Sharif Digital Repository

In this work, we use computational fluid dynamic simulation tools for investigation two dimensional of eel movement. Firstly, the numerical study of smooth particle hydrodynamics was applied for determination drag coefficient and lift coefficient of undulation movement eel body. The initial mesh was manual. So, the effective parameters of eel movement were investigated. The smooth particle hydrodynamic method was not use, because of saving on time. Therefore, fluent software was used. UDF were added to the fluent software, which it can be move the boundary layer of mesh with eel movement. The dynamic mesh tools of fluent software were used. Initial shape had a curvature and utilized for... 

Finding suitable locations for installing conventional concentric bracings such as X and V, without interfering with building architecture and its openings, is a routine challenge in building design. One of the less known forms of concentric bracings which can be used to solve this issue, is the y-shaped bracing composed of three braces. In the current thesis, results of analytical studies, computer modeling and experimental tests are presented to extend the knowledge of structural behavior of y-bracings. As the first step, effective buckling lengths of braces with rigid connections were found from equilibrium equations incorporating the effect of axial force on rotational stiffness of... 

The everyday increasing electricity consumption of household and industrial sectors across the world, and also the limited generation capacity and fuel supplies has led electricity companies, whether in private or government sectors, to focus deliberately on power generation planning, its costs, risks and constraints Because of many reasons including high efficiency, low cost of capital investment, expeditious permitting, and operation flexibility of gas-fired generating units, electricity companies prefer them to old ones like coal-fired or oil-fired generating units. Thus natural gas has gained a significant share in the portfolio of electricity generation fuel resources, and it is... 

Reviewing the literature on air traffic flow management shows that reducing flight delay is one of the main challenges facing air transportation systems. This is due to the high cost of incurring delays. At the first stage, two mixed integer-programming model is presented here that aims to minimize delay cost of air traffic. The first presented model seeks to minimize flights delay costs by choosing an optimal airport configuration and balancing departure and arrival flights and the second presented model solve this problem with the new approach with categorizing the airplane by types and prioritizing them. Numerical examples are solved in CPLEX 12.6 to evaluate models performance. Numeric... 

external radiation therapy is a methods of cancer treatment or improvement of cancer-related complications. various techniques have been developed for external beam radiation therapy. Among which, Intensity Modulated Radiation Therapy (IMRT), due to its ability to adjust the intensity of radiation beams, has a higher capacity to generate appropriate dose distribution based on tumor size and volume. Intensity Modulated Radiation Therapy is one of the most commonly used procedures of delivering radiation to cancerous tissues, with the aim of reaching the prescripted dose in the target volume while minimizing damage to nearby healthy organs. Two decisions are of fundamental importance: to... 

For more than a million years, aquatic animals and specially fishes make undulatory motions in their flexible body to propel themselves. In the recent decays, scientists prove that these mechanisms are more efficient than man-made propulsion systems. A wide variety of artificial vehicles including robotfishes, ROV and etc has been manufactured with inspiring by natural creatures. The Biomimetic science which deals with the study of mechanics and hydrodynamics of living creatures is very important in developing these vehicles. In the present study, numerical software (PANEL3D®), bases on boundary integral equations of potential flow have been developed to simulate hydrodynamic performance of... 

Land sourced marine pollution, overexploitation of living marine resources, destruction of habitat and introduction of harmful aquatic organisms and pathogens to new environment had been identified as the four greatest threats to the world’s oceans. Since invasive species can not be cleaned or absorbed in the ocean so, their effects on the environment are irreversible. Red tide is one of the invasive spieces and is a colloquial term used to refer to one of a variety of natural phenomena known as algal bloom. This phenomenon occur in estuarine, marine, or fresh water and algae accumulate rapidly in the water column and resulting in coloration of the surface water, varying in colour normally... 

Nowadays, investigating the factors affecting traffic models from different aspects such as metropolitan planning according to the present conditions can help high-level decision-makers and also, at the micro-level, help the travelers to make appropriate decisions for scheduling affairs, route selection, and vehicle type selection. Given the importance of this topic, a framework will be presented in this study that will evaluate the impact of some identified factors such as travel distance, climate, and urban events, and then all these factors will be presented in mathematical formulas. In the end, based on the model, the travel time will be predicted. In this framework, gene expression... 

The design of an indicator for "quality rate measurement" has been done in many countries around the world, and the quality rate, like other economic indicators, is subject to public judgment. Prerequisite for the formation of this index is the existence of a "comprehensive system" for quality management in the country, in which the duties and powers of various institutions in the issue of quality are specified and responsible for each process. With this excellent system, quality management is done in an integrated manner and quality can be managed efficiently by providing indicators.Quality assessment, in addition to hearing the customer's voice, requires other aspects, including examining... 

