肢体残疾者作业能力差损模型及应用

针对肢体残疾者工作安置及调适,提出一个肢体残疾者作业能力差损模型。建立肢体残疾者作业分析的基本动素库,用肌肉骨骼特征值及耐力两类参数描述,将作业要求映射到动素的生物力学参数集上,并以此建立肢体残疾者作业能力动态层次评价体系,测算作业要求与作业能力的差值。引入作业能力基准面凹陷率的概念,从单个动素的作业空间、作业工具、总体作业目标等多层面刻画肢体残疾者作业能力与作业要求的差距,并用实例验证模型的实效性。     

标准化作业的价值分析

本文创建了自然态劳动作业模型,对自然态劳动作业模型的特点进行了分析,创建了标准化的劳动作业模型,对标准化劳动作业模型的特点作了深入的分析,建立了工业生产的机群模型和流水模型,并进行了对比分析,对自然态劳动作业模型和标准化作业模型进行了对比分析,讨论了标准化作业的价值作用和效果。     

基于TOC的业务外包决策模型研究

建立了业务外包决策问题的数学模型,阐述了标准约束理论下业务外包决策过程,指出了多瓶颈情形下标准TOC方法的不足,提出了集成作业成本法的改进模型,较好地解决了多瓶颈问题,分析了新模型制定短期决策和长期决策的侧重点.实践证明,新模型制定的业务外包决策比标准TOC方法模型更合理有效,企业获取的利润更大.     

VDT作业视觉环境质量的评价方法

从照度、亮度、眩光、视屏显示质量、光色等方面设计了评价VDT作业视觉环境的指标体系。建立了VDT作业视觉环境质量的综合评价模型，并利用该模型对某些企业VDT作业场所的视觉环境进行了评价。应用实例的结果表明，本文建立的模型能够对VDT作业场所的视觉环境做出正确的评价。     

基于作业成本法的一个库存成本控制模型

作业成本法在物流系统中运行,将可以更好地帮助决策者进行物流决策.论文通过对传统库存模型分析,基于作业成本原理深入分析了库存系统中补货、库存持有和缺货作业的成本动因,并根据这些成本动因建立了基于作业成本法的库存模型来改进传统库存模型,同时数值算例分析与比较也被提供来分析作业成本法对传统库存模型的影响.研究结果显示基于作业成本法的库存模型比传统库存模型在成本控制方面更有效,如果采用传统库存模型可能导致决策错误.     

造船厂钢板出库作业计划的建模及优化研究

对于造船厂钢板堆场出库作业计划问题,在分析堆场出库作业流程的基础上,建立了以出库作业时间最短为目标的优化模型.该模型可归结为多层组合优化问题.针对本问题寻优过程的阶段性和复杂性的特点,提出了基于改进遗传算法的多层嵌套启发式优化算法.与传统人工决策的作业方案相比,该优化结果可以缩短24%～67%的作业时间.     

基于作业成本核算体系的产品组合决策

在现代制造环境下,传统的成本核算法不能准确地计算出产品的成本,利用作业成本法的思想建立在制造型企业内产品成本的计算软件,并在这个基础上对多品种小批量的企业的产品组合进行决策。     

订货生产式企业作业任务交货期决策研究

分析了工序时间的随机性特征及其对任务完工期的影响及作业任务交货期决策的重要性，确定任务交货期的方式，指出在工序时间随机性特征条件下，任务交货期应为一个区间，建立了以损失费用最小化为目标的最优交货期时区模型、最优最早交货期模型、最优完工时间偏差控制模型，采用计算机迭代法验证了上述各模型的有效性。     

生产作业中工序要素和操作人员的有效组合

通过建立效益最大化模型,对标准化作业中的工序要素和操作人员进行有效组合,并以S汽车制造厂油漆车间生产线实施标准化作业为实例,对该模型实施过程及有效性进行验证.实例证明,该模型在生产线的工序要素组合与操作人员的组合优化中可以起到快捷有效的作用.     

面向生产调度评估的ABC成本计算模型

为了有效评估调度方案的经济性,提出了一种改进的作业成本计算模型.从ERP的角度对制造资源进行了分类,建立了基于价值链的作业模型,提出了三阶段作业成本计算模型,并对模型的求解过程进行了详细阐述.通过一个案例,分别采用传统成本法和新提出方法计算产品生产成本,并对结果进行了对比分析,证明提出的新方法可以有效地评估调度质量.     

