Elastic labor supply and agglomeration

This study analyzes the interplay between the agglomeration of economic activities and interregional differences in working hours, which are typically longer in large cities, as they are normally more developed than small cities. For this purpose, we develop a two‐region model with endogenous labor supply. Although we assume a symmetric distribution of immobile workers, the symmetric equilibrium breaks in the sense that firms may agglomerate when trade costs are intermediate and labor supply is elastic. We also show that the price index is always lower, while labor supply, per capita income, real wages, and welfare are always higher in the more agglomerated region.     

城镇化对农业农村的多维度影响——基于省际面板数据实证研究

基于面板数据，从综合系统-子系统-要素等三方面定量测度省域人口、土地与产业城镇化对农业农村发展的影响程度，深入剖析城镇化不同要素对农业与农村系统发展的作用机理。研究结果表明：①人口城镇化与产业城镇化对农业农村的影响更加明显，对农村生活系统影响的弹性系数大于1的地区比重分别为58.06%和64.52%；土地与产业城镇化对农业生产系统产生负向影响较为明显，弹性系数小于0的地区比重分别为29.03%和38.71%；②城镇化率、产业结构和建成区比重对人均耕地面积、乡村劳动力比重和人均粮食产量呈显著负相关，与农民人均纯收入、人均农业产值和单位面积机械动力呈显著正相关；③通过深入分析近30年省域城镇化对各地区农业农村发展的作用机理，对于新时期新型城镇化、农业农村转型发展等战略的贯彻落实具有重大的现实意义。     

交通区位演化与空间开发强度的时空协同关系及其弹性识别——重庆市案例实证研究

交通区位条件是反映区域发展潜力的重要指标,分析其与空间开发强度之间的时空协同关系对揭示区域发展的动力机制具有重要启示意义。以重庆市为例,通过指数建模、回归拟合及弹性系数等方法,揭示其间互动关系。研究发现：①研究区交通区位指数处于快速跃升阶段,区域差距有所缩小,空间集聚格局基本稳定;②空间开发强度指数数值整体偏低,增速差异较大,空间集聚格局呈单集聚中心向多集聚中心演进趋势;③不同类型的交通区位指数（内部、外部和综合）与空间开发强度指数均呈显著正相关,且关联性表现出不同状态;④交通区位演化与空间开发强度互动敏感程度较高,各弹性系数空间集聚格局基本一致,但其形成机理差异较大。     

需求弹性对产业活动的指示功能研究

需求弹性对产业活动有很强的指示功能。围绕需求弹性不同的商品的需求(量)对经济变量的依存关系,研究如何运用需求弹性指导产业活动行为有重要意义。本文概述了需求弹性的数学基础,结合需求弹性释义,从价格弹性、需求收入弹性和交叉(价格)弹性等方面讨论了需求弹性对产业活动的指示功能。     

Structural Integrity of Stone Blocks From Charles Bridge in Prague

The Charles Bridge is the oldest, still-standing gothic bridge that crosses the Vltava River in Prague and up to now has belonged among the most sought-after historical monuments in the Czech Republic. The bridge has been repeatedly damaged due to floods and has been repaired several times. In the reconstructions, damaged sandstone blocks were substituted in facing. This experimental study focused on nonlinear ultrasonic spectroscopy for testing stone blocks that were extracted from the historical bridge structure. The objective of these experiments was verifying whether the methods can be applied to evaluating the internal structure of blocks, which are built-in in the structure in situ. Intact-structure blocks, blocks that had been repaired in the past, and damaged-structure blocks were measured. Two methods of nonlinear ultrasonic spectroscopy were applied—the method with single harmonic ultrasonic signal and with two harmonic ultrasonic signals. Measurement results of both applied methods proved resulting parameters correlation with block structure integrity quality.     

