小冲杆测试材料屈服载荷的有限元分析

文章通过ABAQUS有限元分析软件模拟小冲杆试验过程,重点分析2.25Cr1Mo、16MnR、20#、1.25Cr0.5Mo4种材料的小冲杆屈服载荷。试验结果表明,有限元模拟得到的材料屈服载荷与常规拉伸试验所得出的屈服强度存在显著的线性关系,并具有相当高的相关系数。为最终通过小冲杆试验评价材料的屈服强度提供了一条新的思路。     

Ti－48at％Al合金PST晶体的高温压缩性能

采用磁悬浮区域熔炼的方法制备了ＴｉＡｌ合金ＰＳＴ晶体，然后在８００℃下对其压缩性能和变形组织分别进行了测试和观察。结果表明，在８００℃时的屈服强度取决于片层界面与压缩轴的夹角φ在φ＝９０°时屈服强度最高，而φ＝４５°时最低。８００℃时屈服强度较室温下的有较大程度下降，这与α２相中锥面滑移系｛１１２１｝＜１１２６＞的临界分切应力的降低有关．     

工艺参数对合成ZnO／Ag纳米复合抗菌剂产率的影响

通过正交实验，研究了反应温度、反应时间、反应物配比对ZnO／Ag纳米复合抗菌剂合成产率的影响规律。获得了高产率合成ZnO／Ag纳米复合抗菌剂的优选工艺条件：反应温度为10～25℃，ZnSO4与NH4HCO3的摩尔比为1：2-2．5，ZnSO4与NH4HCO3的反应时间为2．5～3h，AgNO3与NH4HCO3的摩尔比为1：1．5～2，反应时间为0．5h，ZnO／Ag的产率超过98％。XRD、TEM和SAED结果表明：ZnO／Ag纳米复合抗菌剂为具有纤锌矿结构的ZnO和立方结构的Ag组成。粒径为15～25nm，分散性较好。     

The preparation of tantalum powder using a MR-EMR combination process

In the conventional metallothermic reduction (MR) process used to obtain tantalum powder in batch-type operation, it is difficult to control the morphology and location of the tantalum deposits. In contrast, an electronically mediated reaction (EMR) process is capable of overcoming this difficulty. It has the advantage of being a continuous process, but has the disadvantage of a poor reduction yield. A process known as the MR-EMR combination process is able to overcome the shortcomings of the MR and EMR processes. In this study, an MR-EMR combination process is applied to the production of tantalum powder via sodium reduction of K₂TaF₇. In the MR-EMR combination process, the total charge passed through an external circuit and the average particle size (FSSS) increase as the reduction temperature increases. In addition, the proportion of fine particles (−325 mesh) decreases as the reduction temperature increasess. The tantalum yield improved from 65 to 74% as the reduction temperature increased. Taking into account the charge, impurities, morphology, particle size and yield, a reduction temperature of 1123 K was found to be optimum for the MR-EMR combination process.     

各向异性屈服准则的发展及应用

各向异性是影响板料成形的重要因素之一。在板料成形的有限元模拟中，正确描述板料的各向异性行为有助于提高模拟精度。近年来，人们对板料的各向异性屈服行为进行了深入研究，研究内容主要有屈服准则的提出、实验验证及其在有限元模拟中的应用3个方面。本文总结了各向异性屈服准则的理论研究及实验验证的发展现状，以及各向异性屈服准则在板料成形有限元模拟软件中的应用，最后提出了各向异性屈服准则研究中今后的研究方向。     

超声振动对石蜡铸坯凝固的影响

为了探索不同条件下使用超声振动对改善钢坯凝固组织结构的作用,试验对不同浇注温度、时间下有无超声振动的水冷凝固石蜡铸坯进行了对比研究,得到较低温度(62℃以下)时超声冷却对改善铸坯内部结构有很好的效果,但减小了收得率;浇注温度为72℃时,超声作用更多体现在搅拌石蜡液芯上,提高了铸坯的收得率,作用时间长时(20min)可以改善铸坯内部结构。     

某城区排涝泵站设计流量计算方法初探

采用平均排除法、最大24 h雨型洪水流量时程分配法和产流汇流法3种方法分别计算了某城区电排站的设计流量,并将3种方法的计算结果进行对比分析,选用合适电排站的设计流量,可为类似工程设计流量的确定提供参考。     

木头峪水源地廊道取水允许开采量计算

简要分析了廊道的水流特征,通过引入等效渗透系数,构建廊道取水的渗流-管流耦合模型,并用之于陕北佳县木头峪水源地廊道取水工程,确定了开采方案,同时计算了开采方案枯水期廊道取水的允许开采量,最终确定木头峪地下水廊道开采方式允许开采量为16 900 m3/d。建立的廊道取水数学模型能较好地反映廊道的水流特征。     

Correlation of slurry reactor Fischer-Tropsch yield data

First stage slurry reactor Fischer-Tropsch (FT) yield data from Mobil's two-step pilot plant operations for the DOE have been correlated using a modified Schulz-Flory approach but allowing for changes in the probability of chain growth, , at key product molecular weights. Triple values of are invoked to explain (1) the high methane yield and (2) the very broad molecular weight distribution of the wax fraction, as compared to (3) moderate values of ₂ of between 0.79 and 0.85 for the C₂–C₂₀ hydrocarbons. Over this range, wax yields from 10 to 76 wt% are accommodated, at values of ₃ from 0.90 to 0.98. The second break in the yield-molecular weight curve occurs at the carbon number where most of the component remains in the reactor as liquid rather than leaving as vapor product. It is assumed that this is a function of vapor-liquid equilibrium. The correlation has proven useful in developing a computer model of the FT synthesis loop which is part of a baseline design and economic study for DOE/PETC.     

A NEW BATO COMPLEX^99mTcCl（4—MCDO）3MeB FOR MYOCARDIAL IMAGING

A new nertral complex,^99mTcCl(4-MCDO)3MEB,((Bis[4-methyl-1,2-cyclohex-anedionedioximato(1-)-O]-[4-methyl-1,2-cyclohexanedione-dioximato(2-)-O] methyl-borato(2-)-N,N‘,N″,N‘‘‘,N‘‘‘‘0-chlorotechnetium,generally called BATO(Boronic acid adducts of technitium dioximes),has been synthesized and evaluated for potential use in myocardial perfusion imaging,It has intrinsic affinity for the blood clearance.The uptake of heart.lung and blood in mice at 2min separately are 1.12,2.48 and 6.66%ID.The complex formation is rapid,simple and highly yielded(≥93%).This process is easy to kit formation.