Sharif Digital Repository

We study the spatial and orientational distribution of charged nanorods (rodlike counterions) as well as the effective interaction mediated by them between two plane-parallel surfaces that carry fixed (quenched) heterogeneous charge distributions. The nanorods are assumed to have an internal charge distribution, specified by a multivalent monopolar moment and a finite quadrupolar moment, and the quenched surface charge is assumed to be randomly distributed with equal mean and variance on the two surfaces. While equally charged surfaces are known to repel within the traditional mean-field theories, the presence of multivalent counterions has been shown to cause attractive interactions between... 

We have derived an analytical equation of state (EOS) based on the soft-core statistical mechanical perturbation theory for fluids, using the Weeks-Chandler-Andersen (WCA) theory recently developed by Ben-Amotz-Stell (BAS) for the choice of the hard-sphere diameter, but with a new algorithm for calculation of the pair and many-body interactions. We have used Carnahan-Starling expression with the Boltzmann factor criterion (BFC) as an effective hard-sphere diameter for the reference system, and also decomposed the perturbed pair potential to symmetric and asymmetric terms. The former term is due to the many-body interactions at high densities as was used in the linear isotherm regularity... 

Response-only identification of civil structureshas attracted much attention during recent years, as input excitations are rarely measurable for ambient vibrations. Although various techniques have been developed by which identification can be carried out using ambient responses, these techniques are generally not applicable to non-stationary excitations that structures experience during moderate-to-severe earthquakes. Recently, the authors proposed a new response-only modal identification method that is applicable to strong shaking data. This new method is highly attractive for cases in which the true input motions are unavailable. For example, when soil-structure interaction effects are... 

This paper examines the role of transportation demand management (TDM) policies on commuters' mode choice in the city of Tehran. The analysis is based on the results of a stated preferences survey developed through the design of experiments approach. Five policies covering increasing parking cost, increasing fuel cost, cordon pricing, transit time reduction, and transit access improvement are assessed in order to study their impact on commuters' consideration of six modes of transportation to travel to work. A multinomial logit model was developed for the 366 commuters who regularly commute to their workplace in the center of the city. In addition to a number of commuting and contextual... 

Considering the significant growth in mobile phone use by customers and its high accessibility, this device can be considered as the most suitable tool in payment category. To implement a mobile payment service, there are many actors involved such as: bank, operator and service provider. As an effective interaction role and in order to optimize efficient parameters for implementing a mobile payment solution, it is necessary to present a suitable business model. Therefore, five different business models have been surveyed in the field of mobile payment in this research; then they were compared with MCDM evaluation method applications. Since one of the most effective parameter to select an... 

Air-handling unit (AHU) is one of the most complex installations that its control is necessary for maintaining satisfactory comfort conditions in buildings with low energy utilization. In this paper, a multivariable nonlinear and minimum phase model of the AHU is considered in the presence of uncertainties. The controller design is divided into two types. The first controller type is for the linearized plant based on decoupled PID-Fuzzy and PD-type Fuzzy controllers. The second type is based on full matrix PID-Fuzzy and pole-placement controllers in which interaction effects are considered. The indoor temperature and relative humidity are controlled via manipulation of valve positions of air... 

In this study, for the first time a statistical analysis based on the response surface methodology (RSM) was employed to investigate individual and interaction effects of key operating parameters of the photocatalytic degradation under visible-light irradiation using Ag-S/PEG/TiO2. Ag-S/PEG/TiO2 is a visible-light-driven photocatalyst and was synthesized (based on earlier research) by co-doping of TiO2 with silver and sulphur and addition of polyethylene glycol (as a reagent template). In addition, the model pollutant was methylene orange (MO) and the studied operating parameters included the photocatalyst loading, initial concentration of the pollutant, and pH of the solution. The... 

Due to increased atherosclerosis-caused mortality, identification of its genesis and development is of great importance. Although, key factors of the origin of the disease is still unknown, it is widely believed that cholesterol particle penetration and accumulation in arterial wall is mainly responsible for further wall thickening and decreased rate of blood flow during a gradual progression. To date, various effective components are recognized whose simultaneous consideration would lead to a more accurate approximation of Low Density Lipoprotein (LDL) distribution within the wall. In this research, a multilayer Fluid-Structure Interaction (FSI) model is studied to simulate the penetration... 

This paper presents the probabilistic generation of collapse fragility curves for evaluating the performance of 3D, reinforced concrete (RC) moment-resisting building models, considering soil-structure interaction (SSI) by concentration on seismic uncertainties. It considers collapse as the loss of lateral load-resisting capacity of the building structures due to severe ground shaking and consequent large interstory drifts intensified by P-Δ effects as well as the strength and stiffness deterioration of their lateral load carrying systems. The estimation of the collapse performance of structures requires the relation between the intensity measure (IM) and the probability of collapse... 

The increase of underground space applications, as a solution for congested urban areas makes it inevitable to cross closely spaced underground structures. The analysis of new TBM EPB-bored tunnel under existing underground station was conducted by 3D finite element method. The influence of new tunneling was investigated on the deformation and moments of final lining of existing underground station. The effectiveness of interaction analysis depends on factors such as station overburden, existing station supporting stiffness and traffic loads. In this paper, a parametric study was conducted to study ground movements and lining moments. It is shown that moment increase is significant when the... 

