Modeling the Seismic Response of Modern URM Buildings Retrofitted by Adding RC Walls

Modern unreinforced masonry buildings with reinforced concrete slabs are often retrofitted by inserting reinforced concrete walls. The main advantages of this technique are the increase in strength and displacement capacity with respect to masonry structures. This article presents two modeling approaches for evaluating such structures: a shell-element model and a macro-element one. The objective is to formulate practical recommendations for setting up a macro-element model using as input the geometry of the structure and results from standard material tests. Structural configurations of masonry buildings, in which the insertion of reinforced concrete walls is an efficient retrofit technique, are also investigated.     

Geographically Weighted Regression: A Method for Exploring Spatial Nonstationarity

Spatial nonstationarity is a condition in which a simple “global” model cannot explain the relationships between some sets of variables. The nature of the model must alter over space to reflect the structure within the data. In this paper, a technique is developed, termed geographically weighted regression, which attempts to capture this variation by calibrating a multiple regression model which allows different relationships to exist at different points in space. This technique is loosely based on kernel regression. The method itself is introduced and related issues such as the choice of a spatial weighting function are discussed. Following this, a series of related statistical tests are considered which can be described generally as tests for spatial nonstationarity. Using Monte Carlo methods, techniques are proposed for investigating the null hypothesis that the data may be described by a global model rather than a non-stationary one and also for testing whether individual regression coefficients are stable over geographic space. These techniques are demonstrated on a data set from the 1991 U.K. census relating car ownership rates to social class and male unemployment. The paper concludes by discussing ways in which the technique can be extended.     

Frequency Estimation of Natural Hazards and Extremes

Detailed studies of natural hazards such as floods, droughts, tropical cyclones and earthquakes often require estimates of the frequencies of occurrence of particular extreme events However, the techniques for making these estimates are sometimes misunderstood and misapplied, particularly with regard to the forms of frequency distribution that are assumed or implied The most appropriate distribution and estimation technique depend on several factors, including the physical nature of the event, the available data and the intended application of the estimate. The present paper attempts to review these matters, giving attention to a range of techniques from simple graphical extrapolation to reasonably rigorous analytical procedures. It is pointed out that, no matter how sophisticated the technique, there is always some inaccuracy and uncertainty in such estimates. Attention is therefore also given to relatively simple methods of assessing the degree of uncertainty.     

Sizing Up State Policy Innovation Research

In the literature on state policy innovation, there are three major explanations for what causes a government to adopt a new policy. One is the internal determinants model, which posits that the main factors leading a state to innovate are internal political, social and economic characteristics of the stale. The other two are diffusion models—the regional diffusion model, and the national interaction model—which see slate policy adoptions as emulations of earlier adoptions by other states. Each of the three models has been associated with a distinct strategy for empirical testing. The regional diffusion model has been tested with factor analysis, the national interaction model with time-series regression, and the internal determinants model with cross-sectional regression. In this paper, I explore the ability of these "single-explanation" methodologies to detect the true innovation process underlying stale policy adoptions, by applying these methodologies to data generated from simulated innovation processes with known characteristics. I find that the methodologies often yield incorrect conclusions about the character of innovation. I conclude by presenting an agenda for refining a superior alternative methodology: the event history analysis approach to state policy innovation research introduced by Berry and Berry (1990).     

The Forgotten Semantics of Regression Modeling in Geography

This article is concerned with the semantics associated with the statistical analysis of spatial data. It takes the simplest case of the prediction of variable y as a function of covariate(s) x, in which predicted y is always an approximation of y and only ever a function of x, thus, inheriting many of the spatial characteristics of x, and illustrates several core issues using “synthetic” remote sensing and “real” soils case studies. The outputs of regression models and, therefore, the meaning of predicted y, are shown to vary due to (1) choices about data: the specification of x (which covariates to include), the support of x (measurement scales and granularity), the measurement of x and the error of x, and (2) choices about the model including its functional form and the method of model identification. Some of these issues are more widely recognized than others. Thus, the study provides definition to the multiple ways in which regression prediction and inference are affected by data and model choices. The article invites researchers to pause and consider the semantic meaning of predicted y, which is often nothing more than a scaled version of covariate(s) x, and argues that it is naïve to ignore this.     

