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2007
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| |  | Tang, A. | Equilibrium of Heterogeneous Congestion Control: Existence and Uniqueness read moreAbstract: When heterogeneous congestion control protocols that react to different pricing signals share the same network, the resulting equilibrium may no longer be interpreted as a solution to the standard utility maximization problem. We prove the existence of equilibrium in general multiprotocol networks under mild assumptions. For almost all networks, the equilibria are locally unique, finite, and odd in number. They cannot all be locally stable unless there is a globally unique equilibrium. Finally, we show that if the price mapping functions, which map link prices to effective prices observed by the sources, are sufficiently similar, then global uniqueness is guaranteed.  This article is not yet tagged | 2007 |
| | | Shen, M. | Comparison of Traditional Inverters and <formula><tex>$Z$</tex> </formula>-Source Inverter for Fuel Cell Vehicles read moreAbstract: In this paper, three different inverters: conventional pulsewidth modulation (PWM) inverter, dc–dc boosted PWM inverter, and $Z$ -source inverter were investigated and compared for fuel cell vehicle application. Total switching device power, passive components requirement, and constant power speed ratio of each of these inverters were calculated. For purposes of comparison, an example of the total switching device power, requirement of passive components, the constant power speed ratio, and the efficiencies of the different inverters for fuel cell vehicle powered by the same fuel cell were conducted. The comparisons show that the $Z$ -source inverter is very promising in applications when the boost ratio is low (1–2). This article is not yet tagged | 2007 |
| | | Cao, C. | Intelligent Excitation for Adaptive Control With Unknown Parameters in Reference Input read moreAbstract: Model reference adaptive control problem is considered for a class of reference inputs dependent upon the unknown parameters of the system. Due to the uncertainty in the reference input, the tracking objective cannot be achieved without parameter convergence. The common approach of injecting persistent excitation (PE) in the reference input leads to tracking of the excited reference input as opposed to the true one. A new technique, named intelligent excitation, is presented for introducing an excitation signal in the reference input and regulating its amplitude, dependent upon the convergence of the output tracking and parameter errors. Intelligent excitation ensures parameter convergence, similar to conventional PE; it vanishes as the errors converge to zero and reinitiates with every change in the unknown parameters. As a result, the regulated output tracks the desired reference input and not the excited one. This article is not yet tagged | 2007 |
| | | Yan, P. | Experimental investigation of surface flashover in vacuum using nanosecond pulses read moreAbstract: Sorry no abstract available for this article This article is not yet tagged | 2007 |
| | | Liu, Z. | Development of High-Voltage Vacuum Circuit Breakers in China read moreAbstract: This paper introduces a research work on the development of high-voltage (HV) vacuum circuit breakers (VCBs) in China from its start point 1989 to 2006. In this period, a 126-kV two breaks VCB prototype and a 126-kV single break VCB prototype were developed. A latest 252-kV single break interrupter prototype is introduced. Five HV VCBs technologies are discussed, which include HV vacuum insulation, high current interrupting technology with long contact gaps, increasing nominal current, operating mechanism characteristics, and contact bouncing damping. In vacuum insulation, adding a metal ring at electrode back can decrease breakdown possibilities in the gap between the electrode back and main shield. Surface melting layer of contact material could have influence on voltage withstanding capability of a vacuum gap. For interrupting high current with long contact gaps, strong axial magnetic field (AMF) is needed for a better vacuum arc control. Therefore, a single coil AMF electrode is introduced. Heat radiators are effective to increase nominal current of VCBs. Thermal analysis can help to give appropriate design parameters. There is an optimum opening characteristic that is helpful to improve the interrupting performance of VCBs. Permanent magnet operating mechanism and spring-type operating mechanism are suitable for HV VCBs. Contact bouncing in HV VCBs can be damped by installing contact spring and bellows on stationary end of VCBs. This article is not yet tagged | 2007 |
