Non-complete relief method for measuring surface stresses in surrounding rocks

The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter（d）, the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth（h） were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.     

合成生物学在生物基塑料制造中的应用

合成生物学是以工程学思想为指导,对天然生物基因组进行改造和重构,合成新的生物元件,构建新的代谢途径,生产新产品或获得新表型的新兴学科。生物基塑料是以天然物质为原料在微生物作用或化学反应下生成的塑料。利用合成生物学改造工程菌株的方法制备合成生物基塑料已经成为学术界和产业界关注的热点。本文综述了合成生物学的发展和重要的合成生物学技术,重点综述了利用合成生物学技术构建聚羟基烷酸酯、尼龙、聚乳酸和丁二酸丁二醇酯等生物基塑料聚合物单体及其衍生物的代谢途径和工程优化领域的研究进展。     

微生物法处理含硫工业废气

指出了含硫工业废气传统处理方法的缺陷 ,介绍了微生物处理方法的优势所在 ;对微生物菌种的共同特征以及无机硫和有机硫脱除时菌种的选择依据进行了讨论 ,并对微生物法脱硫的机理进行了分析 ;评述了国内外生物滤池法、生物滴滤池法和生物吸收法等生物膜法脱硫的工艺及其工业化应用。指出了微生物法脱硫技术有待深入研究的问题、发展趋势和应用前景。     

应变影响下单晶Ge薄膜热导率分析

利用非平衡态分子动力学模拟方法研究了应变对Ge薄膜热导率的影响。结果表明系统应变对单晶Ge薄膜热导率产生明显影响,热导率随着拉伸应变的增大而减小,随着压缩应变的增大而增大,得出声子速率降低以及薄膜表面重构是产生该模拟结果的内在原因。同时,采用修正的Callaway模型对NEMD结果进行理论验证,两种方法得到的结果吻合得较好。理论结果表明应变弛豫时间对Ge单晶薄膜的热导率产生了重要影响。     

Electron beam welding of aluminium alloy by wire feed method (1st Report).Effect of filler wire melting configuration on bead formation

The 5XXX series of non-heat-treatable aluminium alloys, widely used in modern industry, have the peculiarity that an area near the welding bead, which reaches a temperature higher than 230°C, suffers an annealing effect that causes a considerable decrease in yield strength. The present paper deals with the three-dimensional modelling, using general-use finite element software, of a classic experiment conducted in the past by Masubushi, using the GMAW process on aluminium alloy 5052 H32, in order to determine the thermal history, and transient and residual strain and stress. Finally, a method for modelling applicable to this material type is proposed, where the model is divided into three zones; one near the weld with the properties of aluminium in annealed state, another further away with the base metal properties, and a transitional zone with intermediate properties.     

Bi-templated grain growth maximizing the effects of texture on piezoelectricity

Templated grain growth is beneficial for piezoelectric materials, the properties of which become the best in their single crystalline form. Nevertheless, a textured ceramic prepared by a templated grain growth technique often fails in exhibiting as good properties as expected in single crystals even with a high degree of orientation factor. Here, we propose a new strategy for maximizing texturing effect by suppressing the growth of untextured matrix grains. The textured ceramics made by our method, so-called bi-templated grain growth, are featured by ultrahigh piezoelectric properties (d₃₃ = ～1,031 pC/N, d?g = ～59,000, k_p = ～0.76). A special emphasis is on the achieved electric-field-induced strain of 0.13 % at 1 kV/mm, which is as high as that of single crystals. This work demonstrates that not only the degree of texture but also the coarsening of untextured matrix grains should be well-controlled to best exploit the templated grain growth technique.     

Coupled buckling and plastic instability for tube hydroforming

In this paper, the hydroforming limit of isotropic tubes subjected to internal hydraulic pressure and independent axial load is discussed.Swift's criterion is often used in this case for the prediction of diffuse plastic instability. Here, we first highlight the existence of two different Swift's criteria (for sheets and for tubes).Then, we recall that these types of approaches do not take into account buckling induced by axial loading. In fact, buckling may obviously occur before plastic instability; consequently, Swift's criteria must not be used alone to predict instability in the case of tube hydroforming.Numerical simulation was used to confirm these points and to analyse both the buckling and striction phenomena together. The two types of instability must be treated together in a reasonable approach to the hydroforming process.In this paper, the material verifies a “J2-flow” constitutive rate constitutive law. Jaumann's derivative was chosen and the Prandtl–Reuss equations with von Mises’ yield criterion and the associated flow rule were used. Isotropic hardening was taken into account.     

阿魏菇多糖高产菌株筛选的离子束诱变和复合诱变对比研究

为筛选出阿魏菇菌丝体多糖高产菌株,本文进行了阿魏菇多糖高产菌株筛选的离子束诱变和复合诱变对比研究。尝试用打散的阿魏菇菌丝体为靶材,以离子束注入为诱变手段,通过营养缺陷型初筛和摇瓶发酵复筛,获得了2株阿魏菇多糖高产菌株PFPH-1和PFPH-2。其菌丝体多糖产量分别达到551．80mg,L和659．46mg／L,比出发菌株分别提高了46．55％和75．14％。再分别以PFPH．1和PFPH．2为出发菌株,用紫外线和氯化锂进行复合诱变处理,通过高通量初筛和摇瓶发酵复筛,结果发现,菌株1、9和10号比其出发菌株PFPH-1的多糖产量分别减少了27％、38％和37％;菌株17号比其出发菌株PFPH-2的多糖产量减少了28％。在本研究中,紫外线和氯化锂的复合诱变表现出了一定的负效应。     

An Analysis of the Curling Phenomenon in Viscoelastic Bimaterial Strips

A mathematical analysis is performed to obtain relations for the radius of curvature and flexural moments for initially stretched bimaterial strips in which at least one of the materials exhibits viscoelastic behavior. One practical application of this analysis is for pressure sensitive tapes. Consequently, the radius of curvature and flexural moment relations are obtained as functions of backing and adhesive thicknesses and moduli for typical pressure sensitive tapes. The analysis shows that the flexural moment decreases as the backing thickness and/or backing modulus increase. Furthermore, the flexural moment decreases as the adhesive thickness and/or adhesive modulus decreases.