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In this paper, the behavior of the double pendulums has been studied by considering the effect of initial conditions (angular displacement of the outer pendulum for four cases 12, 30, 90, and 150 degrees) and the influence of system geometry (increasing rod length and mass of the second pendulum), also. After extracting motion equations using the Lagrangian method, in order to deal with the frequency spectrum, traces of bobs, and understanding the system behavior for every case, the Fast Fourier Transform (FFT) technique and Poincare sections have been applied. The obtained results show that the consequence of the rising angular displacement the outer pendulum is to increase the energy level of the system and the change of its behavior from quasi-periodic for angular displacement is less than 90 degrees to chaotic when it is 150 degrees. Therefore, the energy level, in this case, has increased more than twice compared to the first. In addition, it seems a quasi-periodic behavior is forming at the heart of chaotic behavior. On the other hand, the results indicate a very significant effect of geometrics on a system's behavior. According to the calculations, the consequence of increasing the length of the rod of the second pendulum has only led to a different behavior from its similar case (case number 3) completely. however, their energy level is the same. Increasing the mass of the outer by twice not only to lead decrease energy level of the system by 330J but also has shown chaotic behavior (in comparison to the case3).

In the single-mode resource-constrained project scheduling problem, it is assumed that each activity has a specified known execution time and resource consumption can be done only in one way. In practice, there are many cases in which the make span can be reduced by providing additional resources activities. In this case, each activity can be done in one of the procedures, which is called the multi-mode resource-constrained project scheduling. In this paper, the problem includes determination of the basic schedule for the project activities which may be done in several models and the precedence relations are met, While the project make-span, cost and resource fluctuations are minimal. In this research project scheduling problem network will model using ED simulation software and the results of the simulation and a meta-heuristic algorithm has been compared. Finally, management strategies to optimize the scheduling, i.e such minimize total time, cost and resource leveling, will be offered. [ABSTRACT FROM AUTHOR]

Microgrid can operate in both grid-connected and islanded modes. Islanding can be scheduled or unscheduled. In the event of unscheduled islanding, the microgrid should be able to maintain its sustainability. Therefore, it is necessary to determine and supply the amount of required spinning reserve for stable islanding. In this paper, a two-stage strategy for optimal scheduling of the microgrid is proposed while uncertainties of renewable generations and demand are considered. In the first stage, co-optimization of power and reserve is carried out with the presence of distributed generations and batteries. Therefore, in the second stage, the demand is also used as reserve to provide required reserve for stable islanding. In order to determine the optimal amount of reserve of demand, a novel objective function is proposed. The objective function minimizes the sum of the standby reserve cost, expected cost of called reserve, and expected cost of emergency curtailment. One of the salient features of the proposed model is its modularity. That is, it can be added easily to any scheduling model in which the demand is not considered as reserve. Mathematical analysis and numerical simulations show the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Introduction: The queue is one of the most complex social systems in which human lives are inevitably ‎associated with the activities of organizations. Due to the characteristics of healthcare ‎organizations and the critical role that planning plays in such organizations, research in this regard ‎can be of great help. This paper was an attempt to demonstrate the role and use of the branches ‎of the operations research discipline in healthcare centers. Methods: The current research was a cross-sectional study conducted on‏ ‏‎2614‎‏ ‏patients referred to the ‎paraclinic ward of Hafez Hospital, Shiraz, Iran. In order to collect data, the patient code, time of arrival, work start time, serving start and end time were recorded with the help of staff and two assistants at the time of arrival of the patients. Then, modeling and optimization of patient flow were conducted using queues and simulation techniques. The data was analyzed using SPSS software and Input Analyzer ‎Software and the system was simulated using Arena software. Results: The results showed that 30% of the patients no longer wished to be referred back to the center. ‎The findings also revealed that there was a significant difference between the standard waiting ‎time and the time spent in the hospital to recive a service. Among the 6 different scenarios, the ‎mixed scenario reduced waiting time of the first service for‏ ‏sonography patients to 75.04 minutes ‎and for radiology patients to 65.573 minutes. Conclusion: The results showed that the suggested model, in comparison to the current model of health ‎centers, can improve the‏ ‏quality of services and reduce the duration of time patients must wait ‎until receiving the first service‏.

Background and Aims: Improving dental implantation conditions in order to reduce the failure is always desirable for researchers. The aim of this study was to compare two different materials of dental implants from the viewpoint of biomechanical effect after placement and loading in the mandible. Materials and Methods: A 3D model of mandible was designed in the MIMICS 10.01 software. Then, by using the obtained model, the end part of the mandible was designed in CATIA V5 software and a drilling operation was performed on the cortical bone of mandible by finite element analysis simulation method in DEFORM-3D V6.1 software. Thereafter, the 3D model of created hole was extract from the drilled site and an ITI dental implant model designed in the CATIA V5 software, was placed in the hole. The space remained between the implant and cavity was considered as a newly-formed cortical bone in drilled site after 6 weeks of dental implant placement and the mechanical properties of newly-formed bone were entered to DEFORM-3D V6.1 software. Then, a load was applied on the top surfaces of two dental implant models with the materials titanium and zirconium-2.5% niobium. Results: The emerged volume changes in newly formed cortical bone around Ti and Zr-2.5 Nb dental implants were measured 0.238 and 0.242 percent, respectively. Furthermore, micro-motion of Ti and Zr-2.5 Nb dental implants were measured 0.00514 and 0.00538 mm, respectively. Conclusion: The results of this study showed that Ti dental implant created better conditions than Zr-2.5 Nb dental implant in the mandible. [ABSTRACT FROM AUTHOR]