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1.
This thesis studies circuit model for calculating transient overvoltages on the signal cable conduuctors,and the computational method and program of cable parameters.The transient overvoltages on the signal cable conductors ocurring equipment faulting in a 500 kV power system is calculated by EMTP.  相似文献   

2.
The importance of human-information system interaction efficiency within enterprise informationization environment is analyzed.The intension of human-information system interaction efficiency is studied from definition,characteristic and evaluation.According to different properties,the influencing factors of human-information system interaction efficiency are divided into five kinds,including human factor,information system factor,management factor,environment factor,and technology factor.On this basis,the concept model of human-information system interaction efficiency is brought forward,and mechanisms of influencing factors to human-information system interaction efficiency are discussed in the model.The analysis indicates: As the core parts of the model,human factor and information system factor determine interaction efficiency directly.Management factor restricts or supports efficiency of human and information system.Environment factor and technology factor bring indirect influence to interaction efficiency by restricting or supporting human factor and information system factor.  相似文献   

3.
Water level has risen considerably since the impounding of the Three-Gorges Reservoir in year 2003 and that might cause serious geologic hazards, including landslides. Primarily using GPS technique, the landslides wireless monitoring in the Three-Gorges Reservoir is developed in rapidnly. To collect data and monitor in engineering more rational, the system model of GPS technique and its application in landslides monitoring are analyzed. Focusing on the data collection in monitoring, the authors discuss the method of embedding control in the monitoring model. By connecting the character of the monitoring system and landslides, the control signal is produced. At last, the experiment is performed with analogy software in monitoring system including control. The experiment indicates that the control signal is reasonable and valid. In actual engineering, this method is made progress.  相似文献   

4.
苏州 《粮食储藏》2012,41(4):3-7
设计了一个基于ARM技术的粮库嵌入式监测系统.该监测设备由两部分结构组成:一个是上位机电脑控制端对粮食信息的监测和处理,另一个是在下位机实现对粮仓粮食数据的采集,信号的处理以及通讯的功能.通过工业以太网或GPRS网络可以将数据从一方传给另一方.在此基础上展开以S3C2410处理器来实现粮食相关信息监测的研究,其中人机交互界面终端通过Qt/E来设计.试验测试结果证明了该系统的可靠性和稳定性.  相似文献   

5.
The robust control theory is used to solve the uncertainty of the optical extra-precise vibration isolation system. The wavelet theory is used to analyze the random vibration signal in the time-frequency domain and get the low frequency signal from the random vibration signal. The robust controller designed by the robust control theory is used to restrain the low frequency vibration. The active vibration isolation exploits the theory of robust control, which overcomes the uncertainty of model and the disturbance, and makes the control system to restrain the uncertainty of the model and the disturbance of the vibration. The simulation results prove that this method has shown good robustness and control precision in the vibration isolation of the optical extra-precise instrument and have good performance on restraining the low frequency vibration.  相似文献   

6.
研究农地产权制度多样性的理论和历史,正确认识农地产权制度改革中的新情况和新问题具有重要意义。模型和历史分析表明,农地产权制度的多样性是农民生产组织自觉追求制度利润的结果。农地产权制度的多样性有利于农地产权的制度竞争,有利于农村生产力水平的提高。农地产权制度的政策选择要与当地的农村经济发展水平相适应。政府在产权制度改革进程中不但要发挥其增加制度收益的积极作用,如促进农村集体经济组织建设,建立城乡人力资源互动机制,适当提高农产品收购价格等,而且要约束其增加制度成本的行为。  相似文献   

7.
In view of the relationship between executive ability and landscape design teaching, the paper put forward that the executive ability is a key factor restricting teaching effects of landscape design, and then analyzed factors influencing executive ability of subject-object (teachers and students) in the teaching. Aiming at these factors, executive ability of teachers and students in landscape design teaching could be improved by modifying teaching management system, teacher training, developing the role of "project-oriented learning" in shaping the executive ability, and cultivating students' self-study ability, so as to improve the teaching effect of landscape design.  相似文献   

