Sharif Digital Repository

In feature-based image registration, feature selection and reduction methods play an important role in decreasing computational burden of these operations. In this paper, a new approach is introduced to reduce the dimension of extracted feature vectors of MR images. This approach is based on the selection of the maximum and minimum responses of the alpha stable filter for the MR images over the extracted features with different orientation in frequency domain. This algorithm selects the rotation invariant features which are suitable for image registration purposes. It has been shown that these features could efficiently describe the image elements. The discriminating ability of the features... 

Ciprofloxacin is a widely used antibiotic that is also a persistent contamination that causes major health and environmental risks. This study investigated the electrochemical removal of ciprofloxacin using a boron-doped diamond anode and a non-supportive electrode to get an accurate understanding of the anode's performance. The effects of current density, initial ciprofloxacin concentration, time, pH, and electrolyte concentration on the removal efficiency of ciprofloxacin were investigated. Additionally, ANN and LSSVM models were used to predict ciprofloxacin removal. The results showed that the BDD anode was effective in removing ciprofloxacin from water, with complete removal of 10 mg... 

Spatially-varying intensity noise is a common source of distortion in medical images and is often associated with reduced accuracy in medical image registration. In this paper, we propose two multi-resolution image registration algorithms based on Empirical Mode Decomposition (EMD) that are robust against additive spatially-varying noise. EMD is a multi-resolution tool that decomposes a signal into several principle patterns and residual components. Our first proposed algorithm (LR-EMD) is based on the registration of EMD feature maps from both floating and reference images in various resolutions. In the second algorithm (AFR-EMD), we first extract a single average feature map based on EMD... 

This paper presents an efficient mixed-integer linear formulation for long term maintenance schedule of overhead lines. The proposed formulation is based on risk management approach and utilizes the model of decoupled risk factors. The proposed methodology yields a significant computational saving comparing to the previously reported dynamic programming. Risk management approach enables the asset managers to consider the actual condition of electrical equipment and expected consequence of their failures. Furthermore, the decoupled risk strategy in conjunction with the mixed-integer linear programming formulation establishes a precise description of time-dependent deterioration failure rate... 

Statistical analysis of non-normal data is usually more complicated than that for normal distribution. In this paper, a simple root/power transformation technique developed by Niaki, et al [1] is extended to transform right and left skewed distributions to nearly normal. The value of the root/power is explored such that the skewness of the transformed data becomes almost zero with an acceptable error. The proposed method is then compared to the well-known and complicated Box, et al [2] transformation method for different left and right skewed distributions using Monte Carlo simulation. While the proposed procedure is easy to understand and to implement, the results of the simulation study... 

Estimation of muscle force is needed for monitoring or control purposes in many studies and applications that include direct human involvement such as control of prosthetic arms and human-robot interaction. A new model is introduced to estimate the force of muscle from the EMG signals. Estimation is based on Hammerstein-Wiener Model which consists of three blocks. These blocks are used to describe the nonlinearity of input and output and linear behavior of the model. The nonlinear network is designed base on the sigmoid network. The introduced model is trained by some data sets which are recorded from different people and tested by some other data sets. The simulation results show low error... 

In this article, ferrohydrodynamic forced-convection heat transfer from a heated sphere embedded in a ferrofluid in the presence of the uniform external magnetic field has been studied numerically for the first time over a wide range of Reynolds number value, nanoparticle diameter, particle volume fraction, and magnetic field intensity. Despite the uniform external magnetic field applied, the internal magnetic field near the sphere could be nonuniform due to the considerable difference between the relative magnetic permeability of the sphere and the surrounding medium. Kelvin body force arises from this nonuniformity and induces vortexes near the sphere. These vortexes disturb the boundary... 

In this study, a new isolated high-gain switched-boost DC/DC converter employing two symmetrical switched-boost networks along with a modified control algorithm based on the combination of the pulse-width modulation (PWM) and phase-shift modulation is proposed. Utilising symmetrical switched-boost networks increase the voltage gain of the proposed converter, significantly. Moreover, applying the proposed switching algorithm on the proposed isolated switched-boost DC/DC converter leads to the following advantages: (i) high-voltage gain, (ii) zero voltage switching (ZVS) turn-on of two switches, (iii) ZVS turnoff of two switches and (iv) appearing three controllable parameters (the... 

