居民家庭旅游消费行为初探

居民家庭旅游行为是一种特殊的消费行为,本文根据长春市居民家庭消费行为的有关调查资料对影响长春市居民家庭旅游消费行为的因素进行了分析探讨,并说明了居民家庭旅游消费行为研究的重大意义。     

关于中日钓鱼岛争端中"美国因素"的历史考察

文章对中日钓鱼岛争端中的“美国因素”进行了系统考察。二战后美国的日本政策与钓鱼岛问题的产生、发展及变化有着密切联系。在冷战的国际背景下,美国政府通过托管琉球与“第27号令”将中国钓鱼岛纳入其托管之下。20世纪70年代初美国又将钓鱼岛的“施政权”作为冲绳的一部分“归还”给日本,为中日钓鱼岛争端打下“楔子”。冷战结束以来,美国政府在钓鱼岛主权归属上由“模糊中立”到当今小布什政府的“小心介入”,反映了美国政府在钓鱼岛问题立场上的变化。     

Cumulative Ductility Spectra for Seismic Design of Ductile Structures Subjected to Long Duration Motions: Concept and Theoretical Background

A seismic design procedure that does not take into account the maximum and cumulative plastic deformation demands that a structure will likely undergo during severe ground motion could lead to unreliable performance. Damage models that quantify the severity of repeated plastic cycling through plastic energy are simple tools that can be used for practical seismic design. The concept of constant cumulative ductility strength spectra, developed from one such model, is a useful tool for performance-based seismic design. Particularly, constant cumulative ductility strength spectra can be used to identify cases in which low-cycle fatigue may become a design issue, and provides quantitative means to estimate the design lateral strength that should be provided to a structure to adequately control its cumulative plastic deformation demands during seismic response. Design expressions can be offered to estimate the strength reduction factors associated to the practical use of constant cumulative ductility strength spectra.     

Behavior Factor for Performance-Based Seismic Design of Plane Steel Moment Resisting Frames

Simplified expressions to estimate the behavior factor of plane steel moment resisting frames are proposed, based on statistical analysis of the results of thousands of nonlinear dynamic analyses. The influence on this factor of specific structural parameters, such as the number of stories, the number of bays, and the capacity design factor of a steel frame, is studied in detail. The proposed factor describes the seismic strength requirements in order to restrict maximum storey ductility to a predefined value. Interrelation studies between maximum storey ductility and the Park-Ang damage index are also provided for the damage-based interpretation of the performance levels under consideration. Realistic design examples serve to demonstrate the ability of the proposed factor to convert conventional force-based design to a direct performance-based seismic design procedure.     

基于负责任旅游的政府管理行为

研究旅游,不仅要分析它的发展,还要考虑其所产生的影响。在个人、企业和国家层面都可能存在负责任或不负责任的行为所导致的正面或负面影响。负责任旅游的核心是要采取一种能使旅游的正面影响最大化、负面影响最小化的旅游发展方式,它主张旅游行为主体通过自律性的负责任行为约束途径,而不是期望他人的道德行为实现旅游可持续发展的目标。本文探讨了政府在负责任旅游管理中的行为,包括制定负责任旅游伦理规范、政策以及负责任旅游认证制度建设等,并对认证制度建设中如何构建负责任旅游认证的指标体系提出相应的构想。     

Contact Dynamics of Masonry Block Structures Using Mathematical Programming

A simple variational formulation for contact dynamics is adopted to investigate the dynamic behavior of planar masonry block structures subjected to seismic events. The numerical model is a two-dimensional assemblage of rigid blocks interacting at potential contact points located at the vertices of the interfaces. A no-tension and associative frictional behavior with infinite compressive strength is considered for joints. The dynamic contact problem is formulated as a quadratic programming problem (QP) and an iterative procedure is implemented for time integration. Applications to analytical and numerical case studies are presented for validation. Comparisons with the experimental results of a masonry wall under free rocking motion and of a small scale panel with opening subjected to in-plane loads are also carried out to evaluate the accuracy and the computational efficiency of the formulation adopted.     

景观生态系统及其要素的理论分析

景观生态学是个新兴且发展迅速的学科领域。对其基本概念、原理和理论的研究探索与规范是目前该学科的重要方向。本文即是在前人工作基础上并结合论文作者的理解,比较系统地讨论了景观生态系统及其要素、要素结构等问题。以期对正在形成的学科"范式"提供一定参考。     

从"圣·迭戈"号沉船考古看海上的社会生活

对古代航海船只上社会群体生活状况的研究是社会史研究的重要课题,也是人类航海史研究不可或缺的内涵构成。但由于资料的缺乏,海上社会生活研究一直没有得到足够的关注。近些年来,由于考古工作者对沉船的科学发掘及对生活遗迹与遗物的详细纪录,使得古代海上社会生活的研究获得越来越丰富的资料。本文以"圣·迭哥"号沉船考古发现为基础,并结合文献资料、航海日记以及其他古代沉船的相关信息,对古代海上社会群体的生活状况以及社会关系进行了复原与探讨,以期能为海上社会生活史的深入研究做基础性的工作。     

Influence of Masonry Strength and Openings on Infilled R/C Frames Under Cycling Loading

The influence of masonry infills with openings on the seismic performance of reinforced concrete (R/C) frames that were designed in accordance with modern codes provisions is investigated. Two types of masonry infills were considered that had different compressive strength but almost identical shear strength. Infills were designed so that the lateral cracking load of the solid infill is less than the available column shear resistance. Seven 1/3 – scale, single–story, single–bay frame specimens were tested under cyclic horizontal loading up to a drift level of 40%. The parameters investigated are the opening shape and the infill compressive strength. The assessment of the behavior of the frames is presented in terms of failure modes, strength, stiffness, ductility, energy dissipation capacity, and degradation from cycling. The experimental results indicate that infills with openings can significantly improve the performance of RC frames. Further, as expected, specimens with strong infills exhibited better performance than those with weak infills. For the prediction of the lateral resistance of the studied single-bay, single-story infilled frames with openings, a special plastic analysis method has been employed.     

Effect of Nonlinearity of Frame Buildings on Peak Horizontal Floor Acceleration

Using representative numerical models of eight code-designed steel moment-resisting frame buildings and several ground motions, time-history analyses are performed and a critical evaluation of Peak Horizontal Floor Acceleration (PHFA) demands is conducted. The frames are modeled alternatively as linear and nonlinear systems to isolate the effect of building nonlinearity on PHFA. In most cases, PHFA is reduced when nonlinear behavior of a building is considered; however, in some cases, significant amplification of PHFA is observed. Results from the numerical study provide insight into the trend of modal response modification factors presented taking ground motion spectral shape into account.