Experimental study of wear interaction between piston ring and piston groove in a radial piston hydraulic motor

The wear interaction between piston ring and piston groove in a radial piston hydraulic motor was studied in regard to mass loss and changes in form and surface roughness. A specially developed test rig that simulates the tilting movements of pistons at the end of strokes was used in the test. The results show that wear on the piston ring groove can be up to 10 times greater than the wear on the piston ring. For both interacting surfaces, the dominant wear mechanism was mild wear. The results from a factorial design show that the form of the piston groove significantly influences the amount of wear.     

Elastic–plastic solid disk with nonuniform heat source subjected to external pressure

The elastic–plastic stress distribution of a solid disk due to nonuniform heat source under external pressure is investigated in this work. The nonuniform heat generation rate is taken to be a function of the radial position in the form , where a denotes radius of the solid disk; q₀, n and s are constants. The exact solution presented is based on the usual assumptions of plane stress, Tresca's yield condition, its associated flow rule and linear strain hardening material behaviour. According to this analysis, the plastic core in the general case consists of three parts with different forms of the yield condition. The present solution is illustrated by numerical results and is compared with uniform heat generation case. This work provides the basis for a comprehensive investigation of the influence of nonuniform heat generation.     

Slope protection by membrane structures

Left uncontrolled the effects of weathering can lead to severe degradation of slopes. To assess these effects a field trial has been carried out involving both protected and unprotected slopes. In this trial two types of slope protection were investigated. The first was a simple synthetic mat installed directly over the exposed surface of the slope. The second was a more substantial geotextile reinforced fill facing, incorporating fillow bushes which generate root systems to aid long-term stability of the protective facing. Data are presented to show that appropriate protection systems do prevent significant deterioration in the slope. Also the combination of a geotextile and deep rooting vegetation produce robust structures which are able to withstand high loadings with acceptable deformations. The use of a geotextile reinforced protection system is illustrated through two examples. These show that protection of the face of fill slopes can be achieved either by encapsulating the fill in the geotextile reinforcing layers or by the use of a three-dimensional wire netting applied directly to the face.     

Trace elements in precipitation over an industrial area of Bombay

An extensive rainwater sampling program was carried out in the Chembur Trombay industrial belt of Bombay to assess the elemental composition of precipitation. The analytes included Hg, Cr, Sb, Pa, Fe, Sc, Sm, La, Eu, As, Co, Zn, Na, K, Ca, Mg, Br and Cl originating from marine, crustal and industrial sources. For comparison, their concentrations at a non-polluted coastal site (Alibag) were also studied. The elemental excesses were determined by calculating the enrichment factors with respect to Sc in the crust, and their probable sources have been examined.     

钢筋剥肋滚轧直螺纹Ⅰ级接头在重庆大剧院的应用

通过钢筋剥肋滚轧直螺纹Ⅰ级接头在重庆大剧院项目的成功应用,介绍了制作钢筋剥肋滚轧直螺纹Ⅰ级接头的关键技术、操作工艺流程、原材料的要求、质量控制措施、检验方法和应用条件.结果表明由于措施到位,确保了钢筋接头质量符合设计及质量验收要求,使工程质量得到了保证.同时Ⅰ级直螺纹连接可运用在工程特殊构件和特殊部位上,且Ⅰ级接头的百分率也不受限制,降低了现场的施工难度.     

Nb双晶中晶界腐蚀与位向差的关系

用干涉显微镜研究了具有对称倾斜晶界的Nb双晶的晶界腐蚀。除了在靠近重合位置点阵(CSL)晶界处出现极小值外,腐蚀深度d是随位向差θ的增大而增加的。对小角度晶界,d随θ的变化遵循Read—Shockley关系。用计算机模拟方法计算了晶界的原子结构及其局部膨胀,用自由体积的变化解释了晶界腐蚀的结构依赖性。     

Verankerung externer Spannglieder an Querträgerscheiben

Anchorage of External Tendons in diaphragms Thoroughly designed anchorage and deviation points are a basic requirement for reliable and durable bridge structures with external prestressing. The behaviour of anchorage constructions can be described by regular strutand‐tie‐models. Similar to previous investigations on corner brackets [1] a design procedure for anchorage diaphragms based on simple equations and diagrams is being derived and applied.     

Removal of emerging contaminants of concern by alternative adsorbents

The effective removal of emerging contaminants of concern (ECCs) such as endocrine-disrupting chemicals, pharmaceutically active compounds, personal care products, and flame retardants is a desirable water treatment goal. In this study, one activated carbon, one carbonaceous resin, and two high-silica zeolites were studied to evaluate their effectiveness for the removal of an ECC mixture from lake water. Adsorption isotherm experiments were performed with a mixture of 28 ECCs at environmentally relevant concentrations (200–900 ng/L). Among the tested adsorbents, activated carbon was the most effective, and activated carbon doses typically used for taste and odor control in drinking water (<10 mg/L) were sufficient to achieve a 2-log removal for most of the tested ECCs. The carbonaceous resin was less effective than the activated carbon because this adsorbent had a smaller volume of pores in the size range required for the adsorption of many ECCs (6–9 Å). For the removal of ECC mixture constituents, zeolites were less effective than the carbonaceous adsorbents. Because zeolites contain pores of uniform size and shape, a few of the tested ECCs with matching pore size/shape requirements were well removed, but the adsorptive removal of others was negligible, even at zeolite doses of 100 mg/L. The results of this study demonstrate that effective adsorbents for the removal of a broad spectrum of ECCs from water should exhibit heterogeneity in pore size and shape and a large pore volume in the 6–9 Å size range.