Sharif Digital Repository

This study compares the performance of three different approaches to modeling namely the classical pore-blocking models, artificial neural networks (ANN) and the novel genetic programming (GP) approach. Among the available models proposed by Hermia, standard pore-blocking and cake filtration models were opted because of their better fitness with experimental measurements. A feedforward backpropagation network using Bayesian Regulation as well as Levenberg-Marquardt training methods was developed based on the experimental results. Network inputs include the controlling parameters of permeate flux namely: temperature, transmembrane pressure, crossflow velocity, pH, and filtration time. The... 

Emission factors (EFs) are fundamental, necessary data for air pollution research and scenario implementation. With the vision of generating national EFs of the Iranian transportation system, a portable emission measurement system (PEMS) was used to develop the basic EFs for a statistically significant sample of Iranian gasoline-fueled privately owned light duty vehicles (LDVs) operated in Tehran. A smaller sample size of the same fleet was examined by chassis dynamometer (CD) bag emission measurement tests to quantify the systematic differences between the PEMS and CD methods. The selected fleet was tested over four different routes of uphill highways, flat highways, uphill urban streets,... 

Affordable motion sensors that are recently developed for video gaming have formed a budding line of research in the field of physical rehabilitation. These sensors have been used in many task-based applications to analyze the patients' status based on their completion of assigned tasks. However, as the accuracy of such sensors is lower than that of the clinical ones, their measured data has had very limited use in quantitative motion analysis to this date. The aim of this article is to determine Kinect's ability and accuracy in calculating higher-order kinematic parameters, such as velocity and acceleration, in hand movements. Four methods, i.e. moving average, Butterworth filter, B-spline,... 

This paper presents a new procedure for determining the fracture toughness of rock-like specimens using the diametric compression test with the center-cracked horseshoe disk (CCHD) method. Using finite element analysis, a dimensionless stress intensity factor was obtained and a formula was rendered for determining mode I fracture toughness. To evaluate the accuracy of the measurement results produced by the CCHD method, fracture toughness experiments were conducted on the same rock-like material using the notched Brazilian disk (NBD) method. The CCHD tests were simulated using a two-dimensional particle flow code for validation of the experimental results, and a great agreement between the... 

The dielectric constant e of interfacial water has been predicted to be smaller than that of bulk water (e ≈ 80) because the rotational freedom of water dipoles is expected to decrease near surfaces, yet experimental evidence is lacking. We report local capacitance measurements for water confined between two atomically flat walls separated by various distances down to 1 nanometer. Our experiments reveal the presence of an interfacial layer with vanishingly small polarization such that its out-of-plane e is only ~2. The electrically dead layer is found to be two to three molecules thick. These results provide much-needed feedback for theories describing water-mediated surface interactions and... 

This paper is concerned with the stability of nonlinear Lipschitz systems subject to bounded process and measurement noises when transmission from sensor to controller is subject to distortion due to quantization. A stabilizing technique and a sufficient condition relating transmission rate to Lipschitz coefficients are presented for almost sure asymptotic bounded stability of nonlinear uncertain Lipschitz systems. In the absence of process and measurement noises, it is shown that the proposed stabilizing technique results in almost sure asymptotic stability. Computer simulations illustrate the satisfactory performance of the proposed technique for almost sure asymptotic bounded stability... 

Cascaded H-bridge converter has been utilized recently in different high-power applications due to its modular and simple structure. In order to have a balanced operation after a fault occurrence in this converter, it is necessary to detect the switch fault and its location. In this paper, a fast power-switch fault detection method is presented to identify a fault and its location. Only one voltage measurement per phase is required by this method, and the fault detection is faster compared to the existing methods. Moreover, it is suitable for implementation on an FPGA device due to the use of simple math, relational, and state machine blocks. The proposed method is verified by computer... 

This study presents a new method called FCSMM (Fuzzy Customer Satisfaction Measurement Method) for measuring individual customer satisfaction using a fuzzy inference system. The main advantage of this method is its simplification in evaluation of Customer Satisfaction Index (CSI) based on simple linguistic statements collected from experienced people. In contrast with assumptions used in other methods such as linear regression principles and predefined criteria weights, the aforementioned statements form the FCSMM computational structure. Since the drivers of satisfaction and dissatisfaction and performance indexes can be simultaneously applied, concurrent direct and indirect customer... 

Wettability alteration of rock surfaces toward gas wetting have been recognized as a practical approach for maximizing the production from the gas condensate reservoirs. Most of the reported work in this area applied the so called sessile drop contact angle measurement technique to examine the change in wetting state of a surface. However, the size-dependent wetting behavior of drop which could affect the exact determination of wettability and wettability changes was not well discussed in the previous studies. Therefore, in this work, the size dependency of contact angle for four different liquid-solid-gas systems; i.e., water-calcite-air, water-treated calcite-air (nanofluid treated... 

Power transformer partial discharge signal measurement using Radio Frequency method has advantages over IEC 60270 'apparent charge' measurement method for online monitoring due to greater immunity against external interference. However, the lack of a well-defined calibration relationship between the two methods is main disadvantage of RF method. Simultaneous measurements, using these two methods, carried out on various transformer PD source models, in laboratory, to investigate main parameters that affect the relationship of results of these two methods. In this paper, factors that influence this relationship are classified into three groups: (i) type of PD sources, (ii) transformer windings... 

