Sharif Digital Repository

Human body movements are achieved by activating a number of muscles. It has been shown that the central nervous system (CNS) plays the main role in controlling rhythmic activities (including walking, chewing, etc.). However, the way the central nervous system works in controlling different parts of the body has always been discussed due to the excess degrees of freedom to perform certain tasks. Controlling a group of muscles (under the name of muscle synergy analysis) instead of each one of them has been one of the most attractive and efficient recent ideas to better understand the CNS function. Also, a similar concept can be expressed for kinematic synergies (by the degrees of freedom of... 

Polymerase chain reaction, abbreviated as PCR, is a method of amplifying the number of copies of a desired DNA sequence through special protocols. The rapid advance of microfluidic devices and the emerging concept of digital microfluidics has resulted into the development of digital droplet PCR (ddPCR) systems with their significant uses in the detection of rare mutations, cancer diagnosis, and surveillance. A large number of micron-sized droplets are required to perform ddPCR. in this study, To investigate the gradient of confinements induced droplet self-breakup mechanism, we carried out the computational fluid dynamics (CFD) simulations for the two-phase flow using a commercial software... 

In this study, the attitude control of an under-actuated satellite has been investigated. The investigated satellite uses reaction wheels for attitude control. For having full controllability of a satellite attitude, at least three reaction wheels are required. However, due to the high failure rate of reaction wheels, in this study assumed the satellite has two perpendicular reaction wheels, which causes the satellite to be under-actuated. The path planning method is used for controlling the satellite, which is an offline method. In the beginning, tries to define the control input of the satellite in term of limited parameters with different methods. In this regard, the control input is... 

Lifting is considered a major risk to people's health in life, particularly to the workers. Appropriate wearable tools for measuring the individual’s kinematic and kinetic movement are required for examining and analyzing the lifting activity to prevent injury in the workplace. Different wearable systems have been developed to calculate the force applied on the foot sole to analyze movement in various areas of gait analysis, occupational biomechanics, sports, and other areas. The accuracy and precision of these systems need to be tested before application in any of these areas. In this study, 3 subjects performed five different activities of symmetrical lifting by placing Pedar insoles in... 

Many heart attacks and strokes are caused by improper clot formation in the vascular system. Mathematical understanding of the clot formation process and the influence of various factors in the clot formation process is very important. In this study, the aim is to simulate and understand the clotting process mathematically by considering natural, external and general mechanisms in the clotting process. In this process, when damage occurs in the endothelial region of the vessel, tissue factor is released and 38 different substances react with each other inside the plasma, eventually forming fibrin. To simulate the movement of different chemical components and proteins in plasma, the... 

Cerebral palsy (CP) is one of the most common diseases that cause by brain injury or abnormalcy and occur while brain is developing before, during or just after birth. people with cerebral palsy face certain problems associated with the control of their muscles, these conditions will make simple activities such as sitting, walking or taking objects very difficult for a person.In the case of gait analysis and its effectiveness, there are many articles and studies. In general, experts have used gait analysis to diagnose and treat problems in cerebral palsy patients. Experts have studied on cerebral Palsy using gait analysis directly and indirectly. In indirect cases, patients are classified... 

Polymerase chain reaction method is a conventional method for obtaining multiple copies of a specified segment in the DNA molecule and to amplify the DNA molecule itself. Therefore, this method has been of paramount importance in different fields of research and has been applied for different applications. PCR requires thermal cycling, or repeated temperature changes between two or three discrete temperatures to amplify specific nucleic acid target sequences. To achieve such thermal cycling, conventional bench-top thermal cyclers generally use a metal heating block powered by Peltier elements or benefit from forced convection heat transfer. Although efforts have been made in order to reduce... 

Polymerase chain reaction, abbreviated as PCR, is a method of amplifying the number of copies of a desired DNA sequence through special protocols. The rapid advance of microfluidic devices and the emerging concept of digital microfluidics has resulted into the development of digital droplet PCR (ddPCR) systems with their significant uses in the detection of rare mutations, cancer diagnosis, and surveillance. In this study, an integrated ddPCR microfluidic chip alongside its thermoelectric thermal cycler and optical analysis systems have been designed, fabricated and their performance has been tested and evaluated. It was shown that the effect of master mold’s surface quality, the material of... 

Deep reactive ion etching is one of the most used techniques for manufacturing micro-structures. The most popular silicon DRIE technique is Bosch process. Ability to manufacture high aspect ratio features made Bosch process the main technique for developing micro-electromechanical devices. Dry etching is a combination of physical and chemical processes. The chemical processes play a very important role due to their speed of material removing and also due to their high selectivity. Also chemical processes are responsible for development of passive resist layer on the surface. On the other hand, if not controlled properly it can reduce anisotropy, resulting in a low quality etch. In this... 

Nowadays, technology has facilitate the miniaturization of laboratory systems, medical and drug delivery tools. As a result, researchers are interested to miniaturize these tools. The extensive research in this field led to invention of lab-on-a-chips, which with the size of a few µm to a few mm, can do multiple tasks in human body. One of most important components of these devices, is microreactor. A wide range of measurements and reactions in microreactors, need to bind with the receptors at the surface of the cylindrical microchannels. For this purpose, this study, investigates the effects of surface heterogeneity on microreactors performance. In this Thesis, the governing equations were... 

