存在空箱调运的非对称运输市场定价策略研究

考虑空箱调运成本,本文对垄断和双寡头市场分别研究运输企业在两条相向路径上的定价问题。对于垄断市场,建立了运输企业最优定价策略,并刻画出无空箱调运的潜在需求不平衡区间。对于双寡头市场,考虑同一路径上不同企业潜在运输需求不等的现实情境,求解了非对称企业的伯川德纳什均衡,给出最优定价策略。研究发现,无空箱调运并不意味着较高利润,运输企业没有必要刻意消除空箱调运现象。另外,增加单位载货运输成本和竞争强度会降低企业利润,而提升单位空箱重置成本、价格敏感度和市场不对称程度都会增大企业利润。     

多重多级子结构方法与模态综合法的对比研究

利用高精度多重多级子结构方法与传统的动力子结构模态综合法（MSC.Nastran超单元法）进行对比研究．该算法采用Lanczos方法与子结构周游树技术,考虑了各子结构内部自由度对整体求解的贡献,算法精度得到显著提高,并与不作凝聚的单一整体结构分析具有相同的计算精度．数值结果表明多重多级子结构方法相比于模态综合法在子结构划分及多层次调用上更为灵活,计算结果不受复杂子结构划分方式的限制和出口点选取的影响,在高阶频率的计算方面精度更好．     

量子密码协议的错误序列模型分析

量子密码协议具有无条件安全特性,其安全性通过窃听检测来保证.为了提高信息序列错误率的估计值精确度,提出了一种错误序列模型分析方法,通过构造法得到错误序列的二阶统计特性,从而通过经典方法对信息序列中错误序列进行预测,最后得到信息序列的错误率.在单次运行协议情况下,提高了窃听检测的精度,适用于其他量子密码协议. 关键词： 量子密码 最佳预测 窃听检测 序列重构     

Security proof of counterfactual quantum cryptography against general intercept-resend attacks and its vulnerability

Counterfactual quantum cryptography,recently proposed by Noh,is featured with no transmission of signal particles.This exhibits evident security advantages,such as its immunity to the well-known photon-number-splitting attack.In this paper,the theoretical security of counterfactual quantum cryptography protocol against the general interceptresend attacks is proved by bounding the information of an eavesdropper Eve more tightly than in Yin’s proposal [Phys.Rev.A 82 042335(2010)].It is also shown that practical counterfactual quantum cryptography implementations may be vulnerable when equipped with imperfect apparatuses,by proving that a negative key rate can be achieved when Eve launches a time-shift attack based on imperfect detector efficiency.     

Role of highest occupied molecular orbitals in molecular field-free alignment by a femtosecond pulse

This paper studies the molecular rotational excitation and field-free spatial alignment in a nonresonant intense laser field numerically and analytically by using the time-dependent Schr?dinger equation. The broad rotational wave packets excited by the femtosecond pulse are defined in conjugate angle space, and their coefficients are obtained by solving a set of coupled linear equations. Both single molecule orientation angles and an ensemble of O₂ and CO molecule angular distributions are calculated in detail. The numerical results show that, for single molecule highest occupied molecular orbital (HOMO) symmetry σ tends to have a molecular orientation along the laser polarization direction and the permanent dipole moment diminishes the mean of the orientation angles; for an ensemble of molecules, angular distributions provide more complex and additional information at times where there are no revivals in the single molecule plot. In particular, at the revival peak instant, with the increase of temperature of the molecular ensemble, the anisotropic angular distributions with respect to the laser polarization direction of the π _g orbital gradually transform to the symmetrical distributions regarding the laser polarization vector and for two HOMO configurations angular distributions of all directions are confined within a smaller angle when the temperature of the molecular ensemble is higher.     