In this paper a strategic planning framework is proposed for generation expansion planning of grid-connected micro-power systems. The proposed framework is composed of two different decision making techniques that results a robust planning approach compared to previous techniques to identify the feasible and efficient plans according to attributes and uncertain parameters considered in planning environment. The framework considers the robustness and risk exposure of different configurations according to uncertain parameters in the planning environment to select the plans which meet the objectives more efficiently with least risk exposure. The proposed methodology is implemented for... 

The effectiveness of the application of CFD to vapour cloud explosion (VCE) modelling depends on the accuracy with which geometrical details of the obstacles likely to be encountered by the vapour cloud are represented and the correctness with which turbulence is predicted. This is because the severity of a VCE strongly depends on the types of obstacles encountered by the cloud undergoing combustion; the turbulence generated by the obstacles influences flame speed and feeds the process of explosion through enhanced mixing of fuel and oxidant. In this paper a CFD-based method is proposed on the basis of the author's finding that among the various models available for assessing turbulence, the... 

Graphene oxide membranes were prepared by vacuum and pressurized ultrafiltration methods on the 12% modified Polyacrylonitrile (12mPAN) substrate to specify challenges, salient features, future directions, and potential of GO membrane for separation fields using characterization techniques and gas separation test (studied gases are CO2, He and N2), which is an efficient tool for better understanding of GO membrane behavior. GO membrane structure was examined over a wide range of parameters, such as pore size range of substrate and its surface properties, pH of GO dispersion, GO content, synthesis pressure, operating pressure and temperature. The results show that the GO content does not hold... 

The solubility of Pd(NO3)2 in water is moderate whereas it is completely soluble in diluted HNO3 solution. Pd/MIL-101(Cr) and Pd/MIL-101-NH2(Cr) were synthesized by aqueous solution of Pd(NO3)2 and Pd(NO3)2 solution in dilute HNO3 and used for CO oxidation reaction. The catalysts synthesized with Pd(NO3)2 solution in dilute HNO3 showed lower activity. The aqueous solution of Pd(NO3)2 was used for synthesis of mono-metal Ni, Pd and bimetallic PdNi nanoparticles with various molar ratios supported on MOF. Pd70Ni30/MIL-101(Cr) catalyst showed higher activity than monometallic counterparts and Pd + Ni physical mixture due to the strong synergistic effect of PdNi nanoparticles, high distribution... 

The solubility of Pd(NO3)2 in water is moderate whereas it is completely soluble in diluted HNO3 solution. Pd/MIL-101(Cr) and Pd/MIL-101-NH2(Cr) were synthesized by aqueous solution of Pd(NO3)2 and Pd(NO3)2 solution in dilute HNO3 and used for CO oxidation reaction. The catalysts synthesized with Pd(NO3)2 solution in dilute HNO3 showed lower activity. The aqueous solution of Pd(NO3)2 was used for synthesis of mono-metal Ni, Pd and bimetallic PdNi nanoparticles with various molar ratios supported on MOF. Pd70Ni30/MIL-101(Cr) catalyst showed higher activity than monometallic counterparts and Pd + Ni physical mixture due to the strong synergistic effect of PdNi nanoparticles, high distribution... 

The solubility of Pd(NO3)2 in water is moderate whereas it is completely soluble in diluted HNO3 solution. Pd/MIL-101(Cr) and Pd/MIL-101-NH2(Cr) were synthesized by aqueous solution of Pd(NO3)2 and Pd(NO3)2 solution in dilute HNO3 and used for CO oxidation reaction. The catalysts synthesized with Pd(NO3)2 solution in dilute HNO3 showed lower activity. The aqueous solution of Pd(NO3)2 was used for synthesis of mono-metal Ni, Pd and bimetallic PdNi nanoparticles with various molar ratios supported on MOF. Pd70Ni30/MIL-101(Cr) catalyst showed higher activity than monometallic counterparts and Pd + Ni physical mixture due to the strong synergistic effect of PdNi nanoparticles, high distribution... 

