1,1—二氯—2—乙氧基—2—芳基烯烃质谱开裂机理探讨

本文报道通过亚稳离子和精确质量测定,讨论了1,1—二氯—2—乙氧基—2—芳基烯烃的质谱裂解规律。提出了主要是经过McLafferty重排,再经过1,3—氢迁移的机理。     

IMTS 2006——Equipped For a Strong Manufacturing Future

瞬息万变的全球市场往往被比作工业革命。在工业革命的影响下,一个国家的经济基础由以手工劳动为主转变为以电力驱动的机器为主,机床的发展也作为一项创新技术使人们能更轻易地完成工作。这些重大变化都发生在当今大规模产业转型期内。目前,美国公司面临的一个最大挑战是在设备和工艺落后的条件下还要不断满足国际市场的蓬勃发展,这加大了其投资的风险。因此,他们改革的步伐逐年加快,有竞争优势的领导厂商也尽力去履行不断改进制造技术、增加产量、提高质量和降低劳动成本的承诺。与此同时,美国制造业继续保持对新设备的高需求量,如今年头4个月,美国制造技术的消费就提高了18%,制造技术需求已经连续第三年保持增长,消费量较2005年增长8%,较2004年增长43%,美国制造业产出量达到了历史最高点。在全球信息爆炸性增长的今天,企业应把精力集中在9月6日至13日在芝加哥举办的“国际机床制造技术展览会”那些新的、改良的以及领先的产品上。IMTS2006的参展商数目比以往有所增长,1300多个厂商建立起了120万平方英尺的展示空间——美国制造业继续表现出他们对新装备的巨大需求,体现在今年第一季度消费增长了22%。     

HFC—134a状态方程的比较

本文论述了ＨＦＣ－１３４ａ状态方程的发展，对几个重要的方程式与实验数据进行了比较，发现Ｐｉａｏ方程式是工况范围内最佳关系式。     

FuncDesigner—a functional design software system

Engineering design focuses on the development of products and artefacts to satisfy the specified function. Although considerable advances have been made over the last two decades in functional modelling, there is not very much progress on commercial Computer-Aided Design (CAD) systems that really aid the designer in converting functional specifications to concept variants. Based on our previous work on Behaviour-driven Function-Environment-Structure (B-FES) modelling framework, this paper presents a functional design software system, called "FuncDesigner", to support the functional design of mechanical products through functional reasoning steps, including causal behavioural reasoning and functional decomposition. A function object library and a behaviour object library have been developed as well to serve as the knowledge base for the computerised functional modelling environment. The proposed functional design software system has been evaluated with a design example of a terminal insertion unit in an automatic assembly system for manufacturing electronic connectors.     

SIBS — a job shop simulation-based scheduler

The problem of finite capacity short-term scheduling in a modern CNC job shop is addressed. The application is an Israel Aircraft Industries (IAI) plant which is conceptually designed as a manufacturing cell. The cell contains six very large (bed length 451–452 inch) 3-head spindle, 5-axis CNC milling machines. A simulation-based scheduler based on SIMAN (a general purpose simulation package) is presented as the means for generating schedules. It is shown that shop performance measures such as lead times, throughput and machine utilizations are improved by an order of 30%, which represents a substantial saving due to the increased capacity of the manufacturing cell.     

