• Title/Summary/Keyword: global metropolis

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Posterior density estimation for structural parameters using improved differential evolution adaptive Metropolis algorithm

  • Zhou, Jin;Mita, Akira;Mei, Liu
    • Smart Structures and Systems
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    • v.15 no.3
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    • pp.735-749
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    • 2015
  • The major difficulty of using Bayesian probabilistic inference for system identification is to obtain the posterior probability density of parameters conditioned by the measured response. The posterior density of structural parameters indicates how plausible each model is when considering the uncertainty of prediction errors. The Markov chain Monte Carlo (MCMC) method is a widespread medium for posterior inference but its convergence is often slow. The differential evolution adaptive Metropolis-Hasting (DREAM) algorithm boasts a population-based mechanism, which nms multiple different Markov chains simultaneously, and a global optimum exploration ability. This paper proposes an improved differential evolution adaptive Metropolis-Hasting algorithm (IDREAM) strategy to estimate the posterior density of structural parameters. The main benefit of IDREAM is its efficient MCMC simulation through its use of the adaptive Metropolis (AM) method with a mutation strategy for ensuring quick convergence and robust solutions. Its effectiveness was demonstrated in simulations on identifying the structural parameters with limited output data and noise polluted measurements.

Development and Efficiency Evaluation of Metropolis GA for the Structural Optimization (구조 최적화를 위한 Metropolis 유전자 알고리즘을 개발과 호율성 평가)

  • Park Kyun-Bin;Kim Jeong-Tae;Na Won-Bae;Ryu Yeon-Sun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.1 s.71
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    • pp.27-37
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    • 2006
  • A Metropolis genetic algorithm (MGA) is developed and applied for the structural design optimization. In MGA, favorable features of Metropolis criterion of simulated annealing (SA) are incorporated in the reproduction operations of simple genetic algorithm (SGA). This way, the MGA maintains the wide varieties of individuals and preserves the potential genetic information of early generations. Consequently, the proposed MGA alleviates the disadvantages of premature convergence to a local optimum in SGA and time consuming computation for the precise global optimum in SA. Performances and applicability of MGA are compared with those of conventional algorithms such as Holland's SGA, Krishnakumar's micro GA, and Kirkpatrick's SA. Typical numerical examples are used to evaluate the computational performances, the favorable features and applicability of MGA. The effects of population sizes and maximum generations are also evaluated for the performance reliability and robustness of MGA. From the theoretical evaluation and numerical experience, it is concluded that the proposed MGA Is a reliable and efficient tool for structural design optimization.

Product stewardship - Progress or Promises

  • Scott, David
    • Proceedings of the Korea Society of Environmental Toocicology Conference
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    • 2003.10a
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    • pp.131-142
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    • 2003
  • It's about three in the morning in a little farming village near the thriving metropolis of Sao Paulo in Brazil. Miguel, a 14-year-old schoolboy is fast asleep. Miguel was worried when he climbed into bed and drew the covers up. He was concerned about his homework - not that he had not done it. But rather what he had discovered while doing it. His homework was to interview his father, a tomato farmer, about how he uses pesticides and what precautions he takes to use them safely.

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Fast Simulated Annealing with Greedy Selection (Greedy 선택방법을 적용한 빠른 모의 담금질 방법)

  • Lee, Chung-Yeol;Lee, Sun-Young;Lee, Soo-Min;Lee, Jong-Seok;Park, Cheol-Hoon
    • The KIPS Transactions:PartB
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    • v.14B no.7
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    • pp.541-548
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    • 2007
  • Due to the mathematical convergence property, Simulated Annealing (SA) has been one of the most popular optimization algorithms. However, because of its problem of slow convergence in the practical use, many variations of SA like Fast SA (FSA) have been developed for faster convergence. In this paper, we propose and prove that Greedy SA (GSA) also finds the global optimum in probability in the continuous space optimization problems. Because the greedy selection does not allow the cost to become worse, GSA is expected to have faster convergence than the conventional FSA that uses Metropolis selection. In the computer simulation, the proposed method is shown to have as good performance as FSA with Metropolis selection in the viewpoints of the convergence speed and the quality of the found solution. Furthermore, the greedy selection does not concern the cost value itself but uses only dominance of the costs of solutions, which makes GSA invariant to the problem scaling.

