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Polymer Composites for Stealth Technology
Published in Anandhan Srinivasan, Selvakumar Murugesan, Arunjunai Raj Mahendran, Progress in Polymer Research for Biomedical, Energy and Specialty Applications, 2023
Deepthi Anna David, Vidhukrishnan Naiker, Jabeen M. J. Fatima, Thomas George, Pritam V. Dhawale, Mrudul Vijay Supekar, P. M. Sabura Begum, Vijay Kumar Thakur, Prasanth Raghavan
Radio detection and ranging (RADAR), the gadget which is utilized for discovery and going of contacts, free of time and climate conditions, was perhaps the main logical revelations and innovative advancements that rose up out of WWII. Its turn of events, similar to that of most extraordinary developments, was mothered by need. Behind the advancement of radar lay over a hundred years of radio turn of events [7]. Radar is used to recognize and observe the target objects at significant distances by very short eruptions of electromagnetic radiation at the speed of light and the target object will reflect waves which are returned as a reverberation [7]. A radar framework utilizes high-velocity electromagnetic waves to decide the distance, the speed, the heading being voyaged, and the rise height of both fixed and non-fixed objects. These target objects include climate arrangements, engine vehicles, ships, airplanes, shuttles, and even landscapes [8]. Radars can be used for missile guidance (military), navigation, threat detection (military), space exploration/tracking, air traffic control, weather, battlefield, and reconnaissance [8].
Wetlands: Coastal, InSAR Mapping
Published in Yeqiao Wang, Coastal and Marine Environments, 2020
Zhong Lu, Jinwoo Kim, C. K. Shum
A synthetic aperture radar (SAR) is an advanced radar system that utilizes image-processing techniques to synthesize a large virtual antenna, which provides much higher spatial resolution than is practical using a real-aperture radar.[4] A SAR system transmits electromagnetic waves at a wavelength that can range from a few millimeters to tens of centimeters. Because a SAR actively transmits and receives signals backscattered from the target area and the radar signals with long wavelengths are mostly unaffected by weather clouds, a SAR can operate effectively during day and night under most weather conditions. Through SAR processing, both the intensity and phase of the radar signal backscattered from each ground resolution element (typically meters to submeters in size) can be calculated and combined to form a complex-valued SAR image that represents the radar reflectivity of the ground surface.[4] The intensity (or strength) of the SAR image is determined primarily by the terrain slope, surface roughness, and dielectric constant. The phase of the complex-valued SAR image is related to the apparent distance from the satellite to a ground resolution element as well as the interaction between radar waves and scatterers within a resolution element of the imaged area.
Applications of Windows
Published in K. M. M. Prabhu, Window Functions and Their Applications in Signal Processing, 2018
The term “radar” stands for radio detection and ranging. As the name suggests, the primary function of most of the radars is to find the range of certain target objects. When two or more such targets are very close, it becomes difficult to identify them as individual targets. Radar that overcomes such a difficulty is said to have good range resolution capability. In radar applications, it is desirable to have high range resolution (HRR) [1], while maintaining adequate average transmitted power (ATP). This is accomplished by a technique called pulse compression, as a part of which, either the frequency modulation (FM) or the phase modulation (PM), is employed. FM can in turn have variants that use one of the following waveforms: linear FM (LFM) waveform, frequency-modulated continuous waveform, and stepped frequency waveform (SFW). One undesirable effect of pulse compression is that side lobes appear at the output. This problem can be solved by making use of window functions. It is known from the earlier chapters that a proper choice of a window can considerably reduce the side-lobe effect. LFM pulse compression can be implemented either by correlation processing (mainly used for narrow-band and some medium-band applications) or by stretch processing (used for wideband applications). The use of SFW is known to produce HRR target profiles. We will now proceed to see how exactly windowing is used in (i) obtaining HRR target profiles and (ii) stretch processing. Furthermore, we shall illustrate the effect of different windows on pulse compression using computer simulations for various scenarios.
Application of weather Radar for operational hydrology in Canada – a review
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2021
Dayal Wijayarathne, Paulin Coulibaly
Radar is used for various applications such as military, nautical, aviation, marine, meteorology, biology, and weather surveillance. The use of Radar in weather surveillance was initiated in April 1944 with the beginning of weather observing and reporting at two Harbor Defense Cristobal installations (Best 1973; Whiton et al. 1998). Since then, the applications of weather Radar in a hydrological context have evolved significantly, especially with the advances in Radar infrastructure, computer power, data processing techniques, and hydrological and climate models (Thorndahl et al. 2017). Recently, there has been a significant focus on real-time precipitation information derived from weather Radar to complement conventional rainfall gauges since it provides real-time, spatially, and temporally continuous data over a large area (Thorndahl et al. 2017). Due to the Radar signal's ability to penetrate clouds and rain, it can be used to provide information on the internal structure of a storm (Hasler and Morris 1986). These capabilities contribute to Radar playing an essential role in meteorological studies (Doviak and Zrnić 1993). Different countries use their weather Radar systems that produce different commercial Radar products such as Radar-Online-Aneichung (RADOLAN) in Germany (Marx et al. 2006), Nimrod in the UK (Moore et al. 2004), and Next Generation Weather Radar (NEXRAD) in the USA (Krajewski et al. 2011). Those products provide a fixed Cartesian grid with rainfall accumulation data summarized over a given time period (Thorndahl et al. 2017).
Adaptive monitoring for autonomous vehicles using the HAFLoop architecture
Published in Enterprise Information Systems, 2021
Edith Zavala, Xavier Franch, Jordi Marco, Christian Berger
The last category corresponds to the Functional challenges. These challenges refer to the aspects related to the (adequate) operation of the data gathering task of the perception stage, independently from the technology, i.e. sensor data completeness/redundancy, reliability and process optimisation. For example, in high-density traffic conditions, radar systems may pick up other vehicles’ radar signals, causing false detections, interference and additional uncertainty (Hischke 1995; Schipper et al. 2015). Moreover, as more sensors are integrated into vehicles, e.g. for supporting data fusion algorithms, the risk of faults increases as well as the power consumption (Ren et al. 2018; Gawron et al. 2018). A popular approach to optimise AVs energy consumption is the adoption of V2V and V2I communications (Gawron et al. 2018; Guanetti, Kim, and Borrelli 2018); however, correctly supporting these capabilities in AVs remains still a challenge (Gruyer et al. 2017; Van Brummelen et al. 2018). In this work, we focus on the operational aspects of AVs’ monitoring systems. Therefore, our contribution regarding current AVs challenges will be on ways to address the open Functional perception challenges.
A review of microwave testing of glass fibre-reinforced polymer composites
Published in Nondestructive Testing and Evaluation, 2019
Zhen Li, Arthur Haigh, Constantinos Soutis, Andrew Gibson, Ping Wang
For SAR, a radar antenna is typically mounted on a moving platform, and the phase history of the scattered wavefront recorded varies with the vehicle position over a modest bandwidth obtained through pulsing or chirping the radar frequency [81]. For digital beam forming, radar phased-arrays are operated by creating a beam which can be electronically steered to point in different directions. However, the circuitry for phase shifting is complicated, and the system is currently not cost-effective. In microwave holography, the single-frequency 2D holography is combined with wideband 2D SAR to produce a three-dimensional (3D) representation of an object [82]. In addition, one can slice the 3D image at various depths (depending on the available signal bandwidth), creating image slices similar to those produced by X-ray computed tomography [83–85]. Inverse synthetic aperture radar (ISAR), analogous to SAR, is not discussed here, for in this method the radar is stationary and the targets are in motion [86]. This setup is not practical in many engineering applications.