夏甸金矿崩落法隐伏采空区稳定性分析

采空区是金属矿山重大危险源之一。采空区稳定与否是保证矿山企业正常生产的关键因素之一。夏甸金矿于2003年8月20日开始在-363m水平以下部分矿体采用无底柱分段崩落法进行开采,经10余年的开采,目前已开采至-692m水平,崩落法隐伏采空区的稳定性分析至关重要。利用Surpac建立崩落法开采的矿体模型,进行冒落带高度预测,计算得到冒落带最高点为-251m,并采用FLAC~(3D)程序进行数值模拟,按照矿山回采顺序,共划分12次进行开挖,分析了应力、位移与塑性区破坏规律,变形以采空区上方为中心,呈圆形向外扩展,中心的变形为最大,沉降18cm,采空区边界沉降最小,为4cm。地表沉降位移不大,采空区不会塌陷到地表。     

氨基葡萄糖盐酸盐稳定性及其制备的研究

测定了Ｄ－氨基葡萄糖盐酸盐在酸液中的溶解度及在加热条件下其稳定性，探讨了甲壳素酸水解和甲壳素质量与产品质量、收率之间的关系，对工业化生产Ｄ－氨基葡萄糖盐酸盐的工艺条件优化、质量和收率的提高具有指导意义。     

储层流动单元研究新技术在油田开发中的应用

流动单元研究提供了精细解剖砂体,表征砂体内部非均质性的新方法。本文在传统流动单元划分的基础上应用流动带指标新方法(F z)进行储层流动单元的定量划分,为合理进行油田开发动态分析提供依据,同时开辟了一个可预测可操作的有效流动单元研究方法。     

A Guide to Polysaccharide-Based Hydrogel Bioinks for 3D Bioprinting Applications

Three-dimensional (3D) bioprinting is an innovative technology in the biomedical field, allowing the fabrication of living constructs through an approach of layer-by-layer deposition of cell-laden inks, the so-called bioinks. An ideal bioink should possess proper mechanical, rheological, chemical, and biological characteristics to ensure high cell viability and the production of tissue constructs with dimensional stability and shape fidelity. Among the several types of bioinks, hydrogels are extremely appealing as they have many similarities with the extracellular matrix, providing a highly hydrated environment for cell proliferation and tunability in terms of mechanical and rheological properties. Hydrogels derived from natural polymers, and polysaccharides, in particular, are an excellent platform to mimic the extracellular matrix, given their low cytotoxicity, high hydrophilicity, and diversity of structures. In fact, polysaccharide-based hydrogels are trendy materials for 3D bioprinting since they are abundant and combine adequate physicochemical and biomimetic features for the development of novel bioinks. Thus, this review portrays the most relevant advances in polysaccharide-based hydrogel bioinks for 3D bioprinting, focusing on the last five years, with emphasis on their properties, advantages, and limitations, considering polysaccharide families classified according to their source, namely from seaweed, higher plants, microbial, and animal (particularly crustaceans) origin.     

基于注意力机制的两阶段纵膈淋巴结自动分割算法

判断淋巴结分区是否存在淋巴结转移以及准确分割恶性淋巴结对于肺癌诊断以及治疗意义重大.针对纵膈淋巴结尺寸差异大、正负样本不平衡、与周边软组织和肺肿瘤特征相似等问题,提出了一个新颖的用于纵膈淋巴结分割的基于注意力机制的级联算法.首先,根据医学先验设计了两阶段分割算法剔除纵膈干扰组织后对疑似淋巴结进行分割,减少负样本的影响和...     

规则波中弧形返浪墙的非线性水动力载荷数值模拟

运用基于FLUENT软件平台的二维数值波浪水槽,采用流体体积(VOF)方法处理波浪自由面,应用"解析松弛"方法实现了数值造波-消波。模拟规则波下不同返浪墙断面形式情况下的流场和水动力。应用直墙驻波理论解和物理模型试验结果验证了数值波浪水槽的可行性。比较波浪力的数值模拟与物理模型试验结果可以发现,水动力冲量的均方差小于水动力最大值的均方差,且水动力冲量的误差也小于水动力最大值,说明以冲量作为特征量能更好地描述水动力载荷的变化。在给定堤顶超高的条件下,不同堤脚超高和弧形返浪墙高度的组合对越浪量有明显影响:低弧趾超高和大半径弧面组合有利于降低越浪量,但水动力载荷也较大;高弧趾超高和小半径弧面组合越浪量较大。     

CKD6D型机车转向架的设计

简要介绍了CKD6D型机车转向架的总体布置、主要技术参数和结构特点。     

基于WebGL的3D立库可视化系统设计与实现

针对当前扩大化和普及化的仓储物流,提出了一种3D自动化立体仓库可视化系统的实现方案,用以解决仓储系统中遇到的数据不直观的问题.该系统采用JavaScript编程语言,以Three.js引擎为基础,构建了基于WebGL的三维自动化立体仓库的可视化系统,该系统能有效直观的进行仓储管理,适合现代化仓储企业的管理需求.     

Fracturing behavior of brittle solids containing 3D internal crack of different depths under ultrasonic fracturingOA

Ultrasonic fracturing(UF) can be used to form crack networks for oil or gas in the mining industry and hard rock excavation. In this paper, the three-dimensional internal laser-engraved crack method(3D-ILC) is introduced to make penny-shaped internal crack within the samples without any damage to the surfaces. Physical experiments were performed on the transparent samples with internal cracks at different depths. The macro-and micro-fracture fractography characteristics were focused on and analy...     

数模转换器的EWB仿真分析与研究

为解决实际电子产品设计和开发过程中的问题,以EWB仿真软件为例,详细讨论了D/A数模转换电路和集成DAC芯片的仿真。根据仿真结果得知:温度的影响:当温度从0℃升高到100℃的过程中,输出电压快速升高,最后波动幅度逐渐减小,趋于恒定;电路参数的影响:当R1从1kΩ线性增大到10kΩ,初始输出线性升高,后由于非线性失真趋于恒定,因此设计倒T形电路网络D/A转换器时需注意电阻的精确度。对于集成DAC,当数字输入值较高时转换精度下降。