独立光伏发电系统双向变换器数字控制器设计

提出一种独立光伏蓄电池,超级电容混合储能系统.与传统的独立光伏发电系统相比,新系统具有高功率密度、高能量密度、延长蓄电池的使用寿命、效率高、稳定性好等优点.双向变换器在该系统中承担双向传送能量的任务,对其数字控制系统进行了设计,并采用抗积分饱和控制算法的PID调节器.由于DSP硬件没有移相控制器,提出一种基于移相调节控制的软件方案来实施移相控制.最后通过仿真和实验结果验证了该方案的有效性.     

基于TL494的H桥直流电机控制系统

介绍了以TL494为核心,采用PWM技术的直流电机控制系统。基于TL494的H桥直流电机控制系统可简化电路结构、驱动能力强、功耗低并且控制方便,性能稳定。     

Unintentionally produced dioxin-like polychlorinated biphenyls during cooking

The formation and distribution of dioxin-like polychlorinated biphenyls (dl-PCBs) during cooking was investigated. Concentrations of dl-PCBs in liquid residues, cooked beef, and oil fumes generated during heating were determined by isotope dilution HRGC/HRMS. Although the levels of dl-PCBs in well-done beef were lower compared with those of raw beef, relatively high concentrations of dl-PCBs were detected in the oil fumes produced during heating. This suggests that dl-PCBs in raw beef may have volatilized into the oil fumes during the cooking process. Sucralose and chloropropanols contained in raw materials may have resulted in increased dl-PCB concentrations and the level of toxic equivalents (TEQ) in the oil fumes produced under high temperature during cooking. Concentrations of dl-PCBs did not vary greatly in cooked beef, except when higher levels of chloropropanols were presented in the uncooked raw materials. Results indicate that sucralose and chloropropanols may promote the formation of dl-PCBs during the cooking process. The newly produced dl-PCBs from raw beef cooking were mainly present in oil fumes, which gave rise to high levels of TEQ in oil fumes.     

印刷专业教师研讨会在河内举行

德国印刷促进会在国外为专业教师举办的第二次研讨会,于3月23日至25日在越南河内印刷工业学院(Hanoi college of printing industry)成功举办。出席研讨会的约50名专业教师,来自印尼和越南的10所不同的大学和培训中心。     

超级高达改

我这次制作的模型是RX-178+FXA-05D SUPER GUNDAM俗称超级高达。套件使用的是万代MG2.0奥干配色的Mk-II高达和MG1.0的G防卫者。套件制作时主要     

硅藻土涂料在热模法离心铸造球铁管中的应用

采用硅藻土为骨料配制的悬浊液作为涂料涂覆于管模内壁生产球铁管,论述了涂料原材料选择、涂料配制、性能及合适的施涂方式。试验表明,膨润土浆持续搅拌2h,再静止10h后配制涂料;硅藻土是涂料热模法中最合适的骨料;对于小管径的管模涂料,膨润土含量高一些,硅藻土与膨润土的质量比为(8～15):1;对于大口径管模涂料,膨润土含量稍低,硅藻土与膨润土质量比为(12～20):1,另外,有气喷涂是最佳的喷涂方式。     

Study on Microstructure and Mechanical Properties of Hot Rolled Low Silicon Containing Phosphorus TRIP Steel

The effects of final air cooling temperature on the microstructure and mechanical properties of hot rolled 0.2C-1.9Mn-0.5Si-0.08P TRIP steel were studied by utilizing OM, SEM, TEM and tensile tests. Experimental results showed that in the multiphase microstructure of the investigated steel when the finish rolling temperature was about 820 ℃ and the final air cooling temperature was in the range of 630-700 ℃, the grain size of most of ferrite was finer (about 4 μm) and which had higher dislocation density, t...     

Strategic justification of advanced manufacturing technology using an extended AHP model

Layered manufacturing has emerged as a highly versatile process to produce complex parts compared with conventional manufacturing processes, which are either too costly to implement or just downright not possible. However, this relatively new manufacturing process is characterized by a few outstanding issues that have kept the process from being widely applied. One such issue is the reduced part accuracy caused by the primitive method of generating the layer contours. Current practice generates the layer contours by simply intersecting a set of parallel planes through the computer model of the design part. The volumetric geometry of each layer is then constructed by extruding the layer contour by the layer thickness in the part building direction. This practice often leads to distorted part geometry due to the unidirectional bias of the extruded layers. This paper proposes a novel scheme to correct the systematic part distortion of layered manufactured parts resulting from the improperly generated layer contours. A new layer contour generation method utilizing the sectional projected data of a point cloud representation of the part surface is introduced. The systematic part distortion is reduced by extruding the outer boundary of the projected point data into the layer volumetric geometry. The boundary contour construction algorithm is able to adapt to changing density of the point set in order to keep the captured level of detail consistent. Specifically devised case studies were carried out to validate the proposed method.