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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2008.07.024 Byline: Li-Ning Xing (a)(b), Ying-Wu Chen (a), Ke-Wei Yang (a) Keywords: Global optimization; Genetic algorithm; Mutation operator; Immunity operation Abstract: This paper presents a novel mutation operator based on the immunity operation. Also, the selection is integrated into both crossover and mutation operation. Experiments with our approach on many test functions resulted in near-optimal solutions in all cases. In comparison with several other algorithms, our approach achieved improved accuracy. Author Affiliation: (a) Department of Management Science and Engineering, College of Information System and Management, National University of Defense Technology, Changsha 410073, PR China (b) Centre of Excellence for Research in Computational Intelligence and Applications (CERCIA), School of Computer Science, University of Birmingham, Birmingham B15 2TT, UK Article History: Received 15 January 2008; Accepted 18 July 2008 Article Note: (footnote) [star] This work was supported by the National Natural Science Foundation of China (No. 70272002), Graduate Student Public Sending Abroad Project for Constructing High-level University of China Scholarship Council, Innovative Foundation for Excellent Graduate Student of National University of Defense Technology.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.regsciurbeco.2008.12.002 Byline: Patricia C. Melo (a), Daniel J. Graham (a), Robert B. Noland (b) Keywords: Meta-analysis; Agglomeration; Productivity; Elasticity Abstract: Although the productivity gains of urban agglomeration economies are generally found to be positive, there is a great deal of variability in the magnitude of reported estimates. This paper undertakes a quantitative review of the empirical literature on agglomeration through a meta-analysis of 729 elasticities taken from 34 different studies. The objective is to make sense of the range of values for agglomeration economies found in the literature by identifying some key characteristics that affect the magnitude of the results obtained. Our analysis confirms that study characteristics do matter. In particular, we find that country specific effects, the industrial coverage, the specification of agglomeration economies, and the presence of controls for both unobserved cross-sectional heterogeneity and differences in time-variant labor quality can give rise to large differences in the results reported in the literature. In contrast, correcting for reverse causality of agglomeration does not seem to produce noticeable changes in the size of urban agglomeration estimates. We also test for publication bias and find some evidence supporting the presence of positive reporting bias. The findings support the intuition that agglomeration estimates for any particular empirical context may have little relevance elsewhere. Author Affiliation: (a) Centre for Transport Studies, Dept of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK (b) Alan M. Voorhees Transportation Center, Edward J. Bloustein School of Planning and Public Policy, Rutgers University, New Brunswick, NJ 08901, United States Article History: Received 14 July 2008; Revised 12 December 2008; Accepted 15 December 2008 Article Note: (footnote) [star] We would like to thank Henri L. F. de Groot (VU Amsterdam) for his helpful comments and suggestions.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2008.09.005 Byline: Seong-Rin Lim (a), Jong Moon Park (b) Abstract: Synthesis of distributed wastewater treatment plants (WTPs) has focused on cost reduction, but never on the reduction of environmental impacts. A mathematical optimization model was developed in this study to synthesize existing distributed and terminal WTPs into an environmentally friendly total wastewater treatment network system (TWTNS) from a life cycle perspective. Life cycle assessment (LCA) was performed to evaluate the environmental impacts of principal contributors in a TWTNS. The LCA results were integrated into the objective function of the model. The mass balances were formulated from the superstructure model, and the constraints were formulated to reflect real wastewater treatment situations in industrial plants. A case study validated the model and demonstrated the effect of the objective function on the configuration and environmental performance of a TWTNS. This model can be used to minimize environmental impacts of a TWTNS in retrofitting existing WTPs in line with cleaner production and sustainable development. Author Affiliation: (a) Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Avenue, St. Paul, MN 55108, USA (b) Advanced Environmental Biotechnology Research Center, Department of Chemical Engineering, School of Environmental Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, South Korea Article History: Received 16 November 2007; Revised 18 August 2008; Accepted 19 September 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2007.09.021 Byline: Wei Feng (a), Masataka Umemura (b) Keywords: Two-class and two-server queueing model; Nonpreemptive priority; Waiting time; Steady-state distribution; Blocking probability Abstract: In this paper, we analyze a finite buffer queueing model with two servers and two nonpreemptive priority service classes. The arrival streams are independent Poisson processes, and the service times of the two classes are exponentially distributed with different means. One of the two servers is reserved exclusively for one class with high priority and the other server serves the two classes according