In this research, modelling of pyrolysis in small-scale and a method for calculation of kinetic parameters; activation energy, pre-exponential factor, and model function, have been presented. Calculation of activation energy and frequency factor without any assumption on model function heve been done by presented method. Because, incorrect assumption on model function can be cause to error in estimated values of activation energy and frequency factor.For a bench-scale sample, the heat transfer and mass conservations equations influence the pyrolysis process. In this research for the investigation of kinetic parameter effects, a simple pyrolysis model was presented to predicting the mass flux... 

Lameness in dairy cattle is a crucial welfare issue after infertility and mastitis in dairy industry, and over the years scientists are attempting to present a detection method. In recent it is attracting more attention to make the identification and discrimination of sounds and lames systematic and automatic. Right now, the most hopeful results have been obtained through the measurement of Ground Reaction Forces (GRF) of hooves, and analysis of load distribution between four legs, which seems applicable for wide use in dairy industry.However, the accuracy, validity, and reliability of discrimination is still far from an acceptable point, that is because of a great lack in understanding... 

Lameness in dairy cattle is a crucial welfare issue in dairy industry, and over the years scientists are attempting to present a detection method. In recent years it is attracting more attention to make the identification and discrimination of sounds and lames systematic and automatic. Right now, the most hopeful results have been obtained through the measurement of Ground Reaction Forces (GRF) of hooves, and analysis of load distribution between four legs, which seems applicable for wide use in dairy industry. However, the accuracy, validity, and reliability of discrimination is still far from an acceptable point, that is because of a great lack in understanding quantitative effects of the... 

Porous burner technology has many advantages in comparison with conventional burners such as higher burner thermal performance, lower pollutants emission, high power ranges, fuel flexibility, compact geometry and higher turn down ratios. These kinds of burners are made of preheated porous combustion zone and combustion porous zone that have different thermophysical and geometrical properties. In this work, the transient one-dimensional multi-step premixed laminar reacting flows in a two-stage porous media burner have been investigated. The combustible mixture is considered H2-Air (9 species and 19 reactions) and CH4-Air (22 species and 49 reactions). In porous media, without lateral wall... 

The development of alternative energy sources is a prominent area of scientific research. Hydrogen, with its exceptional energy density, has emerged as a particularly promising candidate among these new energy sources. An effective technique for generating hydrogen is through the electrochemical process of water splitting. To enhance this process, it is crucial to investigate the development of electrocatalysts with high electrocatalytic activity. Among the potential options, sulfides of transition metals show promise. An essential difficulty in electrochemical water splitting is the development of a bifunctional catalyst that is both active and stable for both the hydrogen evolution... 

Nowadays, with the increasing number of polyethylene terephthalate wastes, the issue of its recycling has become very important. Among the problems of polyethylene terephthalate recycling are its loss of crystallinity and mechanical properties. Recycled polyethylene terephthalate does not have the properties of new polyethylene terephthalate and using its mixture with other materials is an effective way to remove its waste from nature and return it to the production cycle. The aim of this study is to produce a mixture of recycled polyethylene terephthalate with polycarbonate and glass fibers with mechanical properties such as good impact strength, which ultimately leads to the production of... 

The air cathode of li-air batteries has been identified as a key factor affecting the overall performance of Li-air batteries. Graphene-based cathodes have been investigated as cathode catalysts for lithium-air batteries due to their high activity in accelerating and facilitating oxygen reduction reaction (ORR). In this study at first, graphene oxide was synthesized using Hummers’ method, and then it has been reduced via hydrothermal methode. To increase electrocatalytic properties of the sample Cobalt oxide nanoparticles has been precipitated on reduced graphene oxide, and it has also been doped with Nitrogen. Three samples of reduced graphene aerogel (GA), Nitrogen doped graphene aerogel... 

Depleting resources and heavy pollution of fossil fuels have drawn the world's attention to clean energy and the most ideal one is hydrogen. Water splitting is one of the most effective ways to produce hydrogen and due to slow kinetic rate different kind of catalysts (optical, electrochemical, etc.) are developed for this reaction. In this work a ZIF-67 and N-doped graphene quantum dots composite is developed and its electrocatalytic performance in oxygen evolution reaction is evaluated. The synthesized graphene quantum dots are between 2-4 nm and the incorporation of nitrogen atom in their structure was verified by FTIR analysis. The metal-organic framework which is produced in this work... 

The air cathode of li-air batteries plays a pivotal role in the overall performance of Li-air batteries. Graphene-based cathodes have been investigated as cathode catalysts for lithium-air batteries due to their extraordinary potential for accelerating and facilitating oxygen reduction reaction (ORR).In this study graphene oxide have been synthesized via modified Hummers’ method. Consequently, the as obtained graphene oxide have been reduced using chemical, electrochemical, and hydrothermal methods. Results of elechtrochemical evaluations demonstrate that the graphene oxide reduced via hydrothermal method possesses the most positive ORR onset potential (+0.55V vs SHE) among the other samples... 

In this research the process of incomplete reduction of hematite low iron ore to magnetite in a fluidized bed reactor was investigated. Temperature, composition of reduction air, particle size, and stay time were investigated as effective parameters. In this way, temperatures of 560, 580, 600, 620 and 640 degrees of centigrade, input air with flows of 1.2, 1.3 and 1.4 l/s, particles size of 425-850 µm, 850 µm-1.4 mm, and 1.4-2 mm, stay times of 4, 8, 12, 16, and 20 min were used in this research. The reduced specimens were analyzed by XRD and chemical analysis. The results illustrated that increase of temperature, decrease of input air flow, decrease of particles size, and increase of stay...