Optimizing hydropower reservoir operation using hybrid genetic algorithm and chaos

Author name used in this publication: Chun-tian CheungAuthor name used in this publication: K. W. Chau2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

The Self-Organization of Interaction Networks for Nature-Inspired Optimization

Over the last decade, significant progress has been made in understanding complex biological systems, however there have been few attempts at incorporating this knowledge into nature inspired optimization algorithms. In this paper, we present a first attempt at incorporating some of the basic structural properties of complex biological systems which are believed to be necessary preconditions for system qualities such as robustness. In particular, we focus on two important conditions missing in Evolutionary Algorithm populations; a self-organized definition of locality and interaction epistasis. We demonstrate that these two features, when combined, provide algorithm behaviors not observed in the canonical Evolutionary Algorithm or in Evolutionary Algorithms with structured populations such as the Cellular Genetic Algorithm. The most noticeable change in algorithm behavior is an unprecedented capacity for sustainable coexistence of genetically distinct individuals within a single population. This capacity for sustained genetic diversity is not imposed on the population but instead emerges as a natural consequence of the dynamics of the system

The Self-Organization of Interaction Networks for Nature-Inspired Optimization

Over the last decade, significant progress has been made in understanding complex biological systems, however there have been few attempts at incorporating this knowledge into nature inspired optimization algorithms. In this paper, we present a first attempt at incorporating some of the basic structural properties of complex biological systems which are believed to be necessary preconditions for system qualities such as robustness. In particular, we focus on two important conditions missing in Evolutionary Algorithm populations; a self-organized definition of locality and interaction epistasis. We demonstrate that these two features, when combined, provide algorithm behaviors not observed in the canonical Evolutionary Algorithm or in Evolutionary Algorithms with structured populations such as the Cellular Genetic Algorithm. The most noticeable change in algorithm behavior is an unprecedented capacity for sustainable coexistence of genetically distinct individuals within a single population. This capacity for sustained genetic diversity is not imposed on the population but instead emerges as a natural consequence of the dynamics of the system

Novel cost allocation framework for natural gas processes: methodology and application to plan economic optimization

Natural gas plants can have multiple owners for raw natural gas streams and processing facilities as well as for multiple products. Therefore, a proper cost allocation method is necessary for taxation of the profits from natural gas and crude oil as well as for cost sharing among gas producers. However, cost allocation methods most often used in accounting, such as the sales value method and the physical units method, may produce unacceptable or even illogical results when applied to natural gas processes. Wright and Hall (1998) proposed a new approach called the design benefit method (DBM), based upon engineering principles, and Wright et al. (2001) illustrated the potential of the DBM for reliable cost allocation for natural gas processes by applying it to a natural gas process. In the present research, a rigorous modeling technique for the DBM has been developed based upon a Taylor series approximation. Also, we have investigated a cost allocation framework that determines the virtual flows, models the equipment, and evaluates cost allocation for applying the design benefit method to other scenarios, particularly those found in the petroleum and gas industries. By implementing these individual procedures on a computer, the proposed framework easily can be developed as a software package, and its application can be extended to large-scale processes. To implement the proposed cost allocation framework, we have investigated an optimization methodology specifically geared toward economic optimization problems encountered in natural gas plants. Optimization framework can provide co-producers who share raw natural gas streams and processing plants not only with optimal operating conditions but also with valuable information that can help evaluate their contracts. This information can be a reasonable source for deciding new contracts for co-producers. For the optimization framework, we have developed a genetic-quadratic search algorithm (GQSA) consisting of a general genetic algorithm and a quadratic search that is a suitable technique for solving optimization problems including process flowsheet optimization. The GQSA inherits the advantages of both genetic algorithms and quadratic search techniques, and it can find the global optimum with high probability for discontinuous as well as non-convex optimization problems much faster than general genetic algorithms

Güncel en iyileme algoritmalarının paralel ve birlikte uygulamaları ve performans analizleri

