scholarly journals A Large-Scene Deceptive Jamming Method for Space-Borne SAR Based on Time-Delay and Frequency-Shift with Template Segmentation

2019 ◽  
Vol 12 (1) ◽  
pp. 53 ◽  
Author(s):  
Kaizhi Yang ◽  
Wei Ye ◽  
Fangfang Ma ◽  
Guojing Li ◽  
Qian Tong
Keyword(s):  
Time Delay ◽  
Frequency Shift ◽  
Processing Speed ◽  
Synthetic Aperture ◽  
Low Power Consumption ◽  
Control Factor ◽  
Correction Algorithm ◽  
Delay Term ◽  
The Past ◽  
Deceptive Jamming

Due to advantages such as its low power consumption and higher concealment, deceptive jamming against synthetic aperture radar (SAR) has received extensive attention during the past decades. However, large-scene deception jamming is still a challenge because of the huge computing burden. In this paper, we propose a new large-scene deceptive jamming algorithm. First, the time-delay and frequency-shift (TDFS) algorithm is introduced to improve the jamming processing speed. The system function of jammer (JSF) for a fake scatter is simplified to the multiplication of the scattering coefficient, a time-delay term in the range dimension and a frequency-shift term in the azimuth dimension. Then, in order to solve the problem that the effective region of the TDFS algorithm is limited, the scene deceptive jamming template is divided into several blocks according to the SAR parameters and imaging quality control factor. The JSF of each block is calculated by the TDFS algorithm and added together to achieve the large-scene jamming. Finally, the correction algorithm in squint mode is derived. The simplification and parallel-block processing could improve the calculation efficiency significantly. The simulation results verified the validity of the algorithm.

scholarly journals A Large Scene Deceptive Jamming Method for Space-Borne SAR based on Time-Delay and Frequency-Shift with Template Segmentation

2019 ◽  
Author(s):  
Kaizhi Yang ◽  
Wei Ye ◽  
Fangfang Ma ◽  
Guojing Li ◽  
Qian Tong
Keyword(s):  
Time Delay ◽  
Frequency Shift ◽  
Processing Speed ◽  
Synthetic Aperture ◽  
Low Power Consumption ◽  
Control Factor ◽  
Correction Algorithm ◽  
Delay Term ◽  
The Past ◽  
Deceptive Jamming

Due to the advantages such as low power consumption and higher concealment, deceptive jamming against synthetic aperture radar (SAR) receives extensive attention during the past decades. However, the large scene deception jamming is still a challenge because of the huge computing burden. In this paper, we propose a new large scene deceptive jamming algorithm. First, the time-delay and frequency-shift (TDFS) algorithm is introduced to improve the jamming processing speed. The system function of jammer (JSF) for a fake scatter is simplified to the multiplication of the scattering coefficient, a time-delay term in range dimension and a frequency-shift term in azimuth dimension. Then, in order to solve the problem that the effective region of the TDFS algorithm is limited, the scene deceptive jamming template is divided into several blocks according to the SAR parameters and imaging quality control factor. The JSF of each block is calculated by the TDFS algorithm and added together to achieve the large scene jamming. Finally, the correction algorithm in squint mode is derived. The simplification and parallel block processing could improve the calculation efficiency significantly. The simulation results verified the validity of the algorithm.

A Macintosh Interface for the Cameca Camebax-Micro Electron Microprobe

1990 ◽  
Vol 48 (1) ◽  
pp. 438-439
Author(s):  
Carl E. Henderson
Keyword(s):  
Electron Microprobe ◽  
Processing Speed ◽  
Word Processing ◽  
State Of The Art ◽  
Computer Control ◽  
Third Party ◽  
Disk Storage ◽  
The Past ◽  
User Facility ◽  
Instrument Control

