连续桥梁上无缝线路伸缩附加力的分析与计算

在总结既有文献计算结论的基础上,综合分析实际测试结果的数据,应用桥梁、钢轨相互作用原理及计算模型,分析了铁路连续梁桥有碴轨道上铺设无缝线路情况下,钢轨伸缩附加力的作用机理及分布规律。     

合同缔约过失责任分析

缔约过失责任制度是基于诚实信用原则对合同缔约过程中产生的信赖利益给予救济的法律制度,是民法学一项重要的研究课题,本文拟对缔约过失责任的法律基础、认定要素,其与违约责任和侵权责任的区别,结合一些学者的观点作相应浅显分析。     

Is There a Curse of Dimensionality for Contraction Fixed Points in the Worst Case?

This paper analyzes the complexity of the contraction fixed point problem: compute an ε‐approximation to the fixed point V*Γ(V*) of a contraction mapping Γ that maps a Banach space B_d of continuous functions of d variables into itself. We focus on quasi linear contractions where Γ is a nonlinear functional of a finite number of conditional expectation operators. This class includes contractive Fredholm integral equations that arise in asset pricing applications and the contractive Bellman equation from dynamic programming. In the absence of further restrictions on the domain of Γ, the quasi linear fixed point problem is subject to the curse of dimensionality, i.e., in the worst case the minimal number of function evaluations and arithmetic operations required to compute an ε‐approximation to a fixed point V*∈B_d increases exponentially in d. We show that the curse of dimensionality disappears if the domain of Γ has additional special structure. We identify a particular type of special structure for which the problem is strongly tractable even in the worst case, i.e., the number of function evaluations and arithmetic operations needed to compute an ε‐approximation of V* is bounded by Cε^−p where C and p are constants independent of d. We present examples of economic problems that have this type of special structure including a class of rational expectations asset pricing problems for which the optimal exponent p1 is nearly achieved.     

互动性电视新闻评论节目介入特征探析——基于《新闻深一度》的个案分析

以《新闻深一度》为例,从对话扩展和对话压缩两个方面对互动性电视新闻评论节目的介入特征进行探讨。在对话扩展上,《新闻深一度》具有众多参与者通过多媒体方式使用引发资源、问句式引发资源多分布于主持人话语和画外音中、摘引资源多出现在画外音中的特征;在对话压缩上,该栏目具有否定资源多分布于嘉宾话语中、对立资源多出现在主持人话语和画外音中、一致资源只出现在主持人话语中的特征。     

我国农林学科研究生教育动态数据平台建设研究

本文分析了我国研究生教育动态数据管理的特点和现状,主要从数据著录规范的制定,数据采集的对象、类型和原始数据的处理以及平台系统研发技术和系统功能模块的实现,研究我国农林学科研究生教育动态数据平台的建设。     

用压缩映射原理证明常系数线性常微分方程组解的存在性与唯一性定理

为了证明高阶常系数线性常微分方程组解的存在性与唯一性定理，首先把它化为一阶常系数线性常微分方程组，又把一阶方程组化为积分方程组，再利用压缩映射原理，证明积分方程组有且只有一组解．     

成渝城市群城市收缩的空间格局与形成机制研究

文章利用第五次和第六次人口普查数据,以成渝城市群16座地级及以上城市行政单元为研究对象,对其收缩的空间格局、基本特征和形成机制展开全方位的测算和分析。结果显示：（1）成渝城市群16座地级及以上城市中有13座出现收缩现象,占城市总量的81.25%,主要集中于成渝城市群中部地区;3座处于非收缩状态,占城市总量的18.75%,重点分布于城市群两侧边缘;14个市辖区出现收缩现象,约占市辖区总量的29.79%;64个市辖县出现收缩现象,约占市辖县总量的65.98%。（2）收缩城市总体可以划分为全域式收缩、边缘式收缩和局部式收缩三种主要类型,其中全域式收缩主要包括5座城市,约占收缩城市总量的38.46%,均位于成渝城市群中部地区,且呈现连绵化发展趋势;边缘式收缩主要包括4座城市,约占收缩城市总量的30.77%;局部式收缩主要包括4座城市,约占收缩城市总量的30.77%,主要分布于成渝城市群的中部边缘地区,非收缩的市辖区（县）被收缩的城镇所包围。（3）少年儿童和劳动年龄人口减少的同时老龄人口不断增加,社会抚养负担持续加大;人口受教育程度呈现持续上升趋势,本科及以上学历人口占比均出现大幅度增加;第一产业就业人口占比出现大幅下滑,二、三产业就业人口占比则大幅上升,且第二产业就业人口占比上升幅度最大。（4）通过对城市收缩的形成机制分析,中心城市的虹吸效应、产业结构转换中的就业岗位不足、人口老龄化趋势加重、自然因素,以及政府适当的干预构成成渝城市群城市收缩的关键性机制。     

