Co-Mo-K催化剂上COS、HCN转化率的热力学分析

利用热力学基础数据和相关软件对Co-Mo-K催化剂上COS、HCN加氢和水解反应进行了热力学计算。在热力学上,COS、HCN加氢和水解反应在耐硫变换条件下均为自发过程。计算结果表明在Co-Mo-K耐硫变换条件下COS、HCN主要发生的是水解反应,该结果与工业经验数据基本一致,可以作为工业实际借鉴。     

Cu/ZnO/Al_2O_3甲醇合成催化剂AsH_3中毒热力学分析

利用HSC热力学软件对Cu/Zn O/Al_2O_3甲醇合成催化剂As H_3中毒热力学进行了计算。分析了在150°C~300°C的合成温度下催化剂可能发生的化学反应,并比较各自发反应的化学平衡常数。结果表明:合成原料气组分(CO、H_2O、N_2、O_2)能引起催化剂砷中毒。其中,O_2对催化剂砷中毒的影响最大,参与反应的热力学竞争力最强,产物Cu_3As、As_2O_5、As_2O_3和Cu_3(AsO_4)_2可能导致催化剂失活。为应对砷中毒,应在合成反应之前深度净化合成气。     

F-T合成中脱氧反应的Monte Carlo模拟研究

本文用Monte Carlo模拟方法从微观角度研究了脱氧反应速率对F-T合成反应的影响.结果表明当CO2生成速率增加时,催化剂表面H物种的覆盖度随之增加,提高F-T反应的活性,降低C2产物的选择性;当H2O生成速率＜10-3时,催化剂表面CO的覆盖度增加,促进F-T反应活性.当H2O的生成速率＞10-3时,由于表面H物种覆盖度降低,使得F-T反应活性降低.C2产物的选择性增加.通过对脱氧反应与F-T反应的相互影响进行研究,揭示了脱氧反应与F-T反应活性、选择性的影响,从而对催化剂研发、工艺条件选择提供了一定的理论指导.     

钴基催化剂F-T合成的人工神经网络模拟

反应温度、压力、空速和原料气H_2/CO比等工艺操作条件对F-T合成生成重质烃的选择性影响很大。以上述操作参数为输入变量,CO的转化率、甲烷在产物烃中的质量分数C_1和重质烃的质量分数C_5~ 为输出变量,采用LM算法建立了钴基催化剂F-T合成的BP神经网络模型,定量预测工艺操作条件对F-T合成的影响规律。预测结果表明,低温有利于重质烃生成,高温下CO的转化率高,但C_1也高,C_5~ 重质烃的选择性较低。压力升高,C_1下降,CO的转化率和C_5~ 增加。C_1随空速的提高而增加,CO的转化率和C_5~ 随空速的升高而下降。低合成气H_2/CO比CO转化率和C_1较低,C_5~ 重质烃高。进一步的实验验证表明,模型具有较高的预测精度,CO转化率和C_5~ 的相对误差小于8%,C_1小于9%。     

H_2M(CO)_4(M=Fe,Ru,Os)···CH_3OH/H_2O中弱相互作用的理论研究

金属氢化物因其在有机化学、药物化学及工业生产中发挥着重要作用而备受关注。本文利用量子化学计算方法,使用w B97xd密度泛函,Ru和Os原子采用aug-cc-pVDZ-PP、其它原子采用aug-cc-pVDZ基组,对由金属氢化物H_2M(CO)_4(M=Fe,Ru,Os)和常见小分子CH_3OH/H_2O间形成的复合物H_2M(CO)_4…CH_3OH/H_2O(M=Fe,Ru,Os)中的弱相互作用进行了研究。采用电子密度拓扑分析方法分析了复合物中MH…H键键的作用本质。计算结果表明,此类MH…H相互作用属于闭壳层弱相互作用;对于相同的电子给体,H_2M(CO)_4(M=Fe,Ru,Os)与CH_3OH形成的MH…H作用要强于其与H_2O形成的MH…H作用;对相同的电子受体,MH…H相互作用的强度按照M=Fe,Ru,Os的顺序依次增强。     

