16824799
A heuristic method for self‐healing ring design in a single‐homing cluster
In this paper, we consider a SONET (Synchronous Optical NETwork) USHR (Uni‐directional Self‐Healing Ring) design problem for a single‐homing cluster, i.e., a cluster with a single designated hub. The problem is formulated as a nonlinear integer programming problem and a branch and bound heuristic method based on the Lagrangian relaxation and subgradient optimization technique is proposed to handle the problem. In solving any ring design problem, we should deal with two different aspects of the ring design, namely, the ring routing aspect and the ring loading aspect. Both of these two aspects are well integrated and represented in our model. Such an integrated formulation has not been proposed in the existing literature mainly due to its computationally intractable complexity. In order to cope with such complexity, a preprocessing technique for reducing the complexity and several branch and bound strategies are proposed. The efficiency of the proposed method is tested through computational experiments. For the computational experiments, test problems are generated using the data obtained from the actual topologies in Seoul, Korea. The computational experiments show that the proposed method yields near‐optimum designs within reasonable computation time.
7967901
The effect of machine availability on the worst-case performance of LPT
We consider the makespan minimization parallel machine scheduling problem where each machine may be unavailable for a known time interval. For this problem, we investigate how the worst-case behavior of the longest processing time first algorithm (LPT) is affected by the availability of machines. In particular, for given m machines, we analyze the cases where arbitrary number, λ, ranging from one to m - 1, machines are unavailable simultaneously. Then, we show that the makespan of the schedule generated by LPT is never more than the tight worst-case bound of 1 + ½ ⌊m/(m - λ)⌋ times the optimum makespan.
15655721
The Worst-case Analysis of the MULTIFIT Algorithm for Scheduling Nonsimultaneous Parallel Machines
Abstract In this paper we consider the nonsimultaneous multiprocessor scheduling problem, or NMSP for short. The NMSP is a makespan minimization scheduling problem which involves the nonpreemptive assignment of independent jobs on m parallel machines with different starting times. It is well known that the longest processing time (LPT) algorithm and the modified LPT(MLPT) algorithm yield schedules with makespans bounded by 3 2 − 1 2m and 4/3 times the optimum makespan, respectively. In this paper, we show that the best known worst-case performance bound, 4/3 of the MLPT, is tight by constructing a worst-case example. Then, we employ the bin-packing heuristic algorithm called the MULTIFIT to solve the NMSP and show that the makespan of the schedule generated by the MULTIFIT algorithm is bounded by 9/7+2−k times the optimum makespan, where k is the selected number of the major iterations in the MULTIFIT. This worst-case bound of the MULTIFIT algorithm is, so far, the best bound for the NMSP and the tightness of the bound is still an open question.
18088728
Order Consolidation for Batch Processing
We consider the batch processing of orders where either whole or part of a single order or a specific pair of different orders may be grouped in a batch with a fixed capacity. The problem can be modelled by a graph G = (V,E), where each node v$${\in}$$V corresponds to an order, its weight w(v) corresponds to the amount of ordered quantity and a pair of orders, say u and v may be grouped in a batch if there exists the edge (u,v) $${\in}$$E. The objective is to maximize the number of batches filled up to its capacity $$\lambda$$. In this paper, we prove that the problem is NP-hard and, moreover, that no PTAS exists unless P = NP. Then, an optimal algorithm is developed with running time O(|V|log |V|) for the special case when G is a tree.
18938523
A two-dimensional vector packing model for the efficient use of coil cassettes
We consider the problem of efficiently packing steel products, known as coils, into special containers, called cassettes for shipping. The objective is to minimize the number of cassettes used for packing all the given coils where each cassette has capacity limits on both total payload weight and size. We model this problem as a two-dimensional vector packing problem and propose a heuristic. We also analyze the worst-case performance of the proposed algorithm under a special condition which, in fact, holds for the particular real-world case that we handled. Our computational experiment with real production data shows that the proposed algorithm performs quite satisfactorily in practice.
28693312
A new architecture for motion-compensated image coding
Abstract In motion-compensated image coding (MCIC), the block matching algorithm requires a very complex computational procedure. To overcome this problem, several fast search procedures have been proposed. However, the resultant errors for these procedures may be too large unless small displacement is assumed. In order to reduce the computational complexity and preserve the quality of the original image, a new architecture for MCIC without the small displacement assumption is proposed in this paper. Based on a so-called characteristic mapping, certain important features of the block will be extracted and matched in the space of features. Hence, the procedure of matching any two blocks is very much simplified and the time required is drastically reduced. Moreover, the simulation results indicate that its performance is superior to those fast search procedures based on the error between the reconstructed image and the original one. This property will result in low bit rates for transmitting the error frame.
46054321
A 2D interactive parser of iconic languages
In this paper we give algorithms for the construction of a 2D interactive parser which helps a user to construct correct two-dimensional iconic sentences according to positional LALR grammars. At each step of the parsing process the user is provided with a feasible set of icons. Moreover, the areas on the screen where each icon in the set may be placed are highlighted. In this way both syntactic and structural errors are avoided.<<ETX>>
5720205
Using Relevance Feedback in Content-Based Image Metasearch
MetaSeek is an image metasearch engine developed to explore the querying of large, distributed, online visual information systems. The current implementation integrates user feedback into a performance-ranking mechanism. MetaSeek selects and queries the target image search engines according to their success under similar query conditions in previous searches. The current implementation keeps track of each target engine's performance by integrating user feedback for each visual query into a performance database. We begin with a review of the issues in content-based visual query, then describe the current MetaSeek implementation. We present the results of experiments that evaluated the implementation in comparison to a previous version of the system and a baseline engine that randomly selects the individual search engines to query. We conclude by summarizing open issues for future research.
40375618
A Visual Optimization Specification Language
43054097
Unifying multi-paradigms in software system design
Large software systems are often aimed to deal with problems of multi-application domains or disciplines, where each class of problems has its own defining features, difficulties and emphases. No existing computation model or design paradigm is appropriate for all varieties of problems faced in software design. A unification of existing computation paradigms is thus necessary to accommodate the diverse needs in system design. In this paper, the authors propose a framework based on the notions of logical entity abstraction and instantiation (LEAI), which enables a user to select appropriate computation paradigms to design various parts (or subsystems) of a software system, and to compose the parts into a integrated system. An example is given to illustrate the application of the framework.<<ETX>>