Sharif Digital Repository

The sustainable retrofit options may significantly improve the energy consumption and the environmental impacts of the existing buildings. This paper presents a multi objective optimization framework to reach the minimum economic costs and Global Warming Potential (GWP) impact of existing buildings. New energy-efficient technologies for the supply side of the energy system are considered which may minimize life cycle environmental impacts of buildings. Two educational buildings in the campus of Sharif University of Technology are studied. The results show that utilizing reciprocating engine and exhaust-fired absorption chiller reduce the GWP to 133 tons (17.79% of reduction) and 190 tones... 

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... 

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... 

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... 

In this paper, we focus on a cognitive network scenario, comprised of a multi-hop IEEE 802.11-based WLAN overlaid on a cellular network. In this scenario, the wireless nodes in a WLAN, i.e., cognitive nodes, use the downlink frequency channels of the cellular network opportunistically, such that at each packet transmission all idle channels have been exploited. In order to evaluate the capability of the considered cognitive network scenario, we propose an open queueing network model such that different packet transmission phases are mapped onto different queueing nodes. We also map different types of collisions, i.e., collision on control signals as well as collision on data transmission due... 

Low-carbon steel sheets are severely plastic deformed to strains of up to ≈3.48 and subsequently heat treated by conventional annealing followed by water-quenching. Four temperatures are chosen for the annealing below and over the Ac1 and Ac3 transformation lines. The effects of post-deformation heat treatment are investigated by evaluating the microstructure and mechanical properties, including strength, ductility, work hardening capability, and hardness. A maximum increase of 86% in the strength is obtained through intercritical annealing and quenching of the samples subjected to strain of 1.16. It is interesting that both the elongation and ultimate tensile strength values are higher... 

Deteriorated urban areas in large cities have poor living standards, are inaccessible and small-sized, and have unstable building structures. Earthquake hazards may turn such situations into human disasters. In most cases, neither the governments nor the owners of these properties have enough budgets for renovating them. The purpose of this paper is to take advantage of Transit Oriented Development concepts to simultaneously solve two major urban area problems: (a) renovation of deteriorated urban areas and prevention of urban sprawl, and (b) design of transit network and promotion of transit-oriented development to reduce traffic congestion, pollution, and other unwanted outcomes of the... 

Deteriorated land-uses constitute vast portions of the metropolitan areas, being small lots of land, hardly accessible, structurally unstable, and extremely vulnerable to moderate earthquakes. We present the results of a stated preference survey done to support the viability of administering a novel tri-lateral Public–Private Partnership of Build-Operate-Transfer type proposal of Government (G)-Residents (R)-Private Sector Investors (P). In this proposal, the (low income) R in a zone trade their lands for an equivalent value of safe housing built by P next to a newly constructed Bus Rapid Transit line built by G in the same zone, thus a Transit-Oriented Development. P, in return, receives...