Simulation studies on the polarized positron generation from circularly polarized gamma-rays

Polarized positrons can be generated through the electron-positron pair creation from circularly polarized gamma-rays hitting a conversion target. Laser-Compton scattering is an efficient method to generate circularly polarized gamma-rays. Simulation studies on these two processes have been done with the Monte Carlo codes, CAIN and GEANT4. Using CAIN to simulate the Laser-Compton scattering process, the energy spectrum of the generated polarized photons could be obtained. GEANT4 was used to study the yield, energy spectrum and the mean polarization of the positrons emanating from the conversion target. To increase the yield of the generated positrons, an optimization study on the thickness of conversion target was also performed.     

Prediction of thermal conductivity of polymer-based composites by using support vector regression

Support vector regression (SVR) combined with particle swarm optimization (PSO) for its parameter optimization, was proposed to establish a model to predict the thermal conductivity of polymer-based composites under different mass fractions of fillers (mass fraction of polyethylene (PE) and mass fraction of polystyrene (PS)). The prediction performance of SVR was compared with those of other two theoretical models of spherical packing and flake packing. The result demonstrated that the estimated errors by l...     

“非平均区间数”计算及其在政府决策信息系统中的应用

本文在已有的“区间数”定义及排序算法的基础上 ,针对层次分析法提出了更加灵活 ,准确的描述主观评判的“非平均区间数”概念及其排序算法 .并结合政府决策信息系统阐述了“非平均区间数”的应用     

光电列阵元件光谱响应的整体测试法

本文针对列阵元件的特点,提出了对其光谱响应进行整体测试的方法。实测结果与误差分析计算表明,整体测试法是一种准确稳定和易行的方法。     

一个新的凋亡抑制蛋白P49的表达及氨基酸序列分析

从海灰翅夜蛾核型多角体病毒（SpliNPV)中新发现的p49基因可抑制病毒感染引起的草地贪夜蛾细胞Sf9的凋亡，用杆状病毒表达系统Bac to Bac克隆表达并收获P49蛋白，发现所测定的表达蛋白的氨基酸序列与由核苷酸推导的氨基酸序列一致，证明p49基因经克隆转染后得到正确表达，P49蛋白上－^91TVTDG^95－氨基酸序列为Caspase识别结构，比较P35与P49蛋白，两蛋白同源性约为48．8％，且都具Caspase识别和切割的氨基酸序列。     

NON-NEGATIVE SOLUTIONS FOR A CLASS OF NON-POSITONE PROBLEMS

1IntroduInthispaperwestudyill(.)(l}xlsl(.)ll(:()noTI-1)ega,t]v(3s(>1lltionsfort,h(i1,woilo]lit,boundaryvalueproblemsu\ry;l;(:i.t>(v,>\,:t),:j:=fti-i'...ifn(j)>l),A>0isdcollstanta,f,dj'e(!'l,.,ti,fi<,,f(())<0(l.:i)111.of)i(lfllsifs{.1.l:)-(.I.2)havel,ecnsi…     

夹心半群S(X,Y,θ)上的α-同余

本文讨论了夹心半群T(X,Y,θ)上的α-同余与集合Y上Tθ-等价关系之间的联系,证明了对于每个Tθ-等价关系E,夹心半群同余格C(T(X,Y,θ))的完全子格γ-1(E)中的最大元是一个α-同余,并判明Symons同余l,d都是α-同余.对于某些拓扑空间X,Y,确定了夹心半群S(X,Y,θ)上的最小(最大)真α-同余.     

多条形电极束流能散度探测器的张角优化

 采用Surperfish对北京正负电子对撞机的多条形电极束流能散度探测器进行了电磁场模拟计算。在带模拟束流的情况下，计算分析了探测器对束流位置和能散度的分辨能力与电极张角之间的关系，首次计算了条形电极间的电容耦合综合强度。电极张角优化结果表明：在不考虑噪声水平的情况下，电极张角为20°时，探测器的灵敏度和分辨率达到最优。而当噪声影响很大时，可以适当增加电极张角，同时考虑减小噪声的措施。     

Mechanochromic Photonic‐Crystal Fibers Based on Continuous Sheets of Aligned Carbon Nanotubes

A new family of mechanochromic photonic‐crystal fibers exhibits tunable structural colors under stretching. This novel mechanochromic fiber is prepared by depositing polymer microspheres onto a continuous aligned‐carbon‐nanotube sheet that has been wound on an elastic poly(dimethylsiloxane) fiber, followed by further embedding in poly(dimethylsiloxane). The color of the fiber can be tuned by varying the size and the center‐to‐center distance of the polymer spheres. It further experiences reversible and rapid multicolor changes during the stretch and release processes, for example, between red, green, and blue. Both the high sensitivity and stability were maintained after 1000 deformation cycles. These elastic photonic‐crystal fibers were woven into patterns and smart fabrics for various display and sensing applications.