Combining reinforcement learning with mathematical programming:An approach for optimal design of heat exchanger networks

Heat integration is important for energy-saving in the process industry.It is linked to the persistently challenging task of optimal design of heat exchanger networks(HEN).Due to the inherent highly nonconvex nonlinear and combinatorial nature of the HEN problem,it is not easy to find solutions of high quality for large-scale problems.The reinforcement learning(RL)method,which learns strategies through ongoing exploration and exploitation,reveals advantages in such area.However,due to the complexity of the HEN design problem,the RL method for HEN should be dedicated and designed.A hybrid strategy combining RL with mathematical programming is proposed to take better advantage of both methods.An insightful state representation of the HEN structure as well as a customized reward function is introduced.A Q-learning algorithm is applied to update the HEN structure using theε-greedy strategy.Better results are obtained from three literature cases of different scales.

Fulbright Program: A Bright Facet of Sino-U.S. People-to-People Exchange

In the history of Chinese-American people-to-people exchange,the implementation of the China-U.S.Fulbright Program is surely a bright facet which should not be ignored.This program has been cultivating talents in the fields of social sciences and humanities for the two countries,promoting Sino-U.S.communications in the domains of education,academia and culture,and propelling the diffusion and advance of both Chinese and American cultures.The Fulbright Program in China still has certain limitations waiting to be improved,and one obvious problem is its coverage in China.To solve this problem,more Chinese higher education institutions should be included in the China-U.S.Fulbright Program,and the result would be the generation of immeasurable value for the prosperity of Sino-American people-to-people exchange and therefore the construction of the new model of major country relations between China and the United States.

Simulated Annealing Approach to the Optimal Synthesis of Distillation Column with Intermediate Heat Exchangers

This article presents a simulated annealing-based approach to the optimal synthesis of distillation column considering intermediate heat exchangers arrangements. T-he number of intermediate condensers and/or intermediate reboilers, the placement locations, the.operating pressure of column, and the heat duties of intermediate heat exchangers are treated as optimization variables. A novel coding procedure making use of an integer number series is proposed to represent and manipulate the structure of system and a stage-to-stage method is used for column design and cost calculation. With the representation procedure, the synthesis problem is formulated as a mixed integer nonlinear programming （MINLP） problem, which can then be solved with an improved simulated annealing algorithm. Two examples are illustrated to show the effectiveness of the suggested approach.

Study on Multi-stream Heat Exchanger Network Synthesis with Parallel Genetic/Simulated Annealing Algorithm

The multi-stream heat exchanger network synthesis (HENS) problem can be formulated as a mixed integer nonlinear programming model according to Yee et al. Its nonconvexity nature leads to existence of more than one optimum and computational difficulty for traditional algorithms to find the global optimum. Compared with deterministic algorithms, evolutionary computation provides a promising approach to tackle this problem. In this paper, a mathematical model of multi-stream heat exchangers network synthesis problem is setup. Different from the assumption of isothermal mixing of stream splits and thus linearity constraints of Yee et al., non-isothermal mixing is supported. As a consequence, nonlinear constraints are resulted and nonconvexity of the objective function is added. To solve the mathematical model, an algorithm named GA/SA (parallel genetic/simulated annealing algorithm) is detailed for application to the multi-stream heat exchanger network synthesis problem. The performance of the proposed approach is demonstrated with three examples and the obtained solutions indicate the presented approach is effective for multi-stream HENS.

Impacts of Exchange Rate Volatility and FDI on Technical Efficiency—A Case Study of Vietnamese Agricultural Sector

The objective of this research is to examine impacts of exchange rate volatility and FDI on efficiency of the Vietnamese agricultural sector at the provincial level for the period 1998-2011. Due to the characteristic of high uncertainty in agricultural production, the chance-constrained programming model would be used to estimate efficiency of the agricultural production sector. In order to study impacts of exchange rate volatility and FDI, we employ the two-stage model. In the first stage, we use the chance-constrained programming model to measure technical efficiency and ARIMA model to quantify exchange rate volatility. In the second stage, we use the fixed effect model to evaluate impacts of exchange rate volatility and FDI on efficiency of agricultural production in poor and rich provinces. The estimated results show that fluctuation in exchange rate volatility would reduce efficiency in agricultural production but FDI has an insignificant impact on the efficient production in Vietnam agricultural sector.

