Sharif Digital Repository

To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular... 

This letter investigates the problem of threedimensional (3-D) target localization in multiple-input multipleoutput (MIMO) radars with distributed antennas, using hybrid timedelay (TD) and angle of arrival (AOA) measurements. We propose a closed-form positioning method based on weighted least squares (WLS) estimation. The proposed estimator is shown theoretically to achieve the Cramer-Rao lower bound (CRLB) under mild noise conditions. Numerical simulations also verify the theoretical developments. IEEE  

In this letter, the problem of target localization from bistatic range (BR) measurements in distributed multiple-input multiple-output radar systems is investigated. By introducing nuisance parameters, a pseudolinear set of BR equations is established. Then, a closed-form localization algorithm is developed, based on this pseudolinear set of equations and multistage weighted least squares estimation. This solution is shown analytically to attain the Cramer-Rao lower bound under the small Gaussian noise assumption. Simulations are included to support the theoretical studies. Unlike the existing studies where the variance of BR measurements is assumed to be independent of the corresponding... 

In this study, the authors propose an algorithm to reduce the effect of antenna location uncertainty for locating moving targets in multiple-input multiple-output (MIMO) radar systems. The proposed method is a closed-form solution which employs the measurements of multiple independent targets to alleviate the antenna location uncertainties. The authors establish a pseudo-linear set of equations by using the range and the range-rate auxiliary parameters, which allows the problem to be solved using a two-stage weighted least squares estimator. The proposed method is shown analytically and confirmed by simulations to attain the Cramer-Rao lower bound under small error conditions. The... 

The binary-valued images usually represent shapes. Therefore, the recovery of binary images from samples is often linked with recovery of shapes, where certain parametric structures are assumed on the shape. In this paper, we study the recovery of shape images with the perspective of low-rank matrix recovery. The matrix of such images is not automatically low-rank. Therefore, we consider the Hankel transformation of binary images in order to apply tools in low-rank matrix recovery. We introduce an ADMM technique for the reconstruction which is numerically confirmed to yield suitable results. We also analyze the sampling requirement of this process based on the theory of random matrices. ©... 

In this paper, we study the recovery of a certain type of shape images modeled as binary-valued images from few Fourier samples. In particular, the boundary of the shapes is assumed to be the zero level-set of a trigonometric curve. This problem was previously considered in [1], and it was shown that such images can be studied withing the framework of signals with finite rate of innovation. In particular, an annihilation filter is introduced to recover the trigonometric boundary curve. It is proved in [1] that 3Λ Fourier samples are sufficient to exactly recover the edges of a binary shape, where Λ is the bandwith of the trigonometric boundary curve. In this paper, we introduce a class of... 

In this article, we propose a software-hardware system to improve the quality of image recovery in millimeter-wave (MMW) imaging systems, which aims to benefit from copolarization and cross-polarization scatterings from the target. The proposed dual-polarized antenna array structures consist of two orthogonal subarrays with the same phase center, where each subarray is comprised of 2 imes 1 or 4 imes 1 rectangular edge fed patches and the optimized ground defects. These compact structures, which support radiation of two orthogonal linear polarizations, are designed on a single-layer board using crossover technique. The dual-polarized scattering from the target is captured by the orthogonal... 

Mud filtration happens during an overbalanced drilling operation that causes mud invasion into pores and fractures. The productivity of a formation is significantly affected by the invasion of the mud into the near-wellbore area during the mud loss process. A considerable number of studies have evaluated mud filtration statically; however, a few studies have considered the dynamic behavior of a mud loss process during overbalanced drilling, which results in the inadequate prediction of the mud loss volume and inflicted damage to the formation. In this study, a near-wellbore simulation system (NeWSS) was designed to evaluate the dynamic mud loss behavior using dimensionless parameters and... 

One of the primary factors affecting the amount of worldwide energy consumption and greenhouse gas emissions is cooking. Solar cooking is an appropriate solution because it is both inexpensive and expandable. To illustrate modern advancements and the current status of solar cooking technology, this paper presents a review of recent experimental and analytical socioeconomic studies on solar cookers. The experimental studies have been divided into three categories based on different solar cooker structures: (i) box types, (ii) concentrating types, and (iii) panel types. Next, different designs are investigated according to their direct or indirect heat transfer modes and optional equipment for...