制备四氯化钛过程中加碳氯化反应热力学

反应热力学对研究二氧化钛加碳氯化反应具有指导作用。运用HSC软件通过计算对二氧化钛加碳氯化的CO／CO2比值、配碳比等进行了讨论,结果表明低温下加碳氯化反应的相关产物为CO2,而高温下为CO。产物TiCl4含量在整个温度范围内保持稳定。当配碳比较高时,碳的反应不完全,存在过量;较低时,不利于TiO2的完全反应。通过对工业TiCl4生产CO／CO2 比值研究,发现CO／CO2比值不完全与平衡态下的CO／CO2比值一致。同时对低价钛氧化物的生成进行了探讨,计算表明在温度低于1 100℃时不会生成低价钛氧化物。通过以上研究为进一步优化加碳氯化反应提供了依据。     

从面向过程到面向对象的变革

面向过程方法的弊端引发了20世纪60年代的"软件危机",面向对象方法的出现为软件开发开辟了新的出路。从分析"软件危机"的起因着手,阐述了面向过程方法的弊端,介绍了面向对象方法的特点,并总结了面向对象方法优越性和局限性。     

过程改进中评审活动的模拟分析

为定量研究评审效用,改进软件过程,通过模拟定量计算评审在过程改进中的效用。基于系统动力学方法分析评审活动和软件过程,建立软件过程模型。结合实例,证明了模型的正确性,通过模拟定量分析评审对项目工作量和工期的作用。模拟结果证明在一定范围内增加评审投入可以有效地增加工作效率,提高进度。以成本为优化目标,设置生命周期各阶段评审比例,通过自动模拟,得到最优评审工作投入,为实施软件过程改进提供量化支持。     

从概念程序表示到C++过程蓝图的映射

文章给出了与程序实现语言无关的概念层抽象逻辑结构图程序表示到C＋＋过程蓝图的平滑过渡方法和映射规则,给出了概念层和逻辑层抽象逻辑结构图的有效性定义、导出C＋＋逻辑层抽象逻辑结构图的有效性定理及其证明。     

基于纳米二氧化硅掺杂的丝网印刷碳糊电极葡萄糖生物传感器

研究了在丝网印刷碳糊电极上制作并改进生物敏感膜的过程,完成了基于纳米二氧化硅掺杂的用于测量人体血浆中葡萄糖浓度的生物传感器的制作.从酶促动力学原理分析了电极和生物敏感膜在各种实验参数优化前后的特性.实验证明:优化后的传感器灵敏度提高了2.6倍,检测范围为1.1～33.3 mmol/L,对测试范围内不同浓度的葡萄糖样本,相对标准偏差均＜5﹪,且稳定性良好,有较高的研究价值和应用前景.     

金纳米粒子自组装过程的动力学研究

将三种不同粒径的金纳米粒子组装到经1,6-己二硫醇修饰的金表面,借助于石英晶体微天平(Quartz Crystal Balance,QCM)实时监测金纳米粒子的自组装动力学过程,结合Michaelis-Menten动力学模型,并比较了相应的自组装动力学参数,从而得出金纳米粒子粒径大小对金表面粒子组装动力学的影响.实验表明,粒径较小的粒子形成单分子层的速率比粒径较大的粒子快,而形成多分子层的速率比粒径较大的粒子慢.这一结果对合理选择粒子大小进而制成性能优良的生物传感器具有重要的意义.     

VPML过程模型到面向对象Petri网模型的映射

为了支持对企业业务流程进行建模和分析,辅助过程改进,文章提出了用VPML语言建立过程模型.然后将该过程模型映射为面向对象Petri网模型,通过对Petri网模型的定性分析和模拟仿真,其结果可用于修正和改进模型设计.     

从故事到动画片--全过程计算机辅助动画自动生成

论述了作者提出并实现的全过程计算机辅助动画自动生成技术,即从用自然语言书写的故事开始,直至最终生成动画,每一步都是在计算机辅助下完成的,这是一种新的基于人工智能的动画生成技术.文中还分别从自然语言理解、故事理解、动画设计和生成、规划、动画知识库、常识处理几个方面对该技术进行阐述.     

甲醇及其衍生物低温氧化过程的热力学分析

利用HSC热力学软件对甲醇、甲醛、甲酸、O2、N2、CO2和H2O构成的多元、多相体系进行了热力学计算。从热力学角度看,在较低的温度下,甲醇、甲醛和甲酸更易被完全氧化成CO2和H2O而不是被部分氧化成其中间产物。同时,在270K温度下,甲醇、甲醛的转化率仍接近100％,因此,其氧化过程为动力学控制,使开发高效低温催化燃烧催化剂成为可能。     

基于系统动力学方法的软件过程建模与仿真

软件开发质量很大程度上取决于软件过程.软件过程涉及到众多相互关联和反馈的因素,特别是与人和组织行为有关的软因素,但在离散型传统建模方法中难以得到准确反映.文章介绍了基于系统动力学的连续型软件过程建模与仿真方法,并以Brooks法则作为实例描述了该方法的基本要素和优势.文章还对系统动力学方法应用于软件过程不同领域的研究加以回顾,并给出了今后的几个主要研究方向.     