Use of a trapping agent for simultaneous capturing and high-throughput screening of both "soft" and "hard" reactive metabolites

Glutathione (GSH) has been widely used for in vitro trapping and subsequently detecting reactive metabolites using liquid chromatography-mass spectrometry. A major drawback of GSH is its low trapping efficiency for "hard" reactive metabolites such as reactive aldehydes. In the present study, a bifunctional trapping agent (gamma GSK, gamma-glutamylcysteinlysine) is investigated as an alternative of GSH for simultaneous trapping both "hard" and "soft" reactive metabolites. In microsomal incubations, soft and hard reactive metabolites are captured by conjugation to the free thiol and the amine group of gamma GSK, respectively, resulting in formation of stable peptide adducts. Similar to GSH conjugates, all gamma GSK adducts derived from both soft and hard reactive metabolites contain a gamma-glutamyl moiety and, thus, undergo a neutral loss of 129 Da under collision-induced dissociation. As a result, an NL MS/MS scan can be utilized as a generic method for rapid detecting of both hard or soft reactive metabolites. As demonstrated by a number of model compounds, this approach, in combination with the isotope trapping technique, is reliable, sensitive, and efficient and can be potentially utilized as a high-throughput method for screening and rapid identification of both soft and hard reactive metabolites. In comparison with other methods, this approach is highly efficient and suitable in drug discovery for screening a wide variety of compounds for different reactive metabolites.     

Reliability modeling for multistage systems subject to competing failure processes

In this paper, a novel multistage reliability model is provided as systems are often divided into many stages according to system degradation characteristics. Multistage hard failure (caused by random shock) process (MHFP) and multistage soft failure (caused by random shock and continuous degradation) process (MSFP) are introduced to describe the competing failure processes, where either the MSFP or MHFP would break down the system. The shock processes impact the system in three ways: (1) fatal load shocks cause hard failure immediately in the hard failure process; (2) time shocks cause a hard failure threshold changing; (3) damage load shocks cause degradation level increasing in the soft failure process. In this paper, a density function dispersion method is carried out to address the multistage reliability model, and the effectiveness of the proposed models is demonstrated by reliability analysis with the one-stage model. Finally, the multistage model is applied to a case study, the degradation process is divided into three stages, and the hard failure threshold can be transmitted twice. The proposed model can be applied in other multistage situations, and the calculation method can satisfy the accuracy requirements.     

Effects of Material Properties on Granular Flow in a Silo Using DEM Simulation

In order to test the effect of material properties on flowability of particulate materials, discharge procedures of spherical particles within a flat-bottomed model silo with three sets of material properties, i.e., soft and hard without adhesion and adhesive hard, were simulated using the Discrete Element Method. For each system, three particles on the center line were selected and their instant vertical velocity components were traced. In addition, both discharge and the rate were recorded throughout the procedure. The predicted results show that, for both the systems without adhesion, though the soft has a material modulus only 1/1000 of the hard, there are no significant differences in f low pattern and discharge rate. This suggests that a soft system can be used to predict the behavior of a hard one to save CPU time in a gravity-driven granular flow. On the other hand, comparison between both hard systems shows that adhesion can significantly reduce the flowability in granular flow. By analyzing the velocity plot for the traced particles, free fall was clearly detected above the decompression zone, indicating the motion of a particle in a granular flow can be resolved as free fall together with the movement due to particle collision. In addition, select dynamic behavior related to the kinetic fluctuations affecting flow was observed. discrete element method silo granule flow particulate material     

Effects of Material Properties on Granular Flow in a Silo Using DEM Simulation

In order to test the effect of material properties on flowability of particulate materials, discharge procedures of spherical particles within a flat-bottomed model silo with three sets of material properties, i.e., soft and hard without adhesion and adhesive hard, were simulated using the Discrete Element Method. For each system, three particles on the center line were selected and their instant vertical velocity components were traced. In addition, both discharge and the rate were recorded throughout the procedure. The predicted results show that, for both the systems without adhesion, though the soft has a material modulus only 1/1000 of the hard, there are no significant differences in f low pattern and discharge rate. This suggests that a soft system can be used to predict the behavior of a hard one to save CPU time in a gravity-driven granular flow. On the other hand, comparison between both hard systems shows that adhesion can significantly reduce the flowability in granular flow. By analyzing the velocity plot for the traced particles, free fall was clearly detected above the decompression zone, indicating the motion of a particle in a granular flow can be resolved as free fall together with the movement due to particle collision. In addition, select dynamic behavior related to the kinetic fluctuations affecting flow was observed.

discrete element method silo granule flow particulate material     

Modelling of soft and hard surfaces using ideal perfect electric conducting/perfect magnetic conducting strip grids

Strip-loaded surfaces and corrugated surfaces can be efficiently analysed using asymptotic boundary conditions that are valid in the limit of vanishing strip and corrugation period, respectively. An even simpler boundary condition is obtained by assuming that the surfaces are ideally soft or hard. This corresponds to a curvilinear grid of quasi-parallel perfect electric conducting (PEC) and perfect magnetic conducting (PMC) strips of incremental width and period, referred to as a PEC/PMC strip grid. Such a simple model for soft/ hard surfaces speeds up the design process and provides the proper object parameters under the ideal soft or hard conditions. After reaching the designed characteristics, one can study the bandwidth of realisations of the surface using the asymptotic boundary conditions and finally make a complete and detailed study of all characteristics of the realisations by including even the finite period of the strips and corrugations. The ideal PEC/PMC strip model is used here as an example applied to bodies of revolution (BOR) such as soft horns with transverse corrugations and hard horns with longitudinal corrugations. The longitudinally corrugated horn is not a BOR, but both the asymptotic boundary condition and the ideal PEC/PMC strip model make it possible to analyse it as a BOR with an anisotropic wall and this reduces the computer time enormously compared to a full wave analysis for a finite corrugation period. It is shown that the PEC/PMC strip grid can predict the radiation patterns well at the centre frequency, but the bandwidth cannot be determined.     

