首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 218 毫秒
1.
基于扩散速度方法粘性流场的离散涡数值模拟   总被引:1,自引:0,他引:1  
基于扩散速度方法粘性流场的离散涡数值模拟吴文权,李春,卜千里(上海机械学院上海200093)关键词:扩散速度模型,粘性流场,离散涡方法。NUMERICALSIMULATIONOFVISCOUSFLOWFIELDSUSINGDIFFUSIONVELOC...  相似文献   

2.
我们制作了一种可在6—11V偏压范围内均匀发射可见光的新型金属—绝缘体—金属结型发光器件,其内层结构是Al-Al2O3-MgF2-An(Cu),其承受偏压、单位面积发光功率及相应的外量子效应高过迄今已知的M-O-M遂道结型发光器件.本文首次报导并论证了这一由Schottky热电子所激发的光发射及其物理图象:Schottky热电子在AO(Cu)-真空界面激发表面等离极化激元(SPP);Au(Cu)-真空界面的SPP通过表面粗糙度与外光子耦合.这一图象与该器件的电流—电压(I—V)、电流—温度(I-T)关系及其发射光谱的主要特征一致.  相似文献   

3.
用角分辨XPS(Angle-resolvedXPS)研究研究了HS(CH2)10COOH(I)HS(CH2)3OC6H4N=NC6H4(CH2)7CH3(II)和HS(CH2)6HS(Ⅲ)3种分子在Au膜表面制备的自组装单分子层,得出了(I)中S原子,(Ⅱ)中S,N原子距膜表面的垂直距离,并结合构象分析确定了分子的取向和倾角,对分子(Ⅲ)则得出分子在紫外光照射下氧化反应的选择性,发现氧化主要在底层  相似文献   

4.
赵策洲  刘恩科 《光学学报》1994,14(12):324-1328
提出了一种简便可行的SOI无间距定向耦合光开关(BOA型-Bifurcation Optique Active)模型分析方法,采用等离子体色散效应这种光开关的电学调制机理;而用pn结大注入效应分析开拳电学性质;并根据大截面单模SOI脊形波导理论和上棕分析,设计了利用双模干淑机制工作的这种器件的结构参数和电学参数。  相似文献   

5.
混煤氮的热解析出特性及燃料NO_x的形成规律   总被引:5,自引:0,他引:5  
混煤氮的热解析出特性及燃料NO_x的形成规律邱建荣,马毓义,曾汉才,吕焕尧,喻秋梅(华中理工大学煤燃烧国家重点实验室武汉430074)关键词:混煤,NO_x,混合比,燃烧。EMISSIONOFNITROGENCOMPOUNDSANDNO_xFORMAT?..  相似文献   

6.
本文使用基于ab inito RHF,UHF/STO-3GMO法辅以能量梯度方法优化CIPS,CISP的基态(S0)和第一激发叁态(T10第一激发单态(S1)的平衡几何构型,及CIPS→CISP在异构化过程中各势能剖面的过滤态的几何构型。并用MP4/6-31G进行了相关校正。所得CIPS分子基态(1A)的几何构型计算结果与IR及Raman实验数据吻合,并解释了至今尚未发现CIPS分子的实验事实。预  相似文献   

7.
丙烯酰胺在反向微乳液中聚合反应的研究   总被引:4,自引:0,他引:4  
在水-AOT-甲苯反向微乳液体系中,选用了四种引发剂AIBN,(NH4)2S2O3,NaHSO3,MnSO4-O2-NaHSO3,开展丙烯酰胺的聚合反应的研究,其中着重研究引发剂的浓度,反应温度等因素对聚合分子量的影响。  相似文献   

8.
利用电学测量方法结合二次离子质谱(SIMS)技术对金属Ag与Al与YBa2Cu3O7-x(YBCO)超导薄膜接触界面电学性质和扩散特征进行了测试分析,分析结果显示由于Ag和Al具有不同的化学性质,二与YBCO界面的互扩散特性有明显不同,这些不同影响到接触界面的电学性质和接触窗口下YBCO超导性能,在Ag/YBCO样品中,在高于350℃以上的温度下氧气氛中退火将引起Ag和O的界面互扩散,但对YBC  相似文献   