International Exchanges by College Nursing Students: “International Comparisons of Awareness and Challenges”

Aim: The aim of this study was to determine the extent of awareness of international exchanges among college nursing students in Japan and other countries and to identify strategies to improve awareness. Method: This is an integrative literature review, consisting of scientific articles published on “Ichushi-Web,” an Internet-based retrieval service by the Japan Medical Abstracts Society (JAMAS) and Google Scholar for domestic documents and, PubMed, Medline, Cochrane library and Google Scholar for foreign documents. We employed search parameters for “the years from 2000 to 2017” in combination with “international educational exchange”, “schools, nursing”, “students, nursing”, “program evaluation”, and “awareness.” Result: The data were extracted from seven documents among a review of 29 retrieved domestic documents written in Japanese, and another seven documents among a review of 111 retrieved foreign documents written in English. All documents from Japan were reports of quantitative studies, and most documents from other countries were qualitative studies. The data from Japanese research reports were classified into four perspectives: interest in international exchange, need to participate in international exchange, understanding of different cultures and awareness of foreign settlers. The data from research reports from other countries were classified into three perspectives: understanding of different cultures, improving expertise in nursing, and awareness of the international community. Conclusions: Strategies that will enhance students’ understanding of diverse cultures are needed to increase their awareness of international exchanges.

Microsoft EXchange是否支持在Hyper-V上运行？

微软在2008年8月19日发表声明，ExchageServer2007SPs1支持在WindowsServer2008Hyper—V和其它属于Microsoft Server Virtualization Validation Program一部分的虚拟控制程序上运行，关于这一点，大家请参考MicrosoftExchangeTeam博客的文章：http：//msexchangeteam．com／archive／2008／08／19／449621．aspx。大家可以在以下地址找到更多关于MicrosoftExchange的虚拟化支持策略的内容：http：//technetmicrosoftcom／en-us／library／cc794548．aspx。

高等教育在地国际化:意涵阐释、全球案例与中国借鉴

高等教育国际化是教育对外开放的鲜明特征,以跨境流动为主的高等教育国际化模式面临危机,学界将更多关注在地国际化模式。在地国际化致力于培养全体学生的跨文化交流能力,提升高等教育机构的国际治理能力,通过增强机构的文化多样性,提供文化敏感的国际化课程,加强国家间的对话与共享。全球主要国家通过国家战略、机构策略、国际课程、学生融合等方面实施在地国际化。我国在地国际化实践进入了新的历史阶段,但仍面对挑战。我国高等教育国际化在“弯道超车”和“变道超车”的过程中,应取人才培养本位,促知识流动、引战略转型;增强“本土留学”服务能力;创建富有中国特色的国际化校园环境,重塑国际化课程模式和实践;实施文化敏感的教学,加强文化引领;以微证书项目促进在地国际化的“流动性”。

Study of the Temperature-Programmed Desorption of Carbon Dioxide (CO2) on Zeolites X Modified with Bivalent Cations