溅射二氧化钛电极对过氧化氢电化学检测的研究

介绍一种使用微电子技术制造的二氧化钛电极,并且研究了该电极在磷酸缓冲液中的电化学特性。循环伏安法测量的结果显示,过氧化氢和氧气都能在该电极上还原,而且过氧化氢的还原更为明显。在磷酸盐缓冲液中,以Ag/AgCl为参考电极,当所施加电压为-300V时,安培法显示二氧化钛电极对过氧化氢有很快的响应速度,其对于0.1mmol/L过氧化氢的响应电流是0.4μA,而由于溶解氧所带来的背景还原电流仅为14nA。为了研究这种电极在生物传感器中的应用可能性,实验中把葡萄糖氧化酶固定在钛氧化物电极薄膜上并测试了相应特性,发现存在的主要问题为酶在氧化钛表面的固定较为困难。     

Numerical investigation of supersonic flow for axisymmetric cones

An existing curvilinear finite-volume code with robust shock-capturing scheme was modified to allow for simulations of supersonic flow for axisymmetric cone geometries. It is shown how for an axisymmetric coordinate system the convective and viscous flux derivatives in the circumferential direction reduce to a y-momentum equation source term. The advantage of this approach over an axisymmetric code is that the governing equations and the discretization do not need to be changed. This paper provides a detailed derivation of the axisymmetric source terms from the full Navier-Stokes equations. Results are shown for a sharp and a blunt cone for approach flow Mach numbers of M = 3.5 and M = 7.99.     

A Framework for Improving the Requirements Engineering Process Management

This paper presents a system dynamics model for improving the requirements engineering process management. The paper argues that improving RE process management improves the quality of the specification produced. It uses a simulation modelling approach to capture the complex and dynamic nature of quality and also the cost of resources and time needed to complete the process. Current claims by various researchers and empirical evidence has led to our proposition that “the earlier in the requirements engineering phase that system dynamics simulation modelling is used, the more effective the RE process management is and the better its product quality will be.” In developing such a model, the paper fills an important gap in the RE process management literature and has potential to provide requirement engineers, managers and software development organisations with a model-based process framework to aid quality assessment and improvement. The paper concludes by suggesting that the framework makes a useful contribution both in providing the foundations for theory building in RE process management and quality improvement by aiding shared understanding through learning and training situations. This revised version was published online in August 2006 with corrections to the Cover Date.     

On the limitations of software process assessment and the recognition of a required re-orientation for global process improvement

Through the years many techniques and tools have been tried and failed to deliver substantial global improvements to the software evolution process. The flavour of the early 1990s has been: attempted improvement using software process assessment methods such as CMM, BOOTSTRAP, etc. This paper represents a considerable and coherent critique of software process assessment as a process improvement driver, focusing on the concerns and perceived shortcomings present. A call is made to re-direct attention and resources towards understanding the true nature of software evolution and the software evolution process towards an adequate theory and practice for process improvement, all in order to save us from the computer. The important, possibly crucial role of feedback at many levels of the organizations that follow the processes that implement software development and maintenance is discussed. Utilizing some empirical findings in relation to software system evolution, it is suggested that the ignoring of feedback may be a major reason why the software process is so difficult to improve. It is argued that the clarification of such an important issue will help to achieve a significant step forward in process improvement, and through its exploitation, lead to significant improvements in quality, satisfaction and performance as well as more relevant education and training on process improvement.     

赤铁矿强磁选过程综合自动化系统

针对强磁选过程的特点及工艺要求,基于智能技术提出了实现工艺指标优化的强磁选过程综合自动化系统,讨论了由智能优化、过程控制和过程管理3层结构组成的综合自动化系统的结构、功能和控制策略。采用智能优化设定模型、反馈补偿器及回路控制系统实现了精矿品位、尾矿品位的优化控制。所提出的系统成功应用于某选矿厂强磁选生产过程,实现了强磁选过程的优化控制、优化运行和优化管理,提高了精矿品位,降低了尾矿品位,取得了明显的应用效果。     

Numerical investigation on the hovering performance of contra-rotating ducted rotor for micro air vehicle

Microsystem Technologies - In this study, the hovering performance of contra rotating ducted rotor (CRDR) for micro air vehicle (MAV) was performed by using computational fluid dynamics technique....     

Numerical algorithm for solving the problem of synthesis of impulse controls under uncertainty

Feedback control problem for a linear system under an unknown but bounded disturbance is considered. A numerical algorithm for the synthesis of controls in the problem of impulse control based on the representation of the value function using methods of convex analysis in terms of the conjugate function and the subsequent approximation of the conjugate function by piecewise affine convex functions is described.     

Thermodynamic investigation of KCl in the ternary KCl/LiCl/ H2 O mixed electrolyte system based on potentiometric method

The results of a thermodynamic investigation of KCl salt in the ternary KCl+LiCl+H₂O electrolyte system by potentiometric method are reported in this work. The experimental potentiometric data were obtained from a galvanic cell by combining a solvent polymeric (PVC) potassium-selective membrane electrode (K⁺ ISE), containing Valinomycin as ionophore, and an Ag/AgCl electrode. The measurements were performed, at similar constant ionic strengths, in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r$r$ (where r=_m1/_m2=0.1,0.2,1,5,10$r=m_1/m_2=0.1,0.2,1,5,10$, and _m1,_m2$m_1,m_2$ are the molalities of KCl and LiCl, respectively). The non-ideal behaviour of the system was described on the base of the Pitzer ion-interaction model for mixed salts, over the ionic strength ranging from 0.01 up to about 5 mol/kg, at 298.15 K. Based on the obtained Pitzer ion-interaction parameters, the osmotic coefficients, solvent activities, and excess Gibbs free energies were determined for these investigated ternary electrolyte systems.     

Enthalpy based modelling and design of asymptotic observers for chemical reactors

This article proposes to consider the basic thermodynamics based formulation of the energy balance equation for chemical systems with a limited number of simplifying assumptions. The objective is to show, via the design of one typical mass and energy balance state observer, how such design can be modified by considering the proposed thermodynamically based model formulation. The objective is also to emphasise the difference and the links between the energy balance-based temperature equation largely used in process control. The design of the asymptotic observer is illustrated with two examples: one CSTR in liquid phase and another one in gaseous phase.