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Gated Neural Network-Based Unsteady Aerodynamic Modeling for Large Angles of Attack
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作者 DENG Yongtao CHENG Shixin MI Baigang 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第4期432-443,共12页
Modeling of unsteady aerodynamic loads at high angles of attack using a small amount of experimental or simulation data to construct predictive models for unknown states can greatly improve the efficiency of aircraft ... Modeling of unsteady aerodynamic loads at high angles of attack using a small amount of experimental or simulation data to construct predictive models for unknown states can greatly improve the efficiency of aircraft unsteady aerodynamic design and flight dynamics analysis.In this paper,aiming at the problems of poor generalization of traditional aerodynamic models and intelligent models,an intelligent aerodynamic modeling method based on gated neural units is proposed.The time memory characteristics of the gated neural unit is fully utilized,thus the nonlinear flow field characterization ability of the learning and training process is enhanced,and the generalization ability of the whole prediction model is improved.The prediction and verification of the model are carried out under the maneuvering flight condition of NACA0015 airfoil.The results show that the model has good adaptability.In the interpolation prediction,the maximum prediction error of the lift and drag coefficients and the moment coefficient does not exceed 10%,which can basically represent the variation characteristics of the entire flow field.In the construction of extrapolation models,the training model based on the strong nonlinear data has good accuracy for weak nonlinear prediction.Furthermore,the error is larger,even exceeding 20%,which indicates that the extrapolation and generalization capabilities need to be further optimized by integrating physical models.Compared with the conventional state space equation model,the proposed method can improve the extrapolation accuracy and efficiency by 78%and 60%,respectively,which demonstrates the applied potential of this method in aerodynamic modeling. 展开更多
关键词 large angle of attack unsteady aerodynamic modeling gated neural networks generalization ability
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基于惩罚函数的混合专家模型参数训练方法
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作者 朱友忠 叶世伟 陈宜成 《计算机仿真》 CSCD 2005年第5期202-206,共5页
混合专家模型是将一个问题的输入空间适当地分解为多个不同的区域,一个区域用一个专家网络来映射,然后再用一个门网协调专家,去决定专家网络的输出。基于惩罚函数的混合专家模型利用了凸函数共轭性质中的Fenchel不等式,构造带有约束项... 混合专家模型是将一个问题的输入空间适当地分解为多个不同的区域,一个区域用一个专家网络来映射,然后再用一个门网协调专家,去决定专家网络的输出。基于惩罚函数的混合专家模型利用了凸函数共轭性质中的Fenchel不等式,构造带有约束项的优化目标函数,这个目标函数单独对于权值和隐层输出来说均为凸函数,优化时不存在局部最小,因此,优化速度快,大大提高了混合专家网络的学习效率。数值实验表明,该方法较传统的梯度下降方法效果好。 展开更多
关键词 混合专家 凸优化 全局最优解 门网协调专家
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利用二阶网络和判别分析建立分层混合专家模型
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作者 张继宾 曹柳林 《鞍山科技大学学报》 2007年第4期350-354,共5页
利用多层二阶神经元网络快速收敛及逼近连续函数的良好性质,并结合判别分析思想,构建了一种新的分层混合专家结构模型。这种结构模型选用二阶网络作为专家模块,可调权值数量适中,收敛速度快;它首次引入判别分析统计方法,并借鉴模块化设... 利用多层二阶神经元网络快速收敛及逼近连续函数的良好性质,并结合判别分析思想,构建了一种新的分层混合专家结构模型。这种结构模型选用二阶网络作为专家模块,可调权值数量适中,收敛速度快;它首次引入判别分析统计方法,并借鉴模块化设计理念,构建了无训练参数的组合门网模块。专家和门网模块的改进与设计,从根本上降低了分层混合专家网络的训练难度,提高了网络的训练速度和泛化能力。对典型非线性pH值混合槽实例进行了实验,结果表明,在相同的终止条件下,与目前常用的结构模型相比,新型结构模型的收敛速度和泛化能力都得到了显著的提高,验证了新模型在函数逼近应用中的良好特性。 展开更多
关键词 二阶神经元网络 判别分析法 分层混合专家 专家 门网
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Portal biliopathy 被引量:10
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作者 Somnath Chattopadhyay Samiran Nundy 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第43期6177-6182,共6页
Biliary ductal changes are a common radiological finding in patients with portal hypertension, however only a small percentage of patients (5%-30%) develop symptomatic bile duct obstruction. The exact pathogenesis is ... Biliary ductal changes are a common radiological finding in patients with portal hypertension, however only a small percentage of patients (5%-30%) develop symptomatic bile duct obstruction. The exact pathogenesis is not clear, but an involvement of factors such as bile duct compression by venous collaterals, ischemia, and infection is accepted by most authors. Although endoscopic retrograde cholangiopancrea- tography was used to define and diagnose this condition, magnetic resonance cholangiopancreatography is currently the investigation of choice for diagnosing this condition. Treatment is indicated only for symptomatic cases. Portosystemic shunts are the treatment of choice for symptomatic portal biliopathy. In the majority of patients, the changes caused by biliopathy resolve after shunt surgery, however, 15%-20% patients require a subsequent bilio-enteric bypass or endoscopic management for persistent biliopathy. There is a role for endoscopic therapy in patients with bile duct stones, cholangitis or when portosystemic shunt surgery is not feasible. 展开更多
