Sharif Digital Repository

A disaster's response and recovery phases can be characterized by the breadth of activities, complex interrelationships of multiple involved agencies, and uncertain outcomes. Proper performance and collaboration of responsible agencies can mitigate disaster-induced losses. Past studies have not holistically investigated the role of responsible agencies’ operation and cooperation in post-disaster community recovery. This study proposes a hybrid framework that facilitates the probabilistic modeling of responsible agencies' post-disaster performance and coordination. An Agent-based Modeling (ABM) sub-model simulates the operations and interactions of responsible agencies. A System Dynamics (SD)... 

In the absence of effective and adequate vaccines, healthcare decision-makers must rely on non-pharmaceutical interventions (NPIs), such as lockdown, testing, hospital capacity building, and increasing the number of medical staff to control the outbreak of an infectious disease like COVID-19. This manuscript presents a System Dynamics (SD) model to analyze the healthcare system performance under various NPIs during a pandemic. The proposed model, which extends the commonly-used Susceptible-Exposed-Infectious-Recovered (SEIR) model, comprises four sub-models: outbreak, hospital performance, medicine supply, and staff functionality. These sub-models work in harmony to stimulate the impact of... 

Shared hosting is a kind of web hosting in which multiple websites reside on one webserver. It is cost-effective and makes the administration easier for websites' owners. However, shared hosting has some performance and security issues. In default shared hosting configuration, all websites' scripts are executed under the webserver's user account regardless of their owners. Therefore, a website is able to access other websites' resources. This security problem arises from lack of proper isolation between different websites hosted on the same webserver. In this survey, we have examined different methods for handling mentioned security issue. Also we evaluated the performance of mentioned... 

Due to their agile manoeuvrability and simplicity of construction, quadrotor are employed in a variety of applications. Most of their expenses are due to complex control systems, since, to reduce these expenses, low cost control methods which are based on linear models should be used to achieve an autonomous flight. First, the process of accurate dynamic modeling of a sample quad rotor which is simulated by MATLAB SIMULINK is presented. Then, a frequency sweep input stimulates the virtual model in order to identify a linear model based on frequency response analysis. Consequently, the desired linear model is obtained in both hover and yaw mode of motion. However, pitch and roll mode were too... 

With the outbreak of the coronavirus in countries around the world, governments have decided to impose restrictions and social distancing. Closures of businesses, and hence changes in supply and demand patterns during this period, have deepened concerns among policy makers. In this article, we investigate the change in primary energy consumption in the 20 European countries that have the highest GDP. To this end, 10 different shock scenarios and its limitations are considered. By implementing these shocks into input-output modelling, changes in primary energy consumption are calculated. The results show that according to the best scenario (rapid and complete economy restoration), Russia with... 

During recent years, extensive studies have been conducted around the world documenting liquefaction induced lateral spreading and its effects on deep foundations. This study is aimed to numerically model a shaking table experiment, to investigate the effect of lateral spreading on piles and also to assess the capability of an advanced critical state two-surface plasticity model in predicting soil and pile responses to lateral spreading. Changes in permeability of the soil layers during the shaking are also accounted for using the software's built-in programming language, FISH. Numerical results showed that the onset of liquefaction occurs after just a few cycles from the beginning of the... 

Fusion of high spectral but low spatial resolution multispectral and low spectral but high spatial resolution panchromatic satellite images is a very useful technique in various remote sensing applications, such as change detection. Recently, some studies showed that wavelet-based image fusion methods provide high quality spectral content of the fused image. However, most of wavelet-based methods have a spatial resolution of the fused result less than the Brovey, IHS, and PCA fusion methods. This is mainly because real wavelet transform cannot efficiently represent the singularity of linear/curved contents. In this paper, we introduce a new method based on the contourlet transform which... 

The purpose of the present study is to develop the neutron diffusion solver and neutron noise simulator based on the Boundary Element Method (BEM). The 2-D, 2-G neutron/adjoint diffusion equation and corresponding neutron/adjoint noise equation were solved using the mentioned method. The developed neutron static and noise simulator based on the finite element method gives accurate results when the more number of the elements is used. The motivation of the present research is to use the boundary element method to reduce the computational cost. The boundary element method attempts to use the given boundary conditions to fit boundary values into the integral equation, rather than values... 

Electrodeposition of the Co-Ni/Cu multilayer films was carried out in sulfate solution. Cyclic voltammetry and current transient techniques were utilized to characterize the multilayer system and to obtain the nucleation and growth mechanism. The cyclic voltammograms clearly showed that electrodeposition of cobalt-nickel alloy layer was controlled by a kinetic process, where copper ions were reduced under diffusion-controlled mechanism. In addition, the current transients revealed that nucleation mechanism was instantaneous with a typical three-dimensional growth process. The microstructure of the Co-Ni/Cu films was also changed with overpotential. In this system, the growth of multilayer... 

