Sharif Digital Repository

Proteins are of fundamental importance for life on Earth and participate in virtually every process within cells. The function of a protein depends on its three dimensional structure. If this is disrupted, the protein loses its biological activity. In addition to temperature, pressure and ionic strength, pH is also an important factor that affects the configuration of proteins. Proteins contain acidic and basic residues. Variations in pH lead to changes in distribution of atomic charge, which in turn affect the stability and function of proteins. Protein folding occurs in a specific pH range, a deviation from which may facilitate misfolding or Amyloid aggregation. It is therefore necessary... 

Nanosized CdS coupled TiO2 nanocrystals were prepared by a microemulsion-mediated Hydrothermal method at relatively low temperatures. Modification of this nanocomposite with Tyrosine,Phenylalanine,Glysine and Glutamate ,especially Tyrosine resulted in enhanced photocatalytic degradation rate of Nitrobenzene( NB ) compared to using CdS-TiO2 under visible light irradiation. The prepared samples were characterized by BET,SEM, XRD, UV–Vis spectroscopy ,FTIR .It was found which have high surface area about 470 m2 g−1 and mesoporous character with the average pore diameter of 2.8 nm.The results showed this nanocomposite consisted of uniform anatase TiO2 with highly dispersed cubic phase CdS... 

Soil-structure interaction has significant effect on dynamic behavior of the super structure. This effect is usually investigated in two separate parts, i.e., the Kinematic Interaction effect and the Inertial Interaction effect. The first modifies the input ground motion to the foundation as a result of difference in soil and foundation stiffness. The later, i.e., the II effect, introduces the effect of soil flexibility and radiation of waves into the supporting medium on the response of the structure. These effects are usually considered by introducing a replacement oscillator with modified natural period and damping ratio subjected... 

Adaptive beamforming performance is very sensitive to any mismatch between actual and presumed steering vectors of desired signal. In addition to this sensitivity, presence of desired signal in training snapshots dramatically reduces the convergence rate, as compared to the case that signal-free training snapshots are available.
The present work is aimed at proposing a new adaptive beamformer that is robust against direction-of-arrival (DOA) mismatch and has high convergence rate. This method is based on desired signal elimination from training snapshots and sub-array beamforming technique. To this end, a Blocking matrix that converts primary data to desired signal free data is... 

The water level of Lake Urmia has experienced a drop of 7.83 meters, from 1995 to 2017. According to previous studies, the uncontrolled development of agriculture, high consumption cultivation pattern, overuse of water resources for agricultural use and high water loss due to low irrigation efficiency, are the most important factors in the drying of Lake Urmia. Since agricultural sector is the largest water consumer (approximately 90%), the Lake Urmia Restoration Program has decided to study and implement the 40% reduction of water consumption in agricultural sector plans.Due to the inherent complexity of the Urmia Lake basin, accurate and realistic evaluation of the effectiveness of the... 

In this research with Finite Element Method in ABAQUS, a Number of Numerical modeling has done in two-dimensions, which can be used to determic the effect of different factors on the seismic vulnerability of tunnels. Also, varios factor such as Geotechnical conditions, tunnel depth, tunnel thickness and ground water is considered in this study.One of the parameters considered in designing tunnels is the ability of the tunnel’s lining to withstand the seismic and geotechnical loads. Each section of the tunnels are designed according to the maximum stress witch created due to the earthquake. this stress’s created in tunnels can be devided in to 3 category : the axial force,the Shear force and... 

With population growth, increased energy demand, and industrial activity, the amount of environmental pollutant emissions, including carbon dioxide, has risen, leading to climate change. This has resulted in the adoption of policies and decisions aimed at reducing emissions and combating climate change. Currently, the primary source of energy for societies is fossil fuels, and according to forecasts, the complete substitution of these resources in the near future is not feasible. Therefore, appropriate solutions must be considered for this transitional period to manage fossil fuel consumption while mitigating emissions and climate change. Carbon Capture and Utilization is recognized as one... 

Train-induced vibrations may become a source of annoyance to the residential environments and disturb the vibration-sensitive instruments. This paper aims to numerically study train-induced vibrations and affecting parameters such as foundation of the building adjacent to the railway, soil stiffness value and its variation pattern in depth and the train speed. To this end, a plane strain model was developed using finite difference program, FLAC2D. In order to simulate possible material damping of soil subjected to dynamic loading, hysteretic damping is incorporated into the model. The results of analyses performed in this study showed that increasing the train speed may not lead to an... 

