Sharif Digital Repository

HF radar systems are widely used for the measurement of ocean surface currents and wave parameters. Theoretical analysis of high frequency radio wave backscattering from the sea has been derived in the past. Also, the relationship between Bragg frequencies and surface currents is determined and has been proved by HF radars. It is known that when surface currents are present, the Bragg frequencies move to new frequencies. Their movement is proportional to the surface current in the direction toward radar. In addition, it is observed that sea surface current changes the second order part of the spectrum of radar reflection from the sea surface. In this paper, a theoretical analysis of... 

Fragile data hiding has been extensively used for secure transmission of the sensitive data using cover images, audios and videos. In the past decade, increasingly the remote sensing applications require transmission and archiving of large number of aerial images and videos. Storage and processing of remote sensing data in the public cloud computing and storage platforms, with servers outside the control of the data owners, requires sufficient attention to persevering the privacy of the data. Furthermore, in the past few years the applications of drones and unmanned aerial vehicles demand algorithms designed especially for low altitude remote sensing data. In this paper, a novel fragile data... 

Fragile data hiding has been extensively used for secure transmission of the sensitive data using cover images, audios and videos. In the past decade, increasingly the remote sensing applications require transmission and archiving of large number of aerial images and videos. Storage and processing of remote sensing data in the public cloud computing and storage platforms, with servers outside the control of the data owners, requires sufficient attention to persevering the privacy of the data. Furthermore, in the past few years the applications of drones and unmanned aerial vehicles demand algorithms designed especially for low altitude remote sensing data. In this paper, a novel fragile data... 

Some fundamental and unique characteristics of space are (1) global perspective, (2) above the atmosphere, (3) gravity-free environment, (4) abundant resources, and (5) exploration of space itself. If the mission doesn't rely on some fundamental and unique characteristics of space, it will likely cost more to do in space than in air or on Earth [1]. On the other hand, design of complex systems like satellites involves selecting design parameters (DPs) to satisfy the required constraints while meeting desired performance objectives. These parameters are often coupled, and their relationships not easily understood, and it makes the design an iterative process with high complexity [2]. But in... 

Remote sensing satellites propulsion subsystem preliminary design based on performance sizing is discussed. The process is a fairly complicated one considering a variety of operational as well as performance requirements. This research aims to reduce the number of iterations required by the current practice to reach a compromise. It is based on a rapid-sizing method that helps lessen lengthy iteration cycles. The proposed technique, similar to such class of preliminary design processes, leads to an acceptable approximation that must be properly conveyed to other disciplines involved for further elaborations. With proper selection of design and performance parameters together with fundamental... 

Remote sensing satellites propulsion subsystem preliminary design based on performance sizing is discussed. The process is a fairly complicated one considering a variety of operational as well as performance requirements. This research aims to reduce the number of iterations required by the current practice to reach a compromise. It is based on a rapid-sizing method that helps lessen lengthy iteration cycles. The proposed technique, similar to such class of preliminary design processes, leads to an acceptable approximation that must be properly conveyed to other disciplines involved for further elaborations. With proper selection of design and performance parameters together with fundamental... 

A new method for the far field pattern synthesis of parabolic reflector antennas that can virtually optimize all major design parameters simultaneously is presented. This method optimizes the gain and the cross-polarization of the radiation pattern of the reflector antenna. It also satisfies the FCC standard limits on the sidelobe level envelope  

This paper presents a novel and fast method to distinguish regular and irregular regions in satellite and aerial images. This can be employed in further processing such as detecting man-made or artificial structures, disaster response, road sign detection and etc. In order to achieve this goal, we offer a suitable definition of regular shapes. Using this definition, we propose an appropriate technique to evaluate regularity .In our approach, discrete Fourier transform plays the main role for searching the regularity. We suggest a criterion; called RCNR, which indicates to some extent that the shape is regular. The computed RCNR value should be compared with a pre-assigned threshold value for... 

This paper introduces a new dimension reduction (DR) method, called minimum change rate deviation (MCRD), which is applicable to the DR of remote sensing images. As the main shortcoming of the well-known principal component analysis (PCA) method is that it does not consider the spatial relation among image points, our proposed approach takes into account the spatial relation among neighboring image pixels while preserving all useful properties of PCA. These include uncorrelatedness property in resulted components and the decrease of error with the increasing of the number of selected components. Our proposed method can be considered as a generalization of PCA and, under certain conditions,... 

