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PLC在变频闭环调速系统中的应用 被引量:6
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作者 李宁 《价值工程》 2011年第7期151-153,共3页
本文以西门子s7-200PLC、变频器和旋转编码器组成的交流变频闭环调速系统为例,介绍了基于PLC的变频闭环调速系统的工作原理、设计与实施方法,阐述了PLC在变频闭环调速控制系统中应用和实施过程的关键技术,并指出了系统在设计与实施过程... 本文以西门子s7-200PLC、变频器和旋转编码器组成的交流变频闭环调速系统为例,介绍了基于PLC的变频闭环调速系统的工作原理、设计与实施方法,阐述了PLC在变频闭环调速控制系统中应用和实施过程的关键技术,并指出了系统在设计与实施过程中中应注意的问题。 展开更多
关键词 PLC 变频器:旋转编码 交流闭环调速
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基于PLC为核心的多重反馈教学系统设计
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作者 林祥勇 王秋霞 《机械与电子》 2017年第1期46-48,共3页
针对机电、电气专业学生目前开设的电气控制类课程现状,设计一款以提高高职学生技能训练水平为目的的多重反馈教学系统。该系统以PLC开关量控制为核心,融合了AD、DA、变频编码和伺服控制等专业综合技术,可根据实验需要自主构建开环、半... 针对机电、电气专业学生目前开设的电气控制类课程现状,设计一款以提高高职学生技能训练水平为目的的多重反馈教学系统。该系统以PLC开关量控制为核心,融合了AD、DA、变频编码和伺服控制等专业综合技术,可根据实验需要自主构建开环、半闭环、闭环反馈,并进行了典型闭环系统设计。 展开更多
关键词 教学系统 PLC 变频编码 伺服控制 多重反馈
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A VIDEO SPECTRUM SPLITTING ENCODING SCHEME BASED ON HUMAN VISION AND ITS COMPUTER SIMULATION
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作者 赵宇 李华 +1 位作者 俞斯乐 滕建辅 《Transactions of Tianjin University》 EI CAS 1995年第1期79+76-79,共5页
In this paper, a 3-D video encoding scheme suitable for digital TV/HDTV (high definition television) is studied through computer simulation. The encoding scheme is designed to provide a good match to human vision. Bas... In this paper, a 3-D video encoding scheme suitable for digital TV/HDTV (high definition television) is studied through computer simulation. The encoding scheme is designed to provide a good match to human vision. Basically, this involves transmission of low frequency luminance information at full frame rate for good motion rendition and transmission of high frequency luminance signal at reduced frame rate for good detail in static images. 展开更多
关键词 D video encoding discrete wavelet transform human vision computer simulation
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Source extension based on ε-entropy 被引量:3
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作者 张剑 《Journal of Chongqing University》 CAS 2005年第2期102-106,共5页
It is known by entropy theory that image is a source correlated with a certain characteristic of probability. The entropy rate of the source and ε- entropy (rate-distortion function theory) are the information conten... It is known by entropy theory that image is a source correlated with a certain characteristic of probability. The entropy rate of the source and ε- entropy (rate-distortion function theory) are the information content to identify the characteristics of video images, and hence are essentially related with video image compression. They are fundamental theories of great significance to image compression, though impossible to be directly turned into a compression method. Based on the entropy theory and the image compression theory, by the application of the rate-distortion feature mathematical model and Lagrange multipliers to some theoretical problems in the H.264 standard, this paper presents a new the algorithm model of coding rate-distortion. This model is introduced into complete test on the capability of the test model of JM61e (JUT Test Model). The result shows that the speed of coding increases without significant reduction of the rate-distortion performance of the coder. 展开更多
关键词 Rate-Distortion function LAGRANGIAN source extension Theory of information video coding image compression
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Turbo-Coded Modulation of EVRC Speech Encoder with Unequal Error Protection for Fading Channels
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作者 阿哈麦德 潘志文 +1 位作者 高西奇 尤肖虎 《Journal of Shanghai Jiaotong university(Science)》 EI 2003年第2期150-156,共7页
The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Persona... The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45 dB at BER of 10 -5. 展开更多
关键词 enhanced variable rate codec (EVRC) turbo codes unequal error protection (UEP) quadrature amplitude modulation (QAM)
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ALL ZERO MACROBLOCK DECISION METHOD FOR H.26L 被引量:1