单输入多输出耦合设计任务二阶段迭代模型研究

产品开发过程中单输入多输出耦合设计任务间存在复杂的信息依赖关系。采用单阶段方法的任务执行方式时,因所执行的任务数量多并且需传递的信息量大,致使任务间存在的复杂信息关系难以被理清,从而导致任务执行过程中的方案分配不够合理,任务间的迭代返工次数过多,产品开发周期过长。针对这些问题,在深入分析单输入多输出耦合设计任务单阶段迭代模型的基础上,提出了一种任务迭代过程中的信息处理策略,并构建了一种单输入多输出耦合设计任务的二阶段迭代模型及其求解执行时间的数学模型。应用该数学模型,可以计算得到最佳二阶段设计任务分配方案。以某发动机开发项目为例,进行了该方法的应用分析。研究表明,采取二阶段迭代模型,任务迭代执行时间比单阶段短,并且通过合理分配在1,2两个阶段执行的任务,能够获得最短的二阶段任务迭代执行时间。该方法根据任务间不同的信息关系选择合适的任务迭代模型,能够有效缩短产品开发周期,可为产品设计人员在产品开发过程中选择合理的任务执行方式提供一定的理论参考。     

Research on a two-stage iterative model of coupling design task with single input and multiple output北大核心CSCD

In the process of product development, there is a complex information-dependent relation between coupling design tasks with single input and multiple output. Because of the large amount of executed tasks and transmitted information, the complicated relationship between these tasks is hard to be sorted out by using the single-stage task execution method, which may lead to problems such as the unreasonable allocation of tasks in the process of task execution, excessive iteration rework times between tasks and too long product development cycle. To solve these problems, an information processing strategy for the task iteration was put forward, and a two-stage iteration model and the mathematical model of calculating task execution time were built based on the deep analysis of a single-stage iteration model for the coupling design task with single input and multiple output. The best two-stage task allocation scheme was obtained by working out this mathematical model. The effectiveness of this method was proved through the example of an engine development project. The results showed that the iterative execution time of tasks was shorter than single-stage by using the two-stage iteration model and the shortest iterative execution time of the two-stage iteration model could be obtained by reasonably assigning tasks into two phases. The method selects the appropriate task iterative model according to the different information relations between tasks, which can effectively shorten the product development cycle and provide some theoretical reference for product designers to choose reasonable task execution way in the process of product development.     

线接触作用下超薄膜-基底界面力学分析

高副接触的摩擦部件中广泛使用1 μm左右的超薄膜,其界面失效对部件的工作寿命具有重要影响。该文针对轴承钢基底表面1 μm厚度的硬质和软质超薄膜所构成的膜基系统,建立了线接触载荷作用下的界面力学分析模型。采用复变函数镜像法求解了单元点力的格林函数解,并积分获得了界面应力的分布状态。利用匀质模型完成了退化对比验证,以DLC和MoS₂两种硬软固体薄膜的线接触为例进行了计算和分析。该方法可用于机械部件表面沉积超薄膜的膜基界面分析与设计。     

Combination hysteresis model for accommodation magnetization

We describe an accommodation hysteresis model based on a combination of history-dependent and history-independent models. The amount of accommodation is changed by varying the weights of the models employed in the resulting model. We illustrate the operation of the proposed model with accommodating cycles attached to the major loop. The model can be useful in further investigations of the accommodation phenomenon, as we show by using complex trajectories constructed by it. It can be incorporated in magnetodynamic calculations and circuit analysis.     

Numerical investigation of structural crash response of thin-walled structures on soft soil

Accident statistics show that although the certification of aircraft structures is based on crash scenarios on hard or rigid surfaces, in reality most of the crash cases occur on soft soil or water. Therefore a structure which is designed for hard surfaces may not be safe enough for a possible crash scenario on water or soft soil. Finite element method (FEM) has been used in several numerical investigations and promising results were obtained. However, since soil is a granular medium this work aims at numerical modeling of the experimentally observed soil behavior using particle-based numerical technique. In this work numerical simulations of the crash tests on idealized cones and hemispheres were used to validate the models and compare FEM-based models with particle-based models. The results of numerical simulations were compared with quasi-static and dynamic test results conducted on coarse sand sample at the Deutsches Zentrum fur Luft- und Raumfahrt e.V (DLR). After obtaining a stable and accurate particle-based numerical model for the soft soil the crash performance of deformable metallic energy absorbers on soft soil ground was investigated and compared with test data and numerical investigations of rigid ground impacts.