| | | Mei, X. B. | 35-nm InP HEMT SMMIC Amplifier With 4.4-dB Gain at 308 GHz read moreAbstract: We report the first submillimeter-wave monolithic microwave integrated circuit (MMIC) amplifier with 4.4-dB measured gain at 308-GHz frequency, making it the highest frequency MMIC amplifier reported to date. In this letter, a 35-nm InP high-electron mobility transistor process has been successfully developed with a projected maximum available gain of greater than 7 dB at 300 GHz. The excellent dc and RF performance makes it suitable for applications at frequencies well into the millimeter-wave band and, for the first time, in the submillimeter-wave band as well. This article is not yet tagged | 2007 |
| | | Hao, J. | Nonlinear Decentralized Disturbance Attenuation Excitation Control for Power Systems With Nonlinear Loads Based on the Hamiltonian Theory read moreAbstract: A novel nonlinear control scheme for disturbance attenuation of structure preserving multimachine power systems based on Hamiltonian theory is proposed in this paper. The proposed control scheme includes two steps: first, the dissipative Hamiltonian realization of structure preserving power system is completed using the singular perturbation approach in which the algebraic equations are considered as a limit of fast dynamics; second, a nonlinear decentralized disturbance attenuation excitation controller is designed without linearization to improve transient stability of power system as well as the robustness with respect to unknown exogenous disturbance in the sense of $L_2$-gain. Simulation on a two-area system demonstrates that the proposed scheme can enhance transient stability of the system regardless of the exogenous disturbance. This article is not yet tagged | 2007 |
| | | Zheng, P. | Optimization of the Magnetic Pole Shape of a Permanent-Magnet Synchronous Motor read moreAbstract: A kind of six-slot/four-pole permanent-magnet (PM) synchronous motor is very popular nowadays for the advantages of saving coppers and because it is easy to manufacture. The magnetomotive force (MMF) produced by the six-slot stator windings are not symmetrical under the four poles, and more harmonics exist in the air gap, which will increase the torque ripple and noise. In this paper the rotor structure is optimized from the aspects of magnetic-pole embrace, magnetic bridge, and magnetic-pole eccentricity to obtain better air-gap magnetic field distribution and torque curves. This article is not yet tagged | 2007 |
| | | Song, S. | Finite Element Analysis of Alternating Write-Current-Induced Pole Tip Protrusion in Magnetic Recording Heads read moreAbstract: This paper presents a finite element analysis of alternating write-current-induced pole tip protrusion (WPTP) generated in longitudinal magnetic recording (LMR) heads. An integrated magneto-thermal-mechanical model is developed for the simulations of the electromagnetic Joule heating generated in the LMR writer, the slider temperature distribution, and the slider deformation during writing. The computed results are compared with the experimental measurements in terms of writer resistance and inductance, the WPTP, and temperature rise at reader location. It is found that eddy currents are strongly induced near the surfaces of write poles, while the eddy currents induced in write coils are negligibly weak. The results show that the eddy current loss in the write poles dominates over the Joule heat generated in the write coils. It is also found that the maximum protrusion appears near the write pole in the overcoat and the protrusion profile is sharper than that induced by equivalent direct write current and coil resistance. This article is not yet tagged | 2007 |
| | | Yoon, S. D. | Ferrite-Coupled Line Circulator Simulations For Application at X-Band Frequency read moreAbstract: We have designed and simulated a circulator circuit in which the magnetization aligns along the plane of an yttrium iron garnet (YIG) film. For an X-band frequency (8–12 GHz) circulator we have utilized a YIG slab ($sim$200 $mu$m thick) with saturation magnetization $(4pi{M}_{S})$ and ferrimagnetic resonance (FMR) linewidth $(Delta {H})$ of $sim $139.26 kA/m and 10 Oe, respectively. Broadband circulator operation was realized for frequencies above FMR, $f=5$ GHz. The applied FMR field was 79.58 kA/m. The Ansoft HFSS software suite was used to simulate the circulator response. The insertion loss ${S}_{21}$ and the isolation ${S}_{12}$ were calculated to be $sim $0.9 dB and $sim {-}$52 dB, respectively, with $sim $15% bandwidth at the center frequency of 10.1 GHz. We believe that this in-plane circulator design may enable high performance with significant volume and weight reduction. This article is not yet tagged | 2007 |
