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.
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.
206416394
An Intelligent Image Database System
A prototype intelligent image database system (IIDS) that is based on a novel pictorial data structure is presented. This prototype system supports spatial reasoning, flexible image information retrieval, visualization, and traditional image database operations. A pictorial data structure, based on 2-D strings, provides an efficient means for iconic indexing in image database systems and spatial reasoning. The modular design of IIDS facilitates its implementation. Further extensions of the prototype system are discussed. >
40664162
A Visual Language Compiler
The SIL-ICON compiler is a software system for the specification, interpretation, prototyping, and generation of icon-oriented systems. The system design of the SIL-ICON compiler is presented. The icon system G, the icon dictionary ID, the operator dictionary OD, and the extended task action grammar ETAG are described. An application example to design a text editor using the Heidelberg icon set is also presented in detail. >
6609571
Efficient Techniques for Feature-Based Image/Video Access and Manipulation
Efficient, effective methods for indexing, searching, and retrieving images and videos from large archives are critical techniques required in visual information systems (VIS) applications. Users need a more powerful method for searching images than just traditional text-based query (e.g., keywords). Manual creation of keywords is too time-consuming for many practical applications. Subjective descriptions based on users’ input will be neither consistent nor complete. Also, the vocabulary used in describing visual contents is usually domain specific.
44477744
Efficient selection of scheduling rule combination by combining design of experiment and ordinal optimization-based simulation
In a fab with heterogeneous machine groups, the number of scheduling policies grows in a combinatorial way because each machine group has its specific dispatching rules. In this paper, we design a fast simulation methodology by an innovative combination of the notions of ordinal optimization (OO) and design of experiments (DOE) to efficiently select a good scheduling policy for fab operation, Instead of finding the exact performance among scheduling policies, our approach compares their relative orders of performance to a specified level of confidence. The DOE method is exploited to largely reduce the number of scheduling policies to be evaluated by the OO-based simulation. Simulation results of applications to scheduling wafer fabrications show that most of the OO-based DOE simulations require 2 to 3 orders of magnitude less computation time than those of traditional approach, and the speedup is up to 7,000 times in certain cases.
428530
Scalable MPEG2 Video Servers with Heterogeneous QoS on Parallel Disk Arrays
In this paper we focus on the video storage unit of a video server. We present a new, flexible data placement strategy for independent parallel disk arrays. The trade-off between utilization efficiency and interactive delay is investigated for this data placement strategy. Based on this trade-off, we show the advantage of video servers supporting a range of interactivity QoS. For our data placement strategy, we show that using scalable video improves the utilization and interactivity performance of a video server. We use three-layer, scalable MPEG2 digital video to support resolution QoS at a video server. Finally, we show that the data placement strategy reduces the complexity of admission control at the video server to that of a single disk system.