The open shop scheduling problem with a given sequence of jobs on one machine

The paper considers the open shop scheduling problem to minimize the make-span, provided that one of the machines has to process the jobs according to a given sequence. We show that in the preemptive case the problem is polynomially solvable for an arbitrary number of machines. If preemption is not allowed, the problem is NP-hard in the strong sense if the number of machines is variable, and is NP-hard in the ordinary sense in the case of two machines. For the latter case we give a heuristic algorithm that runs in linear time and produces a schedule with the makespan that is at most 5/4 times the optimal value. We also show that the two-machine problem in the nonpreemptive case is solvable in pseudopolynomial time by a dynamic programming algorithm, and that the algorithm can be converted into a fully polynomial approximation scheme. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 705–731, 1998

Simulating one of the CIB W14 round robin test cases using the SMARTFIRE fire field model

Numerical predictions produced by the SMARTFIRE fire field model are compared with experimental data. The predictions consist of gas temperatures at several locations within the compartment over a 60 min period. The test fire, produced by a burning wood crib attained a maximum heat release rate of approximately 11MW. The fire is intended to represent a nonspreading fire (i.e. single fuel source) in a moderately sized ventilated room. The experimental data formed part of the CIB Round Robin test series. Two simulations are produced, one involving a relatively coarse mesh and the other with a finer mesh. While the SMARTFIRE simulations made use of a simple volumetric heat release rate model, both simulations were found capable of reproducing the overall qualitative results. Both simulations tended to overpredict the measured temperatures. However, the finer mesh simulation was better able to reproduce the qualitative features of the experimental data. The maximum recorded experimental temperature (12141C after 39 min) was over-predicted in the fine mesh simulation by 12%. (C) 2001 Elsevier Science Ltd. All rights reserved.

Reviews: Private Passions with Robin Wilson [Radio review]

Tony Mann reviews Robin Wilson's appearance as Michael Berkeley's guest on Private Passions. Broadcast on BBC Radio 3, on 9 September 2007.

Multiple-locus sequence typing analysis of Bacillus thuringiensis recovered from the phylloplane of clover (Trifolium hybridum) in vegetative form

The chromosomal genotype, as judged by multi locus sequence typing, and the episomal genotype, as judged by plasmid profile and cry gene content, were analyzed for a collection of strains of Bacillus thuringiensis. These had been recovered in vegetative form over a period of several months from the leaves of a small plot of clover (Trifolium hybridum). A clonal population structure was indicated, although greater variation in sequence types (STs) was discovered than in previous collections of B. cereus/B. thuringiensis. Isolates taken at the same time had quite different genotypes, whereas those of identical genotypes were recovered at different times. The profiles of plasmid content and cry genes generally bore no relation to each other nor to the STs. Evidently, although relatively little recombination was occurring in the seven chromosomal genes analyzed, a great deal of conjugal transfer, and perhaps recombination, was occurring involving plasmids. A clinical diarrheal isolate of B. cereus and the commercial biopesticide strain HD-1 of B. thuringiensis, both included as out-groups, were found to have very similar STs. This further emphasizes the role of episomal elements in the characteristics and differentiation of these two species.

Kinematics and EMG analysis of expert pole vaulter's lower limb during take off phase (P218)

Introduction: The critical phase, in jumping events in track and field, appears to be between touchdown and take-off. Since obvious similarities exist between the take off phase in both long jump and pole vault, numerous 3D kinematics and electromyographic studies have only looked at long jump. Currently there are few detailed kinematics electromyographic data on the pole vault take-off phase. The aim of this study was therefore to characterise kinematics and electromyographic variables during the take-off phase to provide a better understanding of this phase in pole vaulting and its role in performance outcome. Material and methods: Six pole-vaulters took part in the study. Kinematics data were captured with retro reflective markers fixed on the body. Hip, knee and ankle angle were calculated. Differential bipolar surface electrodes were placed on the following muscles of the take-off leg: tibialis anterior, lateral gastrocnemius, vastus lateralis, rectus femoris, bicep femoris and gluteus maximus. EMG activity was synchronously acquired with the kinematic data. EMG data were rectified and smoothed using a second order low pass Butterworth Bidirectional filter (resulting in a 4th order filter) with a cut-off frequency of 14 Hz. Results: Evolution of hip, knee and ankle angle show no significant differences during the last step before touchdown, the take-off phase and the beginning of fly phase. Meanwhile, strong differences in EMG signal are noted inter and intra pole vaulter. However for a same subject the EMG activities seem to converge to some phase locked point. Discussion: All pole vaulters have approximately the same visible coordination This coordination reflects a different muscular control among pole vaulters but also for a considered pole vaulter. These phase locked point could be considered as invariant of motor control i.e. a prerequisite for a normal sequence of the movement and performance realization.