Study of physisorbed and chemisorbed carbon dioxide (CO2) species was carried out on the NaX zeolite modified by cationic exchanges with bivalent cations (Ca2+ and Ba2+) by temperature-programmed desorption of CO2 (CO2-TPD). Others results were obtained by infrared to complete the study. The results of this research showed, in the physisorption region (213 - 473 K), that the cationic exchanges on NaX zeolite with bivalent cations increase slightly the interactions of CO2 molecule with adsorbents and/or cationic site. Indeed, the desorption energies of physisorbed CO2 obtained on the reference zeolite NaX (13.5 kJ·mol-1) are lower than that of exchanged zeolites E-CaX and E-BaX (15.77 and 15.17 kJ·mol-1 respectively). In the chemisorbed CO2 region (573 - 873 K), the desorption energies related to desorbed species (bidentate carbonates: CO32-) on the exchanged zeolites E-CaX and E-BaX are about 81 kJ·mol-1, higher than the desorbed species (bicarbonates: HCO32-) on the reference R-NaX (62 kJ·mol-1). In addition, the exchanged E-BaX zeolite develops the secondary adsorption sites corresponding to bicarbonates species with desorption energies of 35 kJ·mol-1 lower to desorption energies of bicarbonates noted on the reference zeolite NaX.

高等院校跨地域间校际交换培养模式探索

交换培养模式不论是在本科阶段还是硕士研究生阶段,都是高校联合培养人才的途径之一。对于人才培养的全新探索,交换生的培养模式必然成为每所高校都要探究的新课题。该文阐述大学期间跨地域间的校际交换培养的意义,探讨影响高校跨地域间校际交换模式的诸多教育问题,并提出完善校际间交换生教育和培养模式的对策。

融合原子交换特征信息的代谢路径预测

为获取从任意起始代谢物到目标代谢物的生化相关性较好的代谢路径,提出一种融合原子交换特征信息的基于约束的代谢路径预测算法PVA。结合代谢网络中具有的原子交换特征信息,建立一种基于约束的混合整数线性规划(MILP)代谢路径预测模型,以搜索从任意起始代谢物到目标代谢物并包含特定原子交换信息的代谢路径。实验结果表明,与同类方法相比,PVA能够有效地发现生化相关性更好的代谢路径。

基于数据交换格式标准的通用一致性测试框架

基于数据交换格式标准的通用一致性测试框架首先需要研制一致性测试标准,再由测试开发人员依据一致性测试标准,完成数据格式标准文本形式到程序可读文件形式的转化及一致性测试系统的设计和开发,最终以程序可读文件作为基准测试用例集,以导出软件导出的被测文件为被测件,通过对结构、语法的分析完成一致性测试。通用测试框架通常不关注具体的标准,只需依据一致性测试标准提炼通用结构分析和语法分析规则,维护基准测试用例集,代码开发量有效降低,测试人员可以快速完成对测试需求的支撑。

电力通信程控交换系统组网技术方案研究

程控交换技术具有稳定性高、支持多种通信协议以及自动接通等功能,将其用于电力通信网络,能够提升电力通信稳定性和并网效率。文章基于通信程控交换技术,结合某电力企业要求,设计程控交换系统接入方式、服务器、网络及并网安全防护,实现稳定高效通信,以期为相关工作者提供参考。

碳交易规制下的共享电动汽车充放电优化

针对当前电网负荷压力大及调峰困难等问题,以换电模式下共享电动汽车作为研究对象,提出了参与碳交易市场和调峰辅助服务市场的电动汽车充放电优化模型。上层模型以电动汽车运营商日运营成本最小为目标对电动汽车进行充放电调度,下层则以电网负荷波动最小为目标对上层的调度结果进行优化。从电动汽车运营商和电网两个角度对比分析了该文所提的充放电方案,并且将一个运行周期内电动汽车运营商与燃油汽车运营商所产生的碳排放量进行比较。仿真结果表明:所提模型可以在满足用户出行需求的同时,降低运营商的成本,同时减小电网负荷波动。

“汉语桥”线上团组交流项目学习满意度调查分析——以天津外国语大学为例

2020年,在新冠疫情席卷全球的大背景下,教育部中外语言交流合作中心面向全球中文爱好者推出了“汉语桥”线上团组交流项目。该项目通过线上教学的方式,旨在满足海外学生了解中国语言文化的需求,使其在学习中文的同时通过云端领略中国文化。以天津外国语大学面向哥伦比亚各高校大学生举办的“汉语桥”线上团组交流项目为例,对该项目的学习满意度进行调查分析,为“汉语桥”线上项目更好地运行提供解决方案。

Fault-Tolerant Communication Network System for the Super Stored Program Control Exchange

With the increasing popularity of the computer network, more and more attention is paid to the reliability of the network. To improve the reliability of the communication network in the stored program control exchange, the author propounds a redundant method supported by a kind of the double local area network. Fault detection, hardware switching and system rebuilding are processed automatically by the administration of the software. The method can improve not only the system′s reliability but also its communication efficiency. It has been implemented in the pSOSystem environment in a super stored program control exchange.

