Sharif Digital Repository

In this article, we will examine the theory of evolution through natural selection and we will show that the evidence in favor of natural selection is so great that today this theory has been fully accepted by the scientific community. The theory of evolution had many philosophical and theological consequences; One of its direct consequences was the weakening of teleological arguments and specifically the argument of William Paley's plan; Because in the light of this theory, the existence of features with functions and complex adaptations of living things can be explained without the need of designing a supernatural agent. Despite this, biology still uses concepts such as function, which has... 

Fog computing environment consists of several devices which distribute across an arbitrary topology. Each of these devices is capable of carrying out a designated computation simultaneously with other devices. One of the common ways of describing a computation is through the usage of workflows. Workflow is a flexible and formal way of modeling tasks and their requirements for execution. A workflow is essentially a DAG. Therefore, it can model the data dependency between tasks quite accurately. The complex structure of a workflow in conjunction with the homogenous nature of devices in a fog environment makes it difficult to find a resource management algorithm to minimize execution time, used... 

This project focuses on the design of fuel drop tanks for airplanes that add minimal drag and positive lift to the flying object. This will obviously effect the stability and dynamic performance of the airplane. To reduce adverse dynamic effects the tank was divided to several segment with a special emptying sequence. The add-on tank has to have no interference with the object existing systems and require minimum structural changes in the object. Several designs were proposed and the one gaining highest marks was selected. The flow field and the dynamic behavior of combined vehicle and drop tanks were studied using FE simulations. The result shows that adding a drop tank with optimized... 

Different perceptual, cognitive, and emotional situations results in a kind of information flow in the brain by means of coordinated neuronal oscillations. Analysing these oscillations, especially synchronizations of different brain regions, can illustrate the brain response to the aforementioned situations. In the literature, connectivity between brain regions is divided into the three groups of structural, effective, and functional, s.t. the first one referes to the connectivity between nearby regions, while the second and third ones focus on the synchronization of oscillations of arbitrary located regions. Although EEG is not the best choice for analyzing functional connectivity between... 

Cancer can be defined as a stochastic phenomenon. Thus, the tumor growth can be defined as a stochastic process. A Cancer tumor can be analyzed by its geometric shape. Furthermore, computing fractal dimension of shapes is a useful technique to analyze chaosity and complexity of shapes. This approach can be used to compare results from laboratory with simulated results of a mathematical model. A stochastic model of tumor growth will be presented. And some geometrical properties will be analyzed through computer simulation of the model  

Nowadays, one of the most basic human problem is how to manage energy resources for sustainable development and how to deal with problems caused by growing energy consumption. Various scenarios are being discussd that the most important of them can be considered research on finding alternative energy sources that are renewable and do not have common pollution. Thus, according to researches carried out until now, using sources such as wind, water, solar biomass, etc. have been proposed. However, due to problems in the development of each of these sources, biomass as the primary option has been introduced. because biomass has several subsidiaries, research shows microalgaes (as a subset) are... 

Today, almost all the country's needs in the field of industrial enzymes are met through imports. In this regard, much attention has been paid to the industrial production of various enzymes in the country. The production of recombinant proteins through strain engineering is one of the most important ways to meet this demand due to its many benefits. One of the most important microorganisms that is widely used in the enzyme industry is Bacillus subtilis. Due to its thick peptidoglycan wall, this gram-positive bacterium hardly accepts engineered carriers for genetic modification as hosts. The aim of this study was to evaluate the permeability of the wall and cell membrane of Bacillus subtilis... 

The effects of combined task demands on the way muscles are recruited to balance external loads during posture and movement is of great importance in quantitative analysis of upper arm function. Pain and disability of shoulder joint is becoming more important as population spends more often interacting with computers in seated position and carrying repetitive tasks using upper extremities. Shoulder joint that is more dependent on the muscles for its normal function than other joints such as hip due to its small articular surface and large range motion has been used here to study its coordination during isometric exertions. Since, the numbers of tasks that could be performed are enormous. In... 

In the present study, the axisymmetric liquid gas/air diffusion flame in the presence of fuel concentration oscillations and velocity perturbations has been investigated experimentally. Several industrial combustions take a place by diffusion mechanism which necessitate scientists to make far better understanding of diffusion flames. In order to study diffusion flames, the instrument with two separated lines of fuel and air has been developed. Nitrogen is used for fuel dilution oscillatory with pulse of 1, 2, and 4 Hz frequencies. The pulse duration effects on flame structure are also studied. The flame shape has been captured by high speed camera and the results are processed by image... 

