基于神经网络与PID控制的微制造试验平台隔振系统的混合控制

利用神经网络与PID控制算法,提出了一种针对微制造平台振动的混合控制方法。该方法较好地实现了神经网络与PID算法的结合,弥补了微制造系统动态性能差的缺陷。仿真结果表明,该方法具有良好的减振效果。     

Al-Zn-Mg-Zr高强度铝合金超塑性的研究(Ⅰ)——制取工艺、超塑性力学特性及显微组织

已掌握试验合金超塑性板材的制取工艺,获得平均晶粒大小为7.78μm截长的细晶。该板材的超塑性力学特性系统试验表明,于550℃ε_0=(3.3～6.6)×10~(-1)分~(-1)范围拉伸变形,能获得δ=890～1050％、m≥0.4的较佳超塑性。超塑性变形后断裂试样的显微解析揭示,断裂处附近不仅晶粒粗大(>20μm)而且有密集孔洞,孔洞大小相当于一个粗大晶粒,试验合金系孔洞敏感材料。     

企业级移动互联微信信智能服务平台设计实现研究

《移动互联微信信智能服务平台》致力于为企业打造优秀的公众服务平台,提升客户消费体验与服务.通过定制微信信服务的商家或者企业,可以为客户提供有价值信息的订阅;添补微信O2O业务流程中的沟通环节的缺失;提升客户的商业咨询活跃度、促进移动消费习惯;提升客户的服务体验,拉近与客户之间的关系.本文介绍企业级移动互联微信智能服务平台设计实现模块组成.     

An effectiveness-based adaptive cache replacement policy

Belady’s optimal cache replacement policy is an algorithm to work out the theoretical minimum number of cache misses, but the rationale behind it was too simple. In this work, we revisit the essential function of caches to develop an underlying analytical model. We argue that frequency and recency are the only two affordable attributes of cache history that can be leveraged to predict a good replacement. Based on those two properties, we propose a novel replacement policy, the Effectiveness-Based Replacement policy (EBR) and a refinement, Dynamic EBR (D-EBR), which combines measures of recency and frequency to form a rank sequence inside each set and evict blocks with lowest rank. To evaluate our design, we simulated all 30 applications from SPEC CPU2006 for uni-core system and a set of combinations for 4-core systems, for different cache sizes. The results show that EBR achieves an average miss rate reduction of 12.4%. With the help of D-EBR, we can tune the weight ratio between ‘frequency’ and ‘recency’ dynamically. D-EBR can nearly double the miss reduction achieved by EBR alone. In terms of hardware overhead, EBR requires half the hardware overhead of real LRU and even compared with Pseudo LRU the overhead is modest.     

活性自由基接枝聚合反应合成氯化聚乙烯接枝聚苯乙烯的研究

用氯化聚乙烯与铜试剂二乙基二硫代氨基甲酸钠反应合成了分子链上带有多个引发基团的大分子引发剂，用此引发剂引发苯乙烯聚合得到了氯化聚乙烯接枝聚苯乙烯（ＣＰＥ－ｇ－ＰＳ）接枝共聚物。采用紫外光谱、核磁共振氢谱对大分子引发剂和接枝共聚物进行了表征。结果表明：含有二乙基二硫代氨基甲酸酯的大分子引发剂可以在简单易行的聚合条件下合成可控结构接枝共聚物，并有很高的接枝率和接枝效率     

聚合物微球提高低渗油藏渗吸效率微观实验研究

为了研究聚合物微球对低渗油藏渗吸采收率的作用效果,通过物理模拟实验和微观实验的方法分析了聚合物微球对剩余油的动用情况,研究了岩心自发渗吸的最佳效果。结果表明:带有聚合物微球的溶液与未加入聚合物微球的溶液相比对提高采收率起到了一定的作用,采收率在14%~15%,渗吸过程主要靠重力的作用凭借逆向渗吸的方式将原油置换出来。从微观实验可以看出聚合物微球对动用簇状剩余油有明显效果,对孔道进行了封堵,提高了渗吸液的波及体积,进而提高了采收率。     

