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Journal of Zhejiang University. Science最新文献

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Mathematical modeling of salt-gradient ion-exchange simulated moving bed chromatography for protein separations. 盐梯度离子交换的数学模型模拟了蛋白质分离的移动床色谱。
Journal of Zhejiang University. Science Pub Date : 2004-12-01 DOI: 10.1631/jzus.2004.1613
Jian-Gang Lu
{"title":"Mathematical modeling of salt-gradient ion-exchange simulated moving bed chromatography for protein separations.","authors":"Jian-Gang Lu","doi":"10.1631/jzus.2004.1613","DOIUrl":"https://doi.org/10.1631/jzus.2004.1613","url":null,"abstract":"<p><p>The salt-gradient operation mode used in ion-exchange simulated moving bed chromatography (SMBC) can improve the efficiency of protein separations. A detailed model that takes into account any kind of adsorption/ion-exchange equilibrium, salt gradient, size exclusion, mass transfer resistance, and port periodic switching mechanism, was developed to simulate the complex dynamics. The model predictions were verified by the experimental data on upward and downward gradients for protein separations reported in the literature. All design and operating parameters (number, configuration, length and diameter of columns, particle size, switching period, flow rates of feed, raffinate, desorbent and extract, protein concentrations in feed, different salt concentrations in desorbent and feed) can be chosen correctly by numerical simulation. This model can facilitate the design, operation, optimization, control and scale-up of salt-gradient ion-exchange SMBC for protein separations.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 12","pages":"1613-20"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1613","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24816007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
An adaptive mechanism to guarantee the bandwidth fairness of TCP flows. 保证TCP流带宽公平性的自适应机制。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1361
Shun-liang Zhang, Cheng-qing Ye
{"title":"An adaptive mechanism to guarantee the bandwidth fairness of TCP flows.","authors":"Shun-liang Zhang,&nbsp;Cheng-qing Ye","doi":"10.1631/jzus.2004.1361","DOIUrl":"https://doi.org/10.1631/jzus.2004.1361","url":null,"abstract":"<p><p>End-to-end TCP (transmission control protocol) congestion control can cause unfairness among multiple TCP connections with different RTT (Round Trip Time). The throughput of TCP connection is inversely proportional to its RTT. To resolve this problem, researchers have proposed many methods. The existing proposals for RTT-aware conditioner work well when congestion level is low. However, they over-protect long RTT flows and starve short RTT flows when congestion level is high. Due to this reason, an improved method based on adaptive thought is proposed. According to the congestion level of networks, the mechanism can adaptively adjust the degree of the protection to long RTT flows. Extensive simulation experiments showed that the proposed mechanism can guarantee the bandwidth fairness of TCP flows effectively and outperforms the existing methods.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1361-6"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1361","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24770443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
TCP-Rab: a receiver advertisement based TCP protocol. TCP- rab:基于接收方通告的TCP协议。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1352
Xu-hong Tang, Zheng-lan Liu, Miao-liang Zhu
{"title":"TCP-Rab: a receiver advertisement based TCP protocol.","authors":"Xu-hong Tang,&nbsp;Zheng-lan Liu,&nbsp;Miao-liang Zhu","doi":"10.1631/jzus.2004.1352","DOIUrl":"https://doi.org/10.1631/jzus.2004.1352","url":null,"abstract":"<p><p>With the evolution of network technologies, the deficiencies of TCP protocol are becoming more and more distinct. The new TCP implementation, called Receiver Advertisement Based TCP (TCP-Rab) proposed here to eliminate these deficiencies, adopts two basic mechanisms: (1) Bandwidth Estimation and (2) Immediate Recovery. Bandwidth estimation is carried out at the receiver, and the result is sent back to the sender via the acknowledgements. Immediate Recovery guarantees high performance even in lossy link. Rab can distinguish the reason for packet loss, and thus adopt appropriate recovery strategy. For loss by network congestion, it will back off its congestion window, and for loss by link errors, it will recover the congestion window immediately. Simulations indicated that Rab has superiority over other TCP implementations.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1352-60"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1352","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24771062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
A modified multitarget adaptive array algorithm for wireless CDMA system. 一种改进的无线CDMA系统多目标自适应阵列算法。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1418
Yun-hui Liu, Yu-hang Yang