关键词 Pseudosclerosing cholangitis Non cirrhotic portal fibrosis Extrahepatic portal venous obstruction Proximal lienorenal shunt Biliary obstruction Portal cavernoma
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Acute extensive portal and mesenteric venous thrombosis after splenectomy:Treated by interventional thrombolysis with transjugular approach 被引量:8
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作者 Mao-Qiang Wang Han-Ying Lin Li-Ping Guo Feng-Yong Liu Feng Duan Zhi-Jun Wang 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第24期3038-3045,共8页
AIM:To present a series of cases with symptomatic acute extensive portal vein(PV)and superior mesenteric vein(SMV)thrombosis after splenectomy treated by transjugular intrahepatic approach catheter-directed thrombolys... AIM:To present a series of cases with symptomatic acute extensive portal vein(PV)and superior mesenteric vein(SMV)thrombosis after splenectomy treated by transjugular intrahepatic approach catheter-directed thrombolysis. METHODS:A total of 6 patients with acute extensive PV-SMV thrombosis after splenectomy were treated by transjugular approach catheter-directed thrombolysis. The mean age of the patients was 41.2 years.After access to the portal system via the transjugular approach,pigtail catheter fragmentation of clots, local urokinase injection,and manual aspiration thrombectomy were used for the initial treatment of PV-SMV thrombosis,followed by continuous thrombolytic therapy via an indwelling infusion catheter in the SMV,which was performed for three to six days. Adequate anticoagulation was given during treatment, throughout hospitalization,and after discharge. RESULTS:Technical success was achieved in all 6 patients.Clinical improvement was seen in these patients within 12-24 h of the procedure.No complications were observed.The 6 patients were discharged 6-14 d(8±2.5 d)after admission.The mean duration of follow-up after hospital discharge was 40±16.5 mo.Ultrasound and contrast-enhanced computed tomography confirmed patency of the PV and SMV,and no recurrent episodes of PV-SMV thrombosis developed during the follow-up period. CONCLUSION:Catheter-directed thrombolysis via transjugular intrahepatic access is a safe and effective therapy for the management of patients with symptomatic acute extensive PV-SMV thrombosis. 展开更多
关键词 Mechanical thrombectomy Portal vein SPLENECTOMY Superior mesenteric vein THROMBOLYSIS THROMBOSIS
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Portal vein cannulation:An uncommon complication of endoscopic retrograde cholangiopancreatography 被引量:3
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作者 Evangelos Kalaitzakis Nicholas Stern Richard Sturgess 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第46期5131-5132,共2页
Portal vein cannulation is a rare complication of endo-scopic retrograde cholangiopancreatography(ERCP).It has been reported that it usually occurs after endo-scopic sphincterotomy,whereas in cases without prior sphin... Portal vein cannulation is a rare complication of endo-scopic retrograde cholangiopancreatography(ERCP).It has been reported that it usually occurs after endo-scopic sphincterotomy,whereas in cases without prior sphincterotomy,the presence of portobiliary fistulas has been shown.Here,we present a case in which cannulation of the portal vein occurred despite careful wire-guided cannulation and the absence of sphinc-terotomy.Although fatal cases of cerebral and pulmo-nary air and/or bile embolism have been reported in patients with combined portal and hepatic vein trauma after ERCP and sphincterotomy,isolated portal vein cannulation,as in the current case,does not usu-ally result in mortality or serious morbidity.However,awareness of this rare complication is important so that no further intervention is performed. 展开更多