to a nonpreemptive priority service schedule. For the model, we describe its dynamic behavior by a four-dimensional continuous-time Markov process. Applying recursive approaches we present the explicit representation for the steady-state distribution of this Markov process. Then, we calculate the Laplace-Stieltjes Transform and the steady-state distribution of the actual waiting times of two classes of customers. We also give some numerical comparison results with other queueing models. Author Affiliation: (a) Department of Engineering Physics, Electronics and Mechanics, Graduate School of Engineering, Nagare College, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan (b) Development and Planning Department, Toyota Motor Corporation, Toyota-cho, Toyota 471-8571, Japan Article History: Received 29 March 2005; Accepted 9 September 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2008.01.032 Byline: Wade D. Cook (a), Larry M. Seiford (b) Keywords: DEA; Models; Multiplier restrictions; Data variation Abstract: This paper provides a sketch of some of the major research thrusts in data envelopment analysis (DEA) over the three decades since the appearance of the seminal work of [Charnes, A., Cooper, W.W., Rhodes, E.L., 1978. Measuring the efficiency of decision making units. European Journal of Operational Research 2, 429-444]. The focus herein is primarily on methodological developments, and in no manner does the paper address the many excellent applications that have appeared during that period. Specifically, attention is primarily paid to (1) the various models for measuring efficiency, (2) approaches to incorporating restrictions on multipliers, (3) considerations regarding the status of variables, and (4) modeling of data variation. Author Affiliation: (a) Department of Operations Management and Information Systems, Schulich School of Business, York University, Toronto, Ontario, Canada M3J 1P3 (b) Industrial and Operations Engineering, College of Engineering, University of Michigan, Ann Arbor, MI, United States Article History: Received 19 January 2008; Accepted 22 January 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.techfore.2007.02.011 Byline: Yuya Kajikawa, Osamu Usui, Kazuaki Hakata, Yuko Yasunaga, Katsumori Matsushima Keywords: Technology roadmap; Knowledge framework; Cognitive structure; R&D management Abstract: Science and technology (S&T) roadmaps are an attractive tool in R&D management, and have been widely used during the past decade. S&T roadmaps are typically described as a link among concepts such as product, technology, and science. However, it is still not clear what these concepts, especially, S&T, mean. In this work, we propose a framework describing engineering knowledge, and analyze two S&T roadmaps based on the framework. A distinct difference was seen between these roadmaps. According to our results, there are two types of roadmaps with respect to their description levels. One is entity-level description that is seen in environmental science and life science. Another is attribute-level description seen in the manufacturing industries including the semiconductor industry. We assume the attribute-level description of roadmap to be more effective because it enables us to set quantitative goals. Author Affiliation: Institute of Engineering Innovation, School of Engineering, the University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan Article History: Received 8 June 2006; Revised 7 September 2006; Accepted 23 February 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.11.003 Byline: P.G.J. Irwin (a), L.A. Sromovsky (b), E.K. Strong (c), K. Sihra (d), N.A. Teanby (a), N. Bowles (a), S.B. Calcutt (a), J.J. Remedios (e) Keywords: Spectroscopy; Uranus; Titan Abstract: The band model fits of Sihra [1998. Ph.D. Thesis. University of Oxford], subsequently reported by Irwin et al. [2005. Icarus 176, 255-271], to new measurements of low-temperature near-infrared self-broadened methane absorption spectra combined with earlier warmer, longer path measurements of both self- and hydrogen-broadened methane spectra measured by Strong et al. [1993. J. Quant. Spectrosc. Radiat. Transfer 50, 363-429], have been found to contain severe artefacts at wavelengths of very low methane absorption. Although spectra calculated from these new band data appear to be reliable for paths with low to medium absorption, transmissions calculated for long paths of high methane absorption, such as for Uranus, Neptune and Titan are severely compromised. The recorded laboratory transmission spectra of Sihra [1998. Ph.D. Thesis. University of Oxford] and Strong et al. [1993. J. Quant. Spectrosc. Radiat. Transfer 50, 363-429] have thus been refitted with a more robust model and new k-distribution data for both self- and hydrogen-broadened methane absorption derived. In addition, a new model of the temperature dependence of the absorption has been employed that improves the quality of the fit and should also provide more accurate extrapolations to low temperatures. Author Affiliation: (a) Atmospheric, Oceanic, and Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Rd, Oxford, OX1 3PU, UK (b) Space Science and Engineering Center, University of Wisconsin-Madison, 1225 W. Dayton Street, Madison, WI 53706, USA (c) Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario, Canada M5S 1A7 (d) National Radiological Protection Board, Chilton, Didcot, Oxon, OX11 0RQ, UK (e) EOS, Space Research Centre, Department of Physics and Astronomy, University of Leicester, LE11 7RH, UK Article History: Received 12 September 2005; Revised 3 November 2005