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1.
结构系统模态参数识别方法研究进展   总被引:5,自引:0,他引:5  
对结构系统模态参数识别方法近十几年来的最新研究成果进行了综述和总结。分析了模态参数识别方法的发展趋势,并对其中的典型研究成果进行简要的介绍。最后指出非线性时变结构系统识别方法的研究具有非常重要的理论意义。  相似文献   

2.
3.
This paper explores the legacy of the great French experimental physicist Victor Regnault through the example of Gabriel Lippmann, whose engagement with electrical standardization during the early 1880s was guided by Regnault's methodological precept to measure ‘directly’. Lippmann's education reveals that the theoretical practice of ‘direct’ measurement entailed eliminating extraneous physical effects through the experimental design, rather than, like physicists in Britain and Germany, making numerical ‘corrections’ to measured values. It also provides, paradoxically, exemplars of the qualitative theoretical practices that sustained Regnault's misguided ambition to avoid theory. By considering the largely negative reactions to Lippmann's proposals for selecting suitable electrical units and methods of measuring the ohm, this paper associates these theoretical practices with the ineffectual rhetorical strategies employed by Lippmann to promote his work, and thereby indicates that the practice of direct measurement was limited to French experimental physics. Whilst this result aligns readily with the existence of divergent nineteenth century British and German cultures of precision, it emerges from a very different disciplinary context in which the practice of precision electrical measurement developed independently of submarine telegraphy. This is because, as this paper illustrates, telegraphic engineering and experimental physics remained separate professions in France.  相似文献   

4.
自从1919年10月世界上最早的工程院——瑞典皇家工程科学院成立以来,已有大约40多个国家和地区相继成立了工程院或类似的组织,它们各具特色,开展了各种各样的活动,推动了工程科学技术的进步、促进了经济的繁荣并造福人类。本文对国外工程院各方面的情况进行了综合的分析。  相似文献   

5.
Outliers, level shifts, and variance changes are commonplace in applied time series analysis. However, their existence is often ignored and their impact is overlooked, for the lack of simple and useful methods to detect and handle those extraordinary events. The problem of detecting outliers, level shifts, and variance changes in a univariate time series is considered. The methods employed are extremely simple yet useful. Only the least squares techniques and residual variance ratios are used. The effectiveness of these simple methods is demonstrated by analysing three real data sets.  相似文献   

6.
Exact measurements are a central practice of modern physics. In certain cases, they are essential for determining values of coefficients, for confirming theories, and for detecting the existence of effects. The history of piezoelectricity at the end of the nineteenth century reveals two different methods of exact measurement: a mathematical versus an “artisanal” approach. In the former, a scientist first carried out the experiment and later employed mathematical methods to reduce error. In the latter, a scientist physically manipulated the experimental apparatus to bypass possible sources of error before its performance. These two approaches were related to German theoreticians and to French experimentalists, respectively. However, affiliation with a particular school rather than nationality was the decisive factor in the differences between the two approaches. Despite differences, adherents of both approaches sought to attain high precision and to eliminate even small experimental errors.This history exhibits the complexity and flexibility of experiments and their analysis. It supports the claim of the “New Experimentalism” that theory does not supply complete directions for practical experimental decisions. An example for this is found in the way an experimental error was discovered (after incorrect results had already been published) only by a comparison to an earlier experiment rather than to a theory.  相似文献   

7.
This article approaches eighteenth-century views on scientific academies by examining Haller's utterances, public and private, especially those occasioned by the founding of the Göttingen Society. It deals in turn with his understanding of the distinctive purpose of academies, with his explanation of the chief ways in which they realized this end, with his thoughts on their broader usefulness, and finally with his various reasons for considering close ties with the state to be essential to their productive and harmonious operations.  相似文献   

