The problem of placing wireless transmitters to meet particular objectives, such as coverage and cost, has proven to be NP-hard. Furthermore, the heterogeneity of wireless networks makes the problem more intractable to deal with. This paper presents a novel multiobjective variable-length genetic algorithm to solve this problem. One does not need to determine the number of transmitters beforehand; the proposed algorithm simultaneously searches for the optimal number, types, and positions of heterogeneous transmitters by considering coverage, cost, capacity, and overlap. The proposed algorithm can achieve the optimal number of transmitters with coverage exceeding 98% on average for six benchmarks. These preferable experimental results demonstrate the high capability of the proposed algorithm for the wireless heterogeneous transmitter placement problem.

The multiplex PCR experiment is to amplify multiple regions of a DNA sequence at the same time by using different primer pairs. Designing feasible primer pairs for multiplex PCR is a tedious task since there are too many constraints to be satisfied. In this paper, a new method for multiplex PCR primer design strategy using genetic algorithm is proposed. The proposed algorithm is able to find a set of suitable primer pairs more efficient and uses a MAP model to speed up the examination of the specificity constraint that is important for gene family sequences. The dry-dock experiment shows that the proposed algorithm finds several sets of primer pairs of gene family sequences for multiplex PCR that not only obey the design properties, but also have specificity.

MOTIVATION: Before performing a polymerase chain reaction experiment, a pair of primers to clip the target DNA subsequence is required. However, this is a tedious task as too many constraints need to be satisfied. Various kinds of approaches for designing a primer have been proposed in the last few decades, but most of them do not have restriction sites on the designed primers and do not satisfy the specificity constraint. RESULTS: The proposed algorithm imitates nature's process of evolution and genetic operations on chromosomes in order to achieve optimal solutions, and is a best fit for DNA behavior. Experimental results indicate that the proposed algorithm can find a pair of primers that not only obeys the design properties but also has a specific restriction site and specificity. Gel electrophoresis verifies that the proposed method really can clip out the target sequence. AVAILABILITY: A public version of the software is available on request from the authors.

Due to the entry of Taiwan into WTO and the recently liberalized Petroleum Management Law, the oil market in Taiwan is liberalized and thus is becoming more competitive. However, the space limitation and the residents' increasing awareness of environmental protection issues in the island make international vendors unavoidably have to rent tanks from domestic oil companies. In order to help the leaseholder maximize revenue by increasing the availability of tanks, an efficient maintenance scheduling is needed. This paper introduces a tabu-based genetic algorithm (TGA) and its implementation for solving a real-world maintenance scheduling problem of oil storage tanks. TGA incorporates a tabu list to prevent inbreeding and utilizes an aspiration criterion to supply moderate selection pressure so that the selection efficiency is improved, and the population diversity is maintained. The experimental results validate that TGA outperform GA in terms of solution quality and convergence efficiency. Keywords: Tabu-based genetic algorithm, maintenance scheduling, tabu search, genetic algorithm.

The genetic algorithm (GA) is a well-known heuristic optimization algorithm. However, it suffers from the serious problem of premature convergence, which is caused mainly by the population diversity decreasing in evolution. The authors propose a novel algorithm, called TGA, which integrates the memory structure and search strategy of Tabu Search (TS) with GA. As such, the selection efficiency is improved and the population diversity is maintained by incorporating the regeneration operator. The traveling salesman problem is used as a benchmark to evaluate TGA and compare it with GA and TS. Experimental results show that TGA achieves better performance than GA and TS in terms of both convergence speed and solution quality.

In this paper we propose a dynamic scheduling heuristic for allocating task graphs onto Internet-centric metacomputing systems. This proposed algorithm, which is called the Dynamic Grouping Scheduling (DGS), differs from conventional algorithms in three respects. First, DGS employs a dynamic task grouping strategy to determine task computational cast. Second, this algorithm estimates the competence of processors for unscheduled tasks at each scheduling step. Third, the proposed scheme takes the fluctuations of power weight for processors into consideration. Experimental results show that the proposed DGS performs better than the competing scheduling schemes under the effects of varying power weights of processors.

