MSCT多期增强扫描在肾脏透明细胞癌中的诊断价值

目的探讨多排螺旋CT(MSCT)多期增强扫描在肾脏透明细胞癌诊断中的规律性,提高对该肿瘤诊断水平。方法回顾性分析2016年1月~2018年6月14例均经手术切除病理证实为肾脏透明细胞癌患者的CT影像资料,所有病例均行MSCT平扫及多期动态增强扫描。结果14例肾脏透明细胞癌形态大多数呈圆形或者类圆形,瘤体最大径范围1.7cm^11.3cm,平均(4.8±1.4)cm,13例CT平扫时肿瘤密度不均匀,呈等低密度,1例呈等密度;12例出现坏死囊变,钙化1例,伴肾盂、肾盏侵犯2例;动态增强扫描可见12例包膜完整,1例均匀性强化,13例不均匀性强化;引入对比剂后皮质期,出现10例病灶强化幅度大于肾皮质,而仅4例低于肾皮质,三期平均CT值分别为110±30Hu,90±15Hu及75±14Hu,其中在实质期出现13例肿瘤强化幅度小于肾实质,仅1例大于肾实质。结论引入对比剂动态增强扫描后,肾脏透明细胞癌在皮质期明显不均匀强化,实质期强化幅度下降显著,呈现出典型的“快进快出”血流动力学强化方式,且肿瘤容易出现坏死、囊变为其特点。     

覆岩结构类型与开采覆岩损害特征分析

煤层开采打破了上覆岩层原有的平衡,必然引起岩层的移动、破断,导致应力场和裂隙场的改变,工作面出现矿压显现。上覆岩层的岩性和组合结构对工作面开采覆岩损害特征分布影响显著,一般岩性越坚硬,上覆岩层应力集中程度越高,采动裂隙越发育,矿压显现也越明显;坚硬岩层尤其是关键层对覆岩的破断运动起控制作用,覆岩破断发展到一定层位后软弱岩层往往是抑制覆岩破断进一步向上发展的关键。当工作面上覆岩层同时存在远近场关键层时,近场关键层的周期性破断引起裂隙带范围内岩层的运动和工作面周期来压;而远场关键层的周期性破断导致地表裂缝或台阶下沉,工作面压力急剧上升,有时甚至导致煤矿动压灾害,尤其是远近场关键层同步破断时动力现象更明显。通过地面钻孔使远场关键层提前破断是防止此类动力灾害的关键。     

金沙江上游水电站应对白格堰塞湖灾害的措施及经验

2018年10月、11月,西藏自治区昌都市江达县白格村两次发生山体滑坡造成金沙江断流并形成白格堰塞湖,给金沙江上游沿岸人民生产生活设施造成巨大安全威胁和超过百亿元的经济损失。华电金沙江上游水电开发有限公司组织所属企业及参建单位快速应对,采取撤离避让、工程防护、人工干预、生产恢复,推动后续处置、风险评估等措施,最大限度减轻了对金沙江上游叶巴滩、拉哇、巴塘、苏洼龙等在建水电站的灾害损失和后续影响,为类似灾害的处置提供借鉴经验。     

Unsteady free convection of second‐grade nanofluid with a new time‐space fractional heat conduction

The Caputo and Caputo–Fabrizio derivative are applied to study a second‐grade nanofluid over a vertical plate. A comparative analysis is presented to study the unsteady free convection of a second‐grade nanofluid with a new time–space fractional heat conduction. The governing equations with mixed time–space fractional derivatives are non‐dimensionalized and solved numerically, and a comparison between the Caputo and the Caputo–Fabrizio models is made. It is found that the temperature is higher for the Caputo–Fabrizio fractional model than the Caputo model, but the higher velocity only exists near the vertical plate for the Caputo–Fabrizio model than the Caputo model. Moreover, the velocity for the Caputo model will exceed the Caputo–Fabrizio model as y evolves.     

