新型液压破碎锤的研究

在分析国内外现有液压破碎锤工作原理的基础上首次提出一种可以无级调节冲击能和冲击频率的新型液压破碎锤，并对它进行了计算机仿真研究，同时通过样机进行了大量的实验研究。实践证明，该液压破碎锤具有结构简单、冲击能和冲击频率可无级调节，节能，维修方便等优点。     

гЖум—295型泡沫潜孔锤简介

介绍了俄罗斯гЖум－295型泡沫潜孔锤，对其结构和工作过程作了详细的阐述，并分析了其局限性。     

Transient Friction in Pressurized Pipes. I: Investigation of Zielke’s Model

This paper investigates the well-known model for unsteady friction developed by Zielke in 1968. The model is based on weights of past local bulk accelerations and is analytically correct for laminar flow, but computationally demanding. Different models have been proposed using dynamic properties, typically based on instantaneous accelerations (IAB) that are more rapid in computational schemes. Unfortunately, they are not as accurate as Zielke’s model and fail to model certain types of transients. This paper points out that the water hammer transient is dominated by a periodicity varying along the pipe. Because of this, the unsteady friction calculated by the Zielke model is distributed nonuniformly along the pipe, and changes in the pipe length change the local unsteady friction. This phenomenon may explain why IAB models using calibrated coefficients to match experimental results have a large span in value for the reported coefficients. This paper will hopefully contribute to further work to find highly accurate and rapid models. The subject deserves to be brought up for discussion as a part of a total understanding of the problem.     

Transient Friction in Pressurized Pipes. II: Two-Coefficient Instantaneous Acceleration–Based Model

The goal in the field of modeling of hydraulic transients is a comprehensive model for pipe networks that is computationally fast and accurate. The fastest models are the one-dimensional (1D) models that use instantaneous acceleration–based (IAB) properties, but unfortunately these models are not as accurate as the more demanding 1D convolution-based (CB) models or quasi two-dimensional models. Focusing on a single pipe, this paper investigates the fundamental behavior of the much more accurate 1D CB model to find two coefficients for use with the two-coefficient formulation of the much-used modified IAB (MIAB) model for complete closing of a downstream valve. Two coefficients are found based on the weighting function used in the CB model, and these coefficients vary along the pipe length. Simulations are compared with two experimental results from tests performed at University of Adelaide in Australia in 1995. The experimental results are for different initial Reynolds numbers of approximately 2,000 and 5,800. The results show very good agreement between simulations and experiments. The improvement of the MIAB model is not general, and for the time being, only complete closure of a downstream valve in a single pipeline at low Reynolds numbers has been investigated.     

采用吊垂式拉伸试验机探讨超塑性变形速度的提高方式

在吊锤式拉伸试验机上研究了2024铝合金在自由延伸过程中每个时期的应变速度与显微组织的变化,发现经过恒速应变后,金属的超塑性变形会出现应变速度不断加快,实际应变速度比恒速应变速度可提高1.25个数量级.并提出:材料在低温、高应变速度下难以获得理想的超塑性效果;在提高超塑性成形速度的同时,适当升高变形温度,可使工件超塑性恒温锻造的应变速度提高8～10倍.     

电影机片盒喷涂氨基锤纹漆

介绍了电影机片盒的涂装前处理、工艺流程;讨论了喷涂氨基锤纹漆的工艺参数、施工要点、漆膜质量及产生漆膜弊病的原因。     

RESEARCH ON THE CONDITION TO SET A TAILRACE SURGE TANK

When using the draft-tube vacuum to be less than 8. 0m as the rule to set a tailrace surge tank, a mixing function that describes the process of water-hammer vacuum and velocity-head vacuum varied with time is proposed, on the assumption that the guide vane of the hydraulic turbine and the turbine discharge were all changed linearly. An exact maximum of the draft-tube vacuum for the first-phase waterhammer and the last-phase water-hammer is obtained. Finally a much more reasonable formula of critical tailrace length is derived. The results of two cases show that the formula proposed can determine correctly and reasonably whether a tailrace surge tank is needed or not, and are more suitable for project design than the formula suggested by the specification.     

梅龙供水加压泵站停泵水锤防护设计

介绍一种大流量高扬程远距离输水加压泵站设计中停泵水锤防护措施。     

重力重夯加固地基施工技术

介绍了重力重夯加固地基的特点、适用范围及工艺原理，从施工准备、桩位及标高控制等方面，就其工艺流程作了阐述，并结合具体工程实例，指出此法加固地基效果良好，技术可行。     

四锤头精锻机研发工作的现状调查

通过对全国现有四锤头精锻机的调查研究，阐述了精锻机在特种钢材锻造中的地位和优势，提出对精锻机国产化的研究开发和投资的建议。