Mutual effects of chemical reaction and thermal radiation on MHD peristaltic transport of Jeffrey nanofluids: Tumor tissues treatment

As thermal radiation is one of the fundamental means of heat transfer, therefore, this study analyzes the impacts of thermal radiation and magnetic field on the peristaltic transport of a Jeffrey nanofluid in a nonuniform asymmetric channel. Further, Two models of viscosity are debated: Model (I), in which all parameters dependent on viscosity behave as a constant (as treated before in nanofluid research); Model (II), in which these known parameters are considered to vary with the temperature of the flow. Under the condition of long wavelength and low Reynolds number, the problem is rearranged. The resulting system of partial differential equations (PNE) is solved with aid of Mathematica 11. Furthermore, the streamline graphs are presented by significance of trapping bolus phenomenon. To emphasize the quality of solutions, comparisons between the previous results and recent published results by Reddy et al. have been made and signified. The comparisons are shown in Table 1 and are found to be in good agreement. As the thermal radiation increases, the diameter of nanoparticles rises (thermal radiation is a diminishing function of temperature, and with a decrease in the temperature, the diameter of the nanoparticles increases, that is, the size of nanoparticles increases and they become more active near malignant tumor tissues). Therefore, its work as agents for radiation remedy, produce limited radiation quantities, and selectively target malignant tumor for controlled mutilation (radiotherapy of oncology). Such a model is appropriate for the transportation of physiological flows in the arteries with heat and mass transfer (blood flow models).     

Numerical study of entropy generation in Darcy-Forchheimer (D-F) Bödewadt flow of CNTs

Three-dimensional Bödewadt flow (fluid rotates at a large enough distance from the stationary plate) of carbon nanomaterial is examined. Single walled and multi walled CNTs are dissolved in water and gasoline oil baseliquids. Darcy-Forchheimer porous medium is considered. Stationary disk is further stretched linearly in radial direction. Heat transfer effect is examined in presence of radiation and convection. Effect of viscous dissipation is accounted. Entropy generation rate is studied. By using adequate transformation (von Kármán relations), the flow field equations (PDEs) are transmitted into ODEs. Solutions to these ODEs are constructed via implementation of shooting method (bvp4c). In addition to Entropy generation rate, Bejan number, heat transfer rate (Nusselt number), skin friction and temperature of fluid are examined through involved physical parameters. Axial component of velocity intensifies with increment in nanoparticles volume fraction and ratio of stretching rate to angular velocity parameter while it decays with higher porosity parameter. Higher nanoparticles volume fraction and porosity parameter lead to decay in radial as well as tangential component of velocity. However it enhances with higher ratio of stretching rate to angular velocity parameter. Temperature of fluid directly varies with higher ratio of stretching rate to angular velocity parameter, radiation parameter, Eckert number, Biot number and nanoparticles volume fraction. Rate of Entropy generation is reduced with higher estimations of porosity parameter, nanoparticles volume fraction and radiation parameter. Skin friction coefficient decays with higher porosity parameter and ratio of stretching rate to angular velocity parameter. Intensification in porosity parameter, nanoparticles volume fraction and Biot number leads to higher Nusselt number. Prominent impact is shown by multiple-walled CNTs with gasoline oil basefluid than single-walled CNTs with water basefluid.     

某企业不同工种的放射工作人员发生甲状腺结节风险分析

采用职业健康体检资料和问卷形式,利用单因素和多因素logistic回归模型,分析探讨某企业内不同工种的放射工作人员暴露在低剂量电离辐射环境下发生甲状腺结节的风险。结果表明,放射工作人员中以混合射线组甲状腺结节发生风险最高,随着年龄和放射工龄的增加发生风险会增加;性别不同与甲状腺结节发生风险有关。     

面向智能客服的句子相似度计算方法

针对金融领域中智能客服的句子相似度计算方法进行了研究。利用基于词性的分词纠正模型减少中文歧义词、金融相关词汇的分词错误；通过词向量方法和循环神经网络分别提取词语级和句子级的语义特征，并且得到句子向量；用融合层计算出句子向量间的差异特征；对差异特征进行降维和归一化得到句子相似度计算结果。实验结果表明，该方法具有较高的准确率和[F1]值。     

医院级CT辐射剂量及诊断剂量水平研究

探讨医院级各部位CT扫描辐射剂量及成人CT检查诊断剂量水平。采集2018年2月—2019年1月本院在GE Light Speed 16 CT设备上进行诊断性CT检查的全部成年人共15 440例的CT检查数据,按照检查部位进行分类,统计各部位的容积剂量指数(CTDI_vol)、剂量长度乘积(DLP)。使用SPSS 19统计软件分析CTDI_vol、DLP的四分位数并计算有效剂量(ED)。结果表明,各部位CTDI_vol的诊断剂量参考水平(DRL)值为:颅脑87.75 mGy、肺部8.09 mGy、上下腹15.82 mGy、上下腹盆腔15.79 mGy;各部位DLP的诊断剂量参考水平(DRL)值为:颅脑1 053.03 mGy·cm、肺部245.19 mGy·cm、上下腹269.96 mGy·cm、上下腹盆腔835.20 mGy·cm。研究中发现肺部CTDI_vol、DLP的DRL值(分别为8.09 mGy、245.19 mGy·cm)低于我国其他地区和其他国家的DRL值;60岁以下患者肺部CT检查CTDI_vol、DLP的DRL值低于8.09 mGy、245.19 mGy·cm,60岁以上患者肺部CT检查CTDI_vol、DLP的DRL值高于8.09 mGy、245.19 mGy·cm。通过研究可以确定医院级各部位CT检查辐射剂量及成人CT检查诊断剂量水平,能为优化CT检查扫描技术和监测辐射剂量提供基础。     

