“平面支架”实验验证支架力学行为公式

为了验证支架弹性径向刚度公式和塑性极限压力公式的准确性,提出了“平面支架单元”的概念,并根据血管支架真实弯曲单元的结构,制作了相同结构的平面形式支架单元试件.利用MTS材料试验机对平面支架单元试件进行拉伸试验,将试件实验测量的压力-半径曲线与弹性径向刚度和塑性极限压力公式预测的压力曲线对比.结果显示,支架撑开的弹性阶段,实验测量的弹性径向刚度和公式计算的弹性径向刚度差值在3%以内,进入塑性阶段,实验得到的曲线与公式接近. 实验验证了这两个公式准确且精度较高.      

Robust password and smart card based authentication scheme with smart card revocation

User authentication scheme allows user and server to authenticate each other, and generates a session key for the subsequent communication. How to resist the password guessing attacks and smart card stolen attacks are two key problems for designing smart cart and password based user authentication scheme. In 2011, Li and Lee proposed a new smart cart and password based user authentication scheme with smart card revocation, and claimed that their scheme could be immunity to these attacks. In this paper, we show that Li and Lee＇s sctleme is vulnerable to off-line password guessing attack once the information stored in smart card is extracted, and it does not provide perfect forward secrecy. A robust user authentication scheme with smart card revocation is then proposed. We use a most popular and widely used formal verification tool ProVerif, which is based on applied pi calculus, to prove that the proposed scheme achieves security and authentication.     

综合客运枢纽交通技术要点分析

综合客运枢纽是综合交通运输体系的重要组织结点,交通组织和衔接是其发展和服务的核心,文章以徐州汽车北站为例,对综合客运枢纽交通组织原则和技术关键点进行探讨,以体现综合客运枢纽的＂无缝衔接＂和＂零换乘＂发展理念。     

Behavior-consistent service substitutions in dynamic environments

In this paper, a novel approach for service substitutions based on the service type in terms of its interface type and behavior semantics is proposed. In order to analyze and verify behavior-consistent service substitutions in dynamic environments, we first present a formal language to describe services from control-flow perspective, then introduce a type and effect system to infer conservative approximations of all possible behaviors of these services. The service behaviors are represented by concurrent behavior expressions （CBEs）. Built upon the interpretation of CBEs, behavior-consistent service substitutions are defined and analyzed by subtyping technology. The correctness of the analysis approach is guaranteed by type safety theorem, which is mechanically proved in the Coq proof assistant. Finally, applications in web services show that our method is effective and feasible.     

An enhanced safe distance car-following model

Gipps＇ model, a well-known safe distance car-following model, has a very strict restriction on the car-following behavior that the following vehicle has to maintain the exact safe distance to the leading vehicle to avoid rear crash. However, this restriction is not consistent with the real traffic condition. Due to that, an enhanced safe distance car-following model is proposed first, and then calibrated and evaluated using the field data. Furthermore, the simulation is conducted to analyze the characteristics of the new model. The results of evaluation and simulation illustrate that the proposed model has higher simulation accuracy than the original Gipps＇ model, and can reproduce the stable flow and shock wave phenomena that are very common in real traffic. Moreover, the simulation results also prove that the enhanced model can better stabilize the traffic flow than Gipps＇ model.     

Pragmatic physical layer abstraction method based on bit-LLR-wise exponential effective SNR mapping for bit interleaved coded orthogonal frequency division multiplexing system

In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing （BIC-OFDM） system from a parallel bit channel perspective. By combining the exponential effective SNR （signal-to-noise ratio） mapping （EESM） with the maximum a posteriori （MAP） algorithm, a bit LLR （log-likelihood ratio） wise EESM （BL-EESM） method is proposed. This method can abstract the link performance with high accuracy, especially for the case when channel estimation is imperfect. Afterward, the BL-EESM method is simplified by utilizing the non-linear quantization idea, which can reduce the times of exponential operation by two orders of magnitude at wide system bandwidth, yet shows little loss in accuracy. Our proposal can be applied to both system level simulations to save the time consumption and to practical terminals to facilitate the adaptive modulation and coding （AMC） procedure, bringing about throughput improvement at low hardware cost.     

Research on newly urbanized towns and districts in China

Since the last decade the central government endeavors to promote large scale of urbanization in China. Lots of new urban towns and districts are taking shape. Outline of the 12th Five-year Plan released by the central government points out that the new towns and districts are to be regulated. But few researches are considering the new towns and districts especially in the spatial distributive pattern and status in China. Given this situation this paper, after sorting out the world-wide research and development of new urban towns and districts, gives definitions of broad and narrow meanings. Based on the broad meaning definition, the database of new towns and districts in China is established. This paper then conducts a preliminary analysis of the new towns and districts. Then the two-step work plan and the advices are also proposed to further improve the research and practice of its kind in China.     

LM331在内燃机车检测中的应用

本文给出一种应用于内燃机车水阻测试台的主电压检测电路,该电路使用廉价的单片V/F转换器,通过光电耦合方式,既保证了检测电压的精度,又可有效防止各种干扰串入计算机控制系统。     

奥美拉唑治疗消化性溃疡临床疗效观察

本文采用非双盲法将80例活动性消化性溃疡患者随机分为两组,进行了对照治疗观察.Ⅰ组(奥美拉唑组)40例,20mg/d～40mg/d,疗程2周,愈合率为95%,Ⅱ组(雷尼替丁组)40例.300mg/d,疗程6周,愈合率为63%,两组差异非常显著(P<0.05)。结果显示,奥美位唑是一种高效抗各种消化性溃疡的药。     

我国铁路高速事业的发展

介绍了我国高速铁路的建设情况，同时也介绍了我国高速列车车辆的关键技术包括流线型，轻量化，制动系统，转向架系统，安全技术及车体材料等。