An inversion procedure for obtaining collision frequency profiles from swept-frequency absorption measurements

A method is presented which inverts swept-frequency Al absorption data to obtain collision frequency profiles in the E- and F-regions of the ionosphere. The method gives consistent results from successive sets of measurements and the profiles obtained are consistent with other measurements of collision frequency. Accounting for D-region absorption is a difficulty affecting the accuracy of the collision frequencies obtained at the lowest heights, but model simulations show that values at higher heights are not affected seriously. The technique can be used to obtain results for the F1-region for which there are very few previous measurements.Comparison with theoretical calculations of collision frequency show agreement in the form of the altitude variation. That is, there is a rapid decrease with altitude through the E-region which becomes much less in the F-region so that the collision frequency becomes almost constant with height. This change is caused by electron-ion collisions becoming more dominant than electron—neutral collisions. However, consistent with other observers, we find a major discrepancy between the magnitude of the experimental and theoretical values. If the electron and ion temperatures are assumed equal, the experimental values are approximately five times greater. The discrepancy increases if Te >Ti in the theoretical calculations.     

Mine blast vibration response spectrum for structural vulnerability assessment: case study of heritage masonry buildings

Ground-borne vibrations induced by mine blasting are typically of low amplitudes, which are not considered a major concern for modern engineered structures. However, historic structures are often considered more vulnerable due to inadequate knowledge regarding the state of construction materials and structural response. Specifically, the construction materials used might be fragile or have deteriorated to a stage that could be vulnerable to such vibrations. Simplistic rule based on peak ground motion parameter has been adopted worldwide for safety assessment, while the frequency characteristics of vibrations are not taken into account. Further, there is very limited study on response of heritage structures to near-field blasting. This article presents a practical structural vulnerability assessment method for mine blast-induced vibrations. In particular, a design response spectrum model is proposed based on close range measurements of nearby mine blasting, which is compared with an existing design spectrum model for far-field mine blasts and a typical design spectrum model for earthquake actions. The method is illustrated through a case study of heritage masonry buildings in Australia. The unique blast data presented and the generalized methodology would be useful to both structural engineers and blast engineers in considering potential effects of blasting on heritage structures.     

DYNAMIC RESPONSE OF SKEW HIGHWAY BRIDGES

A simplified bridge model suitable for use in a parametric study of short-span skew highway bridges and bridges with stiffness eccentricity is presented. The proposed model is simple, yet it captures all essential features that affect the dynamic response of these bridges. Using this simplified model, formulas for computing earthquake response of the bridges are developed and parameters that significantly influence the dynamic response of the bridges are identified. The study indicates that the response of a given skew bridge depends not only on its deck aspect ratio, the stiffness eccentricity ratio, the skew angles, its natural frequencies, but also on the frequency ratio. In particular, the rotational to translational frequency ratio has a pronounced influence on the dynamic response of the bridge. It is found that skew bridges with high rotational to translational frequency ratios often exhibit less dependence on such parameters as deck aspect ratios, stiffness eccentricity ratios and skew angles.     

Rugged Plateaus and Extensive Floodplains — Modelling Landform Evolution in a Northern Australian Catchment

Medium to large natural catchments are often more spatially heterogeneous than small catchments or single landforms. Attempting to model landform evolution of large areas is consequently more complex. This paper demonstrates that modelling landform evolution in medium to large catchments can be improved by calibrating the model to smaller, more geomorphologically homogenous sub‐catchments. The paper investigates landform evolution in the Ngarradj catchment in the Northern Territory of Australia (a medium scale catchment of approximately 67 km²). The catchment is complex and contains two distinct landform regions; an upland plateau region with highly dissected sandstone and shallow, sandy soils, and a lowlands region with gentle, wooded slopes and floodplains with deep, sandy soils. The SIBERIA landform evolution model is calibrated and applied to the Ngarradj catchment. The complexity of the Ngarradj catchment is incorporated into the modelling by dividing the catchment into three sub‐catchments (Swift Creek (SC), Upper Main (UM) and East Tributary (ET)) which are relatively homogeneous and for which hydrology and sediment transport data are available. A discharge‐area relationship and long‐term, sediment loss rates for the catchment are derived based on an annual series flood frequency analysis of a 20 year runoff record predicted in a previous study. Sediment transport modelling incorporates both suspended and bedload sediment loss. The denudation rates derived using these data are 37, 63 and 77 mm kyr^?1 for the SC, UM and ET sub‐catchments, respectively. Model predictions indicate that the UM sub‐catchment will have the greatest mean erosion. This is balanced by the large amount of deposition that will occur in the upper Ngarradj valley of the UM sub‐catchment. Further deposition occurs on the floodplain of Ngarradj, with the area between the SC and ET/UM (up‐stream) sub‐catchments experiencing a small net accretion of sediment (15 mm kyr^?1).     