基于能量方法的江浙地区抬梁式及穿斗式传统民居木构件重要性分析

为研究中国传统木构建筑的结构构件重要性排序问题,以江浙地区抬梁式和穿斗式两种典型的传统民居木结构类型为研究对象,基于能量方法采用构件属性改变后对结构整体应变能的单位体积改变率作为构件重要性的评价指标,运用有限元软件Ansys(16.0)开发了基于生死单元法和改变弹性模量法的构件重要性评价程序。分析结果表明,改变弹性模量法更适用于中国传统木构建筑的结构构件重要性分析。通过对抬梁式和穿斗式的单榀框架和整体框架在竖向荷载、水平地震荷载两种工况下的结构构件重要性的计算分析,得到了构件的重要性系数和排序,并提取出了抬梁式和穿斗式传统木构的关键构件。研究结果可以为确定传统木构建筑遗产在修缮施工、维护以及结构健康监测过程中需要重点关注的构件提供科学合理的理论依据。     

ELASTIC EARTH PRESSURES ON RIGID WALLS UNDER EARTHQUAKE LOADING

Elastic dynamic earth pressures induced by earthquakes are computed by analyzing a wall-foundation-backfill system. Both foundation and backfill are considered viscoelastic; the foundation is a semi-infinite space and the backfill, a uniform layer of constant thickness. A simple analytical solution is developed by assuming an approximate backfill-foundation interface condition and adopting the least squares method. The response functions computed indicate the large influence of the various system parameters on earth pressure, including the foundation characteristics,as well as wall geometry and mass. The transient response of the system is also studied by obtaining spectra for base shear. A large number of seismic records are analyzed to obtain average spectra and a total of three correction functions are used to take into account the foundation stiffness and density as well as wall inertia. A simple design method is proposed to estimate the maximum base shear.     

RESPONSE OF UNREINFORCED MASONRY BUILDINGS

Abstract

A summary of dynamic measurements are presented that illustrate relations between linear seismic demand and true nonlinear response of unreinforced masonry buildings with flexible diaphragms and rocking piers subjected to a series of simulated earthquake motions.     

Investigation of coupled hydraulic–geomechanical processes at the KTB site: pressure‐dependent characteristics of a long‐term pump test and elastic interpretation using a geomechanical facies model

The German Continental Deep Drilling Program comprising a pilot borehole down to 4000 m and a main borehole down to 9101 m in southeast Germany (KTB) is continuing to provide a unique opportunity for the identification of important factors and processes in deep‐seated fluid and energy transfer. In situ stress conditions significantly impact flow, transport and exchange characteristics of fracture networks that dominate the permeability of crystalline reservoir rocks. In this paper, several scales of information are combined to present a fully three‐dimensional hydraulic finite element model of the principal KTB fault zones, and linked to a geomechanical model describing the alteration of the hydraulic parameters with stress changes caused by fluid extraction. The concept of geomechanical facies is introduced to define and characterize architectural elements in the subsurface system. Evaluation of a long‐term pump test in the KTB pilot hole, June 2002–July 2003, coupled with a geomechanical model gives an insight into some of the elastic and nonelastic processes controlling hydraulic transport in the basement rocks. Trends in the decline of the permeability and the degree of storage in the system could only partially be explained by elastic processes, clearly indicating the importance of nonelastic processes. A number of inelastic processes are suggested as areas for further research.     

基于荷载修正的传统木构建筑构件重要性分析方法研究

传统木构建筑的构件重要性对于整体结构状态的评估具有重要意义,为弄清楚传统木构建筑的构件重要性,开发了一种基于荷载修正的传统木构建筑构件重要性评价程序,基于荷载工况修正与荷载重分布修正重构了荷载分布矩阵,基于荷载施加构件修正改进了构件重要性计算方法。以典型传统木构建筑——保国寺大殿为例进行了数值模拟分析,并基于广义刚度评价了构件重要性,分析了各项修正对构件重要性的影响情况以及最终修正对构件重要性的结果变化率。结果表明:柱类构件的修正变化为-0.526%~2.192%;梁栿类构件的修正变化为-2.638%~50.598%;铺作类构件的修正变化为-12.763%~9.989%;槫类构件的修正变化为-7.586%~6.918%。保国寺大殿构件重要性排序:柱类>槫类>梁栿类>铺作类;修正后柱类、梁栿类重要性提高,铺作类、槫类重要性降低。可为传统木构建筑的结构状态评估和预防性保护提供参考。