数字签名面临的技术问题

数字签名技术将使我们的生活发生根本改变,但目前还存在许多问题,本文从PKI的建设、便利性、认证技术及非常规数字签名等角度探讨推广数字签名所必须面对的技术问题。     

Synthesis,Structure and Photoluminescence Properties of Mixed-Valent Trinuclear Copper Complex Assembled from Bis(<Emphasis Type="Italic">N</Emphasis>-imidazolyl)methane

In this work, [Cu₃I₂(PPh₃)₆(L₁)₂]∙2DMSO∙Cl₂ (1) (L₁ = bis(N-imidazolyl)methane) complex was synthesized by solvothermal method. The crystal and complexes were characterized by X-ray diffraction (XRD) analysis, Fourier Transform infrared (FTIR) spectroscopy, elemental analysis and photoluminescence (PL) measurements. XRD and FTIR analysis indicated that the complex 1 is a trinuclear compound, in the compound there are two kinds of copper atoms, i.e. monovalent, and divalent copper cations. For the copper(I) center, it is surrounded by two P, one N, and one iodide atoms to complete its tetrahedron geometry. While the copper(II) center is surrounded by two P and two nitrogen atoms, the chloride anions existed as free counter anions. The copper(II) atom and the copper(I) atoms were bridged by exobidentate L₁ ligand. The PL spectrum showed that the complex displays intense blue emission related to shallow holes.     

减少起重机吊具摆动的起升钢丝绳缠绕方式

介绍了一种新型的防摆的钢丝绳交叉缠绕方式，采用此方式的起重机可以减小厂房高度，降低厂房和起重机造价。     

Nanocellulose Composites—Properties and Applications

Nanocellulose composites combine the advantages of nanocellulose and composites. Recently, nanocellulose composites have been received more attentions due to their improved properties and promising broad applications. In the past, rapid progress has been made in the synthesis, properties, and mechanism of nanocellulose composites and potential applications were reported. There are a few reports on the increasing applications of nanocellulose composites with focus on the biomedical field, environmental field, electrode and sensor applications. In this article, the recent development of nanocellulose composites was reviewed via some typical examples. In addition to the synthesis methods, improved properties and potential applications were discussed. The problems and future applications of nanocellulose composites were also suggested.     

A unified algorithm for mobility load balancing in 3GPP LTE multi-cell networks

3GPP long term evolution (LTE) is a promising candidate for the next-generation wireless network, which is expected to achieve high spectrum efficiency by using advanced physical layer techniques and flat network structures. However, the LTE network still faces the problem of load imbalance as in GSM/WCDMA networks, and this may cause significant deterioration of system performance. To deal with this problem, mobility load balancing (MLB) has been proposed as an important use case in 3GPP self-organizing network (SON), in which the serving cell of a user can be selected to achieve load balancing rather than act as the cell with the maximum received power. Furthermore, the LTE network aims to serve users with different quality-of-service (QoS) requirements, and the network-wide objective function for load balancing is distinct for different kinds of users. Thus, in this paper, a unified algorithm is proposed for MLB in the LTE network. The load balancing problem is first formulated as an optimization problem with the optimizing variables being cell-user connections. Then the complexity and overhead of the optimal solution is analyzed and a practical and distributed algorithm is given. After that, the proposed algorithm is evaluated for users with different kinds of QoS requirements, i.e., guaranteed bit rate (GBR) users with the objective function of load balance index and non-GBR (nGBR) users with the objective function of total utility, respectively. Simulation results show that the proposed algorithm leads to significantly balanced load distribution for GBR users to decrease the new call blocking rate, and for nGBR users to improve the cell-edge throughput at the cost of only slight deterioration of total throughput.     

Lifetime maximization routing with network coding in wireless multihop networks

In this paper, we consider the lifetime maximization routing with network coding in wireless mul- tihop networks. We first show that lifetime maximization with network coding is different from pure routing, throughput maximization with network coding and energy minimization with network coding. Then we formulate lifetime maximization problems in three different cases of (i) no network coding, (ii) two-way network coding, and (iii) overhearing network coding. To solve these problems, we use flow augmenting routing (FA) for the first case, and then extend the FA with network coding (FANC) by using energy minimized one-hop network coding. After that, we investigate the influence of parameters of FANC, evaluate the performance of FANC with two-way and overhearing network coding schemes and compare it with that without network coding under two different power control models, namely, protocol and physical ones. The results show that the lifetime can be improved significantly by using network coding, and the performance gain of network coding decreases with the increase of flow asymmetry and the power control ability.     

Velocity forecasts using a combined deep learning model in hybrid electric vehicles with V2V and V2I communication

Vehicle velocity forecast is an important clue in improving the performance of energy management in hybrid electric vehicles(HEV). This paper presents a new combined model for predicting vehicle's velocity time series. The main features of the model are to combine the feature extraction capability of deep restricted Boltzmann machines(DBM) and sequence pattern predicting capability of bidirectional long short-term memory(BLSTM). Hence, the model is named as DBMBLSTM. In addition, the DRMBLSTM model utilizes the vehicle driving information and roadside infrastructure information provided respectively through vehicle-to-vehicle(V2V) and vehicle-to-infrastructure(V2I) communication channels to predict vehicle velocity at various length of prediction horizon. Furthermore, the predictions results of this study are compared with the state of the art of vehicle velocity forecasts. The root mean square error(RMSE) is used as an evaluation criteria of predictions accuracy. Finally,these compared prediction model are applied in model predictive control(MPC) energy management strategy for the verifications of fuel economy improvement of a HEV. Simulation results confirm that the proposed combined deep learning model performs better than other five prediction methods. Therefore, it is a means of arriving at a reliable forecast model for HEV.     

ANSYS在高功率横流CO2激光器流道温度场分析中的应用

本文采用有限元方法建立了高功率横流CO2激光器流道温度场数学模型,利用ANSYS再现了激光器稳定工作状态下流道温度场分布,提供了测定流道内部温度的新途径。     

Analysis and side peaks identification of Chinese DTTB signal ambiguity functions for passive radar

Passive radar is one of the current research focuses. The implementation of the Chinese standard digital television terrestrial broadcasting (DTTB) creates a new opportunity for passive radar. DTTB system contains single-carrier and multicarrier application modes. In this paper, ambiguity functions of the DTTB signals in the single-carrier and multicarrier application modes are analyzed. Ambiguity function of the DTTB signal contains one main peak and many side peaks. The relative positions and amplitudes of the side peaks are derived and the reasons for the occurrence of the side peaks are obtained. The side peaks identification (SPI) algorithm is proposed for avoiding the false alarms caused by the side peaks. Experimental results show that the SPI algorithm can indentify all the side peaks without the power loss. This research provides the foundation for designing the DTTB based passive radar. Supported by the National Natural Science Foundation of China (Grant No. 60232010), the Ministerial Foundation of China (Grant No. A2220060039) and the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No. 60625104)     

负载电阻及其对称性对光位敏器线性及精度的影响

通过对一维光位敏器（PSD）等效电路的分析,得出与具体系统无关的光位移普遍表达式。该式表明,负载电阻对于PSD内阻的比值及两边负载电阻的不对称性将极大地影响测量的线性及精确度,而PSD内阻随光源光强有数量级的变化,因此一般的光位移公式在用强光源（如激光）时应加以修正。