摘要：化学取代是有效调节分子电导,产生多通道输运、量子干涉效应和其他机制的关键方法.但分子骨架和侧基之间存在复杂的相互作用,目前仍未被研究清楚.在本工作中,我们结合扫描隧道显微镜裂结实验技术和第一性原理计算方法,深入研究了具有不同σ和π侧基的分子电导.实验结果及理论分析表明,σ侧基的加入引起了分子前线轨道的对称性破缺并加剧了分子内散射,从而导致电导的降低.相反,π侧基引入了额外的电荷传输通道,实现了电荷传输的多通道效应,增加了分子的电导.这些发现为未来分子功能化和分子电子器件的设计提供了坚实的基础.

摘要：Most of the existing image encryption schemes with the substitution-diffusion structure are not secure and *** this letter,a chaos-based pseudo-random bit generator with good statistical properties is proposed,where a simple post-processing by compressing is employed.A new adaptive image encryption scheme with the substitution-diffusion architecture is designed using the new pseudo-random bit *** the scheme,the session key for the pseudo-random bit generator is dependent on the content of the image which ensures that the scheme can effectively resist knownplaintext and chosen-plaintext *** analysis and computer simulation indicate that the proposed algorithm is efficient and highly secure.

摘要：There are a lot of security issues in block cipher *** analysis and enhanced design of a dynamic block cipher was ***,the safety of ciphertext was enhanced based on confusion substitution of S-box,thus disordering the internal structure of data blocks by four steps of matrix ***,the diffusivity of ciphertext was obtained by cyclic displacement of bytes using column ambiguity *** dynamic key was finally generated by using LFSR,which improved the stochastic characters of secret key in each of round of *** safety performance of proposed algorithm was analyzed by simulation *** results showed the proposed algorithm has a little effect on the speed of encryption and decryption while enhancing the ***,the proposed algorithm has highly scalability,the dimension of S-box and the number of register can be dynamically extended according to the security requirement.

摘要：我们将实体嵌入问题看作同时完成两个不同但相关的嵌入任务(实体嵌入和关系嵌入)的联合优化问题,并在联合嵌入框架下求解该问题。在该嵌入框架下,我们设计了联合评分函数,用以对实体和关系间的相关性实例进行量化评价,并将评分函数融入最大间隔学习方法中,使用知识库中的上下文信息学习实体与关系的嵌入向量。通过求解联合优化问题,我们的设计有效地表达了嵌入空间的固有拓扑结构。实验结果证实了我们的嵌入框架在表达不同关系的语义相关性和进行知识推理中的关系预测时的有效性。

摘要：本文提出一种在特殊任务下基于Chebychev映射的移动机器人混沌全覆盖路径规划器的设计新策略。所设计的混沌路径规划器包含一个二维的Chebychev映射,该映射由两个一维的Chebychev映射构建而成。对规划器所产生的时间序列,进行反正弦变换,可以改善系统的混沌特性和均匀分布特性,从而提高机器人在完成特殊任务时的覆盖率和随机特性。通过仿射变换,Chebychev混沌系统映射到机器人工作空间的可行区域内,然后设计有障碍物环境下全覆盖路径规划的通用方法。仿真结果显示,所设计的混沌路径规划器在可行空间能够安全运行,不需要设计避障算法。所设计策略能够满足特殊任务下随机性、遍历性和高效率的需求。

摘要：标准的软件开发周期很大程度上取决于利益相关方的需求。软件开发全程围绕需求设计和管理。考虑到时间和资源的限制,必须分清哪些是必须首先考虑的高优先级需求。已有的需求排序架构缺少对历史数据的记录,而这些历史数据有助于从类似项目中方便地选取最适合的需求排序技术。本文中,我们提出一种名为Re Pizer的软件需求排序架构,该架构与一种选定的需求排序技术联合使用,可以基于给定标准(如开发成本),为软件需求优先级排序。Re Pizer通过从需求库提取历史数据,为软件需求工程师决策提供协助。此外,Re Pizer提供了对整个项目的全景式视角,以确保对资源的审慎使用。基于Re Pizer架构,采用已有的两种需求排序技术:计划博弈(planning game,PG)和层级分析(analytical hierarchy process,AHP),分别比较各自的预期准确度和易用程度。结果表明,采用计划博弈时,Re Pizer性能更佳。

摘要：Cobalt nanoparticles(NPs)catalysts are extensively used in heterogeneous catalytic reactions,and the addition of alkali metal promoters is a common method to modulate the catalytic performance because the catalyst's surface structures and morphologies are sensitive to the addition of ***,the underlying modulation trend remains ***,the adsorption of alkali metal promoters(Na and K)on the surfaces of face-centered-cubic(FCC)and hexagonal-closest packed(HCP)polymorphous cobalt was systematically investigated using density functional ***,the effect of alkali promoters on surface energies and nanoparticle morphologies was revealed on the basis of Wulff *** FCC-Co,the exposed area of the(111)facet in the nanoparticle increases with the adsorption coverage of alkali metal ***,the(311),(110),and(100)facets would disappear under the higher adsorption coverage of alkali *** HCPCo,the Wulff morphology is dominated by the(0001)and(1011)facets and is independent of the alkali metal adsorption *** work provides insights into morphology modulation by alkali metal promoters for the rational design and synthesis of cobalt-based nanomaterials with desired facets and morphologies.

摘要：A laterally diffused metal-oxide-semiconductor （LDMOS） device design with an enhanced p-well and double p-epitaxial structure is investigated for device ruggedness improvement while keeping its high device per- formance under high frequency. Based upon the device design, radio-frequency （RF） LDMOS transistors for GSM （global system for mobile communication） application have been fabricated by using 0.35/zm CMOS technolo- gies. Experimental data show that the proposed device achieves a breakdown voltage of 70 V, output power of 180 W. The RF linear gain is over 20 dB and the power added efficiency （PAE） is over 70% with the frequency of 920 MHz. In particular, it can pass the 20 ： 1 voltage standing wave ratio （VSWR） load mismatch biased at drain DC supply voltage of 32 V and output power at 10-dB gain compression point （P10dB）. The device ruggedness has been remarkably improved by using the proposed device structure.

摘要：The relay node with linear relaying transmits the linear combination of its past received *** optimization of two-hop relay channel with linear relaying is discussed in this *** capacity for the two-hop Gaussian relay channel with linear relaying is derived,which can be formulated as an optimization problem over the relaying matrix and the covariance matrix of the signals transmitted at the *** is proved that the solution to this optimization problem is equivalent to a "single-letter" optimization *** also show that the solution to this "single-letter" optimization problem has the same form as the expression of the rate achieved by Time-Sharing Amplify and Forward(TSAF).In order to solve this equivalent problem,we proposed an iterative *** results show that if channel gain of one hop is relatively smaller,the achievable rate with TSAF is closer to the max-flow min-cut capacity bound,but at a lower complexity.

摘要：The design of an ultra-compact SOI-based 1×2 3 dB multimode interference(MMI) coupler is *** symmetric multimode interference structure and deeply-etched parabolically tapered multimode waveguide are used in the *** length of the device is reduced by about 87% compared with general multimode interference straight *** on effective index method(EIM) and two dimensional beam propagation method(2D-BPM),the structure parameters are optimized and the fabrication tolerances are *** results indicate that the performance of the coupler is deeply affected by the coupler's width,etching depth and photolithography alignment error in perpendicular direction.