Hybrid harmony search algorithm for global optimization

Abstract—This paper proposes two hybrid optimization methods based on Harmony Search algorithm (HS) and two different nature-inspired metaheuristic algorithms. In the first contribution, the combination was between the Improved Harmony Search (IHS) and the Particle Swarm Optimization (PSO). The second contribution merged the IHS with the Differential Evolution (DE) operators. The basic idea of hybridization was to ameliorate all the harmony memory vectors by adapting the PSO velocity or the DE operators in order to increase the convergence speed. The new algorithms (IHSPSO and IHSDE) have been compared to the IHS, DE, PSO and some other algorithms like DHS and HSDM. The DHS and HSDM are two existing algorithms, which use different hybridization concepts between HS and DE. All of these algorithms have been evaluated by different test Benchmark functions. The results demonstrated that the hybrid algorithm IHSDE have the better convergence speed into the global optimum than the IHSPSO and the standard IHS, DE and PSO

Learning automata and sigma imperialist competitive algorithm for optimization of single and multi-objective functions

Evolutionary Algorithms (EA) consist of several heuristics which are able to solve optimisation tasks by imitating some aspects of natural evolution. Two widely-used EAs, namely Harmony Search (HS) and Imperialist Competitive Algorithm (ICA), are considered for improving single objective EA and Multi Objective EA (MOEA), respectively. HS is popular because of its speed and ICA has the ability for escaping local optima, which is an important criterion for a MOEA. In contrast, both algorithms have suffered some shortages. The HS algorithm could be trapped in local optima if its parameters are not tuned properly. This shortage causes low convergence rate and high computational time. In ICA, there is big obstacle that impedes ICA from becoming MOEA. ICA cannot be matched with crowded distance method which produces qualitative value for MOEAs, while ICA needs quantitative value to determine power of each solution. This research proposes a learnable EA, named learning automata harmony search (LAHS). The EA employs a learning automata (LA) based approach to ensure that HS parameters are learnable. This research also proposes a new MOEA based on ICA and Sigma method, named Sigma Imperialist Competitive Algorithm (SICA). Sigma method provides a mechanism to measure the solutions power based on their quantity value. The proposed LAHS and SICA algorithms are tested on wellknown single objective and multi objective benchmark, respectively. Both LAHS and MOICA show improvements in convergence rate and computational time in comparison to the well-known single EAs and MOEAs

The development of a swarm intelligent simulation tool for sugarcane transport logistics systems.

Thesis (M.Sc.)-University of KwaZulu-Natal, 2008.Transport logistics systems typically evolve as networks over time, which may result in system rigidity and cause changes to become expensive and time consuming. In this study a logistics model, named TranSwarm, was developed to simulate sugarcane harvesting, transport and mill-yard activities for a mill supply area. The aim was to simulate produce flow, and allow individual working entities to make decisions, driven by rules and protocols, based on their micro-environments. Noodsberg mill was selected as a case study because of low current levels of synchronization. Growers were assumed to operate independent harvesting and transport systems causing inconsistent convergences at the mill. This diverse and fragmented system provided a suitable environment to construct a model that would consider interactions between individual growers and their respective transport systems. Ideally, by assessing the micro-decisions of individuals and how they influence the larger holistic supply chain, TranSwarm quantifies the impacts of different types of transport practices, such as staggering shift changes, transport scheduling, core sampling and consortium-based logistics. TranSwarm is visual, mechanistic and represents key entities, such as roads, farm groupings and the mill. The system uses discrete events to create a dynamic and stochastic environment from which observations and conclusions can be drawn. This approach potentially allows stakeholders to identify key components and interactions that may jeopardize overall efficiency and to use the system to test new working protocols and logistics rules for improving the supply chain

Using Ideation Tools for Face-to-face Collaboration Within Complex Design Problems

The focus of this research are ideation tools and their ability to catalyse ideas to address complex design problems. Complex design problems change over time and the interactions among the components of the problem and the interaction between the problem and its environment are of such that the system as a whole cannot be fully understood simply by analyzing its components (Cilliers 1998, pp. I). Ideation for this research is defined as a process of generating, developing and communicating ideas that are critical to the design process (Broadbent, in Fowles 1979, pp. 15). Based on Karni and Arciszewski, who stated that ideation tools should act more like an observer or suggester rather than controller or an expert, I defne design ideation tools as tools or methods that enhance, increase and improve the user's ability to generate ideas with the client (Karni and Arciszewski 1997; Reineg and Briggs 2007). Based on a survey of over 70 ideation tools, protocol analysis of design activities, a web survey and semistructured interviews, I conclude that designers and clients may not have sufficient knowledge of ideation or ideation tools in either testing or practice as a catalyst for generating possibilities and that measuring ideation tools based on how many ideas they generate is misleading because it relates creativity and idea generation but does not adequately reflect the participants' experience. This research suggests that participants' cultural perceptions of design ideation and the design process actively inhibit idea generation and that a shift from design outcome led ideation tool design to designing ideation tools that engage design contexts are necessary to effectively address complex design problems. This research identifed a gap in ideation tools for designers to collaborate with their clients during the ideation phase to catalyse possibilities to complex design problems as the contribution to new knowledge

Using ideation tools for face-to-face collaboration within complex design problems

The focus of this research are ideation tools and their ability to catalyse ideas to address complex design problems. Complex design problems change over time and the interactions among the components of the problem and the interaction between the problem and its environment are of such that the system as a whole cannot be fully understood simply by analyzing its components (Cilliers 1998, pp. I). Ideation for this research is defined as a process of generating, developing and communicating ideas that are critical to the design process (Broadbent, in Fowles 1979, pp. 15). Based on Karni and Arciszewski, who stated that ideation tools should act more like an observer or suggester rather than controller or an expert, I defne design ideation tools as tools or methods that enhance, increase and improve the user's ability to generate ideas with the client (Karni and Arciszewski 1997; Reineg and Briggs 2007). Based on a survey of over 70 ideation tools, protocol analysis of design activities, a web survey and semistructured interviews, I conclude that designers and clients may not have sufficient knowledge of ideation or ideation tools in either testing or practice as a catalyst for generating possibilities and that measuring ideation tools based on how many ideas they generate is misleading because it relates creativity and idea generation but does not adequately reflect the participants' experience. This research suggests that participants' cultural perceptions of design ideation and the design process actively inhibit idea generation and that a shift from design outcome led ideation tool design to designing ideation tools that engage design contexts are necessary to effectively address complex design problems. This research identifed a gap in ideation tools for designers to collaborate with their clients during the ideation phase to catalyse possibilities to complex design problems as the contribution to new knowledge.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Abstract Chaotic dynamic characteristics in swarm intelligence

Swarm intelligence (SI) is an innovative distributed intelligent paradigm whereby the collective behaviors of unsophisticated individuals interacting locally with their environment cause coherent functional global patterns to emerge. The intelligence emerges from a chaotic balance between individuality and sociality. The chaotic balances are a characteristic feature of the complex system. This paper investigates the chaotic dynamic characteristics in swarm intelligence. The swarm intelligent model namely the particle swarm (PS) is represented as an iterated function system (IFS). The dynamic trajectory of the particle is sensitive on the parameter values of IFS. The Lyapunov exponent and the correlation dimension are calculated and analyzed numerically for the dynamic system. Our research results illustrate that the performance of the swarm intelligent model depends on the sign of the maximum Lyapunov exponent. The particle swarm with a high maximum Lyapunov exponent usually achieves better performance, especially for multi-modal functions. # 2006 Elsevier B.V. All rights reserved