并联机床的动力学特性对加工精度影响的分析

为了提高并联机床的加工精度,分析了并联机床的动力学特性对加工精度的影响。根据牛顿—欧拉方程,得到并联机床的动力学方程,解得连杆的驱动力;根据杆件轴向伸长量与受力之间的关系,得到连杆的长度误差;以无长度误差的连杆长度为优化目标,用优化的方法,得到动平台的位姿,并与连杆有长度误差时动平台的位姿比较,得动平台的位姿误差;根据刀具在动平台坐标系中位置,得刀具加工位置误差及对被加工零件精度的影响。结果表明：并联机床连杆的长度误差,引起刀具加工位置误差,使被加工零件产生形位误差和尺寸误差;并联机床电主轴偏心引起连杆的长度误差的扰动,产生刀具加工位置的扰动误差,影响被加工零件的表面粗糙度。     

Image segmentation of a color-blindness plate

One way of testing color vision is with a color-blindness plate (CBP) consisting of a set of brilliant colored dots to form a pattern (a figure) and a set of other colored dots to form a background. Classification of such a type of color image into a pattern and a background with a traditional technique is difficult. Based on a self-organizing feature map and a labeling process as well as spatial distance computation, an effective approach to the segmentation of a CBP image is presented. We describe the principle of a CBP segmentation and then introduce the CBP. The proposed approach is described, and its experimental results are presented. We conclude that the method can segment the CBP image into a pattern and a background successfully.     

A case-based reasoning approach toward developing a belief about the cost of concept

It is generally acknowledged that product development involves a sequence of decision making under uncertainty, including setting target requirements for a new product, selecting product concept, and developing conceptual and detailed design of a chosen concept. To select a product concept, engineers need to assess the uncertainty of a future market share, market size, and a cost of concept (cost of the final product developed from a concept). This paper proposes a case-based reasoning (CBR) approach to model beliefs about the uncertainty of a cost of concept. The proposed CBR approach consists of storing information about various products in a knowledge-base, defining a new product concept, retrieving a cluster of products in the knowledge-base that are highly similar to the concept, and adapting the cost of the retrieved product to construct a distribution of the cost of concept. This paper illustrates the proposed approach using printers as an example.     

Similarity solutions for slender dry patches with thermocapillarity

The lubrication approximation is used to investigate slender dry patches in an infinitely wide film of viscous fluid flowing steadily on an inclined plane that is either heated or cooled relative to the surrounding atmosphere. Four non-isothermal situations in which thermocapillary effects play a significant role are considered.Similarity solutions describing a thermocapillary-driven flow with a dry patch that is widening or narrowing due to either gravitational or surface-tension effects on a non-uniformly heated or cooled substrate are obtained, and examples of these solutions, when the substrate temperature gradient depends on the longitudinal coordinate according to a general power law, are presented. When gravitational effects are strong, the solution contains a free parameter, and for each value of this parameter there is a unique solution representing both a narrowing pendent dry patch and a widening sessile dry patch, whose transverse profile has a monotonically increasing shape. When surface-tension effects are strong, the solution also contains a free parameter, and for each value of this parameter there is both a unique solution representing a narrowing dry patch, whose transverse profile has a monotonically increasing shape, and a one-parameter family of solutions representing a widening dry patch, whose transverse profile has a capillary ridge near the contact line and decays in an oscillatory manner far from it.Similarity solutions are also obtained for both a gravity-driven and a constant-surface-shear-stress-driven flow with a dry patch that is widening or narrowing due to thermocapillarity on a uniformly heated or cooled substrate. The solutions in both cases contain a free parameter, and for each value of this parameter there is a unique solution representing both a narrowing dry patch on a heated substrate and a widening dry patch on a cooled substrate, whose transverse profile has a monotonically increasing shape.     

Fluctuational electromagnetic interaction between a moving particle and a flat surface covered with a thin adsorbed film

The effect of a thin adsorbed film on the fluctuational electromagnetic tangential force of interaction between a moving nanoparticle and a flat solid surface was theoretically studied for the first time in a nonrelativistic approximation. Particular calculations were performed for a metal film on a dielectric and for a dielectric film on a metal. In both cases, the nanoparticle is assumed to be made of a nonmagnetic metal. It is shown that, at a normal temperature, the presence of an adsorbed film may lead to an increase in the tangential friction force by one or two orders of magnitude for a certain relation between the particle distance from the surface and the film thickness. In the case of a dielectric film on a metal substrate, a decrease in the temperature is accompanied by exponential decrease in the viscous friction. For a metal film on a dielectric substrate, the tangential force exhibits a quadratic dependence on the temperature.     

