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Author

Zachariah C. Alex

Bio: Zachariah C. Alex is an academic researcher from VIT University. The author has contributed to research in topics: Monopole antenna & Antenna measurement. The author has an hindex of 7, co-authored 60 publications receiving 298 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the effect of various layer parameters like thickness, carrier concentration, defect density, mobility, conduction band offset, etc. on the cell performance has been studied in detail.

76 citations

Journal ArticleDOI
TL;DR: An overview of clinical magnetic resonance imaging of the newborn brain and the challenges in automated tissue classification of neonatal brain MRI is provided and a complete survey of the existing segmentation methods and their salient features are presented.

75 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented the design and development of Koch fractal dipole antenna for wearable applications at 450 MHz, where common jeans cotton is used as a flexible substrate material having a dielectric constant of 1.6.
Abstract: This paper presents the design and development of Koch fractal dipole antenna for wearable applications at 450 MHz. Common jeans cotton is used as a flexible substrate material having a dielectric constant of 1.6 for the design and fabrication of the proposed antenna. Increasing the number of iterations increases the number of sections, which eventually results in 32% reduction in size. Size miniaturization is obtained using second iteration Koch geometry with the antenna bandwidth of 10%, and the return loss of �25 dB is achieved under the flat condition. The investigations are to characterize the antenna not only in flat condition, but also under different bendings and crumpling conditions. The proposed Koch fractal antenna is close to the proximity of the body, and the absorption of electromagnetic power on human body is also examined. It is found that the Specific Absorption rate (SAR) is much below a safety level of 0.119 W/kg and hence suitable for wearable applications.

29 citations

01 Jan 2012
TL;DR: A microwave imaging experimental set up using a 1-D beamforming algorithm for the detection of buried object using UWB antenna operating at 1{ 11GHz, and the experimental validation is developed.
Abstract: In this paper, we have developed a microwave imaging experimental set up using a 1-D beamforming algorithm for the detection of buried object using UWB antenna operating at 1{ 11GHz, and done the experimental validation. The experiment consists of a mechanical scanner with 3.6mm resolution in the X and Y directions, UWB horn antenna which sweeps over the frequency range. The antenna transmits the microwave signal and receives the backscatters from all the objects. These backscatters are passed through the 1-D bean former designed to image the backscatter energy as a function of location. Object of size 4mm embedded in the sand bath has been detected using the developed microwave imaging set up. 1. INTRODUCTION The studies conducted in the past have proved the potential of microwave imaging technique for many applications in the fleld of non destructive evaluation. Difierent types of microwave imaging systems are currently being used for imaging in areas such as ground penetrating radar and remote sensing. Depending on the objects and medium to be imaged, difierent antennas are needed; these range from small antennas used for near fleld measurements in ground penetrating radar to large airborne system used in remote sensing. Microwave imaging using the subsurface UWB radar technique do not attempt to reconstruct the dielectric properties proflle of the object, instead seeks to identify the presence and location of signiflcant scatterers in the medium. To create images from microwave measurements, it is necessary to construct a microwave imaging system which is able to transmit microwaves and measure the scattered waves at one or more antennas. There are two key issues to address while designing a microwave imaging system. One is the increase of the signal to noise ratio in the system and the other is to assure that the system has a large dynamic range. These are important because of the fact that the scattered signal is often weak in comparison with the transmitted signal. This implies that any noise in the system will have large impact on the image quality and then the system must be able to distinguish even small difierence in the received signals. Microwave imaging can be done in two ways. One based on analysis of the transmitted signals from the target, and another is by analyzing the scattered signals. The latter technique is used in many applications because it can be done with one antenna or both antennas at nearby distances. UWB based radar technique is used in this work to detect the embedded objects to locate the position and size In radar based techniques, the wide bandwidth is a prerequisite to achieving high fldelity of the radiated pulse. The multi-frequency approach allows for the reconstruction of the permittivity distribution with higher fldelity compared to a single frequency or narrow band reconstruction (1).

13 citations

Proceedings ArticleDOI
01 Dec 2012
TL;DR: Development of automatic voice activated low cost wheelchair using intelligent standalone controlling system and Interfaces (Embedded LabVIEW and Compact Reconfigurable Input/Output FPGA Card-cRIO-9074) for physically impaired people is presented.
Abstract: Development of automatic voice activated low cost wheelchair using intelligent standalone controlling system and Interfaces (Embedded LabVIEW and Compact Reconfigurable Input/Output FPGA Card-cRIO-9074) for physically impaired people is presented in this paper. Various interfaces to control the powered wheelchair were proposed in the past since the voice is the most natural communication ways for person so our study pays more attention to speech recognition. The voice commands produced by the user are captured and processed by the intelligent system. The system is integrated with Ultrasonic sensor and IR sensor for obstacle detection and path finding.

12 citations


Cited by
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ReportDOI
08 Dec 1998
TL;DR: In this article, the authors consider the unique features of UWB technology and propose that the FCC should consider them in considering changes to Part 15 and take into account their unique features for radar and communications uses.
Abstract: In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.

644 citations

Journal ArticleDOI
TL;DR: A fully automated processing pipeline for the structural Magnetic Resonance Imaging (MRI) of the developing neonatal brain is proposed, which has been specifically designed to address considerable differences between adult and neonatal brains, as imaged using MRI.

313 citations

Journal ArticleDOI
TL;DR: Methods adopted for the perinatal brain segmentation methods are reviewed and categorised according to the target population, structures segmented and methodology, and future directions and open challenges for research are discussed.

169 citations

Book ChapterDOI
Y. Chéron1
01 Jan 1992
TL;DR: This chapter will focus on the design of the non-reversible series resonant converter.
Abstract: After the introduction and justification of several more or less well known and complicated conversion topologies based on series resonance, this chapter will focus on the design of the non-reversible series resonant converter. Following this, a brief description will be given concerning a collection of DC/DC and DC/AC converters developed under various industrial contracts by the Laboratoire d’Electrotechnique et d’Electronique Industrielle (L.E.E.L), Toulouse, France.

157 citations

Book ChapterDOI
John W. Moore1
01 Apr 1975
TL;DR: This collection of papers given at the Colloquium on Membranes, Ions, and Impulses is dedicated to Kacy Cole and Dan Tosteson, the American Physiological Society President for 1974.
Abstract: The title of the Colloquium on Membranes, Ions, and Impulses was chosen from Cole’s book, and it is a pleasure to dedicate this collection of papers given at the Colloquium to Kacy. It is a privilege to be in the unique position of having been associated with both Kacy Cole and Dan Tosteson, our American Physiological Society President for 1974.

130 citations