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随着控制、计算机、通讯、网络技术的发展,计算机网络集成自动化系统在现代工业企业中已得到广泛应用。而作为当今自动化领域技术发展热点之一的现场总线技术的出现,则标志着工业控制领域又一个新时代的开始。它被誉为自动化领域的计算机局域网,随着现场总线技术的不断完善和推广,这一技术在许多大、中型水泥厂得到了广泛的应用。 相似文献
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CAN总线技术在自动化控制方面称为计算机的局域网。CAN总线使整个自动化系统效率更高,响应更快,控制更加便利。CAN总线技术在工控制领域有强大的优势,越来越多的企业在应用开发新产品。 相似文献
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现场总线是八十年代末在国际上发展起来的用于过程自动化等领域的现场智能设备互连通信网络。在众多的现场总线技术中,由现场总线基金会组织（Fieldbus Foundation,即FF）开发的基金会现场总线（以下简称“FF现场总线”）在过程自动化领域中得到了广泛的应用。FF现场总线是一项较新的技术,尤其是在我国海洋石油工程领域的应用,还相对较少,2002年中国海洋石油总公司才首次提出将嗣L场总线技术应用于旅大油田开发项目。因此本文从理论联系实际应用的角度进行介绍,以便海洋石油工程相关人员了解这项技术。 相似文献
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现场总线（Fieldbus）是当前自动化领域的热门话题,被誉为自动化领域的计算机局域网。信息技术的飞速发展,引起了自动化系统结构的变革,随着工业电网的日益复杂,人们对电网的安全要求也越来越高,现场总线控制技术作为一门新兴的控制技术必将取代过去的控制方式而应用在电力自动化中。 相似文献
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嵌入式系统应用和网络化是目前船舶自动化的发展趋势,利用现场总线技术完成各监控节点的信息通信,可极大提高系统的实时性与可靠性。采用CAN总线技术给出船舶监控系统的通信协议框架设计,并对协议报文格式进行了具体实现。 相似文献
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简要介绍了PROFIBUS现场总线技术的特点,介绍了SIEMENS PLC和PROFIBUS现场总线技术在玖龙纸业天津工厂除盐水处理系统和清水处理系统自动化领域中的应用。 相似文献
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PROFIBUS现场总线作为一种常见的现场总线技术已广泛应用于自动化领域。由于自动化现场的应用环境复杂,PROFIBUS总线结合DCS应用时．PRCFIBus网络在使用中经常出现通讯不稳定的现象,影响DCS整体运行情况。结合PROFIBUS现场总线的理论知识和DCS采集总线数据的方法,本文针对PROFIBus现场总线与DCS无缝融合项目的常见故障给出一套诊断和排除方法。同时也有助于预防并减少工程中的故障发生。 相似文献
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以上海、浙江、北京、江西等地几百家公司高层管理人士为调查对象进行实证研究。结果表明:(1)干中学学习对核心竞争力的形成有正向影响,但不显著;(2)从经验中学习对核心竞争力的形成有正向影响,但不显著;(3)反思学习对核心竞争力的形成有正向影响,但不显著;(4)忘却学习对核心竞争力的形成有正向影响,但不显著;(5)学中干学习对核心竞争力的形成有显著的正向影响;(6)知识冲突学习对核心竞争力的形成有一定程度的负向影响;(7)交互式学习对核心竞争力的形成有正向影响,但不显著;(8)试错学习对核心竞争力的形成有显著的正向影响。 相似文献
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科学、技术、创新政策的涵义界定与比较研究 总被引：5，自引：1，他引：5
目前我国学术界对科学、技术、创新政策的研究主要是从四方面展开的:一是科技政策和创新政策的一般理论研究,二是各项具体政策的实证研究,三是各国政策的比较研究[1],四是政策的评估研究。然而对于科学、技术、创新政策的内涵、区别和实证研究却较少。在系统地阐述了三种政策内涵的基础上,综合国内外学者的观点,剖析科学、技术、创新政策的区别和内在机制,为科学、技术、创新政策制定者提供科学依据。 相似文献
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《Information processing & management》2016,52(1):46-60
In order to successfully apply opinion mining (OM) to the large amounts of user-generated content produced every day, we need robust models that can handle the noisy input well yet can easily be adapted to a new domain or language. We here focus on opinion mining for YouTube by (i) modeling classifiers that predict the type of a comment and its polarity, while distinguishing whether the polarity is directed towards the product or video; (ii) proposing a robust shallow syntactic structure (STRUCT) that adapts well when tested across domains; and (iii) evaluating the effectiveness on the proposed structure on two languages, English and Italian. We rely on tree kernels to automatically extract and learn features with better generalization power than traditionally used bag-of-word models. Our extensive empirical evaluation shows that (i) STRUCT outperforms the bag-of-words model both within the same domain (up to 2.6% and 3% of absolute improvement for Italian and English, respectively); (ii) it is particularly useful when tested across domains (up to more than 4% absolute improvement for both languages), especially when little training data is available (up to 10% absolute improvement) and (iii) the proposed structure is also effective in a lower-resource language scenario, where only less accurate linguistic processing tools are available. 相似文献
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《Information processing & management》2022,59(4):102987
The ability to predict product sales is invaluable for improving many of the routine decisions essential for the running of an enterprise. One significant challenge of sales prediction is that it is hard to dynamically capture changing dependent patterns along the sales time line, because sales are often influenced by complicated and changeable market environment. To address this issue, we model sales prediction as a task of multivariate time series (MTS) prediction, and propose a Spatiotemporal Dynamic Pattern Acquisition Mechanism (SDPA), which comprises four components, described below: (1) In the processing of input data: A Spatiotemporal Dynamic Kernel (SDK) component is