关键词 Endoscopic retrograde cholangiopancrea-tography Complications Portal vein cannulation
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Protein interaction network related to Helicobacter pylori infection response 被引量:8
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作者 Kyu Kwang Kim Han Bok Kim 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第36期4518-4528,共11页
AIM:To understand the complex reaction of gastric inflammation induced by Helicobacter pylori(H pylori) in a systematic manner using a protein interaction network. METHODS:The expression of genes significantly changed... AIM:To understand the complex reaction of gastric inflammation induced by Helicobacter pylori(H pylori) in a systematic manner using a protein interaction network. METHODS:The expression of genes significantly changed on microarray during H pylori infection was scanned from the web literary database and translated into proteins.A network of protein interactions was constructed by searching the primary interactions of selected proteins.The constructed network was mathematically analyzed and its biological function was examined.In addition,the nodes on the network were checked to determine if they had any further functional importance or relation to other proteins by extending them. RESULTS:The scale-free network showing the relationship between inflammation and carcinogenesis was constructed.Mathematical analysis showed hub and bottleneck proteins,and these proteins were mostly related to immune response.The network contained pathways and proteins related to H pylori infection,such as the JAK-STAT pathway triggered by interleukins.Activation of nuclear factor (NF)-κB,TLR4,and other proteins known to function as core proteins of immune response were also found. These immune-related proteins interacted on the network with pathways and proteins related to the cell cycle,cell maintenance and proliferation,andtranscription regulators such as BRCA1,FOS,REL,and zinc finger proteins.The extension of nodes showed interactions of the immune proteins with cancer- related proteins.One extended network,the core network,a summarized form of the extended network, and cell pathway model were constructed. CONCLUSION:Immune-related proteins activated by H pylori infection interact with proto-oncogene proteins.The hub and bottleneck proteins are potential drug targets for gastric inflammation and cancer. 展开更多
关键词 Gastric cancer Helicobacter pylori INFLAMMATION PATHWAY Protein interaction network
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Design and Construction of Composite Tubular Arches with Network Suspension System: Recent Undertakings and Trends 被引量:1
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作者 Francisco Millanes Mato Miguel Ortega Comejo Jorge Nebreda Sanchez 《Journal of Civil Engineering and Architecture》 2011年第3期191-214,共24页
The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkabl... The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkable reduction of bending stresses in the arches and tie beams. The present paper describes the main features of the design and construction of several long-span arch bridges of this typology in Spain: the three pedestrian footbridges for the Madrid cycling ring track, with spans of 52, 60 and 80 m, the Bridge over River Deba in Guipuzcoa with a span of 110 m and Palma del Rio Bridge over River Guadalquivir in Cordoba, 130 m long. In all cases, two inclined arches linked at the crown were implemented, a very effective disposition to reduce the out-of-plane buckling length. The multiple crossings of the hanger system, consisting of prestressed bars in the case of Deba Bridge and the footbridges, and locked coil cables for Palma del Rio Bridge, were dealt with by means of crossing devices which led to a technically satisfactory solution with minimal visual impact. An innovative approach to bowstring arches was introduced in Valdebebas Bridge over M-12 motorway in Madrid, next to the new T-4 Terminal of Barajas Airport, with a span of 162 m, where the hangers are replaced by a structural steel mesh -diagrid- which acts as the web of a simply-supported beam whose compression head is the arch and the tie beam is the deck. 展开更多
关键词 Bowstring arch network system hangers crossing devices composite bridge diagrid
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URI Online Judge: A New Interactive Learning Approach
