oalib

OALib Journal期刊

ISSN: 2333-9721

费用：99美元

投稿

时间不限

( 2025 )

( 2024 )

( 2023 )

( 2022 )

自定义范围…

匹配条件： “ 汪凯闰” ，找到相关结果约46146条。
列表显示的所有文章，均可免费获取
第1页/共46146条
每页显示 条
食品与药品中维生素C含量的检测方法进展
Research Progress in Development of the Determination Methods of Vitamine C in Food and Pharmaceuticals  [PDF]
朱宏亮, 戴火锋, 汪凯闰, 姚屠鹏, 张蕴, 沈昊宇
Advances in Analytical Chemistry (AAC) , 2013, DOI: 10.12677/AAC.2013.32003
Abstract: 维生素C是人体不可缺少的营养物质之一，人体主要通过新鲜水果、蔬菜或药片来获取或补充维生素C。因此维生素C的含量成为评价食品营养价值和药品质量的重要标准之一。随着对食品安全的日益关心，食品营养中维生素C和医药品的定量分析已经吸引了越来越多的关注。近年来食品与药品中维生素C的检测方法发展较为迅速，主要有滴定分析法、光度法、电化学法、化学发光法、流动注射法、液相色谱法以及原子吸收间接法等。本文对比总结了这些方法的原理、特点以及应用范围，讨论了方法的优缺点，以期为选择合适的检测方法提供一定的参考。

Vitamin C is necessary to the growth and metabolism for human beings. Vitamin C is mainly from fruits, vegetables and medicine, so it is one of the important standards to evaluate the quality of the food nutrition and medicine. With the growing concern of food safety, the quantitative analysis of vitamin C in food nutrition and pharmaceuticals has attracted more and more attention. In recent years, determination techniques of vitamin C in food and pharma- ceuticals have been developed rapidly, including titrimetric method, spectrophotometric method, electrochemical me- thod, chemiluminescence method, flow injection analysis, liquid chromatography and indirect atomic adsorption me- thods, etc. In this work, some principles, characteristic and the recent progress of reported methods have been summarized and compared.

 

