2009 IEEE Aerospace conference最新文献_第10页

Return to Europa: Overview of the Jupiter Europa Orbiter mission 返回木卫二:木星木卫二轨道飞行器任务概述

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839315

K. Clark, G. Tan-Wang, J. Boldt, R. Greeley, I. Jun, R. Lock, J. Ludwinski, R. Pappalardo, T. van Houten, T. Yan

引用次数: 40

In situ sampling using Meta-Stable Helium 利用亚稳定氦原位取样

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839322

Mark Anderson, A. Allwood

引用次数: 0

Hardware autonomy and space systems 硬件自治和空间系统

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839512

Neil Steiner, P. Athanas

引用次数: 17

Using decision trees to detect and isolate simulated leaks in the J-2X rocket engine 使用决策树检测和隔离J-2X火箭发动机的模拟泄漏

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839691

M. Schwabacher, R. Aguilar, F. Figueroa

{"title":"Using decision trees to detect and isolate simulated leaks in the J-2X rocket engine","authors":"M. Schwabacher, R. Aguilar, F. Figueroa","doi":"10.1109/AERO.2009.4839691","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839691","url":null,"abstract":"The goal of this work was to use data-driven methods to automatically detect and isolate faults in the J-2X rocket engine. It was decided to use decision trees, since they tend to be easier to interpret than other data-driven methods. The decision tree algorithm automatically “learns” a decision tree by performing a search through the space of possible decision trees to find one that fits the training data (with the hope that this tree will also generalize to new data). The particular decision tree algorithm used is known as C4.5. Simulated J-2X data from a high-fidelity simulator developed at Pratt & Whitney Rocketdyne and known as the Detailed Real-Time Model (DRTM) was used to “train” and test the decision tree. Fifty-six DRTM simulations were performed for this purpose, with different leak sizes, different leak locations, and different times of leak onset. To make the simulations as realistic as possible, they included simulated sensor noise, and included a gradual degradation in both fuel and oxidizer turbine efficiency. A decision tree was trained using 11 of these simulations, and tested using the remaining 45 simulations. In the training phase, the C4.5 algorithm was provided with labeled examples of data from nominal operation and data including leaks in each leak location. From the data, it “learned” a decision tree that can classify unseen data as having no leak or having a leak in one of the five leak locations. In the test phase, the decision tree produced very low false alarm rates and low missed detection rates on the unseen data. It had very good fault isolation rates for three of the five simulated leak locations, but it tended to confuse the remaining two locations, perhaps because a large leak at one of these two locations can look very similar to a small leak at the other location.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116374705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16

Active constellation modification techniques for OFDM PAR reduction 减少OFDM PAR的主动星座修改技术

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839406

R. Prabhu, E. Grayver

{"title":"Active constellation modification techniques for OFDM PAR reduction","authors":"R. Prabhu, E. Grayver","doi":"10.1109/AERO.2009.4839406","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839406","url":null,"abstract":"OFDM is a widely adopted modulation technique for wireless communication. However, the OFDM waveform still suffers from a large peak-to-average power ratio (PAR). Larger PAR leads to higher transmit power inefficiency. In this paper, we compare two constellation modification techniques, constellation distortion (CD) and active constellation extension (ACE), to reduce the PAR of the OFDM waveform. Both techniques are similar, in the sense that the constellation symbols are modified to reduce PAR. In CD, the tradeoff is between PAR reduction and added distortion, which results in a larger bit error rate (BER). In ACE, the tradeoff is between added power and PAR reduction. A metric called normalized total power (NTP) is introduced to facilitate a comparison between these two different techniques. Using this metric, we compare the performance of the two techniques using an 802.11a OFDM waveform. We present comparisons, via simulation, in both coded and uncoded cases. The simulation results show that, for an uncoded OFDM system, ACE performs better than CD for all constellations except QPSK. However, CD is preferred over ACE when coding is present. NTP improvements using CD can be up to 4.1dB in the case of coded QPSK and up to 0.8 dB using ACE for uncoded QPSK.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115173169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Comparison and integration of GPS and DInSAR deformation time-series GPS与DInSAR变形时间序列的比较与整合

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839342

M. Calamia, G. Franceschetti, R. Lanari, F. Casu, M. Manzo

引用次数: 2

Achieving a prioritized research & technology development portfolio for the Dust Management Project 实现粉尘管理项目的优先研究和技术开发组合

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839715

R. Kohli, J. Fishman, M. Hyatt, P. Abel, P. DeLaune

引用次数: 1

Condition based maintenance of military ground vehicles 军用地面车辆的状态维修

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839683

Eric Rabeno, Mark S. Bounds

{"title":"Condition based maintenance of military ground vehicles","authors":"Eric Rabeno, Mark S. Bounds","doi":"10.1109/AERO.2009.4839683","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839683","url":null,"abstract":"The performance of military ground vehicle systems quickly degrades due to high operation tempo and extreme environments while performing in-theater service. Current maintenance methods associated with this degradation are not sufficiently optimized for cost and performance. To address this issue, the United States Army is implementing a policy of Condition Based Maintenance (CBM) and being supported by the Army Materiel System Analysis Activity (AMSAA). CBM is a plan of maintenance for a system based upon the actual condition of the system as enabled by the application of usage, diagnostic and prognostic processes executed on a Health and Usage Monitoring System (HUMS). AMSAA has developed and is implementing a CBM system for ground vehicles. This development process has included the development of a robust military-grade HUMS in conjunction with the Aberdeen Test Center and the development of data collection, reduction, analysis, and reporting processes. A key requirement underlying these processes is a thorough understanding of both the ways in which system condition is degenerated and the ability of the HUMS to detect, identify, and communicate all conditions that requires maintenance in a timely manner. AMSAA and the US Army Aberdeen Test Center (ATC) have jointly initiated testing and applications as the critical means of filling this requirement.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115317754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

On-board multi-objective mission planning for Unmanned Aerial Vehicles 无人机机载多目标任务规划

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839608

P. Wu, D. Campbell, T. Merz

引用次数: 31

CLEAN technique in strip-map SAR for high-quality imaging 条带图SAR中的CLEAN技术实现高质量成像

2009 IEEE Aerospace conference Pub Date : 2009-03-07 DOI: 10.1109/AERO.2009.4839474

H. Ghaemi, M. Galletti, T. Boerner, F. Gekat, M. Viberg

{"title":"CLEAN technique in strip-map SAR for high-quality imaging","authors":"H. Ghaemi, M. Galletti, T. Boerner, F. Gekat, M. Viberg","doi":"10.1109/AERO.2009.4839474","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839474","url":null,"abstract":"The maximum obtainable resolution of a strip-map synthetic aperture radar (SAR) system can be retained by simply avoiding weighting, or tapering, data samples in the along-track compression process. However, this will lead to hazardous artifacts caused by strong sidelobes of the corresponding adjacent scatterers whose interference might severely weaken the desired targets or even introduce false targets. On the other hand, some residual artifacts, even after tapering process, may still deteriorate the quality (contrast) of the SAR image. These issues can be remedied by applying the so-called CLEAN technique, which can mitigate these ill-effects in strip-map SAR imagery while maintaining the maximum resolution. This, indeed, is carried out as a post processing step, i.e., after the azimuth compression is accomplished, in the SAR system. The objective of this paper is to extend the CLEAN technique to strip-map SAR system to produce high-quality images with a very good along-track resolution. The algorithm is then applied to data from a ground-based circular SAR (CSAR) system to verify its implementation as well as this new application of the CLEAN technique.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123514424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16