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作者 Neilor Avelino Tonin Jean Luca Bez 《Computer Technology and Application》 2013年第1期34-38,共5页
The URI online judge is a new online tool created with the main purpose of making programming practice more dynamic, interesting and stimulating for those who have just entered into the art of programming. The URI onl... The URI online judge is a new online tool created with the main purpose of making programming practice more dynamic, interesting and stimulating for those who have just entered into the art of programming. The URI online judge allows problem corrections in real time, interactivity between users, besides it allows flexibility in the choice of the programming language and it makes some supporting materials available. During the short time in which the tool has being used we have observed that it is a very good tool for self-study. As users of programming portals, the authors noticed some details that would be important to be implemented in a new tool, such as the separation of problems by categories. Another fundamental detail is the fact that this tool is available in two languages (Portuguese and English). This might facilitate the learning process for beginners, both locally and globally. 展开更多
关键词 Classroom tool programming practice online judge informatics interactive learning.
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Employment Creation and Investment Attraction by Means of the Internet Portal of Puebla (Mexico) Government
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作者 Juan Carlos Botello Osorio 《Computer Technology and Application》 2011年第9期698-704,共7页
Some transactional governmental services are now offered to citizens world-wide by means of the internet. Principally, these transactions consist of applications for birth certificates, tax payments, payments of fines... Some transactional governmental services are now offered to citizens world-wide by means of the internet. Principally, these transactions consist of applications for birth certificates, tax payments, payments of fines, however, very rarely, or never can someone incorporate a business by means of e-government services. Rare also, are cases in which the consequences of business incorporation can be evaluated through the internet--for example employment creation or the attraction of investments. With respect to business incorporation the internet portal of the government of the state of Puebla is of no help, since it must be done in person in every case. 展开更多
关键词 Investment electronic government EMPLOYMENT business INCORPORATE
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Tools for Protein Structure Prediction at the bri-shur.com Web Portal
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作者 Sergey Feranchuk Ulyana Potapova +3 位作者 Vladimir Potapov Dmitry Mukha Vladimir Nikolaev Sergei Belikov 《Journal of Life Sciences》 2012年第10期1174-1179,共6页
lntemet services on bioinformatics still remain a popular tool for the researchers. Here the authors present a recently developed web-site http://bri-shur.com where several tools and pipelines for protein structure p... lntemet services on bioinformatics still remain a popular tool for the researchers. Here the authors present a recently developed web-site http://bri-shur.com where several tools and pipelines for protein structure prediction are implemented. The prediction of a structure for a particular protein often requires a sensitive and iterative approach, and the web-site provides an environment for this kind of work. Software that is used in the services includes both free programs available in the Internet and newly developed algorithms. The service on homology screening in PDB for a structure template is implemented using an approach that is alternative to well-known BLAST algorithm and it has some advantages over BLAST. The service on homology modeling uses well-known Nest program. The service on protein energy estimate allows selecting a best template in the set of homologs and adds a functionality of fold recognition to the environment. The design of the site simplifies several of the most useful bioinformatics routines, thus making them available to a large community of researchers. Services are provided free of charge without registration, and the user's privacy is taken care of. 展开更多
关键词 Web-service SOAP homology modeling homology screening protein folding.
