别点了品牌的“死穴”

几年前.红桃K以其“补血快”的品牌诉求,首先迅速占领了农村市场,实现了农村包围城市的品牌战略。但它做梦也没有想到的是.在它之后.一个以“功效持久”定位的补血新品——血尔.向品牌老大红桃K发难.并以迅雷不及掩耳之势.占领了大半个江山。的确.补血快.如果功效太短.有什么用呢?所以.对于“血尔”来说.让红桃K赖以成名的:“补血快”的品牌定位.成了一个让人隐痛的“死穴”。血尔在借用了红桃K的“快”的资源的基础上.提出了“功效持久”.得到了更多消费者的认同。     

反应磁控溅射研究进展

本文综述了反应磁控溅射技术的发展状态.分析了迟滞效应以及消除该效应的方法.这些方法.采用单极或双极脉冲技术可以有效的削除孤光现象.最后展望了反应磁控溅射的发展趋势.     

受控热核聚变装置中的真空测量技术——抗干扰快速规性能研究

受控热核聚变和等离子体物理研究装置中的真空测量是一种特殊环境下的真空测量.简要介绍了真空测量在等离子体容器中的应用和意义.对这种特殊环境进行了描述.并对如何解决这些复杂环境中正确可靠地测量压力(密度)提出了意见.等离子体物理研究装置中存在着很强的磁场和各种带电粒子、快速中性粒子、中子,高能光子等的强烈干扰.要正确、可靠地测量容器中的压力(密度).必须研究抗干扰测量技术.此外、装置中气体状态处于非平衡气流条件下.被测的气体分子既是空间位置的函数.也是空间方位的函数.容器中气流瞬变.要求测量必须快速.介绍了已研制成功的快速抗干扰真空规.这种规采用了几何屏蔽和脉冲调制抗干扰技术并利用了环境中的磁场强度.进一步提高了抗干扰能力.这种规还在入口采用威尼斯平行叶片百叶窗的结构和纵横交叉的电场屏蔽,保证了入口的气体流导,既解决了快速测量问题,又解决了抗干扰的要求.     

极高真空测量坐标系

极高真空测量指的是低于10~(-9)帕范围内的压力测量。首先介绍了最有希望解决10~(-11)～10~(-13)帕测量难题的电离规的测量下限所受到的四个限制因素.在第二部分综述了极高真空的测量技术.先对迄今为止所研究的极高真空测量技术进行归纳和分类.然后重点介绍了对热阴极电离规的收集极的改进情况.热阴极电离规中.对收集极的研究是进行得最多.也最有成效的一个方面.分析了7种改进方法.最后介绍了阴极和阳极的改进情况.第三部分建立了极高真空测量坐标系.三个坐标轴分别表示离子收集极、阳极技术、阴极技术.每一项具体技术也是对应于坐标轴上的元素.并用数字待号来表示.利用这个坐标系可以对极高真空测量技术有一个全面的总体认识.从而方便地分析各种技术之间的联系.然后对如何应用这个坐标系进行了应用举例.文末列出了有关的参考文献20篇.     

自动PCB外观检测仪中的图像采集研究

为了增强对PCB板检测的准确性和有效性,研制了自动外观检测仪.文章介绍了外观检测仪中图像实时采集和传输的实现.主要讨论了系统设计、检测和驱动开发.采用ALTERA公司的新型CYCLONE FPGA系列简化本地逻辑,大大缩短了硬件开发周期.工具DriverStudio的使用降低了驱动开发的难度.桥芯片PEX8111的使用和DMA传输方式的设计满足了高速、实时、准确的图像采集要求.     

孤北热电厂75 m高冷却塔爆破拆除

介绍了冷却塔控制爆破拆除实例,其中包括爆破方案的设计、预处理措施、爆破缺口、爆破参数的选取确定.以及安全验算和爆破安全技术措施等.在此次冷却塔爆破中.运用了各种大型机械设备来预处理部分塔壁,优化了爆破缺口,减少了爆破面积.通过合理设计和处理,不仅成功地实施了爆破,而且做到了充分解体.缩短了工期,节约了成本.     

氢化物——原子荧光法测定人发、血清中的硒

本文应用氢化物-原子荧光法测定了人发、血清中硒含量,研究了酸介质、酸度和共存元素的影响.同时研究了消除铜干扰的方法,获得了满意的结果.本方法的检出限为0.5ng/mL.回收率为98～102%.方法的重复性为4%.     

Mg-Zn系合金G.P.区和时效强化的研究进展

评述了国内外Mg-Zn系合金的研究进展.总结了Mg-Zn系合金中时效析出行为和各析出强化相的特征,通过分析铝合金G.P.区的形成规律,探讨了Mg-Zn系合金G.P.区的存在可能性.指出Mg-Zn系合金G.P.区的研究对Mg-Zn合金析出相变理论和发展高强度铗合金具有重要意义.     

