Effect of polycarboxylate-type superplasticizer on the paste fluidity based on the water film thickness of flocs

The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity.The theory states that excess water can surround the flocs rather than the particles and that the cell consists of a floc and a superficial water film.Experiments on limestone powder pastes were conducted to verify the theory.The superplasticizer dosage(sp%)and the water–powder ratio by volume(Vw/Vp)were systematically varied.A sedimentation balance method was used to measure the size distribution of the flocs in the limestone powder pastes.The water film thickness(WFT)of flocs was then calculated and shown to determine the paste fluidity.Based on this WFT of flocs,the effect of the sp on the paste fluidity was determined and then compared with the effect of water.     

水平井完井方式优选

本文详述水平井完井方式选择的一般步骤,包括井壁稳定性及出砂判断的数学模型、考虑了多种因素对完井方式选择的影响。     

水下长隧道最小安全顶板厚度研究

根据轴线地质剖面和隧道轴线布置图,对某拟建中水下公路隧道最小安全顶板厚度的确定进行了研究,通过比较得出最合理的最小安全顶板厚度,对同类工程有很大的参考价值。     

离子束溅射淀积光学薄膜的膜厚均匀性实验

介绍了离子束溅射技术改善薄膜均匀性的两种方法。研究了修正板技术,根据工程需要将修正板技术应用于行星转动条件下的光学薄膜的均匀性修正。分别研究了靶摆动和不摆动的情况下,淀积薄膜的均匀性修正。实验结果表明,修正后的均匀性结果优于 1%,能满足实际应用的要求;靶摆动修正的均匀性结果优于修正板技术。     

细粒砂金选收研究

为选收细长、密实、不规则的细粒砂金，保证其在分选中的有效重力大干介质阻力，应制定以跳汰为基础的船选工艺和先分级、后分选的岸上选厂工艺，优选适宜矿砂各自特性的选矿设备和操作参数．恰当地应用旋流器、人造草皮和毛毯等．也可有效地捕收细粒砂金．     

系统动力学在累积环境影响评价中的应用研究

文章分析了利用系统动力学 (SD)方法进行累积影响评价的能力 .实例研究表明 ,SD方法能较好地反映环境影响的动态变化过程 ,在空间累积效应的评价方面也有一定作用 ,是进行累积影响评价的有效方法     

工业炸药有毒气体含量测定的影响因素

文章探讨了工业炸药爆炸后有毒气体测定过程中多种因素对测定结果的影响。试验表明,钢炮扩孔对有毒气体测定结果影响明显,随钢炮扩孔增大,有毒气体含量显著增大。当扩孔率为37%和95%时,有毒气体总量比新钢炮分别增大了24.5%和29.2%。起爆用雷管对低感度炸药有毒气体测定结果影响较显著,而对高感度炸药影响较小;用军用雷管起爆产生的有毒气体最少,而用煤矿许用瞬发电雷管起爆产生的有毒气体最多,并且膨化硝铵炸药有毒气体的增加(23.0%)大于粉状乳化炸药(10.8%)。石英砂用量对有毒气体测定结果也有明显影响。当石英砂完全覆盖药卷时,在一定范围内,增加石英砂用量导致有毒气体含量增大;当钢炮扩孔相当大时,增大石英砂用量使钢炮口全部覆盖严实,有毒气体含量减少。     

The Role of the Choroid in Stargardt Disease

Stargardt disease is the commonest juvenile macular dystrophy. It is caused by genetic mutations in the ABCA4 gene. Diagnosis is not always straightforward, and various phenocopies exist. Late-onset disease can be misdiagnosed with age-related macular disease. A correct diagnosis is particularly critical because of emergent gene therapies. Stargardt disease is known to affect retinal pigment epithelium and photoreceptors. Many studies have also highlighted the importance of the choroid in the diagnosis, pathophysiology, and progression of the disease. The choroid is in an integral relationship with the retinal pigment epithelium and photoreceptors, and its possible involvement during the disease should be considered. The purpose of this review is to analyze the current diagnostic tools for choroidal evaluation and the extrapolation of useful data for ophthalmologists and researchers studying the disease.     

新建350MW超临界机组典型缺陷分析及处理

分别对呼和浩特热电厂扩建的2台350 MW超临界空冷火力发电机组在基建监督检查中发现的锅炉、汽轮机和四大管道等主要设备存在的承重部件焊缝裂纹、未熔合,P91材料集箱开裂及内壁氧化严重,P91材料集箱硬度异常,集箱内部存在大量异物,弯管壁厚减薄超标,大型铸件及径向支撑轴瓦等缺陷的产生原因及可能对机组安全、稳定运行造成的影响进行了分析,并采取了相应的补焊、重新加工处理及更换等措施,为保证机组投运后的安全稳定运行奠定了基础,并为开展超(超)临界火力发电机组的基建监督检查工作提供参考。     

LUBRICATION FILM FORMATION MECHANISM OF SLIPPER PAIRS IN LOW SPEED HIGH TORQUE HYDRAULIC MOTORS

Pressure-flow analytical formulas of lubrication film of slipper pairs on camshaft connect- ing rod type low speed high torque (LSHT) hydraulic motors are put forward. The bottom surface of slipper pairs is rectangle, and the effect of squeeze flow and pressure differential flow is considered. The dynamic process of lubrication film formation through squeezing is numerically studied by com- puter simulation. Effects of supply pressure, initial lubrication film thickness, velocity damping coef- ficient, loading impact and gravity, etc are studied. Advantages of novel slipper pairs with large oil cavity area are pointed out.