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Analyzing gravity anomaly variations before the 2016 Ms6.4 earthquake in Menyuan,Qinghai with an interpolation/cutting potential field separation technique 被引量:1
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作者 Liu Jin-Zhao Wang Tong-Qing +3 位作者 Chen Zhao-Hui Zhang Pin Zhu Chuan-Dong and Zhang Shuang-Xi 《Applied Geophysics》 SCIE CSCD 2018年第1期137-146,150,共11页
We evaluated 2011-2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characterist... We evaluated 2011-2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characteristics of the gravity field at the focal depth. In addition, we assessed the regional gravity field and its variation the half-year before the earthquake. We use first different interpolation algorithms to build a grid for the gravity data and then introduce potential field interpolation-cutting separation techniques and adaptive noise filtering. The results suggest that the gravity filed at the focal depth of 11.12 km separated from the total gravity field at about -400-150 ×10^-8 m/s^2 in the second half of 2015, which is larger than that in the same period in 2011 to 2014 (±30×10^-8 m/s^2). Moreover, at the same time, the gravity field changed fast from September 2014 to May 2015 and May 2015 to September 2015, reflecting to some extent material migration deep in the crust before the Menyuan earthquake. 展开更多
关键词 Menyuan EARTHQUAKE GRIDDING DENOISING potential field separation
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Turnout fault prediction method based on gated recurrent units model
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作者 ZHANG Guorui SI Yongbo +1 位作者 CHEN Guangwu WEI Zongshou 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2021年第3期304-313,共10页
Turnout is one of the important signal infrastructure equipment,which will directly affect the safety and efficiency of driving.Base on analysis of the power curve of the turnout,we extract and select the time domain ... Turnout is one of the important signal infrastructure equipment,which will directly affect the safety and efficiency of driving.Base on analysis of the power curve of the turnout,we extract and select the time domain and Haar wavelet transform characteristics of the curve firstly.Then the correlation between the degradation state and the fault state is established by using the clustering algorithm and the Pearson correlation coefficient.Finally,the convolutional neural network(CNN)and the gated recurrent unit(GRU)are used to establish the state prediction model of the turnout to realize the failure prediction.The CNN can directly extract features from the original data of the turnout and reduce the dimension,which simplifies the prediction process.Due to its unique gate structure and time series processing features,GRU has certain advantages over the traditional forecasting methods in terms of prediction accuracy and time.The experimental results show that the accuracy of prediction can reach 94.2%when the feature matrix adopts 40-dimensional input and iterates 50 times. 展开更多
关键词 TURNOUT CLUSTERING convolutinal neural network(CNN) gated recurrent unit(GRU) fault prediction
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Development of Bioinfo-Portal Tool for the Analysis of Genomic and Proteomic Data
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作者 Rana Rehan Khalid Bilal Hussain +3 位作者 Muhammad Ali Muhammad Sajjad Ahmad Asma Haque Hira Qamar 《Journal of Life Sciences》 2012年第5期485-488,共4页
The recent explosion of biological data and the concomitant proliferation of distributed databases make it challenging for biologists and bioinformaticians to discover the best data resources for their needs, and the ... The recent explosion of biological data and the concomitant proliferation of distributed databases make it challenging for biologists and bioinformaticians to discover the best data resources for their needs, and the most efficient way to access and use them For the biologist, running bioinformatics analyses involve a time-consuming management of data and tools. Users need support to organize their work, retrieve parameters and reproduce their analyses. They also need to be able to combine their analytic tools using a safe data flow software mechanism. Finally we have designed a system, Bioinfo-Portal, to provide a flexible and usable web environment for defining and running bioinformatics analyses. It embeds simple yet powerful data management features that allow the user to reproduce analyses and to combine tools using an adobe flex tool. Bioinfo-Portal can also act as a front end to provide a unified view of already-existing collections of bioinformatics resources. Users can analyze genomic and proteomic data by using the tools that has been integrated in the portal (tools for alignments, dotplots, motif detection, domain analysis, profile searching and tertiary structure prediction). The sequences that user obtained from portal's nucleotide and protein databases are easily analyzed by the portal tools on the same interface in no time. User can also take benefit from the animations. 展开更多
关键词 Bioinfo-Portal analytic tools flexible and usable web environment tertiary structure prediction domain analysis motifdetection alignments.
