An enhanced ant colony optimization (EACO) applied to capacitated vehicle routing problem

In this paper, an enhanced ant colony optimization (EACO) is proposed for capacitated vehicle routing problem. The capacitated vehicle routing problem is to service customers with known demands by a homogeneous fleet of fixed capacity vehicles starting from a depot. It plays a major role in the field of logistics and belongs to NP-hard problems. Therefore, it is difficult to solve the capacitated vehicle routing problem directly when solutions increase exponentially with the number of serviced customers. The framework of this paper is to develop an enhanced ant colony optimization for the capacitated vehicle routing problem. It takes the advantages of simulated annealing and ant colony optimization for solving the capacitated vehicle routing problem. In the proposed algorithm, simulated annealing provides a good initial solution for ant colony optimization. Furthermore, an information gain based ant colony optimization is used to ameliorate the search performance. Computational results show that the proposed algorithm is superior to original ant colony optimization and simulated annealing separately reported on fourteen small-scale instances and twenty large-scale instances.     

Examination of characteristics method with cubic interpolation for advection–diffusion equation

In this study, the use of the characteristics method integrated with the Hermite cubic interpolation or the cubic-spline interpolation on the space line or the time line, i.e., the HCSL scheme, the CSSL scheme, the HCTL scheme, and the CSTL scheme, respectively, for solving the advection–diffusion equation is examined. The advection and diffusion of a Gaussian concentration distribution in a uniform flow with constant diffusion coefficient is used to conduct this investigation. The effects of parameters, such as Peclet number, Courant number, and the reachback number, on these four schemes used herein for solving the advection–diffusion equation are investigated. The simulated results show that the CSSL scheme is comparable to the HCSL scheme, and the two schemes seem insensitive to Courant number as compared with the HCTL scheme and the CSTL scheme. With large Peclet number, for small Courant number the HCTL scheme is more accurate than the HCSL scheme and the CSSL scheme. However, for large Courant number the HCTL scheme has worse computed results in comparison with the HCSL scheme and the CSSL scheme. With small Peclet number, the HCTL scheme, the HCSL scheme, and the CSSL scheme have close simulated results. Despite Peclet number, for small Courant number the CSTL scheme is comparable to the HCTL scheme, but for large Courant number the former scheme provides unacceptable simulated results in which very large numerical diffusion is induced due to the effect of the natural endpoint constraint. For large Peclet number the HCSL scheme and the CSSL scheme integrated with the reachback technique can improve simulated results, but for small Peclet number the HCSL scheme and the CSSL scheme seem not to be influenced by increasing the reachback number.     

A new LMI-based approach to relaxed quadratic stabilization of T-S fuzzy control systems

This paper proposes a new quadratic stabilization condition for Takagi-Sugeno (T-S) fuzzy control systems. The condition is represented in the form of linear matrix inequalities (LMIs) and is shown to be less conservative than some relaxed quadratic stabilization conditions published recently in the literature. A rigorous theoretic proof is given to show that the proposed condition can include previous results as special cases. In comparison with conventional conditions, the proposed condition is not only suitable for designing fuzzy state feedback controllers but also convenient for fuzzy static output feedback controller design. The latter design work is quite hard for T-S fuzzy control systems. Based on the LMI-based conditions derived, one can easily synthesize controllers for stabilizing T-S fuzzy control systems. Since only a set of LMIs is involved, the controller design is quite simple and numerically tractable. Finally, the validity and applicability of the proposed approach are successfully demonstrated in the control of a continuous-time nonlinear system.     

AgentGateway: A communication tool for multi-agent systems

With the rapid growth of multi-agent systems (MAS), there is a pressing need to communicate between different MAS. Various MAS communication standards have been proposed. However, MAS is usually designed to meet special need, thus making it difficult to follow a standard. This paper presents a tool called AgentGateway trying to solve this problem using a simple, effective approach. The tool translates messages from one MAS to intermediate XML-based messages, which then are translated to messages for another MAS. AgentGateway is scalable, meaning that new MAS can easily join it. Furthermore, it provides transparent and reliable communication. A prototype is developed that shows communication between two MAS, namely, Java Agent Template Lite (JATLite) and OAA, can be done using this approach.     