One of the most widely discussed parameters in energy economics is the price elasticity of gasoline demand due to its substantial implications for taxation, energy efficiency, and environmental policies. This paper aims to estimate the price elasticity of gasoline demand using a novel source of data. The data is from Iran, in the early months of 2014. Vehicles get a quota of 60 liters per month as subsidized gasoline at a lower price. The quota is transferable to the next months if it has not been consumed. All of the information about each pumping transaction is gathered in a centralized database, assigning a unique fuel card to each vehicle. Consequently, the structure of the market provides... 

In this study, an adaptive controller design for nonlinear fractional order systems in the strict-feedback form has been investigated. The system is subject to unknown dynamics, unmeasured state variables, quantized input and output, and input nonlinearity. A linear observer is used to solve the problem of unmeasured state variables. The fuzzy logic system is used to estimate the unknown functions, and instead of updating all the regressor weights, only the upper bound of their norms is updated, which significantly reduces the computational load. In the controller design, limitations due to the bandwidth of data transmission have been considered by applying quantizers in the input and output... 

This study investigates the dynamics of a two-mass oscillator travelling on a viscoelastic rectangular plate under both accelerating/decelerating and uniform motions, while accounting for surface roughness and various reattachment scenarios. Despite its practical significance, this topic has received limited attention in scholarly literature. The Current article studies how key parameters—including the oscillator’s initial velocity, acceleration, foundation/oscillator damping and stiffness, as well as impact type (elastic, plastic, and elastoplastic)—affect the system’s dynamic response. It also examines, via illustrative examples, the oscillator’s motion along paths parallel and diagonal to... 

High-quality online services demand reliable and fast packet delivery at the network layer. However, clear evidence documents the existence of compromised routers in the ISP and enterprise networks, threatening network availability and reliability. A compromised router can stealthily drop, modify, inject, or delay packets in the forwarding path to launch Denial-of-Service, surveillance, man-in-the-middle attacks, etc. So researches tried to create intrusion detection methods to identify adversarial routers and switches. To this end, data-plane fault localization (FL) aims to identify faulty links and is an effective means of achieving high network availability. FL protocols use... 

Confining nematic liquid crystal between two curved boundary conditions while the nematic molecules have a degenerate planar anchoring leads to complex and beautiful textures of molecular disparagement(defect) in the bulk and on the surfaces. Such the liquid crystal shells are made with double-emulsion techniques in microfluidic devices have provided applications for micro-scale colloidal linkers.In this work, we have numerically minimized the elastic energy in one-constant approximation in present of Fournier’s degenerate surface potential with finite element method. The nematic shell is confined between two spherical surfaces that we have studied the final energies and their related... 

The abstract is the most important section of the thesis because many readers limit most of their reading to abstracts, saving in-depth reading for specific theses. It should give the reader a "preview" of what's to come. The abstract should emphasize new and important aspects of the study or observations. The purpose of the abstract is to allow researchers to decide whether or not to read the whole thesis. The abstract is what researchers read first to decide if the thesis is important, interesting, and it allows them to assess the relevance of a thesis to their own research, without having to read the entire thesis. Thus, it is crucial that the abstract both summarize succinctly the key... 

A liquid crystal is a state of matter composed of highly anisotropic building blocks. When liquid crystals are exposed to surfaces with given shapes and anchoring conditions, the orientation of their molecules gets spatially disordered and topological defects may form in the system. The interplay between liquid crystals and the geometry and topology of the colloidal particles has motivated extensive recent studies.In this thesis, we present the numerical modeling results for two faceted colloidal particles in a thermotropic nematic liquid crystal. To obtain the equilibrium nematic field with a finiteelement method, we numerically minimize the free energy of the system that based on the... 

Providing high bandwidth network infrastructures for ever increasing need of data transport is of great importance. The underling infrastructure for many communication services such as GSM/3G/4G mobile networks and Internet services is Synchronous Digital Hierarchy (SDH) optical transport systems. SDH are standardized protocols that multiplex multiple lower rate digital bit streams, such as E1 and Ethernet, and transfer them synchronously over optical fiber using lasers or LEDs. In addition to high data transfer rates, flexible network management and protection mechanisms have great importance, hence are part of SDH standards. In order to obtain flexible network architecture and protected... 

Development of Smart Grid and deployment of smart meters in large scale has raised a lot of concerns regarding customers’ privacy. Consequently, several schemes have been proposed to overcome the above mentioned issue. These schemes mainly rely on data aggregation as a method of protecting users’ privacy from the grid operators. However, the main problem with most of these schemes is the fact that they require a large amount of processing power at the meter side. This, together with the fact that smart meters don’t usually have a powerful processor, can cause the unavailability of smart meter data at the required time for operators of the grid, and at the same time disables smart meters from... 

Secure routing is a major key to service maintenance in wireless ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. Wormhole attack is one of the most severe active attacks to mobile ad hoc networks. Noting the resource limitations in such networks, nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a...