{"title":"A modified multitarget adaptive array algorithm for wireless CDMA system.","authors":"Yun-hui Liu,&nbsp;Yu-hang Yang","doi":"10.1631/jzus.2004.1418","DOIUrl":"https://doi.org/10.1631/jzus.2004.1418","url":null,"abstract":"<p><p>The paper presents a modified least squares despread respread multitarget constant modulus algorithm (LS-DRMTCMA). The cost function of the original algorithm was modified by the minimum bit error rate (MBER) criterion. The novel algorithm tries to optimize weight vectors by directly minimizing bit error rate (BER) of code division multiple access (CDMA) mobile communication system. In order to achieve adaptive update of weight vectors, a stochastic gradient adaptive algorithm was developed by a kernel density estimator of possibility density function based on samples. Simulation results showed that the modified algorithm remarkably improves the BER performance, capacity and near-far effect resistance of a given CDMA communication system.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1418-23"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1418","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24771507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
A scalable admission control scheme based on time label. 一种基于时间标签的可扩展准入控制方案。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1424
Song-an Yang, Hua Yang, Yu-hang Yang
{"title":"A scalable admission control scheme based on time label.","authors":"Song-an Yang,&nbsp;Hua Yang,&nbsp;Yu-hang Yang","doi":"10.1631/jzus.2004.1424","DOIUrl":"https://doi.org/10.1631/jzus.2004.1424","url":null,"abstract":"<p><p>Resource reservation protocols allow communicating hosts to reserve resources such as bandwidth to offer guaranteed service. However, current resource reservation architectures do not scale well for a large number of flows. In this paper, we present a simple reservation protocol and a scalable admission control algorithm, which can provide QoS guarantees to individual flows without per-flow management in the network core. By mapping each flow to a definite time, this scheme addresses the problems that limit the effectiveness of current endpoint admission control schemes. The overall admission control process is described. Analysis is used to explain the reasonability of our scheme and simulation validates its performance.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1424-31"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1424","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24771508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Hierarchical planning for a surface mounting machine placement. 表面贴装机布局的分层规划。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1449
You-jiao Zeng, Deng-ze Ma, Ye Jin, Jun-qi Yan
{"title":"Hierarchical planning for a surface mounting machine placement.","authors":"You-jiao Zeng,&nbsp;Deng-ze Ma,&nbsp;Ye Jin,&nbsp;Jun-qi Yan","doi":"10.1631/jzus.2004.1449","DOIUrl":"https://doi.org/10.1631/jzus.2004.1449","url":null,"abstract":"<p><p>For a surface mounting machine (SMM) in printed circuit board (PCB) assembly line, there are four problems, e.g. CAD data conversion, nozzle selection, feeder assignment and placement sequence determination. A hierarchical planning for them to maximize the throughput rate of an SMM is presented here. To minimize set-up time, a CAD data conversion system was first applied that could automatically generate the data for machine placement from CAD design data files. Then an effective nozzle selection approach implemented to minimize the time of nozzle changing. And then, to minimize picking time, an algorithm for feeder assignment was used to make picking multiple components simultaneously as much as possible. Finally, in order to shorten pick-and-place time, a heuristic algorithm was used to determine optimal component placement sequence according to the decided feeder positions. Experiments were conducted on a four head SMM. The experimental results were used to analyse the assembly line performance.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1449-55"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1449","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24771511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Feature selection based on mutual information and redundancy-synergy coefficient. 基于互信息和冗余协同系数的特征选择。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1382
Sheng Yang, Jun Gu
{"title":"Feature selection based on mutual information and redundancy-synergy coefficient.","authors":"Sheng Yang,&nbsp;Jun Gu","doi":"10.1631/jzus.2004.1382","DOIUrl":"https://doi.org/10.1631/jzus.2004.1382","url":null,"abstract":"<p><p>Mutual information is an important information measure for feature subset. In this paper, a hashing mechanism is proposed to calculate the mutual information on the feature subset. Redundancy-synergy coefficient, a novel redundancy and synergy measure of features to express the class feature, is defined by mutual information. The information maximization rule was applied to derive the heuristic feature subset selection method based on mutual information and redundancy-synergy coefficient. Our experiment results showed the good performance of the new feature selection method.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1382-91"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1382","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24770446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
How to realize a negative refractive index material at the atomic level in an optical frequency range? 如何在光学频率范围内实现原子水平上的负折射率材料?