8.
The aim of this paper is twofold. Firstly, I give a brief account of the history of the debate on the problem of defining disposition concepts from its beginning in the late 1920s until today. This account is divided into four parts, corresponding with 2, 3, 4 and 5 of the paper, each of which deals with a major period of the debate. Section 2 reports up to the mid-1950s. Section 3 deals with important contributions to the discussion between 1955 and 1958. However, the progress made around that time was far ahead of the logical theory and techniques which were needed for foundational reasons and for a better understanding of the basic notions. Some logical techniques appropriate for that aim were developed in the late 1960s and early 1970s. Though not uncontroversial, those logical techniques resulted in improvements of the insights gained in the mid-1950s; I shall report on those logical techniques and their application to the problem of defining disposition concepts in Section 4. In the early 1990s, however, the whole tradition of defining disposition concepts in terms of conditionals has been challenged by some strong counter-examples which are treated in Section 5. Finally, the second of the aims of this paper is explored in Section 6, in which I sketch very briefly the current stage of the debate by discussing and evaluating the most recent approaches to the subject.  相似文献   

9.
In this paper, three theories of progress and the aim of science are discussed: (i) the theory of progress as increasing explanatory power, advocated by Popper in The logic of scientific discovery (1935/1959); (ii) the theory of progress as approximation to the truth, introduced by Popper in Conjectures and refutations (1963); (iii) the theory of progress as a steady increase of competing alternatives, which Feyerabend put forward in the essay “Reply to criticism. Comments on Smart, Sellars and Putnam” (1965) and defended as late as the last edition of Against method (1993). It is argued that, contrary to what Feyerabend scholars have predominantly assumed, Feyerabend's changing attitude towards falsificationism—which he often advocated at the beginning of his career, and vociferously attacked in the 1970s and 1980s—must be explained by taking into account not only Feyerabend's very peculiar view of the aim of science, but also Popper's changing account of progress.  相似文献   

10.
Mining education was one of the areas of technical savoir transformed during the eighteenth century. Mining academies arose and spread through Europe in the second half of that century. This happened first in the German states and the Austrian dominions, due to the cameralistic system, and soon developed elsewhere through a transfer of the German model to France (Ecole des mines) as well as to other francophone and Spanish-speaking areas (Belgium and Piedmont-Savoy, Spain and America). The mining academies may rightly be considered among the prototypes of technical high schools (Polytechniques and Technische Hochschulen) established during the nineteenth century. In the course of exploring some of the details of this development, the present paper aims at suggesting outlines to be followed in pursuing a comparative analysis of special schools for the training of technicians and mining officers (Bergschulen and Bergakademien). A second aim is to examine more closely the Italian case as a typical example of adaptation, although on a smaller scale, of French and German experiences. This can provide a framework within which to place further microanalyses and case-studies.  相似文献   

11.
This article examines how Hans G. Gadamer’s philosophical hermeneutics can contribute to contemporary debates on the concept of ‘presentism’. In the field of the history of science, this term is usually employed in two ways. First, ‘presentism’ refers to the kind of historiography which judges the past to legitimate the present. Second, this concept designates the inevitable influence of the present in the interpretation of the past. In this paper, I argue that both dimensions of the relationship between the present and the past are explored by Hans G. Gadamer in Truth and Method and other texts. In the first place, Gadamer’s critique of historicism calls into question the anti-presentist ideal of studying the past for ‘its own sake’. In the second place, Gadamer’s thesis that all understanding inevitably involves some prejudice poses the question of the inherent “present-centredness” of historical interpretations. By examining Gadamer’s hermeneutics, I seek to provide historians with new arguments and perspectives on the question of ‘presentism’.  相似文献   

12.
时频分布中交叉项抑制的研究进展   总被引:5,自引:0,他引:5  
从整个时频分析发展的历史来看,其发展过程是以克服Wigner-Ville分布(WVD)的缺陷为动力的。本文以抑制Wigner-Ville分布中的交叉项为线索,在简要介绍时频分析中已有的一些方法的基础上,综述了近年来在抑制交叉项干扰方面的研究进展,并对现存的有关问题进行了探讨。  相似文献   

13.
综述了石墨烯的电化学特征以犀近几年来石墨烯在电分析方面的重要研究进展,并对石墨烯的制备方法进行了评述;认为寻求高导电率石墨烯的制备方法、深入探讨石墨烯的电化学催化机理,以及将基于石墨烯的电化学生物传感技术应用于食品、环境、生命科学等领域中电活性分子的实时在线检测将是石墨烯在电分析领域的重要研究方向。  相似文献   

