Impact of viscous dissipation and Dufour on MHD natural convective flow past an accelerated vertical plate with Hall current

The present research work concentrates on viscous dissipation, Dufour, and heat source on an unsteady magnetohydrodynamics natural convective flow of a viscous, incompressible, and electrically conducting fluid past an exponentially accelerated infinite vertical plate in the existence of a strong magnetic field. The presence of the Hall current induces a secondary flow in the problem. The distinguishing features of viscous dissipation and heat flux produced due to gradient of concentration included in the model along with heat source as they are known to arise in thermal-magnetic polymeric processing. The flow equations are discretized implicitly using the finite difference method and solved using MATLAB fsolve routine. Numerical values of the primary and secondary velocities, temperature, concentration, skin friction, Nusselt number, and Sherwood number are illustrated and presented via graphs and tables for various pertinent parametric values. The Dufour effect was observed to strengthen the velocity and temperature profile in the flow domain. In contrast, due to the impact of viscous dissipation, the local Nusselt number reduces. The study also reveals that the inclusion of the chemical reaction term augments the mass transfer rate and diminishes the heat transfer rate at the plate.     

Preparation of faceted TaN grains by heating Ta-containing oxides in BN crucible with Na

Single-crystal grains of TaN were synthesized by heating Ta₂O₅, FeTa₂O₆, or FeTaO₄ in a BN crucible together with Na metal in an Ar atmosphere at 1100 °C. The BN crucible acted a solid source of nitrogen. Aggregates of columnar ε-TaN single crystals 10–150 μm in size were formed on the inner wall of the BN crucible when either Ta₂O₅ or FeTa₂O₆ was used. On the other hand, platelet-like single crystals of θ-TaN 1–50 μm in size were obtained from FeTaO₄. The results of wavelength-dispersive X-ray spectrometry indicated that the compositions of the ε-TaN and θ-TaN crystals were close to the stoichiometric ideal.     

光电直读光谱仪在管线钢成分分析中的应用

为了进一步提高SPECTRO LAB直读光谱仪在管线钢成分分析中的准确度和效率，通过参数调整及控样研究，对直读光谱仪分析方法进行了优化，并提出了两种优化方案。结果表明，调整光源参数，能够缩短试验分析时间，减少氩气消耗；综合控样的研究实施，可以解决多块标样分步骤操作的繁琐和误差，省时省力。经实践验证，优化后的方案能够满足生产检验要求，分析方法简单、快捷，降低了成本消耗。     

基于JJG(闽)1086-2018放射治疗CT模拟定位机X射线辐射源的质控分析

整个精确放疗流程最关键、最基础的一个环节就是定位CT扫描精确程度,做好定位CT的质控关乎整个放疗流程的成败。介绍了JJG(闽)1086-2018放射治疗CT模拟定位机X射线辐射源在检定和质控中的流程和方法,从剂量性能要求、图像成像质量和机器机械精度方面对CT模拟定位机的质量控制做了定量的要求。连续8个月的测试结果表明:CT测量值误差在30HU以内,图像均匀性≤5.0HU,空间分辨力7Lp/cm,低对比度分辨力在对比度为1.0%,0.5%,0.3%时分别≤3.0mm,≤5.0mm,≤6.0mm,达到了规程的要求。CT模拟定位机的图像质量和机械精确程度得到了很好的保障,定位CT的剂量准确,影像参数和位置精确度有规可循。     

Design and optimization of radioisotope sources for betavoltaic batteries

A Monte Carlo source model using PENELOPE was developed to investigate different tritiated metals in order to design a better radioisotope source for betavoltaic batteries. The source model takes into account the self‐absorption of beta particles in the source which is a major factor for an efficient source design. The average beta energy, beta flux, source power output, and source efficiency were estimated for various source thicknesses. The simulated results for titanium tritide with 0° and 90° angular distributions of beta particles were validated with experimental results. The importance of the backscattering effect due to isotropic particle emission was analyzed. The results showed that the normalized average beta energy increases with the source thickness, and it reaches peak energy depending on the density and the specific activity of the source. The beta flux and power output also increase with increasing source thickness. However, the incremental increase in beta flux and power output becomes minimal for higher thicknesses, as the source efficiency decreases significantly at higher thicknesses due to the self‐absorption effect. Thus, a saturation threshold is reached. A low‐density source material such as beryllium tritide provided a higher power output with higher efficiency. A maximum power output of approximately 4 mW/cm³ was obtained for beryllium tritide with SiC. A form factor approach was used to estimate the optimum source thickness. The optimum source thickness was found near the thickness where the peak beta particle average energy occurs.     

