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AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference

作者： Haselbacher, A. Najjar, F.M. Massa, L. Moser, R.D. Center for Simulation of Advanced Rockets University of Illinois at Urbana-Champaign Urbana IL 61801 United States University of Texas at Austin Austin TX 78712 United States 2253 Digital Computer Laboratory MC-278 United States AIAA United States Mechanical Engineering Department United States

ISBN: (纸本)1563478188

Detailed first-principle computations of the flow in solid-propellant rocket motors (SRM) are challenging because of the wide range of length and time scales. In our computations, the time scale of primary interest is that of the evolution of turbulence. This time scale is much faster than the burn-out time scale, which makes the simulation of SRM burnout including turbulence very time-consuming. A detailed analysis of all the physical and numerical time scales suggests that an approach based on multi-scale asymptotics can be used to accelerate burn-out computations. Hence we have developed a new approach which allows acceleration of slow-time scales while leaving the evolution of fast time scales unchanged. Application of this approach to a simple SRM with center-perforated grain exhibits measured accelerations of up to a factor of 36. Our new approach is applicable not only to SRM computations, but to any physical system with widely separated time scales and for which the dynamics of the fast time scales are of primary interest. Copyright © 2006 by Center for Simulation of Advanced Rockets.

关键词： Rocket engines

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Number-of-band Selection for Acoustic Feedback Cancellation in Multi-band Compression Hearing Aids

Number-of-band Selection for Acoustic Feedback Cancellation ...

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IEEE Region 10 International Conference TENCON

作者： P. Chaisakul N. Tangsangiumvisai P. Luangpitakchumpon Digital Signal Processing Research Laboratory Department of Electrical Engineering Chulalongkom University Bangkok Thailand Department of Otolaryngology Faculty of Medicine Chulalongkom University Bangkok Thailand

In this paper, the effect of numbers of bands for acoustic feedback cancellation (AFC) in multi-band compression hearing aids is investigated. Significant improvement in the performance of the AFC system is demonstrated via computer simulations based on different hearing loss characteristics. Moreover, the increment of the dynamic range of hearing when employing multi-band compression hearing aids is shown, as compared to that of conventional hearing aids

关键词： Feedback Hearing aids Automatic frequency control Deafness Acoustic devices Auditory system Dynamic range Speech Filter bank Microphones

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An memory-efficient variable length decoding scheme for embedded MPEG-4 video decoders

An memory-efficient variable length decoding scheme for embe...

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International Conference on Signal Processing Proceedings (ICSP)

作者： Hongxing Guo Xiaojian Xia Weiping Sun Jingli Zhou Shengsheng Yu Department of Computer Science and Engineering Division of Data Storage System of Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan China

Variable length decoding (VLD) is inherent bit-serial operation and is the first stage of the whole video decoding task, the overall decoding system performance is determined by its throughput and efficiency. In this paper, a scheme for decoding of discrete cosine transform (DCT) coefficients is presented The DCT VLD tables are split into two different tables: the one with 0-3 leading zeros and the other with 4 or more leading zeros. The proposed VLD tables need less than 6K bytes memory space, and the decoding procedures are completed by applying numerical properties to codewords identification and symbol indexing. Compared with the direct indexing method, not only the memory space is reduced for symbol information, but also the code efficiency is improved by enabling compiling code with near mode. Experimental results show that the proposed solution can improve the VLD speed by 17-43%. This VLD method has been integrated into the developed embedded MPEG-4 video decoder successfully

关键词： Decoding MPEG 4 Standard Discrete cosine transforms Table lookup digital signal processing system performance Throughput Indexing Sun computer science

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New load models for fast transient stability calculations

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International Journal of Power and Energy systems 2006年第1期26卷 49-57页

