Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158232
P. Dimitrov
The aim of this paper is to test an approach for analysis of inter-annual vegetation dynamics on the basis of FPAR and LAI data from MODIS. Central moving average filter and linear interpolation are both used for smoothing the initial time series. Time profiles of the biophysical parameters are drawn by the filtered data and they reflect vegetation seasonal development for the period 2000–2008. The inter-annual comparison of FPAR and LAI rely on dates when certain threshold values are reached and the period in which their values are above this thresholds. The standard deviation of the dates of reaching thresholds for the two biophysical parameters in this period is about ten days. The duration of the period in which FPAR and LAI are above the corresponding thresholds also varies in the same range. These variations do not differ from the usual inter-annual dynamics of the spruce communities.
{"title":"Investigation of dynamics of some biophysical parameters of Norway spruce stands by MODIS data","authors":"P. Dimitrov","doi":"10.1109/RAST.2009.5158232","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158232","url":null,"abstract":"The aim of this paper is to test an approach for analysis of inter-annual vegetation dynamics on the basis of FPAR and LAI data from MODIS. Central moving average filter and linear interpolation are both used for smoothing the initial time series. Time profiles of the biophysical parameters are drawn by the filtered data and they reflect vegetation seasonal development for the period 2000–2008. The inter-annual comparison of FPAR and LAI rely on dates when certain threshold values are reached and the period in which their values are above this thresholds. The standard deviation of the dates of reaching thresholds for the two biophysical parameters in this period is about ten days. The duration of the period in which FPAR and LAI are above the corresponding thresholds also varies in the same range. These variations do not differ from the usual inter-annual dynamics of the spruce communities.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130994091","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158249
G. Savu
The Black Sea could be used as safe space for launchings. It is analyzed the case of using the existing launch system of Orbital Corporation and a new, similar system with different carrier aircraft and different rocket. The dynamics of the single stage rocket on the ascending trajectory to low orbit (SSTO) together with the calculation of main dimensions and masses is analyzed. The obtained performances show that the Black Sea has enough space to ensure the frame for optimum launching of satellites from West to East. The rotation of Earth at the latitude of Black Sea ensures the satellization velocity at 7.6 km/s instead of 7.9.
{"title":"Using the Black Sea as airspace for satellites launching","authors":"G. Savu","doi":"10.1109/RAST.2009.5158249","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158249","url":null,"abstract":"The Black Sea could be used as safe space for launchings. It is analyzed the case of using the existing launch system of Orbital Corporation and a new, similar system with different carrier aircraft and different rocket. The dynamics of the single stage rocket on the ascending trajectory to low orbit (SSTO) together with the calculation of main dimensions and masses is analyzed. The obtained performances show that the Black Sea has enough space to ensure the frame for optimum launching of satellites from West to East. The rotation of Earth at the latitude of Black Sea ensures the satellization velocity at 7.6 km/s instead of 7.9.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"151 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121387768","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158180
O. Ozmen
The strain rate (time)-dependent mechanical behavior of PMR-15 neat resin, a thermoset polymer, was investigated at 316 °C. In order to investigate the inelastic deformation behavior of PMR-15, experimental program was designed to explore the effect of prior strain rate on monotonic loading and unloading, and relaxation behaviors. In addition, the recovery of strain at zero stress and the creep behavior following strain controlled loading were examined. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading and unloading. Early failures occur in the inelastic regime. The recovery of strain and creep response are profoundly influenced by prior strain rate. The material does not exhibit strain rate history effect. The prior strain rate also has a strong influence on the relaxation behavior.
{"title":"Inelastic deformation behavior of PMR-15 high temperature polymer at 316 °C","authors":"O. Ozmen","doi":"10.1109/RAST.2009.5158180","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158180","url":null,"abstract":"The strain rate (time)-dependent mechanical behavior of PMR-15 neat resin, a thermoset polymer, was investigated at 316 °C. In order to investigate the inelastic deformation behavior of PMR-15, experimental program was designed to explore the effect of prior strain rate on monotonic loading and unloading, and relaxation behaviors. In addition, the recovery of strain at zero stress and the creep behavior following strain controlled loading were examined. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading and unloading. Early failures occur in the inelastic regime. The recovery of strain and creep response are profoundly influenced by prior strain rate. The material does not exhibit strain rate history effect. The prior strain rate also has a strong influence on the relaxation behavior.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117179621","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158213
B. Sirmaçek, C. Unsalan
Building detection from very high resolution satellite imagery is an important task for land planners. However, manually locating buildings from these images is a difficult and time consuming process. Therefore, researchers focused on building detection using automated image processing and computer vision techniques. The main problems here are as follows. Buildings have diverse characteristics and their appearance (illumination, viewing angle, etc.) is uncontrolled. On the other hand, buildings often have similar cues like parallel edges and roof corners that can be merged. In this study, we propose an automated approach for building detection based on Gabor filters and spatial voting. We extract features (representing buildings) using Gabor filter responses. Using these features, we form a spatial voting matrix to detect buildings. We tested our algorithm on very high resolution grayscale Ikonos satellite images and obtained promising results.
