弹性半无限空间中矩形孔收缩的复变函数解答

随着城市建设的发展,矩形隧道的应用越来越多,但针对矩形隧道的理论研究却鲜有见闻。针对矩形隧道,建立了半无限空间矩形隧道的弹性理论计算模型,采用最小二乘迭代方法确定共形映射函数的各项系数,并将计算区域映射为复平面上的一个同心圆环;运用Muskhelishvili复变函数方法,将计算区域内的应力函数展开成为Laurant级数的形式,给定了地表零应力边界和矩形孔口径向位移边界,求得了半无限空间矩形隧道在给定位移条件下的应力场和位移场。分析了不同高宽比、不同泊松比、不同埋深对位移场和应力场的影响,总结了矩形隧道位移场和应力场的一般规律。结果表明：高宽比偏小、泊松比偏大、埋深偏小都会使得沉降槽不再是类高斯曲线的形状,这些参数的变化也会在不同程度上影响应力场和位移场的大小和分布。     

基于运动误差约束的平面定位平台拓扑优化设计

针对传统平面定位平台拓扑优化设计过程中无法预先了解输入输出位移映射矩阵的问题,基于固体各向同性材料惩罚法,采用遗传算法优化得到具有最大运动空间时的平面并联机构雅克比矩阵作为平面定位平台输入输出期望位移映射矩阵,在相同输入条件下,建立以机构实际运动与期望运动间误差最小为目标函数和以机构体积为约束函数的平面定位平台拓扑优化模型并求解。通过3D打印方式得到实验样品,实验与仿真分析表明:采用运动误差约束的平面定位平台拓扑优化设计方法,在一定偏差范围能够得到输入输出位移映射矩阵与给定期望映射矩阵相一致的平面定位平台,表明该方法对平面定位平台设计具备有效性,为其后续研究提供基础。     

无模多点成形中三维曲面工件的展开方法

本文从几何映射的角度出发 ,以面积不变为基本的展开原则 ,提出了适合于板材无模多点成形工艺的自由曲面展开的计算方法———三角形曲面片展开法和约束加权整体展开法 ,并用VC ++编制了相应的计算机程序。文中以鞍形样件和高速列车车头蒙皮的部分工件为例 ,进行了实际验算。     

面向网络化定制的产品族复合建模技术

在分析了网络化定制关键技术的基础上，针对性地对信息映射方法和产品族建进行了研究。提出了多层结构信息映射模型，以及综合类元件和参数化特征建模的双层复合产品族模型。结合本方法和以往网络化制造领域中所取得的成果，实现了较完整的基于Web的个性化定制过程。     

Past and future of software architectural decisions – A systematic mapping study

ContextThe software architecture of a system is the result of a set of architectural decisions. The topic of architectural decisions in software engineering has received significant attention in recent years. However, no systematic overview exists on the state of research on architectural decisions.ObjectiveThe goal of this study is to provide a systematic overview of the state of research on architectural decisions. Such an overview helps researchers reflect on previous research and plan future research. Furthermore, such an overview helps practitioners understand the state of research, and how research results can help practitioners in their architectural decision-making.MethodWe conducted a systematic mapping study, covering studies published between January 2002 and January 2012. We defined six research questions. We queried six reference databases and obtained an initial result set of 28,895 papers. We followed a search and filtering process that resulted in 144 relevant papers.ResultsAfter classifying the 144 relevant papers for each research question, we found that current research focuses on documenting architectural decisions. We found that only several studies describe architectural decisions from the industry. We identified potential future research topics: domain-specific architectural decisions (such as mobile), achieving specific quality attributes (such as reliability or scalability), uncertainty in decision-making, and group architectural decisions. Regarding empirical evaluations of the papers, around half of the papers use systematic empirical evaluation approaches (such as surveys, or case studies). Still, few papers on architectural decisions use experiments.ConclusionOur study confirms the increasing interest in the topic of architectural decisions. This study helps the community reflect on the past ten years of research on architectural decisions. Researchers are offered a number of promising future research directions, while practitioners learn what existing papers offer.     