8.
侧根构型直接影响植物根系形态建成,是植物整个根系的重要组成部分,在植物抗逆反应中起着重要作用。为了研究植物激素脱落酸(ABA)调控侧根生长发育的分子机制,本研究归纳了ABA在侧根发育中的信号传递,揭示了ABA在侧根起始中的双重作用和ABA对侧根分生组织活性的抑制作用。并分析了在侧根发育过程中ABA与其他调控因素包括活性氧(ROS)、生长素、细胞分裂素、碳和氮信号,以及盐胁迫间的交叉对话机制,指出ABA通过诱导根中ROS的产生,拮抗生长素和协同细胞分裂素的作用从而达到抑制侧根生长发育;ABA还参与了复杂的碳和氮信号调控的侧根发育过程;此外,ABA信号介导了盐胁迫对侧根发育起始的抑制。ABA调控侧根生长发育的分子机制的揭示可以为改善植物根系性状,提高作物抗逆性提供指导作用,然而,ABA对根生长调控的分子机制还不是很清楚,根系形成也十分复杂,因此需要更多的努力。  相似文献   

9.
A method of detecting the signal frequency which is disturbed by the noise based on the autonomous chaotic system is proposed. A signal with noise was added to an autonomous chaotic system, and then a negative feedback was imposed to it. The feedback gain was appropriately adjusted, so as to let the noisy system orbit be a limit cycle. The number of times that the orbit went directly through a plane was calculated by loop phase technology, and the vibration frequency was found according to it. The frequency of system is determined by the frequency of the test signal, yet free from noise, so the frequency of the test signal is the vibration frequency of the system. Simulation results further demonstrate the effectiveness of the method.  相似文献   

10.
Application system generally refers to all kinds of computer information system. It aims at improving the sharing and application of the resource. The resource in application system usually means data resource. For computer management and maintenance, there are not only data resource, but also program resource and network resource. Effective management of this resource is key to ensure proper work of the application system. In this paper, the basic pattern and policy for resource management is put forward and a method to build and realize the resource layer that lies between database layer and application layer is to be found. This management layer, which skillfully connects the application system with resource and establishes good base for application and exploitation of system, is named as resource management system.  相似文献   

11.
高盐是限制农作物生长和生产最主要的非生物逆境之一。土壤中过多的盐离子对植物细胞造成渗透、离子和氧化胁迫。植物感知胁迫信号后,激活脱落酸、盐过敏感通路维持体内渗透平衡和离子稳态,运行抗氧化系统以应对过量的活性氧。本文通过信号转导、渗透保护剂及溶质的生物合成、离子稳态及区域化、抗氧化系统和植物激素调控等方面综述了植物盐胁迫反应的组成、途径及其调控机制的研究进展,有助于研究人员在逆境条件下培育高产优质的农作物。  相似文献   

12.
This paper studies a long-term program of education development in the light of the theory and method of system engineering.A complete mathematical-Simulant model system is used to describe the internal regularity of an edu-cation system inside a social-economic tystem,and to put forward a set of efficient method for education development programming.The mathematical-simulant model system dis-cussed in the paper is put to practical use in a regional education programming.  相似文献   

13.
舞毒蛾是一种食性广、危害大的林业害虫,遗传多样性的研究有利于揭示不同地理种群的遗传变异情况。以河北舞毒蛾为实验材料,对ISSR反应体系中的5个因子(Taq DNA聚合酶、模板DNA、引物、MgCl2和dNTPs)的8个浓度梯度依次进行试验,每一因子的最佳浓度都用于下一组优化试验,最终确定最佳反应体系优化筛选,结果表明,20μL ISSR反应体系各组分的最适浓度分别为0.5 U Taq DNA聚合酶,1.5 ng/μL模板DNA,2.4μmol/L引物,1.75 mmol/L MgCl2,0.28 mmol/L dNTPs。这一优化的舞毒蛾ISSR-PCR反应体系为进一步利用ISSR分子标记技术对舞毒蛾的遗传多样性分析奠定了良好的试验基础。  相似文献   