Network-topology-adaptive quantum conference protocols

As an important application of the quantum network communication,quantum multiparty conference has made multiparty secret communication possible.Previous quantum multiparty conference schemes based on quantum data encryption are insensitive to network topology.However,the topology of the quantum network significantly affects the communication efficiency,e.g.,parallel transmission in a channel with limited bandwidth.We have proposed two distinctive protocols,which work in two basic network topologies with efficiency higher than the existing ones.We first present a protocol which works in the reticulate network using Greeberger-Horne-Zeilinger states and entanglement swapping.Another protocol,based on quantum multicasting with quantum data compression,which can improve the efficiency of the network,works in the star-like network.The security of our protocols is guaranteed by quantum key distribution and one-time-pad encryption.In general,the two protocols can be applied to any quantum network where the topology can be equivalently transformed to one of the two structures we propose in our protocols.     

结构拓扑优化中变量连接算法研究与软件实现Research and software implementation of variable connection algorithm for structural topology optimization

结构拓扑优化的变量连接,是通过对设计变量之间添加约束关系,从而得到特定的拓扑优化构型,使得优化结果能够满足工程上的特殊要求和工艺制造技术的限制。针对拓扑优化中的几类过滤形式及灵敏度分析,给出了考虑变量连接的计算公式;基于自主研发的SiPESC软件集成化平台,在SiPESC ．TOPO拓扑优化模块上进行二次开发,构建了拓扑优化的变量连接算法框架,其核心思想是基于面向对象设计方法和软件设计模式,实现算法与数据分离。详细阐述了变量连接的作用方式,以及软件框架通用接口设计方案,并通过数值算例验证了其在静力问题、动力问题和热传导问题上的可行性。     

基于界面主从位移控制的频响子结构方法

在复杂工程结构频响子结构分析中,各个子结构的频响函数往往是由不同的部门获得,各个子结构的频响函数可能是在不同的坐标系下得到,亦或有些子结构具有某种对称性,这需要对相应的子结构频响函数进行旋转和镜像变换后才能进行整体拼接。此外,子结构拼接时交界面的连接点有时可能存在不一致,为了满足位移协调和力平衡条件,本文基于界面主从位移控制原理,提出一种改进的频响子结构方法,该方法既能考虑子结构的旋转和镜像变换,也能考虑子结构界面间的柔性连接,并可大幅提高计算效率。当界面位移控制阵为单位阵时,改进的方法退化为传统的频响子结构方法。数值算例验证了所提方法的正确性和有效性。     

结构优化半解析灵敏度及误差修正改进算法

提出结构半解析灵敏度分析及其针对刚体位移的误差修正方法的改进算法,构建灵敏度分析与误差修正项可分离形式.该方法实现简便,数值精度不受摄动步长与单元数目的影响.首先从总体角度推得静力问题的误差修正半解析灵敏度分析方法,提出了位移误差修正灵敏度列式,并给出算法实施途径;然后将此思路推广于自振频率、屈曲临界载荷问题,提出了相应的计算步骤.随后,给出梁单元与壳单元误差修正项的具体推导方法,并分别使用两种单元构建有限元模型进行算例测试.结果表明,该方法适用于多种分析类型,数值精度不受单元数目与摄动步长的影响.由于灵敏度分析与误差修正项可以分开计算,该方法支持将误差修正项直接叠加于灵敏度求解结果进行误差修正,使已有灵敏度分析程序得到充分利用.尤其对于复杂工程结构的优化设计,特别是形状优化设计以及尺寸、形状混合优化设计,相比于原误差修正方法,实现更为简便,效率有所提升,能为半解析灵敏度分析方法及其程序实现提供新的思路.     

基于开放式结构有限元系统 SiPESC.FEMS平板壳单元研发

基于开放式结构有限元系统SiPESC.FEMS的单元计算模块的设计模式,研发设计一种通用的平板壳单元计算框架。考虑板壳单元的组合关系和程序编制过程中的重用性及灵活性等特点,采用了软件设计中的构造器(Builder)模式实现不同的组合单元。本框架具有很好的通用性和可扩展性,为有限元程序研发提供了一个新的方式;同时,系统能够处理复杂荷载和边界条件,并可灵活实现不同类型单元的组合分析。本文利用此方法构造五种平板壳单元,通过数值算例分析对比讨论其性能,为选取合适的平板壳单元类型进行结构数值分析提供参考。