期刊文献+
共找到35篇文章
< 1 2 >
每页显示 20 50 100
一个集组计数问题的简证
1
作者 王景周 崔建英 《中等数学》 2004年第1期18-18,共1页
关键词 计数 数学归纳法 容斥原理
下载PDF
矽钢片冲制监视计数集控装置
2
作者 郭国平 何士林 《微型电脑应用》 1991年第3期140-148,共9页
关键词 矽钢片 冲片 计数控装置 冲制
下载PDF
综合运输体系下的货运方式分担率 被引量:14
3
作者 项昀 王炜 +3 位作者 王昊 李烨 郑敦勇 刘兵 《东南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2015年第6期1197-1202,共6页
为优化货运交通结构并合理配置货运交通资源,研究了综合运输体系下基于运距的货运方式分担率.通过对国内城市间不同货运量与运距的集计数据进行统计分析,确定货运量与运距的函数关系式.随后,构建货运方式分担率-运距模型,并获取货运方... 为优化货运交通结构并合理配置货运交通资源,研究了综合运输体系下基于运距的货运方式分担率.通过对国内城市间不同货运量与运距的集计数据进行统计分析,确定货运量与运距的函数关系式.随后,构建货运方式分担率-运距模型,并获取货运方式分担率-运距曲线.研究结果表明,各货运方式分担率随运距变化呈现出特定的分布规律.公路货运分担率-运距曲线呈单调递减趋势,在50~500 km运距范围内的分担率超过40%;铁路货运分担率-运距曲线呈先增后减趋势,拐点出现在600~700 km之间;水路货运分担率-运距曲线呈单调递增趋势;航空货运分担率-运距曲线在150~700 km运距范围内呈缓慢递增趋势,700~1 900 km运距范围内快速递增,运距超过1 900 km后趋于平缓. 展开更多
关键词 货运方式 分担率 运距 综合运输体系 集计数据
下载PDF
托运人货运服务选择行为模型研究述评 被引量:7
4
作者 张戎 陶学宗 《同济大学学报(自然科学版)》 EI CAS CSCD 北大核心 2013年第9期1384-1391,共8页
行为模型是货运需求分析的重要方法之一,能够很好地描述托运人的货运服务选择行为特征,预测不同货运服务的市场需求,因而在货运设施和政策措施的预期效果评估方面得到了广泛应用.在对2000年以后46篇文献研究的基础上,根据货运非集计行... 行为模型是货运需求分析的重要方法之一,能够很好地描述托运人的货运服务选择行为特征,预测不同货运服务的市场需求,因而在货运设施和政策措施的预期效果评估方面得到了广泛应用.在对2000年以后46篇文献研究的基础上,根据货运非集计行为模型的研究主题对其进行归类整理,分析货运非集计行为模型的理论基础、建模思路和数据来源,并从货运服务选择影响因素识别、货运服务潜在市场份额预测、货运服务质量属性价值估算等三个方面对货运非集计行为模型的研究方法和结论进行述评.最后,讨论了既有研究存在的不足和未来进一步研究的方向. 展开更多
关键词 综合运输 货运建模 随机效用理论 货运选择行为 集计数据
下载PDF
嵌入式软件测试平台配置 被引量:2
5
作者 刘久富 孙德敏 《工业控制计算机》 2004年第12期41-42,55,共3页
本文总结了建立软件评测中心必要条件,论述了软件测试过程并给出了各阶段的软件测试工具。在对市场充分调研的基础上,结合嵌入式软件的技术特点及具体工作需求,构建了一个嵌入式软件测试平台。
关键词 嵌入式软件 软件测试过程 测试平台 软件测试工具 配置 技术特点 必要条件 软件评测 市场 调研
下载PDF
Automatic relational database compression scheme design based on swarm evolution 被引量:1
6
作者 HU Tian-lei CHEN Gang +1 位作者 LI Xiao-yan DONG Jin-xiang 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第10期1642-1651,共10页
Compression is an intuitive way to boost the performance of a database system. However, compared with other physical database design techniques, compression consumes large amount of CPU power. There is a trade-off bet... Compression is an intuitive way to boost the performance of a database system. However, compared with other physical database design techniques, compression consumes large amount of CPU power. There is a trade-off between the re- duction of disk access and the overhead of CPU processing. Automatic design and adaptive administration of database systems are widely demanded, and the automatic selection of compression schema to compromise the trade-off is very important. In this paper, we present a model with novel techniques to integrate a rapidly convergent agent-based evolution framework, i.e. the SWAF (SWarm Algorithm Framework), into adaptive attribute compression for relational database. The model evolutionally consults statistics of CPU load and IO bandwidth to select compression schemas considering both aspects of the trade-off. We have im- plemented a prototype model on Oscar RDBMS with experiments highlighting the correctness and efficiency of our techniques. 展开更多
关键词 Database compression Automatic physical database design Swarm evolution
下载PDF
A version management model of PDM system and its realization 被引量:2
7
作者 钟诗胜 李涛 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第4期459-464,共6页
Based on the key function of version management in PDM system, this paper discusses the function and the realization of version management and the transitions of version states with a workflow. A directed aeyclic grap... Based on the key function of version management in PDM system, this paper discusses the function and the realization of version management and the transitions of version states with a workflow. A directed aeyclic graph is used to describe a version model. Three storage modes of the directed acyelic graph version model in the database, the bumping block and the PDM working memory are presented and the conversion principle of these three modes is given. The study indicates that building a dynamic product structure configuration model based on versions is the key to resolve the problem. Thus a version model of single product object is built. Then the version management model in product structure configuration is built and the application of version management of PDM syster is presented as a case. 展开更多
关键词 product data management (PDM) version management directed acyclic graph version model product structure configuration management
下载PDF
Web-services-based Integration Design of PDM and DNC Systems 被引量:1
8
作者 周炳海 王世进 曹永上 《Journal of Donghua University(English Edition)》 EI CAS 2007年第1期30-34,共5页
