Influence of residual moisture on deep dewatered sludge pyrolysis

Wet sewage sludge pyrolysis is an attractive method for producing H₂-rich fuel gas. To reduce energy consumption for excess moisture evaporation, deep dewatered sludge was used instead of traditional high-moisture sludge in this study. The emphasis was placed on elucidating the effects of residual moisture on tar, char, and on syngas generation, and clarifying the mechanisms involved. Results show that residual bound water exerted a stronger influence on products yields and distributions than free water, since the former could work inside sludge particles while the later only acted as steam outside. At low temperature (873 K), sludge moisture increased the relative ratio of cyclic, unsaturated, and hydroxyl, aldehyde or carboxyl-containing compounds in tar, in whose generation process H₂ and carbonaceous gas were produced. When the temperature rose, water in sludge increased the surface area of the char. The breaking of C–C bonds caused by residual moisture would promote the macromolecular organic matters conversion to smaller ones, which were easy to undergo steam gasification, thus giving rise to the transformation of char–C to gas–C and enhancing H₂ yield. Therefore, the production of syngas, containing large amounts of H₂ and CO, was improved efficiently.     

Photo-hydrogen production rate of a PVA-boric acid gel granule containing immobilized photosynthetic bacteria cells

The polyvinyl alcohol (PVA)-boric acid gel granule facilitates the light penetration and mass transport as it has the features of the transparency and adequate porous structure. In this work, a hydrogen production bioreactor with the indigenous photosynthetic bacteria (PSB) Rhodopseudomonas palustris CQK 01 immobilized in a PVA-boric acid gel granule is developed to enhance the rate of photo-hydrogen production. Particular attention is paid to exploring the effects of illumination wavelength and intensity, as well as the effects of concentration, flow rate, pH, and temperature of influent substrate solution on the hydrogen production rate. The immobilized PSB gel granule exhibited the maximum hydrogen production rate of 3.6 mmol/g cell dry weight/h in all tests. The experimental results show that the hydrogen production rate of an immobilized PSB granule illuminated at 590 nm is distinctly higher than that at 470 and 630 nm. Photo-inhibition of the gel granule occurs as the long-wavelength illumination intensity exceeds 7000 lux. In addition, there exists an optimal pH of 7.0 and temperature of 30 °C for PSB immobilized in the granule to produce hydrogen. More importantly, the feasibility of PSB immobilized in the PVA-boric acid gel granule for the enhancement of the photo-hydrogen production is demonstrated.     

Preparation of porous Fe2O3/SiO2 nanocomposite abrasives and their chemical mechanical polishing behaviors on hard disk substrates

Abrasives play an important role in chemical mechanical polishing (CMP) processes. Compact solid silica particles, which have been widely used as abrasive in CMP slurries, may cause surface defects because of their high hardness. Porous silica abrasive exhibits better surface planarization and fewer scratches than traditional solid silica abrasive during the polishing of hard disk substrates. However, the improvement in material removal rate (MRR) was not significant. Therefore, porous Fe₂O₃/SiO₂ nanocomposite abrasives were prepared and their CMP performances on hard disk substrates were investigated. Experiment results indicate that the MRR of slurry containing porous Fe₂O₃/SiO₂ nanocomposite abrasives is obviously higher than that of slurry containing pure porous silica abrasive under the same testing conditions. MRR increases with the increase of the molar content of iron in porous Fe₂O₃/SiO₂ nanocomposite abrasives. Moreover, surfaces polished by slurries containing the porous Fe₂O₃/SiO₂ nanocomposite abrasives exhibit lower surface roughness, fewer scratches as well as lower topographical variations than that by pure porous silica abrasive.     

Quality and Testing Standards on Rice Production in China and Development Strategies

China is the biggest country of rice production and consumption in the world; more than 50% of the population feeds chiefly on rice. The quality of rice and its role as a staple food carry much weight. The rice qualities are those aspects concerning processing,appearance, cooking, nutrition and safety of the product.The study, formulation and implementation of standards on rice qualities and testing bear heavily on the improving of rice qualities, human health, substitution of rice varieties, promoting quality rice production and regulating rice market.     

计算机存储技术在GIS数据管理中的应用研究

介绍了计算机存储的关键技术,并结合企业级GIS数据的特点,全面阐述了如何运用这些技术,来解决GIS数据管理中遇到的问题。最后给出了建立GIS存储备份系统的技术路线。     

Insulating properties of rapid thermally processed Bi2Ti2O7 thin films by a chemical solution decomposition technique

Crack-free Bi₂Ti₂O₇ thin films on silicon substrates were prepared using chemical solution decomposition technique, and then treated by rapid thermal annealing. The microstructure of the films was studied by scanning electron microscopy. The effects of different fabricating procedures and various annealing temperatures and times on the leakage current density were investigated. The results show that the leakage current density decreases with increasing annealing temperature, while increases with increasing annealing time. Annealing temperature has a much stronger effect on the insulating properties of Bi₂Ti₂O₇ thin films than that of annealing time.     

Quantitative deterministic versus probability analyses based on a safety margin criterion

This paper proposes a new criterion called the ratio of safety margin(RSM)for use in the areas of the global factor of safety,reliability and limit states analyses with reference to their respective allowable criteria.An equation for calculating RSM based on the reliability index is formulated.Efforts for proving the applicability of this criterion include a theoretical demonstration in a simple one-variable case;an investigation on a test problem involving two random variables,followed by a slope stability study on a 156 m high embankment dam and an illustrative example presented in a EuroCode 7 guidebook.Calculation of the ratios of safety margin in the three areas provides a quantitative way to accommodate the analytical results within the same theoretical framework and makes the outcomes mutually comparable and supportive,which is much more enlightening than that would be the case by considering only one of them.Calculating RSMs for reliability and limit states methods has also helped solve the key issue concerning the uniqueness of the partial factors calibrated from a particular‘target case’.     

带钢胀径过程位移场的有限元分析

用有限元方法对带钢卷取过程中卷筒胀径进行了详细的数值模拟.在带钢卷取规程确定的条件下,研究了不同带卷层数胀径时带钢最内层节点沿卷筒的位移变化规律,得到了带钢能够稳定卷取的最小卷取层数,并定量地计算了带钢各层厚度的变化,研究结果对现场工作人员确定胀径时带卷的最小层数和提高带钢卷取速度有重要参考价值.     

铁磁材料磁记忆检测技术的研究现状

金属磁记忆检测技术作为无损检测领域的新兴学科，可以对铁磁材料构件的疲劳失效进行有效的早期诊断。在铁磁性装备部件的定寿、延寿工作中有着广阔的应用前景。综述了金属磁记忆检测技术的基本概念、检测原理及该技术的独特优点，并介绍了目前市场上已有的多种磁记忆检测仪器。分析了该技术机理的研究现状及应用情况，提出了目前存在的问题和未来发展。