Theoretical Calculations on the Second-order Nonlinear Optical Property of Chiral Bis-corroles

The second-order nonlinear optical (NLO) properties of 5,10,15-triphenylcorrole (TPC), 5,10,15,20-tetraphenylporphyrin (TPP) and L-amino acid bridged bis-corroles 1, 2, 3 and 4 have been calculated by using TDHF/PM3 method based on the RHF/6-31G (TPC and TPP) or semiempirical PM3 (1, 2, 3, 4) optimized geometries. Calculation results showed TPC and TPP have C1 and D2h symmetry, respectively when N-H protons are localized on the nitrogen atoms. TPC is the second-order NLO active chromophore due to the cancellation of centrosymmetrical structure and its first hyperpolarizability β increases to 11.524×10-30 esu. Under electrical dipole approximation, β values of bis-corroles 1, 2, 3 and 4 vary from 9.831×10-30 to 14.221×10-30 esu, and no much improvement in the first hyperpolarizability was observed as compared to TPC monomer. However, β values of bis-corroles 1, 2, 3 and 4 are improved by about 4 times as compared to their bis-porphyrin counterparts. The analysis of β components indicates that β of this kind of bis-corroles is mainly contributed from its radial component βr. With the variation of amino acid side chains, βHRS, β, βxyz, βr and βa of bis-corroles change remarkably. Chiral L-amino acid bridged bis-corroles 2, 3 and 4 have a right-handed helix structure, and their chiral component βxyz matches βxyz ∝ r2ζ/L4 (helix parameters), showing the second-order chiral NLO response of these bis-corroles could be described by one-electron helical model theory. It was found that the radial component βr of chiral helix bis-corroles also matches β r ∝ r2ζ/L4.     

A Factorisation of Diffusion Measure and Finite Sample Path Constructions

In this paper we introduce decompositions of diffusion measure which are used to construct an algorithm for the exact simulation of diffusion sample paths and of diffusion hitting times of smooth boundaries. We consider general classes of scalar time-inhomogeneous diffusions and certain classes of multivariate diffusions. The methodology presented in this paper is based on a novel construction of the Brownian bridge with known range for its extrema, which is of interest on its own right.      

Formation and local electronic structure of Ge clusters on Si（111）-7×7 surfaces

We report the formation and local electronic structure of Ge clusters on the Si(111)-7$\times $7 surface studied by using variable temperature scanning tunnelling microscopy (VT-STM) and low-temperature scanning tunnelling spectroscopy (STS). Atom-resolved STM images reveal that the Ge atoms are prone to forming clusters with 1.0~nm in diameter for coverage up to 0.12~ML. Such Ge clusters preferentially nucleate at the centre of the faulted-half unit cells, leading to the `dark sites' of Si centre adatoms from the surrounding three unfaulted-half unit cells in filled-state images. Bias-dependent STM images show the charge transfer from the neighbouring Si adatoms to Ge clusters. Low-temperature STS of the Ge clusters reveals that there is a band gap on the Ge cluster and the large voltage threshold is about 0.9~V.     

氧碘化学激光器输出功率的估算

 建立了激光在工作时的动态模型,即假设在单位时间内,激光介质的粒子数全部被泵浦到上能级。引入激光介质重复泵浦次数的概念,根据能量守恒原理,通过分析氧碘化学激光器(COIL)的传能机理,计算了沿气流方向变化的碘原子上能级的弛豫时间及沿气流方向变化的碰撞传能时间,并且计算了碘原子在出光区内被单重态氧反复泵浦的次数及相应的残余单重态氧数目,从而计算出碘原子在出光区的反复泵浦次数,修正了原计算COIL输出功率的公式。理论计算与实验结果均表明：当碘流量过低时,增益小于损耗,激光器不能起振;当增大碘流量时,激光输出功率也逐步增大,反复泵浦次数逐渐减少;当碘流量继续增大时,激光输出功率达到最大,且在一定碘流量变化范围内基本保持稳定;但随着碘流量的进一步增大,激光输出功率却逐步下降。     

带到达时间的加工时间离散可控的单机排序问题1|rj , dm|Cmax +TPC的FPTAS算法

考虑工件加工时间离散可控的单机分批排序问题,目标函数是极小化最大完工时间与加工费用之和.对于工件不同时到达的情况,本文给出了FPTAS算法.     

论网络时代企业图书馆信息服务的发展趋势及对策

分析了在信息时代网络环境下图书馆信息服务的发展趋势,研究了在当前形势下企业图书馆的发展对策.     

N次随机丢包的被动队列管理算法

针对主动队列管理参数设置敏感、消耗大量资源等问题,提出了N次随机丢包的被动队列管理算法.当队列满时,根据当前网络中与路由节点链接的发送端数目,决定丢弃数据包N的值,然后再采用改进的随机丢弃策略丢弃N个数据包.新的算法与其他被动随机丢弃策略相比,克服了弃尾队列管理的缺陷,能够更快地响应网络拥塞,提高了网络传输性能,同时也能够在一定程度上保证公平性,NS2仿真表明了算法的有效性.     

逻辑东渐与中国近代时期哲学的革新

西方逻辑在中国近代时期（1840—1949年）的第二次东渐,对这一时期中国哲学的发展产生了显著影响。具体表现在以下三个方面：第一,逻辑东渐促成了当时哲学观念的新变化;第二,逻辑东渐为哲学研究提供了新的视域和方法;第三,逻辑东渐诱发了“逻辑哲学”这一全新的学术研究方向和研究领域出现。西方逻辑东渐对中国近代时期哲学革新所产生的积极影响,标志着这一时期的知识分子对中国新文化建设蓝图的一种有益探索——妥善处理古今中外人类历史上所产生的进步文化成果,扬长补短,择优而从。     

压裂液作用后对页岩气体传质效率影响实验研究

页岩储层具有低孔、低渗特征。经压裂改造形成多裂缝网络,气体的产出流经致密基块-天然裂缝-水力裂缝等串并联耦合传质路径。压裂过程中压裂液的侵入会造成储层流体敏感性及水锁等损害,影响气体传质效率;因此有必要研究压裂液作用后对页岩气体传质效率的影响。设计实验,进行页岩岩样人工缝预处理,自行设计串、并联气体传质实验方法及装置,探讨了压裂液作用后对页岩气体传质效率的影响。结果表明,压裂液作用后,"串、并联"配置关系传质能力均下降,基块、裂缝岩样传质能力损害程度分别达到30%和80%左右;同时裂缝和基质孔喉分别对"并联"和"串联"配置传质效率起主导作用。因此,多裂缝网络中应以裂缝基质保护共举为目标,优化清洁压裂液,同时设计合理开发方案,提高气藏的最终采收率。     

一个嵌入式实时操作系统的设计

为了开发自主产权的嵌入式实时操作系统，结合uCLinux内存管理的特性和RTAI的实时特性，在总体架构、内存管理、进程管理、异常中断处理和定时器等主要模块上做了精心的设计，开发出了具有硬实时特性的嵌入式实时操作系统——ZDRTOS．