The efficiency of a hypoid axle—a thermally coupled lubrication model

The final drive unit in road vehicles, such as medium and heavy trucks, and four-wheel-drive and rear-wheel-drive passenger cars, usually consists of a hypoid or spiral bevel geared transmission and differential, housed in a self-contained, dip-lubricated axle. Such units are subjected to very variable duty—including extreme combinations of speed, gradient, applied torque and external temperature—and are typically cooled by natural and forced convection on the exterior surface. On the other hand, there are appreciable internal power losses due to gear friction and churning and to bearing and seal losses. These losses are highly dependent upon the lubrication regime of the internal components and hence to the thermal behaviour of the entire axle.In the present paper, we describe a thermally coupled model of axle lubrication. The torque and speed demand is first found from a specified duty (“drive cycle”) which includes terrain as well as speed-versus-time and external temperature data. The evolution of sump oil and component temperatures is followed, and increments of energy loss evaluated in each time-step. Elastohydrodynamic film thickness is determined for the hypoid gear set, using a development of Buckingham's method, and friction losses calculated using a simple oil rheological model based on tribometer (MTM) testing. Churning, seal and bearing (speed-dependent) losses are found using empirical algorithms. Energy losses over complete drive cycles for different lubricants are derived, enabling the relative fuel economy for different oils to be evaluated.Results show that (i) the bulk temperature rise of the axle is highly dependent on the specified vehicle duty and (ii) the efficiency can be strongly influenced by choices available to the lubricant formulator. Taken together, these findings suggest that specialist axle lubricant formulations for particular vehicle types and applications will be attractive as a route to optimum fuel economy.     

RD—4a氢分析器的改制

根据生产需要,利用库存材料,以RD-4a氢分析的图纸和有关资料为基础,改制成功RD-4a氢氮比分析仪,装在现场使用,指示准确,灵敏可靠,反映良好。 1.原RD-4a氢分析器的三大部分中,予处理部分是分析室库存的一些玻璃器皿组装成的。现将传送器和二次表的更改和代替情况说明如下。二次表是用一块毫伏计代替了原二次表     

Shopfloor programming — a concept supporting skill-based manufacturing

German-speaking countries have a long tradition of skill-based manufacturing. Within the German dual system of vocational training, production workers are provided with a high degree of qualifications, experience, and skills. Nowadays, however, advances in technology and the increasing use of numeric control for machine tools and other types of production machinery are major factors endangering this tradition. It is therefore of particular interest to investigate the extent to which forms of shopfloor programming are applied which can help to stabilize or even increase production workers' skills and qualifications, thus preserving their ability to work autonomously.     

Planning for integration — a data oriented approach

To achieve succesful integration in a CIM environment the planning process should be based on a data oriented approach. This involves the construction of a strategic data model which shows the key entities and data relationships within the organization. Through the identification of business objectives, and the application systems which support them, the data model provides a stable foundation on which to build an integrated environment. Fundamental to the planning process is the premise that a data model is stable whilst application processes are volatile and indeed should be designed to be flexible.     

Influence of friction during forming processes—a study using a numerical simulation technique

Friction has an important influence in metal forming operations, as it contributes to the success or otherwise of the process. In the present investigation, the effect of friction on metal forming was studied by simulating compression tests on cylindrical Al-Mg alloy using the finite element method (FEM) technique. Three kinds of compression tests were considered wherein a constant coefficient of friction was employed at the upper die–work-piece interface. However, the coefficient of friction between the lower die–work-piece interfaces was varied in the tests. The simulation results showed that a difference in metal flow occurs near the interfaces owing to the differences in the coefficient of friction. It was concluded that the variations in the coefficient of friction between the dies and the work-piece directly affect the stress distribution and shape of the work-piece, having implications on the microstructure of the material being processed.     

Composite fabrication using friction stir processing—a review

Composite manufacturing is one of the most imperative advances in the history of materials. Nanoparticles have been attracting increasing attention in the composite community because of their capability of improving the mechanical and physical properties of traditional fiber-reinforced composites. Friction stir processing (FSP) has successfully evolved as an alternative technique of fabricating metal matrix composites. The FSP technology has recently shown a significant presence in generation of ex situ and in situ nanocomposites. This review article essentially describes the current status of the FSP technology in the field of composite fabrication with the main impetus on aluminum and magnesium alloys.     

Tribology,lubricants and lubrication engineering — a review

In this review paper more than 200 papers published between 1974 and 1976 are evaluated. These papers deal with the fundamentals of friction, wear and lubrication, including the state of friction, lubrication and materials. Another important subject is the analytical data and properties of mineral oil and synthetic lubricants, lubricating greases, additives and solid lubricants. Lubrication systems and lubricating devices as well as the lubrication of bearings, gears and internal combustion engines are also covered. Lubricants for machining processes and for metalworking are reviewed, as well as questions concerning the testing and evaluation of lubricants.     

