An Exact Approach to Early/Tardy Scheduling with Release Dates

In this paper we consider the single machine earliness/tardiness scheduling problem with di?erent release dates and no unforced idle time. The problem is decomposed into a weighted earliness subproblem and a weighted tardiness subproblem. Lower bounding procedures are proposed for each of these subproblems, and the lower bound for the original problem is then simply the sum of the lower bounds for the two subproblems. The lower bounds and several versions of a branch-and-bound algorithm are then tested on a set of randomly generated problems, and instances with up to 30 jobs are solved to optimality. To the best of our knowledge, this is the first exact approach for the early/tardy scheduling problem with release dates and no unforced idle time.scheduling, early/tardy, release dates, lower bounds, branch-and-bound

Improved Lower Bounds for the Early/Tardy Scheduling Problem with No Idle Time

In this paper we consider the single machine earliness/tardiness scheduling problem with no idle time. Two of the lower bounds previously developed for this problem are based on lagrangean relaxation and the multiplier adjustment method, and require an initial sequence. We investigate the sensitivity of the lower bounds to the initial sequence, and experiment with di?erent dispatch rules and some dominance conditions. The computational results show that it is possible to obtain improved lower bounds by using a better initial sequence. The lower bounds are also incorporated in a branch-and-bound algorithm, and the computational tests show that one of the new lower bounds has the best performance for larger instances.scheduling, early/tardy, lower bound

Heuristics for the Early/Tardy Scheduling Problem with Release Dates

In this paper we consider the single machine earliness/tardiness scheduling problem with di?erent release dates and no unforced idle time. We analyse the performance of several dispatch rules, a greedy procedure and a decision theory local search heuristic. The dispatch rules use a lookahead parameter whose value must be specified. We perform some experiments to determine an appropriate value for this parameter. The use of dominance rules to improve the solutions obtained by these heuristics is also considered. The computational results show that the use of the dominance rules can indeed improve the solution quality with little additional computational e?ort. To the best of our knowledge, this is the first analysis of heuristic performance for the early/tardy scheduling problem with release dates and no unforced idle time.scheduling, early/tardy, release dates, heuristics

Improved Heuristics for the Early/Tardy Scheduling Problem with No Idle Time

In this paper we consider the single machine earliness/tardiness scheduling problem with no idle time. We present two new heuristics, a dispatch rule and a greedy procedure, and also consider the best of the existing dispatch rules. Both dispatch rules use a lookahead parameter that had previously been set at a fixed value. We develop functions that map some instance statistics into appropriate values for that parameter. We also consider the use of dominance rules to improve the solutions obtained by the heuristics. The computational results show that the function-based versions of the heuristics outperform their fixed value counterparts and that the use of the dominance rules can indeed improve solution quality with little additional computational effort.scheduling, early/tardy, heuristics, dispatch rules, dominance rules

Beam search algorithms for the early/tardy scheduling problem with release dates

In this paper we consider the single machine earliness/tardiness scheduling problem with di?erent release dates and no unforced idle time. We present several heuristic algorithms based on the beam search technique. These algorithms include classical beam search procedures, with both priority and total cost evaluation functions, as well as the filtered and recovering variants. Both priority evaluation functions and problem-specific properties were considered for the filtering step used in the filtered and recovering beam search heuristics. Extensive preliminary tests were performed to determine appropriate values for the parameters used by each algorithm. The computational results show that the recovering beam search algorithms outperform their filtered counterparts in both solution quality and computational requirements, while the priority-based filtering procedure proves superior to the rules-based alternative. The beam search procedure with a total cost evaluation function provides very good results, but is computationally expensive and can therefore only be applied to small or medium size instances. The recovering algorithm is quite close in solution quality and is significantly faster, so it can be used to solve even large instances.scheduling, early/tardy, beam search, heuristics

Being an effective leader: relationship between philosophy, practice and leadership indicators

info:eu-repo/semantics/publishedVersio

Spinach production in cocopeat: effects of soil block number and the number of emitters per styrofoam box on plant growth, nitrate concentration, and antioxidant activity

Currently, the interest in using cocopeat or coir dust alone as a growing medium to produce leafy vegetables has increased. This research aimed to evaluate the effects of soil block number and of the number of emitters per styrofoam box on plant growth, nitrate (NO3-) concentration, and antioxidant activity in spinach (Spinacia oleracea L. 'Manatee') cultivated in cocopeat. The experiment was carried out with four treatments, 8 and 14 soil blocks (160 and 280 plants m‑2) and 4 and 8 emitters per styrofoam box. The crop was irrigated and fertigated daily with a complete nutrient solution. The yield (kg m‑2) was increased significantly with soil block number and with the number of the emitters by styrofoam box, reaching 5.4 kg m‑2 in the treatment with 14 soil blocks (280 plants m‑2) and 8 emitters. Soil block number had no effect on shoot dry weight plant‑1, leaf-blade and petiole nitrate concentration and total phenols content. The increase in the number of emitters per styrofoam box decreased leaf-blade total phenol sand leaf-blade antioxidant activity. Ferric-reducing antioxidant activity (FRAP) values in the leaf-blade treatments with four emitters ranged from 7.3 to 9.7 mg eq. trolox g‑1 FW. The leaf-blade phenols content and FRAP values were ≈8 and 9 times higher than in the petioles, respectively. These results indicate that cocopeat is a very suitable growing medium for spinach production

One-dimensional numerical modelling of turbidity currents: hydrodynamics and deposition

River morphodynamics and sediment transportSedimentation in reservoir

Effects of Municipal Solid Waste Compost Supplemented with Inorganic Nitrogen on Physicochemical Soil Characteristics, Plant Growth, Nitrate Content, and Antioxidant Activity in Spinach.

In this study, we evaluated the effects of municipal solid waste compost supplemented with inorganic N on the physicochemical properties of soil, plant growth, nitrate concentration, and antioxidant activity in spinach. Experiments were carried out in neutral and acidic soils that were low in organic matter. A fertilized soil was used as a control, while four compost treatments—two compost rates of 35 and 70 t ha−1, supplemented or not with inorganic N (92 kg N ha−1 as Ca (NO3)2)—were applied by fertigation. The addition of compost increased the soil organic matter content and pH in both soils. The compost supplementation with N greatly increased the shoot dry weight and spinach fresh yield by nearly 109%. With the highest compost rate and 43% N applied, the yield increased in both soils, similar to results obtained in fertilized soil (3.8 kg m−2). The combined application of compost and N could replace inorganic P and K fertilization to a significant extent. The compost application at both rates and in both soils considerably decreased shoot Mn concentrations