Over the past few years it has become apparent in our multi-user facility that the computer system and software supplied in 1985 with our CAMECA CAMEBAX-MICRO electron microprobe analyzer has the greatest potential for improvement and updating of any component of the instrument. While the standard CAMECA software running on a DEC PDP-11/23+ computer under the RSX-11M operating system can perform almost any task required of the instrument, the commands are not always intuitive and can be difficult to remember for the casual user (of which our laboratory has many). Given the widespread and growing use of other microcomputers (such as PC’s and Macintoshes) by users of the microprobe, the PDP has become the “oddball” and has also fallen behind the state-of-the-art in terms of processing speed and disk storage capabilities. Upgrade paths within products available from DEC are considered to be too expensive for the benefits received. After using a Macintosh for other tasks in the laboratory, such as instrument use and billing records, word processing, and graphics display, its unique and “friendly” user interface suggested an easier-to-use system for computer control of the electron microprobe automation. Specifically a Macintosh IIx was chosen for its capacity for third-party add-on cards used in instrument control.

scholarly journals Coseismic fault-slip distribution of the 2019 Ridgecrest Mw6.4 and Mw7.1 earthquakes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yang Gao ◽  
HuRong Duan ◽  
YongZhi Zhang ◽  
JiaYing Chen ◽  
HeTing Jian ◽  
...  
Keyword(s):  
Strike Slip ◽  
Fault Slip ◽  
Slip Distribution ◽  
Synthetic Aperture ◽  
Seismic Events ◽  
Interferometric Synthetic Aperture Radar ◽  
The Past ◽  
Dextral Strike Slip Fault ◽  
Fault Slip Distribution ◽  
Dextral Strike Slip

AbstractThe 2019 Ridgecrest, California seismic sequence, including an Mw6.4 foreshock and Mw7.1 mainshock, represent the largest regional seismic events within the past 20 years. To obtain accurate coseismic fault-slip distribution, we used precise positioning data of small earthquakes from January 2019 to October 2020 to determine the dip parameters of the eight fault geometry, and used the Interferometric Synthetic Aperture Radar (InSAR) data processed by Xu et al. (Seismol Res Lett 91(4):1979–1985, 2020) at UCSD to constrain inversion of the fault-slip distribution of both earthquakes. The results showed that all faults were sinistral strike-slips with minor dip-slip components, exception for dextral strike-slip fault F2. Fault-slip mainly occurred at depths of 0–12 km, with a maximum slip of 3.0 m. The F1 fault contained two slip peaks located at 2 km of fault S4 and 6 km of fault S5 depth, the latter being located directly above the Mw7.1hypocenter. Two slip peaks with maximum slip of 1.5 m located 8 and 20 km from the SW endpoint of the F2 fault were also identified, and the latter corresponds to the Mw6.4 earthquake. We also analyzed the influence of different inversion parameters on the fault slip distribution, and found that the slip momentum smoothing condition was more suitable for the inversion of the earthquakes slip distribution than the stress-drop smoothing condition.

scholarly journals Cardiorespiratory Functioning in Youth with Persistent Post-Concussion Symptoms: A Pilot Study

2021 ◽  
Vol 10 (4) ◽  
pp. 561
Author(s):  
Aliyah Snyder ◽  
Christopher Sheridan ◽  
Alexandra Tanner ◽  
Kevin Bickart ◽  
Molly Sullan ◽  
...  
Keyword(s):  
Processing Speed ◽  
Mean Value ◽  
Exhaled Breath ◽  
Post Injury ◽  
The Past ◽  
Neurobehavioral Outcomes ◽  
End Tidal ◽  
Relationship Of ◽  
The Relationship ◽  
End Tidal Co2

