气相爆轰波在障碍物上Mach反射后流场的分析

详细分析了气相爆轰波在斜劈上Mach反射后的流场。根据胞格结构的烟迹记录，得到了爆轰波Mach反射时三波点迹线与楔面的夹角X与楔角θ的定量关系，依此推算出爆轰波绕射楔块 时从规则反射向Mach反射转变的临界角范围。论文也分析了影响X角和Mach杆后压力的主要 因素。该结果有助于更深入了解爆轰波的本质，也为数值模拟气相爆轰波在障碍物上Mach反射现象提供了可靠的对照依据

不同攻角下超声速降落伞伞绳的影响研究

文章基于一种简易＂浸入边界技术＂与流固耦合方法对超声速来流条件下的三维降落伞系统进行了数值模拟。研究中,降落伞系统包括前体和伞体,两者通过伞绳连接。文章的研究目的是分析不同攻角下降落伞伞绳对于降落伞系统周围复杂非定常流场的影响,以及对降落伞性能表现的影响。结果表明：在较小的前体和伞体距离下,由于攻角的影响,非定常流场结构呈现上下不对称,并且上下伞绳激波形成时间不同步。随着攻角的增加,上下面的伞绳激波形成时间出现推迟,并且有变弱的趋势。另外,由于攻角与伞绳的综合影响,伞内表面的时间平均压力分布在5o攻角时最小,而在10o攻角时最大,阻力系数却随着攻角的增加而增加

超高速冲击铝双层板的熔化效应

对超高速冲击铝双层板的熔化效应,进行了实验研究和数值模拟,用扫描电镜观察后板的弹坑发现:当弹丸碰撞速度超过5km/s时,后板出现熔坑;随着弹丸碰撞速度的增加,后板熔坑数目亦随之增加,碎片云对后板的破坏明显减弱.数值模拟表明,击波加热和塑性功加热是熔化的两种机制,有关熔化主要特征的数值拟结果与实验结果基本吻合

A CE/SE Scheme for Flows in Porous Media and Its Applications

In this paper, a new computational scheme for solving flows in porous media was proposed. The scheme was based on an improved CE/SE method (the space-time Conservation Element and Solution Element method). We described porous flows by adopting DFB (Brinkman-Forchheimer extended Darcy) equation. The comparison between our computational results and Ghia's confirmed the high accuracy, resolution, and efficiency of our CE/SE scheme. The proposed first-order CE/SE scheme is a new reliable way for numerical simulations of flows in porous media. After investigation of effects of Darcy number on porous flow, it shows that Darcy number has dominant influence on porous flow for the Reynolds number and porosity considered

Subgradient integrated into particle swarm optimizer for global optimization

为优化不可微且非凸的连续目标函数,提出了结合次梯度的粒子群全局优化算法(SgPSO)。在优化算法中,首次提出利用次梯度方向来更新粒子群算法中粒子的搜索速度方案。加上与粒子相互间的通信机制配合,改进方案提高了寻得全局最优的机率。进一步地,在次梯度迭代过程中,提出其中的步长函数需要满足关于次梯度幅值是低阶无穷小且关于迭代时刻是递减的充分条件保证序列稳定收敛。最后,针对标准库给出了SgPSO的实验和比较以验证其有效性,结果表明提出的算法能很好地实现目标函数的全局优化,且收敛效果更好。This paper proposed an approach of subgradient integrated into particle swarm optimizer( SGPSO) for globally optimizing continuous objective function.In minimization,it proposed a revision for the manner of velocity update with the direction of subgradient to search for the local minima of a given non-differentiable and non-convex objective function.Thus,it combined with communications among particles,this revision would offer more chances to obtain the global minima.Furthermore,in the part of subgradient iteration,it suggested that the step function should be a lower order infinitesimal with respect to subgradient magnitude as well as be a decreasing function with respect to iteration time.In the end,experiments and comparisons of the proposed SGPSO on benchmark problems validate its performance with better effectiveness and efficiency.国家自然科学基金资助项目(61103121); 广东省自然科学基金资助项目(S2012010008881;S2013010016601

Zernike多项式展开系数的时间相关性

分析了受大气湍流扰动的光波波前在系统接收孔径上的Zernike多项式展开系数的时间相关性,在此基础上进一步分析了从不同方向到达系统接收孔径的光波波前整体倾斜之间的相关性，并给出了光波在水平均匀大气中传播时的结果

Flow state analysis on abrasive motion of centrifugal grinding under different working conditions

The flowing behavior on abrasive grains was analyzed by two-phase flow dynamic model when using different duty parameter in planetary lapping. The results show that the duty parameter will affect and control grains flowing behavior in lapping process. Further, it is pointed out that duty parameter is important to enhance productivity. The parameters of design and technology can be optimized economically and efficiently with the method so as to improve working quality

自适应光学对大气扰动波前的补偿效果研究：II.水平大气传输时…

讨论了光波在水平大气湍流中传输时的情况。计算结果表明自适应光学系统的补偿效果与光波传播路径上的横向风有很大的关系。大气湍流的强度越大, 自适应光学系统的截止频率越高, 横向风的影响也越大。计算结果还表明在相同的r0 或者相同的大气湍流强度下, 球面波所受大气扰动的自适应光学补偿效果受横向风的影响要比平面波的厉害。本文还将理论分析的结果和数值模拟的结果进行了比较, 表明数值模拟结果受横向风的影响比理论分析结果受横向风的影响大。最后, 文中分析了以上现象并对此作出了合理的解释

Numerical simulation of immiscible two-phase flow in T-shaped microchannel

采用摄动有限体积(PFV)算法和水平集(level set)技术对T形微通道内互不相溶两相流动进行了数值模拟研究。考察了两相界面张力和微通道壁面润湿性对流动的影响,精确地捕捉到了油水两相流动的界面。对一些典型的T形微通道油水两相流动进行了数值计算,模拟结果和实验结果吻合较好。分析总结出了微通道内两相流动过程中的一些基本规律,为微通道内的液液两相流动实验设计和工业应用提供了新的数值预测手段

Study on organochlorine pesticide and PCBs at surface water in Xiamen Harbour

利用GC -ECD对厦门西港 1998年 7月取得的 9个站位表层水体中的 18种有机氯农药 (HCHs ,DDTs等 )和 12种多氯联苯 (PCBs)进行分析。其中有机氯农药的浓度范围 6 .6 0～ 32 .6ng/L(其中HCHs:3.5 1～ 2 7.8ng/L ,均值 8.5 7ng/L ;DDTs:0 .95～ 2 .2 5ng/L ,均值 1.45ng/L) ,多氯联苯的浓度为 0 .0 8～ 1.6 9ng/L ,同国内外其他港口海区相比较 ,其污染程度相对较低。同时 ,对有机氯污染的分析表明 ,发现近年来仍有有机氯的污染输入 ,其农药的使用主要集中在六六六和滴滴涕上 ;多氯联苯和有机氯农药在厦门西港有着相似的分布及来源特征。organochlorine pesticides and 12 polychlorinated biphenyls(PCBs) at the sruface water in Xiamen Harbour were determined. The range of organochlorine pesticides was 6.60～32.60 ng/L, and the PCBs concentrations were 0.08～1.69 ng/L. Compared with the results of other harbor and estuaries, it showed that the contamination for organic chlorine pollutants was more slight than those of others. At the same time, it was found that organochlorine pesticides and PCBs have the similar geological destribution and resources.福建省自然科学基金!项目 (D9810 0 0 3