Enzymatic Responses to Low-Intensity Radiation of Tritium

The present study considers a possible role of enzymatic reactions in the adaptive response of cells to the beta-emitting radionuclide tritium under conditions of low-dose exposures. Effects of tritiated water (HTO) on the reactions of bacterial luciferase and NAD(P)H:FMN-oxidoreductase, as well as a coupled system of these two reactions, were studied at radioactivity concentrations ≤ 200 MBq/L. Additionally, one of the simplest enzymatic reactions, photobiochemical proton transfer in Coelenteramide-containing Fluorescent Protein (CLM-FP), was also investigated. We found that HTO increased the activity of NAD(P)H:FMN-oxidoreductase at the initial stage of its reaction (by up to 230%); however, a rise of luciferase activity was moderate (<20%). The CLM-FP samples did not show any increase in the rate of the photobiochemical proton transfer under the exposure to HTO. The responses of the enzyme systems were compared to the ‘hormetic’ response of luminous marine bacterial cells studied earlier. We conclude that (1) the oxidoreductase reaction contributes significantly to the activation of the coupled enzyme system and bacterial cells by tritium, and (2) an increase in the organization level of biological systems promotes the hormesis phenomenon.     

MW级空间核反应堆系统热管式辐射散热器分析及优化

空间核反应堆是空间核电源和核推进的研究基础，大功率核反应堆的体积和质量一直是限制航空航天设计的重要因素。针对这一问题，本文对MW级空间核反应堆系统热管式辐射散热器进行建模和分析，建立热管式辐射散热器的热阻模型，利用穷举法和遗传算法在给定工况下探讨裸碳纤维翅片长度L_f和厚度δ_f、冷却剂质量流量m、辐射散热器入口温度T_f1对散热器质量M的影响。结果表明，当T_f1＝800 K、L_f＝5 cm、δ_f＝0.16 mm、m＝9 kg/s时，M达到最优，为906.593 kg，优化了0.63%的系统质量。     

铁酸镧B位掺Mn/Co/Cr试样的红外辐射性能与机理

采用高温固相烧结法制备了粉体材料LaFeO₃、LaFe_0.75Co_0.25O₃、LaFe_0.75Cr_0.25O₃和LaFe_0.75Mn_0.25O₃，通过XRD、FTIR、SEM、XPS等检测手段对材料进行表征，同时运用CASTEP模块模拟计算了材料的电子能带结构和光学性质。实验结果表明：掺入Mn/Cr/Co离子后晶格发生畸变,晶格对称性降低。Mn/Cr/Co掺杂后的粉体材料在近中红外波段发射率排序为：掺Mn>掺Co>掺Cr>纯LaFeO₃，其中掺Mn在0.2～2.5μm波段为0.8722，2.5～5μm波段为0.6755，远大于纯LaFeO₃的发射率（近中红外波段发射率均为0.5左右）。发射率提升的机理在于：Mn掺杂后,引入了Mn³⁺杂质能级，产生了激活能小的Mn³⁺?Mn⁴⁺跳跃小极化子，电子-氧空位载流子吸收亦增强，同时体系的晶格畸变导致振动吸收加剧。第一性原理计算结果表明掺杂Mn/Cr/Co材料的禁带宽度分别0.793eV、2.406eV、1.722eV均小于纯LaFeO₃的3.817eV，结合态密度计算结果分析其原因，主要Mn3d、Cr3d、Co3d轨道与O2p轨道杂化形成杂质能级，同时Mn3d、Cr3d、Co3d在导带也存在态密度峰，且峰的位置都比LaFeO₃峰更靠近费米能级，作为新的导带底相当于缩短了价带顶到导带底之间的间隙宽度。LaFe_0.75Mn_0.25O₃材料在近中红外波段的优异辐射性能表现，可作为耐高温抗氧化高发射率材料在高温热工炉窑具有潜在应用前景。     

Second order velocity slip and thermal jump of Cu–water nanofluid over a cone in the presence of nonlinear radiation and nonuniform heat source/sink using homotopy analysis method

The purpose of the present paper is to explore the second order slip effects on nanofluid flow over a vertical cone. The effects of nonlinear thermal radiation and nonuniform heat source/sink are also taken into account. Water with copper nanoparticles is used as nanofluid in this investigation. The governing partial differential equations for the flow are converted into ordinary differential equations by using transformations and then are solved using homotopy analysis method. The influence of various important parameters on velocity, temperature, skin‐friction, and Nusselt number are presented through graphs. Results indicate that the velocity and magnitude of skin friction decrease with a rise in first and second order velocity slips. A raise in either first or second order temperature jump causes a fall in temperature. Nonlinear radiation increases the more rapidly when compared to the linear radiation case.