This study forwards a novel and simple approach for encapsulation of Phosphotungstic acid (PTA) into MIL-101(Cr) cavities to develop PTA-MIL-101(Cr) with a high surface area. In this method, the resulting surface area of PTA-MIL-101(Cr) (3563 m2/g) is 1.72 times that of MIL-101(Cr) due to the existence of more accessible pores which are formed by leaching of PTAs incorporated inside MIL-101(Cr) pores during the intense washing. Catalysts are investigated in CO oxidation under atmospheric pressure and feed composition of 1%CO, 20%O2, and 79%He. 3%Pd/PTA-MIL-101(Cr) shows 100%CO conversion at T = 145 °C and outperforms PTA, PTA-MIL-101(Cr), Pd/PTA, 1–3%Pd/MIL-101(Cr), Pd-PTA/MIL-101(Cr), and... 

Numerous advantages of application of tailor welded blanks (TWBs) in automobile industry, namely reduction of weight, fuel consumption and air pollution, have made the manufacturers eager to investigate in this field. On the other hand, while experiments generally provide valuable information in regard with mechanical behaviors, but utilization of simulation methods has extended vastly due to time and cost saving issues. One challenging issue in numerically analyzing the forming behavior of transversely welded TWBs, welded by laser welding methods, has been the presence of weld zone. While some researchers believe that during simulation, the weld zone can be neglected due to its minority and... 

It is always crucial to estimate process capability index (PCI) when the quality characteristic does not follow normal distribution, however skewed distributions come about in many processes. The classical method to estimate process capability is not applicable for non-normal processes. In the existing methods for non-normal processes, probability density function (pdf) of the process or an estimate of it is required. Estimating pdf of the process is a hard work and resulted PCI by estimated pdf may be far from real value of it. In this paper an artificial neural network is proposed to estimate PCI for right skewed distributions without appeal to pdf of the process. The proposed neural... 

The effect of amorphous silica-alumina (ASA) with Si/Al ratios of 0.01, 0.1, 1, and 3 on the catalytic performance of chromium catalysis in the propane dehydrogenation reaction were studied. The characterization results reveal that the Si/Al ratio significantly affects the nature and dispersion of chromium species, reducibility, the surface concentration of Cr3+, and acidity. ASA catalysis with Si/Al ratios of 0.1 and 0.01 showed a remarkable increase in Cr6+ species and the lowest α-Cr2O3, which have the highest propane conversion (with initial propylene yield of 60 and 57, respectively) due to the reduction of surface monochromate Cr6+ species, which are the precursor of coordinatively... 

Forming limit diagrams (FLDs) are extensively used in industries, particularly the auto industry. The establishment of these diagrams using a predictive approach can lead to reduction in both cost and time. In the present work, Gurson-Tvergaard-Needleman (GTN), a porosity-based model, was used to predict the FLD of an interstitial-free steel via finite element simulation. Optimum values of the GTN model were obtained by applying a response surface methodology (RSM) based on central composite design. Results show that RSM is a good method for an appropriate determination of the GTN model parameters, such as initial void volume fraction, effective void volume fraction, critical void volume... 

The nonequilibrium molecular dynamics (NEMD) simulations are performed to calculation the cross drag over a nanotube located in a uniform liquid argon flow. As is known, the behavior of fluid flows in nano-scale sizes is very different from that in microscopic and macroscopic sizes. In this work, our concern is on the flow of argon molecules over a nanotube which occurs in nanoscale sizes. We calculate the cross drag enforced the nanotube at Re<10. In this regard, we use the molecular dynamics and simulate the flow of argon molecules over (6,0), (8,0) and (10,0) nanotubes. The simulations are performed at different velocities and the cross drag coefficient is computed at different Reynolds...