Scheme design and key technology verification of Narrow Angle Sensor for small body mission

2021 ◽  
Author(s):  
Fenzhi Wu ◽  
Xiao Liang ◽  
Yanpeng Wu ◽  
Yunfang Zhang ◽  
Yuan Zhao ◽  
...  
Keyword(s):  
Autonomous Navigation ◽  
Measurement Accuracy ◽  
Small Body ◽  
Spectral Observation ◽  
Detection Sensitivity ◽  
Composition Analysis ◽  
Processing Unit ◽  
Scientific Observation ◽  
Exploration Mission ◽  
Better Than

<p>   In small body exploration mission, the uncertainty of the target characteristics and the special weak gravitational environment put forward higher requirements for the optical autonomous navigation accuracy of the probe and the detection ability of the navigation sensor. Narrow Angel Sensor(Hereinafter referred to as NAS), as the key instrument of China’s first small body exploration mission, has both optical autonomous navigation function and scientific observation ability, and it must give consideration to both near and far, and achieve breakthroughs in dynamic range, detection sensitivity, pointing measurement accuracy, angular resolution and spectral observation ability. The specific performance is as follows: To capture and track Near Earth Asteroids 2016HO3 from tens of thousands of kilometers, NAS is required to have the ability of point target detection, and the detection sensitivity is better than MV10, and  the accuracy of pointing measurement is better than 1 ″. As the probe approaches the target, NAS must be able to clearly image the shape and surface texture of 2016HO3, so as to obtain the motion parameters such as the spin axis and rotation period of the target. In remote sensing and descending stage, the mission requires NAS to be able to carry out global centimeter scale and landing area millimeter scale multi-spectral observation of the target, and optical navigation uses high-resolution images to construct landmark feature library, so as to realize terrain relative navigation; meanwhile, the image is used to provide data support for the scientific research of the target topography, spectral characteristics and surface material composition analysis.</p> <p>   NAS adopts split design, and the detector part is composed of front door, baffle, focusing optical system, filter wheel, image processing circuit, and motor drive circuit, the algorithm is implemented in the image navigation processing unit. The prototype of the instruments has been developed, and the function and performances such as MTF, detection sensitivity, pointing measurement accuracy etc were verified. The instrument achieved expected design objectives,  and can meet the requirements of optical autonomous navigation and scientific observation for China’s small body exploration mission.</p>

Recent Reviews on Machine Vision-Based 3D Reconstruction

2021 ◽  
Vol 14 ◽  
Author(s):  
Hongxin Zhang ◽  
Shaowei Ma ◽  
Meng Li ◽  
Hanghang Jiang ◽  
Jiaming Li
Keyword(s):  
Machine Vision ◽  
3D Reconstruction ◽  
Autonomous Navigation ◽  
Robot Vision ◽  
Research Direction ◽  
Development Trend ◽  
Future Research ◽  
The Future ◽  
The Development Trend ◽  
Better Than

Background: In machine vision, the 3D reconstruction is widely used in medical system, autonomous navigation, aviation and remote sensing measurement, industrial automation and other fields, and the demand for reconstruction precision is significantly highlighted. Therefore, the 3D reconstruction is of great research value and will be an important research direction in the future. Objective: By reviewing the latest development and patent of 3D reconstruction, this paper provides references to researchers in related fields. Methods: Machine vision-based 3D reconstruction patents and literatures were analyzed from the aspects of the algorithm, innovation and application. Among them, there are more than 30 patents and nearly 30 literatures in the past ten years. Results: Researches on machine vision-based 3D reconstruction in recent 10 years are reviewed, and the typical characteristics were concluded. The main problems in its development were analyzed, the development trend was foreseen, and the current and future research on the productions and patents related to machine vision-based 3D reconstruction is discussed. Conclusion: The reconstruction result of binocular vision and multi-vision is better than monocular vision in most cases. Current researches of 3D reconstruction focus on robot vision navigation, intelligent vehicle environment sensing system and virtual reality. The aspects that need to be improved in the future include: improving robustness, reducing computational complexity, and reducing operating equipment requirements, and so on. Furthermore, more patents on machine vision-based 3D reconstruction also should be invented.