作者： Ai, Q. Domijan Jr., A. Department of Electrical Engineering Shanghai Jiao Tong University Shanghai 200030 China Florida Power Affiliates Department of Electrical and Computer Engineering University of Florida Gainesville FL 32611 United States Shanghai Jiao Tong University Electrical Engineering Faculty University of Florida Florida Power Affiliates Power Quality Laboratory

Load models play an important role in the simulation and evaluation of power system performance. This article proposes a new load model, which is based on a particular form of artificial neural networks we denote as adaptive back-propagation (ABP) network. ABP can overcome some of shortcomings of common back-propagation (BP), and the ABP load models offer several advantages over traditional load models, as they are nonstructural and can be derived quickly. The application of the method is illustrated using actual field test data. The load models so obtained are shown to replicate the test measurements more closely than those based on traditional load models. Extension of the method to identification of the parameters of the traditional load models is also proposed. It is based on linear back-propagation (LBP) network. The proposed LBP load model is incorporated in a transient stability program to show that the computational time is significantly reduced.

关键词： Transients

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Multimodal priority verification of face and speech using momentum back-propagation neural network

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3rd International Symposium on Neural Networks, ISNN 2006 - Advances in Neural Networks

作者： Park, Changhan Ki, Myungseok Namkung, Jaechan Paik, Joonki Department of Image Engineering Graduate School of Advanced Imaging Science Multimedia and Film Chung-Ang University 221 Huksuk-dong Tongjak-Ku Seoul 156-756 Korea Republic of Broadcasting Media Research Group Digital Broadcasting Research Division ETRI 161 Gajeong-dong Yuseong-Gu Daejeon 305-700 Korea Republic of Intelligent Image Communication Laboratory Department of Computer Engineering Kwangwoon University 447-1 Wolge-dong Nowon-Gu Seoul 139-701 Korea Republic of

ISBN: (纸本)3540344373

In this paper, we propose a priority verification method for multimodal biometric features by using a momentum back-propagation artificial neural network (MBP-ANN). We also propose a personal verification method using both face and speech to improve the rate of single biometric verification. False acceptance rate (FAR) and false rejection rate (FRR) have been a fundamental bottleneck of real-time personal verification. The proposed multimodal biometric method is to improve both verification rate and reliability in real-time by overcoming technical limitations of single biometric verification methods. The proposed method uses principal component analysis (PCA) for face recognition and hidden markov model (HMM) for speech recognition. It also uses MBPANN for the final decision of personal verification. Based on experimental results, the proposed system can reduce FAR down to 0.0001%, which proves that the proposed method overcomes the limitation of single biometric system and proves stable personal verification in real-time. © Springer-Verlag Berlin Heidelberg 2006.

关键词： Neural networks

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Effects of digital filtering technique in reducing the effects of clipping of an enhanced orthogonal frequency division multiplexing system

Effects of digital filtering technique in reducing the effec...

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International Symposium on Wireless Pervasive Computing (ISWPC)

作者： W.H. Wan Hassan S. Khatun Center for Foundation Education and Extension Education Multimedia University Malacca Malaysia Department of Computer and Communication System Faculty of Engineering Universiti Putra Malaysia Selangor Darul Ehsan Malaysia

Despite of the many advantages of OFDM, it has two main drawbacks which are high peak to average power ratio (PAPR) and synchronization problem. High PAPR causes saturation in power amplifiers, leading to intermodulation products among the sub carriers and disturbing out of band energy. Therefore, it is desirable to reduce the PAPR by means of PAPR reduction schemes. However, it caused the degradation of BER and enhanced the growth of out of band radiation which has led to the degradation of OFDM overall performance. In this paper, OFDM system with an enhanced clipping technique has been proposed, the effects of clipping have been analyzed and the system is evaluated by integrating with its significant features including convolutional forward error control coding, oversampled inverse fast Fourier transform (IFFT) and digital filtering technique in order to minimize the effects of clipping. It is shown that the bit error rate (BER) of the clipped OFDM signal is improved, the PAPR is further reduced and the effect of out of band radiation is minimized. Besides, other effects of the filtering technique are also analyzed in order to optimize the overall performance of our proposed system.