山梨醇与对甲基苯甲醛合成山梨醇缩醛反应的热力学分析

分析和计算山梨醇与对甲基苯甲醛合成山梨醇缩醛反应的热力学对于开发该反应的催化剂和反应工艺具有重要意义。首次利用Benson法计算了山梨醇一缩对甲基苯甲醛(MPBS)、山梨醇二缩对甲基苯甲醛(DPBS)和山梨醇三缩对甲基苯甲醛(TPBS)的热力学参数,建立了MPBS、DPBS和TPBS的热容与温度的关系方程。在此基础上,利用Kirchhoff方程,分别建立了山梨醇与对甲基苯甲醛缩合为MPBS、DPBS和TPBS 3个反应的焓变与温度的关系方程,计算表明在300 K～1000 K温度范围内,山梨醇与对甲基苯甲醛缩合生成MPBS、DPBS和TPBS的3个反应均为放热反应。     

硫醇类硫化物与H+相互作用的分子模拟

为了研究催化裂化、加氢等工艺过程中,硫醇类硫化物与固体酸性催化剂的B酸中心之间的相互作用机理,采用动力学和半经验量子力学方法,对几种典型硫醇类硫化物与H+之间的相互作用进行了研究.以2-戊硫醇、环己硫醇和硫酚为模型化合物,模拟计算了各硫醇类硫化物的最高占据轨道(HOMO)以及H+进攻硫位及不同碳位时所形成中间体的生成热及键长变化,进而讨论H+的优先进攻位置以及反应中间体的稳定性.结果表明,H+的进攻位置对形成的中间体的稳定性有很大影响.当H+进攻硫醇类硫化物中的碳位时,反应中间体的生成热远大于或接近于H+直接进攻硫位所形成的中间体的生成热;对于反应中间体的生成热同进攻硫位所形成的中间体的生成热相近的碳原子上的质子化反应,其实质与直接进攻硫原子时相一致,并生成硫化氢,这说明H+将优先进攻硫醇类硫化物中的硫原子.由此可以认为,硫醇类硫化物在固体酸性催化剂的作用下,由于B酸中心的给质子性质,较容易在硫位上发生质子化反应,以生成硫化氢的形式转化脱除.     

苯与苯乙烯合成1,2-二苯乙烷反应的热力学分析

分析和计算苯与苯乙烯烷基化合成1,2-二苯乙烷反应的热力学,对于开发该反应的催化剂和反应工艺具有重要意义.本文利用热力学基本原理,首次建立了该反应的焓变及Gibbs自由能变化与反应温度的关系,建立了反应的平衡常数与苯乙烯平衡转化率的关系.结果表明,在标准状态下,该反应的△rH0m(298 K)=-87.088 kJ·mol-1,△rG0m(298 K)=-46.496 kJ·mol-1,反应为强放热自发反应;降低反应温度和提高反应压力,有利于提高苯乙烯的平衡转化率.     

硫化钼基加氢脱硫催化剂活性位的研究进展

硫化钼基催化剂是加氢脱硫过程的常用催化剂,其活性相结构与加氢脱硫性能的关系一直是催化加氢领域研究的热点问题,该问题对开发更高活性和选择性的催化剂具有十分重要的意义。本文综述了近年来加氢脱硫催化剂的表征和理论计算方面的研究进展,对MoS_2、CoMoS和NiMoS的具体微观结构进行了分析,并对可能的加氢脱硫活性位以及噻吩在活性位上加氢脱硫的反应路径进行了探讨。     

CoMoS催化剂中活性位形成的分子模拟研究

运用分子模拟计算方法建立了较为合理的CoMoS相簇结构模型,讨论了助剂Co的优先取代位置,在此基础上对CoMoS相催化剂几种主要活性位的产生位置及结构性质进行了比较系统的量子化学计算,以探索Co助剂对加氢脱硫催化剂结构的影响。计算结果表明:在通常加氢脱硫条件下Co会优先取代在角位和S边,并且角位和S边引入Co之后S空位的形成过程从热力学和动力学上都更具优势,即S空位的数量和循环产生速度均有所提升。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.