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作者 OuJianping 《Journal of Electronics(China)》 2004年第3期222-228,共7页
In order to reduce the computation in the part of motion search and transform in H.26L encoder, an all-zero macroblock decision method based on integer transform and motion search is proposed in this paper. According ... In order to reduce the computation in the part of motion search and transform in H.26L encoder, an all-zero macroblock decision method based on integer transform and motion search is proposed in this paper. According to the characteristics of integer transform and motion search in H.26L, all-zero macroblock decision is made in inter frame coding by comparing Sum of the Absolute Differences(SAD) with a value related with Quantization Parameter(QP)before integer transform. It avoids a large amount of computation in motion search, transform and quantization. This technology highly improves the efficiency of real time H.26L encoder by skipping all-zero macroblock before integer transform and shortening the code stream at the same time. 展开更多
关键词 H.26L All-zero macroblock decision Integer transform Sum of the Absolute Differences(SAD)
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广义条纹图序列编码的相位重建 被引量:6
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作者 彭翔 韦林彬 +1 位作者 邱文杰 田劲东 《光学学报》 EI CAS CSCD 北大核心 2006年第8期1156-1161,共6页
为解决拓扑复杂物体三维数字化过程中的绝对相位测量及相位重建问题,提出了一种广义变频条纹图序列的相位展开算法。简要综述了现有的各种时间维相位展开算法并指出这些算法存在的问题,在此基础上,详细分析比较提出方法与正指数条纹序... 为解决拓扑复杂物体三维数字化过程中的绝对相位测量及相位重建问题,提出了一种广义变频条纹图序列的相位展开算法。简要综述了现有的各种时间维相位展开算法并指出这些算法存在的问题,在此基础上,详细分析比较提出方法与正指数条纹序列算法的噪声免疫力和时间复杂度,证明该方法有更高的噪声免疫力和更低的时间复杂度。特别是,当相邻编码条纹图的条纹数之比不等于2时,正指数条纹序列算法出现严重噪声,而提出的方法依然能够正常工作。此外,该算法还能够根据实际情况决定需要投影的条纹频率,从而能够使用相对较少的条纹编码图像进行有效的相位展开,进而提高系统的实时性。理论分析和实验结果都证明了提出算法的有效性。 展开更多
关键词 信息光学 三维形貌测量 条纹自动分析 相位重建 变频编码
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AN IMPROVED ALL ZERO BLOCK FINDING METHOD BASED ON THE STATISTIC CHARACTERISTICS OF DCT TRANSFORM COEFFICIENTS
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作者 Xi Yinglai Hao Chongyang 《Journal of Electronics(China)》 2006年第1期99-102,共4页
In the H.263 video codec related systems, motion estimation and Discrete Cosine Transform (DCT) have the most computational requirements. In order to reduce complexity of the encoder to dedicate more resources to othe... In the H.263 video codec related systems, motion estimation and Discrete Cosine Transform (DCT) have the most computational requirements. In order to reduce complexity of the encoder to dedicate more resources to other functions, according to the study of existing methods, an Improved All Zero Block Finding (IAZBF) method based on the statistic characteristics of DCT coefficients is proposed. Compared with existing methods, IAZBF improves the detecting efficiency by about 50% without importing too much extra computation requirement. Being computed with additions and shifts instead of complicated multiplications, IAZBF is of low computation complexity, especially for low-end processors. In addition, IAZBF upholds picture fidelity and remains compatible with the H.263 bitstream standard. 展开更多
关键词 Discrete Cosine Transform (DCT) All-zero blocks Computation reduction
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STUDY ON FREQUENCY CODING ANTI-INTERFERENCE SYSTEM FOR DATA TRANSMISSION IN SHALLOW WATER ACOUSTIC CHANNELS
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作者 许肖梅 粘宝卿 +2 位作者 刘志鑫 许鹭芬 黄衍镇 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2002年第4期309-315,共7页
Achieving reliable underwater communication in shallow water acoustic channels is a difficult task because of the random time varying nature of multipath propagation, severe amplitude fluctuation, and spatial variabil... Achieving reliable underwater communication in shallow water acoustic channels is a difficult task because of the random time varying nature of multipath propagation, severe amplitude fluctuation, and spatial variability of the channel conditions. This paper describes a new signal processing technique frequency coding and decoding by means of real time measurement of signal width, jamming and suppressing multipath interference and using redundant coder. The application of the technique to the model ZTY 1 status monitor for underwater system of seabed is introduced in this paper. The main principle, the technique specifications and the key techniques of the system are discussed here. Theoretical estimations and experimental results proved that the performance of the system is excellent. The method can be used for some other related low data rate data transmission detecting in shallow water acoustic channel. 展开更多