14.
There are many geologic resource assessment techniques available that can be used to estimate the hydrocarbon potential of frontier basins. The techniques do not, however, produce discovery rate forecasts, which are critical to government and industry planners. Various methods of predicting the discovery rate in frontier basins are reviewed and appraised within the context of the drilling history of Canada's Scotian Shelf. The reviewed models include a mean historical discovery rate technique, the exponential decline model, a logistic curve technique and a class of models based on a sampling without replacement approach to prediction. Models are found to perform best over the longer forecast horizons, with those models based on the sampling without replacement technique tending to perform best.  相似文献   

15.
在现有基于Agilent 4395A阻抗分析仪的无线传感器测量系统的基础上,设计了一个便携的LRC参数测试仪,给出了测量无线电感传感器及检测线圈LRC值的测量原理及其提取LC值的算法.最后通过仿真验证了该算法的正确性.  相似文献   

16.
I present an account of classical genetics to challenge theory-biased approaches in the philosophy of science. Philosophers typically assume that scientific knowledge is ultimately structured by explanatory reasoning and that research programs in well-established sciences are organized around efforts to fill out a central theory and extend its explanatory range. In the case of classical genetics, philosophers assume that the knowledge was structured by T. H. Morgan’s theory of transmission and that research throughout the later 1920s, 30s, and 40s was organized around efforts to further validate, develop, and extend this theory. I show that classical genetics was structured by an integration of explanatory reasoning (associated with the transmission theory) and investigative strategies (such as the ‘genetic approach’). The investigative strategies, which have been overlooked in historical and philosophical accounts, were as important as the so-called laws of Mendelian genetics. By the later 1920s, geneticists of the Morgan school were no longer organizing research around the goal of explaining inheritance patterns; rather, they were using genetics to investigate a range of biological phenomena that extended well beyond the explanatory domain of transmission theories. Theory-biased approaches in history and philosophy of science fail to reveal the overall structure of scientific knowledge and obscure the way it functions.  相似文献   

17.
Summary Simple light microscopic methods for routine observation and checking cortical granules of vital mammalian eggs will be described. By using interference contrast and dark field techniques, even small cortical granules can easily be examined. These methods are time-saving compared to the usual ones using an electron microscope. They make distribution studies possible without difficulties.  相似文献   

18.
压电陶瓷变压器是一种新型固态电子器件,具有高转换效率、高能量密度、结构简单、体积小、无电磁噪声的特点,在电子产品微型化的过程中起到了十分重要的作用。本文回顾了压电陶瓷变压器的发展历史,阐述了压电陶瓷变压器的基本工作原理,介绍了压电陶瓷变压器所用的新型压电材料、振动模式和几何结构、外围电路三大方面的最新研究进展。通过对比国内外在压电变压器领域的研究和应用现状,指出了我国发展压电变压器的优势和前景,并提出了压电变压器产业的发展方向。  相似文献   

19.
多媒体取证     
多媒体取证是信息安全领域的重要研究内容之一,主要应用于司法取证、刑侦取证,是电子证据鉴别等领域中的关键技术之一.目前篡改媒体内容大量涌现,严重危及个人隐私与社会稳定,多媒体取证已成为一项迫切需求的技术.本文概要介绍了多媒体取证技术的特点和原理,并且从媒体源辨识、内容篡改检测、处理历史分析、反取证四方面阐述多媒体取证的发展现状和趋势,分析了各种取证技术所面临的难点.最后展现了未来技术发展的若干问题与可能趋势.  相似文献   

20.
Fibonacci’s treatment of so-called recreational problems in his Liber Abbaci has been interpreted as an early episode both in the history of systems of linear equations, and in the history of negative numbers. However, these problems are also interesting in their own right. We discuss some of the conventions which seem to have governed these problems. By considering certain pairs of problems, where one problem is unsolvable and its partner is solvable, we show that Fibonacci went to a significant effort to conform to these conventions. We also examine the methods which he could have used to construct his problems.  相似文献   

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