Effect of Rare Earths on Corrosion Resisting Properties of Carbon-Manganese Clean Steels

Rareearthelementshavesignificantactionsinsteels ,includingwipingoffimpurityelements ,trans modifyinginclusions ,andimprovingmicrostructureetal,soaddingappropriaterareearthsintosteelscanef fectivelyimprovetheircorrosionresistingproper ties[1,2 ] .Todaypuri…     

Modeling and analysis of workpiece stability based on the linear programming method

After being located on a machine bed, a workpiece will be subject to gravity and cutting forces during the machining operation. In order to keep the locating precision as well as the production safety, it is necessary to maintain the workpiece stability. In this paper, a linear programming method is proposed for stability analysis of the workpiece. Based on the linear approximation of the friction cone, a quantitative criterion is established to verify the workpiece stability in association with the rationality of the clamping sequence, magnitude of clamping forces and clamping placement. This criterion allows designers to plan reasonably the clamping sequence, magnitude of clamping forces as well as clamping placement. Compared with existing methods, the main advantage of this approach lies in that the sophisticated computing of contact forces between fixture elements and the workpiece is avoided. In this work, both friction and frictionless cases can be easily taken into account in stability analysis. Mathematical formulations of the method are given and some numerical tests are finally demonstrated to validate the proposed method.     

环境美学视野中的山水城市理念

从阐述宜居城市的内涵出发,提出乐居是宜居的最高境界,并进而在此基础上,透过环境美学的视野,分析了山水城市理念与城市乐居追求的内在关联,指出环境美学试图营造的让人乐居的理想居住环境,实际上与山水城市的理念殊途同归．     

福建连城锰矿在困境中求发展

通过分析近几年制约矿山发展的因素,提出了一系列克服困难的对策,值得多数矿山借鉴。     

双能X线吸收法与近红外法测定脂肪含量的评价

用美国Ｌｕｎａｒ ＤＰＸ－Ｌ骨密度仪和日本ＦＶＴＲＥＸ－１０００型近红外仪对９２例人群进行脂肪含量评价。其中７８例为健康人，男性４３例，女性３５例。测定结果女性平均脂肪含量高于男性，两种方法对全部人群的体脂肪测定结果相关系数ｒ＝０．９２１，本文介绍测定原理并对两种方法的优缺点作了评价。     

中国参考人系列模型的建立及外照射剂量学特征的研究

为探讨不同人种、不同姿势及新的组织权重因子对人体剂量学的影响,建立了基于GBZ/T200的中国参考人系列模型（包括立姿、坐姿、走姿的男女模型）;结合蒙特卡罗程序计算得到不同射线能量、6种标准照射方式下的器官吸收剂量和有效剂量。结果表明,基于不同权重因子和不同种族参考模型可得到不同的有效剂量,尤其是低能阶段的差异较为明显;姿势的改变使得器官剂量和有效剂量有所变化,主要由于器官之间的屏蔽作用,体现在相对立姿时坐姿前后照射的有效剂量减小和走姿左右照射的有效剂量增加。进行辐射剂量学评估时,在低能阶段不同的影响因素对结果有较大的影响,而高能时不太明显,因此在进行医学影像等复杂辐射场的辐射防护工作时应注重实际情况的考虑。     

Nitrogen utilization and transformation in red soil fertilized with urea and ryegrass

The influence of fertilization with urea and ryegrass on nitrogen utilization and transformation in red soil has been studied by using ^15N tracer method.When urea and ryegrass were applied alone or in combination,the percentage of N uptaken by ryegrass from labelled urea was 3 and 1.7 times that from labelled ryegrass for the application rate of 200mgN.kg^-1 and 100mgN.kg^-1,respectively;combining application of ryegrass and ureareduced uptake of urea N and increased uptake of ryegrass N by ryegrass plant,but the percentage of N residued in soil increased for urea and decreased for ryegrass.when urea and ryegrass were applied alone,the percentage of N residued in soil from labelled ryegrass was more than 69% while that from labelled urea was less than 25%,and much more ryegrass N was incorporated into humus than urea N.     

血液中铀的测定与探讨

本工作采用裂变径迹技术测定人体血液中的微量铀,血样品直接从健康者、从事铀研究的工作者和白血病患者的手指中取样(20μl),试图确定人体血液中微量铀的统计分布。实验测得健康者血液中微量铀的平均值为(3.06±0.10)×10~(-10)g/ml;从事铀工作者血液中微量铀的平均值为(4.53×0.12)×10~(-10)/ml;而白血病患者血液中微量铀的平均值为(7.74±0.15)×10~(-10)g/ml,是健康者2.5倍。所提供的方法灵敏度高、采血量少,对铀矿工作者职业保护有实用意义,并为寻找理想的解毒和促排药物提供可靠的依据。     

EnGAN：医学图像分割中的增强生成对抗网络

原始采集的医学图像普遍存在对比度不足、细节模糊以及噪声干扰等质量问题,使得现有医学图像分割技术的精度很难达到新的突破。针对医学图像数据增强技术进行研究,在不明显改变图像外观的前提下,通过添加特定的像素补偿和进行细微的图像调整来改善原始图像质量问题,从而提高图像分割准确率。首先,设计引入了一个新的优化器模块,以产生一个连续分布的空间作为迁移的目标域,该优化器模块接受数据集的标签作为输入,并将离散的标签数据映射到连续分布的医学图像中;其次,提出了一个基于对抗生成网络的EnGAN模型,并将优化器模块产生的迁移目标域用来指导对抗网络的目标生成,从而将改善的医学图像质量知识植入模型中实现图像增强。基于COVID-19数据集,实验中使用U-Net、U-Net+ResNet34、U-Net+Attn Res U-Net等卷积神经网络作为骨干网络,Dice系数和交并比分别达到了73.5%和69.3%、75.1%和70.5%,以及75.2%和70.3%。实验的结果表明,提出的医学图像质量增强技术在最大限度保留原始特征的条件下,有效地提高了分割的准确率,为后续的医学图像处理研究提供了一个更为稳健和高效的解决方案。     

茶叶样品中微量元素分析方法的研究

采用HNO3-H2O2混合酸,密闭微波消解制样,ICP—AES、ICP—MS测定茶叶中P、Zn、Fe、Mn、Mg、Ca、B、Cr、Co、Ni、Cu、Mo、Cd、Pb等14种微量元素含量,建立了对植物样品中多种元素进行同时测定的方法。经国家植物标准物质验证,方法具有较好的准确性和重现性,操作流程短,检出限低,基体干扰小,RSD≤10％,加标回收率在90％～110％之间。可用于植物样品的批量分析。