In a networked manufacturing environment, product data integration is the foundation of collaborative manufacturing among manufacturing enterprises. It is very important to build an effective integration mechanism for... In a networked manufacturing environment, product data integration is the foundation of collaborative manufacturing among manufacturing enterprises. It is very important to build an effective integration mechanism for product data sharing of manufacturing enterprises in geographically dispersed, heterogeneous system platform. In order to integrate enterprise level product data management (PDM) system and shop floor level distributed numerical control (DNC) system, based on the description of Web services technology, a Web-services-based integration approach is presented for facilitating seamless sharing of product data between PDM and DNC systems in a networked manufacturing environment. In order to verify the validity of the proposed approach, an example-based integration development has been implemented with Java 2 Software Development Kit and Java Web Services Developer Pack in Windows 2000 Professional environment. 展开更多
关键词 Product data management Distributed numerical control Web services Information integration.
下载PDF
Regression-Based Artificial Neural Network Methodology in Response Surface Methodology 被引量:4
9
作者 何桢 肖粤翔 《Transactions of Tianjin University》 EI CAS 2004年第2期153-157,共5页
Response surface methodology (RSM) is an important tool for process parameter optimization, robust design and other quality improvement efforts. When the relationship between influential input variables and output res... Response surface methodology (RSM) is an important tool for process parameter optimization, robust design and other quality improvement efforts. When the relationship between influential input variables and output response is very complex, it’s hard to find the real response surface using RSM. In recent years artificial neural network(ANN) has been used in RSM. But the classical ANN does not work well under the constraints of real applications. An algorithm of regression-based ANN(R-ANN) is proposed in this paper, which is a supplement to the classical ANN methodology. It makes network closer to the response surface, so that training time is reduced and robustness is strengthened. The procedure of improving ANN by regressions is described and the comparisons among R-ANN,RSM and classical ANN are computed graphically in three examples. Our research shows that the R-ANN methodology is a good supplement to the RSM and classical ANN methodology, which can yield lower standard error of prediction under conditions that the scope of experiment is rigidly restricted. 展开更多
关键词 response surface methodology(RSM) artificial neural network(ANN) regression-based ANN
下载PDF
A Hierarchical Virus Immunization Method for Community Networks 被引量:1
10
作者 FU Cai LI Min ZHANG Yunhe ZOU Deqing HAN Lansheng 《China Communications》 SCIE CSCD 2014年第9期148-159,共12页
Due to the enormous harm of virus propagation,research regarding virus immunizations still absolutely necessary.In comparison to current researches,a new virus immunization method the hierarchical virus immunization m... Due to the enormous harm of virus propagation,research regarding virus immunizations still absolutely necessary.In comparison to current researches,a new virus immunization method the hierarchical virus immunization method(HVIM) for community networks is proposed.Based on the virus transmission dynamic model SusceptibleInfectious-Removed and SusceptibleRemoved(SIRSR),HVIM considered the influence of external factors on the spread of viruses and only needs a portion of the network structure to be able to carry out immunization.Another pro for HVIM is that it is scalable and suitable for parallel computing which is a requirement in the big data era.Finally,a simulation dataset and a real dataset were used to run experiments,and the results of simulation showed that HVIM obviously is superior to others on the aspect of immunity. 展开更多
关键词 Community Networks VirusPropagation SIRSR Model HierarchicalVirus Immunization Method (HVIM)
下载PDF
Reliability modeling of hydraulic system of drum shearer machine 被引量:8
11
作者 SEYED HADI Hoseinie MOHAMMAD Ataie +1 位作者 REZA Khalookakaei UDAY Kumar 《Journal of Coal Science & Engineering(China)》 2011年第4期450-456,共7页
