Controlled Secure Direct Communication Protocol via the Three-Qubit Partially Entangled Set of States

In this paper, we first re-examine the previous protocol of controlled quantum secure direct communication of Zhang et al.’s scheme, which was found insecure under two kinds of attacks, fake entangled particles attack and disentanglement attack. Then, by changing the party of the preparation of cluster states and using unitary operations, we present an improved protocol which can avoid these two kinds of attacks. Moreover, the protocol is proposed using the three-qubit partially entangled set of states. It is more efficient by only using three particles rather than four or even more to transmit one bit secret information. Given our using state is much easier to prepare for multiqubit states and our protocol needs less measurement resource, it makes this protocol more convenient from an applied point of view.     

高性能通用DSP寄存器扩展设计实现方法

本文提出一种高性能通用DSP扩展寄存器的设计及实现方法,该方法是我国自主研发的高性能通用DSP中实现寄存器堆扩展的一种新方法,其优点是在不影响现有指令集及指令机器码位宽的前提下,实现对处理器内部寄存器堆的成比例扩展。通过在我国自主研制DSP上的实际应用,证明了该扩展方法的有效性和实用性。     

高效的量子密钥分配协议

为提高量子密钥分配协议的密钥生成率, 构造了一组两方三级系统的完备正交归一化基. 利用该正交归一化基和交换粒子之间的纠缠提出了一种量子密钥分配协议. 三级可以推广到多级,利用粒子之间的纠缠交换和多级密钥分配可以极大地提高检测窃听的效率、密钥生成率以及信息容量.     

德国土木工程教育的发展趋势及启示

本文主要介绍了德国土木工程教育的现状、发展趋势和教学特点 ,结合我国土木工程教育实践 ,构建了我国土木工程师的类型 ,并提出几点启示     

电动汽车换电站时序响应能力模型与充电计划制订策略

由于蓄电池具有良好的储能特性以及可控性,电动汽车换电站运营商在满足换电需求的前提下,可以响应电网企业的激励措施,达到系统运行的要求。首先,根据换电站内电池组的状态参量,建立电池组的状态矩阵;其次,将电池组进行状态分群,对其中处于可控状态的电池组实施控制;最后,运用递推的思想研究该换电站内备用电池组的可控负荷裕度带,进而指导换电站运营商根据电网企业的运行目标制订相应的充电计划,达到负荷平衡、改善区域负荷特性等目的。     

交直流混合微电网中电动汽车充换电系统研究

在电动汽车技术飞速发展和大力倡导节能减排形势下,如何提高电动汽车充换电效率成为研究热点之一。设计了交直流混合微电网电动汽车充换电能量管理系统和双向DC/DC变换器控制策略,并将电动汽车充换电装置与混合微电网储能装置进行有机结合,旨在提高设备利用率和降低系统成本。仿真实验与算例分析结果表明,系统不仅有削峰填谷、节能减排和降低成本效果,也对电动汽车进一步发展有一定的促进作用。     

基于GHZ态纠缠交换的量子确定性密钥分发方案

为了提高确定性密钥分发效率,提出了基于GHZ态纠缠交换的量子确定性密钥分发(Quantum deterministic key distribution,QDKD)方案,方案充分利用量子力学纠缠交换的原理,通信双方通过共享一对GHZ粒子态,在纠缠、测量操作后接收者Bob可根据发送者Alice发送的经典信息推断出确定密钥,该协议与其他基于GHZ纠缠态的QDKD方案不同之处在于,使用的两个GHZ粒子态制备操作且粒子分发操作由Bob完成,安全分析表明窃听者的窃听行为会被及时发现。所提出的方案是高效的,除去用于窃听检测的粒子,所剩的粒子全部用于信息传输,能够达到60%的密钥分发效率,且方案可操作性强.     

巧用复合循环指令数控车削复杂零件

生产加工时,经常遇到一些零件形状复杂、加工难度大、精度要求高的情况,运用传统的加工方法无法实现零件的要求。通过在数控车床编程过程中巧妙使用一些复合循环指令加工这些零件,简化编程的复杂程度,提高工作效率,从而更好地完成零件的加工。     

The impact of two different think-aloud instructions in a usability test: a case of just following orders?

The instructions used in think-aloud studies can range from a simple request to think-aloud, to an explicit instruction to include certain types of content. The present study compared two think-aloud instructions: the classic neutral think-aloud instruction and an explicit instruction requesting explanations and content that is relevant to the user experience. Data from task performance, mental workload, think-aloud protocols and usability problems were collected from 16 participants, equally distributed between the two think-aloud instruction conditions. No differences were found in task performance, however, participants in the explicit instruction condition reported higher mental workload and a focus on finding interface problems. The explicit instruction condition also yielded more utterances about the user experience, expectations and explanations of behaviour than the neutral condition. An analysis of the resultant usability problems revealed that the explicit instruction led to a larger number of dialogue, navigation, layout and functionality problems, but that the problems which were unique to this condition were, in the main, at a low level of severity.     

Supporting driver headway choice: The effects of discrete headway feedback when following headway instructions

With specific headway instructions drivers are not able to attain the exact headways as instructed. In this study, the effects of discrete headway feedback (and the direction of headway adjustment) on headway accuracy for drivers carrying out time headway instructions were assessed experimentally. Two groups of each 10 participants (one receiving headway feedback; one control) carried out headway instructions in a driving simulator; increasing and decreasing their headway to a target headway of 2 s at speeds of 50, 80, and 100 km/h. The difference between the instructed and chosen headway was a measure for headway accuracy. The feedback group heard a sound signal at the moment that they crossed the distance of the instructed headway. Unsupported participants showed no significant difference in headway accuracy when increasing or decreasing headways. Discrete headway feedback had varying effects on headway choice accuracy. When participants decreased their headway, feedback led to higher accuracy. When increasing their headway, feedback led to a lower accuracy, compared to no headway feedback. Support did not affect driver's performance in maintaining the chosen headway. The present results suggest that (a) in its current form discrete headway feedback is not sufficient to improve the overall accuracy of chosen headways when carrying out headway instructions; (b) the effect of discrete headway feedback depends on the direction of headway adjustment.