Research on Camera-Oriented Smart Car and Intelligent Control

2012 ◽  
Vol 260-261 ◽  
pp. 342-347
Author(s):  
Zheng Ma ◽  
Guan Bo Wang
Keyword(s):  
Intelligent Control ◽  
Autonomous Navigation ◽  
Least Squares Method ◽  
Least Square Method ◽  
Least Square ◽  
Control Algorithms ◽  
Processing Unit ◽  
Threshold Method ◽  
Central Processing ◽  
Dc Motor Control

This paper designs a camera-oriented smart car along with specialized intelligent control algorithms. MC9S12XS128 is chosen as the central processing unit and a CCD sensor along with peripheral circuit is designed as the camera module. The proposed system integrates technologies of intelligent control, Micro-Electro-Mechanism System (MEMS), System on Chip (SOC), wireless communication and low power consumption embedded technology, realizing autonomous navigation while tracking the path. In the paper, the extraction of path information is streamlined, where dynamic threshold method is used for image binarization and path optimization is done with least square method. Control algorithms are highlighted, where servo control incorporates least squares method creatively and the DC motor control, forming a closed-loop system with a rotatory encoder, adopts incremental PID control algorithm.

scholarly journals Research on Focal Length Measurement Scheme of Self-Collimating Optical Instrument Based on Double Grating

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2718
Author(s):  
Wenchang Yang ◽  
Zhiqian Wang ◽  
Chengwu Shen ◽  
Yusheng Liu ◽  
Shaojin Liu ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Focal Length ◽  
Optical Path ◽  
Good Resolution ◽  
Mean Square ◽  
Optical Instrument ◽  
Moiré Fringes ◽  
Measurement Resolution ◽  
Designed Experiment ◽  
Better Than

In this paper, we propose a scheme for measuring the focal length of a collimating optical instrument. First, a mathematical model for measuring the focal length of a collimator with double gratings is derived based on the moiré fringe formula and the principles of geometric optics. Mathematical simulation shows that a slight difference in the focal length of two collimators has an important influence on the imaging law of moiré fringes. Our solution has a good resolution ability for focal length differences within 5‰, especially in the small angle range below 4°. Thus, the focal length of collimators can be measured by the amplification of the slight difference. Further, owing to the relative reference measurement, the measurement resolution at the symmetrical position of focal length is poor. Then, in the designed experiment, a corresponding moiré image at different angles is acquired using collimators with known focal length. The experimental results indicate that the root mean square error (RMSE) of the collimator corresponding to grating angles of 2°–4° is better than 4.7‰, indicating an ideal measurement accuracy of the proposed scheme. This work demonstrates that our proposed scheme can achieve an ideal accuracy in the measurement of a symmetrical optical path.

The Pulsed Thermocouple for Gas Turbine Application

1977 ◽  
Vol 99 (1) ◽  
pp. 1-10 ◽  
Author(s):  
D. Kretschmer ◽  
J. Odgers ◽  
A. F. Schlader
Keyword(s):  
Exact Solution ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Temperature Rise ◽  
Measurement Accuracy ◽  
Gas Analysis ◽  
Gas Turbine Combustor ◽  
Analogue Circuit ◽  
Good Repeatability ◽  
Better Than

A mechanically pulsed suction thermocouple has been developed. The gas to be measured is sucked through a sonic orifice, thus eliminating the influence of the velocity inside the combustor. The signal from the thermocouple is processed by an analogue circuit. Contrary to the usual approach to the problem of dynamic temperature measurements (i.e., the attempt to find an exact solution to the extrapolation of the temperature rise curve) in this work, a calibration of the probe was done. This calibration showed very little scatter and a good repeatability. The overall measurement accuracy was better than ±1 percent. As a test of application, a partial survey of the temperature distribution within an aircraft gas turbine combustor was done. A satisfactory agreement was observed between temperatures measured by the thermocouple and those determined from gas analysis. In this test the pulse thermocouple proved to be a reliable and fast tool for the measurement of local gas temperatures.

scholarly journals GPU-accelerated alignment of bisulfite-treated short-read sequences

2017 ◽  
Author(s):  
Richard Wilton ◽  
Xin Li ◽  
Andrew P. Feinberg ◽  
Alexander S. Szalay
Keyword(s):  
Dna Sequences ◽  
Graphics Processing Unit ◽  
General Purpose ◽  
Processing Unit ◽  
Short Read ◽  
Wide Range ◽  
Programming Logic ◽  
Short Read Aligner ◽  
Graphics Processing ◽  
Better Than