Thermohydrodynamic Analysis of a Journal Bearing in a Turbulent Flow Regime—Part I: Theory

An attempt is made to formulate a thermohydrodynamic model of fluid-film lubrication that is valid in turbulent flow regimes. The model considers the flow to be a small perturbation of turbulent Couette flow. The modified Reynolds equation is obtained for the turbulent flow and the integro-differential energy equation makes the turbulence analysis easier by replacing the conductive terms in terms of the convective boundary conditions at two solid surfaces. Sample results applying the perturbation method agree well with available experimental data and theoretical methods.     

Optimization of sand-casting process variables—a process window approach

The present competitive market focuses on producing high-quality products with the lowest possible cost. To help accomplish this objective, various quality-enhanced tools have been put forward in recent years and, of these, process window approach (PWA) has emerged as perhaps the most viable and efficient technique for process quality improvement. The PWA is a powerful tool for quickly optimizing and confirming the quality and robustness of a process setup for any parameters. The work in this paper focuses on implementing a proposed PWA in order to optimize the sand-casting operation variables. In this research, the authors have kept their prime focus on minimizing the defects developed in the sand-casting process by PWA. Analysis of various critical process parameters and the interaction among them is carried out with the help of Taguchi method of experimental design. To optimize the results obtained and to make the analysis more precise and cost-effective, response surface methodology (RSM) is also incorporated. The optimized parameters obtained using the Taguchi method and RSM are then tested in an industrial case study. It is validated by proposed process window approach.     

Vegetable oils as a potential cutting fluid—An evolution

A review is made here to understand the application of vegetable oils as potential metal working fluids. The study highlights the contributions from more than sixty authors on vegetable based oils as emerging environmental friendly cutting fluids. The performance of these oils as emulsions and straight oils for various materials and machining conditions are reported. The study focuses on the evolution of vegetable oils as cutting fluids in manufacturing sector, particularly, metal cutting and metal forming.It is observed that, most of the contributions are directed to develop and commercialise the cutting fluids based on vegetable oils. However, soyabean, sunflower and rapeseed seem to possess the relevant properties as a potential cutting fluid.     

Variable amplitude fatigue crack growth behavior — a short overview

A short overview concerning variable amplitude (VA) fatigue crack growth behavior is presented in this paper. The topics covered in this review encompass important issues pertaining to both single and repeated overload transients. Reviews on transient post overload effects such as plasticity induced crack closure, crack tip blunting, residual stresses, crack deflection and branching, activation of near threshold mechanisms, strain hardening are highlighted. A brief summary on experimental trends and finite element modelling of overload induced crack closure is also presented.     

Optimization of roll forming process parameters—a semi-empirical approach

The roll forming process parameters play a major role in the quality of the final roll-formed product. Optimum configuration without any cost increase in the roll forming line could present accurate and flawless products. In this paper, a roll forming process experimental modelling of a symmetrical U-section profile from advanced high strength steel (AHSS) material (type DP600) is presented. The factors selected for this study are the roll forming line velocity, the inter-distance between roll stations, the roll gap, and the diameter of the rolls. An optimization procedure for the roll forming line, via statistical design of the experimental simulation runs, is also presented. The optimum values of process parameters are calculated for minimum elastic longitudinal strains and shear strains, at strip edge, for each roll station. A reduction of 20–35% in elastic longitudinal strains could occur for all roll stations, and 30–50% reduction in shear strains occurs for roll stations with a greater folding angle, as this leads to roll-formed products of a better quality. Finally, the contribution of each factor on the longitudinal and shear strains has been calculated, showing that the inter-distance between the roll stations plays a dominant role in the roll forming process.     

灰色无偏GM(1,1)理论应用研究

利用灰色理论，通过研究建立了无偏的GM(1，1)模型，突破了模型参数|α|较大时GM(1，1)模型无法应用的禁区，并将无偏GM(1，1)用于对齿轮磨损数据的预测，通过实验研究获得了满意效果，为齿轮磨损趋势的预测提供了一个新方法。