Dysregulation of the autonomic nervous system (ANS) may play an important role in the development and maintenance of persistent post-concussive symptoms (PPCS). Post-injury breathing dysfunction, which is influenced by the ANS, has not been well-studied in youth. This study evaluated cardiorespiratory functioning at baseline in youth patients with PPCS and examined the relationship of cardiorespiratory variables with neurobehavioral outcomes. Participants were between the ages of 13–25 in two groups: (1) Patients with PPCS (concussion within the past 2–16 months; n = 13) and (2) non-injured controls (n = 12). Capnometry was used to obtain end-tidal CO2 (EtCO2), oxygen saturation (SaO2), respiration rate (RR), and pulse rate (PR) at seated rest. PPCS participants exhibited a reduced mean value of EtCO2 in exhaled breath (M = 36.3 mmHg, SD = 2.86 mmHg) and an altered inter-correlation between EtCO2 and RR compared to controls. Neurobehavioral outcomes including depression, severity of self-reported concussion symptoms, cognitive catastrophizing, and psychomotor processing speed were correlated with cardiorespiratory variables when the groups were combined. Overall, results from this study suggest that breathing dynamics may be altered in youth with PPCS and that cardiorespiratory outcomes could be related to a dimension of neurobehavioral outcomes associated with poorer recovery from concussion.

Frequency Shift in Drilling due to Margin Engagement

2005 ◽  
Vol 127 (2) ◽  
pp. 271-276 ◽  
Author(s):  
D. N. Dilley ◽  
D. A. Stephenson ◽  
P. V. Bayly ◽  
A. J. Schaut
Keyword(s):  
Frequency Shift ◽  
Three Dimensional ◽  
Hole Drilling ◽  
Frequency Increase ◽  
Element Analysis ◽  
Pilot Hole ◽  
Frequency Matching ◽  
The Past ◽  
Chatter Prediction ◽  
Embedded Model

Drill chatter degrades hole roundness, hole size, and tool life. This wastes time and money in tools, scrap, and hole rework. Chatter prediction in milling and turning has shown significant benefit to industry; however, researchers have been unable to accurately predict chatter in drilling applications. In the past, the drill, including the chisel edge, was modeled as either a fixed-fixed or fixed-pinned beam (Tekinalp, O., and Ulsoy, A. G., 1989, “Modeling and Finite Element Analysis of Drill Bit Vibrations,” ASME J. Eng. Indust. 111, pp. 148–154), but more recent research (Dilley, D. N., Bayly, P. V., and Schaut, A. J., 2005, “Effects of the Chisel Edge on the Chatter Frequency in Drilling,” J. Sound Vib., 281, pp. 423–428) has shown that a fixed-embedded model using springs improves frequency matching. The effects of the drill margins on dynamics have not been studied. The fixed-fixed or fixed-pinned model will be shown to be inappropriate for modeling the effects of margin engagement, while the spring-end boundary condition can better approximate the frequency increase observed experimentally as the drill margins engage deeper into the hole. In addition, the shifted frequency is well below the frequency found from an analytical fixed-fixed or fixed-pinned beam. Evidence that the margins cause the frequency shift is seen in three-dimensional waterfall plots that show this shift for pilot hole drilling (in which the margins are engaged), but not for tube drilling (in which margins are not engaged).

scholarly journals Deceptive Jamming Detection for SAR Based on Cross-Track Interferometry

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2265 ◽  
Author(s):  
Qingqing Feng ◽  
Huaping Xu ◽  
Zhefeng Wu ◽  
Wei Liu
Keyword(s):  
Sar Interferometry ◽  
Synthetic Aperture ◽  
Sar Image ◽  
Frequency Detection ◽  
Interferometric Phase ◽  
Deceptive Jamming ◽  
Jamming Detection ◽  
Novel Method ◽  
The Difference ◽  
Cross Track

Deceptive jamming against synthetic aperture radar (SAR) can create false targets or deceptive scenes in the image effectively. Based on the difference in interferometric phase between the target and deceptive jamming signals, a novel method for detecting deceptive jamming using cross-track interferometry is proposed, where the echoes with deceptive jamming are received by two SAR antennas simultaneously and the false targets are identified through SAR interferometry. Since the derived false phase is close to a constant in interferogram, it is extracted through phase filtering and frequency detection. Finally, the false targets in the SAR image are obtained according to the detected false part in the interferogram. The effectiveness of the proposed method is validated by simulation results based on the TanDEM-X system.