Visualising a knowledge mapping of information systems investment evaluation

Information systems (IS) facilitate organisations to increase responsiveness and reduce the costs of their supply chain. This paper seeks to make a contribution through exploring and visualising knowledge mapping from the perspective of IS investment evaluation. The evaluation of IS is regarded as a challenging and complex process, which becomes even more difficult with the increased complexity of IS. The intricacy of IS evaluation, however, is due to numerous interrelated factors (e.g. costs, benefits and risks) that have human or organisational dimensions. With this in mind, there appears to be an increasing need to assess investment decision-making processes, to better understand the often far-reaching implications associated with technology adoption and interrelated knowledge components (KC). Through the identification and extrapolation of key learning issues from the literature and empirical findings, organisations can better improve their business processes and thereby their effectiveness and efficiency, while preventing others from making costly oversights that may not necessarily be only financial. In seeking to enlighten the often obscure evaluation of IS investments, this paper attempts to inductively emphasise the dissemination of knowledge and learning through the application of a fuzzy Expert System (ES) based knowledge mapping technique (i.e. Fuzzy Cognitive Map [FCM]). The rationale for exploring knowledge and IS investment evaluation is that a knowledge map will materialise for others to exploit during their specific technology evaluation. This is realised through conceptualising the explicit and tacit investment drivers. Among the several findings drawn from this research, the key resulting knowledge mapping through FCM demonstrated the complex, multifaceted and emergent behaviour of causal relationships within the knowledge area. The principal relationships and knowledge within IS investment evaluation are illustrated as being determined by a blend of managerial and user perspectives.     

超快平面显微成像技术

快速成像技术在很多领域都有着重要的应用,本文基于超短光脉冲的时-空-频映射原理,提出并实现了一种超快平面显微成像技术。利用色散傅里叶变换及空间色散器件把光脉冲的宽带频谱信息分别映射到时域和空域,利用高速光电探测器进行串行单像素成像,最终获得了帧速率为20.9 MHz,空间分辨率为22 μm和55 μm的一维及二维平面成像系统。在实验中用标准的分辨率目标板验证了成像效果。该技术为超快成像提供了一种有效手段,并将应用于高速平面检测等多个领域。     

A comparison of atomic force microscope friction and phase imaging for the characterization of an immiscible polystyrene/poly(methyl methacrylate) blend film

Three different forms of atomic force microscope (AFM) measurement, topography, friction force and phase imaging, have been used to investigate the surface morphology and local composition of an immiscible polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend film. This sample forms discrete, micron-size domains in a continuous matrix, which is attributed to the segregation of PMMA in PS. When the samples were imaged in air, contrast in friction and phase images was caused by variations in sample topography only. When the samples were imaged under water, however, both friction and phase imaging yielded non-topographic contrast between domains. We ascribe the contrast in both of these imaging modes to preferential softening of the hydrophilic, PMMA-rich domains and to stronger tip-sample adhesive forces, highlighting the AFM's utility for probing local elastic properties and for compositional mapping of soft polymer samples.     

自适应二进制算术编码的动态可重构实现研究

针对H.266/VVC视频编码标准下的上下文自适应二进制算术编码器编码速度慢、资源开销大的问题,面向可重构结构依据算法的内在并行特性优化了编码架构,并基于动态可重构阵列处理器设计实现了CABAC编码器常规编码模式下的并行映射方法,阵列结构能够根据编码输入对优化后的算法进行动态重构,在避免专用硬件编码器较高的资源开销情况下利用软件重构的方法实现熵编码过程,保证编码准确性的同时提高了视频数据流编码效率,为此类运算密集型算法的硬件实现提供了更为灵活高效的参考途径。仿真结果表明,映射实现的编码过程中每个编码周期完成5个二进制序列的编码,平均编码效率达到384.13Mbin/s。基于FPGA的测试结果表明,软件重构方法与专用硬件实现的编码器相比,资源开销降低且编码效率提升5.47%,与同类型可重构视频编码结构相比,编码效率提升7.03%。     

基于APIC的高精度定时器设计

在操作系统开发过程中需要一定精度的计时器支持。在Windows实时扩展改造过程中,针对原有定时精度低和波动较大的问题,提出一种基于高级可编程中断控制器(APIC)的高精度定时器设计方案。利用CPU片上结构APIC的计数寄存器编程,构建高精度时钟。运用内核驱动建立内核调度管理,通过内存映射提高用户态到内核态的数据传输速度,保证实时性能。利用DLL提供一组和内核交互的定时器接口供用户使用。实验结果表明,该方案有效解决了定时精度和稳定性问题,构造的定时器性能稳定,具有良好的实用性。