In this paper, an output tracking controller is proposed for cooperative transport of a gripped load by a team of quadrotors. The proposed control law requires the measurement of only four state variables: position and yaw angle of the system. Moreover, the controller provides rejection of step and ramp external force disturbances. In addition, the control basis vectors derived via optimization facilitate the real-time determination of quadrotors' control inputs. Numerical simulations show the effectiveness of the proposed control scheme and its superiority over formerly designed controllers for such systems. © 2019 Sharif University of Technology. All rights reserved  

Previous studies have measured thoracic Range of Motion (RoM) using either skin-mounted devices or supine CT-imaging and have reported on quite different RoMs. Given the inherent shortcomings of measurements of vertebrae movements from the overlying skin, the present study aims to measure normal RoM of the thoracic spine in the sagittal plane using the upright digital radiography. Lateral radiographs of the thoracic spine were obtained from eight asymptomatic male subjects in upright standing and full forward flexion using a mobile U-arm digital radiographic system. Total (T1-T12), upper (T1-T6), and lower (T6-T12) thoracic RoMs were measured. A throughout comparison of available skin-based... 

Previous studies have measured thoracic Range of Motion (RoM) using either skin-mounted devices or supine CT-imaging and have reported on quite different RoMs. Given the inherent shortcomings of measurements of vertebrae movements from the overlying skin, the present study aims to measure normal RoM of the thoracic spine in the sagittal plane using the upright digital radiography. Lateral radiographs of the thoracic spine were obtained from eight asymptomatic male subjects in upright standing and full forward flexion using a mobile U-arm digital radiographic system. Total (T1-T12), upper (T1-T6), and lower (T6-T12) thoracic RoMs were measured. A throughout comparison of available skin-based... 

In this paper, an output tracking controller is proposed for cooperative transport of a gripped load by a team of quadrotors. The proposed control law requires the measurement of only four state variables: position and yaw angle of the system. Moreover, the controller provides rejection of step and ramp external force disturbances. In addition, the control basis vectors derived via optimization facilitate the real-time determination of quadrotors' control inputs. Numerical simulations show the effectiveness of the proposed control scheme and its superiority over formerly designed controllers for such systems. © 2019 Sharif University of Technology. All rights reserved  

Fuzzy logic is a powerful problem-solving methodology that provides a remarkably simple way to draw definite conclusions from vague, ambiguous or imprecise information. This study is a review on the possibility of developing a tool to help site managers and planners in selecting the most suitable actions for construction productivity improvement in a complex construction site, using fuzzy logic theory. Improving productivity can have a large impact on the overall construction process and consequently result in significant time and cost savings, i.e. minimizing capital cost on the construction projects. Problems associated with productivity measurement such as "lack of a standard productivity... 

In this study the effects of initial concentration of Fe(II) and Fe(III) ions as well as initial pH on the bioleaching of a low-grade sphalerite ore in a leaching column over a period of 120 days with and without bacteria were investigated. Four different modifications of medium were used as column feed solutions to investigate the effects of initial concentration of Fe(II) and Fe(III) ions on zinc extraction. The experiments were carried out using a bench-scale, column leaching reactor, which was inoculated with mesophilic iron oxidizing bacteria, Acidithiobacillus ferrooxidans, initially isolated from the Sarcheshmeh chalcopyrite concentrate (Kerman, Iran). The effluent solutions were... 

With large amounts of experimental data, modern molecular biology needs appropriate methods to deal with biological sequences. In this work, we apply a statistical method (Pearson's chi-square test) to recognize the signals appear in the whole genome of the Escherichia coli. To show the effectiveness of the method, we compare the Pearson's chi-square test with linguistic complexity on the complete genome of E. coli. The results suggest that Pearson's chi-square test is an efficient method for distinguishing genes (coding regions) form pseudogenes (noncoding regions). On the other hand, the performance of the linguistic complexity is much lower than the chi-square test method. We also use the... 

The goal of this paper is to describe a simple method for the automated data acquisition and analysis of data taken by programmable instruments. Device controls and communication method are explained and some typical illustrative examples showing the potential applications of the method in real experiments are presented. This method offers a quick and flexible way to control many instruments by using a multi-device arrangement of a stacking method in a parallel operation. The General-Purpose Interface Bus (GPIB) is used here for remote control of the devices. By using Excel and Visa interactive programs and using GPIB interface, easy communication and data transfer between instruments and a... 

A type II (eoe: extraordinary-ordinary-extraordinary) phase matching condition in a 2nd Harmonic Generation of Nd-YAG laser under a high electric field in a uniaxial KDP crystal has been measured. Type II phase matching takes place when the two mixing waves are of orthogonal polarizations (extraordinary-ordinary) and the 2nd harmonic radiation corresponds to an extraordinary wave. By applying an electric field along the X(Y) axes of the crystal, a new phase-matching angle was measured under the influence of different electric fields. The deflection angle of the SHG beam was measured as a function of the applied voltage. An optical collector will focus the 1st harmonic and a fraction of its... 

In our today's societies, many dangerous chemicals are produced and transported. Due to the vast use of chemicals, more chemical accidents are taking place with huge losses. In this study a city hazardous gas monitoring network was designed to detect the dispersion of toxic and combustible gases in the primary stages. The network could cover hazardous chemical facilities, important hazardous chemical routes, warehouses and special locations which may be the targets of terrorist attacks. The network is consisted of several local networks and a central control panel complex. Each local network has a local control panel in the center and many detectors and sounders around it at distances less...