We propose a heuristic scheduling algorithm, called Competence Based Method (CBM), to dynamically distribute workload for the task allocation problem in a Web/Java based computing environment. CBM is designed to meet four properties of Web computing: heterogeneity, scalability, centralization, and non-dedication host. CBM can be applied to both independent and dependent links scheduling problems. Compared with the competing algorithms, the experimental results show that the proposed CBM performs faster in parallel time and is close to the optimal.

In this article, we describe a distributed visual reasoning system for intelligent information retrieval on the Web. The system is an integration of visual programming, the Web browser, Java applets, inference engine, and database servers. It provides users with a visual programming interface and acts as a mediator to coordinate messages passing among the Web clients, inference engine, and database servers for the information retrieval. A Web server is used to store the required Web page and to provide the required configuration functions for the system. Through the Web client a user can download all required Java classes, information, and the visual programming interface agent through the HTTP protocol, then activate the functions of Java applets. By composing visual sentences and providing parameters in the visual programming interface a user can extract the required information. A distributed communication model is proposed to give better communication speed and a more reliable connection. We use a financial diagnosis as one of many potential applications to illustrate our system.

Facial model reconstruction and surgical simulation are essential to plastic surgery in today's medicine. Both can help surgeons to design appropriate repair plans and procedures prior to actual surgery. In this paper, we exploit a metamorphosis technique in our new design. First, using metamorphosis and vision techniques, we can establish three-dimensional facial models from a given photo. Second, we design several morphing operators, including augmentation, cutting, and lacerating. Experiments show that the proposed algorithms can successfully create acceptable facial models and generate realistically visual effects of surgical simulation.

We describe a distributed robust image mosaics system that is robust to outlier and is better in computation efficiency. The system integrates a Web-based user interface, a robust image mosaic, and a distributed computing model. In robust image mosaics, we combine both feature-based and correlation-based approaches for image registration, and then incorporate a skipped mean estimator with Levenberg-Marquardt method for robust nonlinear parameter estimation. The distributed comparing model is used to speed up the computation of the global processing of image mosaics on a network of workstations. Load balancing strategies are proposed to improve the efficiency of parallel computation under uneven load situation. Experimental results show that our system is indeed robust and has significantly speedup in computation.

In this paper, we analyze the requirements for a Web‐based collaborative infrastructure within a virtual world. Additionally, we combine several tools and methodologies to propose a flexible and fluid collaborative environment using Java language to create a VRML scene graph. The proposed prototype aims at four aspects: a shared workspace of scene editor, an active entity composition algorithm in Java, collaborative control in the multi‐user environment, and access control mechanism toward the shared data.

In this paper, we present a new stroke extraction algorithm that integrates all levels of contour information including boundary points, dominant points, corner points, segments, cross section sequence graph, character structure to extract strokes of Chinese characters. In the algorithm, first, the boundary points are extracted, then the dominant and corner points are detected. Third, the character structure including singular and regular regions are extracted by the contour information and a modified cross section sequence graph (CSSG). Finally, a Bezier curve taking dominant points and corner points as inputs is used to check the continuity of strokes. Experimental results show that the proposed algorithm can correctly extract the strokes up to 95% from a printed and handwritten test samples based on the human perception. This research provides a solid basis for the structural matching of Chinese characters.

Many applications on the Web require active processing and co-ordination of services. In this paper we describe the design of a distributed 3D animation system built by integrating the Java language, parallel virtual machine (PVM) software, a collaborative mechanism, 3D computer graphics and the Web technologies. To achieve collaborative co-operation and functional independence, session control and system agents are devised in this system. In particular, we propose a simplified collaborative group definition, collaborative policies, and the state of participants to dynamically manage participants in this Web-based distributed environment. Based on our proposed mechanism, the server can efficiently determine the status of collaboration activities. © 1997 John Wiley & Sons, Ltd.