硫氰酸汞分光光度法测定空气颗粒物中的氯化氢

用硫氰酸汞分光光度法分别测定空气及空气颗粒物和空气中氯化氢的含量,利用相减法得出空气颗粒物中氯化氢的含量。线性范围为0～1．00μg/mL,线性回归方程为A=0．0799c 0．00124,相关系数为0.9995。该方法灵敏、简便,测定结果的相对标准偏差为6．8％(n=7),加标回收率为98．1％～103．9％。     

Reinforcement Learning-Based Multihop Relaying: A Decentralized Q-Learning Approach

Conventional optimization-based relay selection for multihop networks cannot resolve the conflict between performance and cost. The optimal selection policy is centralized and requires local channel state information (CSI) of all hops, leading to high computational complexity and signaling overhead. Other optimization-based decentralized policies cause non-negligible performance loss. In this paper, we exploit the benefits of reinforcement learning in relay selection for multihop clustered networks and aim to achieve high performance with limited costs. Multihop relay selection problem is modeled as Markov decision process (MDP) and solved by a decentralized Q-learning scheme with rectified update function. Simulation results show that this scheme achieves near-optimal average end-to-end (E2E) rate. Cost analysis reveals that it also reduces computation complexity and signaling overhead compared with the optimal scheme.     

Application of vibrational spectroscopy for the analysis of polymer composites

Various examples of filled elastomeric networks will illustrate the potential of Fourier-transform infrared spectroscopy for a better understanding of the properties of elastomeric composite materials which are two-phase materials. The addition of an inorganic component to polymers leads to improvements in various physical and mechanical properties. These improvements are the result of a complex interplay between the properties of the individual constituent phases : the polymer, the filler and the interfacial region. Infrared spectroscopy has been used to characterize the interface in the isotropic state and also under uniaxial extension.     

原位TiB晶须增强钛基复合材料的磨损机制

将自蔓延和熔模精铸方法相结合,制备了原位TiB晶须增强钛基复合材料;采用X射线衍射仪和扫描电子显微镜分析了复合材料的相组成和显微组织,结合磨损表面、磨屑形貌及剖面显微组织分析结果探讨了复合材料表面的磨损机制;采用销-盘式摩擦磨损试验机评价了复合材料的耐磨性能.结果表明:TiB晶须尺寸细小、长径比大、在基体中分布均匀;与基体合金相比,钛基复合材料的耐磨性能显著提高,这是由于TiB晶须具有增强作用和承载作用所致.     

Resonant Raman‐based cytochrome C biosensor as a tool for evaluating the oxidative properties of the diesel exhaust particulate matter

Air pollution mostly originating from car exhaust and industrial emissions is seriously endangering human health. The study of toxic effects of particulate matter (PM) is a subject of very active research that covers a broad field from biology to chemistry and technology. The main issue of these works is the understanding of the oxidative properties of PM. In this paper, we present a quantitative analytical method based on the resonance Raman spectroscopy of cytocrome c that can be used to monitor the oxidative reactions that may take place between biological samples and PM. Copyright © 2016 John Wiley & Sons, Ltd.     

钢筋混凝土柱二阶配筋的不同计算方法对比

计算钢筋混凝土柱的配筋,需要迭代求解材料非线性和几何非线性问题,不便实际应用。基于混凝土和钢筋的本构关系,根据截面应变求解精确的截面内力-曲率关系,简化杆件变形曲线为二次抛物线来计算外部作用。根据精确的截面内力-曲率曲线和外部作用曲线的特点,分别按照我国《混凝土结构设计规范》(GB 50010-2010)和欧洲规范(Eurocode 2),对截面的极限曲率进行了简化,最后绘制了计算杆件二阶总弯矩和配筋的总诺模图。通过具体算例对比分析,结果显示欧洲规范的简化与精确值更相符,且更经济。     

Morphology and Properties of Particulate Filled Polymers

Although the structure of particulate filled polymers is usually thought to be very simple, often structure related phenomena determine their properties. Segregation occurs only when long flow paths and large particles are used in production. The occurrence and extent of aggregation depend on the relative magnitude of attractive and separating forces, which prevail during the homogenization of the composite; the balance of adhesive and shear forces determines structure. Fillers of small particle size always aggregate, usually leading to decreased strength and especially low impact resistance. Anisotropic particles (talc, mica, short fibers) are orientated during processing. ESR is a relatively simple technique for the estimation of orientation and orientation distribution, which are determined by processing conditions, i.e. flow pattern, shear conditions, mold filling rates, cooling conditions, etc. The orientation of the particles strongly affects composite stiffness and strength. In practice, often several factors simultaneously influence the properties of products prepared from particulate filled polymers. Separation of the effects of the influencing factors is difficult, although such knowledge would help to control composite properties. The structure and properties of injection and compression moulded PP composites containing CaCO₃ or talc differs considerably from each other. The aggregation of CaCO₃, the nucleating effect and the orientation of talc affect product properties. The latter are also influenced by the skin-core structure developing during injection molding as well as by the orientation of the polymer. An example is discussed in this paper, which facilitates the identification of the effect of these factors with the help of a simple model and indicates a way in which product properties can be controlled.     

Filler networks in elastomers

Elastomers are soft materials that can be reinforced by dispersing into them nanosized solid particles. Common examples of the latter are silica or carbon black aggregates. However, the mechanism of reinforcement is still not yet fully understood. Our work consists in investigating by small-angle X-ray scattering (SAXS) the structure of the aggregate network spreading throughout the matrix in the initial sample and its modification during and after straining (elongation). The goal is to relate the macroscopic mechanical behaviour with the structure of the aggregate network. The present paper is a qualitative overview of recent results obtained on well defined composites.     

Molecular Arrangements in Polymer‐Based Nanocomposites

Monte Carlo computer simulations have been performed for model polymers containing randomly distributed spherical filler particles of diameter 8 times the transverse diameter of the polymer chains. The partial volume of the filler has been varied from 10% to 50%. The polymer/filler interface is characterized by densely packed and ordered shells of polymer units of thickness nearly twice the diameter of the units. The chain dimensions in filled systems are always found to be slightly smaller than in the unfilled melt. The behavior of various parameters chosen such to characterize the molecular arrangements in polymer‐based nanocomposites is analyzed, leading to a general picture in which the chains are considered to be sequences of interface, bridge and loop segments. The relative abundance of segments of each type, their average length and the way they are allocated in sequence change with changing the partial volume of filler.