6422061
A new branch and bound algorithm for minimizing mean tardiness in two-machine flowshops
Abstract We consider the two-machine flowshop scheduling problem with the objective of minimizing mean tardiness. Presented are several properties that are used to calculate lower bounds on total tardiness of jobs for a given partial sequence and to identify sequences dominated by others. We develop a branch and bound algorithm using these bounds and dominance rule. This algorithm is compared with an existing algorithm on randomly-generated test problems.
205099619
Simulated annealing and genetic algorithms for scheduling products with multi-level product structure
We consider a short-term production scheduling problem in a manufacturing system producing products with multi-level product structure, and their components and subassemblies. The problem is to schedule production of components, subassemblies, and final products with the objective of minimizing the weighted sum of tardiness and earliness of the items. We consider due dates of final products, precedence relationships among items, and processing capacity of the manufacturing system. The scheduling problem is solved with simulated annealing and genetic algorithms, which are search heuristics often used for global optimization in a complex search space. To compare the performance of these algorithms with the finite loading method, which is often used in practice, computational experiments are carried out using randomly generated test problems and results are reported.
35466192
Scheduling on parallel identical machines to minimize total tardiness
This paper focuses on the problem of scheduling n independent jobs on m identical parallel machines for the objective of minimizing total tardiness of the jobs. We develop dominance properties and lower bounds, and develop a branch and bound algorithm using these properties and lower bounds as well as upper bounds obtained from a heuristic algorithm. Computational experiments are performed on randomly generated test problems and results show that the algorithm solves problems with moderate sizes in a reasonable amount of computation time. � 2005 Elsevier B.V. All rights reserved.
21112002
A backward approach in list scheduling algorithms for multi-machine tardiness problems
Abstract List scheduling algorithms are commonly used for multi-machine scheduling problems, especially for those with precedence relationships among operations. In most list scheduling algorithms, operations are scheduled forward. In this paper, we suggest a backward approach in which the operations are scheduled backward. We discuss some details that must be considered when applying the backward approach to problems with due dates and suggest several methods of defining parameters needed in the backward approach. Performance of this approach is tested on job shop problems and identical machine problems with several types of precedence constaints.
9445026
Efficient Uplink Scheduler Architecture of Subscriber Station in IEEE 802.16 System
The IEEE 802.16, broadband fixed wireless access standard, defines four service classes, USG, rtPS, nrtPS and BE on high speed wireless networks. To guarantee the QoS requirement of these classes, the subscriber station and base station require scheduling architecture and algorithm. However, the IEEE 802.16 does not define any scheduling architecture or algorithm, and the most existing scheduling mechanisms only focus on working at the BS. In this paper, we propose two types of scheduling architecture working at the SS. In the one-level scheduler, we use a flow queue and class queue by differentiating flows with their class priority. The two-level scheduler can provide more organized QoS service with complementing the one-level scheduler. Adapting these architectures makes scheduler efficiently control all types of traffic defined in the IEEE 802.16. In the proposed architecture, any scheduling algorithms such as SCFQ and EDF can be applied. We evaluate the proposed scheduling architecture by simulation. The results of the simulation show that our proposed architecture can use the bandwidth efficiently.
20557981
3-D Pose Tracking of the Car Occupant
Although airbags in the car play an important role for the safety of occupants, in fact, many peoples have been injured or killed by the deployment of airbags themselves. Such conventional airbags are deployed by the shock sensors. As an alternative approach, a vision-based smart airbag system could be promising. This paper describes a new method by which 3-D pose of the car occupant can be recognized. We combine 2-D head tracking information with a disparity map of the occupant for 3-D pose tracking. Result shows that the system can locate the head position around the passenger's seat with a real-time basis.
11890469
Modeling Dynamic Perceptual Attention in Complex Virtual Environments
An important characteristic of a virtual human is the ability to direct its perceptual attention to entities and areas in a virtual environment in a manner that appears believable and serves a functional purpose. In this paper, we describe a perceptual attention model that mediates top-down and bottom-up attention processes of virtual humans in order for the virtual human to efficiently select important information with limited sensory capability within complex virtual environments.
40331728
Efficient 2-D Convolution Algorithm with the Single-Data Multiple Kernel Approach
Abstract A fast implementation of convolution operation is described. The implementation takes advantage of various properties of commonly used kernels. First, the kernel elements are analyzed and rearranged, grouping the kernel elements of the same absolute value together and arranging trivial multiplication cases separately. Then the sequence of computing convolution sums is modified so that all the kernel elements could be multiplied by the same data element at each step. This new algorithm significantly reduces the number of multiplication operations for most widely used kernels. Our experiment shows that the performance improvement of two to seven over the direct implementation is achievable for most kernels. The required overhead (extra memory and preprocessing) is proportional to the kernel size and is negligible.
15690106
Genetic Search For Fixed Channel Assignment Problem With Limited Bandwidth
We propose a hybrid genetic algorithm for the fixed channel assignment problem with limited bandwidth. A local optimization algorithm was devised to enhance the genetic algorithm's fine-tunning. In a matrix representation, the local optimization algorithm improves on a chromosome by horizontal and vertical moves of channels. The crossover is directly performed on two-dimensional matrices. Experimental results showed dramatic improvement against previous works.