小流域条件下岩溶落水洞的过流能力评价方法探索

贵州省岩溶分布广泛,小流域地面单元多元化,岩溶落水洞往往是小流域微地貌的过水通道．根据岩溶地区小流域的特殊条件,结合暴雨洪水各种评价方法,从而较好地评价岩溶落水洞的过流能力．     

Analysis of ice slurry production by direct contact heat transfer of air and water solution

In this paper, a novel system using direct contact heat transfer between air and water solution was proposed to generate ice slurry. The heat transfer process and the system performance were studied; energy efficiency coefficients of 0.038, 0.053, and 0.064 were obtained using different solutions. An empirical relationship between the volumetric heat transfer coefficient Uv and the main parameters was obtained by fitting the experimental data. The Uv calculated from the empirical formula agreed with the experimental Uv quite well with a relative error of less than 15%. Based on the empirical formula, a laboratory-scale direct contact ice slurry generator was then constructed, with practical application in mind. If the air flow rate is fixed at 200 m3/h, the ice production rate will be 0.091 kg/min. The experimental results also showed that the cold energy consumption of the air compressor accounted for more than half of the total amount. To improve the system energy efficiency coefficient, it is necessary to increase the air pipes insulation and the solution＇s thermal capacity, and also it is appropriate to utilize the free cold energy of liquefied natural gas （LNG）.     

从符号的角度分析韩非对《老子》的解读

韩非巧妙利用了汉语多义的特性,有意混淆道德与利得、态势与权势、正义与适宜等概念.一方面利用老子的宇宙之道贬低仁学现实主义的人世之道;另一方面,对“道”进行为我所用的阐释,将理作为道的说明依据,以形名之计使得法、术成为遵循宇宙之道的大法,使法、术、势成为法家的三驾马车.     

清代至民国京畿地区的水利纠纷及其解决措施

清代,京畿地区的水利事业得到了全面发展。受自然、社会与历史因素的制约,京畿地区的水利纠纷较为频繁,并有不同的类型与地域特点。进入民国以后,京畿地区的水利纠纷及其解决亦呈现出典型的"近代"特色。为解决水利纠纷,当地采取了包括立碑刻石、完善管理、加强水利设施建设和改变传统用水习俗在内的多种措施。     

钠与水反应的实验装置改进

高中化学教材中钠与水反应实验虽然简单,但无法让学生直观看到反应生成的气体,且未能对该气体性质进行论证即给出结论,不利于学生探究精神的培养;同时,该实验容易因取用钠太大造成实验事故。文章通过改进实验,能清楚观察到气体的生成并对其溶解性、可燃性进行验证,并能观察到钠在煤油和水层反应的跳动现象,效果明显,实验成功率100%,不存在安全问题。     

全球稀土进口竞争格局分析及潜在贸易联系预测

稀土是一个国家经济社会发展极其重要的战略资源,从长时间尺度分析其进口竞争格局并预测未来潜在的贸易联系可为稀土进出口国制定和调整稀土贸易政策提供参考.以稀土(HS:280530)为研究对象,运用复杂网络方法,构建1990-2018年全球稀土进口竞争网络,分析全球稀土进口竞争格局、演变特征,大洲、国家间竞争特点以及对中国稀...     

基于知识势差的图书馆知识传播模式研究

"书是为了要用的",实现知识的有效传播,促进知识创新是图书馆的应有之义。图书馆与用户之间因为知识存量的差异而形成一定强度的知识势差,从而导致图书馆向用户进行知识传播。在对图书馆知识势差内涵分析的基础上,探讨了基于知识势差的知识传播成因,并构建了图书馆知识传播的网络模式、循环模式和需求层次模式。     

Use of Polarised Light Microscopy to Improve Conservation of Parchment

ABSTRACT

The preservation state of parchment primarily depends on the structure of the collagen fibre network, which in turn is responsible for optical anisotropy, i.e. birefringence. Polarised light microscopy can therefore be used as a non-invasive technique that allows recording of birefringence distribution in the parchment, which directly relates to stress–strain distribution. Using samples from diverse sources (commercial parchment, parchment used by restorers for book binding, and parchment fabricated for the purpose of this study), we assessed the capability of polarised light microscopy for various diagnostics. We performed, for instance, identification of gelatinised regions, layered or ?brous regions in parchment cross section, qualitative analysis of parchment fat content (lipids), observation of stress-induced patterns resulting from tensile tests, and observation of water diffusion. These proof-of-principle experiments extend the capability of polarised light microscopy far beyond its common use and open the path to its deployment in conservation studies.     

Impact of Universities' Promotional Materials on College Choice

ABSTRACT

A major promotional tactic for higher education marketers is the use of printed promotional materials to recruit freshmen students. These promotional materials range from full color glossy brochures to simple letters on university letterhead. They are sent to students during their junior and senior years in high school.

The research reported in this article attempted to provide in-depth information on the impact of these promotional materials through the use of student focus groups. Students from a large, southern metropolitan university were asked about the impact of these promotional materials on their college choice decision. The students provided detailed suggestions on the ways to improve the method of distribution, graphic design, and content of the materials.     

工业用水总硬度在线检测方法探索

将流动注射技术应用于水中总硬度的分析,并在各种实验条件下研究相关因素的影响.在EDTA浓度为0.02 mol/L时,检测范围能满足国标要求的5～1000 mg/L测量范围,能够很好地应用于炼钢厂中生产用水、锅炉水的总硬度的在线测定.