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1.
A data-based procedure is presented to develop spectra-compatible time-history records that are based on the dominant probabilistic features of an ensemble of records corresponding to the non-stationary stochastic phenomena of interest (e.g., earthquakes, wind loads, etc). The method requires a statistically significant collection of time-history records that are used to construct the associated covariance kernel of the random process. Subsequently, orthogonal decomposition approaches are used to determine the dominant eigenvectors of the covariance matrix, and these vectors are then linearly combined, with an adjustable amplitude-scale and phase-shift, to determine, via a nonlinear optimization scheme (employing a combination of stochastic and deterministic approaches), a time-history record that matches the target spectrum within a specified error bound. The utility of this approach is demonstrated with several collections of earthquake records from different regions of the world (Japan, Los Angeles, and San Francisco) that are then used to match various spectra widely used in seismic design applications. Issues that impact the selection of the bases vectors to construct the optimum spectra-matching record are discussed, and guidelines are provided for successful implementation of the proposed methodology.  相似文献   

2.
Pollen analyses from a variety of contexts in a Bronze Age cemetery are used to reconstruct aspects of activity around the site during mound construction and use. Various tests are used to assess the reliability of the pollen assemblages recovered, and error analysis used to determine whether perceived differences between contexts are significant and therefore able to support an archaeological interpretation. The data suggest that the mounds were constructed on pasture land, that pyre fuel was predominantly turf, from both heathland and grassland sources, and that polleniferous material including sources ofPlantago lanceolata and cereal pollen were deposited on some cist floors before they were filled.  相似文献   

3.
Geographic compactness standards have been offered as neutral and effective standards constraining redistricting. In this paper, we test this allegation. Redistricting is treated as a combinatoric optimization problem that is constrained by compactness rules. Computer models are used to analyze the results of applying compactness standards when political groups are geographically concentrated. Several population models are used to generate populations of voters, and arbitrary plans are created with combinatoric optimization algorithms. We find that compactness standards can be used to limit gerrymandering, but only if such standards require severe compactness. Compactness standards are not politically neutral—a geographically concentrated minority party will be affected by compactness standards much differently than a party supported by a geographically diffuse population. The particular effects of compactness standards depend on the institutional mechanism that creates districts.  相似文献   

4.
Summary. A ship's Master has to ensure that goods are loaded in such a combination, and stowed in such a manner, that his ship has a safe freeboard and adequate stability. In antiquity these considerations would have been evaluated from experience and by inherited rules of thumb, whereas today stowage factors are used. Greek decorated pottery, with a relatively high stowage factor, is most unlikely to have been used as ballast in the ancient Mediterranean, but small consignments may have been used as 'space-fillers'.  相似文献   

5.
为全面了解秦始皇帝陵园出土青铜水禽表面彩绘装饰工艺的技术内涵,利用显微观察、偏光显微鉴定、拉曼光谱分析等手段,对秦始皇帝陵园K0007陪葬坑出土彩绘青铜水禽表面彩绘装饰工艺进行了系统的考察和研究。研究结果显示,白色颜料为骨白,黑色颜料为炭黑;彩绘层为多层绘制而成,在结构上与秦陵出土陶俑、陶马表面彩绘具有明显区别;彩绘绘制技法包括平涂及堆绘两种,其中堆绘主要用于羽毛纹路羽轴的绘制,施彩工具可能为毛笔或毛刷。彩绘作为青铜器的装饰工艺主要出现于秦汉时期,但并没有得到广泛应用,可能与彩绘装饰自身的脆弱性以及青铜器的功能由礼容器转变为实用器有关。  相似文献   

6.
This paper uses data for intercity air-passenger travel to derive a set of general propulsion and attraction factors for twenty-five large U.S. cities. The paper develops a new way of examining the linkages between flows and nodal attraction. The technique is to assume that the flow data fit a simple gravity model, and then linear programming is used to maximize the consistency of the endogenous propulsion and attraction with the flow data. Various linear models are used to determine the pattern of urban attraction factors that are consistent with the gravitational flows. Linear programming as well as goal programming models are used to develop a set of analyses linking flows to urban hierarchies. Suggestions for further extensions of the method to address substantive issues of urban systems analysis are also provided.  相似文献   

7.
Issue definitions, the way policy issues are understood, are an important component for understanding the policymaking process. Research on issue definitions has been divided between a macro level that examines collective issue definitions and a micro level focusing on the ways in which policy actors frame policy issues. This article develops a model of issue definitions that assumes issues are multidimensional, competition exists among policy actors in defining issues, and that collective issue definitions can be understood as the aggregation of individual issue definitions. This model is then estimated using quantitative text analysis. While various approaches to text analysis and categorization have been used by scholars, latent Dirichlet allocation (LDA), a specific type of topic modeling, is used to estimate issue definitions. Using LDA, witness testimony taken from Congressional hearings that occurred from 1975 to 2012 about the issue of used nuclear fuel (UNF) is examined and seven distinct dimensions of the UNF debate are estimated. The construct validity of these dimensions is checked by testing them against two major policy changes that occurred in the UNF domain. I conclude with a discussion of the strengths and weakness of topic modeling, and how this approach could be used to test hypotheses drawn from several of the major policymaking theories.  相似文献   