MCMC Algorithm for Dirichlet Distribution over Gridded Simplex (그리드 단체 위의 디리슐레 분포에서 마르코프 연쇄 몬테 칼로 표집)

  • Sin, Bong-Kee
    • KIISE Transactions on Computing Practices
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    • v.21 no.1
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    • pp.94-99
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    • 2015
  • With the recent machine learning paradigm of using nonparametric Bayesian statistics and statistical inference based on random sampling, the Dirichlet distribution finds many uses in a variety of graphical models. It is a multivariate generalization of the gamma distribution and is defined on a continuous (K-1)-simplex. This paper presents a sampling method for a Dirichlet distribution for the problem of dividing an integer X into a sequence of K integers which sum to X. The target samples in our problem are all positive integer vectors when multiplied by a given X. They must be sampled from the correspondingly gridded simplex. In this paper we develop a Markov Chain Monte Carlo (MCMC) proposal distribution for the neighborhood grid points on the simplex and then present the complete algorithm based on the Metropolis-Hastings algorithm. The proposed algorithm can be used for the Markov model, HMM, and Semi-Markov model for accurate state-duration modeling. It can also be used for the Gamma-Dirichlet HMM to model q the global-local duration distributions.

Optimisation of Infrastructure within the Melbourne Urban plan

  • Koorosh Gharehbaghi;Vincent Raso
    • International conference on construction engineering and project management
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    • 2011.02a
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    • pp.299-303
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    • 2011
  • Congestion is a growing concern of many global cities and the demands on Infrastructure services within a locale coupled by the rising expectations from the growing population places stress on these cities. This entails the ability to build a sustainable community that requires an understanding and recognition of Population growth, changing demographics and the ever changing urban development on both a macro and micro level. Infrastructure is an integral part of Australian economy, particularly the 'Infrastructure Assets Management' which highlights the importance towards the development of sustainable communities for Melbourne's future. Melbourne 2030 is a comprehensive representation of government's response to a wide-ranging population growth within Melbourne metropolitan and surrounding areas. Urban plan and specific Infrastructure Assets Planning needs not only to provide sufficient Infrastructure to a community, but it must also be efficient and innovative so that it produces an optimised management system. A system that incorporates engineering techniques that will be sustainable for decades to come by maintaining an acceptable level of services to its intended community in an effective manner, which also strengthens service delivery. The fundamental challenges for optimization of Infrastructure with the Melbourne urban plan is, the ability to manage and sustain maintenance of Infrastructure to provide the acceptable level of service required by the community in a most effective manner which also strengthens service delivery to contribute towards Melbourne 2030. This paper particularly investigates some of the fundamental issues within the Melbourne urban plan such as Infrastructure Asset Management, AusLink and the Australian Road Management Act 2004, which the Governments at all levels must deal with to provide an economically viable solution to the changing Infrastructure so it may suits the needs and services the strategies of a metropolis.

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The New Urbanization Process and Changing Urban Space of Daejon in the 1990s (1990년대 대전의 신도시화 과정과 도시 공간의 변화)

  • Choi, Gum-Ae;Kang, Hyun-Soo;Choi, Byung-Doo
    • Journal of the Korean association of regional geographers
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    • v.10 no.1
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    • pp.67-82
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    • 2004
  • There is a general agreement that the global social-economic system is undergoing fundamental changes, which can be explained in terms of the transformation of production system from the Fordism to Post-Fordism since the 1980s. These fundamental changes have resulted in the 'new urbanization' process in the most of large cities in the developed countries. The aim of this paper is to identify the 'new urbanization' process in a large city in Korea that is, Daejon. For the propose, this paper tries to examine and conceptualize empirically the changes of economic, political, social-cultural, and spatial aspects of Daejon metropolis in the respect of 'new urbanization'. The major findings of this essay are summarized as follows. First of all, Daejon economy has experienced new changes, that is the development of service economy and high tech industry. But the old industry still remain important in the urban economy. Secondly, in the political aspect, new civil movements flourish in the city, while the political power of Jaminlyeon, a pro-conservative and narrow-regionalism party, once dominated this region, has decreased its influence. Thirdly. the original CBD of Daejon has been declined while new (sub-)CBBs have emerging in Daejon spatial structures. In conclusion, we can find some clues of the new urbanization process in Daejon, but this process is still quite slow and somewhat different from those of large cities of the developed countries.

