A general overview of the scheduling’s literature of some researches shows that among various factors, the priority rules and also the structure of projects are two main factors that can be affected on the performance of Multidirectional scheduling schemes. In addition, a variation on the number of directors in scheduling schemes (e.g., single directional, bi-directional, and tri-directional scheduling scheme) produces different makespans. However, the question of when to move from the single direction to the Multidirectional scheduling schemes remained open. In this paper, based on analytical and also empirical results, we show that when availability and distributions of resource measures such as the number of peaks and number of overflows or the average amount of overflows are increased, higher directional scheduling schemes can be produced smaller makespans. Hence, in the light of these resource measures, the Multidirectional scheduling schemes can be reduced the dependency of the solution’s quality on the priority rules used.

The Resilient Packet Ring (RPR) architecture, known as the IEEE 802.17 standard, has received attention in the last year. The Priority Queue (PQ) algorithm is recommended as the scheduling scheme for RPR, which always gives priority to the transit buffer. Using this scheduling scheme in RPR, the high priority traffic, such as video packets waiting to access the ring at congested node in the transmit buffer, suffer large delays and unsteady delay jitters. In this, we propose new scheduling schemes base on Deficit Round-Robin (DRR) algorithm and compare it with the original schemes. To assess the efficiency of the system we simulate the network with 10 node attachments in the OPNET simulator and consider the efficiency of the new scheme. Using this scheme, the QoS of traffic transmission on the congested node can be significantly improved. Real time video traffic can benefit from such schemes.

scheduling problems have been considered by researchers from different aspects, and it has been widely addressed in the literature. Most scheduling problems, and almost all that arise in real-world applications, are NP-hard, therefore finding a proper and feasible solution, a solution that is performed in a reasonable time (polynomial time), is difficult. Approximation scheme, among different methods, is one approach that can overcome difficulties. Polynomial-time approximation and differential approximation schemes are categorized as approximation approaches based on comparing the proposed algorithm with optimum and worst-case solutions. As the first attempt, the paper investigates differential approximation schemes for the minimization of maximum delivery time. In this paper, the main methods and tools for proving the existence of an approximation scheme are presented. To do so, a differential approximation scheme is proposed by employing a polynomial-time approximation scheme (PTAS). The paper also reviews efficient approximation schemes on single machine problems with objective functions minimization of maximum delivery time, and minimizing the total weighted completion time. Also, in this paper, using the polynomial time approximation scheme (PTAS), a differential approximation scheme has been studied for the problem of minimizing the maximum delivery time of works, which has not been investigated so far.

scheduling problems have been considered by researchers from different aspects, and it has been widely addressed in the literature. Most scheduling problems, and almost all that arise in real-world applications, are NP-hard, therefore finding a proper and feasible solution, a solution that is performed in a reasonable time (polynomial time), is difficult. Approximation scheme, among different methods, is one approach that can overcome difficulties. Polynomial-time approximation and differential approximation schemes are categorized as approximation approaches based on comparing the proposed algorithm with optimum and worst-case solutions. As the first attempt, the paper investigates differential approximation schemes for the minimization of maximum delivery time. In this paper, the main methods and tools for proofing the existence of an approximation scheme are presented. To do so, a differential approximation scheme is proposed by employing a polynomial-time approximation scheme (PTAS). The paper also reviews efficient approximation schemes on single machine problems with objective functions minimization of maximum delivery time, and minimizing the total weighted completion time.

Multidirectional torsional hysteretic damper is a new type of damper that can be used to isolate and dissipate seismic effects on a structure. It can be designed to have a controllable post-elastic stiffness and exhibit high levels of damping as well as stable cyclic response. In this article, while offering a simplified numerical relationship for force-displacement response of the damper, the structure that is fitted with this innovative type of damper is optimized using the harmony search optimization procedure with discrete design variables. Numerical experiments show that the harmony search methodology can determine the damper parameters with high computational efficiency and outperform genetic algorithm and simulated annealing procedure in this regard.

Seismic evaluation of concrete dams due to some considerations is very important. The effects of fluid-structure-foundation interaction, nonlinear behavior of dam material due to crack, and earthquake loading are some of these considerations and should be considered in modeling and analysis of the system.The nonlinear seismic response of concrete gravity dams is presented when the effect of the dam-reservoir interaction is included using Lagrangian-Lagrangian approach of the finite element method. Nonlinear fracture mechanics, based on the smeared crack concepts, is used to study the cracking profile and response of the dam. In this study, a comparative study between the coaxial rotating crack model and orthogonal multi-fixed smeared crack models is carried out. Based on the presented formulation, Pine Flat concrete gravity dam is analyzed and its crest response and stresses within the dam body are founded. Bosak's time integration and corrected Newton-Raphson method are used for solving nonlinear dynamic equations.Results show that the two crack approaches have negligible Difference in terms of the number of cracked gauss points and the crack profile. Tensile principal stresses based on fixed crack concept are greater than those of the rotating crack concept, but for compressive principal stresses the results are vice versa. The differences are due to unloading-reloading path and shear retention factor, but crack propagating path remains the same. Displacements of dam crest in nonlinear cases are greater than those of linear ones and show the same result in two crack models. This phenomenon depended on internal damping of system in both linear and nonlinear cases. Permanent displacement of dam crest based on fixed crack concept is greater than that of the rotating crack concept, and this phenomenon depends on cracking intensity of dam body. Results show that the fixed crack concept have better convergence than that of the rotating crack concept and the number of iterations in the time steps are low.