{"title":"Building detection using local Gabor features in very high resolution satellite images","authors":"B. Sirmaçek, C. Unsalan","doi":"10.1109/RAST.2009.5158213","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158213","url":null,"abstract":"Building detection from very high resolution satellite imagery is an important task for land planners. However, manually locating buildings from these images is a difficult and time consuming process. Therefore, researchers focused on building detection using automated image processing and computer vision techniques. The main problems here are as follows. Buildings have diverse characteristics and their appearance (illumination, viewing angle, etc.) is uncontrolled. On the other hand, buildings often have similar cues like parallel edges and roof corners that can be merged. In this study, we propose an automated approach for building detection based on Gabor filters and spatial voting. We extract features (representing buildings) using Gabor filter responses. Using these features, we form a spatial voting matrix to detect buildings. We tested our algorithm on very high resolution grayscale Ikonos satellite images and obtained promising results.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125777399","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158292
C. Hamrouni, B. Neji, A. Alimi, K. Schilling
Small satellites, accomplished by new technologies, allowed the achievement of many tasks and experiments in space. In this context, Pico satellites team of Research Group on Intelligent Machines laboratory of the engineering school of Sfax, Tunisia, has designed and prototyped Microstrip antennas for the first Tunisian Pico satellite ERPSat-1 use. Its resonant frequency is 2.4 GHz. The various losses like atmospheric, free space, Ionosphere and rain losses are taken in consideration. Atmospheric and free space losses vary in accordance with the distance between the Pico satellite ERPSat1 and the ground antenna. During simulations, the changes of the earth antenna which are based on elevation angle, pointing and polarization losses should be taken in consideration. The obtained Microstrip antennas will be used for inter Picosatellites and their ground stations communication. In this paper, we present the design of the ERPSat-1 Microstrip antennas, the results and the limits of the used models to prove their use for space communications. As a first step, these Microstrip antennas will be used in remote sensing system for data transmission from camera to the FPGA platform developed in REGIM laboratory of Sfax University.
{"title":"Design and prototype of a flight microstrip antennas for the Pico satellite ERPSat-1","authors":"C. Hamrouni, B. Neji, A. Alimi, K. Schilling","doi":"10.1109/RAST.2009.5158292","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158292","url":null,"abstract":"Small satellites, accomplished by new technologies, allowed the achievement of many tasks and experiments in space. In this context, Pico satellites team of Research Group on Intelligent Machines laboratory of the engineering school of Sfax, Tunisia, has designed and prototyped Microstrip antennas for the first Tunisian Pico satellite ERPSat-1 use. Its resonant frequency is 2.4 GHz. The various losses like atmospheric, free space, Ionosphere and rain losses are taken in consideration. Atmospheric and free space losses vary in accordance with the distance between the Pico satellite ERPSat1 and the ground antenna. During simulations, the changes of the earth antenna which are based on elevation angle, pointing and polarization losses should be taken in consideration. The obtained Microstrip antennas will be used for inter Picosatellites and their ground stations communication. In this paper, we present the design of the ERPSat-1 Microstrip antennas, the results and the limits of the used models to prove their use for space communications. As a first step, these Microstrip antennas will be used in remote sensing system for data transmission from camera to the FPGA platform developed in REGIM laboratory of Sfax University.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126334627","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158189
Sam Scimemi
For many years, space faring nations have defined and implemented docking systems that have met the needs and constraints of their own programs. The American Gemini and Apollo programs in the 1960's developed docking mechanisms specific to lunar missions. The Russian Salyut, Soyuz and later Mir programs developed docking mechanisms that were specific to docking and mating of spacecraft in low earth orbit
{"title":"Human space flight docking interoperability","authors":"Sam Scimemi","doi":"10.1109/RAST.2009.5158189","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158189","url":null,"abstract":"For many years, space faring nations have defined and implemented docking systems that have met the needs and constraints of their own programs. The American Gemini and Apollo programs in the 1960's developed docking mechanisms specific to lunar missions. The Russian Salyut, Soyuz and later Mir programs developed docking mechanisms that were specific to docking and mating of spacecraft in low earth orbit","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126370704","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158186
A. Esbati, S. Irani
The purpose of this research is introducing a mathematical model for investigating the structural dynamic stability of a three stages launch vehicle. The intended aim of this research is to reveal the effect of concentrate masses on dynamic stability of launch vehicle under a constant thrust. The launch vehicle is modeled as a free-free Timoshenko beam with variable moment of inertia and module of elasticity for each stage. Dynamic stability study with respect to: 1- the magnitude of rotary inertia and shear deformation parameters of the beam 2- the magnitude of constant follower force. Both divergence and flutter can occur over the range of free-free Timoshenko model.