In this article we have investigated an inventory control model with uncertainly in supply and capacity constraints in the volume and variety of goods for supply chain of chain toy stores. The purpose of model is to minimize inventory costs, ordering cost and the cost of shortage to develop an acceptable customer service level. In order to execute replenishment process of goods we propose three periodic review inventory control policies that are implemented automatic, step by step and by using indicators defined in this article. The major difference between the proposed policies and the as-is policy is to use categorization od goods based on specific characteristics. Each of the three... 

In this thesis we will focus on operating room scheduling considering open strategy and uncertainty in the duration of operations for elective patients. A mixed integer programming model will be proposed having the expected list of patients that are going to be scheduled in the specific time horizon and working hours of doctors with the purpose of maximizing the number of scheduled elective patients in the determined time horizon. We aim to assign each patient to an operating room and a start time regarding operating rooms and surgeons working hours, care units capacity constraints and sequencing constraints. We will define three possible ways for each patient after their operations, naming... 

The nickel-based superalloys play a key role in the development of aircraft and power-generation turbines due to their exceptional properties of high temperature strength, toughness, crack growth resistance and resistance to degradation corrosive and oxidisation environment.In this thesis, the role of base metal composition in isothermal solidification time during diffusion brazing of Nickel-based super alloys was investigated. To achieve this aim, four different super alloys Hynes230, Hastalloy X, Nimonic 263 and Monel were used in similar joining systems. Systems of H230/H230, HX/HX, C263/C263, and Monel/Monel were joined by BNi2 interlayer at 1323K and for different times, until the... 

Today, many real-world datasets such as social network data and web pages can be shown as graphs. Community detection and clustering of these big graphs has many applications in different fields like recommender systems in social networks and Diag- nosis of diseases in communication networks among proteins. A cluster in a graph is a sub-graph with many internal and few external edges. A new method for local cluster detection around an existing vertex is introduced in this paper. This method applies random walk algorithm for cluster detection. The time complexity of this algorithm based on the graph size is polynomial. Therefore, it can be used for clustering of big graphs. The experimental... 

Predicting the trend of stock prices is always one of the concerns that stock market analysts and investors face with, which plays a critical role in maximizing the profit from investing in stocks. Past stock price charts, raw material prices, the value of the company's assets, the impact of global markets, the company's products, the organization's development plans, and the same other factors influencing the stock price. News reports are an important source of information for people. Recently, a lot of research has been done to examine the impact of news on stock price trends. This research has two research phases. In the first phase, a text mining method is presented which is using... 

Performing analysis and forecasting is crucial. Better forecasting will lead to better decisions. One method for predicting the future is time series analysis. In reality, it is common for an intervention to occur and alter the characteristics of a time series. In recent years, interrupted time series analysis has been receiving a lot of attention. A new forecasting method for interrupted time series has been developed in this study. This is a system dynamics-based approach. At every stage of the approach, system thinking is incorporated. In order to model the effects of a given intervention, common modes of behavior in dynamic systems are used. Furthermore, control theory has been used to... 

In recent years, the cosmetics industry has dramatically grown in e-commerce. In e-commerce platforms, where multiple choices are available, an efficient recommender system is required to sort, order, and effectively transfer relevant content or product information to users. Recommender systems have attracted a lot of attention from retailers because they provide consumers with a personalized shopping experience. With technological advancements, this branch of artificial intelligence exhibits great potential in imaging, analysis, classification, and segmentation. Despite the great potential, the academic articles in this field are limited. Therefore, we conducted research in this context, in... 

Using an efficient method to manage inventory systems is always a challenging issue in supply chain optimization. In supply chains including perishable goods, it is possible to reduce waste and other costs by identifying uncertain demand patterns and managing inventory levels at different stages of the supply chain. Considering the uncertainty and complex conditions of supply chains in the real world, in order to create a suitable model to express these conditions, various uncertain factors must be considered, each of which affects the supply chain inventory level in some way. In this research, a multi-level perishable supply chain model with uncertain demand, lead time and deterioration... 

Dynamic increasing amplitude and period (DIAP) [1] is a time-domain analysis methodology developed based on endurance time (ET) analysis method [2], which can be used to evaluate the response of marine structures when encounters a continuous loading, such as storm conditions. In this method, instead of using separate records with different intensities, a single loading record with an increasing intensity over time is used for structural analysis. The ability to enter spectral concepts, considering the effects of waves with different frequencies and amplitudes, taking into account the effects of randomness of waves and the possibility of short duration analysis are some of the specific...