The hydraulic system plays an important role in supplying power and its transition to other working parts of a coal shearer machine. In this paper, the reliability of the hydraulic system of a drum shearer was analyze... The hydraulic system plays an important role in supplying power and its transition to other working parts of a coal shearer machine. In this paper, the reliability of the hydraulic system of a drum shearer was analyzed. A case study was done in the Tabas Coal Mine in Iran for failure data collection. The results of the statistical analysis show that the time between failures (TBF) data of this system followed the 3-parameters Weibull distribution. There is about a 54% chance that the hydraulic system of the drum shearer will not fail for the first 50 h of operation. The developed model shows that the reliability of the hydraulic system reduces to a zero value after approximately 1 650 hours of operation. The failure rate of this system decreases when time increases. Therefore, corrective maintenance (run-to-t^ailure) was selected as the best maintenance strategy for it. 展开更多
关键词 reliability modeling hydraulic system drum shearer maintenance strategy
下载PDF
Comparison of total splenic artery embolization and partial splenic embolization for hypersplenism 被引量:23
12
作者 Xin-Hong He Jian-Jian Gu +5 位作者 Wen-Tao Li Wei-Jun Peng Guo-Dong Li Sheng-Ping Wang Li-Chao Xu Jun Ji 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第24期3138-3144,共7页
AIM:To evaluate whether total splenic artery embolization(TSAE) for patients with hypersplenism delivers better long-term outcomes than partial splenic embolization(PSE).METHODS:Sixty-one patients with hypersplenism e... AIM:To evaluate whether total splenic artery embolization(TSAE) for patients with hypersplenism delivers better long-term outcomes than partial splenic embolization(PSE).METHODS:Sixty-one patients with hypersplenism eligible for TSAE(n = 27,group A) or PSE(n = 34,group B) were enrolled into the trial,which included clinical and computed tomography follow-up.Data on technical success,length of hospital stay,white blood cell(WBC) and platelet(PLT) counts,splenic volume and complications were collected at 2 wk,6 mo,and 1,2,3,4 years postoperatively.RESULTS:Both TSAE and PSE were technically successful in all patients.Complications were significantly fewer(P = 0.001),and hospital stay significantly shorter(P = 0.007),in group A than in group B.Postprocedure WBC and PLT counts in group A were significantly higher than those in group B from 6 mo to 4 years(P = 0.001),and post-procedure residual splenic volume in group A was significantly less than that observed in group B at 1,2,3 and 4 years post-procedure(P = 0.001).No significant differences were observed in red blood cell counts and liver function parameters between the two groups following the procedure.CONCLUSION:Our results indicate that TSAE for patients with hypersplenism not only delivers a better longterm outcome,but is also associated with lower complication rates and a shorter hospital stay than PSE. 展开更多
关键词 EMBOLIZATION HYPERSPLENISM COMPLICATIONS White cell counts Platelet counts
下载PDF
AN IMPROVED GENETIC ALGORITHM FOR SEARCHING OPTIMAL PARAMETERS IN n-DIMENSIONAL SPACE
13
作者 Tang Bin Hu Guangrui(Department of Electronic Engineering, Shanghai Jiaotong University, Shanghai 200030) 《Journal of Electronics(China)》 2002年第2期218-219,共2页
An improved genetic algorithm for searching optimal parameters in n-dimensional space is presented, which encodes movement direction and distance and searches from coarse to precise. The algorithm can realize global o... An improved genetic algorithm for searching optimal parameters in n-dimensional space is presented, which encodes movement direction and distance and searches from coarse to precise. The algorithm can realize global optimization and improve the search efficiency, and can be applied effectively in industrial optimization, data mining and pattern recognition. 展开更多
关键词 Genetic algorithm Genetic chain operation Data mining
下载PDF
Design and Implementation of Image Acquisition System Based on STM32
14
作者 QIN Wei YU Chaogang 《International English Education Research》 2017年第2期64-66,共3页
In order to solve the difficulty of reading inconvenience in the measurement process of digital track gauge, a kind of image data acquisition system with low cost and stable performance is designed. The system uses th... In order to solve the difficulty of reading inconvenience in the measurement process of digital track gauge, a kind of image data acquisition system with low cost and stable performance is designed. The system uses the Cortex-M4 as the core of the STM32F407ZGT6 as the control core, the use of OV2640 as an image sensor to collect images, and the collection of image files stored in the SD card for subsequent image processing to achieve the goal of rail adjustment to lay the foundation. The experimental results show that the image acquisition is stable and refiable and the collected images are clear and meet the design requirements. 展开更多
关键词 STM32F407 OV2640 Image acquisition
下载PDF
The Design and Implementation of Multi-user Data Sharing Platform for Remote Monitoring System Based on Virtual Instruments
