Sharif Digital Repository

The challenges of water resources sustainable development are enormous. Around the globe, the increasing use of water coupled with environmental deterioration calls for sustainable development of the limited water resources. As a significant part of the world's population still lacks access to safe water and adequate sanitation, and as global urbanization continues to increase, continuous, comprehensive, coordinated and cooperative water resources management is required for the sustainable future of urban areas. The objective of this study was to assess water resources sustainable development for selected urban areas around the world. Using centralized databases of international agencies for... 

An attempt to extend helical terahertz radiation generation based on pump depletion is presented here. By considering an upward plasma density ramp, such a reasonable extension is examined to improve the results. It is claimed that the output terahertz energy is saturated which is attributed to laser pump divergence. The saturation effect is enhanced by considering suitable laser and plasma parameters. The adjustable slope of the density ramp is an important parameter for tuning terahertz generation effciency, which is restricted to the up and down limit. For the resonant excitation of terahertz radiation, the ripple wave number is suitably chosen to satisfy the phase matching condition.... 

An attempt to extend helical terahertz radiation generation based on pump depletion is presented here. By considering an upward plasma density ramp, such a reasonable extension is examined to improve the results. It is claimed that the output terahertz energy is saturated which is attributed to laser pump divergence. The saturation effect is enhanced by considering suitable laser and plasma parameters. The adjustable slope of the density ramp is an important parameter for tuning terahertz generation effciency, which is restricted to the up and down limit. For the resonant excitation of terahertz radiation, the ripple wave number is suitably chosen to satisfy the phase matching condition.... 

Infrastructure visual impact assessment based on an opinion survey and fuzzy set modeling was attempted. Photographs reflecting various transportation infrastructure and environment features were displayed to a group of transportation professionals and users. The group was asked to complete a relevant questionnaire regarding the highway infrastructure appearance acceptability of photographs. A set of visual impact descriptive variables was identified and directly measured from the photographs. Information about the descriptive variables, questionnaire responses and fuzzy set theory was used to develop membership functions of visual acceptability. More than two hundred candidate membership... 

In this paper, we exploit a fuzzy controller on a flexible bevel-tip needle to manipulate the needle's base in order to steer its tip in a preset obstacle-free and target-tracking path. Although the needle tends to follow a curvature path, spinning the needle with an extremely high rotational velocity makes it symmetric with respect to the tissue to follow a straight path. The fuzzy controller determines an appropriate spinning to generate the planned trajectory and, the closed-loop system tries to match the needle body with that trajectory. The swine's brain tissue model, extracted from an in-vitro experimental setup, is a non-homogenous, uncertain and fast-updatable network to model real... 

The photon orbital and/or spin angular-momentum absorption in absorbing plasma medium causes the circular motion of electrons and generate the azimuthal component of current density. The axial magnetic field generation due to the azimuthal component of generated current density is known as inverse Faraday effect. In this paper, the axial magnetic field generation in an absorbing plasma with ramped density by the propagation of linear polarized Laguerre-Gaussian beam is taken into consideration. It is shown that the positive slope of the initial electron density causes a considerable enhancement of self-generated axial magnetic field. The magnetic field enhancement depends on the twisted... 

This paper describes an attempt to develop congestion indices for a developing country with a limited sampling. Speed and flow rate information was collected from urban highway traffic flow videotaping in Iran. Video display provided information for traffic modeling when, similar to most of the developing nations, Iran does not have locally developed highway capacity manuals. Processing of the extracted data and traffic modeling provided free and capacity flow information for the selected freeway and principal arterial sections for the capital city of Tehran. The congestion indices were associated, in simple and logical models, with five traffic descriptive variables of travel speed, travel... 

In this study, we have proposed a novel approach to investigate the features of four subbands of 2-D wavelet transform in magnetic resonance images (MRIs) for normal and abnormal brains which defected by Multiple Sclerosis (MS). Concurrently, another method extracts different kinds of features in spatial domain. Totally, 116 features have been extracted. Before applying the algorithm, we have to use a registration method because of variety in size of brain images. All extracted features have been passed over the Principal Component Analysis (PCA) and have been pushed to an Artificial Neural Network (ANN) that is a feed-forward type. According to changing in position of defected parts of... 