8.
This paper describes an analysis to validate the effective hydration temperature (EHT) algorithm for obsidian [Rogers, A.K., 2007. Effective hydration temperature of obsidian: a diffusion-theory analysis of time-dependent hydration rates. J. Arch. Sci. 34, 656-665], using hourly temperature data from the Amargosa Desert Research Site near Beatty, NV. These data were used as input to a numerical model of the temperature-dependent diffusion process, and EHT was calculated yearly and for the aggregate. The same temperature data were processed to extract input parameters for the climatic model reported and used as input for EHT computation. EHT as computed from recorded hourly data was found to be within 1 °C of that computed from the climatic model. It is also shown that computed EHT differences between sites are not sensitive to whether air or surface temperature data are used, as long as they are used consistently; however, surface temperature data must be used if depth corrections are to be made.  相似文献   

9.
王湛 《收藏家》2009,(1):48-52
1958年,江西南城长塘街明益庄王朱厚烨墓的发掘将许多珍稀文物呈现在世人眼前,其中最令人叹为观止的莫过于那些用纯金打造的头饰,璀璨耀眼,熠熠生辉,表现出大明王朝富足的物质生活和能工巧匠的高超技艺,充满时代气息。墓主朱厚烨,为明宪宗朱见深第四子、益端王朱祜槟的嫡长子。明代将皇子皇孙分封各地作藩王,  相似文献   

10.
Land-Use Allocation in the Absence of Complete Market Values   总被引:2,自引:0,他引:2  
This paper describes a method of land-allocation that can be used byplanners and other land managers in the face of market failure. The method integrates theland-allocation approach used in geographic information systems with that used in a generalizedassignment problem. Suitability scores, instead of market prices, are used in assigning competingland uses to individual parcels (pixels) of land. The method is illustrated using a hypotheticalexample involving three competing land uses within a region.  相似文献   

11.
Environmental decision support systems (EDSS) are designed to assist natural resource managers and stakeholders to assess problems and select options for change. EDSS that combine community engagement in developing future scenarios with computer‐based land use planning and modelling tools are widely used internationally. However, these EDSS are often not used after the research and development phase. To best understand why the EDSS are not being used in the long term, the end users of the EDSS should be consulted—a perspective that is lacking in the literature. The research reported here presents the perspectives of stakeholders involved in a community climate change adaptation project in western Canada. Evidence from the community suggests that this project was successful in instigating change. However, the EDSS was not used after the project's end. Our findings indicate that, from the end users’ perspective, the project could have had much greater and sustained success had there been ongoing engagement and communication with them, particularly in the form of continued support for the use of EDSS after the development project.  相似文献   

12.
This paper is an exercise in theory building that explores container form, function, and distribution. Using ethnographic data, environmental reconstructions, and archaeological information, containers are examined within the framework of the container complex, the group of containers used within a system. The results reveal a robust patterning between stone boiling and direct fire boiling and environmental thresholds. It also shows that container fabric used in these cooking strategies patterns by environmental variables. The results are models of the distribution of cooking strategies and the container fabrics used for cooking that can then be applied to the archaeological record.  相似文献   

13.
In this study, M5′ model tree is used to develop a model for prediction of peak time-domain strong ground motion parameters. The main advantages of model trees are that can be easily developed and their formulas are simple and understandable. Selected data from Pacific Earthquake Engineering Research Center (PEER) are used to train the proposed model. Earthquake magnitude, earthquake source to site distance, average shear-wave velocity, and faulting mechanisms are used as input parameters. The developed M5′ based formulas are compared with those of well-known empirical and soft computing based models. The accuracy of the model is evaluated by statistical error parameters.  相似文献   

14.
为了对比分析不同金属线的形貌、材质和工艺差异,理解不同时代金属线差异产生的原因,利用显微形貌观察与科学仪器分析对三组明清纺织品捻金线样品的金属箔条、有机质背层、芯线进行了形貌观察分析。对比了三组捻金线的形貌、结构、尺寸和材质特征,对其制作工艺进行了对比分析,得出了三组捻金线的质量优劣等次,发现了金属线的选用与被装饰织物的时代、功用性质和文化属性之间存在一定关系的现象。含金量高的金属箔条、蚕丝芯线、尺寸纤细、制作精细的捻金线属于高等次的捻金线,常用于等级高、文化属性及功用重要的纺织品文物装饰,其中不带背层的金属线等级又高于带有背层的金属线。本研究对开展金属线系统分析和金属线对比研究具有较高的参考价值。  相似文献   