高校涉外法治人才培养体系的完善对策

在我国推进高水平对外开放和全面依法治国背景下,国家对涉外法治人才培养提出了更高的要求。高校作为涉外法治人才培养的基地,在其中担负着重要使命。经过多年来的努力,国内诸多高校在涉外法治人才培养领域已经取得了一定的成绩,但仍面临着短期内无法填补涉外法治人才巨大缺口的社会现实。目前高校的涉外法治人才培养体系存在理论教学与实践脱节、学习内容滞后、语言障碍严重三大不足。为此,国内高校有必要从加强培养学生的法律外语综合应用能力、为学生搭建国际化的实习平台、开发更多的国内外法学院交换项目、加强培养学生的法治思维四个方面进行改革创新,真正形成完备的高校涉外法治人才培养体系,系统且有效地培养涉外法治人才,以满足国家在国际治理和涉外工作中的需求。

What They Learned Won't Go Away:The Impacts ofan International Exchange Program on Chinese Teacher Candidates' Understanding of and Practice in Science Education

Purpose:The Canadian university where this study took place has established an international exchange program in teacher education with a large Chinese university.This study was designed to examine how the international exchange program influenced Chinese science teacher candidates'understanding of science education and how such learning impacted their teaching in China.Design/Approach/Methods:The study adopted a qualitative research design with interview and reflective journal as the main approaches for data collection.Findings:Participants greatly appreciated the opportunity of exchange.They reported an improved understanding of Canadian school education and its science curriculum and pedagogy,which changed many aspects of their original values about the relationship between the teacher and students,classroom environment,and so on.Although they faced many constraints to implement what they learned from the exchange in Chinese science classrooms,what they learned had never been forgotten.Participants tried to apply them here and there at the level they could control.Originality/Value:There are many reported studies in the literature about Chinese international students on Western campuses.However,research on Chinese students who participate in international exchange programs is very rare.The findings of this study can inform policymakers and education practitioners about student international exchange programs and benefit future exchange participants.

留美幼童的多重面向:以容揆为例的分析

留美幼童是近代中国走向世界过程中的重要群体,而容揆则是其中较为特殊的一个。与其他官派留美幼童不同,容揆在1880年因入教、剪辫、逃跑等事件,与“幼童出洋肄业局”决裂,因此避免了在次年与其他留美幼童一起撤回国内的命运,并在容闳的资助下顺利完成了耶鲁大学和哥伦比亚大学的学业。作为自由职业者,深受美国文化影响的容揆,却在美国排华盛行的环境中坚持传播中国文化,并尽力帮助当地华人社群。作为职业外交官,容揆在驻美使馆近半个世纪的工作中,亲历了许多重要的外交事件,同时也在侨务工作和留学生教育事业上颇有贡献。容揆的经历也具有其普遍性:以他为代表的留美幼童是这一时期中西交流的桥梁,他的经历也是官派留学生和外交官群体的典型写照。这些都反映出留美幼童在时代浪潮中的多重面向。

人工智能与数学规划的集成用于换热网络最优合成设计的研究

用人工智能与数学规划的集成方法，对换热网络进行同步最优合成设计，建立了换热网络结构和匹配单元同时优化的数学模型，并提出运用分解协调法求解该模型。该方法不仅能自动地合成换热网络的最优流程结构，而且能同时满足网络的各种工艺限制条件。通过某个换热网络的最优合成设计，说明本方法的有效性和应用前景。