关键词： digital filters Filtering OFDM Peak to average power ratio Bit error rate Degradation Frequency synchronization High power amplifiers Convolutional codes Convolution

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Robust Adaptive Control for Complex systems Employing ANN Emulation of Nonlinear Functions

Robust Adaptive Control for Complex Systems Employing ANN Em...

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Seminar on Neural Network Applications in Electrical engineering

作者： Georgi M. Dimirovski Yuanwei Jing Yanxin Zhang Miomir K. Vukobratovic Faculty of Electrical Engineering SS Cyril and Methodius University Skopje Macedonia Department of Computer Engineering Dogus University Kadikoy Istanbul Turkey School of Information Science and Engineering Northeastern University Shenyang China Laboratory of Robotics & Flexible Automation Mihajlo Pupin Institute Belgrade Serbia

A new robust adaptive control design synthesis, which employs both high-order neural networks and math-analytical results, for a class of complex nonlinear mechatronic systems possessing similarity property has been derived. This approach makes an adequate use of the structural feature of composite similarity systems and neural networks to resolve the representation issue of uncertainty interconnections and subsystem gains by on-line updating the weights. This synthesis does guarantee the real stability in closed-loop but requires skills to obtain larger attraction domains. Mechatronic example of an axis-tray drive system, possessing uncertainties, is used to illustrate the proposed technique

关键词： Robust control Adaptive control Emulation Network synthesis Neural networks Mechatronics Uncertainty Artificial neural networks Control system synthesis Stability

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Research on a Throwing Multidimensional Force Sensing system for Advanced Training of Shot-Put Athletes

Research on a Throwing Multidimensional Force Sensing System...

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International Conference on Information and Automation (ICIA)

作者： Zhen Gao Quanjun Song Ming Liu Jianhe Lei Yong Yu Yunjian Ge State Key laboratory of Robot Sensing System Institute of Intelligent Machines Chinese Academy and Sciences Hefei Anhui China Department of Electrical and Computer Systems Engineering Monash University Melbourne VIC Australia

In this paper, we develop a novel digital-shot system for sensing the throwing force information of shot-put athletes in real time. The digital-shot has been designed and manufactured with the same external dimensions and weight as the normal shot for open females. The three axes integrated accelerometer, as a crucial device in the force sensing system, can acquire the kinetics data along three orthogonal directions with reasonably high accuracy. By using the method of wavelet transformation, the characteristics of acceleration signals during the shot-put period can be extracted. Artificial neural network is adopted to recognise the movement pattern in different phases of shot throwing. For supplying more effective training instruction, with the help of six axes ground reaction force measuring apparatus, high-speed photography and surface electromyographic signal remote measuring device etc, an integrated platform of shot-put athlete biomechanical information acquisition is constructed. Based on the fusion of multi-targets and multi-parameters information, the shot-put athletes coaching system is proposed, which not only can supply constructive guidance for athletes to improve their skills, but also provide a new research platform of motion human modeling.

关键词： Multidimensional systems Force measurement Real time systems Manufacturing Accelerometers Kinetic theory Acceleration Data mining Artificial neural networks Pattern recognition

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Italian-Croatian Remote laboratory Distributed on Geographical Network

Italian-Croatian Remote Laboratory Distributed on Geographic...

