HHT Based Analysis of Non Stationary Signals and Metal Structures

Hilbert-Huang Transform (HHT) is an innovative data-processing technique for analyzing non stationary and nonlinear signals. The analysis of these signals is to transform the time-domain data to frequency versus time data instead of the amplitude versus frequency.This paper investigates techniques to apply HHT for locating the instantaneous frequency in a signal. This signal processing technique helps in identifying several frequency components which are the indicators of the problems present in the system under test. This can be applied for analyzing aircrafts’ body structure, biomedical signals and seismic signals. Monitoring of civil structures such as bridges and buildings is critical for long-term operational cost and safety of aging structures. Applying HHT to these signals obtained from the various sensors placed in the vicinity of event or entity, it is possible to identify the problems

Image complexity based fMRI-BOLD visual network categorization across visual datasets using topological descriptors and deep-hybrid learning

This study proposes a new approach that investigates differences in topological characteristics of visual networks, which are constructed using fMRI BOLD time-series corresponding to visual datasets of COCO, ImageNet, and SUN. A publicly available BOLD5000 dataset is utilized that contains fMRI scans while viewing 5254 images of diverse complexities. The objective of this study is to examine how network topology differs in response to distinct visual stimuli from these visual datasets. To achieve this, 0- and 1-dimensional persistence diagrams are computed for each visual network representing COCO, ImageNet, and SUN. For extracting suitable features from topological persistence diagrams, K-means clustering is executed. The extracted K-means cluster features are fed to a novel deep-hybrid model that yields accuracy in the range of 90%-95% in classifying these visual networks. To understand vision, this type of visual network categorization across visual datasets is important as it captures differences in BOLD signals while perceiving images with different contexts and complexities. Furthermore, distinctive topological patterns of visual network associated with each dataset, as revealed from this study, could potentially lead to the development of future neuroimaging biomarkers for diagnosing visual processing disorders like visual agnosia or prosopagnosia, and tracking changes in visual cognition over time

Modified Electromagnetic Actuator for Active Suspension System

Active suspension is a type of suspension systems which can vary its damping value in order to adjust the spring firmness in accordance with the road conditions. Real Active Suspension incorporates an external actuator which helps in raising or lowering of vehicle chassis independently at each wheel. Generally, the actuators that are used for active suspension are Hydropneumatic, Electro-hydraulic or Electromagnetic actuators. A new concept of two-way electromagnetic actuation with the help of magnetic damping is proposed in this paper, which can extend its arm on both sides to facilitate active suspension mechanism in both humps and potholes. This increases the ride quality while maneuvering not only in humps, but also in dumps. It also describes about the comparison of spring materials, sophisticated design, construction and working principle of newly proposed actuator. Catia V5 software has been used to design and simulate the actuator model, different spring materials are analyzed and their shear stress and deflections are compared

Corrosion and Tribological Characteristics of FSPed Aluminum Alloy AA5052

Friction stir processing (FSP) is a solid-state and effective process for surface modification of aluminium alloys. In this study the AA5052 alloy, widely used in marine applications, has been subjected to FSP. The FSP trials have been carried out by altering the FSP process parameters (tool rotation speed, tool traverse speed, and shoulder diameter). The friction stir processed specimens have been characterised / tested for microstructure, microhardness, sliding wear, immersion corrosion, and electrochemical corrosion. The hybrid polynomial – radial basis function-based models have been developed to determine the relationship between the process parameters and the evaluated properties. Furthermore, the optimum parameters for obtaining high hardness, wear resistance, and corrosion resistance have been determined. Microstructure evaluation in the friction stir processed specimens has shown refinement and uniform dispersion of β particles throughout the α-Al matrix. The results show that the improvement in properties is a result of the homogeneous dispersion of secondary β phase particles in the matrix. Friction stir processing of AA5052 alloy has improved hardness by ~14.5%, wear resistance by ~83%, and corrosion resistance ~87%. The optimum process window for friction stir processing of AA5052 alloy is tool rotation speed between 500 rpm and 900 rpm, tool traverse speed between 10 mm/min and 30 mm/min, and tool shoulder diameter of 18 mm and 21 mm

Circuit modeling of multiband high-impedance surface absorbers in the microwave regime

In this paper, we present a simple circuit model to study the absorption of electromagnetic waves by a multilayer structure with a high impedance surface in the microwave regime. The absorber consists of a stack of two-dimensional arrays of sub-wavelength meshes or patches separated by dielectric slabs and backed by a metallic ground plane, with a single resistive sheet placed on the top layer. We observe the appearance of low-frequency resonances of total absorption, which have been identified as the resonances of Fabry-Pérot type associated with the individual reactively loaded dielectric slabs (that are strongly coupled through the subwavelength grids). It is shown that these resonances lie within certain characteristic frequency band defined by the structural parameters of the absorber. The observed resonances are characterized by studying the electromagnetic field behavior using the circuit model and full-wave numerical program. In addition, we show that the patch array absorber provides stable resonances with respect to the angle and the polarization of obliquely incident plane wavesMinisterio de Ciencia e Innovación TEC2010-16948, CSD2008-00066Junta de Andalucía TIC-459

