6 research outputs found
A multi-objective evolutionary algorithm based on coordinate transformation
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.In this paper, a novel multiobjective evolutionary algorithm (MOEA/CT) is proposed to better manage convergence and distribution of solutions when MOEAs are used for solving multiobjective optimization problems. The coordinate transformation strategy, an external archive update strategy, and a diversity maintenance strategy are proposed in MOEA/CT. The coordinate transformation strategy in the objective space is designed to find more efficient solutions that can accelerate the convergence process. Based on the coordinate transformation strategy, a novel update strategy and diversity maintenance approach for selecting nondominated solutions from the external archive set are integrated in MOEA/CT for getting better distribution of the solutions. The proposed MOEA/CT is compared with eight state-of-art algorithms on six biobjective and seven tri-objective test problems. In terms of four performance metrics, the comparative experimental results demonstrate that MOEA/CT outperforms the other eight competitors and it can achieve solutions with better distribution and better convergence to the Pareto front. In addition, parameter sensitivity analysis is provided to investigate the effect of a key parameter in MOEA/CT; the proposed three strategies are also studied individually to investigate their contribution to MOEA/CT; the performance analysis along with the capacity of external archive is given to clearly make the influence in MOEA/CT; finally, the scalability performance of MOEA/CT is investigated and compared with five notable many-objective evolutionary algorithms on the DTLZ and WFG test suites with 5, 8, 10, and 15 objectives
Automated Improvement of Software Architecture Models for Performance and Other Quality Attributes
Quality attributes, such as performance or reliability, are crucial for the success of a software system and largely influenced by the software architecture. Their quantitative prediction supports systematic, goal-oriented software design and forms a base of an engineering approach to software design. This thesis proposes a method and tool to automatically improve component-based software architecture (CBA) models based on such quantitative quality prediction techniques
The Borana plateau of southern Ethiopia: Synthesis of pastoral research, development and change, 1980-91
This document is divided in eight chapters. The first chapter reviews rangelands and rangeland development in Ethiopia. The second chapter is an introduction to the Borana Plateau with ref. to natural resources and pastoral society. It reviews secondary information on geology and sociology, as well as original information on climate, soils, wildlife, plant ecology and water resources for the central Borana Plateau. Chapter three deals with vegetation dynamics and resource use. It reviews ecological site classification and mapping of the central Borana Plateau and aspects of environmental change induced by pastoral land use. The fourth chapter reviews aspects of Borana household composition and economy as they pertain to average rainfall years during the 1980s. Related topics include labour allocation, livestock marketing, milk processing, dairy marketing and cultivation. Chapter five highlights work from experimental trials and producer surveys concerning livestock management and productivity in the Borana system. Chapter six reviews the impacts of the 1983-84 drought on the Borana production system and outlines key tactics that households used in response to drought. Development intervention concepts is the topic of chapter 7. The last chapter summarises key ideas from previous chapters into a concise development strategy for the southern rangelands