近年来俄罗斯无缝钢管工业的结构调整

综述了近年来俄罗斯无缝钢管工业的结构调整情况；分析研究了近年来俄罗斯无缝钢管工业的整体发展情况和所取得的技术进步，以及无缝钢管产品的进出口量变化和钢管产品结构调整情况；介绍了俄罗斯两大无缝钢管生产集团近年来的生产经营和核心竞争力增强的情况。     

28000kN水压试验机主液压缸的有限元分析

水压试验机的组成及主液压缸的有限元分析。     

CAESARⅡ软件在水煤气变换管道设计中的应用

介绍了管道应力分析的必要性。用CAESARⅡ软件对水煤气变换过程中从变换塔到换热器的管道进行应力分析计算与优化,并总结了使用CAESARⅡ软件进行管道应力分析的注意点。     

Grasses for biofuels: A low water-use alternative for cold desert agriculture?

In arid regions, reductions in the amount of available agricultural water are fueling interest in alternative, low water-use crops. Perennial grasses have potential as low water-use biofuel crops. However, little is known about which perennial grasses can produce high quantity, high quality yields with low irrigation on formerly high-input agricultural fields in arid regions. We monitored biomass production, weed resistance, rooting depth, and root architecture of nine perennial grasses under multiple irrigation treatments in western Nevada. Under a low irrigation treatment (71 ± 9 cm irrigation water annually), cool-season grasses produced more biomass and were more weed-resistant than warm-season grasses. With additional irrigation (120 ± 12 cm water annually), warm- and cool-season grasses had similar biomass production, but cool-season species remained more weed-resistant. Among species within each grass type, we observed high variability in performance. Two cool-season species (Elytrigia elongata and Leymus cinereus) and one warm-season species (Bothriochloa ischaemum) performed better than the other tested species. Root depth was not correlated with biomass production, but species with deeper roots had fewer weeds. Abundance of fine roots (but not large roots) was correlated with increased biomass and fewer weeds. Both L. cinereus and E. elongata had deep root systems dominated by fine roots, while B. ischaemum had many fine roots in shallow soil but few roots in deeper soil. Cool-season grasses (particularly E. elongata, L. cinereus, and other species with abundant fine roots) may be worthy of further attention as potential biofuel crops for cold desert agriculture.     

对沧州市压力管道元件制造业的思考及建议

介绍了沧州市压力管道元件制造业的规模、水平及在全国的地位,阐述了"无证"和"持证"企业的生产经营情况,指出了当前存在的问题并提出了有关解决办法的建议。     

Analysis of multi-layered filament-wound composite pipes under combined internal pressure and thermomechanical loading with thermal variations

The composite pipes manufactured by filament winding technology have anisotropic behavior owing to different reinforced ply angles. Composite pipes can be exposed to the thermomechanical loading due to hot fluid that flows into them. In this paper, based on the three-dimensional anisotropic elasticity, an exact elastic solution for thermal stresses and deformations of the pipes under internal pressure and a temperature gradient has been studied. Giving heat convection conditions the variation of temperature field within the pipe is obtained by solving the conduction equation at the wall. The influence of temperature field in the governing equations of thermoelasticity has been considered via a constitutive law. The shear extension coupling is also considered because of lay-up angles. Stress, strain and deformation distributions for different angle-ply pipe designs are investigated using the present theory.     

不锈钢焊管外径尺寸精度影响因素分析

从焊管定径机机座刚度、定径设备制造精度，以及定径量、定径道次等因素人手，通过理论分析与仿真计算，得到定径设备与工艺等因素对不锈钢焊管外径尺寸精度影响的结果。分析认为，提高设备制造精度是提高不锈钢焊管外径尺寸精度的关键因素：增加定径量及定径道次是其必要手段。     

Irrigation Development and Rural Poverty in Gujarat,India: A Disaggregated Analysis

Abstract

There has been renewed interest during recent times in the impact of irrigation development on rural poverty. For long, researchers asked whether irrigation development reduces the poverty of irrigators. However, the question being asked now is: does investing in irrigation—rather than in other public works—help reduce rural poverty in a region? Using Government of Gujarat's 1997 census of Below Poverty Line (BPL) households as well as the Village Amenity Survey of the same year, this paper explores the interplay between irrigation development and rural poverty in 177 predominantly rural talukas, which is an administrative unit with a population of around 100,000-150,000 people, of Gujarat state in western India. Our analysis shows that for the design of poverty-targeting programs, two variables have the highest appeal: primary education infrastructure and improved land productivity through irrigation. It also suggests that, over the long run, irrigation benefits far transcend the command areas of irrigation systems. As a result, irrigation impact studies focused at farm or command area level seriously underestimate overall livelihood impacts of irrigation development. This is because intensively irrigated areas act as magnets that attract rural poverty from their surround, especially from other dry areas. Population pressure on farm lands thus tends to get redistributed according to the carrying capacity of farm lands. Across 177 predominantly rural talukas of Gujarat, we find: a) an inverse relationship between land use intensity and land-man ratio; and b) as land productivity (output/hectare of net sown area) declines, output per rural person declines too, but far more slowly than would have been the case without the “magnet effect.”     

耐热聚乙烯管材专用树脂的结构与性能

研究了3种耐热聚乙烯管材专用树脂的结构与性能。它们的共同特征为熔体流动速率低于0.7 g/10 min,密度为0.930~0.944 g/cm3,相对分子质量为(1.5~2.5)×105,可以为窄相对分子质量分布,也可以为中等相对分子质量分布。1-己烯共聚产品与1-辛烯共聚产品性质较为接近,都是窄相对分子质量分布,而1-丁烯共聚产品具有相对分子质量高(2.0×105以上),相对分子质量分布中等(10左右),熔体流动速率低(低于0.3 g/10min)、密度高(大于0.940 g/cm3)、拉伸屈服强度高、弯曲模量高、熔融峰温高、结晶峰温高的特点。相同条件下,1-丁烯共聚产品具有较高的黏度和模量。     

作用面积形状与布管方式对自喷系统能耗影响

自动喷水灭火系统设计时为满足规范的要求,往往存在设计压力、流量过剩的情况,造成了能量的极大浪费.对此,本文通过自动喷水灭火系统设计中最不利点处作用面积不同形状与管道布置方式对自动喷水灭火系统流量和压力的影响进行计算,可以从中得出最为节能的最不利点处作用面积形状与管道布置方式,这样可降低系统的设计压力、流量,达到降低喷淋系统能耗的目的,也验证了“喷规”第9.1.2条的合理性.