煤矿采动区地面井逐级优化设计方法

为进一步优化煤矿采动区地面井设计方法,对地面井的类型及特点进行了深入分析,将煤矿采动区地面井抽采技术细分为邻近层采动发展区地面井抽采、本煤层采动发展区地面井抽采和采动稳定区地面井抽采3种类型;确定了抽采资源评估、布井位置优选、井型结构优化、高危位置防护、地面安全抽采等5项核心技术,提出了不同类型采动区地面井的逐级优化设计方法。将系统化的技术方法应用在了山西晋煤集团成庄煤矿5310工作面采动区CD-01井的优化设计和抽采工程中,获得了连续抽采、抽采体积分数50%以上的良好抽采效果,证明了逐级优化设计方法及技术的适用性。     

On the fabrication of functional graded 3Y-PSZ/316L materials by SPS: Process optimization and characterization of the obtained products

Dense and crack free six-layered functional graded materials were successfully produced by Spark Plasma Sintering by combining 3 mol% Y₂O₃-partially stabilized ZrO₂ (3Y-PSZ) and 316L stainless steel. All the sintered products consisted of a steel free layer on one side and a cermet composite containing 50 vol% of both constituents on the opposite side. Conversely, the stainless steel concentration in the interlayers was progressively changed following diverse spatial profiles.It was found that the temperature interval from 1080 to 1180 °C required for the full consolidation from the 50 vol% composite layer to the 3Y-PSZ one, respectively, can be reached when adopting a specific die configuration where the cross section was varied from 30 to 28 mm, respectively. Correspondingly, the densification level of each layer, as well as the related hardness and fracture toughness properties, were highly enhanced with respect to the standard cylindrical die. In addition, a significant improvement of the material toughness was obtained when the material concentration exponent was decreased from 2 to 1, whereas this effect tends to vanish when such parameter was further reduced to 0.5.     

信息安全等级保护现状浅析

信息安全等级保护是我国信息安全建设的一项基本制度，是保障信息化健康发展的重要手段。本文介绍了信息安全等级保护国内外发展历程，以及我国信息安全等级保护的现状，在此基础上，分析了我国等级保护存在的问题，并提出了进一步做好信息安全等级保护工作的建议。     

The effect of tape casting operational parameters on the quality of adjacently graded ceramic film

For small length tape casting of ceramic slurries varying green film thickness is often a problem. To optimise this, the following parameters were investigated: single blade, double blade, using a pump system and a modelled speed change mode have been analysed. Advantages and limitations of every method are described here. The tape casting experiments were built to be generic in order to allow the control of various processing conditions.From these results, the single-blade technique was chosen for a study of side-by-side tape casting. The influence of the geometric parameters of partitioning the casting tank into chambers, on the quality of graded tape was studied. Tape casting experiments at different speeds and partition tongue lengths in combination with rheological tests revealed that high casting speeds and absence of the partition under the blade are detrimental to the formation of the smooth well-controlled interface between the co-cast slurries, required for most of applications.     

Fabrication and characterization of functionally graded Al–SiC nanocomposite by using a novel multistep friction stir processing

Functionally graded materials are one of the most promising candidates among advanced materials. However, some challenges still exist in its fabrication methods. The current study aims to produce functionally-graded bulk Al–SiC nanocomposites by a novel multistep friction stir processing (FSP) for the first time. The SiC nanoparticles were packed into a groove on the 6061 aluminum plate and FSP was performed by using a tool with pin length of 6 mm. Subsequently, FSP was reapplied on another groove by using a tool with a shorter pin length of 3.2 mm. The desirable distribution of SiC nanoparticles in the matrix was confirmed by scanning electron and atomic force microscopes. The composition of graded sample was changed continuously from 18 to 0 wt% SiC along the thickness. Accordingly, the microhardness profile showed a maximum of 160 Hv in the enriched zone which is 3.2 times higher than the hardness of the particle-depleted zone. However, a constant hardness value of 135 Hv was obtained along the thickness of homogenous sample which is 15% lower than that of superficial layer in graded sample. Moreover, the hardness values were linearly correlated with the inverse of interparticle spacing.     