A new and general frameworkcalled modified polynomial regression (MPR)is introduced in this letter, which detects the changes that occurred in remote sensing images. It is an improvement of the conventional polynomial regression (CPR) method. Most change detection (CD) methods, including CPR, do not consider the spatial relations among image pixels. To improve CPR, our proposed framework incorporates the spatial information into the CD process by using linear spatial-oriented image operators. It is proved that MPR preserves the affine invariance property of CPR. A realization of MPR is proposed, which employs the image derivatives to account for spatiality. Experimental results show the... 

Among the various techniques of electronic warfare in the sea, chaff has particular importance due to its easy application and its impact on the victim radar. Despite the great history of chaff, the significant research has not been published on its recognition. It is difficult to study the behavior of chaff because of the impossibility of chaff tests in an unechoic chamber. Therefore simulation would be a suitable alternative. In this paper, the simulations of symmetric feature of chaff and target are presented and it is used to propose a processing structure, based on various classifiers, for discrimination between chaff and target. Moreover the comparison between discrimination capability... 

Analysis of the multispectral remotely sensed images of the areas destroyed by an earthquake is proved to be a helpful tool for destruction assessments. The performance of such methods is highly dependant on the preprocess that registers the two shots before and after an event. In this paper, we propose a new fast and reliable change detection method for remotely sensed images and analyze its performance. The experimental results show the efficiency of the proposed algorithm. Copyright © 2006 Hindawi Publishing Corporation. All right reserved  

The rapid changes of the climate and the environment requires smart solutions and deployment of intelligent automated systems in agriculture and environment management. Rural communities should use artificial intelligence and big data analytics solutions in order to be able to mitigate the effects of climate change in the next decades. The Eco-Cyber-Physical-System (ecoCystem) is a combination of the living entities of the ecosystem in conjunction with the Cyber-Physical System (CPS) based components of the smart rural environments, interacting as a system. The goal of the ecoCystem is to use the power of artificial intelligence combined with Internet of Things (IOT) in order to provide... 

In this paper, we used echo state networks - a class of recurrent neural networks - for prediction of drought based on remote sensing data. To this end, the drought index was obtained for a number of stations in different clime zones of Iran. For each station, we also extracted the corresponding vegetation indices based on satellite imagery. Our model takes the satellite-based features as input and outputs the severity of drought. One of the major challenges of echo state networks is optimization of the reservoir parameters. Here we used a method based on Kronecker product in order to substantially reduce the parameter space to be optimized. We then used various optimization techniques... 

Urmia Lake is a large hyper-saline lake located in the northwest of Iran. It plays an important role in the hydrology, climate and ecology of its surrounding regions. In recent years, the water level of Urmia Lake has been dropped significantly. This study investigates the seasonal and annual variations of the lake area from 2000 to 2011 using remote sensing data. MODIS imageries of Normalized Differential Vegetation Index (NDVI) were used to extract the water surface area of the lake. Results reveal a significant decline in the lake area during the last past 12 years. Analysis of the seasonal images shows that maximum and minimum areas of Urmia Lake usually occur in winter and autumn,... 

A new and efficient dimension reduction method is introduced in this paper. The proposed method, almost the same as the well-known principal component analysis (PCA) method, enjoys the properties of uncorrelatedness of resulting components and orthogonality of transform coefficients. In addition, by incorporating spatial and spectral properties among image pixels, the method obtains more accurate classification results with less computational cost  

Attitude Determination (AD) is one of the key requirements of many current and emerging remote sensing missions. As such AD has been traditionally accomplished through a variety of algorithms and measurement models pertinent to sensing mechanisms. The current paper addresses conceptual validation and utility of a novel radiation based heat (measurement) model for space application. The proposed new Heat Attitude (HA) model utilizes temperature data to relate the Satellite Surfaces’ (SS) Net Heat Flux (NHF) to attitude assuming that the satellite navigational data are available. As Sun and the Earth are considered the main external sources of radiation, their effects are modeled for the SS... 

Satellite remote sensing products of AOD from MODIS along with appropriate meteorological parameters were used to develop statistical models and estimate ground-level PM10. Most of previous studies obtained meteorological data from synoptic weather stations, with rather sparse spatial distribution, and used it along with 10 km AOD product to develop statistical models, applicable for PM variations in regional scale (resolution of ≥10 km). In the current study, meteorological parameters were simulated with 3 km resolution using WRF model and used along with the rather new 3 km AOD product (launched in 2014). The resulting PM statistical models were assessed for a polluted and largely variable...