designed for MTS to effectively capture different dependent correlation patterns during different time periods. (2) In terms of model design: A Simultaneous Regression (SR) component is proposed to dynamically detect stable correlations by using co-integration based dynamic programming over different time periods. (3) A novel Hierarchical Attention (HA) component is designed to incorporate SDK to detect spatiotemporal attention patterns from the captured dynamic correlations. (4) In the design of loss function, A Change Sensitive and Alignment component (DC) is proposed to provide more future information based on future trend correlations for better model training. The four components are incorporated into a unified framework by considering Homovariance Uncertainty (HU). This is referred to as SDPANet and contributes to model training and sales prediction. Extensive experiments were conducted on two real-world datasets: Galanz and Cainiao, and experimental results show that the proposed method achieves statistically significant improvements compared to the most state-of-the-art baselines, with average 41.5% reduction on RMAE, average 39.5% reduction on RRSE and average 46% improvement on CORR. Experiments are also conducted on two new datasets, which are Traffic and Exchange-Rate from other fields, to further verify the effectiveness of the proposed model. Case studies show that the model is capable of capturing dynamic changing patterns and of predicting future sales trends with greater accuracy. 相似文献
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本文研究产业集群经济状况、集群人才政策、集群文化、集群生活环境、集群内企业人力资源管理对集群内人才成长的影响,并以武汉光谷、北京中关村、苏州工业园区、东莞振安工业园四个产业集群为对象进行实证研究。本文的理论贡献在于证实了：（1）集群经济状况对集群内人才成长有直接的正向的显著影响;（2）集群人才政策对集群内人才成长有直接的正向的显著影响;（3）集群文化对集群内人才成长没有显著的影响,但通过企业人力资源管理间接影响到集群内人才成长;（4）集群生活环境对集群内人才成长有直接的正向的显著影响;（5）集群内企业人力资源管理对集群内人才成长有直接的正向的显著影响;（6）集群文化、集群人才政策对集群内企业人力资源管理有直接的正向的显著影响。本文的研究结果对于正确认识产业集群人才成长优势以及人才集聚的内在机理具有重要的理论价值,也为政府的人才引进和人才开发提供借鉴。 相似文献
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贺小刚 《科学．经济．社会》2007,25(4):42-47
本文以我国的国有企业与民营企业为研究对象,通过大规模的问卷调查进行统计检验,结果表明:相对于民营企业,国有企业在企业家人力资本投资方面存在一定的不足;国有企业家的综合经营能力普遍地高于民营企业家,但国有企业家的努力程度并不如民营企业;无论是国有企业还是民营企业,改进企业绩效的主要因素在于企业家的实际经营能力,而不是努力与激励;国有企业家通过管理者收购等股权改革而持有公司股份,一方面促进了生产效率的提高,但同时又阻碍了企业最终净利润的积累。 相似文献
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全球经济金融危机后,公司面临的不确定性因素日益增多。公司不确定性对企业投资的影响及其经济后果,成为理论和实务界关注的焦点。本文以A股上市公司为样本,研究公司不确定性、非效率投资与资产定价的关系。研究发现:(1)公司不确定性显著加剧公司非效率投资(尤其是过度投资),这在投资者情绪高涨期最明显;(2)公司非效率投资对企业价值的负向影响源于公司过度投资,这在市场投资者情绪低落期最明显;(3)公司投资不足显著正向影响企业价值,这在投资者情绪低落期更明显。本研究丰富了公司非效率投资、资产定价和行为公司金融研究,对企业高管、投资者以及监管者均有启示意义。 相似文献
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妥善处理退稿是关系到学术期刊提升竞争力、创建良好学术品牌的关键环节。本文以国内某研究型大学的286名有过拒稿经历的年轻学者为对象,采用问卷法,探究在拒稿情况下投稿者的审稿公平对于投稿意愿的影响。研究结果发现:(1)在程序、信息、人际三种审稿公平类型中,信息公平对于投稿意愿有显著的积极影响,并为整体公平感完全中介;(2)版面费对于信息公平与投稿意愿的关系存在正向调节作用,而期刊等级的调节效应不显著;(3)整体公平感是区别于具体公平(程序、人际和信息)的构念,对于投稿意愿有额外的解释效力。 相似文献
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Research in natural language processing has increasingly focused on normalizing Twitter messages. Currently, while different well-defined approaches have been proposed for the English language, the problem remains far from being solved for other languages, such as Malay. Thus, in this paper, we propose an approach to normalize the Malay Twitter messages based on corpus-driven analysis. An architecture for Malay Tweet normalization is presented, which comprises seven main modules: (1) enhanced tokenization, (2) In-Vocabulary (IV) detection, (3) specialized dictionary query, (4) repeated letter elimination, (5) abbreviation adjusting, (6) English word translation, and (7) de-tokenization. A parallel Tweet dataset, consisting of 9000 Malay Tweets, is used in the development and testing stages. To measure the performance of the system, an evaluation is carried out. The result is promising whereby we score 0.83 in BLEU against the baseline BLEU, which scores 0.46. To compare the accuracy of the architecture with other statistical approaches, an SMT-like normalization system is implemented, trained, and evaluated with an identical parallel dataset. The experimental results demonstrate that we achieve higher accuracy by the normalization system, which is designed based on the features of Malay Tweets, compared to the SMT-like system. 相似文献