建筑产业转型升级新时代下高职建筑工程技术特色专业建设问题的新思考

随着建筑业技术进步和转型升级,高职建筑工程技术专业建设应顺应新时代要求,产教融合,办出特色。本文提出了“四个对接一个融合”的特色专业建设新思考。     

考虑结构动态变形的缸套-活塞环润滑建模分析

缸套在燃烧冲击和活塞敲击激励下会产生接近表面粗糙度的动态变形,极有可能影响缸套-活塞环组件间的摩擦润滑过程。为了研究缸套动态变形潜在的影响,将动力学仿真获取的缸套内表面的动态变形经过处理后导入到润滑模型中,同时采用数值积分计算的方式对油液压力应力因子和剪切应力因子进行实时计算求解,使仿真计算更加符合实际情况。通过搭建同时考虑缸套变形与油液剪切特性影响的改进润滑模型,计算得到整个工作循环内活塞环上的最小油膜厚度和摩擦力曲线。结果表明:考虑缸套动态变形后的最小油膜厚度和摩擦力曲线出现了明显的波动,而且考虑缸套动态变形后的摩擦力比未考虑之前出现了明显下降。     

Responsive supply in fashion mass customisation systems with consumer returns

Mass customisation systems have been well-established in the fashion industry. Some fashion brands offer the mass customisation system for their selected seasonal products, and allow unconditional returns and full refund for any unsatisfied customers. Motivated by the above mentioned observed industrial practice and based on the growing importance of responsive supply, we explore in this paper the value of quick response supply in fashion mass customisation systems with consumer returns. We focus on investigating how the consumer returns rate affects (i) the optimal inventory decision of the fashion brand, (ii) the achievability of Pareto improvement in implementing quick response supply, (iii) the respective values of quick response for the fashion brand, the fashion supplier and also the fashion supply chain, and (iv) the impact of quick response supply on the environment. We interestingly find that consumer returns enhance the value of quick response supply to the fashion supplier. Quick response supply is also found to be helpful in reducing the environmental cost under the fashion mass customisation system with consumer returns.     

气藏采收率影响因素研究与启示——以靖边气田A井区为例

以鄂尔多斯盆地靖边气田A井区为例，采用单因素相关分析和数值模拟方法，对比研究了井网控制程度、储层物性及地层废弃压力对气藏采收率影响及其主次关系。结果表明，井网控制程度是影响采收率的首要因素，井网控制程度每增加10%，采收率提高8.5%；渗透率是影响采收率的重要因素，渗透率每增加10%，采收率平均增加6%；废弃压力对采收率亦有较大影响，废弃压力每降低10%，采收率可提高1.6%。三者对采收率影响综合排序为：井网控制程度>储层物性>废弃压力。分析认为，渗透率是储层固有属性，很难从根本改变；而废弃压力受井口外输压力和增压开采成本制约，降低幅度有限。因此，优化井网及增加井网控制程度是提高气藏采收率的有效途径。研究成果具有实践意义，可为改进气田开发方式和提高气藏采收率提供参考。     

Measurements of thermal-neutron capture cross-section of Cesium-135 by applying mass spectrometry

ABSTRACT

The thermal-neutron capture cross-section (σ₀) and resonance integral (I₀) were measured for the ¹³⁵Cs(n,γ)¹³⁶Cs reaction by an activation method and mass spectrometry. Because of difficulty in the preparation of pure ¹³⁵Cs samples, we used ¹³⁵Cs contained as an impurity in a normally available ¹³⁷Cs standard solution. An isotope ratio of ¹³⁵Cs and ¹³⁷Cs in a standard ¹³⁷Cs solution was measured by mass spectrometry to quantify ¹³⁵Cs. Cesium-135 impurity along with the ¹³⁷Cs standard solution was irradiated at the hydraulic conveyer of the research reactor in the Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as neutron monitors to measure thermal-neutron fluxes and epi-thermal Westcott’s indices at an irradiation position. A gadolinium filter was used to measure the σ₀, and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of ¹³⁷Cs, ¹³⁶Cs and monitor wires. On the basis of Westcott’s convention, the σ₀ and I₀ values were derived as 8.57 ± 0.25 barn, and 45.3 ± 3.2 barn, respectively. The value of σ₀ obtained in the present study agreed within the limits of uncertainties with the past-reported value of 8.3 ± 0.3 barn.     

王坡煤矿煤层顶板稳定性主控因素分析

煤炭开采过程中极易发生顶板事故。基于王坡煤矿的地质条件，利用钻孔、井下钻探、物探、生产揭露资料，分别对该矿煤层顶板沉积特征、煤层顶板岩石结构特征进行系统分析研究，通过实验室室内测试，获取了煤层顶板岩石抗压强度、泊松比、坚固性系数、黏聚力等物理力学性质指标，最终确定了影响煤层顶板稳定性相关因素；运用层次分析法确定影响因素的权重值，得出岩石力学性质是影响煤层顶板稳定性的主控因素。研究可为类似煤矿顶板稳定性因素分析提供借鉴。