Sharif Digital Repository

Waveform design for target identification and classification in multiple-input multiple-output (MIMO) radar systems has been studied in several recent works. In previous works, optimal signals for an estimation algorithm are found assuming that only signal- independent noise exists. This work extends previous research by studying the case where clutter is also present. We develop a procedure to design the optimal waveform which minimizes estimation error at the output of the minimum mean squared error (MMSE) estimators in two scenarios. In the first one different transmit antennas see uncorrelated aspects of the target, and we consider the correlated target aspects in the second one.... 

Waveform design for Target identification and classification in MIMO radar systems has been studied in several recent works. While the previous works considered signal independent noise and found optimal signals for an e stimation algorithm, here we extend the results to the case where clutter is also present and then we will find the optimum waveform for several estimators differing in the assumptions on the given statistics. Several different approaches to the optimal waveform design are proposed, including minimizing the error of MMSE estimator, minimizing the maximum error of the covariance shaping least square (CSLS) estimator and minimizing the MSE error of scaled least square (SLS)... 

Waveform design for Target identification and classification in MIMO radar systems has been studied in several recent works. While the previous works considered signal independent noise and found optimal signals, here we extend the results to the case where clutter is also present and then we will find the optimum waveform for MMSE estimator. Choosing optimal waveform for MMSE estimator leads to the Semidefinite programming (SDP) problem, a convex optimization problem which can be efficiently solved through numerical methods. Explicit solution is developed for this SDP problem in two cases .In the first case, target and clutter covariance matrices are jointly diagonalizable and in the second... 

A major problem in a multiple output converter structure is the different power flow via its various outputs. This problem leads to unwanted input DC-link voltage. This paper studies full bridge based DC-DC converters with multiple outputs. The effect of power flow variation is studied and a regenerative converter topology which controls the DC-link voltage by space voltage vector modulation technique is proposed. The proposed converter has a fast response to control the DC-link voltage in an acceptable band. Simulation and experimental results are presented to verify the analytical studies. © 2018 IEEE  

Dimension reduction techniques for text documents can be used for in the preprocessing phrase of blog mining, but these techniques can be more effective if they deal with the nature of the blogs properly. In this paper we propose a novel algorithm called PostRank using shallow approach to identify theme of the blog or blog representative words in order to reduce the dimensions of blogs. PostRank uses a graph-based syntactic representation of the weblog by taking into account some structural features of weblog. At the first step it models the blog as a complete graph and assumes the theme of the blog as a query applied to a search engine like Google and each post as a search result. It tries... 

Waveform design for target identification and classification in MIMO radar systems has been studied in several recent works. While the previous works assumed that the noise was independent of the transmission signals, here we extend the results to the signal dependent noise (clutter). We consider two scenarios. In the first scenario it is assumed that different transmit antennas see uncorrelated aspects of the target. In the second scenario, we consider the correlated target. As clutter is dependent to signal, target estimation error cannot vanish only by increasing the transmission power. It can be shown that in the second scenario, MIMO radar receiver can nullify the clutter subspace.... 

Nanosecond pulsed-power generators have many applications in industries. As the rise time and fall time of conventional semiconductor switches are usually more than a few nanoseconds, it is necessary to employ special switches or new pulse generating methods to achieve nanosecond pulses. A common method for producing narrow pulse voltage waveforms is using the reverse recovery process of diodes. In this method, a super fast recovery diode is used as an opening switch in an inductor current path. A drift step recovery diode can form a rapid cut-off current front; Hence this method can be an effective solution to generate narrow pulses. This paper describes an investigation about the effect of... 

Selective oxidations of alkenes were investigated using molecular oxygen in aqueous solution under mild conditions. Colloidal gold nanoparticles are particularly versatile catalysts for oxidation reaction with exceptionally high efficiency and significant selectivity. Gold nanorods (Au NRs) exhibited a slightly enhanced activity compare to gold nanospheres  

The current study used the horizontal slices method to develop a new formulation to calculate active pressure on retaining walls. In this method, the failure wedge is assumed to be circular in cohesive-frictional soil. In addition to the formula, graphs are provided to determine the center and radius of failure without need for calculation to determine the pressure exerted on the retaining wall. A comparison of the results of the proposed method with previous methods shows that the active pressure calculated using a circular failure wedge was higher than when using a plate failure wedge; confirming the importance of the circular failure wedge. The proposed method can calculate the shear... 

Discrimination of chiral targets is generally achieved with chiral nanomaterials. However, the limited number of intrinsic chiral nanostructures as well as their complex synthesis procedure has led to the production of chirality-induced nanomaterials as alternatives. Chirality can be induced in nanomaterials by either chirality transfer or the formation of chiral assemblies. Using the latter approach, in this work, we have provided chiral supramolecular assemblies of CdTe quantum dots (QDs) from achiral starting materials. CTAB-QD assemblies showed chiroptical activities, and their orange emission in combination with the blue emission of carbon dots was utilized as a ratiometric chiral... 

TiO2 nanoparticles were synthesized by hydrothermal assisted sol-gel technique. The preparation parameters including pH value, the amount of water, titanium tetra isopropoxide content, temperature and time of hydrothermal process were investigated by Taguchi statistical experiments to determine the influence of synthesizing variables on the optimal conditions and to realize the highest degree of crystallinity or smallest crystallite size. X-ray diffraction (XRD) analysis and direct band gap energy (Eg) values, measured via diffuse reflectance spectra (DRS), proved that all the samples consist of anatase as a unique phase. Transmission electron microscopy (TEM) and specific surface area... 

Colloidal stability of dextran (Dex) and Dex/poly ethylene glycol (PEG) coated TiO2 nanoparticles (NPs) were investigated. The particles were successfully synthesized by a hydrothermal assisted sol-gel technique. The results of Ultraviolet-visible (UV-vis) spectrophotometry showed that Dex and PEG additions during hydrothermal process (HTP) led to the formation of long-term (more than 60 days) stable colloids, while the addition of dispersants after HTP did not have a significant impact on the colloidal stability of NPs. X-ray diffraction (XRD) and selected area electron diffraction (SAED) analyses proved that PEG and/or Dex coated NPs had less crystallinity than the plain TiO2. Fourier... 

Discrimination of chiral targets is generally achieved with chiral nanomaterials. However, the limited number of intrinsic chiral nanostructures as well as their complex synthesis procedure has led to the production of chirality-induced nanomaterials as alternatives. Chirality can be induced in nanomaterials by either chirality transfer or the formation of chiral assemblies. Using the latter approach, in this work, we have provided chiral supramolecular assemblies of CdTe quantum dots (QDs) from achiral starting materials. CTAB-QD assemblies showed chiroptical activities, and their orange emission in combination with the blue emission of carbon dots was utilized as a ratiometric chiral...