Biomarker geochemistry of Eq34-10 cyclothem shale in Qianjiang Depression of the Jianghan salt lake facies Basin

The objective of this study is to provide biomarker geochemistry information on shale between sheet-like salts from Qianjiang Depression of the Jianghan salt lake facies Basin, and illustrate the depositional conditions, source organic matter input and maturation. 7 shale samples from Eq3⁴-10 rhythmic were analysed with gas chromatography-mass spectrometry. The investigated biomarkers show that the shale oil are charactertized by an apperent odd-even preference of n-alkane, low Pr/Ph values and a high content of gammacerane and C₃₀+ hopanes, maderate C_21-/C₂₁₊ ratios, the high relative content of C₂₇ 5α(H), 14α(H), 17α(H)- steranes (20R), and an anomaly high C₂₉ sterane ββ/(ββ + αα) value. These biomarker geochemistry characterizations suggested that the shale oils were derived from mixed aquatic organisms and land plants, and deposited in an anoxic and saline-hypersaline depositional environment.     

南海北部神狐海域GMGS1和GMGS3钻探区天然气水合物运聚成藏的差异性

为了探究南海北部陆坡神狐海域GMGS1与GMGS3天然气水合物(以下简称水合物)钻探区的钻探结果存在差异的原因,在分析区域地质背景的基础上,基于高分辨率准3D地震资料,结合实际钻探结果,从"水合物运聚体系"的角度,对上述两个钻探区含气流体运移疏导通道类型、发育演化特点及其对水合物成藏的控制和影响等方面进行了对比研究。结果表明:(1)两个钻探区相距甚近且地质背景相同,但含气流体运移通道类型、组合样式、发育演化特点和运移效能却存在着差异,使得二者气体来源不同;(2)GMGS1钻探区以气烟囱模糊带和中小尺度断层作为主要运聚通道系统,缺乏沟通古近系烃源岩与浅层水合物稳定域的沟源断裂,深部热成因气运移效能低,水合物气源以浅层生物气占绝对优势;(3)GMGS3钻探区靠近白云凹陷东部泥底辟及断层发育区,通道运移效能较高,源自深部古近系烃源岩的热成因气能够通过疑似泥底辟、气烟囱模糊带及断层垂向运移至水合物稳定域,热成因气对其水合物成藏的贡献要大于前者。结论认为,含气流体运聚通道的差异可能是使得上述两个钻探区水合物气体来源及运聚富集程度等出现较大差异的重要原因。     

地面微地震有源噪声自动识别与匹配压制方法

微地震监测技术通过对非常规储层压裂改造引发的震源点进行成像，实时提供压裂施工过程中产生的裂隙高度、长度、宽度和方位角等信息，为致密储层压裂提供指导，以提高油气采收率。在地面布设站点进行监测时，因微地震信号传播距离较远、近地表吸收衰减严重、地面有源噪声较多，微地震数据具有信号能量弱、噪声干扰强和信噪比低等特点，严重制约微地震事件的定位精度。噪声源多分布于地表，根据有源噪声与由储层向上传播的微地震事件在能量、频率、传播速度和源位置等方面的差异，本文提出微地震有源噪声自动识别与匹配方法。综合长短时窗能量比与微地震量板方法，自动识别有源噪声干扰，并进行噪声源位置和传播速度的三维最优并行搜索；利用同时确定的最优噪声源位置和传播速度对微地震数据进行动校正处理，得到噪声标准道，通过能量自适应匹配处理压制有源噪声。正演模拟数据和实际微地震数据去噪效果证明，本文方法能有效压制有源噪声，显著提高微地震数据品质，为后续微地震事件精确定位奠定了基础。     

基于声源定位的高校在线巡课系统设计与研究

随着网络建设以及信息化教学方法在高校教学过程中的应用普及,越来越多的高校使用在线巡课系统对教师的教学过程进行跟踪和管理,以便发现课堂教学中的亮点、问题和不足。文章提出的在线巡课系统,基于声源定位的技术,对传统的在线巡课系统做出了改进,解决了已有巡课系统中“只闻其声,不见其人”的问题,能够更直观地跟踪到教师的教学过程,包括教学行为以及师生互动过程,有效提升教务人员巡课效果和体验感受。     

渤中凹陷西南部烃源岩TOC含量预测

烃源岩总有机碳（TOC）含量是评价有机质丰度的主要指标。地球化学方法的岩心测试仅能获得离散的TOC含量数据，难以实现烃源岩的三维定量评价。结合地球物理测井方法和地震叠前反演方法，针对渤中凹陷西南部陆相深层烃源岩，通过岩石物理交会分析优选对TOC含量敏感的弹性参数，建立TOC含量与纵波速度、密度的地震反演模型；使用拓展ΔlogR方法和地震叠前反演方法分层计算渤中凹陷西南部东营组和沙河街组烃源岩TOC含量，获得TOC含量曲线和TOC含量三维反演体，进而计算东二下段、东三段、沙一二段、沙三段烃源岩TOC含量地震预测平面图。结果表明预测误差较小，证明了该方法的可靠性。研究区烃源岩非均质性较强，总体呈现“层系多、分布广”的特征。东营组烃源岩北部优于南部，且东三段TOC含量值总体高于东二下段；沙河街组TOC含量值整体较高，为研究区的主力烃源岩层，TOC含量呈现自沉积中心向外逐渐降低的趋势，尤以沙一二段A、B、C、E井区及其附近区域、沙三段A、C井区及其西部、南部部分地区TOC含量值最高，具有良好的生烃潜力。