title: A hybrid genetic algorithm for a loading problem in flexible manufacturing systems

authors: Basnet, Chuda

subjects: flexible manufacturing systems

abstract: One of the operating decisions involved in the scheduling of flexible manufacturing systems (FMS) is that of loading the FMS. Given a pool of jobs, which can be processed on alternate machines and alternate tools, the scheduler has to decide on the allocation of tools and machines to the different jobs. Various versions of this problem have appeared in the literature. We consider the version where jobs are selected for processing in a FMS in a planning horizon, operations for these jobs are assigned to machines, and corresponding tools are allocated to the slots in the machines. The objective is to minimise system unbalance. A hybrid genetic algorithm is presented that addresses this problem. Computational comparison between the genetic algorithm and previous algorithms is presented.

text: A hybrid genetic algorithm for a loading problem in flexible manufacturing systems One of the operating decisions involved in the scheduling of flexible manufacturing systems (FMS) is that of loading the FMS. Given a pool of jobs, which can be processed on alternate machines and alternate tools, the scheduler has to decide on the allocation of tools and machines to the different jobs. Various versions of this problem have appeared in the literature. We consider the version where jobs are selected for processing in a FMS in a planning horizon, operations for these jobs are assigned to machines, and corresponding tools are allocated to the slots in the machines. The objective is to minimise system unbalance. A hybrid genetic algorithm is presented that addresses this problem. Computational comparison between the genetic algorithm and previous algorithms is presented.

year: 2011

title: Towards Internet scale simulation

authors: McGregor, Anthony James

subjects: Discrete Event Simulation

abstract: Simulation of the Internet has long been understood to be very challenging mostly because of its scale, diversity and the lack of detailed knowledge of many of its components. However, two recent developments (macroscopic topology discovery and large memory servers) mean that some of these problems are now more tractable. Although problems like the lack of detailed link information remain, models are are useful for some problems that require an understanding of how an application interacts with the Internet as a whole. The paper presents is-0, an Internet Simulator. is-0 derives its model of Internet topology directly from the output of an Internet topology mapping project. Efficient design allows is-0 to simulate packet-by-packet, hop-by-hop behaviour at Internet scale. Validation of is-0, an example application and performance measurements are included.

text: Towards Internet scale simulation Simulation of the Internet has long been understood to be very challenging mostly because of its scale, diversity and the lack of detailed knowledge of many of its components. However, two recent developments (macroscopic topology discovery and large memory servers) mean that some of these problems are now more tractable. Although problems like the lack of detailed link information remain, models are are useful for some problems that require an understanding of how an application interacts with the Internet as a whole. The paper presents is-0, an Internet Simulator. is-0 derives its model of Internet topology directly from the output of an Internet topology mapping project. Efficient design allows is-0 to simulate packet-by-packet, hop-by-hop behaviour at Internet scale. Validation of is-0, an example application and performance measurements are included.

year: 2011

title: Significance of an early date from an adzed tree stump in Northland

authors: Higham, Thomas F.G.

abstract: Ogle, Jones, Sutton and Wallace (1998) have recently investigated the radiocarbon dating of a tree stump ('Ogle's stump’) which had evidence of adze marks, near the site of Taumatawhana pa, Houhora, Northland. The conventional radiocarbon age of 938 ± 31 BP was obtained at the Institute of Geological and Nuclear Sciences Ltd (formerly INS) laboratory in 1971. Ogle et al.(1998) considered the 'inbuilt age' of the wood (see McFadgen, 1982) and assessed its contribution to the radiocarbon determination. In this brief paper we re-evaluate that methodology and question the conclusion of Ogle et al. (1998) that the date is reliable. We are particularly concerned with the comparison of the date with an associated radiocarbon result obtained by Elliot et al. (1995) from a nearby site at Lake Taumatawhana, which we think is misleading.

text: Significance of an early date from an adzed tree stump in Northland Ogle, Jones, Sutton and Wallace (1998) have recently investigated the radiocarbon dating of a tree stump ('Ogle's stump’) which had evidence of adze marks, near the site of Taumatawhana pa, Houhora, Northland. The conventional radiocarbon age of 938 ± 31 BP was obtained at the Institute of Geological and Nuclear Sciences Ltd (formerly INS) laboratory in 1971. Ogle et al.(1998) considered the 'inbuilt age' of the wood (see McFadgen, 1982) and assessed its contribution to the radiocarbon determination. In this brief paper we re-evaluate that methodology and question the conclusion of Ogle et al. (1998) that the date is reliable. We are particularly concerned with the comparison of the date with an associated radiocarbon result obtained by Elliot et al. (1995) from a nearby site at Lake Taumatawhana, which we think is misleading.

year: 1998