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In this article, a choice of the optimum sampling design to study a finite population is studied. Three sampling schemes are compared, viz., Sunter's procedure of unequal probability sampling, stratified sampling under optimum stratification, and simple random sampling without replacement. The comparison is made against a background of various correlation between stratification and survey variables and various variability in the variables. Under weak correlation and large variability, stratification appeared to be more efficient than Sunter's procedure. Under strong correlation and/or low variability in the variables, the latter procedure was the most efficient. Simple random sampling was usually the least efficient. 相似文献
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Mr Andrzej T.Machniewski Mr Janusz Mysliwiec 《内蒙古工业大学学报》2001,20(2):100-104
本文讨论了建筑设备研究所在计算机辅助工程研究中的一些问题,70年代中期该研究所就开始用计算机设计机器及其部件,后来研究所购买了一些相关软件同时也开发了自己的设计软件并在液压起重机和其它建筑机械的设计计算中得到了应用。70-80年代计算机主要用于压力的分析与测量,机械的振动与稳定性分析,研究所从事机械设计、计算机数据库安全性研究及生态学、工效学方面的研究。在此也感谢其它国家的学者在计算机应用方面的交流与合作。 相似文献
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Marcin K. Dyderski Dorota Wrońska-Pilarek Andrzej M. Jagodziński 《Urban Ecosystems》2017,20(3):639-650
Conservation of biodiversity in urban areas has become crucial to urban green area management. There are several legislative solutions for preservation of species and habitats in cities. One of them is ‘ecological lands’ – a low-restrictive form of protected areas in Poland. We aimed to assess their efficiency in vascular flora biodiversity conservation in the urban environment in Poznań (W Poland; 550,000 inhabitants). We hypothesized that ecological lands which cover <2% of the city area comprise over 50% of taxonomic diversity and over 90% of functional trait-level range of the vascular flora. Analysis of five ecological lands, which covered 1.8% of the whole city area confirmed our hypothesis. In ecological lands studied, we found 564 species of vascular plants, which is 52.9% of the whole city flora. These species belonged to 23 of 29 phytosociological classes represented in the whole city (73.9%). Functional trait distributions in ecological lands studied comprised from 95.8 to 100% of trait distributions in the flora of the whole city. Ecological lands seem to be a good way for conservation of biodiversity in urban areas. The legislative simplicity and low restrictiveness for both land management and recreational utility make ecological lands a much easier form of nature conservation which may be adapted to other cities for more efficient biodiversity management. 相似文献
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Urban Ecosystems - Invasions were studied at different spatial scales, however these scales were rarely compared. The aim of this study is to compare the rate of expansion of eight alien plant... 相似文献
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Andrzej Ruszczynski Robert J. Vanderbei 《Econometrica : journal of the Econometric Society》2003,71(4):1287-1297
We consider the problem of constructing a portfolio of finitely many assets whose returns are described by a discrete joint distribution.We propose mean‐risk models that are solvable by linear programming and generate portfolios whose returns are nondominated in the sense of second‐order stochastic dominance. Next, we develop a specialized parametric method for recovering the entire mean‐risk efficient frontiers of these models and we illustrate its operation on a large data set involving thousands of assets and realizations. 相似文献
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Andrzej S. Kozek 《Australian & New Zealand Journal of Statistics》1998,40(3):317-334
Let X 1 , . . ., Xn be independent identically distributed random variables with a common continuous (cumulative) distribution function (d.f.) F , and F^n the empirical d.f. (e.d.f.) based on X 1 , . . ., Xn . Let G be a smooth d.f. and Gθ = G (·–θ) its translation through θ∈ R . Using a Kolmogorov-Lévy type metric ρα defined on the space of d.f.s. on R , the paper derives both null and non-null limiting distributions of √ n [ ρα ( Fn , Gθn ) – ρα ( F, Gθ )], √ n (θ n –θ) and √ nρα ( Gθ , Gθ ), where θ n and θ are the minimum ρα -distance parameters for Fn and F from G , respectively. These distributions are known explicitly in important particular cases; with some complementary Monte Carlo simulations, they help us clarify our understanding of estimation using minimum distance methods and supremum type metrics. We advocate use of the minimum distance method with supremum type metrics in cases of non-null models. The resulting functionals are Hadamard differentiable and efficient. For small scale parameters the minimum distance functionals are close to medians of the parent distributions. The optimal small scale models result in minimum distance estimators having asymptotic variances very competitive and comparable with best known robust estimators. 相似文献
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Andrzej Rozanski 《Human Resource Development International》2013,16(1):91-99
The health care industry in Taiwan has faced many challenges in recent years. To tackle those challenges, many hospitals in Taiwan began using management techniques used in other industries. As a result, quality management has become important within Taiwan's health care industry. This study provides a perspective on how this health care industry, by developing both quality control circle (QCC) practices and organizational learning techniques, responded to those challenges. In this study, the authors conducted a comprehensive review of studies published between 1995 and 2007 in Taiwan. The review focused on the quality management, QCC, organizational learning and health care organization aspects reported in previous studies. The authors applied the 4Is (intuiting, interpreting, integrating and institutionalizing) conceptual framework of Crossan et al. (1999) (Crossan, M.M., H.W. Lane, and R.E. White. 1999. An organizational learning framework: From intuition to institution. Academy of Management Review 24, no. 3: 522–37). in their discussion of the linkage between quality improvement activities and organizational learning. The results revealed the existence of a link between organizational learning and QCC activities. In addition, the reviewed QCC activities facilitated organizational learning and contributed to health care quality improvements in the studied hospitals. Finally, QCC practices in hospitals facilitated dissemination of organizational learning concepts in those hospitals. 相似文献
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Pawel Korzynski Andrzej Krzysztof Kozminski Anna Baczynska Michael Haenlein 《European Management Journal》2021,39(2):226-235
Contrary to the previous leadership theories, which focus on specific and narrow aspects of leadership such as employee characteristics, leader’s authenticity, or boundary spanning, the bounded leadership theory is a broad and complex concept. It takes simultaneously many constraints, which are related to activities on an individual, team, organization, and stakeholder level. This study applies the bounded leadership theory to analyze the leadership constraints as the mediator of the relationship between leadership competencies and effectiveness. Our findings show that leaders’ competencies are not enough for them to be effective. Specific competencies enable leaders to overcome the set of constraints and then to increase their effectiveness. 相似文献
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The paper reviews the methodology of multi-objective modeling and optimization used in decision support based on computerized analytical models (as opposed to logical models used in expert systems) that represent expert knowledge in a given field. The essential aspects of this methodology relate to its flexibility: modeling and optimization methods are treated not as goals in themselves but as tools that help a sovereign user (an analyst or a decision maker) to interact with the model, to generate and analyze various decision options, to learn about possible outcomes of these decisions. Although the applications of such methods in negotiation and mediation support is scarce yet, their flexibility increases essentially the chances of such applications. Various aspects of negotiation and mediation methods related to multi-objective optimization and game theory are also reviewed. A possible application of the MCBARG system for supporting negotiation related to the acid rain problem is briefly summarized. 相似文献