Multiple Sclerosis and Cognitive Impairment

2021 ◽  
pp. 39-41
Author(s):  
Cristina Valencia-Sanchez ◽  
Jonathan L. Carter
Keyword(s):  
Magnetic Resonance Imaging ◽  
Multiple Sclerosis ◽  
Cognitive Impairment ◽  
Information Processing ◽  
Magnetic Resonance ◽  
Processing Speed ◽  
Rehabilitation Program ◽  
Resonance Imaging ◽  
The Past ◽  
Demyelinating Lesions

A 60-year-old woman with a history of multiple sclerosis was evaluated for cognitive concerns. At age 30 years she had an episode of optic neuritis, followed by an episode of bilateral lower extremity numbness at age 35 years. In the following years, she had at least 6 further multiple sclerosis relapses, the last one approximately 3 years before the current presentation. She was initially treated with interferon, but she did not tolerate it. She had been taking glatiramer acetate for the past 3 years. She had noticed progressive deterioration of her gait for the past 3 years, having to use a cane on occasions. Magnetic resonance imaging of the brain showed multiple demyelinating lesions), and magnetic resonance imaging of the cervical spine showed 1 small demyelinating lesion at C6. Vitamin B12 level and thyroid function were normal. Comprehensive neuropsychological testing showed multidomain cognitive impairment, mainly impairment of speed of information processing, spatial discrimination skills, and attention/concentration. The patient’s multiple sclerosis phenotype was consistent with secondary progressive multiple sclerosis. Her cognitive impairment profile, mainly affecting information processing speed and disinhibition suggestive of frontal dysfunction, was consistent with multiple sclerosis. The patient began a cognitive rehabilitation program, and learning and memory aids were recommended. Lifestyle changes were also recommended, including weight loss and physical exercise. She was given recommendations for sleep hygiene and began taking gabapentin for neuropathic pain and restless legs. Cognitive impairment is common in patients with multiple sclerosis. Slowed cognitive processing speed and episodic memory decline are the most common cognitive deficits in MS, with additional difficulties in executive function, verbal fluency, and visuospatial analysis.

Fault detection of discrete-time delay Markovian jump systems with delay term modes partially available

2019 ◽  
Vol 356 (5) ◽  
pp. 3045-3071 ◽  
Author(s):  
Guoliang Wang ◽  
Zhiqiang Li ◽  
Xin Miao ◽  
Qingling Zhang ◽  
Chunyu Yang
Keyword(s):  
Time Delay ◽  
Fault Detection ◽  
Discrete Time ◽  
Markovian Jump Systems ◽  
Markovian Jump ◽  
Delay Term ◽  
Discrete Time Delay ◽  
Jump Systems

scholarly journals Improved global stability condition analysis for time-delay fast active queue management scalable transmission control protocol

2019 ◽  
Vol 15 (5) ◽  
pp. 155014771985193
Author(s):  
Jinfeng Huang ◽  
Lingjing Zeng ◽  
Xiaolong Chen
Keyword(s):  
Time Delay ◽  
Global Stability ◽  
Transmission Control Protocol ◽  
Active Queue Management ◽  
Maximum Growth ◽  
Stability Conditions ◽  
Queue Management ◽  
Transmission Control ◽  
Delay Term ◽  
Control Protocol

The nonlinear time-delay fast active queue management scalable transmission control protocol model was studied in this article. By analyzing the boundedness properties for solution trajectory of the fast active queue management scalable transmission control protocol model, the iterative relations of fast active queue management scalable transmission control protocol trajectory bounds were obtained. Furthermore, we calculated the maximum growth direction of the delay term in the integral interval and applied the backward method to calculate the lower conservative bound corresponding to each time of the delay term. Therefore, the global stability parameter condition of fast active queue management scalable transmission control protocol, which was less conservative than the existing global stability conditions, was obtained in this article. The validity of the stability conditions obtained in this article was verified by NS-2 simulation experiment.

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