Bayesian Parameter Identification and Model Selection for Normalized Modulus Reduction Curves of Soils

This work develops a procedure that involves the use of Bayesian approach to quantify data scatterness, estimates the optimal values of model parameters, and selects the most appropriate model for the construction of normalized modulus reduction curves of soils. The proposed procedure is then demonstrated using real observation data based on a set of comprehensive resonant column tests on coarse-grained soils conducted in the study.     

Reduction Factors for Seismic Design Spectra for Structures with Viscous Energy Dampers

A simple mathematical expression is proposed to estimate spectra reduction damping factors for seismic design of systems with viscous dampers. The expression is obtained from the ratios between ordinates of uniform hazard spectra associated with two different return intervals (50 and 125 years), corresponding to sites with different types of soil within the Valley of Mexico. The expression proposed depends on the dominant period of the soil, and on both the vibration period and damping ratio of the structural system. Values of the damping factors proposed here are comparable to those recommended by different authors and seismic design building codes.     

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。     

The Analysis of Stone Tool Procurement, Production, and Maintenance

Researchers who analyze stone tools and their production debris have made significant progress in understanding the relationship between stone tools and human organizational strategies. Stone tools are understood to be morphologically dynamic throughout their use-lives; the ever-changing morphology of stone tools is intimately associated with the needs of tool users. It also has become apparent to researchers that interpretations of lithic analysis are more productive when the unique contexts and situations for which lithic artifacts were made, used, modified, and ultimately discarded are considered. This article reviews the recent literature on stone tool production with an emphasis on raw material procurement, manufacturing techniques, and tool maintenance processes as they relate to adaptive strategies of toolmakers and users.     

Estimating original flake mass from 3D scans of platform area

This study confirms the increased capacity to predict flake mass that arises from more accurately measuring surface area in three dimensions using a digital scanner. We also reveal the existence of significantly different relationships between platform area and flake mass for flakes with different platform types and ventral and dorsal morphologies. These different relationships between platform surface area and mass have not been previously identified, and reveal the complexity of platform/mass relationships. Using multivariate regression of 3D platform surface area and external platform angle we improve the accuracy of predictions of original flake mass. We propose a method for studying reduction intensity on retouched flakes, based on comparing predictions of the initial mass of the flake with measurements of the mass following retouching to estimate the amount of mass removed through retouching. We name this approach the Initial-/Terminal-Mass Comparison, or ITMC. Our experiments demonstrate that the capacity of the 3D platform scans to predict flake mass, and by implication the capacity of the ITMC to estimate mass loss, rivals or exceeds the capacity demonstrated for existing reduction measures.     

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.     

Measuring core reduction using 3D flake scar density: a test case of changing core reduction at Klasies River Mouth,South Africa

A new core reduction index is presented, calculated as the ratio of flake scar number to 3D surface area (SDI). The index is tested experimentally on five types of core (blade, discoid, Levallois, biface and multiplatform cores) and then applied to the core assemblages from five sub-stages of the Middle Stone Age at Klasies River Mouth, South Africa. Preliminary results indicate that the SDI possesses the desirable attributes of a successful reduction index and is a significant improvement on traditional proxy measures of core reduction. The results of the archaeological case study confirm previous untested observations that cores from the Howiesons Poort and MSAIII sub-stages are more heavily reduced than preceding and following stages, and that local and exotic raw materials as well as different types of cores are all more heavily reduced during these periods. The SDI fills a significant lacuna in available core reduction measures.     

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.     

Floodplain management in Canada: overview and prospects

Flooding is an important natural process. It plays a vital role in the maintenance of floodplain and shoreline ecosystems. Yet, it also is a hazard, in that floods put human life and property at risk. Paradoxically, flooding is a hazard only because humans have chosen to occupy flood‐vulnerable areas, such as riverine floodplains and lake or coastal shorelines. Recent major floods in Canada are a reminder that vulnerability to floods remains high. Responses to the flooding “problem” have evolved in Canada from an emphasis on controlling “water out of place” through structural measures such as dams and dikes, to managing human behaviour using zoning to keep development away from hazardous areas. In Canada, the federal‐provincial Flood Damage Reduction Program, initiated in 1975, has been an important vehicle for delivering a consistent, national approach to floodplain management. However, as of early 1999, the federal government has allowed the program to wind down while it reconsiders its role in water management ‐ effectively leaving the field of flood damage reduction to the provinces. This creates both challenges and opportunities. The challenge will be to avoid a return to the spiral of increasing flood damages and disaster assistance payments that characterized the period up to 1975. At the same time, however, opportunities exist to take stock of floodplain management, and to evaluate alternative future directions, including a more integrated approach to flooding. Les inondations font partie d'un processus naturel important. En particulier, elles contribuent largement à entretenir les écosystèmes des plaines inondables et des zones riveraines. Pourtant, elles constituent aussi un risque dans la mesure où elles mettent en danger la vie des gens et les propriétés. Paradoxalement, les inondations ne sont un risque que parce que les être humains ont choisi d'occuper des zones susceptibles d‘être inondées, comme les plaines riveraines inondables, les rives des lacs et le littoral marin. Les inondations importantes qui se sont récemment produites au Canada nous ont rappelé notre grande vulnérabilitéà leur égard. Notre réaction à l'endroit du “problème” que représentent les inondations a d'ailleurs évolué. Au lieu de nous concentrer comme autrefois sur l'adoption de mesures structurelles comme des barrages et des digues pour empêcher l'eau de s’échapper librement, nous agissons maintenant sur le comportement humain en décourageant les installations dans les zones dangereuses. Au Canada, le programme fédéral‐provincial de réduction des dommages causés par les inondations, lancé en 1975, a beaucoup contribuéà l‘élaboration d'une approche nationale cohérente dans la gestion des plaines inondables. Cependant, au début de 1999, le gouvernement fédéral, qui repense son rôle dans la gestion des eaux, a autorisé l’élimination progressive du programme, laissant tout bonnement aux provinces la responsabilité de la réduction des dommages causés par les inondations. Ce nouvel état de choses soulève évidemment toutes sortes de difficultés, mais aussi des possibilités. Entre autres difficultés, il faudra éviter de retomber dans la spirale des paiements d'aide aux sinistrés et de compensation pour les dommages issus des inondations qui a caractérisé la période antérieure à 1975. Parallèlement, sur le plan des possibilités, il faudra prendre en main la gestion des plaines inondables et évaluer les différentes orientations possibles, y compris l'adoption d'une approche plus intégrée de lutte contre les inondations.     

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。