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1.
《科技风》2021,(26)
液位控制是日常生活和工业过控系统中常见的控制问题之一,要实现精确的液位控制目标,需要选择合适的液位传感器。本文主要围绕不同液位传感器的测量原理及方式,分析了不同类型液位传感器的研究现状。通过分析各类主流液位传感器研究和使用中出现的普遍性问题,对主流液位传感器技术未来的发展趋势进行了展望。  相似文献   

2.
《科技风》2020,(9)
保持船舶的平稳是船舶运行的首要所在,实际是通过前后、左右的压载舱注水排水补偿船舶重心偏移以实现船舶平衡。为此,需要研究开发压载舱的液位测量和控制。本文设计了一套能够模拟有关液位测量和阀门控制的实验系统,利用液位传感器对模拟的压载舱及船舶四角吃水进行了信号采集,通过PLC实现了与上位机的通信和对阀门的控制,利用组态软件开发了上位机监控界面,通过界面可实时监测液位和设备的运行状态,模拟船舶装卸货的过程,控制阀门和泵,调节液位。  相似文献   

3.
石油作为最主要的能源广泛应用于生产生活的各个环节,全球石油资源被开采进而通过加工循而有序的被用于生产生活的各方面。在整个从开采到最终消耗的各个环节,各种形式的临时存储方式扮演着重要角色,或是原油罐、或是运油车、或是成品油库保证了一定数量的油品准确无误传递。磁致伸缩液位传感器是一种可广泛应用在石油、化工行业的各种液罐的液位计量的传感器。它支持多种信号输出,一台传感器可同时测量液面、界面及多个温度点,与其他液位变送器或液位计只可检测单液面相比,有明显的优势,为客户提供优秀测量方案,节省费用。  相似文献   

4.
液位作为一个主要热工参数,其常用的检测方法有多种,随着科技的进步,人们生活空间的扩大,需要液位检测的地方越来越多,环境越来越复杂,技术要求也越高,为此先进的检测技术和仪器随之出现,如光纤传感器、微波传感器等。这里以光纤液位传感器为例,介绍光纤的结构、原理、液位检测方法及应用。  相似文献   

5.
机车领域的发展为社会经济的进步做出了很大的贡献。同时,也正是在社会经济的发展过程中,各种机型的机车不断推出。DF11G型机车就是其中比较突出的一款。DF11G型机车推动了机车领域的发展,然而,在DF11G型机车运用的过程中,其燃油液方面总会出现一些故障,严重的影响了DF11G型机车的发展和应用。因此,对于DF11G型机车燃油液位移原理及故障处理的研究是十分有必要的。主要阐述了液位传感器的工作原理,分析了液位传感器的故障处理,并对液位传感器的检测进行了一定的探索和研究,旨在为促进DF11G型机车燃油液位仪的故障处理水平而提供一些有价值的参考意见。  相似文献   

6.
本文主要介绍基于磁致伸缩原理的作为测量原理,并且带Hart协议输出的二线制液位传感器,从系统原理、硬件、软件等方面阐述该液位传感器的设计要点。  相似文献   

7.
宋冬萍 《内江科技》2012,(11):106+187
目前,国内使用的加样针液位传感器存在成本高、准确性低的缺点,不能满足精确加样的需求。因此,本文设计了一种基于C8051F330单片机的新型传感器,通过对传感器A/D数据分析,选择合适的判断阈值,能实现传感器对液位的精确判断。经大量实验证明,本文设计的传感器完全满足常规血检项目需求,检测精度高、性能稳定,具有较强的市场竞争力。  相似文献   

8.
设计-种液位实时检测系统可以自动检测液位,此控制系统是基于单片机及其相关硬件来实现的,通过传感器获取实时液位,并将结果送至上位机以控制液位为期望值.当液位低于设定的期望值时,系统自动调节阀开度;当液位到期望值时,系统自动调节阀门关闭.  相似文献   

9.
依据罐测量系统自动液位传感器工作原理,以测量储液罐空高为测量方法,使用科学合理的校准依据,按照相关技术要求,计算和评定出自动液位传感器测量结果的扩展不确定度。  相似文献   

10.
在油田生产中,原油沉降罐中油水界面及液位的准确测量对于油田的正常生产有着重要的作用。目前的油罐液位及油水界面测量装置误差较大,本文提出通过逐点阻抗测量技术这一全新的测量方法来提高液位及油水界面的测量精度,从而精确的计量油罐中油层的厚度,同时也能精确显示液中的含水率,为生产工艺的调整及相关部门的决策提供可靠依据。  相似文献   

11.
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors.  相似文献   

12.
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007.  相似文献   

13.
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction.  相似文献   

14.
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China's science enterprise by making S&T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party's Leading-member Group at CAS, which was held from 7 to 11 January in Beijing.  相似文献   

15.
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants."  相似文献   

16.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies.  相似文献   

17.
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means.  相似文献   

18.
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP.  相似文献   

19.
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.  相似文献   

20.
<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence  相似文献   

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