An investigation into the flexural characteristics of functionally graded cobalt chrome femoral stems manufactured using selective laser melting

In order to reduce the stress shielding of the femur following Total Hip Arthroplasty (THA), stiffness matching strategies between the host bone and femoral stem still need to be investigated. Additive Layer Manufacturing (ALM) technologies such as Selective Laser Melting (SLM) can produce components from a single alloy with varying mechanical properties, and hence, functionally graded parts. This work considers the flexural characteristics of laser melted cobalt chrome femoral stems, by using a combination of mechanical testing and finite element analysis. A functionally graded design methodology was considered in order to reduce the weight and stiffness of the femoral stems. Three separate functionally graded designs were investigated by incorporating square pore cellular structures of varying density. The results confirmed that selective laser melting can repeatedly manufacture a functionally graded femoral stem that is 48% lighter and 60% more flexible than a traditional fully dense stem. However, there are concerns associated with the repeatability of the manufacturing process for producing stems with cellular structures that incorporate strut sizes, which are equal to or less than 0.5 mm.     

Frictional contact analysis of functionally graded materials with Lagrange finite block method

Based on the one‐dimensional differential matrix derived from the Lagrange series expansion, the finite block method was recently developed to solve both the elasticity and transient heat conduction problems of anisotropic and functionally graded materials. In this paper, the formulation of the Lagrange finite block method with boundary type in the strong form is presented and applied to non‐conforming contact problems for the functionally graded materials subjected to either static or dynamic loads. The first order partial differential matrices are only needed both in the governing equations and in the Neumann boundary condition. By introducing the mapping technique, a block of quadratic type is transformed from the Cartesian coordinate of global system to the normalized coordinate with eight seeds. Time dependent partial differential equations are analyzed in the Laplace transformed domain and the Durbin's inversion method is applied to determine all the physical values in the time domain. Conforming and non‐conforming contacts are investigated by using the iterative algorithm with full load technique. Illustrative numerical examples are given and comparisons have been made with analytical solutions. Copyright © 2015 John Wiley & Sons, Ltd.     

基于耦合扩展多尺度有限元方法的功能梯度材料热应力分析

以高效模拟功能梯度材料(FGM)微观非均质性对整体热力学性能的影响为研究目的,通过随机形态描述函数(RMDF)法和体积分数的指数分布建立FGM二维微结构,在此基础上,发展了FGM热应力分析的耦合扩展多尺度有限元方法(CEMsFEM)。该方法基于扩展多尺度有限元方法(EMsFEM)的基本思想,对温度场和位移场构造数值基函数,以把微观非均质材料性质带到宏观响应中。同时为了考虑泊松效应导致的不同方向间的耦合作用,在位移场数值基函数中增加了耦合附加项。通过数值基函数建立宏微观单元信息的映射关系,在宏观尺度求解有效方程,节约计算量。为了更好地考虑微观载荷的影响,把结构的真实响应分解为宏观响应和微观扰动,进一步推导出修正的宏观载荷向量。通过不同体积分数分布的FGM在不同载荷工况下的热应力分析算例验证了本文中方法的正确性和有效性,最后讨论了微结构的尺寸效应对结构热力学响应的影响。     

超重力场反应连接制备TiB_2-TiC/1Cr18Ni9Ti和TiB_2-TiC/Ti-6Al-4V梯度复合材料

以1Cr18Ni9Ti、Ti-6Al-4V为金属基底,通过在B4C+Ti体系中引入CrO_3+Al铝热剂,调整反应体系绝热温度依次为3 193、3 282、3 290及3 473K,采用超重力场反应连接制备TiB_2-TiC/1Cr18Ni9Ti和TiB_2-TiC/Ti-6Al-4V梯度复合材料,发现随着反应绝热温度升高,陶瓷/金属界面区厚度不仅因金属熔深增加而增大,并且残存于界面上的Al_2O_3夹杂也随之增多。分别对B4C+Al体系与CrO_3+Al铝热剂进行配制、球磨活化、压制成坯并依次填料入坩埚后,发现残存于界面上的Al_2O_3夹杂完全消除,同时发现在TiB_2-TiC/1Cr18Ni9Ti界面上生成三维网络陶瓷/金属梯度复合结构,而在TiB_2-TiC/Ti-6Al-4V界面上形成跨尺度多层次梯度复合结构。     

Thermoelastic Analysis of Functionally Graded Rotating Disks with Variable Thickness Involving Non-Uniform Heat Source

The research aims to investigate thermoelastic behavior of functionally graded rotating disks with variable thickness involving a non-uniform heat source. We assume material properties and thickness of rotating disks to vary in the radial direction. Axisymmetric thermal loads including non-uniform heat source, heat flux, and temperature boundary conditions are considered. To conduct corresponding simulations, two user subroutines are edited and incorporated into the commercial finite-element code ABAQUS. For verification, analytical formulations are derived and solved uniquely by symbolic calculations using the computing software Mathematica. The developed finite-element technique is then verified with very good agreement between results by ABAQUS and Mathematica.