scholarly journals Extension of some project scheduling heuristics and their comparison at low and high levels of resource requirement

2021 ◽  
Author(s):  
Mohammad Nematullah
Keyword(s):  
Project Scheduling ◽  
Idle Time ◽  
Priority Rule ◽  
Activity Time ◽  
Resource Constrained ◽  
Resource Requirement ◽  
Low Levels ◽  
High Level ◽  
Over Time ◽  
Better Than

Some of the most frequently used scheduling heuristics for resource constrained projects are Activity Time (ACTIM), Activity Resource (ACTRES) and Resource Over Time (ROT) which are based on Brook's Algorithm (BAG). These heuristics assign resources based upon the priority values of the activities that can be scheduled. In the first part of this study, these heuristics have been modified such that when more than two activities are allowed to be assigned, depending upon the priority rule, that activity is assigned first overriding the priority rule, which, if assigned, will result in minimum resource idle time (MRIT). MRIT is found to improve the performance of these existing heuristics. The second part of the study investigates the performance of these heuristics at high and low levels of resource requirement by each activity. ACTIM was found to perform better than other heuristics at the low level. At the high level, all the heuristics performed equally well.

scholarly journals Extension of some project scheduling heuristics and their comparison at low and high levels of resource requirement

2021 ◽  
Author(s):  
Mohammad Nematullah
Keyword(s):  
Project Scheduling ◽  
Idle Time ◽  
Priority Rule ◽  
Activity Time ◽  
Resource Constrained ◽  
Resource Requirement ◽  
Low Levels ◽  
High Level ◽  
Over Time ◽  
Better Than

Some of the most frequently used scheduling heuristics for resource constrained projects are Activity Time (ACTIM), Activity Resource (ACTRES) and Resource Over Time (ROT) which are based on Brook's Algorithm (BAG). These heuristics assign resources based upon the priority values of the activities that can be scheduled. In the first part of this study, these heuristics have been modified such that when more than two activities are allowed to be assigned, depending upon the priority rule, that activity is assigned first overriding the priority rule, which, if assigned, will result in minimum resource idle time (MRIT). MRIT is found to improve the performance of these existing heuristics. The second part of the study investigates the performance of these heuristics at high and low levels of resource requirement by each activity. ACTIM was found to perform better than other heuristics at the low level. At the high level, all the heuristics performed equally well.

The effect of temperature on the hardseed content of some annual legumes grown on the northern slopes of New South Wales

1990 ◽  
Vol 41 (5) ◽  
pp. 941 ◽  
Author(s):  
GM Lodge ◽  
RD Murison ◽  
EW Heap
Keyword(s):  
Seed Set ◽  
New South ◽  
Trifolium Subterraneum ◽  
Summer Rainfall ◽  
Effect Of Temperature ◽  
South Wales ◽  
Low Levels ◽  
Fluctuating Temperatures ◽  
Over Time ◽  
Better Than

Two laboratory experiments were conducted to assess the effects of constant and fluctuating temperatures on the hardseed content of a range of legume species. In the first experiment the effects of constant (10/10,25/25,40/40�C) and fluctuating temperatures (40/10,40/25�C) on the rate of breakdown of the hardseed of 15 legumes was examined over a 12-month period. The second experiment investigated the hardseed level of seven of these legumes stored at temperatures of 25/25,40/25,60/25�C over 11 months. A method of analysing these data is presented which describes the hardseed profile over time and allows the rates of change to be compared. For seed collected in a summer rainfall environment fluctuating temperatures of 40/10�C significantly reduced the hardseed level of Medicago aculeata Willd. and M. scutellata (L.) Mill, cv. Sava, Trifolium subterraneum ssp. subterraneum Katzn. et Morley cv. Woogenellup and T. subterraneum ssp brachycalycinum Katzn. Et Morley cv. Clare. A 40/25�C regime reduced the hardseededness of M. minima (L.) Bart, M, aculeata, M. truncatula Gaertn. cv. Sephi, T. subterraneum ssp, subterraneum Katzn. et Morley cvv. Nungarin and Woogenellup and cv. Clare. At 60/25�C the hardseed level of all legumes declined over time. Further at 60/25�C hardseed contents declined at a significantly faster rate than for those at 40/25�C. Field observations of the number of seedlings emerging in the summer after seed set followed a similar pattern to that expected from the laboratory studies. From these studies it is proposed that, provided their seed set is adequate, cultivars with comparatively low levels of hardseed may perform better than expected when grown in a summer rainfall environment, particularly when they are either grown in association with native grasses or have a high proportion of buried burrs. Under these conditions temperatures of around 40/25�C could be expected.

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