可控拉深筋对高强度板盒形件拉深性能的影响

应用模拟仿真技术,结合正交实验设计方法,通过6种不同形状的拉深筋和3种不同的拉深筋运动轨迹的高强度板盒形件的拉深成形模拟仿真,研究了可控拉深筋对高强度板盒形件拉深性能的影响。以极限拉深深度为评价指标,分析结果数据,得到轨迹二拉深筋上升—静止—下降为最优运动轨迹,并且3种可控拉深筋运动轨迹的指标均比固定拉深筋的大,证明可控拉深筋能够改善高强度板的成形性能。其中直球头拉深筋的改善效果比斜球头显著,但斜球头比直球头具有更好的极限拉深高度,并通过极差分析得到其主要影响因子为拉深筋前后的高度。最后通过成形力分析,解     

电场计算的快速多极子预条件高阶边界元法

针对多介质工频电场计算中低阶边界元法及预条件(GMRES)法的计算精度低及计算成本高的不足,在低阶边界元法基础上引入高阶边界元和快速多极子法,提出了一种用于求解三维电场分布的快速多极子预条件GMRES高阶边界元法。建立了三维电场计算高阶边界元模型,阐述了快速多极子预条件GMRES高阶边界元法基本原理和具体实现方法;通过双介质实验模型进行了方法验证,并基于500kV变电站部分关键设备的三维电场计算,表明该方法在电场计算精度及在内存消耗和计算时间上均比预条件GMRES法有明显的优势。最后将计算结果与实际测量值进行了比较,该方法的计算结果与测量值最大相对误差为8.65%,该方法更适合于分析变电站这种大尺度多介质环境下的工频电场分布。     

Surface latent heat flux anomalies before the <Emphasis Type="Italic">M</Emphasis><Subscript>S</Subscript> 7.1 New Zealand earthquake 2010

By analyzing surface latent heat flux (SLHF) data from the NCEP/NCAR Reanalysis Project for the period three months before and after the Sept. 3, 2010 M S 7.1 New Zealand earthquake, an isolated SLHF positive anomaly on Aug. 1, 2010 was found with a high value of about 160 W/m 2 to the northeast of the epicenter. Historical data, background pixels, and wavelet transforms of time series were comprehensively analyzed to study the spatiotemporal features of the SLHF anomaly. After removing the influences of wi...     

β-Ca2P2O7/CaSO4陶瓷的制备和体外降解研究

将β-焦磷酸钙和无水硫酸钙2种粉体进行复合,制备出β-焦磷酸钙/无水硫酸钙(β-Ca2 P2O7/CaSO4)复相生物陶瓷.研究了β-Ca2 P2 O7和CaSO4的比例和烧结温度对复相陶瓷气孔率、体积密度和相组成的影响,结果表明:随着CaSO4含量的增加,复相生物陶瓷的气孔率升高,体积密度降低;随着烧结温度的升高,复...     

利用表面纳米化技术改善AZ31镁合金的弯曲性能

镁合金因为其低密度和高比强度,成为新一代的结构材料。对比钢铁和铝合金,镁合金板材的弯曲成型性能相对较差。对于如何提高其成型性能成为了近年来的研究重点。表面纳米化是一种有效提高镁合金强度和表面硬度的手段,然后镁合金在表面纳米化之后,其塑性会明显降低,从而影响成型性能。 本文通过超声喷丸的方式,在镁合金的表面制备了不同厚度（51–145 μm）的纳米层,研究了表面纳米化之后的AZ31镁合金板材的V型弯曲性能。通过研究发现,双面纳米化处理的镁合金表现出和未处理相近的弯曲性能。同时,单面处理的板材表现出优于未处理板材的弯曲性能。当纳米层在弯曲过程中位于单侧处理的板材的内测,其改变了板材中性层在弯曲过程中的外移趋势,从而提高了弯曲性能,研究表明这种提高是非常有限的。在超声喷丸5 min处理的板材中,其中性层偏移最少,更厚的纳米层使得中性层偏至板材内测,从而降低弯曲性能。当纳米层在弯曲过程中位于板材的外层时,板材的弯曲性能也得以提高并且提高程度随着纳米层厚度的增加而增加。这是因为纳米材料在弯曲过程中导致了应力应变的再分布。在板材外层增加纳米层后,其弯曲顶端得到了应力更大应变更小的一种分布情况,而这种分布有利于纳米化后的板材的弯曲,从而阻止了裂纹的产生,提高了弯曲性能。     

Technology and the Body: the (Im)Possibilities of Re-embodiment

This article argues for a more rigorous distinction between body extensions on the one hand and incorporation of non-bodily objects into the body on the other hand. Real re-embodiment would be a matter of taking things (most often technologies) into the body, i.e. of incorporation of non-bodily items into the body. This, however, is a difficult process often limited by a number of conditions of possibility that are absent in the case of ??mere?? body extensions. Three categories are discussed: limb extensions/prostheses, perceptual extensions/prostheses and cognitive extensions/prostheses. For each category, a distinction between extensions and incorporations is proposed, and the conditions of possibility for real incorporation are discussed. These conditions of possibility differ in each category, but in general they ask for radical or fundamental alterations not only in the motor and/or sensory or cognitive constitution of a human subject, but also in his or her subjective experience.     

A Computational Model of the Belief System Under the Scope of Social Communication

This paper presents an approach to the belief system based on a computational framework in three levels: first, the logic level with the definition of binary local rules, second, the arithmetic level with the definition of recursive functions and finally the behavioural level with the definition of a recursive construction pattern. Social communication is achieved when different beliefs are expressed, modified, propagated and shared through social nets. This approach is useful to mimic the belief system because the defined functions provide different ways to process the same incoming information as well as a means to propagate it. Our model also provides a means to cross different beliefs so, any incoming information can be processed many times by the same or different functions as it occurs is social nets.     

一种基于量子化状态系统的刚性ODE求解方法

量子化状态系统(Quantized State System,QSS)在求解一般常微分方程(Ordinary Differential Equation,ODE)系统时,比传统基于时间离散的积分方法更具优势,但QSS方法不适合求解刚性ODE系统,为此提出一种基于量子化状态系统的步进校正优化算法(Step-correction Optimization Algorithm Based on QSS,SCOA based-on QSS),它结合QSS方法及隐式算法中梯形积分法的思想,以有效提高刚性ODE系统的求解精度和效率。通过对3个典型刚性ODE算例的仿真求解,结果表明,SCOA based-on QSS算法总体上比其他算法更具优势,同时在适当减小量子大小时能显著提高仿真精度。     

城市建成环境对公共自行车使用的影响机制研究 ——以深圳市南山区为例

以深圳市南山区363个公共自行车站点的自行车使用频次及周边500 m缓冲区建成环境为研究对象, 采用空间滞后模型, 在考虑公共自行车站点区位、公共交通设施环境、自行车骑行环境和相邻站点空间自相关的基础上, 重点研究反映不同人群集聚的土地利用类型对各站点公共自行车使用频次的影响。结果表明, 工作日高峰、周边公交线路数量、周边道路用地面积、支路长度、周边工业建筑面积、低档商服建筑面积和低档住房建筑面积对公共自行车使用频次具有显著正向影响, 到最近地铁站距离和绿道长度对公共自行车使用频次具有显著负向影响, 站点间公共自行车流量具有高度空间自相关性。建议规划公共自行车站点时应重点关注周边建成环境因素, 在布点和定价时充分考虑通勤等规律性需求, 并结合人口分布特点, 增加低收入人群集聚区的供给量。