CrN/ZrN纳米多层膜的合成及其结构和性能的研究

利用非平衡直流磁控双靶溅射在不同的基底转速(4～11r/min)和不同反应气体流量下制备一系列的具有纳米周期的CrN/ZrN多层膜.利用X射线衍射,俄歇电子能谱,X射线光电子能谱表征了薄膜的成分和结构,利用纳米力学测试系统以及摩擦磨损仪测量了薄膜的机械性能和摩擦磨损性能,分析了基底的转速、反应气体的种类及流量对薄膜结构与机械性能和摩擦磨损性能的影响.结果表明在氮中混入适量氨气条件下合成的具有小纳米周期的多层膜,其硬度可达32 GPa,磨损率可低到0.3865×10-5mm3/Nm,明显优于单质薄膜.低角度XRD分析证明了薄膜的多层结构.     

1-苄基-4-(5,6-二甲氧基-1-茚酮-2-亚甲基)-吡啶的合成及动力学研究

以5,6-二甲氧基-2-(4-吡啶基)-亚甲基-1-茚酮(Ⅱ)和溴化苄(Ⅲ)为原料,合成盐酸多奈哌齐的关键中间体1-苄基-4-(5,6-二甲氧基-1-茚酮-2-亚甲基)-吡啶(Ⅰ).研究了主要因素对反应的影响,n(Ⅱ)∶n(Ⅲ)=1∶1.3,反应时间60 m in,收率为92.8%.经核磁共振谱图分析确认为目标产物.进一步讨论了反应的动力学过程,并建立了动力学方程.     

Durability of FRP Composite Bridge Deck Materials under Freeze-Thaw and Low Temperature Conditions

Fiber-reinforced polymer (FRP) composites, especially lightweight sandwich structures, are rapidly finding their way into civil infrastructure application. FRP composite panels are particularly attractive as bridge deck systems due to their high strength, low density, and durability, which are of importance to the bridge industry. Most of the vast amount of durability data for FRP has been generated for aerospace and automotive applications, which involve very different service conditions than civil infrastructure. For civil engineering applications, it is essential to examine the durability performance of FRP materials under weathering conditions. The ultimate goal of this research is to develop a reliable framework for durability assessment of FRP decks, including laboratory testing procedure and finite-element simulation capability. Such a framework should be applicable to all types of FRP deck construction. In this paper, specimens of typical FRP bridge deck skin materials are subjected to freeze-thaw cycling between 4.4 and ?17.8°C in media of dry air, distilled water, and saltwater, and constant freeze at ?17.8°C . The selected deck is used as an example for demonstration purposes. In addition, selected specimens are subjected to simultaneous environmental exposure conditions and sustained loading of 25% ultimate strain. It should be emphasized that most of the environmental conditions reported in the literature produce minor deterioration of a single composite property, and the assessment of such effect on this single property becomes unreliable because of a large property variation. Therefore, in this paper we use multiple mechanical properties as performance indices for damage evaluation. Based on findings from this work, it is concluded that freeze-thaw cycling between 4.4 and ?17.8°C alone and up to 1,250 h and 625 cycles caused very insignificant or no change in the flexural strength, storage modulus, and loss factor of the FRP specimens conditioned in dry air, distilled water, and saltwater. Small reductions in storage modulus (about 1% or less) were observed when specimens were prestrained and subjected to 250 freeze-thaw cycles in distilled water and saltwater. Changes in flexural strength were statistically insignificant, since they were within the data scatter.     