15
作者 Ma GuoSheng Xia XiaoBo 《International Journal of Technology Management》 2014年第8期79-82,共4页
Remote data monitoring system which adopts virtual instrument usually applies data sharing, acquisition and remote transmission technology via internet. It is able to finish concurrent data acquisition and processing ... Remote data monitoring system which adopts virtual instrument usually applies data sharing, acquisition and remote transmission technology via internet. It is able to finish concurrent data acquisition and processing for multi-user and multi-task and also build a personalized virtual testing environment for more people but with fewer instruments. In this paper, we' 11 elaborate on the design and implementation of information sharing platform through a typical example of how to build multi-user concurrent virtual testing environment based on the virtnal software LabVIEW. 展开更多
关键词 Virtual Testing Environment Data Sharing Platform Concurrent Data Acquisition and Transmission Data Redundancy
下载PDF
Design and Description of a Photovoltaic Pumping System: Application in the Site of Adrar 被引量:1
16
作者 Ahmed Mehdaoui Amar Hadj Arab Djaafar Seminar 《Journal of Environmental Science and Engineering(B)》 2012年第2期183-186,共4页
The Saharan areas and in particular the isolated sites are characterized by low levels of population, in dispersed cores, which suffer from serious problems of water supply for consumption and the irrigation. The phot... The Saharan areas and in particular the isolated sites are characterized by low levels of population, in dispersed cores, which suffer from serious problems of water supply for consumption and the irrigation. The photovoltaic pumping systems (PV) are an ideal solution for these problems. Despite the presence of several photovoltaic pumping systems (PVPS) projects, data acquisition system is still missing in most cases. In this work, the authors will present the PVPS installed at the unit of research in renewable energies in Saharan medium (URERMS, Algeria). This system will enable us to better analyze the performances ofa photovoltaic pumping system in Saharan medium. The principal elements of the chain of the photovoltaic pumping system are: a photovoltaic generator, the power conditioning system, a motor-driven pump immersed group, an electric wiring, a hydraulic infrastructure which comprises a water tank. 展开更多
关键词 Photovoltaic pumping DIMENSIONING optimization system of irrigation performances.
下载PDF
Inverse Estimation on Trigger Factors of Simultaneous Slope Failures with Purification of Training Data Sets
17
作者 Hirohito Kojima Ryo Sekine +1 位作者 Tomoya Yoshida Ryo Nozaki 《Journal of Earth Science and Engineering》 2013年第9期594-602,共9页
This paper presents an procedure for purifying training data sets (i.e., past occurrences of slope failures) for inverse estimation on unobserved trigger factors of "different types of simultaneous slope failures"... This paper presents an procedure for purifying training data sets (i.e., past occurrences of slope failures) for inverse estimation on unobserved trigger factors of "different types of simultaneous slope failures". Due to difficulties in pixel-by-pixel observations of trigger factors, as one of the measures, the authors had proposed an inverse analysis algorithm on trigger factors based on SEM (structural equation modeling). Through a measurement equation, the trigger factor is inversely estimated, and a TFI (trigger factor influence) map can be also produced. As a subsequence subject, a purification procedure of training data set should be constructed to improve the accuracy of TFI map which depends on the representativeness of given training data sets of different types of slope failures. The proposed procedure resamples the matched pixels between original groups of past slope failures (i.e., surface slope failures, deep-seated slope failures, landslides) and classified three groups by K-means clustering for all pixels corresponding to those slope failures. For all cases of three types of slope failures, the improvement of success rates with respect to resampled training data sets was confirmed. As a final outcome, the differences between TFI maps produced by using original and resampled training data sets, respectively, are delineated on a DIF map (difference map) which is useful for analyzing trigger factor influence in terms of "risky- and safe-side assessment" sub-areas with respect to "different types of simultaneous slope failures". 展开更多
关键词 Purification of training data simultaneous slope failures inverse analysis of unobserved trigger factor spatial data integration structural equation modeling.
