Instrument Modeling Concepts for Tradespace Analysis of Satellite Constellations

Constellations are gaining popularity in government and commercial space-based missions for Earth Observation (EO) due to their risk tolerance and ability to improve observation sampling in space and time. NASA Goddard Space Flight Center (GSFC) is developing a pre-Phase A tool called Tradespace Analysis Tool for Constellations (TAT-C) to initiate constellation mission design. The tool will allow users to explore the tradespace between various performance, cost and risk metrics (as a function of their science mission) and select Pareto optimal architectures that meet their requirements. This paper will describe the concept of modeling the primary science instruments within TAT-C, using a radar as an example, but extendable to imagers, occulters and lidars. The modularity of TAT-C's software architecture allows for crisply defining the interface between TAT-C's user defined or internal variables and the payload variables. The described module will inform TAT-C users of payload-dependent performance differences among thousands of constellation architectures (e.g. revisit time of the sensor swath, differential signal to noise ratio (SNR), spatial resolution of measurements) and allow them to pick an appropriate constellation architecture for detailed development. The module may also inform operational decisions of satellite modes, based on ground optimization or onboard autonomy

小型衛星搭載の合成開口レーダー用の集中型送受信システムを有する２偏波対応進行波型アンテナ

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 齋藤 宏文, 東京大学教授 橋本 樹明, 東京大学教授 保立 和夫, 東京電機大学教授 小林 岳彦, 東京工業大学教授 廣川 二郎University of Tokyo(東京大学

Design of an optimal multi-layer neural network for eigenfaces based face recognition

Face recognition is one of the most popular problems in the field of image analysis. In this paper, we discuss the design of an optimal multi-layer neural network for the task of face recognition. There are many issues while designing the neural network like number of nodes in input layer, output layer and hidden layer(s), setting the values of learning rate and momentum, updating of weights. Lastly, the criteria for evaluating the performance of the neural network and stopping the learning are to be decided. We discuss all these design issues in the light of the eigenfaces based face recognition. We report the effects of variations of these parameters on number of training cycles required to get optimal results. We also list the optimized values for these parameters. In our experiments, we use two face databases namely ORL and UMIST. These databases are used to construct the eigenfaces. The original faces are reconstructed using the top eigenfaces. The factors used in the reconstruction of the faces are used as the inputs to the neural network

Lossless gray image compression using logic minimization

A novel approach for the lossless compression of gray images is presented. A prediction process is performed followed by the mapping of prediction residuals. The prediction residuals are then split into bit–planes. Two-dimensional (2D) differencing operation is applied to bit-planes prior to segmentation and classification. Performing an Exclusive-OR logic operation between neighboring pixels in the bit planes creates the difference image. The difference image can be coded more efficiently than the original image whenever the average run length of black pixels in the original image is greater than two. The 2d difference bit-plane is divided in to windows or block of size 16*16 pixels. The segmented 2d difference image is partitioned in to non-overlapping rectangular regions of all white and mixed 16*16 blocks. Each partitioned block is transformed in to Boolean switching function in cubical form, treating the pixel values as a output of the function. Minimizing these switching functions using Quine- McCluskey minimization algorithm performs compression

Behavioural disorders amongst children of a rural community of Lucknow, India

Background: Behavioural disturbances are notable child health problem, the importance of which is increasingly recognized in most countries. A behaviour problem is nothing but a deviation from the accepted pattern of behavior on the part of the child when he is exposed to an inconsistent social and cultural environment. Aims & Objectives: To assess the prevalence of behavioural disorders in children of a rural community. Material & Methods: This was a village based cross-sectional study done among the children for the assessing the behavioural disorders. Results: Of the total 1157 children studied, 195 (16.9%) showed one or the other behavioural disorders. Various disorders elicited were bed wetting (11.6%), thumb sucking (3.1%), nail biting (1.6%) and food fad (0.5%). The disorders were more common in preschool children (34.2%) compared to school going age children (11.0%). Behavioural disorders were more frequent in children at extremes of birth orders (birth orders I & V) compared to others. The prevalence of disorders did not differ much in boys (16.2%) and girls (17.6%). Conclusions: The present study has reported a relatively higher prevalence of behavior disorders (16.9%) in children in a rural setting. The pattern of behavior problems was studied in terms of age, sex and birth order. In such children, there is a need for health education and counseling by psychiatrist/psychiatric social worker at the primary care level and must be worked ou

Development Status of Compact X-band Synthetic Aperture Radar Compatible with a100kg-class SAR Satellite and Its Future Plan

We have proposed a novel SAR system compatible with a 100kg-class small satellite. This SAR development is funded for four years (2016-2019) by Japanese government. At present we are developing engineering model (EM). This paper describes the EM test preliminary results and the future plan. The specifications of SAR observation are single polarization SAR with 1m ground resolution at minimum. A size of the satellite is 0.7m x 0.7m x 0.7m on a rocket. A size of the deployed antenna is 4.9m x 0.7m. Novel parallel-plate slotted array antennas made of honeycomb panel have been developed. Six outputs from GaN HEMT power amplifiers are combined in a waveguide resonator and 1 kW RF transmitting power is fed to the antenna trough non-contact choke flanges at deployable hinges (patented)