三相PWM逆变器软开关动作时序分析

通过对软开关三相PWM逆变器的研究和实验，针对在实验中出现谐振槽不正常的现象，分析了本软开关电路拓扑下实现软开关动作的工作原理及谐振动作时序，阐述了PWM驱动信号与谐振电路的动作时序间的关系，指出要使谐振能正常进行，必须要使PWM驱动信号的开通动作控制在谐振电感的电流iLr变为负之前，这样才能在直流母线电压上出现一个完整的谐振槽，保证逆变器主电路开关管实现软开关动作。     

管理信息系统中流水号生成方法与实现

在管理信息系统中，生成、控制和管理流水号十分重要。基于Oracle数据库系统，讨论了序号生成器sequence的基本用法，描述了一种产生连续或非连续流水号的优化方法及实现步骤，同时扩展了序号生成器的用法。结合具体流水号数据的特点和存放格式，给出了PowerBuilder的生成序列号函数实例、主要程序代码以及调用方法。在实际应用中，某大型管理信息系统采用了这种设计方法，取得了较好的效果。     

Practical crack control during the construction of precast segmental box girder bridges

Cracks that occurred in the bottom slab of a precast segmental bridge were investigated through a construction sequence analysis, which revealed that the cracks were caused by excessive deformation during temporary post-tensioning while joining the segments. In addition, a parametric study was performed to evaluate the effects of the prestressing sequence, bottom slab thickness, and position of the prestressing anchors. The structural behavior of the girder sections was greatly affected by the thickness of the bottom slab and the position of prestressing anchors, but not by the prestressing sequence. Based on the results, a construction method that prevents the cracks is proposed.     

An algorithm for similar utterance section extraction for managing spoken documents

This paper proposes a new, efficient algorithm for extracting similar sections between two time sequence data sets. The algorithm, called Relay Continuous Dynamic Programming (Relay CDP), realizes fast matching between arbitrary sections in the reference pattern and the input pattern and enables the extraction of similar sections in a frame synchronous manner. In addition, Relay CDP is extended to two types of applications that handle spoken documents. The first application is the extraction of repeated utterances in a presentation or a news speech because repeated utterances are assumed to be important parts of the speech. These repeated utterances can be regarded as labels for information retrieval. The second application is flexible spoken document retrieval. A phonetic model is introduced to cope with the speech of different speakers. The new algorithm allows a user to query by natural utterance and searches spoken documents for any partial matches to the query utterance. We present herein a detailed explanation of Relay CDP and the experimental results for the extraction of similar sections and report results for two applications using Relay CDP. Yoshiaki Itoh has been an associate professor in the Faculty of Software and Information Science at Iwate Prefectural University, Iwate, Japan, since 2001. He received the B.E. degree, M.E. degree, and Dr. Eng. from Tokyo University, Tokyo, in 1987, 1989, and 1999, respectively. From 1989 to 2001 he was a researcher and a staff member of Kawasaki Steel Corporation, Tokyo and Okayama. From 1992 to 1994 he transferred as a researcher to Real World Computing Partnership, Tsukuba, Japan. Dr. Itoh's research interests include spoken document processing without recognition, audio and video retrieval, and real-time human communication systems. He is a member of ISCA, Acoustical Society of Japan, Institute of Electronics, Information and Communication Engineers, Information Processing Society of Japan, and Japan Society of Artificial Intelligence. Kazuyo Tanaka has been a professor at the University of Tsukuba, Tsukuba, Japan, since 2002. He received the B.E. degree from Yokohama National University, Yokohama, Japan, in 1970, and the Dr. Eng. degree from Tohoku University, Sendai, Japan, in 1984. From 1971 to 2002 he was research officer of Electrotechnical Laboratory (ETL), Tsukuba, Japan, and the National Institute of Advanced Science and Technology (AIST), Tsukuba, Japan, where he was working on speech analysis, synthesis, recognition, and understanding, and also served as chief of the speech processing section. His current interests include digital signal processing, spoken document processing, and human information processing. He is a member of IEEE, ISCA, Acoustical Society of Japan, Institute of Electronics, Information and Communication Engineers, and Japan Society of Artificial Intelligence. Shi-Wook Lee received the B.E. degree and M.E. degree from Yeungnam University, Korea and Ph.D. degree from the University of Tokyo in 1995, 1997, and 2001, respectively. Since 2001 he has been working in the Research Group of Speech and Auditory Signal Processing, the National Institute of Advanced Science and Technology (AIST), Tsukuba, Japan, as a postdoctoral fellow. His research interests include spoken document processing, speech recognition, and understanding.     

Robust multi bit and high quality audio watermarking using pseudo-random sequences

A robust multi bit and high quality audio watermarking technique in time domain is proposed in this paper. Watermarking is a technique used to label digital media by hiding copyright or other information into the underlying data. The watermark must be imperceptible and undetectable by the user and should be robust to various types of distortion. To enhance the robustness and taper-resistance of the embedded watermark, in this paper a multi bit technique is employed. Instead of embedding one bit into an audio frame, multiple bits can be embedded into each audio sub-frame. For attackers, since they do not know the parameters, this significantly reduces the possibility of unauthorized bit detection and removal of watermark. In real-time watermarking applications, robustness is not the only factor that plays an important role. The other factor that plays a very an important role is computational complexity. In general, audio file is transmitted in compressed form. Real-time watermark embedding must take into account this compressed form, because first decompressing the data, adding a watermark and then recompressing the data is computationally too demanding. In this paper, we propose robust and low complexity audio watermarking algorithm. To evaluate the performance of the proposed audio watermarking algorithm, subjective and objective quality tests including bit error rate (BER) and signal-to-noise ratio (SNR) were conducted. Compared to traditional one bit embedding algorithm, the proposed algorithm gives highly recovery rate after attack by commonly used audio data manipulations, such as low pass filtering, requantization, resampling, and MP3 compression.     