This paper describes an attempt to shed some light on road safety in Asia Pacific region by characterizing and assessing its road accidents. The relevant national road accident data were extracted from centralized data sources of international agencies. Due to data incompleteness and missing values, 21 Asia Pacific countries, presenting more than half of the world's population, were selected for detailed analysis. The study database consisted of 7 variables, covering years 1980 and 1995. The univariate and multivariate statistical analyses for the selected countries showed interesting results and relations for the selected variables. Accident rates, reflecting road accident risk and... 

Roadway traffic noise pollution for the Greater Tehran Metropolitan Area (GTMA) was analyzed. The study database consisted of relevant information about the noise level, traffic, roadway and meteorological characteristics. The collected noise level information at the roadway sound level meter receptor site included equivalent noise level. The equivalent noise level at reception points along the GTMA roadways was found often in breach of noise standards  

Development of a highway congestion index on the basis of expert and user opinions with fuzzy set theory was attempted. Forty 1-min videotape segments showing different highway traffic flow conditions were displayed to a group of highway experts and users. They were asked to complete the relevant questionnaires on the existence and acceptability of congestion for each video segment display. Five congestion-descriptive variables of travel speed, travel rate, delay rate, travel rate ratio, and delay ratio were determined for each video segment. Information about the values of congestion-descriptive variables for the displayed videos, questionnaire responses, and fuzzy set theory were used to... 

The municipalities of large Iranian cities require regular air pollutant emission monitoring for motor vehicles. The recorded data include information about commonly regulated air pollutants and motor vehicle characteristics which were randomly selected and studied from the Tehran database. Regression analysis was found ineffective in modeling the relationships among air pollutant, meteorological and motor vehicle characteristics. However, the artificial neural network, ANN, modeling seem to be a useful tool for prediction of air pollutants. The developed ANN models were found to be superior to the developed regression models. Application of the study approach and results could improve motor... 

In this paper, a new approach for non-invasive diagnosis of breast diseases is tested on the region of the breast without undue influence from the background and medically unnecessary parts of the images. We applied Wavelet packet analysis on the two-dimensional histogram matrices of a large number of breast images to generate the filter banks, namely sub-images. Each of 1250 resulting sub-images are used for computation of 32 two-dimensional histogram matrices. Then informative statistical features (e.g. skewness and kurtosis) are extracted from each matrix. The independent features, using 5-fold cross-validation protocol, are considered as the input sets of supervised classification. We... 

Hydraulic fracturing is a complicated phenomenon in which deformation of the porous medium and fluid leak-off to the surrounding area take place simultaneously. Their interaction therefore must not be overlooked. Modeling of this phenomenon in isothermal conditions requires analysis of soil deformation and crack and pore fluid pressure interaction. In this paper, a numerical scheme is presented for analysis of soil stresses and deformations and fluid flow in a coupled manner. This scheme is also used to detect the fracture in the medium. Our model was used in simulating a set of hydraulic fracturing experiments. These experiments were performed on compacted hollow cylindrical specimens under... 

International trade is the backbone of our modern, commercial world, as producers in various nations try to profit from an expanded market, rather than be limited to selling within their own borders. There are many reasons that trade across national borders occurs, including lower production costs in one region versus another, specialized industries, lack or surplus of natural resources and consumer tastes. In this paper, international trade distribution is analyzed using the Asian multimodal network. This network consists of 31 countries and for the purpose of this study trade is assumed to be distributed between the capitals of the countries. The study concentrates on the Gravity model of... 

Globalization is shaping a new socio-economic order with profound, and still unfolding, implications for transportation development. A prerequisite for national competitiveness in the global market place is efficacious transportation when its recent technological advances have created an unprecedented rise in mobility and accessibility. Developments of efficient and effective transportation infrastructure and services are among the principal driving forces for the globalization process. Using international databanks, this paper describes an attempt to shed some light on national trends of globalization and transportation, and their relationships. Deploying a comparative macroscopic approach... 

In this paper, an attempt to identify and characterize minor road traffic behavior at unsignalized urban intersections in a city situated in a developing country is described. Information about the particular traffic behavior was collected using video cameras placed at 12 unsignalized intersections connecting minor to major roadways in Tehran. Stop signs and/or blinking red signals provided the stopping message at the minor approaches of the selected intersections. Relevant information about the behavior of more than 2400 vehicles was extracted from the video displays and the database records consisted of 31 variables reflecting driver, pedestrian, passenger, vehicle and intersection...