| | | Hu, X. | A Recurrent Neural Network for Solving a Class of General Variational Inequalities read moreAbstract: This paper presents a recurrent neural-network model for solving a special class of general variational inequalities (GVIs), which includes classical VIs as special cases. It is proved that the proposed neural network (NN) for solving this class of GVIs can be globally convergent, globally asymptotically stable, and globally exponentially stable under different conditions. The proposed NN can be viewed as a modified version of the general projection NN existing in the literature. Several numerical examples are provided to demonstrate the effectiveness and performance of the proposed NN This article is not yet tagged | 2007 |
| | | Yang, J. -. | Optimization Models for Training Belief-Rule-Based Systems read moreAbstract: A belief Rule-base Inference Methodology using the Evidential Reasoning approach (RIMER) has been developed recently, where a new belief rule representation scheme is proposed to extend traditional IF–THEN rules. The belief rule expression matrix in RIMER provides a compact framework for representing expert knowledge. However, it is difficult to accurately determine the parameters of a belief rule base (BRB) entirely subjectively, particularly, for a large-scale BRB with hundreds or even thousands of rules. In addition, a change in rule weight or attribute weight may lead to changes in the performance of a BRB. As such, there is a need to develop a supporting mechanism that can be used to train, in a locally optimal way, a BRB that is initially built using expert knowledge. In this paper, several new optimization models for locally training a BRB are developed. The new models are either single- or multiple-objective nonlinear optimization problems. The main feature of these new models is that only partial input and output information is required, which can be either incomplete or vague, either numerical or judgmental, or mixed. The models can be used to fine tune a BRB whose internal structure is initially decided by experts' domain-specific knowledge or common sense judgments. As such, a wide range of knowledge representation schemes can be handled, thereby facilitating the construction of various types of BRB systems. Conclusions drawn from such a trained BRB with partially built-in expert knowledge can simulate real situations in a meaningful, consistent, and locally optimal way. A numerical study for a hierarchical rule base is examined to demonstrate how the new models can be implemented as well as their potential applications. This article is not yet tagged | 2007 |
| | | Nie, Y. | Synergy Study for Plasma-Facilitated <formula formulatype="inline"><tex>$hbox{C}_{2} hbox{H}_{4}$</tex></formula> Selective Catalytic Reduction of <formula formulatype="inline"><tex>$hbox{NO}_{x}$ </tex></formula> Over <formula formulatype="inline"><tex>$ read moreAbstract: Synergy study is of great importance to optimize the two-stage plasma-facilitated catalysis system and also necessary to gain a mechanistic understanding of the overall reaction process. In this paper, the effects of the long-lived chemical products of plasma pretreatment on the subsequent selective catalytic reduction (SCR) of $hbox{NO}_{x}$ at fixed and changed energy density of dielectric-barrier-discharge plasma reactor were investigated, respectively, for the aim of the synergy study of plasma-facilitated $hbox{C}_{2}hbox{H}_{4}$-SCR (PF-SCR) of $hbox{NO}_{x}$ over $ hbox{Ag}/gammahbox{-}hbox{Al}_{2}hbox{O}_{3}$ catalyst at lower temperature. For comparison, $hbox{C}_{2}hbox{H}_{4}$-SCR of $hbox{NO}_{x}$ over $hbox{Ag}/gammahbox{-}hbox{Al}_{2} hbox{O}_{3}$ catalyst alone was also considered. Results showed that PF-SCR for $hbox{NO}_{x}$ removal exhibited obvious synergistic effect at 240 $^{circ}hbox{C}$, and the $hbox{NO}_{x}$ removal efficiency for plasma alone, $ hbox{C}_{2}hbox{H}_{4}$-SCR alone, and PF-SCR were 43.6%, 6.7%, and 90.1%, respectively. In the $hbox{NO}/hbox{NO}_{2}/hbox{C}_{2}hbox{H}_{4}/hbox{O}_{2}/hbox{N}_{2}$ system, the long-lived chemical products of plasma pretreatment for the synergistic link between plasma and catalysis included $hbox{NO}_{2}$, a-
ldehyde (formaldehyde and acetaldehyde), and nitrogen-contained organic compounds (methyl nitrate, nitro methyl, and ethyl nitrate). Among the nitrogen-contained chemical products of plasma pretreatment, the major synergistic link between plasma and catalysis was $hbox{NO}_{2}$ at lower input energy density, transferred to the mutual action of $hbox{NO}_{2}$ and nitrogen-contained organic compounds over catalyst at higher input energy density. This article is not yet tagged | 2007 |
