physical programming procedure, and an optimal solution that satisfies the designer’s preferences is supposed to be obtained by the end of the procedure. An optimization problem of three-stage spur gear reduction unit is given to illustrate the effectiveness of the proposed approach.
TL;DR: It is proved that there exist computer viruses with arbitrarily long running time, not only in the infecting procedure but in the executing procedure, and there are undecidable computer viruses that have no "minimal" detecting procedure.
Abstract: Computer viruses can disable computer systems not only by destroying data or modifying a system's configuration, but also by consuming most of the computing resources such as CPU time and storage. The latter effects are related to the computational complexity of computer viruses. In this correspondence, we investigate some issues concerning the time complexity of computer viruses, and prove some known experimental results mathematically. We prove that there exist computer viruses with arbitrarily long running time, not only in the infecting procedure but in the executing procedure. Moreover, we prove that there are computer viruses with arbitrarily large time complexity in the detecting procedure, and there are undecidable computer viruses that have no "minimal" detecting procedure.
TL;DR: In this article, a practical approach to compensate for the mutual coupling effect in low sidelobe time modulated linear antenna arrays is proposed, taking into account the measured complex embedded element patterns, the compensated element weights and time sequences are optimized by the differential evolution (DE) algorithm.
Abstract: A practical approach to compensate for the mutual coupling effect in low sidelobe time modulated linear antenna arrays is proposed. Taking into account the measured complex embedded element patterns, the compensated element weights and time sequences are optimized by the differential evolution (DE) algorithm. The proposed approach is experimentally verified by the successful realization of a -30 dB sidelobe level discrete Taylor pattern from a 16-element time modulated linear array. Numerical results are compared with measured data and good agreement is reported.