A computer-assisted range image registration system for nuclearwaste cleanup

Building a three-dimensional (3-D) computer-based representation of a large or complex scene from a set of range images requires assembling the range images so that they are spatially registered. This paper will present a technique for finding a homogeneous transformation between a pair of range images while making use of both range and intensity information obtained using a laser range scanner. A demonstrated application featuring this technique consists of building a 3-D representation of a nuclear dumpsite, which then serves to help control a teleoperated nuclear waste remediation system     

Electrical switching of the vortex core in a magnetic disk

A magnetic vortex is a curling magnetic structure realized in a ferromagnetic disk, which is a promising candidate for a memory cell for future non-volatile data-storage devices. Thus, an understanding of the stability and dynamical behaviour of the magnetic vortex is a major requirement for developing magnetic data-storage technology. Since the publication of experimental proof for the existence of a nanometre-scale core with out-of-plane magnetization in a magnetic vortex, the dynamics of vortices have been investigated intensively. However, a way to electrically control the core magnetization, which is a key for constructing a vortex-core memory, has been lacking. Here, we demonstrate the electrical switching of the core magnetization by using the current-driven resonant dynamics of the vortex; the core switching is triggered by a strong dynamic field that is produced locally by a rotational core motion at a high speed of several hundred metres per second. Efficient switching of the vortex core without magnetic-field application is achieved owing to resonance. This opens up the potentiality of a simple magnetic disk as a building block for spintronic devices such as a memory cell where the bit data is stored as the direction of the nanometre-scale core magnetization.     

Formation of a Nanophase Wetting Layer and Metal Growth on a Semiconductor

Based on the data on the atomic density of a film and degree of its homogeneity during the formation of the interface between 3d transition metals (Cr, Co, Fe, or Cu) and silicon, a new concept of forming a contact between a reactive metal and a semiconductor has been justified. According to this concept, the low-temperature vapor-phase deposition of a metal onto a semiconductor is accompanied by the formation of a two-dimensional nanophase wetting layer of a metal or its mixture with silicon with a thickness of several monolayers, which significantly affects the interface formation and structure. This concept changes a perspective of forming a contact between a metal and a semiconductor substrate: it is necessary to take into account not only the formation of surface phases and clusters and/or the mixing process, but also the effect of elastic wetting of a substrate by the forming phases.     

The Variational Form of the Mathematical Model of a Thermal Explosion in a Solid Body with Temperature-Dependent Thermal Conductivity

The variational form of a mathematical model of a thermal explosion has been developed based on a variational formulation of a nonlinear problem of stationary thermal conductivity in a homogeneous solid body. The model takes the temperature dependence of the thermal conductivity of a solid body into account. The presented example of quantitative analysis of the model demonstrates a method for finding the combination of parameters for determining a thermal explosion in a plate with an exponential temperature dependence of the thermal conductivity. At the same time, the analysis allows one to identify the number of steadystate temperature distributions inside a body whose energy release intensifies with a temperature increase.     

Developing a product–service system through a productisation strategy: a case from the 3PL industry

A Product–Service System (PSS) is created by combing a tangible product and an intangible service into one integrated offering. Thus, a PSS can be achieved by a production company adding intangible services to a product using a servitisation strategy or by a service company adding a tangible product to a service by means of a productisation strategy. The focus of this paper is on the latter. Our work demonstrates a significant gap in the literature in this area. To address this, we adapt an existing PSS conceptual framework as a means to identify the driving and restraining forces considered by a service company as it explored the possibility of pursuing a PSS productisation strategy. The conceptual framework is applied in an exploratory case study with a 3PL service provider. Application of the framework reveals new driving and restraining forces not previously discussed in the literature. Furthermore, it allows a preliminary quantification of the driving and restraining forces using a force field analysis approach. Our work contributes towards the expansion of the empirical knowledge base in the area of PSS.     

Duangrit Bunnag

用“人生赢家”来形容Duangrit Bunnag不为过,伦敦AA建筑学院毕业生,在金融危机的谷底逆市创立设计公司,设计亚洲数一数二的漂亮酒店：他开的餐厅,常客名单里有维珍航空创始人RichardBranson：他的公司集群在一个5,000多平方米的旧工厂遗址上,设计公司、餐厅、书店、咖啡馆、家具贩售中心、画廊,店都是他的,地也是他的。     

Fabry–Perot interferometer in pulsed illumination: a new approach and capabilities

An analysis of the spectral-time characteristics of a Fabry–Perot interferometer (FPI) in pulsed illumination is given. Processes that occur in the transit of light pulses of different widths through a FPI are considered in detail. A relationship between the baseline of a FPI and the width of the incident light pulse is established. The time structure of a pulse that has traversed a FPI is analyzed. The theoretical difference in the transit of a light pulse through a FPI and of a regular sequence of synchronized laser pulses is found. The maximum time resolution of a FPI is determined. A model that describes the transit of a regular sequence of synchronized laser pulses through a FPI functioning in the mode of an optical filter is determined.     

Unstable resonator with reduced output coupling

The properties of a laser beam coupled out of a standard unstable laser resonator are heavily dependent on the chosen resonator magnification. A higher magnification results in a higher output coupling and a better beam quality. But in some configurations, an unstable resonator with a low output coupling in combination with a good beam quality is desirable. In order to reduce the output coupling for a particular resonator, magnification fractions of the outcoupled radiation are reflected back into the cavity. In the confocal case, the output mirror consists of a spherical inner section with a high reflectivity and a flat outer section with a partial reflectivity coating. With the application of the unstable resonator with reduced output coupling (URROC), magnification and output coupling can be adjusted independently from each other and it is possible to get a good beam quality and a high power extraction for lasers with a large low gain medium. The feasibility of this resonator design is examined numerically and experimentally with the help of a chemical oxygen iodine laser.     

