scholarly journals Peculiarities of thermal inspection of materials with short observation time

1994 ◽  
Author(s):  
V.P. Vavilov ◽  
E. Grinzato ◽  
P.G. Bison ◽  
S. Marinetti
Keyword(s):  
Observation Time ◽  
Thermal Inspection ◽  
Short Observation Time

scholarly journals A Fast Detection Algorithm for the X-Ray Pulsar Signal

2017 ◽  
Vol 2017 ◽  
pp. 1-5 ◽  
Author(s):  
Hao Liang ◽  
Yafeng Zhan
Keyword(s):  
False Alarm ◽  
Navigation System ◽  
Detection Probability ◽  
Autonomous Navigation ◽  
Detection Algorithm ◽  
Observation Time ◽  
X Ray ◽  
Fast Detection ◽  
Simulation Results ◽  
Short Observation Time

The detection of the X-ray pulsar signal is important for the autonomous navigation system using X-ray pulsars. In the condition of short observation time and limited number of photons for detection, the noise does not obey the Gaussian distribution. This fact has been little considered extant. In this paper, the model of the X-ray pulsar signal is rebuilt as the nonhomogeneous Poisson distribution and, in the condition of a fixed false alarm rate, a fast detection algorithm based on maximizing the detection probability is proposed. Simulation results show the effectiveness of the proposed detection algorithm.

scholarly journals ISAR Signal Tracking and High-Resolution Imaging by Kalman Filtering

2021 ◽  
Vol 13 (17) ◽  
pp. 3389
Author(s):  
Pei Ye ◽  
Meng-Dao Xing ◽  
Xiang-Gen Xia ◽  
Guang-Cai Sun ◽  
Yachao Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Kalman Filtering ◽  
State Vector ◽  
Observation Time ◽  
The State ◽  
Range Resolution ◽  
Resolution Image ◽  
High Resolution Image ◽  
Reconstruction Performance ◽  
Short Observation Time

In a short observation time, after the range alignment and phase adjustment, the motion of a target can be approximated as a uniform rotation. The radar observing process can be simply described as multiplying an observation matrix on the ISAR image, which can be thought of as a linear system. It is known that the longer observation time is, the higher cross-range resolution is. In order to deal with the conflict between short observation time and high cross-range resolution, we introduce Kalman filtering (KF) into the ISAR imaging and propose a novel method to reconstruct a high-resolution image with short time observed data. As KF has excellent reconstruction performance, it leads to a good application in ISAR image reconstruction. At each observation aperture, the reconstructed image denotes the state vector in KF at the aperture time. It is corrected by a two-step KF process: prediction and update. As iteration continues, the state vector is gradually corrected to a well-focused high-resolution image. Thus, the proposed method can obtain a high-resolution image in a short observation time. Both simulated and real data are applied to demonstrate the performance of the proposed method.

scholarly journals Static Network Code Dgps Positioning vs. Carrier Phase Single Baseline Solutions for Short Observation time and Medium-Long Distances

2007 ◽  
Vol 42 (3) ◽  
pp. 167-183 ◽  
Author(s):  
M. Bakuła
Keyword(s):  
Carrier Phase ◽  
Network Code ◽  
Observation Time ◽  
Reference Station ◽  
Accuracy Estimation ◽  
Gps Positioning ◽  
Gis Applications ◽  
Code Network ◽  
Single Baseline ◽  
Short Observation Time