9.
粒子一转子模型推广到用于描述A-150区奇A梭超形变核态,首次成功地拟合了 ̄149Gd(b1)和 ̄153Dy(b1)能量的AI=2Staggering.  相似文献   

10.
作者索引     
Cumulative Author Index for Vol.22,No.1~4 and Supp.AN Yuying(安毓英)p.143Arakawa Y Supp.57,61,67BAE HyunsooK(裴贤淑)p.55BAO Ximao(鲍希茂)p.339BAN Shiliang(班士良)p.33Bentham F C Supp. 103BI Zhaorong(毕朝荣)Supp.57CAI Shuhui(蔡淑惠)p.172,182CAI Weiying(蔡炜颖) p.107,161Cao Lixin(曹…  相似文献   

11.
We present the numerical and experimental study on the coherent beam combining of fibre amplifiers by means of simulated annealing (SA) algorithm. The feasibility is validated by the Monte Carlo simulation of correcting static phase distortion using SA algorithm. The performance of SA algorithm under time-varying phase noise is numerically studied by dynamic simulation. It is revealed that the influence of phase noise on the performance of SA algorithm gets stronger with an increase in amplitude or frequency of phase noise; and the laser array that contains more lasers will be more affected from phase noise. The performance of SA algorithm for coherent beam combining is also compared with a widely used stochastic optimization algorithm, i.e., the stochastic parallel gradient descent (SPGD) algorithm. In a proof-of-concept experiment we demonstrate the coherent beam combining of two 1083~nm fibre amplifiers with a total output power of 12~W and 93% combining efficiency. The contrast of the far-field coherently combined beam profiles is calculated to be as high as 95%.  相似文献   

12.
李建龙  吕百达 《中国物理 B》2008,17(5):1840-1844
Taking the Gaussian Schell-model beam as a typical example of partially coherent beams, this paper applies the simulated annealing (SA) algorithm to the design of phase plates for shaping partially coherent beams. A flow diagram is presented to illustrate the procedure of phase optimization by the SA algorithm. Numerical examples demonstrate the advantages of the SA algorithm in shaping partially coherent beams. An uniform flat-topped beam profile with maximum reconstruction error RE 〈 1.74% is achieved. A further extension of the approach is discussed.  相似文献   

13.
梁文锡  张静娟  吕俊峰  廖睿 《中国物理》2001,10(12):1129-1135
We have designed a spatially quantized diffractive optical element (DOE) for controlling the beam profile in a three-dimensional space with the help of the simulated annealing (SA) algorithm. In this paper, we investigate the annealing schedule and the neighbourhood which are the deterministic parameters of the process that warrant the quality of the SA algorithm. The algorithm is employed to solve the discrete stochastic optimization problem of the design of a DOE. The objective function which constrains the optimization is also studied. The computed results demonstrate that the procedure of the algorithm converges stably to an optimal solution close to the global optimum with an acceptable computing time. The results meet the design requirement well and are applicable.  相似文献   

14.
The trade-off between diffraction efficiency and uniformity is studied when a binary phase-only diffractive optical element (DOE) is designed for transforming a Gaussian beam to an expanded squared uniform intensity distribution. The simulated annealing (SA) algorithm and Fresnel diffraction theory are applied in our design. Two types of cost functions are utilized in the SA algorithm, and the cases of different incident Gaussian diameters and bright-area sizes of the target patterns are studied. The mechanisms of reducing nonuniformity by the two cost functions are essentially different, and the mechanism combining nonuniformity and the intensity difference between the reconstructed and target patterns has better results. Satisfactory performance can be obtained under the trade-off between them.  相似文献   

15.
The coherence transformation and distillation for a class of special mixed coherent states of rank-2 under incoherent operations (IO) is discussed. Similar to the entanglement transformation for mixed entangled states, the catalytic coherence transformation for this class of special mixed coherent states is analyzed. On the one hand, it is found that some of the mixed coherent states can be converted into other mixed coherent states under IO. But for those mixed coherent states which fail in the coherence conversion under IO, the catalytic coherence manipulation can solve this problem. In this case, a mixed coherent state cannot be converted into another under IO, while the coherence transformation can be realized with the help of coherence-assisted incoherent operations, that is, catalytic coherence transformation. On the other hand, these special mixed coherent states can be distilled into the maximally pure coherent states or mixed states of arbitrary dimensions by strictly incoherent operations with certain probabilities. Finally, the coherence transformation of this type of mixed states can be generalized to the case of higher rank in a similar way, which is discussed at the end of this paper.  相似文献   

