以写字本为例辨析Canvas绘图机制的优劣

通过比较SVG和Canvas两种绘图机制,辨析了使用Canvas在网页中绘图方案的优缺点。使用一个在线写字本案例,论述了Canvas捕获用户的鼠标事件根据用户输入来绘图的过程。最后总结了Canvas绘图的特性以及应用前景。     

基于Agent的网络教学系统设计

应用智能Agent技术,针对现有网络教学系统的弱点与不足,结合其原有的优点,进行了网络教学系统的设计。阐述了此系统的总体结构设计和系统设计,总体结构引用三层模型,包括用户层、中间通信层和服务层;在系统设计中给出了用户Agent设计、教学站点设计、移动Agent设计,构造了一个基于Agent技术的网络教学系统模型。     

基于工作流导向的“网络信息安全”实训教材建设

针对"网络信息安全"教材建设的现状进行分析,提出建设基于工作流导向的任务式实训模式教材的必要性,并从教材的指导思想、整体结构、内容结构及其特色等方面进行了阐述。实践证明,该新型教材的建设和使用能够激发学生学习网络安全知识的兴趣,提升动手能力,有效提高教学质量和效率。     

基于PHP的多功能域名销售管理系统设计

针对目前常用的域名销售系统存在的诸如在域名注册资料获取不便、域名闲置难以及时处理等问题,研究并实现了一套基于PHP语言的多功能域名销售管理系统。介绍了系统的体系结构与设计思路,对基于MySQL的数据库、各功能模块等进行了描述;通过使用Smarty的前台模板引擎,解决了对注册商的域名进行分类、多条件管理、编辑等问题。系统运行表明,该方法符合域名管理规范,能有效提高域名管理质量。     

Preparation of phenolic resin derived 3-D ordered macroporous carbon

Three-dimensionally ordered long-range macroporous carbon structures were prepared using commercially available phenolic resin by utilizing sacrificial colloidal silica crystalline arrays as templates that were subsequently removed by HF etching after pyrolysis in an argon atmosphere. SEM, TEM, and BET were employed to characterize the morphology and the surface area of the porous carbon structures. The pore size (150–1000 nm) and BET surface area, which reflect pore volume (298.6 m²/g (1.32 cm³/g) ∼ 93.7 m²/g (0.12 cm³/g)), of the macroporous carbon structures produced were approximately proportional to the size (150–1000 nm) of the sacrificial silica sphere templates used (annealing temp. 550°C). The achieved 550 nm porous carbon structures were examined to function as potential catalyst carriers and were successfully impregnated with Ag or Pt-Ru on their inner walls after borohydride reduction at room temperature. In addition, porous carbon patterns were fabricated using the ‘micromolding in capillary’ technique, which has potential applications in the microreaction technology.     

Deterministic transmission of an arbitrary single-photon polarization state through bit-flip error channel

We present two error-tolerance transmission protocols of a single-photon polarization state when bit-flip error is taken into account. For achieving the transmission target of the single-photon state, the first protocol needs to encode it to a nonmaximally entangled Bell state. Exploiting the interaction of the polarization entanglement with spatial entanglement between two photons, its success probability is 100 %. Different from the first protocol, the second one utilizes the idea of teleportation with an auxiliary Bell state. By performing quantum nondemolition measurement to analyze the parity, conventional measurement, and unitary transformation operations, the success probability of the second protocol is approximately unity. Furthermore, the second protocol can be generalized to the error-tolerance transmission of an arbitrary mixed state or the distribution of an arbitrary multi-photon entangled state.     

Relations between quantum correlations,purity and teleportation fidelity for the two-qubit Heisenberg XYZ system

Quantifying and understanding quantum correlations may give a direct reply for many issues regarding the interesting behaviors of quantum system. To explore the quantum correlations in quantum teleportation, we have used a two-qubit Heisenberg XYZ system with spin–orbit interaction as a quantum channel to teleport an unknown state. By using different measures and standard teleportation protocols, we have derived the analytical expressions for quantum discord, entanglement of formation, purity, and maximal teleportation fidelity of the system. We compare their different characteristics and analyze the relationships between these quantities.     

Finite-time control for discrete-time Markovian jump systems with deterministic switching and time-delay

In this paper, the finite-time control problem is investigated for a class of discrete-time Markovian jump systems (MJLSs) with deterministic switching and time-delay. The considered systems are subject to a piecewise-constant transition probability (TP) matrix, which leads to both the deterministic switches and stochastic jumps. First, the stochastic finite-time boundedness (SFTB) and l ₂ gain analysis for the systems are studied by employing the average dwell time (ADT) approach. Note that a finite-time weighted l ₂ gain is obtained to measure the disturbance attenuation level. Then, the mode-dependent and variation-dependent controller is designed such that the resulting closed-loop systems are stochastically finite-time bounded and have a guaranteed disturbance attenuation level. Finally, a numerical example is given to verify the potential of the developed results.     

Stochastic reliable control of a class of networked control systems with actuator faults and input saturation

The stochastic reliable control problem for networked control systems (NCSs) subject to actuator failure and input saturation is investigated in this paper. In order to get the relationship between the maximum allowable consecutive packet dropouts, the packet dropout probability, the actuator failure matrix and the input saturation, a packet dropout probability dependent condition is given via linear matrix inequality (LMI) technology. Then, a suitable reliable controller is designed to ensure the closed-loop system to be exponentially mean square stable against actuator failures and input saturation. Finally, numerical examples are provided to show the effectiveness of the proposed method.     

A formal framework for service mashups with dynamic service selection

The service mashup programming paradigm is a blooming faction of service oriented Architecture for developing web applications. A mashup application constructs its functionality by combining data, presentation and functionalities obtained from online services published by service providers such as Google and Amazon. This paradigm significantly facilitates the implementation of application and reduces the workload. But it also makes the application rely on the availability and qualities of the online services which beyond its control in which case the robustness of the system requires more concern. This paper proposes a formal model to specify and analyze the behavior and robustness of service mashups under a certain environment where some services may become unavailable. The specification contains both system specification and environment situation. Refinement theory are employed to specify the correctness of dynamic service selection. The framework realizes the service selection by allowing virtual service requests to be handled by any online service having consistent interface and refined functionality. The framework provides a clear definition of the robustness of mashup systems and proposes several rules as well as approaches to preserve the robustness during the development and maintenance of the system.