In engineering designs, structural analysis is generally performed assuming a rigid base. While introducing the effect of structural substrate flexibility on the response and dynamic properties of structures is important. Introducing different solutions to reduce the response of the structure against dynamic forces is another important issue in engineering designs. In this paper, the passive Pall friction damper system has been used for this purpose. In the researches that have been done so far, various optimization methods have been used for the optimal design of friction dampers, but in most of these methods, the effect of soil-structure interaction has not been considered for friction dampers, while in earthquake soil-structure interactions are important. One of the main objectives of this study is to investigate the effect of soil-structure interaction on the optimization of friction dampers. The actual forces and displacements of a structure due to free-surface seismic movements can be determined by considering the effects of soil-structure interaction. In this regard, in this paper, two-dimensional frames of 4, 8, and 12 floors equipped with dampers were analyzed in nonlinear structural analysis software under seven accelerometers using the nonlinear time history method once, considering the effect of soil-structure interaction and introducing 3 Different lateral loading patterns and again without this effect. The results show that considering this issue in terms of cumulative triangular slip load pattern has increased the loss of earthquake input energy. Also, depending on the type of load pattern, the applied record and the height of the structure, a decrease has been observed, which is mentioned in the results section.

The main purpose of this research is an experimental study of a type of rotational-friction dampers with two slip loads and numerical study of the behavior of reinforced concrete frames with this type of dampers under cyclic loading. For this purpose, first, the mechanism of action of the proposed damper will be explained. In the next step, two specimens of rotational-friction dampers with two different slip loads are investigated in the laboratory. Then, using the Opensees software, a behavioral model is proposed for it and validated using experimental results. In the final step, one story-one bay reinforced concrete frame in four states, (1) without damper, (2) with rotational-friction damper with one slip load (RFD), (3) with the rotationalfriction damper with two slip load type S01 and (4) rotational-friction damper with two slip load type S02, under cyclic loading will be analyzed and the results will be investigated. The results of experimental studies show that the effective stiffness in the final cycle for specimens S01 and S02 were 109 and 128 tons per meter, respectively, while their effective damping in the final cycle is about 0. 48, which indicates the appropriate ability of experimental specimens to absorb earthquake energy and reduce structural damage. Also, the results of numerical studies of reinforced concrete frame show that concrete frame with S01 damper has better seismic performance because its ultimate strength is 15% and its dissipated energy in the final cycle is 164% more than the ultimate strength and energy dissipation of the final cycle of the frame without damper.

Statement of Problem: Zirconia has been introduced as an appropriate structure for fabricating metal free copings. A major advantage of such restorations is esthetic concerns; however, due to its high strength, zirconia can also be used in posterior areas. One of the recent methods of making these restorations is CAD/CAM machines.Purpose: This study aimed to evaluate the fracture resistance of zirconia copings fabricated by two methods, CAD/CAM and slip casting.Materials and Method: 32 brass dies were fabricated for this study and divided into two groups of 16 dies each. Zirconia copings were made by CAD/CAM machine for one group and by slip casting method for the other. The copings were cemented to dies by a resin-modified glass ionomer (GC plus). A hardened steel ball with a diameter of 5 mm was used to apply the load to the copings in the long axis of the dies at a crosshead speed of 0.5 mm/min. Then the amount of force needed to fracture each coping was recorded. Independent Sample T-test was used to compare the two groups.Results: The average of fracture resistance for the CAD/CAM group was 1411±424 N and for the slip cast group it was 1542±412 N, having no significant difference (p>0.05).Conclusion: Zirconia copings made by CAD/CAM and slip casting methods have no significant difference in fracture resistance.

Background and Aim: It is believed that a period of healing, approximately 3-4 months for mandible and 4-6 months for maxilla, are required to ensure osseointegration. Recently, a new method called Immediate loading of implants have been proposed. This method provides improved stability of the implant by the immediate support of an iterim prosthesis. The aim of this study was to evaluate the success rate of the Immediate loading single OPILS dental implants.Materials and Methods: Thirty-nine patients, including 26 females and 13 males, at the minimum age of 18 and maximum age of 54 years old, received 48 OPILS dental implants. In this prospective study, all samples were non-smoking, without any systemic disease or psychological problem. In all cases, and acrylic prefabricated crown was placed immediately after implant surgery. The definitive metal-ceramic crown was placed 2.5 months later in mandible and 5.5 months later in maxillae. Lack of pain, pus, implant immobility and less than 1mm bone loss were criteria of success.Results: The oral hygiene of females were better than males, 26 women had plaque index (0) and 11 of them had plaque index (1) where as out of 13 male subjects, 4 had plaque index (0), 6 had plaque index (2) and (3) had plaque index (3). The mean vertical bone loss, on mesial and distal parts, were less than 1mm, with the min. of 0 and max. of 0.4mm and the average of 0.2mm. All implants pass the defined criteria of success.Conclusion: On the basis of this short-term study, in single tooth cases, OPILS implants of Neo-Dent system can be loaded immediately.