饱和蒸汽压的测试线路

1984年为兰州西固石油站制作了一台经过改进的油脂饱和蒸汽压测定仪.主要在测量控制线路和温度控制方面作了较大改进.研制出了用晶体管线路代替电子管线路的测量线路.不仅仅在实验精度上,而且在体积和功耗上都优于1963年研制成功的真空油脂饱和蒸汽压测定仪.在第一部分,介绍了这台仪器的测量原理.没有采用悬摆法,而是采用蒸发速度法来测量油脂的饱和蒸汽压.蒸发速度法是先测出一组较高温度下的饱和油蒸汽的蒸发速度,然后推算任意温度下油的饱和蒸汽压的一种实验万法.第二部分介绍了测试装置.着重介绍了测量控制线路以及对邻苯二甲酸二丁脂的测试结果.并与1984年研制成功的微机测控油蒸汽压的实验结果作了比较.最后对实验结果进行了讨论和分析.     

水声遥控编码的误字率

本文从遥控编码系统的码元误码率的概念出发.给出了误码率与误字率之间的关系.导出了在多次重复发射下.计算码字漏报概率和虚警概率的计算方法.最后给出了几种不同编码方法的计算实例.     

Development of Catalytic Converters Using Detonation Spraying

One of the trends in hydrogen power engineering is the development of devices for the preparation of synthesis gas by the catalytic reforming of a hydrocarbon feedstock. Studies show the advantages of catalytic converters based on a modular catalyst support with a honeycomb-type structure produced from a metal foil, both sides of which are coated with highly porous oxide ceramics. The drawback of this design is a poor ability of the coating to withstand high-temperature operating conditions. The coating may detach from the substrate because of the difference in thermal expansion coefficients between the metal foil and the ceramic coating. Besides, a corrosion of metal foil takes place. The result of the present study is the development and application of a two-step coating method, which allows significantly increasing the service life of the catalyst supports. At the first step, a low-porosity ceramic layer is deposited on a metal foil by detonation spraying. At the second step, a high-porosity layer of a ceramic catalyst is deposited from suspension. In this work, the peculiarities of the detonation spraying of the ceramic coating on a metal foil and the design of the obtained catalytic converter have been addressed.     

Effects of shapes of electrodes on freezing of supercooled water in electric freeze control

In order to clarify the effects of electric charge on freezing of supercooled water, experiments were carried out. Two kinds of shapes were used for tips of electrodes. One was the sharp end surface. The other was the flat end surface. Aluminum was selected as the material. Water sample was kept in a test tube and cooled down at a constant cooling rate. When the water sample was maintained under a supercooling state, an electric charge was applied to the water sample with a small electric current. The degree of supercooling and the electric current were measured, continuously. Then the degree of supercooling at freezing was determined. It was found that the effects of electric charge were distinct according to the shapes of electrodes. The degree of supercooling at freezing was the lower in the case of flat end surface of the anode than that in the case of sharp end surface of the anode.     

Influence of surface roughness on the bonding quality in twin-roll cast clad strip

Manufacturing of aluminum-steel clad strips by means of twin-roll casting is of great interest due to a shorter production chain in comparison with convenient technologies. Experiments on twin-roll casting of clad strips of pure aluminum and an austenitic stainless steel of 2.5?mm total thickness with the inline abrasive cleaning of a steel substrate’s surface performed. The corresponding device for the inline surface preparation is designed. The influence of surface roughness of the substrate’s surface on the bonding strength between strip layers is analyzed. The mechanism of intermetallic bonding on the roughened surfaces is discussed. It is shown that surface roughness of steel substrate up to 4.2?µm provides bonding strength above 100?MPa.     

Laser Refining of a Surface Layer with Silicon Carbide

The article discusses the effect of adding silicon carbide by laser remelting of low-carbon steel. Tests in laser remelting were carried out with energy inputs ranging between 10 and 80 J/mm² with the most favorable degree, i.e., 30%, of overlapping of individual trace. Sufficient energy input was necessary to dissolve silicon-carbide with iron. A microchemical analysis of the remelted layer confirmed the dissolution of silicon carbide and formation of a smaller portion of martensite (10-20%) and of suesite Fe₃Si (65-80%). It was found that the test-specimen deformation was smallest with the laser-beam in the zig-zag motion. The surface was also assessed visually. The choice of adequate remelting conditions reduced, i.e., prevented, the occurrence of cracks and other defects. The influence of energy input and the mode of laser-beam travel on the efficiency of remelting, i.e., refining, was described by a ratio of the width of the remelted surface layer to its depth, which should amount to around 5:1.     