AbstractThe alignment of bisulfite-treated DNA sequences (BS-seq reads) to a large genome involves a significant computational burden beyond that required to align non-bisulfite-treated reads. In the analysis of BS-seq data, this can present an important performance bottleneck that can potentially be addressed by appropriate software-engineering and algorithmic improvements. One strategy is to integrate this additional programming logic into the read-alignment implementation in a way that the software becomes amenable to optimizations that lead to both higher speed and greater sensitivity than can be achieved without this integration.We have evaluated this approach using Arioc, a short-read aligner that uses GPU (general-purpose graphics processing unit) hardware to accelerate computationally-expensive programming logic. We integrated the BS-seq computational logic into both GPU and CPU code throughout the Arioc implementation. We then carried out a read-by-read comparison of Arioc's reported alignments with the alignments reported by the most widely used BS-seq read aligners. With simulated reads, Arioc's accuracy is equal to or better than the other read aligners we evaluated. With human sequencing reads, Arioc's throughput is at least 10 times faster than existing BS-seq aligners across a wide range of sensitivity settings.The Arioc software is available at https://github.com/RWilton/Arioc. It is released under a BSD open-source license.

scholarly journals A design of forceps-type coincidence radiation detector for intraoperative LN diagnosis: clinical impact estimated from LNs data of 20 esophageal cancer patients

2021 ◽  
Author(s):  
Miwako Takahashi ◽  
Shuntaro Yoshimura ◽  
Sodai Takyu ◽  
Susumu Aikou ◽  
Yasuhiro Okumura ◽  
...  
Keyword(s):  
Esophageal Cancer ◽  
Radiation Detector ◽  
Radiation Detection ◽  
Statistical Error ◽  
Clinical Impact ◽  
Coincidence Detection ◽  
Detection Sensitivity ◽  
Scintillation Crystals ◽  
Positron Emission ◽  
Better Than

Abstract Purpose To reduce postoperative complications, intraoperative lymph node (LN) diagnosis with 18F-fluoro-2-deoxy-D-glucose (FDG) is expected to optimize the extent of LN dissection, leading to less invasive surgery. However, such a diagnostic device has not yet been realized. We proposed the concept of coincidence detection wherein a pair of scintillation crystals formed the head of the forceps. To estimate the clinical impact of this detector, we determined the cut-off value using FDG as a marker for intraoperative LN diagnosis in patients with esophageal cancer, the specifications needed for the detector, and its feasibility using numerical simulation. Methods We investigated the dataset including pathological diagnosis and radioactivity of 1073 LNs resected from 20 patients who underwent FDG-positron emission tomography followed by surgery for esophageal cancer on the same day. The specifications for the detector were determined assuming that it should measure 100 counts (less than 10% statistical error) or more within the intraoperative measurement time of 30 s. The detector sensitivity was estimated using GEANT4 simulation and the expected diagnostic ability was calculated. Results The cut-off value was 620 Bq for intraoperative LN diagnosis. The simulation study showed that the detector had a radiation detection sensitivity of 0.96%, which was better than the estimated specification needed for the detector. Among the 1035 non-metastatic LNs, 815 were below the cut-off value. Conclusion The forceps-type coincidence detector can provide sufficient sensitivity for intraoperative LN diagnosis. Approximately 80% of the prophylactic LN dissections in esophageal cancer can be avoided using this detector.

scholarly journals Comparative study of chronic energy deficiency among adult males of Andaman and Nicobar Islands and their counterparts

2018 ◽  
Vol 81 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Ramesh Sahani ◽  
Rajesh K. Gautam ◽  
Amir H. Golnabi ◽  
Neeraj Vedwan
Keyword(s):  
Indigenous People ◽  
Nutritional Assessment ◽  
Small Body ◽  
Scaling Exponent ◽  
Andaman And Nicobar Islands ◽  
Ethical Guidelines ◽  
Energy Deficiency ◽  
Chronic Energy Deficiency ◽  
Nicobar Islands ◽  
Better Than