One of the most significant operational aspects of vehicles is their safety in critical braking maneuvers. Proper braking performance occurs when the stopping distance is minimized while the vehicle’s steerability is maintained. To meet these objectives, the tire slip ratio should be regulated at its optimum value. In this study, a control system is designed for simultaneously controlling the brake torque of the front and rear wheels using the nonlinear prediction-based control method. In the control design process, the pitch dynamics have been considered which plays an important role in braking maneuvers. Moreover, the instantaneous optimum wheel slip is determined via an artificial neural network (ANN) to improve the performance of the system and achieve the maximum possible brake deceleration. The performance of the designed control system is investigated through conducted simulations in the CarSim and Matlab/Simulink software environments. The obtained results confirm the enhancement in the braking performance along with a considerable reduction in the stopping distance.

One of the most significant operational aspects of vehicles is their safety in critical braking maneuvers. Proper braking performance occurs when the stopping distance is minimized while the vehicle’s steerability is maintained. To meet these objectives, the tire slip ratio should be regulated at its optimum value. In this study, a control system is designed for simultaneously controlling the brake torque of the front and rear wheels using the nonlinear prediction-based control method. In the control design process, the pitch dynamics have been considered which plays an important role in braking maneuvers. Moreover, the instantaneous optimum wheel slip is determined via an artificial neural network (ANN) to improve the performance of the system and achieve the maximum possible brake deceleration. The performance of the designed control system is investigated through conducted simulations in the CarSim and Matlab/Simulink software environments. The obtained results confirm the enhancement in the braking performance along with a considerable reduction in the stopping distance.

Introduction: Kitchen workers are in danger of slip accident because of slippery surfaces created by contaminants like grease, water and food material. The aim of this study was to investigate the prevalence and slip risk assessment in cooking sites of Shiraz.Material and Method: This cross-sectional study was conducted on 322 cases from commercial kitchens in traditional and fast food restaurants, located in Shiraz, Iran, who was willing to cooperate in the project. (The total number of restaurants was 1303 cases. And simple random sampling method was used). The risk of slips was assessed using Slip Assessment Tool (SAT), developed by Health and Safety Executive (HSE). Prevalence of slip accidents was investigated using a questionnaire among kitchens staffs. Roughness coefficient was measured using Roughness Meter TQC-SP1560. Data analysis was performed using SPSS-22 software.Result: The level of slip risk was at moderate level in 47% of studied kitchens and others had low level of slip risk. Slip risk level in kitchens of traditional restaurants was significantly higher than fast foods. The average value of the measured surface roughness was obtained 4191.39 mm. The highest and lowest, respectively 4458.2 and 3977.3 mm were reported. The prevalence of slip accidents was reported to be 50.3%. Most of slip accidents was occurred in the kitchens, and when the floor was wet with water or contaminated with food products.Conclusion: The results of this study showed that due to differences in the type, method and time of food services and also workload of personnel, slip risk in kitchens of traditional restaurants was higher than fast foods. Approximately, in 50% of studied kitchens, the level of slip risk was assessed as moderate. Some basic interventions in spillage control and cleaning procedures, floor surface characteristics and using slip-resistant shoes are required to reduce the risk of slip in kitchens.

One of the obvious reasons for most disorders in network service provisioning is network path congestion. Congestion avoidance in today's networks is too costly and sometimes impossible. With the introduction of SDN, centralizing the equipment's control plane has become possible. This paper presents an enhanced method named ESV-DBRA to avoid congestion in multi-tenant SDN networks. At first, ESV-DBRA monitors the traffic load and delay of all network paths for each tenant individually. Then, by merging the parameters obtained from the monitoring, the Service Level Agreements (SLA), and a novel proposed cost function, it calculates the cost of the network paths per tenant. As a result, traffic for each tenant is routed through the path/paths at the lowest possible cost from the tenant's perspective. Next, the bandwidth quotas will be calculated and assigned to the tenants over their optimal routes. Afterward, whenever congestion is likely to occur in a path, ESV-DBRA automatically changes the route or bandwidth of the tenants' traffic related to this path to avoid congestion. Related algorithms are also proposed.Eventually, simulations show that the proposed method effectively increases bandwidth utilization by 10.76%.