Advanced design of large scale microwave devices for space applications using space mapping optimization

Author(s):  
M. A. Ismail ◽  
Ming Yu
2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Corey J. Cochrane ◽  
Jordana Blacksberg ◽  
Mark A. Anders ◽  
Patrick M. Lenahan

Abstract Magnetometers are essential for scientific investigation of planetary bodies and are therefore ubiquitous on missions in space. Fluxgate and optically pumped atomic gas based magnetometers are typically flown because of their proven performance, reliability, and ability to adhere to the strict requirements associated with space missions. However, their complexity, size, and cost prevent their applicability in smaller missions involving cubesats. Conventional solid-state based magnetometers pose a viable solution, though many are prone to radiation damage and plagued with temperature instabilities. In this work, we report on the development of a new self-calibrating, solid-state based magnetometer which measures magnetic field induced changes in current within a SiC pn junction caused by the interaction of external magnetic fields with the atomic scale defects intrinsic to the semiconductor. Unlike heritage designs, the magnetometer does not require inductive sensing elements, high frequency radio, and/or optical circuitry and can be made significantly more compact and lightweight, thus enabling missions leveraging swarms of cubesats capable of science returns not possible with a single large-scale satellite. Additionally, the robustness of the SiC semiconductor allows for operation in extreme conditions such as the hot Venusian surface and the high radiation environment of the Jovian system.


2019 ◽  
Vol 6 ◽  
pp. 8 ◽  
Author(s):  
Wei-Bing Lu ◽  
Hui Chen ◽  
Zhen-Guo Liu

As a two-dimension planar material with zero-gap structure, graphene has a lot of outstanding properties in microwave frequency band, and the chemical vapor deposition (CVD) method can produce the large-scale graphene sheets with high quality for applications. Thus, the study about the microwave devices based on CVD-grown graphene has been aroused wide interests in the past few years. In this paper, mainly concentrating on the research by Chinese scientific groups, we review the development of microwave devices based on the CVD-grown graphene which are all validated by experiments, including attenuators, absorbers, antennas, electromagnetic interference (EMI) shielding and beam reconfiguration.


2021 ◽  
Author(s):  
Nailiang Zhuang ◽  
Chenhao Yang ◽  
Yiqi Zhao ◽  
Yongnian Song ◽  
Xiaobin Tang

Abstract With the increasing demands of versatile and long-lasting requirements of deep space missions, space nuclear reactor (SNR) power system is becoming the most potential energy source compared to conventional solar-battery and chemical energy in the future large-scale and long-life space missions. Since the very first successful launch of SNR system (SNAP-10A) in 1965, the United States, the Soviet Union / Russia, the European Union, Japan, Brazil and China have proposed various technical routes and schemes for SNR technologies over the past few decades. This paper presents a historical review of several key technologies (i.e., space nuclear reactor system and thermoelectric conversion system), especially focus on technical progress for recent decade and discusses on-going development activities. The paper also presents a forecast of potential future space applications of these key technologies.


2022 ◽  
Vol 3 (1) ◽  
pp. 1-15
Author(s):  
Divya Jyothi Gaddipati ◽  
Jayanthi Sivaswamy

Early detection and treatment of glaucoma is of interest as it is a chronic eye disease leading to an irreversible loss of vision. Existing automated systems rely largely on fundus images for assessment of glaucoma due to their fast acquisition and cost-effectiveness. Optical Coherence Tomographic ( OCT ) images provide vital and unambiguous information about nerve fiber loss and optic cup morphology, which are essential for disease assessment. However, the high cost of OCT is a deterrent for deployment in screening at large scale. In this article, we present a novel CAD solution wherein both OCT and fundus modality images are leveraged to learn a model that can perform a mapping of fundus to OCT feature space. We show how this model can be subsequently used to detect glaucoma given an image from only one modality (fundus). The proposed model has been validated extensively on four public andtwo private datasets. It attained an AUC/Sensitivity value of 0.9429/0.9044 on a diverse set of 568 images, which is superior to the figures obtained by a model that is trained only on fundus features. Cross-validation was also done on nearly 1,600 images drawn from a private (OD-centric) and a public (macula-centric) dataset and the proposed model was found to outperform the state-of-the-art method by 8% (public) to 18% (private). Thus, we conclude that fundus to OCT feature space mapping is an attractive option for glaucoma detection.


Author(s):  
David J. Chappell ◽  
Gregor Tanner ◽  
Dominik Löchel ◽  
Niels Søndergaard

Energy distributions of high-frequency linear wave fields are often modelled in terms of flow or transport equations with ray dynamics given by a Hamiltonian vector field in phase space. Applications arise in underwater and room acoustics, vibroacoustics, seismology, electromagnetics and quantum mechanics. Related flow problems based on general conservation laws are used, for example, in weather forecasting or in molecular dynamics simulations. Solutions to these flow equations are often large-scale, complex and high-dimensional, leading to formidable challenges for numerical approximation methods. This paper presents an efficient and widely applicable method, called discrete flow mapping , for solving such problems on triangulated surfaces. An application in structural dynamics, determining the vibroacoustic response of a cast aluminium car body component, is presented.


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