This paper presents an optimal algorithm based on Branch and Bound approach for determining lot sizes for purchased component in Material Requirement Planning (MRP) environments with deterministic time-phased demand and constant ordering cost with zero lead time. Backlog is not permitted and the unit purchasing price depends on the quantity of an order and resale of the excess is possible at the ordering time. We assume an all-units discount system with single price break point. Based on proven properties of an optimal order policy, a tree search procedure is designed to construct the sequences of orders and resales amount in optimal order policy. Some useful fathom rules have been proven to... 

This paper presents an optimal algorithm based on Branch and Bound approach for determining lot sizes for purchased component in Material Requirement Planning (MRP) environments with deterministic dynamic demand pattern and constant ordering cost with zero lead time, where all units discounts are available from vendors and shortage is not allowed. Based on the properties of an optimal order policy proven in the literature, a tree search procedure is designed to construct sequences of orders in the optimal policy. Some useful fathom rules have been proven to make the algorithm very efficient. Copyright©(2008) by Computers & Industrial Engineering  

Traditionally, flying and handling quality evaluation of an aircraft in various flight phases is aimed at pilot workload assessment to guarantee a successful mission. Subsequently, Different levels of acceptability are defined for the aircraft based on the additional work required by the pilot to achieve a desired performance level, feting scales are usually numerical, which pilots utilize as a mean to quantify their subjective opinion about an existing aircraft after hours of flying. Cornell aeronautical laboratory used their own scales in flying qualities research for many years and Cooper of NASA originated a ten-point numerical scale that was used more universally. When Harper of Cornell... 

We obtain an exact analytical expression for magnetoresistance using noncommutative geometry and quantum groups. We then show there is a deep relationship between magnetoresistance and the quantum group suq(2), from which we understand the quantum interpretation of the quantum corrections to the conductivity  

The treatment facility of Albourz Industrial City was established in 1999 at the southeast of Albourz Mountain with an area of 200,000 square meters. Currently, 40,000 cubic meters of industrial wastes are treated daily utilizing biological method of activated sludge up to the second phase without chlorination in this treatment facility. Then, the discharged wastes are directed toward the lower agricultural lands. The environmental status of the region was investigated by testing the impact of wastewater and agricultural products in four tries. In two tries, the levels of COD and BOD were higher than the environmental standards, but there was no trace of heavy metal contamination in any of... 

The authors consider the Multi-Skilled Project Scheduling Problem (MSPSP) as a version of the Multi-mode Resource-Constrained Project Scheduling Problem (MRCPSP), which extends the well-known NP-hard Resource-Constrained Project Scheduling Problem (RCPSP). In the MSPSP, it is made up of activities, which require specific skills to be done. Moreover, resources are staff members who master fixed skill(s). Thus, each resource requirement of an activity corresponds to the number of persons doing the corresponding skill that must be assigned to the activity during its whole processing time. The authors focus on taking into account the setup times when performing work, depending on the appointment... 

Rapidly exploring random trees (RRT) are sampling-based approaches being widely applied for path planning of mobile robots. Since the output of these algorithms usually is a stream of discrete lines involving discontinuity at the linking points, kinematic constraints restrict the robot's movements. Consequently, robots may not pass discrete points in the path correctly. Hence, the using CAGD (Computer-Aided Geometry Design) curves can run simultaneously alongside those algorithms or may run after that to make a smooth path and that's the way in which non-holonomic constraints can be considered perfect and robots can be droved autonomously across them about the collision detection method... 

We obtain an exact analytical expression for magnetoresistance using noncommutative geometry and quantum groups. Then we will show that there is a deep relationship between magnetoresistance and the quantum group su q(2), from which we understand the quantum interpretation of the quantum corrections to the conductivity. © 2003 Elsevier B.V. All rights reserved  

Rapidly exploring random trees (RRT) are sampling-based approaches being widely applied for path planning of mobile robots. Since the output of these algorithms usually is a stream of discrete lines involving discontinuity at the linking points, kinematic constraints restrict the robot's movements. Consequently, robots may not pass discrete points in the path correctly. Hence, the using CAGD (Computer-Aided Geometry Design) curves can run simultaneously alongside those algorithms or may run after that to make a smooth path and that's the way in which non-holonomic constraints can be considered perfect and robots can be droved autonomously across them about the collision detection method... 

In this research, an extended finite element model has been investigated. Investigation of opening and closure stress always has been one of the difficult parameters to analysis of results; therefore, the utilization of finite element methods would be a good and logical alternative for this purpose. In addition, linear elastic fracture criteria are used for validation of numerical results from the simulation. In this work, a detailed analysis of the influence of different parameters in the results of a specific specimen with a semi-elliptical tooling groove in terms of closure and opening stress is presented, and the impact of optimum element size in fracture characteristic in various load...