梅山铁矿磷的赋存特征及降磷途径

采用化学分析、光学显微镜、电子探针等手段研究表明，梅山铁矿石中的磷是以磷灰石独立矿物形式存在的。对磷灰石在矿石中的嵌布特点、解离性，及其在选矿过程中的走向进行了详细研究。根据研究结果提出了该矿铁精矿脱磷的合理途径。     

克隆遗传算法与模拟退火算法相结合的配电网络重构

配电网重构可以提高配电网运行的安全性、经济性和供电质量,对于当前国内配电自动化系统建设和应用具有重要意义。将克隆遗传算法(CGA)与退火算法(SA)结合起来,把退火算法中的Metropolis抽样准则融入到克隆遗传算法中,形成克隆遗传退火算法(CGSA)。以网损最小为目标函数,以配电网电压降的限制、线路电流量的限制等为约束条件,在考虑配电网自身特点的基础上,以IEEE33节点为算例,利用克隆遗传退火算法求解。结果证明该优化算法具有较好的全局收敛性和收敛速度。     

An Equivalence between SILF-SVR and Ordinary Kriging

Support vector regression (SVR) is a powerful learning technique in the framework of statistical learning theory, while Kriging is a well-entrenched prediction method traditionally used in the spatial statistics field. However, the two techniques share the same framework of reproducing kernel Hilbert space. In this paper, we first review the formulations of SILF-SVR where soft insensitive loss function is utilized and ordinary Kriging, and then prove the equivalence between the two techniques under the assumption that the kernel function is substituted by covariance function.     

Continuous-Time Negotiation Mechanism for Software Agents

While there are several existing mechanisms and systems addressing the crucial and difficult issues of automated one-to-many negotiation, this paper develops a flexible one-to-many negotiation mechanism for software agents. Unlike the existing general one-to-many negotiation mechanism, in which an agent should wait until it has received proposals from all its trading partners before generating counterproposals, in the flexible one-to-many negotiation mechanism, an agent can make a proposal in a flexible way during negotiation, i.e., negotiation is conducted in continuous time. To decide when to make a proposal, two strategies based on fixed waiting time and a fixed waiting ratio is proposed. Results from a series of experiments suggest that, guided by the two strategies for deciding when to make a proposal, the flexible negotiation mechanism achieved more favorable trading outcomes as compared with the general one-to-many negotiation mechanism. To determine the amount of concession, negotiation agents are guided by four mathematical functions based on factors such as time, trading partners' strategies, negotiation situations of other threads, and competition. Experimental results show that agents guided by the four functions react to changing market situations by making prudent and appropriate rates of concession and achieve generally favorable negotiation outcomes     

Student Perceptions of Asynchronous Computer-Mediated Communication in Face-to-Face Courses

While there are many distance education studies of student satisfaction or perceptions of CMC, studies on residential student perceptions of CMC are rare. A paper survey was administered to 105 residential graduate and undergraduate students at a midwestern U.S. university. Results indicated that the majority of students preferred face-to-face discussion over CMC for most tasks; however, CMC was preferred overall for simple learning tasks. Content analyses of student responses to open-ended questions revealed that some students perceived face-to-face discussion to be faster, easier, and more convenient, while others perceived that CMC saves time and is more convenient. A discriminant analysis revealed several important factors that predicted those who preferred CMC for discussion. Students further commented that they would learn better from CMC if their instructors were more involved with and enthusiastic about CMC. Speed and convenience appear to be more important to students than whether discussion is face-to-face or CMC .     

不确定性表示及在高性能鲁棒飞行控制器设计中的应用研究

针对采用H∞鲁棒控制方法设计出的控制器一般较为保守的问题，分析得到主要原因是对象不确定的描述方式过于保守，限制了系统性能指标的提高，通过对不确定性产生的物理机理分析，给出了一种基于对象物理方程分析的保守性较小的不确定描述方法。研究表明，对于不确定性认识清楚，数学描述恰当给控制问题求解带来很大方便，以某型号飞机的大包线姿态角度控制为算例，采用鲁棒混合灵敏度方法设计控制器，由于不确定的描述保守性较小，系统不仅在大包线范围内具有鲁棒稳定性，而且具有鲁棒性能。     

CPDLC交互通信人机界面设计研究

CPDLC（Controller Pilot Data Link Communication)是数据链技术在现代空中交通控制的应用之一。通过分析飞行任务的特殊性，说明人机界面设计是其实际应用的关键。从对RTCA DO219指令集的分析出发，对指令进行重新分类整理，设计综合人机界面显示单元，实现飞行员和控制台之间方便快速的对话磋商，并进行了仿真设计。