Abstract The indigenous islanders of Andaman and Nicobar Islands are representing the earliest form of developmental stage, their nutritional assessment and anthropometric comparison with contemporary populations are the main objective of the present paper. In this study we present a cross sectional analysis of anthropometric data of 2010 individuals of 19 different groups. The data were collected by the trained anthropologists of Anthropological Survey of India, following standard techniques and ethical guidelines. It was found that the Indigenous Islanders have small body size as compared to immigrants and counterparts. The prevalence of chronic energy deficiency (CED) was found highest among the mainlanders. Highest prevalence of overweight was found among Great Andamanese (18.2%), followed by Onge (7.4%). Individuals below 21 years of age were not found to be overweight or obese. On the other side, 16.7% of individual of age 41+ of local born were found to be overweight (BMI 25.0-29.9 kg/m2). It can be concluded that the Indigenous people of the Islands are short in stature and nutritionally better than immigrants. The immigrants are better than their counterparts in the mainland, but still they are not able to reach at par of the indigenous people in the level of nutrition whereas logarithmic transformation of data and scaling exponent (β) of weight to height was found ~2 across these populations.

scholarly journals Photoacoustic hygrometer for icing wind tunnel water content measurement: design, analysis, and intercomparison

2021 ◽  
Vol 14 (3) ◽  
pp. 2477-2500
Author(s):  
Benjamin Lang ◽  
Wolfgang Breitfuss ◽  
Simon Schweighart ◽  
Philipp Breitegger ◽  
Hugo Pervier ◽  
...  
Keyword(s):  
Water Vapor ◽  
Wind Tunnel ◽  
Water Content ◽  
Measurement Accuracy ◽  
Near Infrared ◽  
Limit Of Detection ◽  
General Description ◽  
Sampling System ◽  
Content Measurement ◽  
Better Than

Abstract. This work describes the latest design, calibration and application of a near-infrared laser diode-based photoacoustic (PA) hygrometer developed for total water content measurement in simulated atmospheric freezing precipitation and high ice water content conditions with relevance in fundamental icing research, aviation testing, and certification. The single-wavelength and single-pass PA absorption cell is calibrated for molar water vapor fractions with a two-pressure humidity generator integrated into the instrument. Laboratory calibration showed an estimated measurement accuracy better than 3.3 % in the water vapor mole fraction range of 510–12 360 ppm (5 % from 250–21 200 ppm) with a theoretical limit of detection (3σ) of 3.2 ppm. The hygrometer is examined in combination with a basic isokinetic evaporator probe (IKP) and sampling system designed for icing wind tunnel applications, for which a general description of total condensed water content (CWC) measurements and uncertainties are presented. Despite the current limitation of the IKP to a hydrometeor mass flux below 90 gm-2s-1, a CWC measurement accuracy better than 20 % is achieved by the instrument above a CWC of 0.14 g m−3 in cold air (−30 ∘C) with suitable background humidity measurement. Results of a comparison to the Cranfield University IKP instrument in freezing drizzle and rain show a CWC agreement of the two instruments within 20 %, which demonstrates the potential of PA hygrometers for water content measurement in atmospheric icing conditions.

scholarly journals A High-performance Cross-platform Map Rendering Engine for Mobile Geographic Information System (GIS)

2019 ◽  
Vol 8 (10) ◽  
pp. 427
Author(s):  
Li ◽  
Wang ◽  
Guan ◽  
Xie ◽  
Huang ◽  
...  
Keyword(s):  
Operating System ◽  
Operating Systems ◽  
High Performance ◽  
Processing Unit ◽  
Performance Map ◽  
Android System ◽  
Cross Platform ◽  
Rendering Engine ◽  
Better Than ◽  
Graphics Library

With the diversification of terminal equipment and operating systems, higher requirements are placed on the rendering performance of maps. The traditional map rendering engine relies on the corresponding operating system graphics library, and there are problems such as the inability to cross the operating system, low rendering performance, and inconsistent rendering style. With the development of hardware, graphics processing unit (GPU) appears in various platforms. How to use GPU hardware to improve map rendering performance has become a critical challenge. In order to address the above problems, this study proposes a cross-platform and high-performance map rendering (Graphics Library engine, GL engine), which uses mask drawing technology and texture dictionary text rendering technology. It can be used on different hardware platforms and different operating systems based on the OpenGL graphics library. The high-performance map rendering engine maintains a consistent map rendering style on different platforms. The results of the benchmark experiments show that the performance of GL engine is 1.75 times and 1.54 times better than the general map rendering engine in the iOS system and in the Android system, respectively, and the rendering performance for vector tiles is 11.89 times and 9.52 times better than rendering in the Mapbox in the iOS system and in the Android system, respectively.

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