缠绕式垫片分级设计制造理论和技术

通过不同材料、不同结构的组合以及制造工艺参数的合理选择,可制成不同性能的缠绕式垫片以适应不同介质、不同工况的使用要求。提出了缠绕式垫片分级设计与制造的概念,建立了基于垫片结构参数和生产工艺参数优化以及螺柱凸缘联接紧密性分析方法的分级设计制造理论,探讨了相关技术。实践表明,该技术的推广应用可有效提高缠绕式垫片的设计、制造和使用水平。     

在埋弧焊管生产线上定量给料装置的改进

分析了原有定量给料装置存在的４方面的问题，通过研究，对定量给料装置进行了改进，改进后的给料装置运行状况良好。     

八字形螺旋槽端面密封及其系统在2MCL—457离心压缩机上的试应用

介绍了八字形螺旋槽端面密封及其系统在２ＭＣＬ－４５７型离心式富气压缩机上的应用情况该密封及其系统具有较大的推广价值。     

Consumer‐diet discrimination of δ13C and δ15N: Source‐ and feeding‐oriented patterns based on gut content analysis in a large subtropical river of China

Understanding the trophic discrimination (?¹³C and ?¹⁵N) between consumers and diets in fluvial systems remains difficult because of the variable food sources and complex predator–prey interactions from headwaters to the estuaries. Here, stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes in fish and invertebrates from a large subtropical river in southern China were determined to explore trophic discrimination in conjunction with a gut content analysis. The ?¹³C values showed significant differences (p < .05) among functional feeding groups, with fish, shrimp, and insect scrapers presenting higher ?¹³C values (1.20 ± 0.23‰ to 1.51 ± 0.31‰) than other groups. The ?¹⁵N values varied significantly between invertebrates (0.64 ± 0.17‰ of insect collector‐gatherers to 1.63 ± 0.36‰ of shrimp predators) and fish (1.98 ± 0.19‰ of detritivores to 2.71 ± 0.43‰ of crustaceavores) and exhibited an increasing tendency from primary to secondary consumers. A linear regression analysis revealed that the longitudinal changes in ?¹³C and ?¹⁵N were closely associated with the δ¹³C of periphyton, the δ¹⁵N of particulate organic matter (POM) in water, and the relative contribution (%) of periphyton and organic detritus to the diet composition of consumers. These results indicated that discrimination factors might not only be influenced by the isotope signatures of basal food sources but also downstream shifts in dominant food items utilized by consumers. In particular, trophic discrimination between periphyton– and detritus–based food chains, such as “epilithic diatoms–shrimp scrapers–crustaceavorous fish” and “POM–bivalves–molluscivorous fish,” displayed regionally specific patterns. When back‐calculating to the diet assimilation and trophic position in subtropical streams and rivers, we suggest using the basin‐scale ?¹³C value of 0.96 ± 0.26‰ for all consumers and ?¹⁵N values of 1.07 ± 0.32‰ for invertebrates and 2.38 ± 0.37‰ for fish.     

关键链汇入缓冲区的设置方法

在介绍现有关键链(Critical chain scheduling,CCS)汇入缓冲区(Feeding buffer)设置方法及其优缺点的基础上,提出一种改进的汇入缓冲区设置方法.将汇入缓冲区的设置划分为汇入位置和汇入缓冲区大小的确定,并分析了缓冲区设置过程中的资源冲突问题.     

湖南省科技馆方案设计

文章介绍了湖南省科技馆方案设计的创作理念、基本功能布局设计、重点部位与细节处理,以及生态设计的一些尝试性的构思,并提出当今时代的经济技术条件为建筑师提供了更为广阔的创作空间,建筑师应当充分激活创作思维,掌握先进的设计技术,深入发掘民族的、地域的文化内涵,创作出有新意,有个性的建筑作品来。     

300MW机组锅炉启动上水加热过程探讨

介绍了靖远第二发电有限公司300 MW机组简况,锅炉启动点火前的3种上水方式及相关操作。分析了启动过程中存在的一些问题,并提出了系统改造的一些建议和操作中的注意事项。     

超声辐照合成超细NiO的研究

以氯化镍为镍源,碳酸氢铵为沉淀剂,采用液相沉淀–热分解法制备NiO。合成过程中引入超声场,并考察了不同加料方式对产物粒度和纯度的影响。采用SEM,XRD,激光粒度分布测定技术和离子色谱技术分别对产物进行表征。结果表明,在前驱体制备过程中引入功率超声可以减小产物NiO的粒径,且使形状更加规整;在有超声作用下采用并加加料方式制得了晶粒度为5~10nm,平均粒径为1.10μm,w(Cl–)为0.056%的立方晶系的NiO。     

钢管挡拨料机的类型及应用

介绍了近几年钢管生产线上几种技术比较先进的挡拨料机类型,如星轮拨料机、翻料钩、翻板装置、挡翻料机、挡料给料机等,以及这些设备的组成和特点;分析了挡拨料机在不同的场合下发挥的作用。在生产实践中,结合用户不同的需要、不同的生产节奏,合理选用挡拨料机,将有利于优化工艺生产线,提高钢管的质量和产量。     

On the feasibility of on-farm biogas-to-electricity conversion: To what extent is solid oxide fuel cells durability a threat to break even the initial investment?

Despite their promising features, adverse economic feasibility still hamper SOFCs wide implementation and this effect is emphasized as long as the system size is reduced. According to previous investigations, the biogas pre-treatment section represents a burden for the economic viability. Aiming at reducing the extent of installation costs in SOFC-based configurations, biogas partial upgrading through CO₂ gas-separation membranes is put forth as innovative solution against reforming. This innovative system concept is expected to make SOFCs more cost-effective, yet resulting feeding gas might cause a quicker SOFC performance decay. Besides solving this trade-off, the economic viability results strongly sensitive to subsidiary electricity prices in force according to the regulatory framework.This paper presents a comparative economic assessment regarding biogas-to-electricity conversion via Solid Oxide fuel cells (SOFCs) and mature technologies as internal combustion engines (ICEs). Results highlighted that, the innovative SOFC system is far more viable than reforming-based one, exhibiting a reasonable payback time, with an adequate subsidized electricity sale price (4 and 5 years for small/medium and large-size plants respectively when subsidy is 0.28 €/kWh), up to 1%_1000h degradation rate. On the other hand, whilst considering a SOFC degradation rate of 0.03%_1000h, the reforming-based system appears feasible only on large-size plants, yet recovering the initial capital expenditure in 9 years. Moreover, once the break-even point is reached, the gain in the net revenue produced by the innovative system is amplified in the event of small-size installation. This allows the possibility to undertake the risk of higher degradation rates (up to 2%_1000h) without jeopardizing the economic profitability. Therefore, in the present regulatory framework and under current capital costs projections, the innovative SOFC system appears as much profitable as ICE mature technology. Such effort in the design of the fuel pre-treatment unit can lever SOFC broad spreading into the market of small biogas producers.