竹坑水库大坝安全鉴定分析

在竹坑水库大坝安全鉴定中,认真分析了该工程存在的主要问题,并针对大坝的结构稳定和渗流稳定作了详细的分析论证.     

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本文应用灰色关联分析方法,对70种不同类型和组成的钻井液,进行了两参数流变模式优选及评价。与现行方法比较的结果表明此方法与现行结果的吻合度高,并有新颖、数据要求量少、结论易于比较等优点。     

激光在塑性变形测量中的应用

本文将激光应用于云纹法，研究了缺口滚压强化后根部区域的位移场及应变分布规律。结果表明，本方法是提高塑性变形测量精度的有效手段。     

Energy absorption in splitting square metal tubes

This paper presents an investigation into the energy absorbing behaviour of axially splitting square metal tubes. Tubes 50 mm square with a variable thickness were pushed slowly against rigid pyramid shaped dies, which had various semi-angles. By pre-cutting 5 mm long slits at the four corners, the tube splits along the corners and curls outward with a certain radius at a constant force. In this energy dissipating system, there are three components: tearing energy, plastic deformation energy and frictional energy. Theoretical analysis of the three energy components is presented. Curl radius is also studied in detail. Good agreement between experiments and theory is obtained. The results show that tubes which both split and curl may be used as efficient, long stroke energy absorbing devices.     

Effect of thermomechanical treatment on mechanical properties and electrical conductivity of a CuCrZr alloy

The CuCrZr alloy undergoes processes of precipitation during ageing. Besides precipitation hardening the strength is affected by cold deformation which is performed before and after ageing. The cold deformation (D ₁) before ageing accelerates the process of strength hardening, since it induces higher rate of precipitation from the saturated a-sold solution. Cold deformation (D ₂) after ageing primarily affects the alloy strength. In this paper the results of the effect of thermomechanical treatment on mechanical properties and electrical conductivity of a CuCrZr alloy are presented. The aim of the paper was to evaluate the most suitable combination of thermomechanical treatment and alloy properties.     

混凝土简支梁预设变形值探讨

以某高速公路钢筋混凝土与预应力混凝土工程为例，从简支梁的预拱度和下挠度的设置两方面进行了阐述，提出了钢筋混凝土简支梁下挠变形和预应力混凝土简支梁上拱变形的不同之处。     

碎丝埋弧焊在大型立式储罐中的应用

大型储罐底板焊接及变形控制是保证储罐整体施工质量的关键环节,采用碎丝填充的焊接方法可以防止变形,同时可以有效地避免应力集中,提高施工质量。文章介绍了碎丝埋弧焊的原理、工艺参数和焊接方法。实践证明,填充碎丝不仅是一种减小底板焊接变形的手段,同时可以充分利用焊接热能,节约焊接时间和焊剂用量,经济效益好,是一种值得推广的技术。     

"Temporal encoding in fear conditioning revealed through associative reflex facilitation": Correction to Lindquist and Brown (2004).

Reports an error in "Temporal Encoding in Fear Conditioning Revealed Through Associative Reflex Facilitation" by Derick H. Lindquist and Thomas H. Brown (Behavioral Neuroscience, 2004[Apr], Vol 118[2], 395-402). The article contained several errors. On page 396, second paragraph, the sentence beginning on line 6 should read as follows: "Having a stable baseline is critical for studies of reflex facilitation because the experimental designs invariably entail repetitive CR testing, if only to achieve reasonable statistical power (see Choi et al., 2001b; Lindquist & Brown, 2004)." On page 400, the first heading should read as follows: "Comparison of New and Old Reflex Facilitation Procedures." On page 400, the first sentence under the abovementioned heading should read as follows: "We decided not to use the original measure of reflex facilitation, developed by J. S. Brown et al. (1951), because it suffers from severe interpretational limitations, elaborated in detail elsewhere (Choi et al., 2001b; Leaton & Cranney, 1990; Lindquist & Brown, 2004)." (The following abstract of the original article appeared in record 2004-12681-016.) Temporal encoding in Pavlovian fear conditioning was examined through conditional facilitation of the short-latency (Rl) component of the rat eyeblink reflex. Rats were fear-conditioned to a tone conditional stimulus (CS) with either a 3- or 9-s interstimulus interval (ISI) between CS onset and the onset of the grid-shock unconditional stimulus (US). Rl facilitation was tested over 2 days, in counterbalanced order, at a latency of 3 s and 9 s from CS onset. CS-produced Rl facilitation, the conditional response (CR), was 3-4 times larger when the test latency equaled the conditioning ISI. These results, coupled with the known neurophysiology of Rl facilitation, suggest that this CR could disclose differences in the time course of CS-generated output from the amygdala when driven by cortical versus subcortical CS-CR pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Defect structure of gold introduced by high-speed deformation

The effect of deformation speed on defect structures introduced into bulk gold specimens at 298 K has been investigated systematically over a wide range of strain rate from ′=10⁻² to 10⁶ s⁻¹. As strain rate increased, dislocation structure changed from heterogeneous distribution, so-called cell structure, to random distribution. Also, stacking fault tetrahedra (SFTs) were produced at anomalously high density by deformation at high strain rate. The anomalous production of SFTs observed at high strain rate is consistent with the characteristic microstructure induced by dislocation-free plastic deformation, which has been recently reported in deformation of gold thin foils. Thus, the results of the present study indicate that high-speed deformation induces an abnormal mechanism of plastic deformation, which falls beyond the scope of dislocation theory. Numerical analysis of dislocation structure and SFTs revealed that the transition point of variation of deformation mode is around the strain rate of 10³ s⁻¹.     

紧凑式轧机变形规程优化设计

本文从紧凑式轧机的轧制变形特点出发,分析了其变形规程设计的主要特点和方法,讨论了限制其道次变形量的基本因素,给出了优化设计的目标函数和约束条件。指出,类似这种具有复杂约束的轧制变形问题采用混合罚函数法处理更为有效,并成功地采用该方法进行了变形规程的试设定。