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991.
Combinatorial interaction testing (CIT) is a cost-effective sampling technique for discovering interaction faults in highly-configurable
systems. Constrained CIT extends the technique to situations where some features cannot coexist in a configuration, and is
therefore more applicable to real-world software. Recent work on greedy algorithms to build CIT samples now efficiently supports
these feature constraints. But when testing a single system configuration is expensive, greedy techniques perform worse than
meta-heuristic algorithms, because greedy algorithms generally need larger samples to exercise the same set of interactions.
On the other hand, current meta-heuristic algorithms have long run times when feature constraints are present. Neither class
of algorithm is suitable when both constraints and the cost of testing configurations are important factors. Therefore, we
reformulate one meta-heuristic search algorithm for constructing CIT samples, simulated annealing, to more efficiently incorporate
constraints. We identify a set of algorithmic changes and experiment with our modifications on 35 realistic constrained problems
and on a set of unconstrained problems from the literature to isolate the factors that improve performance. Our evaluation
determines that the optimizations reduce run time by a factor of 90 and accomplish the same coverage objectives with even
fewer system configurations. Furthermore, the new version compares favorably with greedy algorithms on real-world problems,
and, though our modifications were aimed at constrained problems, it shows similar advantages when feature constraints are
absent. 相似文献
992.
A problem of allocating resources of a grid to workflow applications is considered. The problem consists, generally, in allocating
distributed grid resources to tasks of a workflow in such a way that the resource demands of each task are satisfied. Grid
resources are divided into computational resources and network resources. Computational tasks and transmission tasks of a
workflow are distinguished. We present a model of the problem, and an algorithm for finding feasible resource allocations.
A numerical example is included, showing the importance of the resource allocation phase on a grid. Some conclusions and directions
for future research are given. 相似文献
993.
The carry-over effects value is one of the various measures one can consider to assess the quality of a round robin tournament
schedule. We introduce and discuss a new, weighted variant of the minimum carry-over effects value problem. The problem is
formulated by integer programming and an algorithm based on the hybridization of the Iterated Local Search metaheuristic with
a multistart strategy is proposed. Numerical results are presented. 相似文献
994.
The basic scheduling problem we are dealing with is the following. There are n jobs, each requiring an identical execution time. All jobs have to be processed on a set of parallel machines. Preemptions
can be either allowed or forbidden. The aim is to construct a feasible schedule such that a given criterion is minimized.
In this paper, we survey existing approaches for the problem class considered. 相似文献
995.
This paper is the first attempt to successfully design efficient approximation algorithms for the single-machine weighted
flow-time minimization problem when jobs have different release dates and weights equal to their processing times under the
assumption that one job is fixed (i.e., the machine is unavailable during a fixed interval corresponding to the fixed job).
Our work is motivated by an interesting algorithmic application to the generation of valid inequalities in a branch-and-cut
method. Our analysis shows that the trivial FIFO sequence can lead to an arbitrary large worst-case performance bound. Hence,
we modify this sequence so that a new 2-approximation solution can be obtained for every instance and we prove the tightness
of this bound. Then, we propose a fully polynomial-time approximation algorithm with efficient running time for the considered
problem. Especially, the complexity of our algorithm is strongly polynomial. 相似文献
996.
Consider an m-machine production line for processing identical parts served by a mobile robot. The problem is to find the minimum cycle
time for 2-cyclic schedules, that is, schedules in which exactly two parts enter and two parts leave the production line during
each cycle. This work treats a special case of the 2-cyclic robot scheduling problem when the robot route is given and operation
durations are chosen from prescribed intervals. A strongly polynomial algorithm of time complexity O(m
8log m) is proposed. 相似文献
997.
We consider the problem of nonpreemptively scheduling a set of n jobs with equal processing times on m parallel machines so as to minimize the makespan. Each job has a prespecified set of machines on which it can be processed,
called its eligible set. We consider the most general case of machine eligibility constraints as well as special cases of nested and inclusive eligible
sets. Both online and offline models are considered. For offline problems we develop optimal algorithms that run in polynomial
time, while for online problems we focus on the development of optimal algorithms of a new and more elaborate structure as
well as approximation algorithms with good competitive ratios. 相似文献
998.
999.
As manufacturing environments are getting distributed and increasing in size, the related virtual environments are getting
larger and more closely networked together. This trend has led to a new paradigm—large-scale virtual manufacturing environment
(LSVME). It supports networked and distributed virtual manufacturing to meet manufacturing system requirements. Since it contains
a large number of virtual components, an effective data structure and collaborative construction methodology are needed. A
metaearth architecture is proposed as the data structure for representing LSVME. This architecture consists of virtual space
layer, mapping layer, library layer and ontology layers, which describe interaction among virtual components and has the ability
to analyze the characteristics of virtual environment. In addition, it increases reusability of virtual components and supports
self-reconfiguration for manufacturing simulation. A heuristic construction method based on graph theory is proposed using
this architecture. It prevents redundant design of virtual components and contributes to an effective construction scheduling
technique for collaborative designers. 相似文献
1000.