Sharif Digital Repository

A special type of shell structure - a concrete shallow funicular shell of circular plan - is considered in this paper. Funicular shells carry their dead weight only by in-plane compression forces. Numerical analysis of funicular shells was performed using the non-linear finite-element method, considering both geometric and material non-linearities. A circular-plan concrete funicular shell unit was also constructed and its ultimate central concentrated load is determined. The ultimate load of the shell unit predicted by the numerical model was very close to the experimentally determined ultimate load, thus confirming the validity of the numerical model. The numerical results revealed the... 

As the semiconductor industry advances to the deep sub-micron and nano technology points, the on-chip components are more prone to the defects during manufacturing and faults during system operation. Consequently, fault tolerant techniques are essential to improve the yield of modern complex chips. We propose a fault-tolerant routing algorithm that keeps the negative effect of faulty components on the NoC power and performance as low as possible. Targeting intermittent faults, we achieve fault tolerance by employing a simple and fast mechanism composed of two processes: NoC monitoring and route adaption. Experimental results show the effectiveness of the proposed technique, in that it offers... 

This paper considers a realistic multi-service system design problem in which each service type is a stochastic sequence of services provided by different units of facilities where each facility is modeled as a set of open Jackson queueing networks. The problem is first formulated as a mixed-integer nonlinear programming model, which is further simplified to a model with a smaller number of constraints. Three exact solution methods are applied to solve the amended model. The first one is a cutting-plane method, which is based on a piecewise-linear approximation. The second is based on a mixed-integer linear programming formulation, which is enhanced by valid inequalities. The third is to use... 

The concrete compressive strength is essential for the design and durability of concrete infrastructure. Silica fume (SF), as a cementitious material, has been shown to improve the durability and mechanical properties of concrete. This study aims to predict the compressive strength of concrete containing SF by dual-objective optimization to determine the best balance between accurate prediction and model simplicity. A comprehensive dataset of 2995 concrete samples containing SF was collected from 36 peer-reviewed studies ranging from 5% to 30% by cement weight. Input variables included curing time, SF content, water-to-cement ratio, aggregates, superplasticizer levels, and slump... 

One of the underlying factors in the conservation and development of urban green spaces is the available water resources use for green areas in each region. The primary purpose of this study is to introduce the integration of a proper simulation method for runoff along with AHP-PROMETHEE decision-making method for water resources management in urban basins. The application of this approach was investigated in the city Buin Zahra of Qazvin Province of Iran. In the first step by using the analytic hierarchy process (AHP), the available water resources in the case study were weighted. In the second step, the water resources of the municipal and residential wells and water collected by... 

In this paper, a method for overtaking stationary and moving obstacles will be introduced. The method consists of designing a desired trajectory for lateral motion of the vehicle and then using a lateral motion controller for tracking this desired trajectory. The desired trajectory is a sigmoid exponential function of relative distance between the vehicle and the obstacle and guarantees overtaking the obstacle, if tracked exactly, despite of lateral and longitudinal motions of the obstacle. Lateral acceleration of the vehicle should not exceed safety limits during tracking desired trajectory. This matter has been used as a decision criterion for determining feasible and unfeasible desired... 

One of the most important capabilities expected from an autonomous vehicle is avoiding collision with obstacles in its path. For this purpose, autonomous vehicle must be able to perform an emergency maneuver as soon as the obstacle is detected. This paper presents a method for designing and performing an emergency maneuver in order to avoid collision with a fixed or moving obstacle in the path. A sinusoidal or exponential trajectory, which is a function of the relative distance between vehicle and obstacle, is designed as the desired trajectory for lateral motion of the vehicle. A sliding mode controller is designed in order to guarantee that the vehicle tracks that desired trajectory. The... 

One of the underlying factors in the conservation and development of urban green spaces is the available water resources use for green areas in each region. The primary purpose of this study is to introduce the integration of a proper simulation method for runoff along with AHP-PROMETHEE decision-making method for water resources management in urban basins. The application of this approach was investigated in the city Buin Zahra of Qazvin Province of Iran. In the first step by using the analytic hierarchy process (AHP), the available water resources in the case study were weighted. In the second step, the water resources of the municipal and residential wells and water collected by... 

Outpatient appointment scheduling problems have recently gained increasing attention. This paper provides a comprehensive review of recent analytical and numerical optimization studies that present decision-support tools for designing and planning outpatient appointment systems (OASs). A structure for organizing the recent literature according to various criteria is provided, including a framework that classifies decisions at the strategic, tactical, and operational levels. The OAS literature is evaluated from four perspectives: problem settings, environmental factors, modeling approaches, and solution methods. In addition, research gaps and areas of opportunity for future research are... 

Over-the-air computation (OAC) enables devices to compute functions over distributed data without sharing local raw data and provides an efficient, distributed, and privacy-preserving computation mechanism. This is achieved by leveraging channel mixing properties and decoding results from received signals. However, optimizing the effective wireless channel between devices and the base station is critical for effective OAC. Intelligent reflecting surfaces (IRS) can enhance transmission quality, but the resulting optimization problem becomes complex with increasing the number of devices. This paper examines clustering-based OAC using an IRS in which users share their data with the cluster head...