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International Conference on Software, Telecommunications and computer Networks (SoftCOM)

作者： Mladen Borsic Drago Cmuk Pasquale Daponte Claudio De Capua Domenico Grimaldi Tomislav Kilic Tarik Mutapcic Maria Riccio Faculty of Electrical Engineering and Computing Zagreb Croatia Department of Engineering University of Sannio Benevento Italy Dipartimento Informatica Matematica Elettronica e Trasporti University E2809CMediterraneaE2809D Reggio Calabria Italy Department of Electronics Computer and System Science University of Calabria Rende Cosenza Italy Faculty of Electrical Engineering Mechanical Engineering and Naval Architecture University of Split FESB Split Croatia Tarmel d. o. o Zagreb Croatia Didagroup S.p.A. San Giorgio del Sannio Italy

The paper presents the e-learning project and the work until now developed for extending the features of the Italian remote laboratory "G. Savastano" to the academic circles of East Europe, Western Balkan and Mediterranean area. In particular, in the framework of the project "Italian-Croatian remote laboratory distributed on geographic network", the Italian-Croatian collaboration is highlighted. The proposed approach follows EU efforts to implement internal lifelong learning program and influence educational systems of EU partners and neighbor Countries while helping them to overcome problems with their own educational systems and lack of resources. Developed experiments, included in the remote laboratory, give the possibility of achieving practical experience on several fields, while multilingual approach gives the access to such facility to the students coming from different countries. Moreover, the idea of interactively controlled transfer of knowledge and experience offers new opportunities to the remote experiments enabling them to be executed without supervising necessity

关键词： Remote laboratories Educational programs Education Europe Internet Electronic learning Vocational training Instruments Collaborative software computer networks

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Tailor-made tricalcium phosphate bone implant directly fabricated by a three-dimensional ink-jet printer

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Journal of Artificial Organs 2006年第4期9卷 234-240页

作者： Igawa, Kazuyo Mochizuki, Manabu Sugimori, Osamu Shimizu, Koutaro Yamazawa, Kenji Kawaguchi, Hiroshi Nakamura, Kozo Takato, Tsuyoshi Nishimura, Ryouhei Suzuki, Shigeki Anzai, Masahiro Chung, Ung-Il Sasaki, Nobuo Division of Tissue Engineering University of Tokyo Hospital Bunkyo-ku Tokyo 113-8655 7-3-1 Hongo Japan Laboratory of Veterinary Diagnostic Imaging Department of Veterinary Medicine Tokyo University of Agriculture and Technology Tokyo Japan Laboratory of Veterinary Surgery Graduate School of Agricultural and Life Sciences University of Tokyo Tokyo Japan New X-national Technology K.K. Tokyo Japan Advanced Development and Supporting Center RIKEN Wako Japan Division of Sensory and Motor System Medicine Faculty of Medicine University of Tokyo Tokyo Japan

Rapid prototyping (RP) is a molding technique that builds a three-dimensional (3D) model from computer-aided design (CAD) data. We fabricated new tailor-made bone implants (TIs) from α-tricalcium phosphate powder using an RP ink-jet printer based on computed tomography (CT) data, and evaluated their safety and efficacy. CT data of the skulls of seven beagle dogs were obtained and converted to CAD data, and bone defects were virtually made in the skull bilaterally. TIs were designed to fit the defects and were fabricated using the 3D ink-jet printer with six horizontal cylindrical holes running through the implants, designed for possible facilitation of vascular invasion and bone regeneration. As a control, hydroxyapatite implants (HIs) were cut manually from porous hydroxyapatite blocks. Then, craniectomy was performed to create real skull defects, and TIs and HIs were implanted. After implantation, CT was performed regularly, and the animals were euthanized at 24 weeks. No major side effects were observed. CT analysis showed narrowing of the cylindrical holes;bony bridging between the implants and the temporal bone was observed only for TIs. Histological analysis revealed substantial new bone formation inside the cylindrical holes in the TIs, while mainly connective tissues invaded the porous structures in HIs. Bone marrow was observed only in TIs. Osteoclasts were seen to resorb regenerated bone from inside the cylindrical holes and to invade and probably resorb the TIs. These data suggest that TIs are a safe and effective bone substitute, possessing osteoconductivity comparable with that of HIs. © 2006 The Japanese Society for Artificial Organs.

关键词： Biodegradability Bone substitute Tailor-made implant Three-dimensional ink-jet printer Tricalcium phosphate

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