The increase of underground space applications, as a solution for congested urban areas makes it inevitable to cross closely spaced underground structures. The analysis of new TBM EPB-bored tunnel under existing underground station was conducted by 3D finite element method. The influence of new tunneling was investigated on the deformation and moments of final lining of existing underground station. The effectiveness of interaction analysis depends on factors such as station overburden, existing station supporting stiffness and traffic loads. In this paper, a parametric study was conducted to study ground movements and lining moments. It is shown that moment increase is significant when the... 

This paper presents an analytical study of swarm motion in static environments, in which, motion of the swarm is modeled as a quasi static model. Motion of each member is being affected by interactive forces and environmental effects. Interactive effects on each member could be attractive or repulsive due to being far from or close to other members respectively. Environmental effects also could be attractive or repulsive or a combination of both. The method is based on Lyapunov analysis. Two objectives are investigated through the analysis; one is to preserve the unity of swarm i.e. not losing any member through motion, and the other is to move toward attractant areas and away from repellant... 

Recently, the traditional strength-based design (SBD) philosophy is being replaced by more relevant displacement-based design (DBD) approach. As a main step, DBD method requires a simplified procedure to estimate the inelastic displacement demands of the structure. This step is usually done by either replacing the non-linear system by an equivalent linear system or employing the well-known concepts of inelastic design spectra. The application of different DBD procedures and their deficiencies, thus, have been the subject of numerous researches during the recent years. However, the effect of soil is usually ignored. On the other hand, it is well-known that soil affects the structural behavior... 

The electrohydrodynamic (EHD) 3D printing technology is an Additive Manufacturing (AM) method that can be used in the manufacture of submicron-size structures. In this process, which is based on the formation of Taylor jet from a metallic ink, the investigation of particles reaction and aggregate formation in ink during printing is of great importance. In this paper, a new Finite Element model based on particle tracing in fluids is presented that couples the different physics that govern an EHD phenomenon. Vortex flow caused by boundary shear stress was observed in the ink jet; which was more like the Marangoni phenomenon in a stationary drop. By experimentally validating the presented model... 

Damage assessment of concrete arch dams is carried out through nonlinear Incremental Dynamic Analysis (IDA) of a typical arch dam. In this study the Morrow Point arch dam is subjected to a set of 12 three-component earthquakes each scaled to 12 increasing intensity levels. The dam-foundation interaction effects have been investigated by varying foundation's modulus of elasticity to be equal and half of dam concrete's modulus of elasticity. Damage propagation through the dam body is investigated and various IDA curves are created. The performance and various limit-states of the dam structure are examined based on the obtained results. Simple damage indices are proposed through comparison of... 

Modeling passengers' itinerary choice behavior helps in understanding the increasingly competitive airline market and in predicting air travel demand. Recently, investigation of the variation in passengers' preferences with regard to factors influencing their choice through estimation of the mixed multinomial logit model has received attention. An extended form of the model identifies sources of heterogeneity and consequently makes the choice models less restrictive in considering both systematic and random preference variation across individuals. This research investigates the existence of significant interactions between passengers' preference heterogeneity around the mean of random... 

The aim of this paper is to study the influence of frequency in pulse electrodeposition, on the current efficiency, Ni content and surface morphology of deposits from a novel cyanide-citrate electrolyte with 20 mM gold as KAu(CN) 2 and 7 mM NiSO 4, with the aim of design of experiment by respond surface method (RSM). Frequency was in the range of 1-200 Hz in constant average current density, temperature, and duty cycle of 7 mA/cm 2, 59 °C and 55% respectively. Composition of the deposits was determined by atomic absorption spectroscopy (AAS). Additionally, deposits were characterized by scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDS). It was shown that from... 

The water-gas shift reaction occurs competitively to the main reaction of the Ir-catalysed methanol carbonylation process. To study the effect of seven factors including temperature, pressure, iridium, ruthenium, methyl iodide, methyl acetate and water concentrations on the formation of hydrogen and carbon dioxide as a result of the water-gas shift reaction and other side reactions in the carbonylation of methanol to acetic acid, the experimental design method combined with response surface methodology (RSM) was utilised. Central composite design at five levels (with α=1.63) was used to design experiments. A quadratic model that included the main and interaction effects of variables for H 2... 

Upon incorporation of nanoparticles (NPs) into the body, they are exposed to biological fluids, and their interaction with the dissolved biomolecules leads to the formation of the so-called protein corona on the surface of the NPs. The composition of the corona plays a crucial role in the biological fate of the NPs. While the effects of various physicochemical parameters on the composition of the corona have been explored in depth, the role of temperature upon its formation has received much less attention. In this work, we have probed the effect of temperature on the protein composition on the surface of a set of NPs with various surface chemistries and electric charges. Our results... 

Due to increased atherosclerosis-caused mortality, identification of its genesis and development is of great importance. Although, key factors of the origin of the disease is still unknown, it is widely believed that cholesterol particle penetration and accumulation in arterial wall is mainly responsible for further wall thickening and decreased rate of blood flow during a gradual progression. To date, various effective components are recognized whose simultaneous consideration would lead to a more accurate approximation of Low Density Lipoprotein (LDL) distribution within the wall. In this research, a multilayer Fluid-Structure Interaction (FSI) model is studied to simulate the penetration...