Studying Formability Limits By Combining Conventional and Incremental Sheet Forming Process

In this work it is assessed the potential of combining conventional and incremental sheet forming processes in a same sheet of metal.This so-called hybrid forming approach is performed through the manufacture of a pre-forming by conventional forming,followed by incremental sheet forming.The main objective is analyzing strain evolution.The pre-forming induced in the conventional forming stage will determine the strain paths,directly influencing the strains produced by the incremental process.To conduct the study,in the conventional processes,strains were imposed in three different ways with distinct true strains.At the incremental stage,the pyramid strategy was adopted with differ-ent wall slopes.From the experiments,the true strains and the final geometries were analyzed.Numerical simulation was also employed for the sake of comparison and correlation with the measured data.It could be observed that single-stretch pre-strain was directly proportional to the maximum incremental strains achieved,whereas samples subjected to biaxial pre-strain influenced the formability according to the degree of pre-strain applied.Pre-strain driven by the prior deep-drawing operation did not result,in this particular geometry,in increased formability.     

An optimization-driven approach for computing geodesic paths on triangle meshes

There are many application scenarios where we need to refine an initial path lying on a surface to be as short as possible. A typical way to solve this problem is to iteratively shorten one segment of the path at a time. As local approaches, they are conceptually simple and easy to implement, but they converge slowly and have poor performance on large scale models. In this paper, we develop an optimization driven approach to improve the performance of computing geodesic paths. We formulate the objective function as the total length and adopt the L-BFGS solver to minimize it. Computational results show that our method converges with super-linear rate, which significantly outperforms the existing methods. Moreover, our method is flexible to handle anisotropic metric, non-uniform density function, as well as additional user-specified constraints, such as coplanar geodesics and equally-spaced geodesic helical curves, which are challenging to the existing local methods.     

矿业企业传统型HR转型路径研究——基于HRBP-COE-SSC模式

在经济新常态以及矿业企业产业转型升级的新环境中,诸多矿业企业尝试进行人力资源变革以增加其价值创造,为企业长远战略发展提供人力资源支持。在对中国矿业企业传统人力资源管理现状进行宏微观分析的基础上,提出基于HRBP-COE-SSC模式的转型路径,并分别从HRBP、COE、SSC模块进行了分析探讨,同时提出了相应的转型建议。     

基于无连接多路径路由的负载均衡

介绍了一种可以应用于Internet网络的无连接多路径路由计算方法,称为概率无连接多路径路由(probability-Disjoint Multi-paths Routing,p-DMR)。该方法使用概率构造无连接多路径,降低了在复杂网络环境中计算无连接多路径的复杂度,并将多路径路由与自适应按比例动态流量分割算法相结合,使网络性能得到优化,拥塞得到避免。     

集成化车间作业计划动态关键路径编制算法

针对单件小批生产加工装配式制造的特点,结合车间作业计划与物料需求计划的集成化管控需求,提出了基于生产过程网络图的动态关键路径作业计划编制算法.算法按照零部件加工装配过程中的工艺顺序和装配关系,将计划期内订单的形成过程抽象化为生产过程网络图,并将物料需求计划映射为网络图中的节点,进行生产能力控制和加工装配约束.以生产过程网络图为作业计划编制的对象模型,以订单的交货期为依据,采用倒排的方式,通过动态寻找网络图中的关键路径来确定车间作业计划顺序和资源分配.通过某密封产品生产企业机加车间生产计划编制的实例,证明了该算法能快速有效地在有限生产能力条件下编制高效可行的车间作业计划,保证作业计划与物料需求计划的一致性.     

行星轮系动力学新模型及其故障响应特性研究

行星轮系中零部件多、结构复杂,建模难度大。行星轮既自转又公转,导致啮合点到固定在箱体上的传感器之间的距离时刻变化,从而产生振动传递路径时变效应,增加了振动响应的复杂性。现有的动力学模型大多针对正常情况下的行星轮系进行建模,而且未考虑振动传递路径时变效应对振动响应的影响。针对以上不足,推导了行星轮系正常、裂纹及剥落三种情况下的时变啮合刚度算法,考虑振动传递路径时变效应的影响,建立了相应的动力学模型,求解得到行星轮系正常、裂纹及剥落时的动态响应,并分析了它们的频谱特性。搭建了行星齿轮箱试验台以获取振动响应信号,与模型响应信号进行了对比分析,结果验证了动力学模型的准确性,为行星轮系的健康监测提供了理论依据。     

考虑潜在起点的RP路径排序问题研究

充分考虑路径排序问题的一般性,建立了快速成形中扫描填充加工路径排序优化问题的两种完整数学计算模型,提出并证明了路径的遍历策略及简化定理。引入路径潜在起点的概念,设计了基于所有路径潜在起点（而非仅仅原始起点）的全局贪婪搜索求解算法。该算法不仅适用于所有路径排序问题,而且因为扩大了搜索范围,避免了一般贪婪算法对路径内节点初始排列次序的依赖性,求出了路径排序问题的全局更优解。     

The effects of reduction of the deposited waste on short‐term landfill leachate composition of a landfill: a case study in Norway

Municipal solid waste landfill leachate was sampled over from a landfill receiving varying amounts of municipal solid waste. The investigation aimed to provide information on expected leachate changes in the short term, either after closure of an active landfill, or after a strong decline in the amount of waste deposited at smaller landfills. It was found that during a two year period following a sudden decline in the amount of waste deposited, the levels of various chemical and physical parameters all dropped sharply. The reasons for the decline in discharge levels are thought to be aerobic decomposition taking place in the municipal solid waste just after landfilling, and thus the decline in the impact of this process when there were less fresh waste masses available, and formation of preferential flow paths for the leachate as the municipal solid waste stabilized in the landfill.     

饱和重塑黄土的动力特性

基于饱和重塑黄土的静、动力三轴试验结果,探讨了饱和重塑黄土的静、动力特性。分析了静力试验中饱和重塑黄土的应力-应变关系。根据动力试验结果研究了饱和重塑黄土轴向应变、动强度、有效应力路径和滞回圈的变化规律:轴向应变随着振动次数的增加逐渐增大,且变化曲线存在着明显转折点,在较低围压时,εa分为先平缓上升和后陡升至破坏两个阶段,在较高围压时,εa分为振动初期存在陡升然后平缓上升最后又陡升至破坏三个阶段。有效应力路径逐渐向左发展,且移动幅度逐渐加大。每一个振次的有效应力路径形成一个封闭的区域,试验过程中封闭区域的面积逐渐增大。随着振动次数逐渐增大,滞回圈的面积和倾斜度均逐渐增大。通过动弹模试验结果发现饱和重塑黄土在不同围压下1/Ed均随着εa的增大而增大,确定出不同围压下1/Ed~εa关系中的a、b值和最大动弹模Edmax;阻尼比λ随动应变εa的增大逐渐增大,且最终趋于稳定,给出不同围压下阻尼比λ的建议值,从而为指导工程实践提供参考。     

低渗透厚油层层内优势窜流通道定量识别新方法研究

针对低渗透厚油层引入能有效表征优势窜流通道的4项参数,应用加权K-means聚类算法开展优势窜流通道的定量识别方法研究。利用该方法对乾安油田Ⅰ区Ⅶ砂组油藏59口井177小层进行识别,诊断出22口井存在优势窜流通道,与研究区示踪剂检测结果基本相符。根据优势窜流通道的单井识别结果,绘制了优势窜流通道平面分布图,研究其分布规律。优势窜流通道的分布区域主要受砂体微相、砂体形态及古水流方向的控制。