| | | Mangan, S. | Development of a Novel Sensorless Longitudinal Road Gradient Estimation Method Based on Vehicle CAN Bus Data read moreAbstract: The availability of road gradient information will have a big impact upon the quality of vehicle control. This paper presents a novel “sensorless” longitudinal road-gradient estimation method, which was developed in two steps starting from a benchmark system design. The gradient benchmark system consists of an inclinometer sensor and an acceleration-based error correction algorithm, which can be used to verify the accuracy of the road gradient obtained using a sensorless estimation method. The sensorless road-gradient estimation algorithm uses the vehicle data currently available on the vehicle controller area network (CAN) bus. The completed gradient estimation algorithm was successfully tested online in variable road conditions and different driving manners. The test results showed that the resulting longitudinal road-gradient estimation algorithm fulfilled the specified accuracy requirement, and provided a cost effective and reliable way for longitudinal road-gradient estimation in real time. This article is not yet tagged | 2007 |
| | | Wang, J. | Robust Inventory Control System read moreAbstract: Further developments of the inventory control strategy are studied in this brief. We use high gain (sliding mode) adaptive control to handle the system uncertainties caused by modeling errors and unmeasured disturbances. It is proven that this control law makes the uncertain system globally stable. The parameters of the resulting controller are easy to tune. The simulation example and experiment studies illustrate the application of the novel method. This article is not yet tagged | 2007 |
| | | Wang, J. | A Compact Slow-Wave Microstrip Branch-Line Coupler With High Performance read moreAbstract: One compact slow-wave microstrip branch-line coupler is presented. The new structure not only effectively reduces the occupied area to 28% of the conventional branch-line coupler at 2.0 GHz, but also has high second harmonic suppression performance. The measured results indicate a bandwidth of more than 200 MHz has been achieved while the phase difference between $S_{21}$ and $S_{31}$ is within 90$^{circ }, pm , {hbox{1}}^{circ}$ . Furthermore, the measured insertion loss is comparable to that of a conventional branch-line coupler. The new coupler can be easily implemented by using the standard printed-circuit-board etching processes and is very useful for wireless communication systems. This article is not yet tagged | 2007 |
2006
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| | | Chang, C. -. | Survey and comparative analysis of entropy and relative entropy thresholding techniques read moreAbstract: Entropy-based image thresholding has received considerable interest in recent years. Two types of entropy are generally used as thresholding criteria: Shannon's entropy and relative entropy, also known as Kullback-Leibler information distance, where the former measures uncertainty in an information source with an optimal threshold obtained by maximising Shannon's entropy, whereas the latter measures the information discrepancy between two different sources with an optimal threshold obtained by minimising relative entropy. Many thresholding methods have been developed for both criteria and reported in the literature. These two entropy-based thresholding criteria have been investigated and the relationship among entropy and relative entropy thresholding methods has been explored. In particular, a survey and comparative analysis is conducted among several widely used methods that include Pun and Kapur's maximum entropy, Kittler and Illingworth's minimum error thresholding, Pal and Pal's entropy thresholding and Chang et al.'s relative entropy thresholding methods. In order to objectively assess these methods, two measures, uniformity and shape, are used for performance evaluation This article is not yet tagged | 2006 |
2003
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| | | Wang, J. | 1.14-GHz self-aligned vibrating micromechanical disk resonator read moreAbstract: Sorry no abstract available for this article This article is not yet tagged | 2003 |
2002
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| | | Wang, J. | Enhancing the ENVISION interface for digital libraries read moreAbstract: visualization paper This article is not yet tagged | 2002 |
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