Enhanced photocatalytic activity of N, P, co-doped carbon quantum dots: an insight from experimental and computational approach

Herein, we demonstrate the single-step microwave radiation assisted approach to develop Nitrogen (N) and Phosphorous (P) co-doped carbon quantum dots (NP-CQD). The developed NP-CQD showed enhancement in visible light photocatalytic activity towards methylene blue dye degradation than that of N-CQD and P-CQD due to creation of energy states and reduced work function as estimated by Ultraviolet photoelectron spectroscopy and corroborated by first-principles Density Functional Theory (DFT) calculations

Multi-band high-impedance surface absorbers with a single resistive sheet: Circuit theory model

We present a simple and efficient circuit model for the analysis of multi-band absorption characteristics of a stack of sub-wavelength grids (fishnets or patch arrays) in a layered environment with a single resistive sheet placed on top. It is shown that at low frequencies the resonances of total absorption occur, which are explained in terms of Fabry-Pèrot resonances associated with the individual reactively loaded dielectric slabs (that are strongly coupled through the sub-wavelength grids). It is observed that the number of absorption peaks in the absorption band corresponds to the number of reactively loaded dielectric slabs. The results of the proposed analytical model are validated with the full-wave simulations, showing good agreement

Identification of Novel SHPS-1-associated Proteins and Their Roles in Regulation of Insulin-like Growth Factor-dependent Responses in Vascular Smooth Muscle Cells

Tyrosine phosphatase non-receptor type substrate-1 (SHPS-1), a transmembrane protein, plays a vital role in cell migration and proliferation. Our previous studies have shown that insulin-like growth factor-I (IGF-I) stimulates SHPS-1 phosphorylation, leading to recruitment of SHP-2, c-Src, Shc, and Grb2·p85 to phosphorylated SHPS-1. Assembly of this signaling complex is required for optimal stimulation of both mitogen-activated protein and phosphatidylinositol 3-kinase pathways. The main aim of the present study was to identify novel proteins that interacted with the cytoplasmic domain of SHPS-1 (SHPS-1/CD) in response to IGF-I stimulation and define the role of these interactions in mediating specific biological functions. We performed a functional proteomic screening to identify SHPS-1 binding partners using combination of mRNA display and the tandem affinity purification-tag methods. Screening identified a number of proteins not previously known to interact with phosphorylated SHPS-1/CD. These novel SHPS-1 binding partners represent several functional categories including heat shock proteins, protein kinases and phosphatases, and proteins that regulate transcription or translation. In Vivo and in vitro studies suggested that most of the proteins bound to SHPS-1 via binding to one of the four SH2 domain containing proteins, SHP-2, CTK, SUPT6H, and STAT1, that directly bound to SHPS-1. Although the binding of most of these proteins to SHPS-1 was positively regulated by IGF-I, a few were negatively regulated, suggesting differential regulation of protein complexes assembled on SHPS-1/CD in response to IGF-I. Further studies showed that truncation of SHPS-1/CD significantly impaired IGF-I-dependent AKT signal transduction and subsequent biological functions including cell survival, protein synthesis, protein aggregation, and prevention of apoptosis. The results emphasize the importance of formation of SHPS-1 signaling complex induced by IGF-I and provide novel insights into our knowledge of the role of this molecular scaffold in regulation of IGF-I-stimulated signal transduction and biological actions

Enhanced transmission with a graphene-dielectric microstructure at low-terahertz frequencies

Here, we report on the transmissivity of electromagnetic waves through a stack of monolayer graphene sheets separated by dielectric slabs at low-terahertz frequencies. It is observed that the multilayer structure possesses band-gap properties and supports a series of bandpass and band-stop regions, similar to the cases of stacked metallic meshes separated by dielectric slabs at microwave/THz frequencies and a metal-dielectric stack at optical frequencies. The transmission resonances in the bandpass region are identified as coupled Fabry-Pérot resonances associated with the individual cavities of dielectric slabs loaded with graphene sheets. It is also noticed that these resonances lie within a certain characteristic frequency band, independent of the number of layers in the graphene-dielectric stack. The study is carried out using a simple analytical transfer-matrix approach or, equivalently, a circuit-theory model, resulting in the exact solution for the multiple dielectric/graphene sheet surface-conductivity model. Also, an independent verification of the observed phenomena is obtained with commercial numerical simulations.Ministerio de Ciencia e Innovación TEC2010-16948Unión Europea FEDER CSD2008-00066Junta de Andalucía TIC-459