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Research on the Contextual and Functional Differences Between New and Old Journalism
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作者 Cem S. Sutcu Murat Oztermiyeci 《Journalism and Mass Communication》 2011年第1期48-56,共9页
Mass Communication media were widespread in 19th and 20th centuries. Those technologies created by humans have had a big impact on both daily and business lives. Newspapers, Radio, TV and Cinema are obvious examples o... Mass Communication media were widespread in 19th and 20th centuries. Those technologies created by humans have had a big impact on both daily and business lives. Newspapers, Radio, TV and Cinema are obvious examples of this impact. Dinting the last two decades of 20th century, spread of personal computers transformed the way people live0 work and think. Some people evaluated the situation as revolution and others as threat to humans. Intemet, in this respect, is considered as mass media. People connect the Internet without time and space limitations. However, communication on the Internet is not mass commtmication because it requires every individual or organization to have a unique Intemet Protocol address (IP) to commtmicate. Because of its peer to peer communication nature just as in the telephone communication, this feature distinguishes Intemet from other commtmication media. On the other hand, it resembles mass communication media because of its mobility, spread and functionality both for sender and receiver. In many sectors, including communication and information technology sectors, mobility, spread and functionality features lead the way to increase interactivity between parties in communication. Businesses benefited the "interactivity tool" for many purposes: to increase market share for a product or service, to increase customer satisfaction, or to increase amount of information about their customers, competitors or suppliers in order to make strategic decisions. For journalism and generally, for mass media, interactivity is an important aspect of the business. Media corporations must know the needs of their audience before they express and take precautionary steps to satisfy them. This forces the mass media sector to increase interactivity in customer communication. In this paper, we researched the intemctivity effect in journalism that we see especially in internet journalism applications. The research aims to cover opinions of newspapers, advertisers and audience on interactivity and future of mass media communication. For this purpose, fmdings of a survey have been evaluated. 展开更多
关键词 new media mteractivity intemet journalism
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Synchronization of a Class of Delayed Neural Networks with Sector Nonlinearity 被引量:3
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作者 HUANG You-liang 《Chinese Quarterly Journal of Mathematics》 CSCD 2010年第1期124-131,共8页
In this paper, global synchronization is discussed for a general class of delayed neural networks with time-varying and distributed delays. Furthermore, the activation func- tions in the neural networks can be differe... In this paper, global synchronization is discussed for a general class of delayed neural networks with time-varying and distributed delays. Furthermore, the activation func- tions in the neural networks can be different type. Based on the drive-response concept and the Lyapunov stability theorem, some sufficient criteria are obtained to guarantee the global synchronization of the considered models even when input sector nonlinearity caused by physical limitations is presented in response systems. Finally, a typical example is also given to illustrate the effectiveness of the proposed synchronization scheme. 展开更多
关键词 SYNCHRONIZATION neural networks distributed delays sector nonlinearity
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The Theory of Internet Finance 被引量:9
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作者 谢平 邹传伟 《China Economist》 2013年第2期18-26,共9页
Internet based technologies, such as mobile payments, social networks, search engines and cloud computation, will lead to a paradigm shift in financial sector. Beside indirect financing via commercial banks and direct... Internet based technologies, such as mobile payments, social networks, search engines and cloud computation, will lead to a paradigm shift in financial sector. Beside indirect financing via commercial banks and direct financing through security markets, a third way to conduct financial activities will emerge, which we call "internet finance'" This paper presents a detailed analysis of payment, information processing and resource allocation under internet finance. 展开更多