A Wavelet‐Based Extension of Generalized Linear Models to Remove the Effect of Spatial Autocorrelation. 基于小波扩展广义线性模型消除空间自相关的影响

Biogeographical studies are often based on a statistical analysis of data sampled in a spatial context. However, in many cases standard analyses such as regression models violate the assumption of independently and identically distributed errors. In this article, we show that the theory of wavelets provides a method to remove autocorrelation in generalized linear models (GLMs). Autocorrelation can be described by smooth wavelet coefficients at small scales. Therefore, data can be decomposed into uncorrelated and correlated parts. Using an appropriate linear transformation, we are able to extend GLMs to autocorrelated data. We illustrate our new method, called the wavelet‐revised model (WRM), by applying it to multiple regression with response variables conforming to various distributions. Results are presented for simulated data and real biogeographical data (species counts of the plant genus Utricularia [bladderworts] in grid cells throughout Germany). The results of our WRM are compared with those of GLMs and models based on generalized estimating equations. We recommend WRMs, especially as a method that allows for spatial nonstationarity. The technique developed for lattice data is applicable without any prior knowledge of the real autocorrelation structure.     

县域城乡关联度评价指标体系构建与应用——以大西安为例

在总结城乡一体评价指标体系研究进展的基础上,从城乡一体化过程中城市和乡村这两个子系统出发,选取城市发展水平、乡村发展水平和城乡协调水平三个功能目标层构建县域城乡关联度评价指标体系。以大西安地区各区县为例进行应用研究发现,不同地区的城乡关联度、城市发展水平、乡村发展水平和城乡协调水平相互之间存在一致性和差异性,其中城市发展水平对城乡关联度影响最大。     

DETECTING MULTIVARIATE OUTLIERS IN ARTEFACT COMPOSITIONAL DATA*

Multivariate statistical analysis of artefact compositional data, usually undertaken to investigate structure in the data, often incidentally reveals the presence of multivariate outliers. Much statistical methodology dealing with the detection of such outliers is not well suited to archaeometric data that, in the event, consist of two or more groups. The paper provides examples to illustrate the importance of detecting and dealing with outliers, and critically examines a range of different approaches to outlier detection. The examples show that cluster analysis, the technique most widely used for this purpose, can fail to reveal outliers clearly identified by other methods.     

Typologies of Advantage and Disadvantage: Socio‐economic Outcomes in Australian Metropolitan Cities

Australia's metropolitan cities have undergone significant social, economic and demographic change over the past several decades. In terms of socio‐economic advantage and disadvantage these changes, which are often associated with globalisation, wider economic and technological restructuring, the changing demographics of the population and shifts in public policy are not evenly dispersed across cities, but represent a range of often contrasting outcomes. The current paper develops a typology of socio‐economic advantage and disadvantage for locations across Australian metropolitan cities. More specifically, the paper takes a range of Australian Bureau of Statistics data and uses a model‐based approach with clustering of data represented by a parameterised Gaussian mixture model and discriminant analysis utilised to consider the differences between the clusters. These clusters form the basis of a typology representing the range of socio‐economic and demographic outcomes at the local community level.     