Vibration assisted wire electrochemical micro machining of array micro tools

Micro structures and components are widely used in modern industries, and micro machining has therefore become a popular research topic. As micro tools are essential in micro machining, wire electrochemical micro machining is introduced in the fabrication of micro tools in this paper, and micro square column tool arrays are fabricated using wire cathodes by two steps. In order to improve the machining efficiency and quality, an electrode vibration technique is used, and the effects of bubble behaviour on slit width homogeneity and edge radius are studied through simulations of the electric field. The influences of various machining parameters such as vibration conditions, electrical properties, electrolyte concentration and feedrate on the standard deviation of the slit width and on the value of the edge radius are investigated. In addition, the micro dimple array is fabricated using electrochemical micro machining by employing the micro square column tool array as the cathode.     

Effects of machined cavity texture on ejection force in micro injection molding

The friction force developed in the demolding phase of the micro injection molding process is mainly determined by mold surface finish, which affects the tribological phenomena occurring at the polymer–tool interface. In this work, the effects on the ejection force of two cavity surfaces machined with different technologies (viz. micro milling and micro electro discharge machining), but with similar value of Ra, were investigated. The relations between different surface topography parameters and the ejection force were then analyzed, in order to identify the parameters that most appropriately describe the friction at the polymer–tool interface. The experimental results showed the strong interactions between the mold surface texture and the micro injection molding process parameters that promote the replication, such as mold temperature and holding pressure. The different machining technologies generated two mold textures that have a similar value of Ra, but their influence on friction can be properly described only using several other surface topography parameters.     

Effect of particles micro characteristics destroyed by ball milling on fly ash electrostatic separation

It is meaningful to investigate fly ash triboelectrostatic separation from a microscopic point of view. The ball milling pretreatment was proposed to improve the recycling efficiency (RC) of unburned carbon in fly ash. Particles models were established referring to the microscopic characteristics of particles obtained by scanning electron microscope (SEM). Electrostatic separation of three particles with different microscopic characteristics was analyzed by CFD-DEM coupled calculation. The comparative experiments between pretreated and untreated particles were performed. The feasibility of ball milling pretreatment was evaluated based on the loss on ignition (LOI) and productivity (PR). The results show that microscopic characteristics of particles have a serious impact on separation. Higher voltage is beneficial to the separation, but the flow velocity needs to consider the particles characteristics. It is difficult to realize high-efficiency separation by adjusting flow velocity and voltage. The ball milling treatment can destroy the complex microscopic characteristics of particles and reduce the particle size. As compared with untreated particles, the RC and PR of unburnt carbon for particles treated by ball milling can be increased by 2.19% and 32.38% respectively. The flow velocity of 10 m/s and voltage of 15 kV are suitable operating conditions.     

Grain Refinement through Shear Banding in Severely Plastic Deformed A206 Aluminum Alloy

The present work is conducted to study the microstructure and texture evolutions in an as‐cast A206 aluminum alloy after applying severe plastic deformation. Toward this end, the material is severely deformed through accumulative back extrusion (ABE) technique at 200 °C and followed by assessing the room temperature mechanical properties of the products. The macro shear‐bands formation in the highly strained regions can result in grain refinement through the geometric dynamic recrystallization mechanism. A significant refinement is also characterized within the micro shear‐bands; this is attributed to the intensified substructure development and the occurrence of continuous dynamic recrystallization. The corresponding inverse pole figure maps show similar orientation for these newly refined grains with the parent ones. A random texture is produced through sub‐grain rotation to dissimilar orientation at the intersection of micro‐bands. The assessment of mechanical properties of the processed materials reveal significant increase in both yield and ultimate tensile strength values. The hardness profiles also demonstrate a relatively homogenous microstructure after three and five ABE passes holding a mean hardness value of 183 Vickers.