15.
This article examines whether Tim Ingold's concept of the ‘weather-world’ can be applied within discussions of climate in archaeology. Using a case study of eighteenth century Cumbria, the article first looks at the issues arising when environmental models are used to investigate landscape change. It then assesses the insights on landscape, weather and farming that can be gained from two historical diaries. It is recognised that advances in complex ecosystem and agent-based modelling have improved ‘climate change archaeology’, but that there are aspects of people's relationships with the weather and climate that are ill-suited to quantification. The article concludes by arguing that people's qualitative engagements with the weather are integral to how past people viewed and used the landscape.  相似文献   

16.
Philosophers and historians have long been suspicious of modal and counterfactual claims. I argue, however, that historians often legitimately use modal and counterfactual claims for a variety of purposes. They help identify causes, and hence help explain events in history. They are used to defend judgments about people, and to highlight the importance of particular events. I defend these uses of modal claims against two arguments often used to criticize modal reasoning, using the philosophy of science to ground the truth of modal claims. This analysis puts several important points into perspective, including how certain we can be about our claims about what might have been, and the role that determinism plays in those claims. The proper analysis of modality shows, I argue, that counterfactual claims are legitimate and important, if often uncertain, and that issues of determinism are irrelevant to the modal claims used in historical analysis.  相似文献   

17.
中国明代木质古建西安鼓楼彩绘的分析研究   总被引:1,自引:0,他引:1  
鉴于有关中国木质古建彩绘材料及技术的研究报道较少,本工作通过光学显微镜、扫描电镜能谱(SEMEDX)、X射线衍射及气相色谱质谱(GC/MS)分析方法,对建于公元1380年的中国西安明代鼓楼木建表面彩绘样品进行了科学检测研究,分析了其中的无机材料组成及彩绘所用粘合剂,并收集了所涉及到的相关历史资料。分析结果表明,木建表面彩绘的材料组成和制作技术与历史调查获得的信息完全吻合。地仗层主要由粘土、石灰、干性油(桐油)及纤维织物组成,且地仗层保持最初的原材料。颜料分析结果显示,尽管修复时所使用的粘合剂与最初建造时的粘合剂完全相同,但目前彩绘的颜料即有原来使用的材料,也有十八世纪修复时所使用的材料。  相似文献   

18.
In this paper I present the results of a micro-residue study conducted on ten pièces esquillées (scaled pieces) from Sibudu Cave, South Africa. These artefacts are associated with the Howiesons Poort Industry (∼61.7 and ∼64.7 ka years ago at Sibudu), representing part of the later phase of the Middle Stone Age. Until now, it was unclear on what these pieces were used, and whether they were functional. Previous experimental use-wear work tentatively pointed towards bone processing. However, replication work on stone tool production technology suggests that pièces esquillées are merely the by/end-product of bipolar knapping. I used residue analysis on the Sibudu artefacts because this alternative method has the potential to identify if they were used, and if so, illuminate the specific materials the pieces were used on. Although the sample is small, all the pièces esquillées reveal a clear animal processing signal. There are some bone deposits on the utilised edges that may substantiate bone processing, or perhaps a bone hammer was used with them, but additional study, including Later Stone Age artefacts, is needed to assess the feasibility of these observations. It remains possible that the artefacts are core reduced pieces that were subsequently used as tools or simply knapped with a bone hammer.  相似文献   

19.
朱菁  董欣  贺建雄  潘湖江 《人文地理》2015,30(3):118-124,49
为解决早晚高峰交通拥堵问题,有必要研究居民通勤特征,为城市规划、管理提供参考。本文以西安为实证研究对象,采用空间分层随机抽样法发放问卷进行调查研究,并将研究结果与东部类似城市北京进行对比。研究发现西安居民通勤以公共交通为主,但地面交通中私家车高于公交车;通勤时间反映职住分离程度低于东部;以内部通勤和内向通勤为主,同时,运用引力模型对通勤流与城市空间结构的关系进行计算,发现通勤流反映城市空间结构为单中心,在分析通勤特征背后原因的基础上,从城市规划的角度提出相应的治堵建议。  相似文献   

20.
As a rule, data to be used in locational analysis are either rounded up or rounded down. Therefore, error is incurred if such location data are used. The objective of this paper is to examine location error and cost error due to rounding in unweighted minisum and minimax problems in one-dimensional continuous space. Several conclusions on rounding effects are obtained by examining the respective mean-squared errors. First, rounding tends to exert more serious influence on the minisum problem than on the minimax problem. Second, in both location problems, the location error shows a pattern that is the inverse of that of the cost error.  相似文献   

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