The formation of quantum dot structures in 30-pair InGaN/GaN multiple quantum wells after proper thermal annealing treatment

This study systematically investigates the relation between strain energy and quantum dot (QD) formation for 30- pair InGaN/GaN multiple quantum wells (QW) by means of atomic force microscopy and high-resolution transmission electron microscopy. The results show that a higher number of quantum wells induce a higher strain energy and higher density of V-shaped defects, which increases the number of non-radiative centers. However, after thermal annealing, the strain energy accumulated from stacking faults is released and leads to the formation of a QDs structure. The strain energy around the quantum dot structure was calculated using by the NCEM Phase Extensions to the Digital Micrograph. The zone of higher strain energy was observed, which proves that the strain energy is the driving force for the formation of quantum dot structures.     

Multi-heuristic desirability ant colony system heuristic for non-permutation flowshop scheduling problems

Ant colony optimization (ACO) is a novel intelligent meta-heuristic originating from the foraging behavior of ants. An efficient heuristic of ACO is the ant colony system (ACS). This study presents a multi-heuristic desirability ACS heuristic for the non-permutation flowshop scheduling problem, and verifies the effectiveness of the proposed heuristic by performing computational experiments on a well-known non-permutation flowshop benchmark problem set. Over three-quarters of the solutions to these experiments are superior to the current best solutions in relevant literature. Since the proposed heuristic is comprehensible and effective, this study successfully explores the excellent potential of ACO for solving non-permutation flowshop scheduling problems.     

A transportation land use model for rural areas

This paper examines the interaction of transportation and land use in rural areas. The spatial distribution of employment and population is complicated by many factors such as accessibility, income variance, prices, geographical characteristics, and government intervention. This analysis attempts, by using twostage least squares, to isolate the impact on employment and household density of changing transportation cost as measured by accessibility. The results indicate that the accessibility measure used in this study is a sensitive transmitter of changes in a transportation system. The accessibility coefficient derived from a reduced-form equation was used to forecast the impact of a transportation change.The author would like to thank Charles Floyd and Paul Wendt for their helpful comments, and Michael Rowan for his computational work on the accessibility matrix.     

A new simple and reliable method to form a textured Si surface forthe fabrication of a tunnel oxide film

In this work, a textured Si surface was formed with a new simple and reliable method for tunnel oxide fabrication. First, a thin poly-Si layer (12 nm thick) was deposited on Si surface and a 30-nm thick dry oxide film was then grown in O₂ ambient. This oxide film was served as a sacrificial oxide. The poly-Si film and Si substrate were both oxidized during thermal oxidization. After stripping this sacrificial oxide, a textured Si surface was obtained. Tunnel oxide grown on this textured Si surface has asymmetrical J-E characteristics, less interface states generation and better reliability (larger Q_bd ) as compared to those of normal oxide     

Dual damascene advanced interconnects: new copper seed layer enhancement process metrology using ion chromatography

Physical vapor deposition (PVD) copper seeding and subsequent fill by electroplating have become the most attractive technique for the implementation of copper metallization. However, a PVD seed layer provided as a continuous thin film with low resistivity to carry current for the subsequent electroplating process might have limitations of poor step coverage, rough morphology, discontinuity, overhang, and coverage asymmetry. Hence, it is of importance to extend the capability of PVD seed-layer deposition process for future high performance devices. An ion chromatography (IC) method is shown to be capable for electrochemical copper seed layer enhancement (SLE) process metrology. Composition dynamics of fresh and aged SLE bath solutions with an electroplating time up to 66.5 min are measured and analyzed with an IC system. The solution dynamics are found to be significant for electroplated copper film properties, the resistivity and roughness, which are found to be crucial for filling by electroplating the sub-0.2 μm vias and trenches of high aspect ratio. A strong correlation between the ion chromatograms and the electroplated copper film properties is observed.     

Design and implementation of a vision processing system for awalking machine

A vision processing system for a six-legged walking machine, the adaptive suspension vehicle, is presented. The vision-processing system consists of a laser range-finder, and vision computer, a terrain-elevation map, and a guidance computer. The range-finder measures the distances from itself to the objects in the scene. The specially designed vision computer processes the range data into a terrain-elevation form and stores the information with time data in a terrain-elevation map. With the real-time elevation information in the map, the guidance computer can select the best footholds for the walking machine in order to maneuver over rough terrain