TUNING OF SEISMIC HAZARD ESTIMATES BY MEANS OF OBSERVED SITE INTENSITIES

Probabilistic seismic hazard is usually assessed by means of computer codes using seis-mogenic sources, parametric catalogues, seismicity rates and attenuation relationships. All these ingredients are conditioned by expert judgement that influences the final results. Even the attenuation relationships, though strictly based on experimental data, are considered a weak point due to the difficulty of modelling the interaction between seismic energy radiation and site response, and because earthquakes do not usually repeat themselves according to one theoretical model. Recently, methods making wide use of site intensity data have been developed in regions such as Italy, where the observed seismic history at selected sites is quite exhaustive. We analyzed these observations to assess seismic hazard at about 600 sites. We used a probabilistic counting technique, integrating the observations (when necessary), with computed shakings obtained from a logistic-type attenuation model. The results were then compared with the estimates provided by the recent seismic hazard map of Italy, compiled according to the traditional probabilistic seismic hazard approach. The match shows significant differences for some sites. A tentative explanation which seems to point to three alternatives is provided: (1) The mismatch between the two methodologies might appear because the stationary assumption has a poor fit with reality (at least in certain areas); (2) Some sites show a response that is systematically different from the average values predicted using attenuation relationships; (3) The definition of seismogenic zones leads to a bias in the seismicity rate estimate.     

A method for the identification of the location of regional cultural boundaries

Although it is widely accepted that exchangeable items often have a role in boundary maintenance, the forms of regression analysis used by archaeologists in the analysis of artifact distributions are generally unable to recognize the marked boundary effects that might be theoretically predicted, and alternative techniques are clearly required. In this study, it is suggested that single boundary profiles are well represented by a two-parameter family of functions related to the Verhulst model for population growth. A curve of this type was fitted by an iterative technique to empirical data values provided by the distribution of various regional series of late Iron Age coinage in southern Britain, and preliminary results suggest that in most cases the boundaries identified correspond to those which have been inferred on the basis of historical evidence. In addition, the analysis has drawn attention to a number of features which might repay further study—a close relationship between boundaries and major rivers, and a suggestion of the existence of distinct boundary zones between discrete territorial units. There are, however, a number of problems in the application of the method, and further work is needed.     

Contouring techniques for archaeological distributions

The visual presentation of spatial distributions in archaeology is often in the form of contour diagrams. This paper reviews some of the contouring techniques that are generally available and presents a method that is particularly well suited to archaeological data on a regular grid. A variant of the method is given to deal with irregularly spaced data. Several examples are shown to demonstrate the wide applicability of the chosen contouring technique.     

九寨沟风景区日游客量预测研究

要实现风景区科学规划与永续利用,游客数量的预测是关键,其中短期的游客数量预测则是景区资源统一管理与合理调度的直接依据。本文分析了九寨沟的游客到达历史数据,建立了游客到达的日预测回归模型和BP修正模型,实际数据证明该模型有效。     

What was the Prevalence of Malignant Disease in the Past?

A method is described which can be used to calculate the number of tumours that might be expected to occur in a group of skeletons. The method of calculation is based on published data that relate to the frequency with which various primary tumours metastasize to bone and on the number of deaths from malignant disease at the turn of the century. The method has been applied to one archaeological site and the results indicate that the number of tumours found—although very small—is within the limits suggested by the model.     

Empirical convection models for northward IMF

It is clear that polar cap convection during times of northward IMF is more structured and of lower mean speed than at times of southward IMF. This, coupled with the fact that the polar cap is smaller, means that empirical models are more difficult to construct with certainty. It is also clear that sunward flow deep in the polar cap is often observed, but its connection with the rest of the flow pattern is controversial.At present, empirical models are of three types: ‘statistical’ models wherein data from different days but with similar IMF conditions are averaged together; ‘pattern recognition’ models, which are built up by examining individually hundreds of passes to derive a ‘typical’ pattern which embodies features frequently observed; and ‘assimilative’ models, which use data of different types and from as many locations as possible, but all taken at the same time, in order to derive a snapshot (or series of snapshots) of the entire pattern.Each type of model has its own difficulties. Statistical models, by their very nature, smooth out flow features (e.g. the convection reversal, and the locus of sunward flow deep in the polar cap) which are not found at precisely the same invariant latitudes and magnetic local times on different days. Pattern recognition models are better at reproducing small-scale features, but the large-scale pattern can be a matter of interpretation. Assimilative models (such as AMIE) hold out the best hope for creating instantaneous, global convection patterns; however, the analysis technique tends to be most irregular (and least reliable) in the regions which are not well covered by in situ data. It appears that, at least at times, a four cell model with sunward flow at the highest and lowest latitudes, and antisunward flow in between, is consistent with the observations. At other times, the observations may be consistent with a two-cell convection pattern, but which includes significant meanders within the polar cap.