16.
游开明  林燕玲  王友文  陈列尊  戴志平  陆世专 《物理学报》2013,62(14):140203-140203
基于Dini级数展开, 导出了p(>0) 阶准离散Hankel变换(the pth-order quasi-discrete Hankel transform based on Dini series expansion, pDQDHT)算法, 并给出了该算法在光束传输中的应用. 通过不同输入函数分别对pDQDHT算法进行测试及光束通过透镜传输的应用实例, 结果表明: pDQDHT算法不仅精度高于现有的Hankel变换算法, 可以进行多次正、逆变换, 能广泛应用于光束分步传输问题, 而且执行速度也与一般的快速Hankel变换算法相当. 关键词: Dini级数展开 高阶Hankel变换 光束传输  相似文献   

17.
Arrays with sparse and random sensor deployment are known to be capable of delivering high quality far-field images without grating lobes. This raises the question of whether or not this idea can be applied to near-field imaging as well. To answer this question that has not yet been widely investigated in previous research, numerical simulations are undertaken in this paper to optimize the microphone deployment for both far-field and near-field arrays with the latter being the main focus. In the simulation, a recently introduced near-field equivalent source imaging (NESI) technique is employed for the near-field imaging. Global optimization techniques including the simulated annealing (SA) algorithm and the intra-block Monte Carlo (IBMC) algorithm are exploited to find the optimal microphone position efficiently. The combined use of the SA and the IBMC algorithms enables efficient search for satisfactory deployment with excellent beam pattern and relatively uniform distribution of microphones. In the near-field optimization, a special kind of beam pattern and cost function definition is used for the multiple-input-multiple-output (MIMO) imaging problem. As indicated by the simulation results, random deployment of microphones is necessary to avoid grating lobes in far-field imaging. In the near-field simulation, all results suggest that the optimal near-field array is the uniform rectangular array (URA) and the random deployment presents no particular benefit in near-field imaging.  相似文献   

18.
部分相干平顶高斯光束通过球差透镜的聚焦特性   总被引:2,自引:0,他引:2       下载免费PDF全文
 基于部分相干光的传输理论,研究了部分相干平顶高斯光束通过球差透镜聚焦后轴上点的光强分布。数值计算表明:轴上最佳聚焦点随着球差从负到正的变化而向几何焦点方向移动;光束阶数越大,实现最佳聚焦点越过几何焦点所需的正球差值越小;正负球差对应的最佳聚焦点始终分居于无球差时最佳聚焦点的两侧;轴上最佳聚焦点的光强随着球差从负到正的变化而变小;当正负球差绝对值较大时,光强随球差的变化较为缓慢,而在球差值为0附近,光强随球差的变化比较剧烈。  相似文献   

19.
基于部分相干光的传输理论,研究了部分相干平顶高斯光束通过球差透镜聚焦后轴上点的光强分布。数值计算表明:轴上最佳聚焦点随着球差从负到正的变化而向几何焦点方向移动;光束阶数越大,实现最佳聚焦点越过几何焦点所需的正球差值越小;正负球差对应的最佳聚焦点始终分居于无球差时最佳聚焦点的两侧;轴上最佳聚焦点的光强随着球差从负到正的变化而变小;当正负球差绝对值较大时,光强随球差的变化较为缓慢,而在球差值为0附近,光强随球差的变化比较剧烈。  相似文献   

20.
软硬件划分是可重构指令集处理器在软硬件协同设计中的关键问题,通过对比遗传算法和经典模拟退火算法的优缺点,提出改进遗传算法的适应度函数,同时将Tsallis接受准则引入到经典模拟退火当中。其思路是用遗传算法的结果来制约模拟退火算法产生的随机状态,然后由模拟退火的接受准则以及产生的随机状态函数对遗传算法的种群进行更新,从而找到全局近似最优解。实验结果证明,改进算法与单一遗传算法以及经典模拟退火算法相比,其收敛速度和适应度更好,找到全局近似最优解的概率更大。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号