关键词 acoustic channels frequency coding anti interference
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微小半径圆弧轨道双向门机大车行走机构研制 被引量:1
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作者 黄文峰 《水电站机电技术》 2020年第3期57-58,共2页
针对微小半径门机能平稳运行采取的新型回转支撑结构型式、采用大小车轮确保内外弧车轮同步性、增加水平轮和车轮踏面的宽度防止车轮出现啃轨和卡轨现象、采用变频电机和编码器确保车轮转速的一致性等措施,进行了研究分析。
关键词 赞比亚下凯富峡水电站 微小半径圆弧轨道 大车行走机构 回转支承 大小车轮 水平轮 变频调速和绝对值编码
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A reversibility-gain model for integer Karhunen-Loève transform design in video coding
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作者 Xing-guo ZHU Lu YU 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2015年第10期883-891,共9页
Karhunen-Loeve transform (KLT) is the optimal transform that minimizes distortion at a given bit allocation for Gaussian source. As a KLT matrix usually contains non-integers, integer-KLT design is a classical probl... Karhunen-Loeve transform (KLT) is the optimal transform that minimizes distortion at a given bit allocation for Gaussian source. As a KLT matrix usually contains non-integers, integer-KLT design is a classical problem. In this paper, a joint reversibility-gain (R-G) model is proposed for integer-KLT design in video coding. Specifically, the 'reversibility' is modeled according to distortion analysis in using forward and inverse integer transform without quantization. It not only measures how invcrtible a transform is, but also bounds the distortion introduced by the non-orthonormal integer transform process. The 'gain' means transform coding gain (TCG), which is a widely used criterion for transform design in video coding. Since KLT maximizes the TCG under some assumptions, here we define the TCG loss ratio (LR) to measure how much coding gain an integer-KLT loses when compared with the original KLT. Thus, the R-G model can be explained as follows: subject to a certain TCG LR, an integer- KLT with the best reversibility is the optimal integer transform for a given non-integer-KLT. Experimental results show that the R-G model can guide the design of integer-KLTs with good performance. 展开更多
关键词 Integer transform Karhunen-Loeve transform (KLT) Integer-KLT Transform coding Video coding
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Analysis of hypermutation of the 5' noncoding region in the BCL-6 gene
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作者 王林 刘建湘 +9 位作者 黄薇 王辉东 王建民 顾柏炜 陈竺 陈赛娟 许良中 杨文涛 金晓龙 柳红 《Chinese Medical Journal》 SCIE CAS CSCD 2001年第3期62-66,107,共6页
ObjectiveTo investigate BCL 6 gene mutations in Chinese populations with B cell non Hodgkin's lymphoma Methods Polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and direct D... ObjectiveTo investigate BCL 6 gene mutations in Chinese populations with B cell non Hodgkin's lymphoma Methods Polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and direct DNA sequencing were used to identify mutations in the 5' noncoding region of the BCL 6 gene in a total of 40 cases of diffuse large cell lymphoma (DLCL) and follicular lymphoma (FL) Results Nine cases were found to have base substitutions The incidence of BCL 6 gene mutation and the frequency of single base changes were approximately 25 7% and (0 56-1 10)×10 2 /bp, respectively Conclusions The 5' regulatory region of the BCL 6 gene undergoes frequent somatic hypermutation during lymphomagenesis and the identification of BCL 6 gene hypermutations provides a molecular marker for confirmatory diagnosis of B NHL 展开更多
关键词 BCL 6 gene · 5' noncoding region · hypermutation · diffuse large cell lymphoma · follicular lymphoma
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