Practical methods for constructing suffix trees

Sequence datasets are ubiquitous in modern life-science applications, and querying sequences is a common and critical operation in many of these applications. The suffix tree is a versatile data structure that can be used to evaluate a wide variety of queries on sequence datasets, including evaluating exact and approximate string matches, and finding repeat patterns. However, methods for constructing suffix trees are often very time-consuming, especially for suffix trees that are large and do not fit in the available main memory. Even when the suffix tree fits in memory, it turns out that the processor cache behavior of theoretically optimal suffix tree construction methods is poor, resulting in poor performance. Currently, there are a large number of algorithms for constructing suffix trees, but the practical tradeoffs in using these algorithms for different scenarios are not well characterized. In this paper, we explore suffix tree construction algorithms over a wide spectrum of data sources and sizes. First, we show that on modern processors, a cache-efficient algorithm with O(n²) worst-case complexity outperforms popular linear time algorithms like Ukkonen and McCreight, even for in-memory construction. For larger datasets, the disk I/O requirement quickly becomes the bottleneck in each algorithm's performance. To address this problem, we describe two approaches. First, we present a buffer management strategy for the O(n²) algorithm. The resulting new algorithm, which we call “Top Down Disk-based” (TDD), scales to sizes much larger than have been previously described in literature. This approach far outperforms the best known disk-based construction methods. Second, we present a new disk-based suffix tree construction algorithm that is based on a sort-merge paradigm, and show that for constructing very large suffix trees with very little resources, this algorithm is more efficient than TDD.     

Terminating Renewal Processes: Analytical-Statistical Estimates and Their Efficiency

An approach is proposed to the construction of different unbiased analytical-statistical estimates for calculation of the termination time of different renewal processes by the Monte Carlo method. The processes are typical of queuing systems, reliability theory, and risk analysis of renewal processes and to the analysis of their efficiency using the algorithmic language Maple V.The results were obtained during two scientific visits to the STORM Research Center of the University of North London in 1998–1999 with a sponsor support from the Royal Society in Great Britain and within the framework of the project UKR-01-008.__________Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 138–155, January–February 2005.     

On the Expressiveness of Higher Dimensional Automata: (Extended Abstract)

In this paper I compare the expressive power of several models of concurrency based on their ability to represent causal dependence. To this end, I translate these models, in behaviour preserving ways, into the model of higher dimensional automata, which is the most expressive model under investigation. In particular, I propose four different translations of Petri nets, corresponding to the four different computational interpretations of nets found in the literature.I also extend various equivalence relations for concurrent systems to higher dimensional automata. These include the history preserving bisimulation, which is the coarsest equivalence that fully respects branching time, causality and their interplay, as well as the ST-bisimulation, a branching time respecting equivalence that takes causality into account to the extent that it is expressible by actions overlapping in time. Through their embeddings in higher dimensional automata, it is now well-defined whether members of different models of concurrency are equivalent.     

A 12-b, 150 MHz Sample/s CMOS Current Steering D/A Converter with Gradient Error Compensation

This paper discusses a circuit of 12-b, 150 MHz Sample/s current steering DAC with hierarchical symmetrical switching sequences which will compensate gradient error. The circuit of 12-b DAC employs segmented architecture, the least significant bits (LSB's) steer a binary weighted array, while the most significant bits (MSB's) are thermometer decoded and steer a unary array. The measured differential nonlinearity and integral nonlinearity are ± 0.6 least significant bit (LSB) and ±0.9 LSB, respectively. The output spectrum of the DAC is −63 dB with an input frequency of 30 MHz at 150 MHz conversion rate. The circuit is fabricated in 0.5 μ μm, two-poly two-metal, 5.0 V, mixed-signal CMOS process and occupies 1.27 × 0.96 mm, when operating at 150 MHz Sample/s, it dissipates 91.6 mW from 5.0 V power supply which is much lower than those of [1]. Jinguang Jiang received the M.Sc. degree from Hunan University, Hunan, China, in 1998 and the PhD degree from Hunan University, Hunan, China, in 2003, all in Electrical Engineering. He is currently a Postdoctoral fellow of Control Science and Engineering in the Faculty of Electrical and Information Engineering at the University of Hunan. His interests are mode distinguish and intelligent system, intelligent signal process, low-power and low-voltage analog integrated circuits design. Bo Wang received the M.Sc. degree from Southeast University, China, in 1998. He is currently as a senior analog design engineer working at Caretta Integrated Circuits, Shanghai, China. His interests are high-speed analog IC design and analog system modeling and analysis. Yaonan Wang received the M.Sc. degree from Hunan University, Hunan, China, in 1991 and the Ph.D. degree from Hunan University, Hunan, China, in 1994, all in Control Theory and Control Engineering. He is currently a Professor and dean of school of Electrical and Information Engineering at the University of Hunan. He is engaged in research of intelligent control, intelligent signal process, image distinguish and its application.