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文章根据极大熵基本原理并运用排列组合理论推导出OD矩阵反推的极大熵模型;然后用拉格朗日乘子法求得该模型的非线性方程组,并运用Newton算法对此非线性方程组求解,得到动态OD估计矩阵。最后,在实例应用中,应用此模型和文章给出的模型解法取得了令人满意的结果。 相似文献
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由路段交通量估计交通起止点矩阵OD时,一般都要求解非线性的目标函数,使用通常的随机搜索算法容易陷入局部最优的陷阱。本文将模拟退火算法应用于OD估计问题,使用双层规划的OD估计模型,并给出了启发性算法。 相似文献
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利用道路交通流量进行OD矩阵反推的模型与方法综述 总被引:1,自引:0,他引:1
分别从静态和动态角度对基于路段交通流量的OD矩阵反推模型与方法进行了综述,并依据不同的分类标准对文献中出现的OD矩阵反推模型与方法进行了分类. 相似文献
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研究目标:利用高频数据准确估计和预测高维积分波动率矩阵,并将矩阵的预测值应用于资产投资组合的构造中。研究方法:通过保留p×p维已实现波动率矩阵的特征向量,对积分波动率矩阵的特征值进行预测,本文将积分波动率矩阵的估计和预测问题转化为p个一维积分波动率的估计和预测问题。研究发现:对高维已实现波动率矩阵过于发散的特征值进行调整能够提高矩阵估计的准确性;对资产收益率的积分波动率矩阵建立动态模型可以提高矩阵预测的精度。研究创新:将高维矩阵的估计和预测问题转化为矩阵特征向量的估计以及一维特征值的估计和预测问题;基于高频数据并建立资产收益率积分波动率矩阵的动态模型提高了资产投资组合的样本外表现。研究价值:本文提出的积分波动率矩阵估计和预测方法能够保证矩阵估计值和预测值的正定性;本文的预测方法能够提高矩阵的预测精度,能够在复杂的金融市场中构造低风险的资产组合。 相似文献
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从系统理论和运输需求的概念出发,分析了国内外铁路路网运输能力的研究成果。从OD流矩阵的角度提出了铁路路网系统运输能力的概念,在此基础上构建了铁路路网系统运输能力的双层规划计算模型,该模型已最大化OD流矩阵乘数从为上层规划模型的目标,以最小化广义运输费用为下层模型目标,并提供了基于Lingo软件和Double-sweep算法的实用解法。最后,以一个铁路路网为例,用模型进行了求解,得出了路网最大能力及实现此最大能力的车流径路,并指出了进一步研究的方向。 相似文献
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从系统理论和运输需求的概念出发,分析了国内外铁路路网运输能力的研究成果.从OD流矩阵的角度提出了铁路路网系统运输能力的概念,在此基础上构建了铁路路网系统运输能力的双层规划计算模型,该模型已最大化OD流矩阵乘数从为上层规划模型的目标,以最小化广义运输费用为下层模型目标,并提供了基于Lingo软件和Double-sweep算法的实用解法.最后,以一个铁路路网为例,用模型进行了求解,得出了路网最大能力及实现此最大能力的车流径路,并指出了进一步研究的方向. 相似文献
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Tim Power 《Revue internationale de statistique》2003,71(1):59-67
This paper outlines the ICT statistical developments that the ABS has undertaken over recent years. These developments have been on both the supply side (ICT industry) and the demand side (use of IT by sector). The content of ABS ICT surveys has changed significantly over the last few years and are expected to develop further in line with industry changes and emerging policy needs.
Recent developments in household collections have been the inclusion of IT use questions in the 2001 Census of Population and Housing and in various ABS social surveys such as Children's Participation in Culture and Leisure Activities. Annual business IT use surveys are now conducted and include topics such as Internet commerce and IT security. Biennial ICT industry surveys are conducted to provide data on ICT production, imports and exports, ICT industry employment, performance and structure information. An Internet activity survey is run every six months and provides regional Internet access details and infrastructure details on Internet service providers.
