Results 71 to 80 of about 2,700,967 (284)

Using sub-aperture illumination to solve the shortspacing problem [PDF]

International Astronomical Union Colloquium, 1991
AbstractA common problem in producing interferometer maps of objects with structure on the scale-size of the primary beam is the acquisition of UV data corresponding to telescope spacings of less than one telescope diameter. One technique for solving this “short-spacing” problem is to divide the aperture of one of the telescopes into smaller sub ...
David P. Woody, Nick Z. Scoville, Lee G. Mundy   +2 more
openaire   +1 more source

Parity‐Dependent THz Harmonic Generation in Electrically Pumped Micro‐Lasers Exploiting Topological Insulator–Metamaterial Gratings

Advanced Materials, EarlyView.
Topological insulator–metamaterials integrated with electrically driven terahertz quantum cascade lasers enable parity‐dependent harmonic generation. Bulk‐dominated Bi2Se3 favors third‐harmonic emission at 9.96 THz, whereas topological‐surface‐state‐dominated Bi2Se3, Bi2Te3, and (Bi,Sb)2Te3 generate strong second harmonics near 6.5 THz.
Alessandra Di Gaspare, Craig S. Knox, Ahmet Yagmur, Sara Ghayeb Zamharir, Lianhe Li, Satoshi Sasaki, A. Giles Davies, Edmund H. Linfield, Joshua R. Freeman, Miriam S. Vitiello   +9 more
wiley   +1 more source

Highly Sensitive Broadband Photodetectors Based on Donor–Acceptor 2D Conjugated Coordination Polymers

Advanced Materials, EarlyView.
Donor–acceptor molecular design and chemical vapor deposition growth enable the two‐dimensional nickel‐tetraaminobenzoquinone films with strong broadband absorption and efficient charge separation. The resulting photodetectors exhibit a structured broadband response with a high responsivity of ∼3.1 A W−1 and a response time of ∼170 µs, which surpasses ...
Yunxu Chen, Jinxin Liu, Shuai Fu, Apurba Mahapatra, Dongxu Wang, Mike Hambsch, Angelika Wrzesińska‐Lashkova, Jing Wang, Fabian Paulus, Yana Vaynzof, Stefan C. B. Mannsfeld, Fuchun Zhang, Mischa Bonn, Renhao Dong, Xinliang Feng   +14 more
wiley   +1 more source

Precise Aperture-Dependent Motion Compensation with Frequency Domain Fast Back-Projection Algorithm

Sensors, 2017
Precise azimuth-variant motion compensation (MOCO) is an essential and difficult task for high-resolution synthetic aperture radar (SAR) imagery. In conventional post-filtering approaches, residual azimuth-variant motion errors are generally compensated ...
Man Zhang, Guanyong Wang, Lei Zhang
doaj   +1 more source

Performance Investigation on Scan-On-Receive and Adaptive Digital Beam-Forming for High-Resolution Wide-Swath Synthetic Aperture Radar [PDF]

, 2009
The work investigates the performance of the Smart Multi-Aperture Radar Technique (SMART) Synthetic Aperture Radar (SAR) system for high-resolution wide-swath imaging based on Scan-on-Receive (SCORE) algorithm for receive beam steering.
Bordoni, Federica, Younis, Marwan, Gebert, Nicolas, Krieger, Gerhard, Makhoul Varona, Eduardo   +4 more
core  

Near‐Infrared Imaging of H2O2 in Plants With Nanosensors Under Environmentally Changing Conditions

Advanced Materials, EarlyView.
This paper reports a ratiometric nanosensor enabling robust, multivariate detection of stress signals (H2O2) in plants, with high resistance to light fluctuations and mechanical disturbances. Single‐walled carbon nanotubes serve as the sensor, Egyptian Blue nanosheets serve as a stable reference, and plant autofluorescence serves as a label‐free ...
Jiaqi Li, Bjoern F. Hill, Chen Ma, Juliana Gretz, Tanuja Kistwal, Janus A. C. Wartmann, Justus T. Metternich, Juan Pablo Giraldo, Sebastian Kruss   +8 more
wiley   +1 more source

An Improved Phase Correlation Method for Obtaining Dynamic Feature of the Ocean from Sequential SAR Sub-aperture Images (in English)

Leida xuebao, 2013
Dynamic features are important aspects of the ocean. However the dynamic information is lost in most conventional Synthetic Aperture Radar (SAR) image processing methods, because they treat the image as an instantaneous state of the observed area.
Wang Xiao-qing, Sun Hai-qing, Chong Jin-song   +2 more
doaj   +1 more source

Oxygen‐Controlled Structural and Defect Engineering of Magnetron‐Sputtered ZnO Thin Films for Photosensing

Advanced Materials Interfaces, EarlyView.
Zinc oxide thin films are engineered by controlling oxygen flow and nominal partial pressure during growth to tune atomic‐scale defects and crystallographic texture that limit device performance. By balancing competing defects, the films achieve improved preferential c‐axis orientation and enhanced ultraviolet photoresponse.
Julfikar Ali Sarkar, Rupa Jeena, Mohammed Aslam   +2 more
wiley   +1 more source

Adaptive Segmented Doppler Compensation for Forward-Looking Radar Imaging

Remote Sensing
In long-aperture forward-looking radar, nonlinear Doppler mismatch caused by target relative motion can lead to positioning deviation and image defocusing.
Yingying Wang, Yongpeng Dai, Xiurong Wang, Tian Jin   +3 more
doaj   +1 more source

Aperture-Averaging - Theory and Measurements [PDF]

, 2004
Atmospheric laser communications using direct-detection systems do suffer from severe degradation caused by scintillation. Because the atmospheric cut-off frequency can be as low as 100 Hz, temporal averaging is not applicable in high-speed ...
Perlot, Nicolas, Fritzsche, Daniel
core