资源富集地区经济贫困的成因与对策研究——以山西省为例
王闰平,陈凯
资源科学 , 2006,
Abstract: 煤炭大省山西拥有得天独厚的丰富的自然资源，但是山西经济始终处于一种与其资源禀赋极不相称的落后状态。本文结合国外学者已经取得的研究成果，对煤炭大省山西经济陷入困境的原因进行了深入分析。研究认为在运输系统高度发达、运输成本日益降低的当今世界，资源丰富型国家或地区的资源优势已经逐渐丧失。而许多资源丰富型国家或地区仍然偏重于发展资源生产性行业，往往形成资源产业“一枝独秀”的畸形产业结构，导致制造业衰落，经济价值外逸，人才外流，生态环境恶化，造成巨大经济损失。加之腐败和寻租行为的严重打击，政府又缺乏制度创新的动力，因此最终导致其经济地位的日益下降，这也正是导致煤炭大省山西经济陷入困境的根本原因。最后，本文对山西经济如何走出困境进行了探讨：①积极推动制度创新，通过证券化把自然资源变“活”;②合理调整产业结构，激励制造业及服务业的发展。
Existence of Periodic Solutions for a Type of High Order Neutral Functional Differential Equations
一类高阶中立型泛函微分方程周期解的存在性
汪凯
数学物理学报(A辑) , 2009,
Abstract: By employing the coincidence degree theory, the author studies a kind of higher order neutral functinal differential equation with distributed delay. Some simple conditions which guarantee the existence of periodic solutions to the equation are obtained.
基于数值模拟的气膜孔冷却效率经验公式的修正
An Improved Empirical Formula for Film Hole Cooling Efficiency Based on Numerical Simulation  [PDF]
汪日丰, 包航凯, 贺缨
International Journal of Mechanics Research (IJM) , 2020, DOI: 10.12677/IJM.2020.92005
Abstract: 气膜冷却在燃气轮机叶片冷却中具有明显优势和较强应用前景。已有的经验公式通常忽略气膜孔长径比(气膜孔长度/气膜孔直径)的大小对冷却效率的影响，但长径比与气膜倾角相关，会很大程度影响射流的流动形式，从而对冷却效率的分布影响较大。本文旨在通过数值实验构建一个能够较为准确地预测展向平均气膜冷却效率的经验公式，为初期叶片冷却结构的快速设计提供依据。本文首先通过数值模拟的方法分析了孔间距、气膜倾角和吹风比的大小对展向平均气膜冷却效率的影响，将上述参数总结归纳到所构建的经验公式中，使用Matlab对数据进行非线性拟合，最后与已有经验公式进行对比。结果表明，本文构建的经验公式在拟合效果方面要好于已有的经验公式且决定系数均大于0.9，具有较好的拟合优度。
Film cooling is a prospective cooling technique for maintaining and improving turbine working life with obvious advantages. The existing empirical formulas usually ignores the effect of the ratio of film hole length to the diameter L/D on the cooling effectiveness, but L/D is related to the surface inclination angle of film hole and the size of surface inclination angle of film hole greatly affects the flow pattern of the jet, and thus has a relatively large impact on the distribution of the cooling efficiency. The aim of this article is to construct an empirical formula through numerical experiments which can accurately predict the laterally averaged film cooling efficiency in the early stage of designing blade cooling structure. Therefore, the effects of film hole spacing, surface in-clination angle and blow ratio on the laterally averaged film cooling effectiveness were first inves-tigated by numerical simulations. The nonlinear fitting of the data was performed by using Matlab and were subsequently summarized as an empirical formula which is related to the above param-eters. Compared with the existing empirical formulas, the improved empirical formula can give a better prediction for cooling efficiency, whose coefficient of determination is greater than 0.9.
三维燃料组件流阻数值计算研究
Study on Numerical Calculation of Flow Resistance of Three-Dimensional Fuel Assembly  [PDF]
汪俊, 符凯, 马佳珍
Applied Physics (APP) , 2022, DOI: 10.12677/APP.2022.121003
Abstract: 燃料组件的阻力特性影响堆芯不同类型组件的流量分配，对堆芯设计的影响不可忽视。为得到更为精确的燃料组件流阻特性并获得对应阻力系数，本文采用分段计算方法针对两种工质条件下的燃料组件进行了单通道三维数值模拟研究。结果表明：不同工质下，随着进口速度上升，各计算域局部压降及总压降均增大；不同工质下，对于三种形式的底板阻力系数D，四孔底板最小，圆孔底板最大，Phi孔底板介于前两者之间。最后还获得了工质分别为水和空气时燃料组件区和不同形式底板区的阻力系数，为稳态多孔介质模型中计算表征多孔介质影响的源项S提供了参考，对燃料组件通道的三维数值模拟提供了指导意义。
The flow resistance characteristics of fuel assemblies affect the flow flux distribution of the different types of assemblies in the core, and its influence on the core design cannot be ignored. In order to obtain more accurate flow resistance characteristics and corresponding resistance coefficient of fuel assemblies, a single channel three-dimensional numerical simulation of fuel assemblies under two working fluids is carried out by using the domain division technique. The results show that with the increase of flow velocity of the inlet, the local pressure drop and total pressure drop in each calculation domain increase. Under different working