转型抑或收缩：山西票号对辛亥革命的因应

山西票号不完全是辛亥革命的"承受体",对革命的因应是透视其兴衰轨迹的关键。作为革命策源地,汉口票帮在武昌起义前已面临严重的市场风险和经营考验。市场环境方面,汉口的金融恐慌仍在延续,而票号的业务重心已从汇兑转向存放款,这意味着稍有不慎,卷入了钱庄业务链条的票号即面临放款无法收回的窘境。经营状况方面,受外部环境影响,票号数量总体上呈动态减少的趋势,经营业绩更是直线下降。武昌起义爆发后,汉口深陷动荡,在汉票号通过与山西总号的互动,着力解决票据账簿的保存、业务的收缩和调整以及债权债务的清理等问题。然而,由于革命的突发性强,外加长程通信导致的信息滞后,总号始终难以拿出有效的应对方案,分号实际拥有了自主处理本埠号务的权限。在这一过程中,票商面对严重的社会失范,更倾向于维护既有的经济社会秩序。这种诉求根源于其因应政治革命时的不利地位,即分号被迫收撤或迁址,金融运转被强行中断,造成大量坏账、呆账,尤其是当票商欲通过各方力量防止挤兑风潮和倒账危机的举措收效甚微时,其与新政府之间的信任隔阂也随之扩大。票商的因应机制充分证明,辛亥革命没有导致票号的根本衰亡,由政权鼎革所加剧的自身经营压力和动荡政局重塑了票号此后的发展路径,集中体现在民国初年票商拒绝金融转型的态度以及"缩小主义"的经营策略。在转型与收缩之间,票商理性而审慎地选择了后者,所谓错过合组银行的"历史机遇"不过是后来者对历史发展情境的理想预设。     

Existence and Uniqueness of Solutions to the Bellman Equation in the Unbounded Case

We study the problem of the existence and uniqueness of solutions to the Bellman equation in the presence of unbounded returns. We introduce a new approach based both on consideration of a metric on the space of all continuous functions over the state space, and on the application of some metric fixed point theorems. With appropriate conditions we prove uniqueness of solutions with respect to the whole space of continuous functions. Furthermore, the paper provides new sufficient conditions for the existence of solutions that can be applied to fairly general models. It is also proven that the fixed point coincides with the value function and that it can be approached by successive iterations of the Bellman operator.     

Bayesian inverse problems with heterogeneous variance

We consider inverse problems in Hilbert spaces under correlated Gaussian noise, and use a Bayesian approach to find their regularized solution. We focus on mildly ill-posed inverse problems with fractional noise, using a novel wavelet-based vaguelette–vaguelette approach. It allows us to apply sequence space methods without assuming that all operators are simultaneously diagonalizable. The results are proved for more general bases and covariance operators. Our primary aim is to study posterior contraction rate in such inverse problems over Sobolev classes and compare it to the derived minimax rate. Secondly, we study effect of plugging in a consistent estimator of variances in sequence space on the posterior contraction rate. This result is applied to the problem with error in forward operator. Thirdly, we show that empirical Bayes posterior distribution with a plugged-in maximum marginal likelihood estimator of the prior scale contracts at the optimal rate, adaptively, in the minimax sense.