室温脉冲螺旋Wiggler磁体和大电流脉冲电源的研究

本文研究了适用于自由电子激光的室温脉冲螺旋Ｗｉｇｇｌｅｒ磁体，对其设计构思、磁场特性和设计参数进行了分析和计算．作者在文中还研究并设计了螺旋Ｗｉｇｇｌｅｒ磁体的大电流宽脉冲供电电源；分析了脉冲电流的时间特性对产生自由电子激光的影响程度．     

ID-based threshold decryption secure against adaptive chosen-ciphertext attack

This paper proposes an identity-based threshold decryption scheme IB-ThDec and reduces its security to the Bilinear Diffie-Hellman problem. Compared with previous work, this conceals two pairing computations in the ciphertext validity verification procedure. The formal proof of security of this scheme is provided in the random oracle model. Additionally, we show that IB-ThDec can be applied to the threshold key escrow and the mediated cryptosystems.     

人工智能在冷轧带肋钢筋工艺参数优化中的应用

论述了人工智能在冷轧带肋钢筋工艺参数优化中的应用,首先利用神经网络建立起冷轧带肋钢筋工艺参数与产品抗拉强度之间关系的数学模型,然后用遗传算法对工艺参数优化。按优化后的工艺参数在某拉丝加工厂进行了大批量生产试验,产品的合格率达到98%以上,从而为控制冷轧带肋钢筋工艺参数提供了一条行之有效的途径。     

Explaining similarity for SPARQL queries

World Wide Web - Knowledge graph has gained significant popularity in recent years. As one of the W3C standards, SPARQL has become the de facto standard query language to retrieve the desired data...     

Optimal controller location in wireless networked control systems

The control performance of wireless networked control systems (WNCS) has been shown to heavily depend on the packet delivery quality of both the sensor‐to‐controller and controller‐to‐actuator communications. Such quality relies on the relative distance between the wireless transmitter and receiver, which naturally raises the challenging problem of controller placement in WNCS for optimal control performance. In this paper, we investigate the optimal controller location (OCL) problem in WNCS based on linear‐quadratic‐Gaussian control strategy. For the one‐hop network case where the controller can only be placed at either the sensor side or the actuator side, we derive a simple yet effective criterion to determine the OCL. For the more general multi‐hop case where the controller can be located at either one of the sensors, relays, or actuators, we obtain the necessary and sufficient condition under which the closed‐loop system is guaranteed to be stable. On the basis of these results, we further transform the OCL problem into an optimization problem that can be solved efficiently. Numerical results are provided to verify our analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

3-D Unitary ESPRIT: Accurate attitude estimation for unmanned aerial vehicles with a hexagon-shaped ESPAR array

Accurate estimation of the attitude of unmanned aerial vehicles (UAVs) is crucial for their control and displacement. Errors in the attitude estimate may misuse the limited battery energy of UAVs or even cause an accident. For attitude estimation, proprioceptive sensors such as inertial measurement units (IMUs) are widely applied, but they are susceptible to inertial guidance error. With antenna arrays currently being installed in UAVs for communication with ground base stations, we can take advantage of the array structure in order to improve the estimates of IMUs via data fusion. In this paper, we therefore propose an attitude estimation system based on a hexagon-shaped 7-element electronically steerable parasitic antenna radiator (ESPAR) array. The ESPAR array is well-suited for installment in the UAVs with broad wings and short bodies. Our proposed solution returns an estimation for the pitch and roll based on the inter-element phase delay estimates of the line-of-sight path of the impinging signal over the antenna array. By exploiting the parallel and centrosymmetric structure in the hexagon-shaped ESPAR array, the 3-dimensional Unitary ESPRIT algorithm is applied for phase delay estimation to achieve high accuracy as well as computational efficiency. We devise an attitude estimation algorithm by exploiting the geometrical relationship between the UAV attitude and the estimated phase delays. An analytical closed-form expression of the attitude estimates is obtained by solving the established simultaneous nonlinear equations. Simulations results show the feasibility of our proposed solution for different signal-to-noise ratio levels as well as multipath scenarios.     

金沙江梯级水电站群联合发电运行三种常规调度方法研究

采用常规调度图、蓄能调度图和调度函数三种常规调度方法对金沙江中游梯级水电站群的联合发电运行进行分析、计算,在同一条件下对三种调度方法的模拟结果与发电量最大模型及保证出力最大模型的结果进行了对比。从不同侧面对这3种方法进行了分析比较,给出了较为客观的评价,为水电站寻找调度规律、拟定运行指导准则提供重要的参考价值,为未来中长期发电计划的制定提供可靠依据。     

BS-PT基高温压电超声换能器研究

针对高温超声检测技术的应用需求,该文研究了基于钪酸铋-钛酸铅(BS-PT)基高温压电陶瓷材料的高温超声换能器。利用PiezoCAD器件仿真软件设计并制作了一款1 MHz的高温压电超声换能器,且在200 ℃下对该器件的电学和声学性能进行了测试和分析。结果表明,随着测试温度的升高,换能器的脉冲回波幅值虽略有降低,但其中心频率、带宽变化不明显,带宽仍保持在20%左右。该文设计并制备的BS-PT基高温压电超声换能器可以在200 ℃环境中正常稳定工作。     

Efficient chosen-ciphertext secure certificateless threshold key encapsulation mechanism

As a practical extension of our previous work on certificateless threshold cryptosystem, this paper proposes the first direct certificateless threshold key encapsulation mechanism that inherits the same trust level of the original scheme and removes the length limitation of a traditional public key encryption. Security against threshold chosen-ciphertext attacks are proved in a random oracle model under a new assumption. It tolerates the Type I adversary that can replace public keys and the Type II adversary that has access to the system’s master key. The implied encapsulation scheme is very efficient when compared to the most efficient schemes in a traditional public key cryptosystem, and it is slightly more efficient in terms of key length and encapsulation speed when compared to the identity-based cryptosystems that have the same ciphertext overhead. Finally, we describe several potential modifications of our scheme.     

白口铸铁的磨料磨损行为及耐磨性

通过白口铸铁的耐磨试验，观察分析材料的磨面和磨屑；研究不同性能的白口铸铁在磨料磨损时的行为机理．