14.
During the last four decades, reinforced-concrete structure failures have been happening widely for many reasons, such as increased service loads, war accidents, fire, and durability problems. The economic losses due to those failures are very high. An expert system is an interactive computer-based decision tool that uses both facts and heuristics to solve difficult problems based on knowledge acquired from experts. To realize these requirements, a logic programming visual basic language is used together with visual diagnosis. The expert system, Diagnosis of Fire-Caused Damages to Reinforced-Concrete Tunnel Lining (DFCDRCTL) was developed in this work for diagnosing the annual damages caused by fire. The program is used as an alternative of a human expert to make annual technical decisions in diagnosing fire damages at the second reinforced-concrete tunnel lining segment. It is concluded that the proposed DFCDRCTL expert system is easy to use, and is fast and helpful for engineers.  相似文献   

15.
土壤的盐化和碱化往往伴随发生,在盐碱胁迫下,植物会遭受许多类型的非生物胁迫,严重影响植物的正常生长发育。本综述首先介绍了盐碱土的分类;其次从四个方面对植物在盐碱胁迫下体内产生相应生理机制进行详细介绍;接下来以植物在盐碱胁迫下产生的钙信号为重点进行阐述,包括植物首个非离子通道型盐胁迫下离子感受器GIPCs的发现、盐碱胁迫诱导的钙信号相关通道和转运蛋白、钙信号的感受与传递、以及其他与钙离子信号产生交叉的信号通路的研究进展。在碱胁迫中与钙信号的相关研究鲜有报道,本综述也介绍了此方面的最新研究。最后,对该研究领域目前需要解决的科学问题进行展望。  相似文献   

16.
平原区土地生态安全评价——以延津县为例   总被引:3,自引:3,他引:0  
健康的土地生态系统是人类健康和经济发展的决定性因素。随着人类对土地的利用强度和范围日益增大,在尊重生态规律的基础上,对区域土地生态安全性进行评价显得尤为重要。本研究以平原区的延津县为例,基于P-S-R概念框架模型,建立了包含17项指标的区域土地资源生态安全评价指标体系。运用层次分析原理和土地生态安全模型对该区2006-2008年的土地生态综合安全值进行计算。研究表明,制约平原区土地生态安全的主要因素有:环保支出占GDP的比重、农药使用量、耕地面积比重和人口密度等;2006-2008年延津县区域土地生态状况处于敏感级,且逐年好转。最后,提出改善平原区土地生态安全的建议。  相似文献   

17.
食品专业课程体系建设初探   总被引:4,自引:1,他引:3  
通过分析食品专业课程体系的现状和存在的问题,提出食品专业课程体系建设中理论教学、实验教学和实践教学的改革方案。引进学生自主因素,使食品专业的课程体系更加人性化、合理化。充分调动学生学习的积极性、主动性,培养学生的动手能力和创新能力,为国家经济建设培养出高素质的食品专业人才。  相似文献   

18.
The essentiality of human information system interaction efficiency was analyzed under the computerization environment of enterprises. Information processing ability was measured from three dimensions: working memory, cognitive skill, and computer self efficacy. The experimental method was used to study the influence of information processing ability on human information system interaction efficiency. Multiple regression results show that cognitive skill is the main factor influencing interaction efficiency for skill based tasks, working memory is the main factor for rule based tasks, and working memory has no significant influence on interaction efficiency for knowledge based tasks. Working memory and computer self efficacy are the main factors influencing interaction efficiency for total tasks.  相似文献   

19.
This paper introduces the software and hardware designs of minitype gas dynamotor system based on ATMEGA8L singlechip. Step motor is used as the executing equipment in the system. The maximum power of the dynamotor is 5 kW. First, the speed of the dynamotor is sampled, and then the signal is send to the ATMEGA8L singlechip, so as to drive the step motor, thus to control the accelerograph, and to control the frequency of the 9atput voltage, and the main arithmetic is the PID algorithm. The result shows that this technology can be used and extended in producion.  相似文献   

20.
Summary Unconscious selection may be defined as non-intentional human selection. The term was introduced by Darwin and its modern concept was developed by C.D. Darlington. Unconscious selection, or automatic selection as it is sometimes called, could have been responsible for most of the differences that distinguish domesticated seed crops from their wild progenitors, including loss of natural dispersal mechanisms, even and rapid seed germination, larger propagules, simultaneous ripening, and loss of mechanical protection as well as changes in the breeding system. Some differences, such as those in seed or fruit colors, may have developed from conscious selection at an early time. For unconscious selection to operate in the development of domesticated plants there would have to have been a deliberate planting of seeds by people.  相似文献   

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