贵州红层地区危岩带变形破坏机制及防治研究

危岩体(崩塌)是贵州红层地区具有典型的代表性的地质灾害。本文以元厚镇危岩带为例,深入分析元厚镇危岩带的破坏特征及形成机制。将红层地区危岩带的变形破坏机制概括为3个阶段,总结贵州红层地区危岩带破坏特点,并提出了有针对性的综合治理措施。     

Variable Selection via Generalized SELO-Penalized Cox Regression Models

The seamless-L_0(SELO) penalty is a smooth function that very closely resembles the L_0 penalty, which has been demonstrated theoretically and practically to be effective in nonconvex penalization for variable selection. In this paper, the authors first generalize the SELO penalty to a class of penalties retaining good features of SELO, and then develop variable selection and parameter estimation in Cox models using the proposed generalized SELO(GSELO) penalized log partial likelihood(PPL) approach. The authors show that the GSELO-PPL procedure possesses the oracle property with a diverging number of predictors under certain mild, interpretable regularity conditions. The entire path of GSELO-PPL estimates can be efficiently computed through a smoothing quasi-Newton(SQN) with continuation algorithm. The authors propose a consistent modified BIC(MBIC) tuning parameter selector for GSELO-PPL, and show that under some regularity conditions, the GSELOPPL-MBIC procedure consistently identifies the true model. Simulation studies and real data analysis are conducted to evaluate the finite sample performance of the proposed method.     

The Convergence of Least-Squares Progressive Iterative Approximation for Singular Least-Squares Fitting System

Data fitting is an extensively employed modeling tool in geometric design. With the advent of the big data era, the data sets to be fitted are made larger and larger, leading to more and more leastsquares fitting systems with singular coefficient matrices. LSPIA (least-squares progressive iterative approximation) is an efficient iterative method for the least-squares fitting. However, the convergence of LSPIA for the singular least-squares fitting systems remains as an open problem. In this paper, the authors showed that LSPIA for the singular least-squares fitting systems is convergent. Moreover, in a special case, LSPIA converges to the Moore-Penrose (M-P) pseudo-inverse solution to the leastsquares fitting result of the data set. This property makes LSPIA, an iterative method with clear geometric meanings, robust in geometric modeling applications. In addition, the authors discussed some implementation detail of LSPIA, and presented an example to validate the convergence of LSPIA for the singular least-squares fitting systems.     

高性能膜分离材料、膜过程强化关键技术及装备的研制与应用

针对影响和制约膜分离技术大规模推广应用的关键材料与技术瓶颈,中国科学院过程工程研究所"生化工程介质与设备"创新团队经过多年自主创新,在高性能分离膜材料、膜过程强化关键技术和高效膜分离装备等方面取得了系列科研成果,部分成果在调味品、水处理、中药等行业实现了产业化应用,创造了显著的经济效益和社会效益,为提高我国膜工业研发与应用水平,缩短我国膜分离行业与国外先进水平之间的差距,促进膜分离技术的大规模工业化应用做出了贡献。     

青年科技工作者的心理健康状况及影响因素

 青年科技工作者作为科研事业的主力军，承受了更多的工作任务和压力，也面临更多的心理健康风险。为了解青年科技工作者的心理健康状况及影响因素，对中国35岁及以下的青年科技工作者分别在2009年和2017年进行两次大规模调查。研究结果显示：青年科技工作者中有21%存在着不同程度的抑郁表现，47.9%存在不同程度的焦虑问题，11%的青年科技工作者在最近1年中有过自杀意念，青年科技工作者整体心理健康状态呈现下降趋势；青年科技工作者比其他年龄的群体有更多的抑郁倾向和自杀意念，但焦虑水平无显著差异；女性和低学历青年科技工作者有更多的自杀意念，低学历青年科技工作者还有更多的抑郁情绪；婚姻状况、婚姻满意度、情绪调节方式和工作环境均显著影响该群体的心理健康状况。     

医疗卫生工作者心理健康水平现状

 为了解医疗卫生工作者心理健康水平的现状，从2017年科技工作者心理状况调查的数据中选取医疗卫生工作者样本1463人，同时抽取其他科技工作者1441人作为对照组。调查结果发现：医疗卫生工作者抑郁风险低于对照组，焦虑和自杀意念与对照组无显著差异，工作倦怠及情感衰竭度显著高于对照组；医疗卫生工作者心理健康群体差异明显，50岁后抑郁和焦虑水平均降低，正高级职称人群的抑郁和焦虑水平均较低。情绪调控方式上，压制组表现出更多的抑郁和焦虑风险；同时，医疗卫生工作者存在睡眠时间不足、运动次数和运动时长不足、工作时长过长的问题；在心理健康服务方面，医疗卫生工作者整体优于对照组。建议改善医疗卫生工作者工作时长和工作压力，倡导健康生活方式，并提高情绪调节能力。     

用于低层建筑地基的不同长度和掺量椰壳纤维加筋吹填海砂强度参数试验研究

针对海南吹填海砂压实困难、地基承载能力较低的问题,通过直剪试验对椰壳纤维加筋吹填海砂的刚度和抗剪强度进行了研究.结果表明:在吹填海砂中掺入椰壳纤维能够有效提升吹填海砂的力学性能和地基承载力;加筋效果随椰壳纤维加筋土所受垂直应力的增大而增大;椰壳纤维长度小于5 cm时,椰壳纤维对吹填海砂的抗剪强度和刚度随椰壳纤维长度的增大而增大,在椰壳纤维长度达到8 cm时,抗剪强度和刚度反而下降;椰壳纤维加筋土的刚度和最大剪应力一直随椰壳纤维掺量的增大而增大,内摩擦角在椰壳纤维掺量小于0.3%时随掺量增大而增大,当掺量超过0.3%后内摩擦角无明显变化.     

粉末冶金法制备混杂增强铜基复合材料的增强体竞争析出行为研究

Copper matrix composites reinforced by in situ-formed hybrid titanium boride whiskers (TiB_w) and titanium diboride particles (TiB_2p) were fabricated by powder metallurgy. Microstructural observations showed competitive precipitation behavior between TiB_w and TiB_2p, where the relative contents of the two reinforcements varied with sintering temperature. Based on thermodynamic and kinetic assessments, the precipitation mechanisms of the hybrid reinforcements were discussed, and the formation of both TiB_w and TiB_2p from the local melting zone was thermodynamically favored. The precipitation kinetics were mainly controlled by a solid-state diffusion of B atoms. By forming a compact compound layer, in situ reactions were divided into two stages, where Zener growth and Dybkov growth prevailed, respectively. Accordingly, the competitive precipitation behavior was attributed to the transition of the growth model during the reaction process.     

一种改进的分水岭人脑MR图像分割方法

针对传统分水岭算法分割图像后存在的细节不准确问题,提出了一种改进的分水岭算法.此算法将传统分水岭算法和概率相结合,通过有序队列来实现边界的计算,从而得到分水岭.实验证明,这种算法得到的结果更加准确,对人脑MR图像病灶区的分割非常重要.