A major development for 2002–03 will be the compilation of an ICT satellite account. ABS intends to produce an ICT Information Development Plan to guide its future statistical development work in the ICT field. 相似文献
Recent developments in household collections have been the inclusion of IT use questions in the 2001 Census of Population and Housing and in various ABS social surveys such as Children's Participation in Culture and Leisure Activities. Annual business IT use surveys are now conducted and include topics such as Internet commerce and IT security. Biennial ICT industry surveys are conducted to provide data on ICT production, imports and exports, ICT industry employment, performance and structure information. An Internet activity survey is run every six months and provides regional Internet access details and infrastructure details on Internet service providers.
A major development for 2002–03 will be the compilation of an ICT satellite account. ABS intends to produce an ICT Information Development Plan to guide its future statistical development work in the ICT field. 相似文献
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En este estudio se analiza el incumplimiento del salario mínimo durante el periodo 2003–2012 en diez países de Europa central y oriental con salario mínimo obligatorio nacional. A partir de los datos de EU‐SILC y la metodología propuesta por Bhorat, Kanbur y Mayet (2013), se cuantifica la incidencia y magnitud del incumplimiento. Se realizan análisis de regresión sobre determinantes individuales, laborales y macroeconómicos. Aunque la incidencia permanece relativamente baja, los trabajadores a los que se dirigen las políticas de salario mínimo parecen los más expuestos a su incumplimiento. Con el tiempo, una mayor incidencia se asocia a una razón más alta entre salario mínimo y salario medio. 相似文献
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Value at Risk in the Suburbs: Eminent Domain and the Geographical Politics of the US Foreclosure Crisis
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Christopher Niedt Brett Christophers 《International journal of urban and regional research》2016,40(6):1094-1111
Several US counties and local governments have recently considered a novel solution to the foreclosure crisis. They plan to use eminent domain to compel the owners of mortgage debt—and specifically of private‐label mortgage‐backed securities—to sell the debt to the government at a price reflecting the loan's market value. The government would then restructure the debt and resell it to new investors. The plans are striking because—in contrast to both development‐driven eminent domain and the federal subprime bank bailout—they would force investors to assume asset devaluation and increased long‐term risk. Notably, the plans have emerged as an instance of financialization‐focused politics in suburbs and suburban cities of color, specifically majority‐black and ‐Latino/a suburbs. Local support for the plans, we argue, is rooted in the long‐term disinvestment of these ‘suburbs of exception', which became targets of subprime lending and eventually sites where the ‘financial exception' has been localized. But these demographic shifts, fragmentation and fiscal pressures have at the same time created a suburban political terrain in which the plans have gained their strongest political support. 相似文献
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Christian Busch 《Journal of Management Studies》2024,61(3):1110-1151
Serendipity – the notion of making surprising and valuable discoveries – plays a major role in the success of individuals and organizations alike. Previous research has established the importance of serendipity and identified important individual- and organizational-level antecedents. However, the literature has been dispersed and the boundaries of the concept have been blurry, leading to a lack of conceptual clarity and structure, and thus limiting validity and managerial actionability. Based on a systematic literature review, I synthesize existing management-related research on serendipity and explicate the emergence and composition of serendipity in the organizational context. I first identify three necessary conditions that differentiate serendipity from related concepts such as luck or targeted innovation: agency, surprise, and value. Then, I draw from the literature on sensemaking, event-based theorizing, and quantum-based approaches to management to conceptualize the process of cultivating serendipity in the organizational context as a process of enabling potentiality and materialization, and develop a multi-level theory of (cultivating) serendipity. This conceptualization contributes to our collective understanding of how, why, and when (i.e., under what conditions) organizations can leverage the value in the unexpected, which opens up fruitful avenues for further research. 相似文献
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Carl Grodach 《International journal of urban and regional research》2013,37(5):1747-1765
While a growing body of research analyses the functional mechanisms of the cultural or creative economy, there has been little attention devoted to understanding how local governments translate this work into policy. Moreover, research in this vein focuses predominately on Richard Florida's creative class thesis rather than considering the wider body of work that may influence policy. This article seeks to develop a deeper understanding of how municipalities conceptualize and plan for the cultural economy through the lens of two cities held up as model ‘creative cities’ — Austin, Texas and Toronto, Ontario. The work pays particular attention to how the cities adopt and adapt leading theories, strategies and discourses of the cultural economy. While policy documents indicate that the cities embrace the creative city model, in practice agencies tend to adapt conventional economic development strategies for cultural economy activity and appropriate the language of the creative city for multiple purposes. 相似文献