Static Network Code Dgps Positioning vs. Carrier Phase Single Baseline Solutions for Short Observation time and Medium-Long DistancesGPS land surveys are usually based on the results of processing GPS carrier phase data. Code or pseudorange observations due to considerations of accuracy requirements and robustness are preferred in navigation and some GIS applications. Generally, the accuracy of that positioning is in the range of about 1-2 meters or so, on average. But the main problem in code GPS positioning is to know how to estimate the real accuracy of DGPS positions. It is not such an easy process in code positioning when one reference station is used. In most commercial software, there are no values of accuracy but only positions are presented. DGPS positions without estimated errors cannot be used for surveying tasks and for most GIS applications due to the fact that every point has to be have accuracy determined. However, when we used static GPS positioning, it is well known that the accuracy is determined, both during baseline processing and next by the adjustment of a GPS network. These steps of validation with redundancy in classical static phase baseline solutions allow wide use of static or rapid static methods in the main land surveying tasks. Although these control steps are commonly used in many major surveying and engineering tasks, they are not always effective in terms of short-observation-time sessions. This paper presents a new network DGPS approach of positioning with the use of at least three reference stations. The approach concerns also valid accuracy estimation based on variance-covariance (VC) matrix in the least-squares (LS) calculations. The presented network DGPS approach has the ability of reliable accuracy estimation. Finally, network DGPS positioning is compared with static baselines solutions where five-min sessions were taken into consideration for two different rover stations. It was shown that in a short observation time of GPS positioning, code network DGPS results can give even centimetre accuracy and can be more reliable than static relative phase positioning where gross errors often happen.

Detection of viruses by electron microscopy: Increased sensitivity by direct micro-ultracentrifugation of samples

1987 ◽  
Vol 45 ◽  
pp. 908-909
Author(s):  
Alain R. Trudel ◽  
M. Trudel
Keyword(s):  
Electron Microscopy ◽  
Fold Increase ◽  
Observation Time ◽  
Clinical Samples ◽  
Maximum Speed ◽  
Viral Particles ◽  
Structural Details ◽  
Latex Spheres ◽  
Increased Sensitivity ◽  
Size Of Particles

AirfugeR (Beckman) direct ultracentrifugation of viral samples on electron microscopy grids offers a rapid way to concentrate viral particles or subunits and facilitate their detection and study. Using the A-100 fixed angle rotor (30°) with a K factor of 19 at maximum speed (95 000 rpm), samples up to 240 μl can be prepared for electron microscopy observation in a few minutes: observation time is decreased and structural details are highlighted. Using latex spheres to calculate the increase in sensitivity compared to the inverted drop procedure, we obtained a 10 to 40 fold increase in sensitivity depending on the size of particles. This technique also permits quantification of viral particles in samples if an aliquot is mixed with latex spheres of known concentration.Direct ultracentrifugation for electron microscopy can be performed on laboratory samples such as gradient or column fractions, infected cell supernatant, or on clinical samples such as urine, tears, cephalo-rachidian liquid, etc..

No effect of artificial gravity on lung function with exercise training during head-down bed rest

2015 ◽  
pp. 1-7
Author(s):  
Longxiang Su ◽  
Yinghua Guo ◽  
Yajuan Wang ◽  
Delong Wang ◽  
Changting Liu
Keyword(s):  
Lung Function ◽  
Pulse Rate ◽  
Vital Capacity ◽  
Pulmonary Ventilation ◽  
Bed Rest ◽  
Forced Expiratory Volume ◽  
Observation Time ◽  
Artificial Gravity ◽  
Postural Changes ◽  
Expiratory Flow

AbstractTo explore the effectiveness of microgravity simulated by head-down bed rest (HDBR) and artificial gravity (AG) with exercise on lung function. Twenty-four volunteers were randomly divided into control and exercise countermeasure (CM) groups for 96 h of 6° HDBR. Comparisons of pulse rate, pulse oxygen saturation (SpO2) and lung function were made between these two groups at 0, 24, 48, 72, 96 h. Compared with the sitting position, inspiratory capacity and respiratory reserve volume were significantly higher than before HDBR (0° position) (P< 0.05). Vital capacity, expiratory reserve volume, forced vital capacity, forced expiratory volume in 1 s, forced inspiratory vital capacity, forced inspiratory volume in 1 s, forced expiratory flow at 25, 50 and 75%, maximal mid-expiratory flow and peak expiratory flow were all significantly lower than those before HDBR (P< 0.05). Neither control nor CM groups showed significant differences in the pulse rate, SpO2, pulmonary volume and pulmonary ventilation function over the HDBR observation time. Postural changes can lead to variation in lung volume and ventilation function, but a HDBR model induced no changes in pulmonary function and therefore should not be used to study AG CMs.

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