发达国家食品召回机制给我们的启示

建立健全食品安全召回机制,已成为许多国家食品安全监督管理的新型理念、重要手段和发展趋势.对美国、加拿大、澳大利亚、新西兰、欧盟等发达国家和地区在食品召回的法律保障、职责分工、召回程序、信息系统等方面的主要特点进行分析和总结,就我国在食品安全召回的法律体系、机构设置、技术支撑、实施过程、应急措施等方面的现状和存在的问题进行对比研究,并就建立和完善我国食品召回机制提出了完善法律法规体系、加强技术支撑建设、明确管理协调机构、建立完备溯源体系、加强教育宣传培训、完善应急处理体系等建议和对策.     

Damage and deterioration mechanism and curing technique of concrete structure in main coal cleaning plants

Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Da-tun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian mine of the Xuzhou Mining Group Co. Ltd. In these projects, the operating environment and reliability of concrete structures in the main plants of the three companies were investigated and the safety of the structures inspected. Qualitative and quantitative analyses were made on the spe-cial natural, technological and mechanical environments around the structures. On the basis of these analyses, we discuss the long-term, combined actions of the harsh natural (corrosive gases, liquids and solids) and mechanical environments on concrete structures and further investigated the damage and deteriorating mechanisms and curing techniques of concrete structures in the main coal cleaning plants. Our study can provide a theoretical basis for ensuring the reliability of concrete structures in main coal cleaning plants.     

创业型小企业电子商务协调机制的研究——以西安“通讯盒子”公司为例

通过对创业型小企业如何在电子商务活动中建立各成员间协调机制的研究,结合对西安"通讯盒子"有限公司电子商务协调机制的剖析,提出创业型小企业电子商务活动应重点夯实协作与诚信两大基础协调机制。     

Behavioral and electrophysiological study of antifeedant mechanisms associated with polyhydroxy alkaloids

Eleven polyhydroxy alkaloids of plant origin were tested for anti-feedant effects against larvae of the lepidopteransSpodoptera littoralis, Spodoptera frugiperda, Heliothis virescens, andHelicoverpa armigera. Data from behavioral and electrophysiological investigations were correlated to reveal information on the mode of action of the antifeedants. The pyrrolidine DMDP was an effective antifeedant for all four species, whereas the piperidines fagomine and XZ-1 and the pyrrolizidine alexine were all ineffective as antifeedants. The activity of the pyrrolidines CYB-3 and DAB-1, the piperidines DNJ, DMJ, and BR1, and the bicyclic octahydroindolizine castanospermine varied among species. The investigation focuses on the structural similarities between some of the alkaloids and some common phagostimulatory sugars and illustrates a neural interaction involving the neurons that are differentially responsive to alkaloids and sugars. InS. littoralis, the neurons responding specifically to the alkaloids DMDP, DAB-1, and castanospermine and to the sugars fructose, sucrose, and glucose are more active when the compounds are applied singly than when an alkaloid and a sugar are applied together. The implications for the occurrence and functioning of different sugar receptor sites are discussed.     

基于债务的机会网络"物-物交换"激励机制

针对机会网络简单"物-物交换"(SBT)激励机制降低网络性能的问题,设计了一种基于债务的"物-物交换"(DBT)激励机制.DBT通过引入债务关系改变了SBT中严格的等价交换原则,增加了单次交易的转发数据量,从而提高了网络性能.为使债务关系可靠运行,设计了基于信任的惩罚机制和基于债务的缓存策略.仿真实验证明,和SBT相比,DBT在有效激励节点协作的同时提高了网络性能.     

