聚酯型粉末涂层附着力异常的原因分析

针对热镀锌板表面聚酯型粉末涂层附着力异常的问题,对比了涂层脱落和正常前处理的基材表面形貌、元素组成、清洁度和红外光谱,得出涂层附着力异常的原因为基材表面在喷涂前发生氧化和油污未除净,给出了相应的解决措施。     

Should I scan my face? The influence of perceived value and trust on Chinese users’ intention to use facial recognition payment

While China has seen the widespread adoption of facial recognition payment, concerns over the potential risks impede the further growth of user acceptance. Drawing on the perspectives of perceived value and trust, we developed a research model to explore how the Chinese users’ trade-off between perceived benefits (perceived convenience and perceived novelty) and perceived risks (perceived privacy risk and perceived financial risk) influences their usage intention. Based on survey data from 1,200 Chinese mobile payment users, this study uses structural equation modeling to examine the hypotheses. Our results show that perceived convenience positively influences perceived value, while privacy risk and financial risk negatively influence perceived value and trust. Although perceived novelty has no significant effect on perceived value and trust, perceived value positively influences trust, and both of them have a positive effect on the intention to use. Furthermore, our moderation analysis indicates that the influence of perceived value on the intention to use is stronger among users who consider facial information to be more sensitive. The theoretical implications for research as well as the practical implications for practitioners are also discussed.     

商用多联机室外机电机支架动力学分析及优化设计

利用有限元仿真技术对某商用多联机室外机电机支架进行动力学分析,并利用试验结果证明仿真计算结果的准确性。基于仿真计算结果对电机支架进行优化设计,有效解决电机支架的共振问题。     

Characterization and application of propylene grafted hydrogenated dicyclopentadiene hydrocarbon resin

Hydrocarbon resins, which are defined as low molecular weight, amorphous, and thermoplastic polymers, are widely used as tackifiers for various types of adhesives, as processing aids in rubber compounds, and as modifiers for paint and ink products, and for use in plastics polymers such as isotactic polypropylene. Recently, the quantities of the hydrocarbon resin׳ raw materials which are the side products from naphtha cracking process have decreased because of light-feed cracking such as gas cracking, so new raw materials for hydrocarbon resin production are essential. To be satisfied with the previously mentioned factors, the substitution of hydrocarbon resin raw materials with renewable resources is a worthy consideration. Moreover, new hydrocarbon resin having high adhesion performance, low specific gravity, and good compatibility with various polymers has been requested in various adhesives.To meet those requests, in this study, propylene instead of side product from naphtha cracking as main raw material of hydrocarbon resin were partially used. The propylene serves as a new, sustainable raw material and was successfully grafted onto dicyclopentadiene. The reaction of the propylene with dicyclopentadiene was confirmed because, according to NMR and FT-IR analyses, a pendant methyl-propylene group exists in the structure of the propylene-grafted, hydrogenated dicyclopentadiene hydrocarbon resin. To establish an optimal production condition regarding the propylene-grafted, hydrogenated dicyclopentadiene hydrocarbon resin, numerous experiments were conducted according to the mole ratio of the raw materials and the polymerization temperature. The propylene-grafted, hydrogenated dicyclopentadiene hydrocarbon resin that was manufactured according to optimal conditions results in a lower specific gravity and a high molecular weight, whereby the advantages of the adhesion properties of an SIS-based pressure-sensitive-adhesive are exploited. When the propylene-grafted, hydrogenated dicyclopentadiene hydrocarbon resin was formulated with the SIS-based pressure-sensitive-adhesive, both the heat stability and the shear-adhesion strength are sound.     

Nonlinear PI control for variable pitch wind turbine

Wind turbine uses a pitch angle controller to reduce the power captured above the rated wind speed and release the mechanical stress of the drive train. This paper investigates a nonlinear PI (N-PI) based pitch angle controller, by designing an extended-order state and perturbation observer to estimate and compensate unknown time-varying nonlinearities and disturbances. The proposed N-PI does not require the accurate model and uses only one set of PI parameters to provide a global optimal performance under wind speed changes. Simulation verification is based on a simplified two-mass wind turbine model and a detailed aero-elastic wind turbine simulator (FAST), respectively. Simulation results show that the N-PI controller can provide better dynamic performances of power regulation, load stress reduction and actuator usage, comparing with the conventional PI and gain-scheduled PI controller, and better robustness against of model uncertainties than feedback linearization control.     

Undergraduate studies in energy education – A comparative study of Greek and British courses

Undergraduate energy education in Greece is compared with relevant accredited courses of the United Kingdom, with the aim to transfer good practices applied in the latter for the development and improvement of the Greek courses. Despite the encouraging prospects for energy engineering courses, the situation in Greece seems declining, with only one course being offered in this period. The (unique) Greek course seems to share the same basis with the majority of the British accredited courses, but also a few peculiarities that could be amended for the improvement of the course.     

双螺杆制冷压缩机性能影响因素的试验研究

对双螺杆制冷压缩机的转子啮合间隙、内容积比、注油量以及吸气流速等进行试验研究,得出了性能随间隙、内容积比、注油量、流速等变化的关系。研究结果表明,在一定运行范围内,啮合间隙增加0.01~0.02mm,性能下降1.5%~3%;制冷工况下内容积比选在2.6、吸气流速在9m/s时,压缩机能够获得较好的综合性能;回油量达到吸气质量流量的3%时性能最佳。     

空调产品结构设计间隙检查系统开发

随着企业的产品日益向高档化、精致化发展,出于外观、运行平稳性、产品寿命等方面的考虑,对产品设计中的配合间隙控制提出了越来越高的要求。针对空调行业的应用,利用Pro/TOOLKIT二次开发技术,研发出一套高效的基于Pro/E平台的产品间隙控制系统,实现设计间隙检查表自动输出和更新,达到了减少设计重复工作、提高产品开发效率的目的。     

Reclaimed water distribution network design under temporal and spatial growth and demand uncertainties

A significant—but underutilized—water resource is reclaimed water, i.e., treated wastewater that is reintroduced for various purposes. Especially in water scarce regions, reclaimed water is often the only remaining source of water to meet increasing population and water demands. In this paper, we develop a new model formulation for the cost-effective branched reclaimed water network design and solve it with an exact optimization method. We consider both construction and energy costs expended over a twenty-year period. Unlike other formulations, uncertain reclaimed water demands, temporal and spatial population changes are explicitly considered in our two-staged construction and expansion model. In order for the system to meet higher demands during the peak times and to evaluate energy use, we consider two pumping conditions: one with average demands, which is used to compute the average energy consumption, and the other with peak demands, which dominates pipe size and pump station capacity selection. By introducing binary variables that indicate discrete pipe and pump sizes, we linearize the nonlinear hydraulic equations and objective function terms. We develop methods to significantly reduce the problem dimension by exploiting the problem characteristics and network structure. Our computational results indicate that these methods are very effective. Finally, we apply our model to design a reclaimed water network for a realistic municipal system under estimated demand and population scenarios, and analyze the sensitivity of the system to model parameters.     

Removal of cadmium and zinc ions from aqueous solution by living Aspergillus niger

1 Introduction Heavy metals like copper, mercury, chromium, cadmium, lead, nickel and zinc cause serious threat to environment, animals and human for their extreme toxicity[1]. Many industries including metal plating, mining, battery, pigment, dyestuff a…