Sharif Digital Repository

This thesis proposes a new non-linear multi-objective Location-Inventory-Routing problem (LIRP( for perishable products considering multi trips for vehicles. Managing the expiration date of perishable products, speed of vehicles in the system, the frequency of using the vehicles and etc. bring complexity in LIRP in this problem.
First objective focuses on maximizing profits calculated by Incomes of selling goods with different worthwhile depend on their remained life time and costs of inventory and distribution as well as ordering. Minimizing CO_2 emmition as the environmental issue has been considered as the second objective. Third objective which is minimization of injury rate,... 

In 2009, a general equation of state (EOS-III) based on an effective near-neighbor pair interaction of an extended Lennard-Jones (3, 6, 12) type has been introduced as : , where is the compressibility factor, p and ρ stand for pressure and molar density , respectively, T is Temperature , and e, f and g are the temperature dependent coefficient of the equation of state . the Z_th and Z_in are the thermal and internal contributions of pressure in the compressibility factor, respectively. this equation of state gives a good description of all types of nano- and bulk –solid and bulk fluid at entire temperature and pressure ranges for which thee is experimental data. Investigation show that... 

The rise in carbon dioxide levels has led to the manifestation of numerous environmental challenges. Currently, the absorption and conversion of carbon dioxide into valuable fuel resources such as synthetic gas, methane, and ethylene are deemed crucial from both environmental and economic standpoints. Despite the presentation of photocatalysts such as titanium oxide and electrocatalysts such as copper, silver, and zinc, their efficiency in CO2 conversion is found to be insufficient. One potential solution to this problem is the utilization of photoelectrocatalytic CO2 recovery. In this study, the aim was to enhance the photoelectrocatalytic reduction of CO2 by designing and manufacturing... 

Ilam refinery has three synchronous generator units each with a capacity of 26.5 MVA and two six-phase LCI-fed synchronous compressors, each with a capacity of 8 MW. Generators of Ilam gas refinery have instability issue in case of island operation. With launching one generator unit and then connecting two compressors the instability problem and tripping of the generators appear. Given the importance of this issue, various tests and corresponding measurements in both electrical and mechanical aspects were carried out at the plant in on-grid and island operations to analyze the cause of instability phenomena. The mechanical part of tests analyses the frequency of oscillations and vibration in... 

In today’s modern world, there is an ever-increasing need for developing new ways to provide service in a health system in order to gain the satisfaction of the patients with economically effective methods. One of the challenges faced by a hospital is the allocation of the surgeries to the available surgeans. In this study, a mathematical model is proposed to schedule the operation rooms while considering the daily availability of the doctors, the expense of the operations, overtime hours, and post-operation care. The mathematical programming model is optimized as a stochastic model by using the approach of BIM.
An essential aspect of a hospital system design is the uncertainity of the... 

Geosteering is a process that is used in drilling oil and gas wells and its main goal is to reach hydrocarbon layers with high accuracy and optimal extraction from them. ROP is the distance drillied per unit of time, which has applications such as formation evaluation, boundary detection and maintaining the well path in geosteering. Gas ratio is another important parameter in this project which is strongly influenced by porosity, permeability and ROP. First, we give a brief introduction of various logs used in drilling like gamma-ray, density, neutron and sonic. Then in the literature review, we examine geosteering technologies such as automatic geosteering and machine learning. As we know,... 

Today, phased array antennas play important role in wireless communication systems. Utilizing optimum channel capacity, having better signal to noise ratio and, high data rate are the most important features of these systems.These systems are composed of several thousands of separated transceivers which provide possibility of directional electromagnetic radiation by changing the phase and the amplitude of the signal in each transceiver independently. So, the main components of such a system are amplifiers, phase shifters and, amplitude controllers. Also a high resolution phased array military radar system is another vital application of these systems at frequency band of 33-36 GHz.The... 

Increasing energy demand and at the same time, considering exhaustible fossil fuel resources has led to increase distributed generation for reducing energy loss and increasing efficiency of energy systems specially due to technical development on generation systems that meet environmental and energy policy concerns. One of the most important distributed energy technologies is Combined Heat and Power (CHP). CHP is small, high efficiency, low installation time and self-contained electric generation plant that can provide power for household applications, commercial or industrial facilities and hence its applications are overtly increasing. It can reduce power loss and enhance service... 

Sampling and recovery of a signal is one of the crucial issues in communication systems. In conventional methods, proper recovery is achieved by sampling the signal at the Nyquist rate, which is twice the signal bandwidth. There have been attempts on reducing the required sampling rate, all of which end in rates equal to a factor of the signal bandwidth. Assuming the sparse nature of the signal in hand, which is a reasonable assumption in many real world scenarios, the theory of Compressed Sensing suggests a sampling rate much less than the Nyquist rate. Designing suitable sensing matrices and efficient recovery of the signal from its samples are the two major challenges of Compressed... 

The development of technologies such as micro turbines and gas furnaces has been the major driving force towards integration of electricity and natural gas networks in the energy hubs (EH). Besides, the existing power grids are getting smarter by implementing the new generation of information technologies and communication systems. In smart grid, the electricity suppliers can modify the customers’ electrical load consumption by employing appropriate scheduling schemes such as DR (demand response) programs. In this thesis, I consider the S. E. Hubs (smartenergy hubs) framework, in which the customers can use EMS (energy management system) to access to the electricity and natural gas prices... 

High voltage power supplies have a wide range of applications, and due to their high cost, it is essential to monitor their condition to predict potential failures and prevent significant losses. The most common cause of power supply failure is the wear and tear of its components. However, these components can be replaced before they wear out completely to prevent the failure of the power supply and, consequently, avoid damaging the load. Estimating the lifetime of power supplies is crucial because it allows for scheduled maintenance and helps prevent significant problems in power supplies. By estimating the lifespan of a power supply, one can anticipate when it may fail, allowing for the... 

In many cases, oil and gas extraction from reservoirs due to damage and permeability reduction near wellbore is lower than optimum level and reduces the flow of oil into the well. In fact, formation damage is the collapse of natural condition of reservoirs, In addition to delaying production and increasing costs, it causes early desertification of wells. Well stimulation methods are used to solve this problem and increase production. One of the most effective ways to increase the production of wells is well acidizing. In this study, the acid performance of the fractured carbonate reservoirs has been investigated. In this type of reservoirs, due to the existence of high permeable paths of the... 

Parallel machine scheduling problems are the decision-making process of allocating limited resources to activities over time. These issues have attracted a lot of attention in the past decades based on their applications in the real world. It can be discussed about the application of parallel machine scheduling problems in computer processing, production lines and multi-stage systems as examples of areas where parallel machine is observed. Most of the research on parallel machine scheduling has focused on the optimization of a single criterion such as total or average task completion time, total completion time with different weights, sum of penalty or tardiness penalty, total number of... 

In the recent years, the role of combinatorics and graph theory have grown in the progress of computer sciences. For instance, the circulant graphs have applications in design of interconnection networks and the graphs with integer eigenvalues are applied in modelling quantum spin networks supporting the perfect state transfer. The circulant graphs with integer eigenvalues also found applications in molecular graph energy. In 2006, it was shown that an n-vertex circulant graph G has integer eigenvalues if G=Cay(Zn; T ) or G= Cay(Zn; T)∪Cay(Zn;U(Zn)), where T Z(Zn). The Cayley graph Cay(Zn;U(Zn)) is known as the unitary Cayley graph. Fuchs defined the unitary Cayely graph of a commutative...