Study on operating characteristics of fuel cell powered electric vehicle with different air feeding systems

In this paper the modeling of a fuel cell powered electric vehicle is presented. The fuel cell system consisting of a proton exchange membrane (PEM) fuel cell stack and balance of plant (BOP) was co-simulated with a commercial vehicle simulation program. The simulation program calculates the load of the fuel cell depending on the driving mode of the vehicle and also calculates the overall efficiency and each parasitic loss by applying the load in the fuel cell model that is used to estimate the performance of the entire vehicle system by calculating the acceleration performances and fuel economy of the vehicle. Two types of air feeding systems (blower type and compressor type) were modeled by using MATLAB/Simulink environment and the effect of fuel cell stack size (number of cells, cell area) on the fuel economy and performance of the fuel cell powered vehicle was investigated. Using a driving cycle of FTP-75, the required power, BOP component power loss, and system efficiency for two types of fuel cell systems were analyzed. Through this study, we could get a basic insight into the fuel cell powered electric vehicle and its characteristics.     

碳酸镉转化制备氢氧化镉及产物光催化降解性

用碳酸钠溶液直接混合硫酸镉溶液制备了沉淀碳酸镉,再以沉淀碳酸镉为基体,氢氧化钠溶液为转化剂,通过阴离子交换制备出氢氧化镉纳米材料。采用X射线衍射仪（XRD）和场发射扫描电子显微镜（FESEM）对沉淀碳酸镉和转化产物的结构和形貌进行了表征。结果表明,沉淀碳酸镉的结构遭到破坏,转化完全所得到的氢氧化镉的形貌完全不同于沉淀碳酸镉,为片状组装的不规则球体。紫外光照射下光催化降解罗丹明B染料测试表明,转化产物比沉淀碳酸镉具有更好的光催化降解性能,转化时间不同的产物表现出不同的降解效率。当20 mg的转化产物分散到50 mL 8 mg/L的罗丹明B染料中,在黑暗环境中磁力搅拌吸附120 min达吸附平衡,开启300 W紫外汞灯后,效率最高的转化产物可在180 min内将染料完全降解。     

全硫化超细粉末橡胶对PVC-U力学性能及形态的影响

研究了未增塑聚氯乙烯／粉末橡胶共混物的力学性能和形态特征。研究发现，随粉末橡胶用量增大，共混物的冲击强度先有所降低然后逐渐上升。实验结果和电镜图像表明：粉末橡胶基本粒子均匀分散的效果是影响共混物冲击韧性高低的重要因素；环氧化天然橡胶有促进粉末橡胶分散、改进增韧效果的作用。基本断裂功方法的研究结果表明，共混物的比基本断裂功随粉末橡胶用量增多而降低，比非基本断裂功则随之而升高，且断裂功的变化主要表现在材料屈服之前。     

Regulation of Amylose Content by Single Mutations at an Active Site in the Wx-B1 Gene in a Tetraploid Wheat Mutant

The granule-bound starch synthase I (GBSSI) encoded by the waxy gene is responsible for amylose synthesis in the endosperm of wheat grains. In the present study, a novel Wx-B1 null mutant line, M3-415, was identified from an ethyl methanesulfonate-mutagenized population of Chinese tetraploid wheat landrace Jianyangailanmai (LM47). The gene sequence indicated that the mutated Wx-B1 encoded a complete protein; this protein was incompatible with the protein profile obtained using sodium dodecyl sulfate–polyacrylamide gel electrophoresis, which showed the lack of Wx-B1 protein in the mutant line. The prediction of the protein structure showed an amino acid substitution (G470D) at the edge of the ADPG binding pocket, which might affect the binding of Wx-B1 to starch granules. Site-directed mutagenesis was further performed to artificially change the amino acid at the sequence position 469 from alanine (A) to threonine (T) (A469T) downstream of the mutated site in M3-415. Our results indicated that a single amino acid mutation in Wx-B1 reduces its activity by impairing its starch-binding capacity. The present study is the first to report the novel mechanism underlying Wx-1 deletion in wheat; moreover, it provided new insights into the inactivation of the waxy gene and revealed that fine regulation of wheat amylose content is possible by modifying the GBSSI activity.     