This research evaluates the effect of external corrosion geometry and bending moment on the burst pressure of pipes. In recent decades, the use of natural resources of offshore oil and gas has increased, as a result, the use of offshore pipelines for transferring products has grown dramatically. At the same time, numerous accidents and explosions in offshore pipelines and its economic and environmental consequences indicates the importance of ensuring safe operation. Pipeline Integrity Management has been developed to ensure safe and efficient operation of pipelines. Integrity management includes planning, inspection, evaluation and repair. This cycle is checked continuously. The importance... 

Burner scaling criteria have been studied and the most appropriate one has been selected to scale down a large industrial burner. The sub-scaled non-premixed swirl-stabilized burner is manufactured to ensure that the available experimental setup and equipment are sufficient and practical for characterizing the burner. The aim of the research is to assist the future design optimization with the identifications which have been done. The constant residence time method is selected in this project and it is shown that this is the proper criteria for non-premixed and swirl-stabilized burners. For better identification, stability maps of the flame are extracted with the experimental methodology for... 

The purpose of this study was to create a three-cationic electro phosphate coating of zinc-nickel-manganese by cathodic method and to investigate the effect of operating variables on the properties of zinc-nickel-manganese tri-cationic electro phosphate coating. Hence, the effects of variables such as coating acidity, coating thickness, coating temperature, coating time and concentration of manganese were studied in the bath on the properties such as coating morphology, corrosion resistance, coating thickness. Coating morphology was characterized by scanning electron microscopy and corrosion resistance by polarization test. The pH values of 1.4, 1.8, 2 and 2.2 were selected, and the results... 

Airport saturation is one of the important issues which have always been of the specialists’ concern. One of the major applications of this subject is at the airport approach problems. While using current conventional approach procedures have many disadvantages regarding high fuel consumption and subsequent much environmental and noise pollution, the CDA concept which is one of the modern topics introduced in consequence of free flight theory, has less such disadvantages compared to conventional approach. Subject of this study is to investigate whether Procedural approach or CDA saturates an aiport sooner if the traffic flow increases. In this dissertation, using BADA database, CDA... 

Study of the structural flexibility of large-scale wind turbine components on aeroelastic performance is important under the existence of critical atmospheric conditions. Prediction and control the critical deformations, identifying maximum local deformation and modeling the forces involved, are required. Aeroelasticity analysis is a suitable method for studying the coupling effects of wind turbine aerodynamics, dynamics and structures. This research has been done by modeling wind turbine components including blades, hub, nacelle and tower, taking into account aerodynamic couplings, dynamics and structures. Considering the large scale of reference wind turbine, nonlinear equations have added... 

Connections have a crucial role in the behavior of every structure. Amongst various types of connections used in steel structures are those used to connect the columns to the foundations, namely Base Plates. As other types of connections, base plates control the behavior of the structure in various respects including affecting the effective length of columns. The main task of any base plate is to distribute the forces of the column on the foundation in such a manner that the stresses in concrete are below their allowable values. Different configurations, with or without various attachments, are used for designing the base plates hence achieving various types of behavior with various levels... 

Networked business is a kind of businesses, relatively new and very complex, worthy of more analysis and study. From all types of networked businesses, “Platform based” ones are subject of this study. To solve “the problem of networked business”, in this study we try to develop a conceptual framework, using different disciplines especially:
- Business model studies
- Network science and social network studies
- Economic and strategic studies of platforms
Besides some new business concepts defined and theorized in this study, reader will find the conceptual architecture, applicable to the general of the business  

Nowadays, Resource Capacity Management (RCM) is one of the main challenges for industries which have a limited capacity to meet the demands. Revenue Management (RM) is a technique that controls the supply, improves the quality of Capacity Management and maximizes the revenue. Supplying the products and services to different groups of customers is a decision making problem.While the classic RM techniques take into account only the expected revenue, preferences of decision makers strongly affect the results. In this study, utility theory has been proposed because the healthcare industries are usually nonprofitable and they are not highly focused on the revenue gained by their products and... 

The purpose of this thesis is presenting some decoupling methods for fractional-order two input-two outputs (TITO) systems in order to using in control applications. To achieve this purpose, some methods which have been proposed for decoupling of integer-order systems have been studied and then generalized to be used in decoupling of the fractional-order systems. These methods are classified in two classes: state space based methods and transfer function based methods. Also, in this thesis the proposed decoupling methods have been used in control of some fractional-order TITO systems