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Mohammad Mohabbat Khan 《Public Management Review》2013,15(2):267-278
NGOs in Bangladesh have been recognized as effective change agents in the socio-economic arena throughout the world. Their contributions in micro credit, non-formal education and primary health care are widely known. NGOs play a significant role in society. NGO accountability, as a result, has become a critical issue. NGO accountability in Bangladesh has been examined here in relation to patrons, clients and themselves. Of the three relationships only accountability to patrons is in a near satisfactory state. Accountability to clients is handicapped by lack of opportunities of beneficiaries to participate meaningfully in NGO policy making. Accountability to themselves is adversely affected due to the adherence to a strictly hierarchical system and the influence of founding and charismatic NGO leaders. 相似文献
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Despite the establishment of high-tech multinational enterprises (MNEs) in Ireland since the late 1950s, the country did not succeed in closing the technological gap with most of its EU counterparts. The weak National System of Innovation (NSI), and in particular low business and government R&D levels, combined with a lack of research and technology linkages between MNEs and indigenous firms, explain these poor results. However, the Shannon region in the West of the country presents some specific institutional characteristics that could theoretically make the region a strong technological enclave. The various actors in the region - i.e. the administrative, financial, political and research institutions, as well as the business organizations - have indeed infused a new type of economic development. After a brief review of the available concepts and models articulated around these actors and their interrelationships, the paper analyses whether the Shannon region, taken as an illustrative example, mirrors a specific economic and technological localized setting. The study is based on a survey of indigenous and foreign firms. 相似文献
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María del Carmen Triana Pamela Gu Olga Chapa Orlando Richard Adrienne Colella 《人力资源管理》2021,60(1):145-204
This article reviews discrimination and diversity research published in Human Resource Management (HRM) over the past 60 years. While discrimination and diversity are very different constructs, it is often informative to study them together, because when people recognize each other's diversity, this can result in bias, stereotyping, and discrimination. We conducted bibliographic searches for terms related to discrimination and diversity as well as a manual search through every title and abstract published in HRM over the last 60 years to assess article relevance. The search resulted in 135 research articles with 136 unique studies (i.e., samples) which are reviewed in this article. Sex and race are the demographics that have been examined the most in HRM, while religion has been examined the least. Moreover, the number of studies examining lesbian, gay, bisexual, transgender, and queer (LGBTQ) employees in the workplace in HRM has grown quickly within the past 10 years, culminating in a recent meta‐analysis. Our review looks at some of the earliest research published, the most recent research published, and the overall trends we identified in the research over the years for both discrimination and diversity articles. We then make future research suggestions and recommendations to advance the study of discrimination and diversity in the coming years. 相似文献
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Chris Rowley John Benson Malcolm Warner 《International Journal of Human Resource Management》2013,24(4-5):917-933
There has been much discussion regarding the possible decline and weakening of national systems of human resource management (HRM). Yet, culture and institutions are often cited as the major stumbling blocks to this outcome. Such constraints may dissipate in the analysis, particularly if ‘regional clusters’ are considered where geographic and cultural closeness and ‘openness’ to similar economic pressures exist. In such cases, it might be postulated that convergence in HRM will occur. We argue that China, Japan and South Korea represent such a cluster. This article examines these countries, to see if a degree of convergence is taking place and if it is towards an identifiable ‘Asian’ model of HRM. A model of change is presented that distinguishes between levels of occurrence and acceptance. Details of the development and practice of HRM in each country are then set out. The article ends with a discussion and implications section and a brief conclusion. 相似文献
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The Early History of the Cumulants and the Gram-Charlier Series 总被引:2,自引:0,他引:2
Anders Hald 《Revue internationale de statistique》2000,68(2):137-153
The early history of the Gram-Charlier series is discussed from three points of view: (1) a generalization of Laplace's central limit theorem, (2) a least squares approximation to a continuous function by means of Chebyshev-Hermite polynomials, (3) a generalization of Gauss's normal distribution to a system of skew distributions. Thiele defined the cumulants in terms of the moments, first by a recursion formula and later by an expansion of the logarithm of the moment generating function. He devised a differential operator which adjusts any cumulant to a desired value. His little known 1899 paper in Danish on the properties of the cumulants is translated into English in the Appendix. 相似文献