下载PDF
Manifold alignment using discrete surface Ricci flow
18
作者 Zhongxin Liu Wenmin Wang Qun Jin 《CAAI Transactions on Intelligence Technology》 2016年第3期285-292,共8页
Manifold alignment is useful to extract the shared latent structure among multiple data sets and the similarity among different datasets. As many kinds of real world data can be analyzed using low dimensional represen... Manifold alignment is useful to extract the shared latent structure among multiple data sets and the similarity among different datasets. As many kinds of real world data can be analyzed using low dimensional representations, manifold alignment algorithms can be used in a wide range of applications, such as data mining. In this paper, we propose a three-stage approach to manifold alignment using discrete surface Ricci flow. Our approach transforms the original intrinsic manifolds to hyper spheres using confonnal mapping in the first stage, and then zooms these hyper spheres into the same scale and aligns them in the following stages. We describe in details about our algorithm, its theoretical principles, our experimental results, and the comparison to previous alignment methods. To prove the effectiveness of our algorithm, three kinds of experiments are presented, including a toy dataset, one containing parallel corpus of parliament proceedings and another containing both images and texts. With these experiments, the latent utility in discovering the similarity among different kinds of data sets can be demonstrated, whether within the same kind of data or across different kinds of modals of data. 展开更多
关键词 Cross-lingual retrieval Cross-media retrieval Dimensionality reduction Manifold alignment
下载PDF
Design of DSP-based Embedded Video Remote Monitoring System
19
作者 CHEN Lei WANG Jin-hai DONG-le 《Semiconductor Photonics and Technology》 CAS 2009年第3期173-178,共6页
Presented is a scheme of an embedded video remote monitoring system based on TMS320DM642. Using DM642 as the data processing core, the remote monitoring system is composed of video acquisition module, video processing... Presented is a scheme of an embedded video remote monitoring system based on TMS320DM642. Using DM642 as the data processing core, the remote monitoring system is composed of video acquisition module, video processing module and communication module, which gives an implementation of class/mini driver module in DSP/BIOS integrated developing environment and also a common task module in application layer is achieved. The system realizes the entire functions of the analog video signal acquisition, H.264 video coding and Internet transmission. It provides the general connection for the future development and has good flexibility and extendibility. The system uses a modular design and overall development of programming methods to improve the efficiency of system development. 展开更多
关键词 DM642 remote monitoring system H. 264 video capture network interface
下载PDF
Teletandem as a Way of Enhancing Language Learning Between Brazilian and German Students
20
作者 Suelene Vaz da Silva Francisco Jose Quaresma de Figueiredo Warde da Fonseca-Zang 《Sino-US English Teaching》 2014年第10期767-776,共10页
This paper aims at investigating the teletandem learning interactions between a group of Brazilian students from Instituto Federal de Educagao, Ciencia e Tecnologia do Estado de Goias, Brazil, and a group of foreign s... This paper aims at investigating the teletandem learning interactions between a group of Brazilian students from Instituto Federal de Educagao, Ciencia e Tecnologia do Estado de Goias, Brazil, and a group of foreign students from two German universities. In this study, the Brazilian students helped their foreign partners with Portuguese learning and were helped by them in the English learning. The participants used a synchronous computer software called Openmeetings and also an electronic dictionary as a complementary tool. Adopting a qualitative perspective in the data collection and analysis, this case study was conducted in the second semester of 2010. The data were collected by means of conversation sessions through Openmeetings and were analyzed in the light of studies on sociocultural theory as well as on tandem/teletandem language learning researches. The data analyses showed that the participants used English as an anchoring language to work with Portuguese and English itself, and German was introduced in the teletandem sessions. The data also showed that the whiteboard and the electronic dictionary were used as complementary resources to the use of audio and video for the language learning process the participants engaged in. 展开更多
关键词 language learning Openmeetings teletandem
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部