基于多层注意力机制—柔性AC算法的机器人路径规划

针对行动者—评论家（AC）算法存在的经验学习样本维度高、策略梯度模型鲁棒性低等问题,依据多代理系统的信息协作优势,构建注意力机制网络并作为代理体,引入多层并行注意力机制网络模型对AC算法进行改进,提出一种基于多层并行注意力机制的柔性AC算法。将其用于解决动态未知环境下的机器人路径规划问题,可增强行动者的策略梯度鲁棒性并降低评论家的回归误差,实现机器人路径规划最优方案的快速收敛。实验结果表明,该算法有效克服机器人路径规划的局部最优,具有计算速度快、稳定收敛的优点。     

运动副间隙对多杆锁机构动力学特性的影响

为降低因受力异常而出现飞机货舱门意外打开的概率,详细研究运动副间隙对多杆锁机构动力学特性的影响．采用无质量的等效间隙杆描述运动副的间隙,以拉格朗日动力学方程和螺旋理论为基础建立了多杆锁机构的动力学分析模型,并用MATLAB软件编程对模型进行了求解分析．结果表明: 杆的角速度、角加速度、驱动力矩和铰链约束力对运动副间隙的大小比较敏感,在奇异位型附近受到的影响最大．间隙为10 μm时,其对多杆锁机构的动力学影响较小;间隙为100 μm时,其对多杆锁机构的动力学影响明显增强．     

推进生态文明建设,建立环境污染损害鉴定评估机制

面对日益严重的环境问题,胡锦涛在十八大报告中提出要加强生态文明制度建设,要健全生态环境保护责任追究制度和环境损害赔偿制度。然而作为环境保护责任追究制度和环境损害赔偿制度基础的环境污染损害鉴定评估机制不论是在理论还是在立法、司法以及执法方面在我国均属空白。本文在生态文明视野下,总结了环境污染损害鉴定评估机制建立的意义以及建立过程中可能存在的问题,对于提高人们建立鉴定评估机制的意识有帮助,然而具体落实到实践活动这一过程还有待接下来的研究。     

Creep behavior and failure mechanisms of CVI and PIP SiC/SiC composites at temperatures to 1650 °C in air

Creep properties of 2D woven CVI and PIP SiC/SiC composites with Sylramic™-iBN SiC fibers were measured at temperatures to 1650 °C in air and the data was compared with the literature. Batch-to-batch variations in the tensile and creep properties, and thermal treatment effects on creep, creep parameters, damage mechanisms, and failure modes for these composites were studied. Under the test conditions, the CVI SiC/SiC composites exhibited both matrix and fiber-dominated creep depending on stress, whereas the PIP SiC/SiC composites displayed only fiber-dominated creep. Creep durability in both composite systems is controlled by the most creep resistant phase as well as oxidation of the fibers via cracking matrix. Specimen-to- specimen variations in porosity and stress raisers caused significant differences in creep behavior and durability. The Larson-Miller parameter and Monkman-Grant relationship were used wherever applicable for analyzing and predicting creep durability.     

Application of High Temperature Corrosion-Resistant Materials and Coatings Under Severe Corrosive Environment in Waste-to-Energy Boilers

Corrosion-resistant materials (CRMs) and coatings are key technologies to increase power generation efficiency and reduce maintenance in waste-to-energy (WTE) plants. Corrosion environment became severe as steam temperatures have increased. The steam condition of more than 400 °C/3.9 MPa became possible in WTE boilers by using highly durable corrosion-resistant coatings, such as thermal spray of Al/80Ni20Cr alloy, HVOF-sprayed NiCrSiB alloy, Alloy 625 weld overlay for waterwall tubes and also superheater tubes. Also, the use of 310S type stainless steels and high Cr-high Mo-Ni base and high Si-Cr-Ni-Fe alloys have progressed because of a better understanding of corrosion mechanisms. Furthermore, high durability coatings using cermet and ceramic materials were applied to high temperature superheaters. This paper describes the major developments and the application of CRMs and coating technologies in the last 30 years in WTE plants, the corrosion mechanisms of alloys, the deterioration mechanisms of spray coating layers, and future subjects for the development of corrosion-resistant materials and coatings.