A periodic pulsed relativistic backward wave oscillator mechanically tunable in an expanded frequency band

We have studied a periodic pulse train regime (1 s, 50 Hz) of a relativistic backward wave oscillator with a resonant reflector, which can be mechanically tuned from pulse to pulse within a frequency band of 9% on a level of ?3 dB of the maximum in the entire microwave peak power range in a magnetic field of 0.36 T. The maximum peak power in a pulse train amounted to 2.5 GW at a frequency of 3.6 GHz, an efficiency of 20%, and a microwave pulse duration of 20 ns.     

The operator tensor formulation of quantum theory

In this paper, we provide what might be regarded as a manifestly covariant presentation of discrete quantum theory. A typical quantum experiment has a bunch of apparatuses placed so that quantum systems can pass between them. We regard each use of an apparatus, along with some given outcome on the apparatus (a certain detector click or a certain meter reading for example), as an operation. An operation (e.g. B(b(2)a(3))(a(1))) can have zero or more quantum systems inputted into it and zero or more quantum systems outputted from it. The operation B(b(2)a(3))(a(1)) has one system of type a inputted, and one system of type b and one system of type a outputted. We can wire together operations to form circuits, for example, A(a(1))B(b(2)a(3))(a(1))C(b(2)a(3)). Each repeated integer label here denotes a wire connecting an output to an input of the same type. As each operation in a circuit has an outcome associated with it, a circuit represents a set of outcomes that can happen in a run of the experiment. In the operator tensor formulation of quantum theory, each operation corresponds to an operator tensor. For example, the operation B(b(2)a(3))(a(1)) corresponds to the operator tensor B(b(2)a(3))(a(1)). Further, the probability for a general circuit is given by replacing operations with corresponding operator tensors as in Prob(A(a(1))B(b(2)a(3))(a(1))C(b(2)a(3))) = ?(a(1))B(b(2)a(3))(a(1))C(b(2)a(3)). Repeated integer labels indicate that we multiply in the associated subspace and then take the partial trace over that subspace. Operator tensors must be physical (namely, they must have positive input transpose and satisfy a certain normalization condition).     

Dynamic stress intensity factors analysis of interface crack using line-spring model

In this study, a new method for calculating the dynamic stress intensity factors of a bimaterial bending specimen with an interface crack is proposed by making use of a line-spring model. A pre-cracked bending specimen is modeled by one-dimensional beam finite elements and a line-spring representing the stiffness or compliance of a cracked part. The proposed method enables the one-dimensional analysis of a two-dimensional crack problem; thus the time variations of the dynamic stress intensity factors of a bimaterial bending specimen with an interface crack can be obtained by making use of a personal computer within a few minutes. The results obtained by the proposed method agree reasonably well with those obtained by the two-dimensional finite element method, although a slight difference in period can be found. The proposed method enables rapid evaluation of dynamic stress intensity factors. So a rapid evaluation system of the dynamic fracture toughness of a bimaterial with an interface crack can be achieved by combining an instrumented impact test apparatus with a computer program based on the proposed method which runs on a personal computer.     

摩擦调节剂抑制钢轨波磨的机理研究

基于轮轨之间的摩擦耦合自激振动引起钢轨波磨的观点,论文建立了车辆稳态通过小半径曲线时由轮对－钢轨－轨枕组成的轮轨系统有限元弹性振动摩擦自激振动有限元模型,用ABAQUS软件对该模型的运动稳定性进行了分析,重点研究了轮轨摩擦系数和蠕滑力-蠕滑率曲线负斜率对轮轨系统摩擦自激振动的影响。计算结果显示,轮轨摩擦系数对轮轨摩擦自激振动有重要影响,当控制摩擦系数 时可以消除钢轨磨耗型波磨,蠕滑力-蠕滑率曲线负斜率对钢轨波磨有显著影响。     

Mutation-periodic quivers, integrable maps and associated Poisson algebras

We consider a class of map, recently derived in the context of cluster mutation. In this paper, we start with a brief review of the quiver context, but then move onto a discussion of a related Poisson bracket, along with the Poisson algebra of a special family of functions associated with these maps. A bi-Hamiltonian structure is derived and used to construct a sequence of Poisson-commuting functions and hence show complete integrability. Canonical coordinates are derived, with the map now being a canonical transformation with a sequence of commuting invariant functions. Compatibility of a pair of these functions gives rise to Liouville's equation and the map plays the role of a B?cklund transformation.     

Pd-C高温共晶点复现装置研制

主要针对Pd-C高温共晶点复现装置的组成进行介绍,其中包括复现用高温均热炉炉体、温度控制系统、真空泵、充气保护装置、水冷系统、复现用的石墨坩埚、二等B型标准热电偶和Pt-Pd热电偶等。针对石墨坩埚的灌注和共晶点复现过程进行了描述,根据复现的试验数据进行了相应的分析。