Nucleation of supercooled water on solid surfaces

Heterogeneous nucleation of water was investigated using molecular dynamics simulation. Solid with fcc (111) surface was placed at the bottom of a cell consisting of 864 water molecules. ST2 model with NPT ensemble was used. The pressure and temperature were set to be 0.1 MPa and 275 K, respectively. The interaction between water and the solid was based on the equations proposed by Spohr. Exception was made on the lattice constant which was slightly modified to fit with that for ice structure. The shape of the solid surface was considered. It was found that the only one layer of water molecules was adsorbed in a case of a flat surface, whereas ice nucleation occurred by removing some of the atoms from the surface. Spohr's interaction was also modified so that the dipole moment of water became anti-ferroelectric. It was found that the modification increased the ice growth, further. The effect of lattice constant of solid on nucleation was also investigated. It was found that the variation on lattice constant with a few percent from that of ice was acceptable for nucleation, especially on shrinking side. On expanding side, however, it gave some gaps for water molecules to fit in other than that for ice structure, and it prevented the growth of ice. Hence, a guideline for the selection of ice nucleus material was obtained.     

Microstructure and electrical conductivity of Al-SiCp composites produced by spray forming process

Al- SiC_p composites have been synthesized by spray forming process with variation in particle flow rate, size of reinforcement particles and their volume fraction. The microstructure of composites and their electrical conductivity have been investigated. The results showed a uniform dispersion of large size particulate phase in the matrix of the primary α- phase with its equiaxed grain morphology. However, clustering of small size particles was observed at the grain boundary and grain junctions. The grain size of the composite materials was observed to be lower than that of the base Al- alloy. The composite materials invariably indicated their lower electrical conductivity compared to that of the monolithic Al- alloy. The electrical conductivity of composites decreased with increase in the volume fraction and decrease in size of the reinforcement particles. A high flow rate of particles during spray deposition resulted in a decrease in its conductivity. These results are explained in the light of thermal mismatch between the matrix and the reinforcement phases resulting in generation of high dislocation density. The droplet- particle interaction and resulting microstructure evolution during the spray deposition of the composites are discussed.     

Energy and exergy analysis of single effect and series flow double effect water–lithium bromide absorption refrigeration systems

In this paper, the energy and exergy analysis of single effect and series flow double effect water–lithium bromide absorption systems is presented. A computational model has been developed for the parametric investigation of these systems. Newly developed computationally efficient property equations of water–lithium bromide solution have been used in the computer code. The analysis involves the determination of effects of generator, absorber and evaporator temperatures on the energetic and exergetic performance of these systems. The effects of pressure drop between evaporator and absorber, and effectiveness of heat exchangers are also investigated. The performance parameters computed are coefficient of performance, exergy destruction, efficiency defects and exergetic efficiency. The results indicate that coefficient of performance of the single effect system lies in range of 0.6–0.75 and the corresponding value of coefficient of performance for the series flow double effect system lies in the range of 1–1.28. The effect of parameters such as temperature difference between heat source and generator and evaporator and cold room have also been investigated. Irreversibility is highest in the absorber in both systems when compared to other system components.     

Thermal conductivity of composites

A general expression for the effective thermal conductivity of inhomogeneous media in terms of the Fourier components of the spatial variation of the conductivity is applied to composites consisting of inclusions in a continuous matrix. It is reformulated in terms of the mean square fluctuations of the conductivity. Specific cases treated are spherical inclusions and long cylinders, both random and with preferred directions. The results hold provided the difference in thermal conductivities is small or provided the concentration of inclusions is not too large. The theory fails if the thermal conductivity of the matrix is much smaller than that of the inclusions. The same considerations also apply to electrical conductivity.     

Einfluss der Werkstoffzähigkeit auf das Festigkeitsverhalten unter mehrachsiger Beanspruchung am Beispiel von Schweißverbindungen aus Stahl und Aluminium

Influence of Ductility on the Multiaxial Fatigue Behaviour by the Example of Welded Joints of Steel and Aluminium The multiaxial fatigue behaviour of materials with different ductility under constant and changing principal stress directions is also applicable to welded joints of different materials. For this, welded flange tube connections of the fine grained steel StE 460 and the artificially aged aluminium alloy AlSi1MgMn T6 were investigated under constant amplitude combined bending and torsion. Out‐of‐phase loading, i. e. changing principal stress directions, of the steel joints led to a decrease of fatigue life, which is observed at ductile material states. However, for the aluminium joints out‐of‐phase loading resulted same behaviour as in‐phase loading, which indicates a semi‐ductile material behaviour. The results for the welded steel joints were evaluated on basis of local stresses by the integral hypothesis of the Effective Equivalent Stress EES (WVS). This hypothesis for ductile material states takes into account the life decreasing influence of out‐of‐phase loading by considering the interaction of the shear stresses on different planes. The fatigue behaviour of the aluminium welds is described by the critical plane based combination of shear and normal stresses (KoNoS), which is valid for semi‐ductile material states.