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District 9 : Science Fiction as Social Critique (<디스트릭트 9> 사회비평으로서의 공상과학)

  • Cho, Peggy C.
    • Cross-Cultural Studies
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    • v.42
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    • pp.505-524
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    • 2016
  • This study examines the ways District 9, a film released in 2009, reworks the sci-fi genre to explore the human encounter with "other" alien populations. Like Avatar, released in the same year, District 9 addresses the tropes of conflict over land and human-alien hybridity and introduces non-humans and aliens, not as invaders, but as objects of human oppression and cruelty. Unlike many other science fiction films where the encounter between humans and non-humans occurs in an unidentifiable future time and location, District 9 crosses genre barriers to engage with urban realism, producing a social critique of contemporary urban population problems. The arrival of aliens in District 9 occurs as part of the recorded human past and the film's action is carried out in the present time in the specifically identified city of Johannesburg. A distinctly anti-Hollywood film that locates the action at the street level, District 9 plays out human anxieties about contact with others by referencing the divisions and conflicts historically attached to South Africa's sprawling metropolis and its current problems of urban poverty and illegal immigrants. Focusing on how this particular urban setting frames the film, the study investigates the ways Blomkamp's sci-fi film about extra-terrestrials presents a curious postcolonial mix of aliens and immigrants surviving in abject conditions in an urban slum and forces a realistic examination of the contemporary social problems faced by South Africa's largest city and by extension other major global cities. The paper also examines the film's representation of the human-alien hybrid and its potential as a force to resist human exploitation of the other. It also claims that though the setting is highly local, District 9 speaks to a wider global audience by making obvious the exploitative practices of profit-seeking multinationals. A sci-fi film that is keen on making a social commentary on urban population conflicts, District 9 resonates with the wider sense of insecurity and fear of others that form the horizon of the uncertain and potentially violent contemporary human world.

Analysis of Consumption Status of Cooked Rice with Different Grains and Related Factors in a Korean Population: Based on Data from 2011 Korean National Health and Nutritional Examination Survey (KNHANES) (한국인의 잡곡밥 섭취 실태 및 관련 요인 분석 - 2011년 국민건강영양조사 자료를 이용하여 -)

  • Han, Gyusang;Lee, Youngmi
    • Journal of the East Asian Society of Dietary Life
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    • v.24 no.6
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    • pp.748-758
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    • 2014
  • This study aimed to investigate consumption status of cooked rice with different grains as well as examine related factors of Koreans. Based on the Korea National Health and Nutrition Examination Survey of the second year (2011) in the fifth stage, we extracted data on 7,190 people aged 1 year and higher who consumed cooked rice with one or more grains and legumes for at least one meal per day. A total of 15,250 meals were analyzed. Approximately 67.6% of subjects consumed cooked rice with different grains for more than one meal. Age was the strongest influencing factor for consuming cooked rice with different grains. Compared with people in their 40s, those aged 19~29 and in their 30s showed lower probabilities (0.5 and 0.6, respectively) of intake of cooked rice with different grains, whereas those in their 50s and 60s showed relatively higher probabilities (1.9 and 5.0, respectively). The intake ratio of cooked rice with different grains was higher in subjects who were females (64.5%), aged 1~18, over 50s, and residing in a metropolis (62.0%). Breakfast (69.6%) showed a higher intake ratio of cooked rice with different grains compared to lunch (49.1%) and dinner (57.9%). Intake of cooked rice with different grains was highest at home (71.2%), whereas it was lowest in restaurants (11.2%). The findings of the current study may be useful in planning dietary guidelines for intake of cooked rice with different grains.