Morphologies and dynamic mechanical properties of core‐shell emulsifier‐free latexes and their copolymers for P(BA/MMA)/P(MMA/BA) and P(BA/MMA)/PSt systems in the presence of AHPS

Different poly(methyl methacrylate/n‐butyl acrylate)/poly(n‐butyl acrylate/methyl methacrylate) [P(BA/MMA)/P(MMA/BA)] and poly(n‐butyl acrylate/methyl methacrylate)/polystyrene [P(BA/MMA)/PSt] core‐shell structured latexes were prepared by emulsifier‐free emulsion polymerization in the presence of hydrophilic monomer 3‐allyloxy‐2‐hydroxyl‐propanesulfonic salt (AHPS). The particle morphologies of the final latexes and dynamic mechanical properties of the copolymers from final latexes were investigated in detail. With the addition of AHPS, a latex of stable and high‐solid content (60 wt %) was prepared. The diameters of the latex particles are ～0.26 μm for the P(BA/MMA)/P(MMA/BA) system and 0.22–0.24 μm for the P(BA/MMA)/PSt system. All copolymers from the final latexes are two‐phase structure polymers, shown as two glass transition temperatures (T_gs) on dynamic mechanical analysis spectra. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3078–3084, 2002     

分离有机/有机混合物的PVA、CA系列膜及其渗透汽化性能研究(Ⅰ)膜材料与成膜工艺

依据溶度参数原则和分离甲基叔丁基醚(MTBE)/甲醇(MeOH)混合物的选择渗透性,选择了聚乙烯醇(PVA)为复合膜的分离层材料,聚丙烯腈(PAN)、醋酸纤维素(CA)系列为支撑层的膜材料.初步讨论了膜材料和复合膜结构对分离性能的影响,给出了用不同成膜工艺制备的膜性能,获得了可用于有机/有机体系分离的性能优良的PVA/PAN和PVA/CA复合膜,以及CTA中空纤维渗透汽化膜.     

Modeling heat transfer in screw extrusion with special application to modular self‐wiping co‐rotating twin‐screw extrusion

This paper proposes two important models useful for describing heat transfer and temperature profiles in single and modular self‐wiping co‐rotating twin‐screw extruders. One model predicts heat transfer coefficients. Calculations of the barrel and screw heat transfer coefficients are made for various modules in different diameter extruders. We compare the values of the heat transfer coefficients from the model with those from literature. The second model predicts the axial screw temperature profile when the barrel, but not the screw, is heated, Example calculations of the cup mixing and screw temperature profiles are also made for different diameter extruders.     

金属磁记忆检测技术概况及初步应用

介绍金属磁记忆检测技术的背景、发展、现状、目的和意义，用两个应用实例初步评价了磁记忆检测技术的有效性，提出了磁记忆技术发展的近期和远期目标，展望了应用前景。     

Enhanced light emission of nano-patterned GaN via block copolymer thin films

We demonstrate that the nanoscopic block copolymer patterns on GaN can enhance light extraction efficiency of GaN-based light emitting diodes. Nanoporous patterns were fabricated on a bare GaN substrate via self-assembly of poly(styrene-b-methyl methacrylate) block copolymers from which PMMA microdomains were selectively removed later on. A bare GaN surface was treated with a photo-crosslinkable thin layer of poly(styrene-r-methyl methacrylate) random copolymers to tune the cylindrical microdomain orientations. The nanoporous block copolymer thin film was controlled to be thicker than its typical repeat period in bulk by incorporating PMMA homopolymer into block copolymer. Consequently, the light extraction efficiency in photoluminescence spectra could be tuned with the thickness of nanopatterned thin film on GaN. This paper is dedicated to Professor Chul Soo Lee on the occasion of his retirement from Korea University.