Operational and safety analyses of a commercial PEMFC system

A commercial, transportable proton-exchange-membrane fuel-cell (PEMFC) system rated at 7 kW nominal power was the subject of an operational (reliability, availability, and maintainability) and process-safety analysis. The scope of the analysis included the system start-up to engine-run mode, the maintenance tasks, as well as the continuous power-production mode, carried out with a hazard and operability (HAZOP) study and a failure-scenarios' development. The failure and process-safety risks were categorized and the probabilities were assessed with a fault-tree analysis (FTA) using equipment-failure-rate data from the literature, if available. The results led to similar conclusions to those previously reported in similar studies, and the most important equipment/devices with respect to reliability and safety aspects were identified. While the most important uncertainty in the complete analysis comes from the generic equipment failure-rate data used, about three failures in the first year of operation are estimated together with an availability of about 98% (a point value figures, confidence interval analysis was also made). The process-safety analysis revealed four potential accident scenarios involving hydrogen releases, fires and explosions. Finally, detailed suggestions and recommendations for changes/improvements with respect to the reliability/availability, maintainability and safety aspects of the system analysed are presented.     

非织造布在手术服中的应用

手术服是医疗中不可缺少的纺织品，随着人们安全和健康意识的提高，对手术服的性能提出了更高的要求。本文介绍了非织造布手术服的性能要求、发展现状及生产工艺。     

几种增加非织造布强力的固结工艺探讨

介绍了几种非织造布固结工艺，并通过对不同固结工艺生产的非织造布产品的性能进行测试，说明了在生产时为了提高产品强力应注意的事项。     

一种单片智能开关电源的设计

用FAIRCHILD公司开发的一种SPS智能 (或灵巧 )功率开关设计的一种 38V、3A的单端反激式开关电源 ,小型、轻便、廉价、高效与高可靠     

芯盒结构对射砂过程的影响

利用实际生产中所使用的射芯机，分析了芯盒结构对射砂过程的影响，此外还研究了排气塞的数目对射砂过程的影响。结果表明，在射砂时，适当增另射砂孔数目，可以增加芯盒内的气压所能够达到的最大值，并且能够促进砂芯的紧实；而增加排气塞的数目时，芯盒内的气压所能够达到的最大值就会下降。     

Design of a Microstructured System for the Homogenization of Dairy Products at High Fat Content Part II: Influence of Process Parameters

Partial homogenization using a microstructured SHM (Simultaneous Homogenizing and Mixing) valve significantly reduces aggregation of fat globules within their homogenization by feeding the continuous phase directly into the droplet disruption zone (as discussed in part I of this work). It allows homogenization of cream containing up to at least 42 vol.‐% fat, and thus, significantly reduces processing costs without loss in product quality, i.e., overall process intensification. The present article details current results on the influence of material parameters, i.e., emulsifier system and fat content, and process parameters, i.e., homogenizing pressure and the temperature of both streams, on the fat globule size distribution. In contrast to conventional technology, SHM valve technology generates decreasing droplet sizes with increasing pressure or with increasing temperature of the homogenizing stream. This novel technique breaks new ground in dairy product design.     

Process and Laboratory Scale UV Inactivation of Viruses and Bacteria Using an Innovative Coiled Tube Reactor

Avoidance and elimination of viral contamination in biotechnological and pharmaceutical processes is a crucial issue. The novel UVivatec coiled tube reactor was designed for UV irradiation of cloudy liquid media. It very effectively inactivates especially critical viruses and avoids high product losses. The method proposed is an ideal complement to existing and established processes.     

Synthesis and structural properties of lithium titanium oxide powder as-synthesized by two step calcination process

A two-step calcination synthesis, considering the potential for mass production, of lithium titanium oxide powder was carried out to fabricate a single Li₄Ti₅O₁₂ phase, which is useful for anode electrode material of Li-based rechargeable battery as well as an electrode for supercapacitor. The final composition is controlled by adding more TiO₂ powder into powder gained at one calcination process during the two calcination process. We investigated the influence of excess TiO₂ on the structural characteristics of lithium titanium oxide synthesized by the two-step calcination method. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) measurements showed that the as-synthesized powder had a spinel crystal structure as well as A composition of 4: 5: 12. In addition, a high resolution transmission electron microscopy (HRTEM) analysis revealed that the fabricated powder exhibited a single crystalline phase formation. These results indicated that the powder synthesized in the one-step calcination process showed coexistence crystalline phases, which are the Li₄Ti₅O₁₂ and Li_2.39Ti_3.4O₈ phase. However, in the two-step calcination process, the powder synthesized showed the single crystalline Li₄Ti₅O₁₂ phase. A very uniform grain size of the as-synthesized powder was shown in a field emission scanning electron microscopy (FESEM). These results suggested that the two-step calcination process can be used for synthesis of single crystalline Li₄Ti₅O₁₂ powder with uniform grain shape and provide motivation to pursue mass production of lithium titanium based oxide powder for bulk type batteries.     

强化生产过程控制提高精铸件质量

分析了国内不锈钢精铸企业与国外的差距,总结了强化生产过程控制,提高精铸件质量的经验.为提高铸件尺寸精度,须从加强批量生产前的试制和批量生产中的过程控制两个方面着手,强化产品工艺设计、严格模具、蜡件、铸件的尺寸检测,在生产过程中严格控制蜡料质量以及射蜡温度、储存蜡件空间的温度、湿度等.为避免铸件表面缺陷,除控制涂料浆的粘度、SiO2含量、pH值外,还应控制型壳面层干燥的湿度并保持温度均匀,碳钢炉料和回炉料须100%抛丸清理.