关键词 internet finance mobile payments social networks search engines cloudcomputation
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Smart Home Based on Wireless Sensor-Actuator Networks 被引量:6
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作者 孙岩 陈强 罗红 《China Communications》 SCIE CSCD 2011年第1期102-109,共8页
Wireless sensor-actuator networks can bring flexibility to smart home.We design and develop a smart home prototype using wireless sensor-actuator network technology to realize environmental sensing and the control of ... Wireless sensor-actuator networks can bring flexibility to smart home.We design and develop a smart home prototype using wireless sensor-actuator network technology to realize environmental sensing and the control of electric appliances.The basic motivation of our solution is to utilize the collaboration among a mass of low-cost sensor nodes and actuator nodes to make life convenient.To achieve it,we design a novel system architecture with assembled component modules.In particular,we address some key technical challenges:1) Field-Programmable Gate Array (FPGA) Implementation of Adaptive Differential Pulse Code Modulation (ADPCM) for audio data;2) FPGA Implementation of Lempel Ziv Storer Szymanski (LZSS) for bulk data;3) combination of complex control logic.Finally,a set of experiments are presented to evaluate the performance of our solution. 展开更多
关键词 smart home sensor-actuator network FPGA
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Joint subcarrier and power allocation with threshold in cooperative multiuser networks 被引量:1
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作者 Tang Mingwei Wang Xiaoxiang 《High Technology Letters》 EI CAS 2011年第4期360-365,共6页
In this paper, we investigate a resource allocation issue in OFDMA-based decode-and-forward cooperative multiuser networks and propose joint subcarrier and power allocation schemes. The optimal solution of this combin... In this paper, we investigate a resource allocation issue in OFDMA-based decode-and-forward cooperative multiuser networks and propose joint subcarrier and power allocation schemes. The optimal solution of this combinable allocation shows high computational complexity, so we allocate subcarriers and power separately. At firstly, we distribute subcarriers to relays and users under the assumption of equal power distribution. Here, we propose an equal capacity increment (ECI) allocation strategy to achieve tradeoff between total throughput and fairness. To further improve the system performance, we introduce threshold into ECI strategy, named ECI strategy with threshold (ECI-T), where subcarriers with bad performance are prevented from transmitting. Subsequently, a water-filling method is adopted to distribute the power to cooperative links in order to fully utilize the limited power. Simulation results show that system performance of the proposed schemes is significantly enhanced compared with an existing resource allocation scheme. Besides, the resource allocation schemes with the water- filling method notably outperform schemes with equal power allocation. 展开更多
关键词 cooperative communication orthogonal ~equency division multiplexing access (OFDMA) resource allocation THRESHOLD
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Towards Wide-Open, Adaptable DCF Implementation for Dynamic Networks 被引量:2
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作者 Wang Shan Abdelhakim Hafid +3 位作者 Zhao Haitao Huang Shengchun Xieng Chunlin Wei Jibo 《China Communications》 SCIE CSCD 2012年第7期77-89,共13页
Abstract: This work proposes a Field Programmable Gate Array (FPGA)-oriented architecture for the IEEE 802.11 Distributed Coordination Function (DCF) transceiver. We describe the functional blocks carrying out th... Abstract: This work proposes a Field Programmable Gate Array (FPGA)-oriented architecture for the IEEE 802.11 Distributed Coordination Function (DCF) transceiver. We describe the functional blocks carrying out the Carrier Sense Multiple Accesses with Collision Avoidance (CSMA/CA), develop the interfaces to the application layer and the physical layer, and implement it on FPGA devices by utilizing Very-high-speed-integrated-circuit Hardware Description Language (VHDL). 展开更多
关键词 wireless networks DCF adaptation capability FPGA CSM A/CA cognitive networks
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