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.En iyileme yöntemleri yapılan işin en iyi yapılmasını sağlamak için kullanılırlar. Bu tekniklerin kullanılmasındaki temel hedef her zaman için en iyi çözümleri yakalayabilmektir. Uygunluk veya hata değeri tanımlanabilen her sistemin en iyi çözümünün elde edilmesinde en iyileme algoritmaları kullanılabilir. Sadece ait oldukları problemlere özgü olmaları ve yüksek hesaplama maliyeti içermeleri gibi sebepler nedeniyle mevcut geleneksel en iyileme algoritmalarının kullanımı çok sayıda parametre içeren gerçek dünya problemlerinin çözümünde bazen yeterli olmayabilir. Bu gibi durumlarda daha az işlem ile daha kısa sürede en iyi çözüme yakınsayabilen meta-sezgisel yöntemlerin kullanımı daha makul çözümler olarak karşımıza çıkmaktadır. Son 20 yıl içerisinde doğadan ilham alınarak çok sayıda meta-sezgisel en iyileme algoritması geliştirilmiştir. Buna paralel olarak bazı araştırmacılar mevcut algoritmalar üzerinde birtakım iyileştirmeler yapmışlar, bazıları da birden fazla algoritmayı bir arada kullanarak performansı daha yüksek melez yöntemler elde etmişler ve daha sonra bu yöntemleri kullanarak gerçek dünya problemlerine en iyi çözümler üretmişlerdir. Bu tez çalışmasında sistem kimliklendirme süreci, yapay sinir ağı eğitimi, sempozyum katılımcı listelerinin düzenlenmesi, slab kesme uzunluklarının planlanması gibi gerçek dünyaya ait problemlere birer en iyileme problemi olarak yaklaşılmış, seçilen güncel ve yaygın meta-sezgisel algoritmalar kullanılarak geleneksel yöntemlerin çözümleri ile rekabet edebilen çözümler üretilmiştir. Ayrıca, karar ağacı tasarım süreci hem kombinatoryal hem de nümerik en iyilemeleri içeren bir problem olarak ele alınmış, olası karar ağacı tasarımları arasında sistematik arama yapan yeni bir yöntem ile karar ağacı tasarımı gerçekleştirilmiştir. Önerilen yöntemle elde edilen test sonuçlarının aynı veri setinin kullanıldığı daha önceki karar ağacı çalışmaları ile elde edilen sonuçlardan daha iyi olduğu görülmüştür. Son olarak, yapay arı koloni ve göçmen kuşlar en iyileme algoritmaları kullanılarak yeni modifiye, melez ve paralel çalışma sistematikleri önerilmiştir. Önerilen yöntemlerin performans testlerinden elde edilen sonuçlar, onların daha iyi keşif ve yakınsama yeteneklerine sahip olduklarını ortaya koymuştur.Optimization methods are employed in order to make a job in an optimal way. The main aim of their usage is to get an optimal solution in every execution. Optimization algorithms can be applied to find optimal solutions for the systems whose fitness or error calculations can be defined. Sometimes, existing conventional optimization algorithms may be insufficient for the real world problems having many parameters because of the reason that they are problem specific and have higher calculation costs. Since metaheuristic algorithms can find near optimal solutions with less calculations requiring lower time, their usages seem more feasible for these cases. Within the past 20 years, so many metaheuristic algorithms which are inspired by the nature have been developed by researchers. In parallel to these studies, while some of the researchers were working on some enhancements for existing algorithms, some of them were working on their hybrid forms. Then, they tried to find more optimal solutions for real world problems by using these new enhanced and hybrid algorithms. In this dissertation study, some real world problems such as system identification process, artificial neural network training, preparation of symposium attendee lists, scheduling slab cutting lengths etc. are thought to be optimization problems. Some competitive solutions with respect to solutions of the conventional methods are generated to these real world problems by using some recent and common metaheuristic algorithms. In addition, thinking the decision tree construction process as a problem including both numerical and combinatorial optimizations, a novel decision tree construction method which makes a systematic search among possible decision tree designs is proposed to get optimal decision tree. It is seen that the results obtained by proposed method are better than those of previous studies using same data set. Finally, some modified, hybrid and parallel running strategies using artificial bee colony and migrating birds optimization algorithms are proposed. It is observed from the performance test results that proposed strategies have better exploration and exploitation capabilities