折臂式随车起重机转台的拓扑优化设计

为了使折臂式随车起重机转台在最大应力不超过材料许用应力的前提下实现轻量化设计的目的,通过ADAMS软件仿真确定其极限工况,对转台进行静力学分析及拓扑优化。通过拓扑优化得到了理想的材料分布。基于优化结果调整转台结构,并对改进后的转台进行静力学分析。结果表明,优化后的转台能够满足实际的使用需求。同时,转台质量降低了12%,证明了优化设计的有效性和可行性,并为折臂式随车起重机的相关设计提供了一定的借鉴。     

大规模多状态计算系统的容错性能分析

针对异构计算节点组成的大规模多状态计算系统的容错性能分析问题，提出了一种计算系统容错性能的评估方法。该方法采用自定义的两级容错性能形式化描述框架进行系统描述，通过构造多值决策图（Multi-value Decision Diagram，MDD）模型对系统进行容错性能建模，并基于构造的模型高效地计算出部件故障的条件下计算系统在特定性能水平上运行的概率，减少了计算的冗余性。实验结果表明，该方法在模型的大小和构建时间上均优于传统方法。该方法的提出将对系统操作员或程序设计者具有重要意义，使其确保系统适合预期应用。     

喷淋液滴在空气环境下的运动特性

本文以喷淋液滴在空气环境下运动特性为工程背景，建立单个液滴在常温、常压空气环境中的动量方程，分析液滴沉降特性、追赶特性及运动轨迹行为。计算结果表明，不同喷淋液滴初始条件下，短时间内存在重力大于曳力和重力小于曳力两种情况，但最终减速液滴均会达到受力平衡状态；液滴离开喷淋头后，垂向位移均迅速增大，液滴粒径越大、初始速度越大，垂向位移增长的速率也越大，达到相同位移的用时越短；液滴尺寸、初始速度相差越大，液滴追赶所用的时间越短，追赶位移越小，液滴尺寸、初始速度越接近，液滴追赶所用的时间越长，追赶位移越大；液滴初始速度越大、初始直径越大、喷射角度越大，横向速度消失越慢，达到的横向位移越大，喷射液滴覆盖的面积也越大。计算结果有助于优化工程实际中喷淋系统的设计与布置。     

Nonlinear dynamic behaviors and control based on simulation of high-purity heat integrated air separation column

In this paper, the dynamic behaviors on the basis of simulation for high-purity heat integrated air separation column (HIASC) are studied. A nonlinear generic model control (GMC) scheme is proposed based on the nonlinear behavior analyses of a HIASC process, and an adaptive generic model control (AGMC) scheme is further presented to correct the model parameters online. Related internal model control (IMC) scheme and multi-loop PID (M-PID) scheme are also developed as the comparative base. The comparative researches are carried out among these linear and nonlinear control schemes in detail. The simulation research results show that the proposed AGMC schemes present advantages in both servo control and regulatory control for the high-purity HIASC.     

R-curves determination of ordinary refractory ceramics assisted by digital image correlation method

As a figure-of-merit, the rising ratio of crack propagation resistance to fracture initiation resistance indicates a reduction of the brittleness and enhances the thermal shock resistance of ordinary refractory ceramics. The significant nonlinear fracture behaviour is related to the development of a fracture process zone (FPZ). The universal dimensionless load–displacement diagram method is applied as a promising graphical method for the determination of R-curves for magnesia refractories showing different brittleness. By applying digital image correlation (DIC) together with the graphical method, the problems arisen with accurate determination of the fracture initiation resistance and the crack length are overcome. Meanwhile, the R-curve is subdivided with respect to the fracture processes, viz the fracture initiation, the development of FPZ and the onset of traction free macro-crack. With the simultaneous crack lengths evaluated from DIC, the contribution of each fracture process to the crack propagation resistance at certain loading stage is quantitatively presented.     

基于GIS单线图的配网停电单模拟操作应用研究

配电网停电会造成电力系统供配电可靠性以及服务质量下降,研究基于地理信息系统(GIS)单线图的配网停电单模拟操作应用。利用网格长度作为基本单位建立坐标系,以选取起始点与终止点为基础,通过四参数法将GIS坐标映射至图纸网格内,实现配网内设备初步布局,将杆塔、站房和整体均匀分布作为优化目标,设置多目标优化目标函数实现GIS单线图最终优化。选取某电力公司配网作为单模拟操作应用对象,模拟结果表明,单模拟操作配网停电后,该配网各负荷点年故障率、次平均停电时间以及年停电时间均有所减少,可有效提升配网的供配电可靠性。     

Revisiting the Parallel Strategy for DOACROSS Loops

Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front...     

Mixture ratio modeling of dynamic systems

Any knowledge extraction relies (possibly implicitly) on a hypothesis about the modelled-data dependence. The extracted knowledge ultimately serves to a decision-making (DM). DM always faces uncertainty and this makes probabilistic modelling adequate. The inspected black-box modeling deals with “universal” approximators of the relevant probabilistic model. Finite mixtures with components in the exponential family are often exploited. Their attractiveness stems from their flexibility, the cluster interpretability of components and the existence of algorithms for processing high-dimensional data streams. They are even used in dynamic cases with mutually dependent data records while regression and auto-regression mixture components serve to the dependence modeling. These dynamic models, however, mostly assume data-independent component weights, that is, memoryless transitions between dynamic mixture components. Such mixtures are not universal approximators of dynamic probabilistic models. Formally, this follows from the fact that the set of finite probabilistic mixtures is not closed with respect to the conditioning, which is the key estimation and predictive operation. The paper overcomes this drawback by using ratios of finite mixtures as universally approximating dynamic parametric models. The paper motivates them, elaborates their approximate Bayesian recursive estimation and reveals their application potential.     

超分子作用阻尼材料的动态力学模型修正

为提高飞机起落架载荷实测精度，以支柱式起落架结构为研究对象，探讨处理其载荷标定数据的工程方法。首先，对实际受载情况和单向加载工况标定数据的分析，挖掘出三向载荷、缓冲支柱压缩行程与应变码值间的数学关系，将预测的数学关系代入到多向工况的标定数据中，验证了它们的准确性;其次，根据两种标定数据回归方法，提出了对应使用的支柱式起落架载荷-应变标定方程的数学模型;最后，将两种标定方程代回到标定数据中，计算起落架三向载荷，所有反算载荷的误差均在可控范围内，表明标定方程满足精度要求。将标定方程代入实测数据中，实测曲线符合变化规律。该处理方法的应用能有力提高支柱式起落架的起飞-着陆载荷实测和载荷谱编制的准确度。