fluids, for the three types of bottom plate resistance coefficient D, four holes bottom plate is the smallest, round hole bottom plate is the largest, and Phi hole bottom plate is between the first two. Meanwhile, the resistance coefficients of the fuel assembly area and different types of bottom plate areas are obtained when the working fluids are water and air respectively, which provides a reference for calculating the source term S representing the influence of porous media in the steady-state porous media model and provides a guiding significance for the three-dimensional numerical simulation of fuel assembly channels.
Causes of Poverty and Anti-Poverty Strategies in Resource Rich Area A Case Study in Shanxi Province
资源富集地区经济贫困的成因与对策研究--以山西省为例
WANG Run-ping,CHEN Kai,
王闰平,陈凯
资源科学 , 2006,
Abstract: This paper explored the reasons why Shanxi run into economical predicament,though it holds a great deal of coal resource.The conclusion is that resource advantage in those nations who hold a great deal of natural resource has been lost because transportation cost has been cut down after science and technology take progress.Those nations who hold a great deal of natural resource always are with abnormal industry structure,whose resource industry proportion is always too bigger than others.That can lead into some harmful results.The first one is that their manufacture sectors will comedown because labors and capital tend flowing into export business.The second one is that a great deal of economical value in these nations will vanish because their exports are ordinarily raw materials,but prices of them are usually much lower than finished products imported from developed countries.The third one is that professionals will flow out of these nations.As far as Shanxi province is concerned,coalmining require very simple technology,and most of mineworkers live depending mainly on their physical power.The fourth one is that environment will become worse than before.Mining is tearing up many scenic areas and making a mess of many rivers and wetlands.Coal-fueled power plants are polluting the air.The fifth one is that natural resources in most of nations are state-owned,and this will undoubtedly lead to serious corruption and over-mining.Therefore,for those nations with plenty of natural resource,their economic degree decline is inevitable.Some revolving ways have been discussed.The first,bring forth new ideas and convert natural resource from "dead " to "living" by the way of stock or bond.In order to accomplish this proposal,an institution system that can make stock market running efficiently is very important.The second,adjust industry structure reasonably,stimulate manufacture industry and service industry.In Shanxi province,the government should cut down coal industry proportion in economic gross and improve manufacture industry proportion,and push tourism forward rapidly so as to get rid of abnormal industry structure and drive economic development.
山西省可持续发展状况生态足迹分析
王闰平,崔克勇,陈 凯,赵月红
中国生态农业学报 , 2006,
Abstract: 应用生态足迹模型分析山西省生态经济系统可持续发展状况结果表明，当前山西省生态经济系统处于一种不可持续发展状态，经济发展是以对自然资源的过度掠夺为代价的；化石燃料生态足迹比重很大（79%），是山西省生态赤字最基本部分，资源利用效率相当低下。山西省亟需改变传统的高消耗发展模式，建立资源节约型社会生产和消费体系。
一种基于预估算法的专家式控制
汪庭凯
重庆大学学报 , 1992,
Abstract: 本文将专家系统技术同预估控制方法相结合,得到了一种新的专家式控制方法。该方法采用多模态控制结构,并结合了在线的特征量识别技术,因而在过渡过程中能够较好地发挥人的控制经验和预估控制算法的作用。仿真实验表明,该专家式控制在被控对象变化或出现故障以及负载突变时均具有很强的鲁棒性和较强的适应能力。
凤尾菇菌丝生长过程的预测模型
汪庭凯
重庆大学学报 , 1987,
Abstract: 作者对凤尾菇菌丝生长过程进行了大量的实验研究,根据凤尾菇菌丝在袋栽情况下的特点,建立了凤尾菇菌丝生长过程的预测模型。仿真实验表明,该预测模型能较好地与实测数据吻合。
具有不精确推理能力的信息管理系统
汪庭凯
重庆大学学报 , 1989,
Abstract: 本文将人工智能中的一些基本思想和方法引入信息管理系统,提出了一种能够根据带可信度的知识进行不精确推理的信息管理系统的设计方案。由该方案设计出的系统不仅具有一定的不精确推理能力,同时还具有适应面广、易变更和扩展等特点。本文介绍了这一设计方案及程序实现技巧。
第1页/共46146条
每页显示 条


Home
Copyright © 2008-2020 Open Access Library. All rights reserved.