设计素描的四种基本功

设计素描作为学习设计的一门基础课程,通过观察方法、思维方式、表现形式、立体观念和细节刻画四个方面的介绍说明设计素描对于学习产品设计的重要性.     

跨学科比较与中国古典文学研究

跨学科比较虽属比较文学研究方法,但在中国古代文学研究领域有着广泛的应用前景,中国古代的泛文学观念、文史哲不分的传统以及文学和艺术的密切关联,为跨学科比较提供了宽广的用武之地,故自2 0世纪80年代以来得以迅速发展,成为这一时期古代文学研究的重要现象。倘能结合古代文学研究的实际需要对该方法加以变通灵活应用,相信有助于更好地认识古代文学的整体特性和对具体文学现象作更深入的考察     

偏微分积分方程的周期边值问题

本文用上下解方法结合特征线理论讨论了形如 U_t+f(t,x)U_x=g(t,x,u,Tu) u(0,x)=u(2π,x) (1)的一阶偏微分积分方程解的存在性与唯一性,进而用双边迭代的方法给出其求解的程序。     

具有卖空总量限制的多阶段M—SAD投资组合优化

文章提出具有卖空总量限制、阈值约束和V型交易成本的多阶段均值—半绝对偏差（M-SAD）投资组合优化模型。该模型分别运用均值和半绝对偏衡量资产的收益率和风险。由于交易成本的存在,该模型不满足无后效性的动态优化问题。文章将该模型近似为一般动态规划问题,提出一种新的离散迭代方法,并证明该算法是线性收敛的。最后,文章通过实证研究比较分析卖空总量限制和风险偏好系数取不同值时对投资组合最优策略的影响,验证模型和算法的有效性。     

我国养老机构空间布局特征及其优化

基于ArcGIS软件,运用空间分析法,从公平性和均衡性视角,对全国31个省市（不包括港澳台地区）养老机构的空间布局特征展开研究,探究我国养老机构整体发展历程与演化特点,并利用改进的两步移动搜索法对各县域养老机构的空间可达性进行测算。结果表明：我国养老机构的发展历程可划分为萌芽期（1949—1977年）、增长期（1978—1998年）、规范期（1999—2008年）和建设期（2009—2020年）四个阶段,各阶段具有不同的分布特征;养老机构总体区域分布差异较大,主要集中在东部和中部地区,而西部地区较为分散,供给水平尚未达到预期目标值;我国养老机构空间分布出现多个聚集核心,布局总体呈“品字形”分布,密度由聚集中心向周边地区逐渐递减;按规模划分有效服务半径评价养老机构的空间可达性更为有效,我国东南部地区的可达性明显优于西北部地区,西北部多数为可达性低值区,养老机构资源配置有待进一步完善。     

紧密型县域医共体政府监管的问题探析和对策研究

紧密型县域医共体(简称紧密型医共体)是我国现阶段进一步深化医药卫生体制改革、落实分级诊疗制度的重要路径和关键举措。文章基于紧密型医共体的监管现状,以史密斯模型理论为框架,从政策目标、执行机构、目标群体和外部环境四个方面对紧密型医共体的监管困境及问题进行剖析。结果显示,政策目标模糊、执行机构协调性不足、经济与技术环境作用有限等因素一定程度上影响了紧密型医共体监管效果。针对存在问题,应完善监管政策体系、明确执行主体权责、促进目标群体参与、优化社会技术环境来推动紧密型医共体的高质量发展。     

复调和函数的混合边值问题

利用Ｆｏｕｒｉｅｒ方法得到复调和函数的混合边值问题解的表示式及解的存在性定理并讨论了解的唯一性．     

Application of Markov chain Monte Carlo methods to modelling birth prevalence of Down syndrome

Data collected before the routine application of prenatal screening are of unique value in estimating the natural live-birth prevalence of Down syndrome. However, much of these data are from births from over 20 years ago and they are of uncertain quality. In particular, they are subject to varying degrees of underascertainment. Published approaches have used ad hoc corrections to deal with this problem or have been restricted to data sets in which ascertainment is assumed to be complete. In this paper we adopt a Bayesian approach to modelling ascertainment and live-birth prevalence. We consider three prior specifications concerning ascertainment and compare predicted maternal-age-specific prevalence under these three different prior specifications. The computations are carried out by using Markov chain Monte Carlo methods in which model parameters and missing data are sampled.     

曲线箱梁桥实用设计方法的研究

曲线箱梁桥目前还缺乏比较实用的设计方法．本文对曲线箱梁桥的现有设计方法作了研究，并推荐一种实用设计方法：采用空间梁单元，每个节点取六个自由度；等效梁格的模拟考虑了横向梁格附近有无横隔梁的情况．结果证明，这是一种简便、较精确的设计方法．     

On the Effect of Probability Distributions of Input Variables in Public Health Risk Assessment

A central part of probabilistic public health risk assessment is the selection of probability distributions for the uncertain input variables. In this paper, we apply the first-order reliability method (FORM)^(1–3) as a probabilistic tool to assess the effect of probability distributions of the input random variables on the probability that risk exceeds a threshold level (termed the probability of failure) and on the relevant probabilistic sensitivities. The analysis was applied to a case study given by Thompson et al. ⁽⁴⁾ on cancer risk caused by the ingestion of benzene contaminated soil. Normal, lognormal, and uniform distributions were used in the analysis. The results show that the selection of a probability distribution function for the uncertain variables in this case study had a moderate impact on the probability that values would fall above a given threshold risk when the threshold risk is at the 50th percentile of the original distribution given by Thompson et al. ⁽⁴⁾ The impact was much greater when the threshold risk level was at the 95th percentile. The impact on uncertainty sensitivity, however, showed a reversed trend, where the impact was more appreciable for the 50th percentile of the original distribution of risk given by Thompson et al. ⁴ than for the 95th percentile. Nevertheless, the choice of distribution shape did not alter the order of probabilistic sensitivity of the basic uncertain variables.