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1322
Jian-qi Shen, Zhi-chao Ruan, Sai-ling He
{"title":"How to realize a negative refractive index material at the atomic level in an optical frequency range?","authors":"Jian-qi Shen,&nbsp;Zhi-chao Ruan,&nbsp;Sai-ling He","doi":"10.1631/jzus.2004.1322","DOIUrl":"https://doi.org/10.1631/jzus.2004.1322","url":null,"abstract":"<p><p>The theoretical mechanism for realizing a negative refractive index material in an optical frequency range with an atomic gas system of electromagnetically induced transparency (EIT) is studied. It is shown that under certain conditions such a dense gas can exhibit simultaneously negative permittivity and negative permeability, and negligibly small loss.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1322-6"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1322","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24771058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 47
A novel OFDM transmission scheme with length-adaptive Cyclic Prefix. 一种新的长度自适应循环前缀OFDM传输方案。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1336
Li-feng Lai, Zhao-yang Zhang
{"title":"A novel OFDM transmission scheme with length-adaptive Cyclic Prefix.","authors":"Li-feng Lai,&nbsp;Zhao-yang Zhang","doi":"10.1631/jzus.2004.1336","DOIUrl":"https://doi.org/10.1631/jzus.2004.1336","url":null,"abstract":"<p><p>Conventional OFDM transmission system uses a fixed-length Cyclic Prefix to counteract Inter-Symbol Interferences (ISI) caused by channel delay spreading under wireless mobile environment. This may cause considerable performance deterioration when the CP length is less than the channel RMS delay spread, or may decrease the system power and spectrum efficiency when it is much larger. A novel OFDM transmission scheme is proposed in this paper to adapt the CP length to the variation of channel delay spread. AOFDM-VCPL utilizes the preamble or pilot sub-carriers of each OFDM packet to estimate the channel RMS delay spread; and then uses a criterion to calculate the CP length , which finally affects the OFDM transmitter. As illustrated in the simulation section, by deploying this scheme in a typical wireless environment, the system can transmit at data rate 11.5 Mb/s higher than conventional non-adaptive system while gaining a 0.65 dB power saving at the same BER performance.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1336-42"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24771060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Model-based testing with UML applied to a roaming algorithm for bluetooth devices. 基于模型的UML测试应用于蓝牙设备的漫游算法。
Journal of Zhejiang University. Science Pub Date : 2004-11-01 DOI: 10.1631/jzus.2004.1327
Zhen Ru Dai, Jens Grabowski, Helmut Neukirchen, Holger Pals
{"title":"Model-based testing with UML applied to a roaming algorithm for bluetooth devices.","authors":"Zhen Ru Dai,&nbsp;Jens Grabowski,&nbsp;Helmut Neukirchen,&nbsp;Holger Pals","doi":"10.1631/jzus.2004.1327","DOIUrl":"https://doi.org/10.1631/jzus.2004.1327","url":null,"abstract":"<p><p>In late 2001, the Object Management Group issued a Request for Proposal to develop a testing profile for UML 2.0. In June 2003, the work on the UML 2.0 Testing Profile was finally adopted by the OMG. Since March 2004, it has become an official standard of the OMG. The UML 2.0 Testing Profile provides support for UML based model-driven testing. This paper introduces a methodology on how to use the testing profile in order to modify and extend an existing UML design model for test issues. The application of the methodology will be explained by applying it to an existing UML Model for a Bluetooth device.</p>","PeriodicalId":85042,"journal":{"name":"Journal of Zhejiang University. Science","volume":"5 11","pages":"1327-35"},"PeriodicalIF":0.0,"publicationDate":"2004-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1631/jzus.2004.1327","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24771059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
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