Some differential inequalities for thermohaline convection in bounded containers of arbitrary shape

We have used the theory of self adjoint operators to derive a number of useful differential inequalities for thermohaline convection in containers. Variation of critical eigenvalues with boundary conditions, domain size and fluid properties is shown. Exchange of stabilities is assumed in general but is shown to be always true for the case of fluids, which are salted above and heated below. The differential inequalities are useful to obtain first order effects of the various parameters on the critical eigenvalues.     

浅谈与测量不确定度有关的几个易混淆的概念

讨论了与测量不确定度有关的几个易混淆的概念,通过举例进一步深化对这几个概念的理解,有助于在实践中更有效地运用测量不确定度。     

钟罩式气体流量标准装置自动控制系统

由于钟罩式气体流量标准装置工作效率低下,已经不满足大量的计量检定工作要求。通过计算机软件建立一个自动控制系统,尽可能地提高钟罩式气体流量标准装置的工作效率。该系统使老旧的装置能够再次得到利用,并且保证原始数据的准确性,便于存档和查询。     

优化会计信息质量的思考

在全面，系统分析影响会计信息质量因素的基础上，探讨了如何提高和优化会计信息质量的途径和措施。     

对制图类课程中某些概念的再研究

继文献[1], [2],对制图课程中另一些概念的确切表述进行了研究,主要有投影法,投影轴和投影连线,用迹线表示平面,空间几何元素及其投影,交线、棱线、截交线、相贯线,立体表面交线的可见性,立体、基本立体、组合体,立体图,主向灭点、主灭点、主点,一点透视,阴和影,视图、基本视图,常用件等。提出了较为确切的表述,指出了一些表述不够确切、严谨的问题。对这些问题的继续深入研究讨论,十分有利于课程和教材的质量和水平的不断提高,为精品课程和教材建设创造了条件和基础。     

做好实验室管理工作的几点认识

笔者从事实验室工作5几年,深知其在生产经营、研发过程中的重要性,如何作好检测工作,提高工作质量、工作效率,也是每个实验室管理者所关心的问题,以下几点认识是我多年来工作经验的积累,愿与大家共同分享、共同探讨,不断提高实验室管理水平.     

资讯

<正>佳能EOS单反相机累计生产突破4000万台佳能公司2010年5月13日正式宣布EOS单反相机累计生产突破4000万台(胶片单反相机与数码单反相机合计),达到相机生产的新的历程碑。     

资讯

索尼W350D这是一款专属于美眉的数码相机——从此你的手袋里不只必备化妆包。也可以有这款索尼最新发布的DSC-W350D。     

news

月度热点SHARC处理器的起源和演进探讨http:/designnews.com.cn/0910-101.aspx说到要求超高性能的前沿应用,就不得不提起ADI公司的SHARC处理器。随着更高动态     

news

design博览汇第一集正式播出石振宇谈健康座椅的设计http://video.designnews.com.cn/blh内容介绍:石振宇谈健康座椅设计,以及相关的设计故事。石振宇老师在设计椅子之前,首先一件事是买来20把全世界最著名的,花了很多钱,十多万都不止。他还调查了全世界300多家生产椅子延续的历史。然后石老师在这300     

news

论坛:全新改版关注设计界热点,与工程师一起讨论不可思议的产品都如何实现? http://bbs.designnews.com.cn/网上研讨会预告康耐视机器视觉为您排忧解难时间:2009-09-16 09:50-12:00网址:webcast.designnews.com.cn专家简介:丁正勇美国康耐视公司中国区技术培训师多年来一直致力于机器视觉行业,具有丰富的实际应用经验,尤其在电子、医药、包装、食品、汽车等行业。     

Some remarks about the flux periodicity in SQUIDS

A topological approach is used to show that the flux periodicity of any practical single-junction rf SQUID or double-junction dc SQUID device is one flux quantum (₀). The flux periodicity is independent of the number of superconducting loops and circuit inductances. The topological point of view explains how multihole configurations can be derived from a toroidal one. Weak links are considered as topological switches that allow magnetic flux lines to pass from one homotopic class of loops to another. In addition to rf SQUIDs in the hysteretic or nonhysteretic regime, we also consider resistive and dc SQUIDs. Some special cases are also introduced where the flux periodicity is not ₀, due to special nonlinear behavior of the weak link, due to coupling to a resonant circuit, or because of a great number of weak links in the superconducting circuit. The flux periodicity of a SQUID is a property of the weak link itself, and not of the inductances connected to it. Only the number of weak links and their mutual connection in series or parallel can change the fundamental flux periodicity of the device.     

Some remarks about time in Newtonian particle mechanics

Summary In the Principia, Newton stateda priori (in the first pages of Volume I) that the flow of time is uni-directional and uniform. In this paper, the Newtonian universe including time and its arrow is defined with some precision, and the needed axioms are listed which yield Newton's flow of time a consequence, rather than ana priori assumption, of classical particle mechanics.     

设计流量积算仪时需注意的几个问题

流量积算（或显示）仪是一种多参量综合计算的仪表,最终结果的准确度是各环节的综合误差,本文就多次浮点运算、温度、压力测量回路、采样周期的选取等方面分析产生误差的原因,以便在设计时引起注意。     

浅谈测量精度计算及应用

每一次测量,都存在误差。本文给出了系统误差和随机误差传递的一般公式,以及特殊情况下的变形公式,并合理介绍了其应用技巧,同时也说明了系统误差和随机误差的转化情况。