{"title":"Structural dynamic stability of three stages launch vehicle as a free-free Timoshenko beam subjected to follower force","authors":"A. Esbati, S. Irani","doi":"10.1109/RAST.2009.5158186","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158186","url":null,"abstract":"The purpose of this research is introducing a mathematical model for investigating the structural dynamic stability of a three stages launch vehicle. The intended aim of this research is to reveal the effect of concentrate masses on dynamic stability of launch vehicle under a constant thrust. The launch vehicle is modeled as a free-free Timoshenko beam with variable moment of inertia and module of elasticity for each stage. Dynamic stability study with respect to: 1- the magnitude of rotary inertia and shear deformation parameters of the beam 2- the magnitude of constant follower force. Both divergence and flutter can occur over the range of free-free Timoshenko model.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123629827","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158230
O. Bettemir
By using differential sensitivity analysis, horizontal and vertical accuracy of orthorectification of monoscopic images taken by small satellites without using Ground Control Points (GCP) is predicted. The analysis is performed by differentiating the colinearity equation of orthorectification procedure with respect to the satellite's interior and exterior parameters, and elevation obtained from digital elevation model (DEM). Square of the differential equations with respect to parameters are multiplied with the variance covariance matrix of the parameters and horizontal uncertainty of the orthorectification is obtained by summing the results of this multiplication. Vertical uncertainty is caused by the uncertainty of DEM and the uncertainty of the horizontal position. Vertical uncertainty caused by the horizontal uncertainty is predicted by estimating a trend by generating a surface polynomial from DEM on the basis of covariance function of Hirvonen. Contribution of each error source is illustrated and the most sensitive parameter is obtained. With this knowledge, special weight can be given to the most sensitive parameter and the uncertainty of the orthorectification can be decreased in the most efficient way.
{"title":"Differential sensitivity analysis for the orthorectification of small satellite images","authors":"O. Bettemir","doi":"10.1109/RAST.2009.5158230","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158230","url":null,"abstract":"By using differential sensitivity analysis, horizontal and vertical accuracy of orthorectification of monoscopic images taken by small satellites without using Ground Control Points (GCP) is predicted. The analysis is performed by differentiating the colinearity equation of orthorectification procedure with respect to the satellite's interior and exterior parameters, and elevation obtained from digital elevation model (DEM). Square of the differential equations with respect to parameters are multiplied with the variance covariance matrix of the parameters and horizontal uncertainty of the orthorectification is obtained by summing the results of this multiplication. Vertical uncertainty is caused by the uncertainty of DEM and the uncertainty of the horizontal position. Vertical uncertainty caused by the horizontal uncertainty is predicted by estimating a trend by generating a surface polynomial from DEM on the basis of covariance function of Hirvonen. Contribution of each error source is illustrated and the most sensitive parameter is obtained. With this knowledge, special weight can be given to the most sensitive parameter and the uncertainty of the orthorectification can be decreased in the most efficient way.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121935361","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158259
O. Tekinalp, Tuba C. Elmas, I. Yavrucuk
Momentum envelopes for a cluster of four CMGs in pyramid mounting are obtained. The envelopes when gimbal travel is limited to ±90° are also presented. CMG steering simulations using Moore Penrose pseudo inverse as well as blended inverse are presented, and success of the pre planned blended inverse in avoiding gimbal angle limits is demonstrated. Also given is a successful satellite slew maneuver example using blended inverse, showing the completion of the maneuver without violating gimbal angle travel restrictions.
{"title":"Gimbal angle restricted control moment gyroscope clusters","authors":"O. Tekinalp, Tuba C. Elmas, I. Yavrucuk","doi":"10.1109/RAST.2009.5158259","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158259","url":null,"abstract":"Momentum envelopes for a cluster of four CMGs in pyramid mounting are obtained. The envelopes when gimbal travel is limited to ±90° are also presented. CMG steering simulations using Moore Penrose pseudo inverse as well as blended inverse are presented, and success of the pre planned blended inverse in avoiding gimbal angle limits is demonstrated. Also given is a successful satellite slew maneuver example using blended inverse, showing the completion of the maneuver without violating gimbal angle travel restrictions.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130884195","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}
Pub Date : 2009-06-11DOI: 10.1109/RAST.2009.5158278
T. Colak, R. Qahwaji, S. Ipson, H. Ugail
Solar imaging is currently an active area of research. In this study a 3D modeling technique for magnetic field lines on Sun is provided. Magnetic field foot prints are detected from SOHO (Solar and Heliospheric Observatory) / MDI (Michelson Doppler Imager) Magnetogram images. Using negative and positive footprints possible dipole pairs are found according to their proximity. Then using this data, 3D models are built on bipolar coordinates and placed on detected pairs after transformations.
{"title":"3D modeling of magnetic field lines using SOHO/MDI magnetogram images","authors":"T. Colak, R. Qahwaji, S. Ipson, H. Ugail","doi":"10.1109/RAST.2009.5158278","DOIUrl":"https://doi.org/10.1109/RAST.2009.5158278","url":null,"abstract":"Solar imaging is currently an active area of research. In this study a 3D modeling technique for magnetic field lines on Sun is provided. Magnetic field foot prints are detected from SOHO (Solar and Heliospheric Observatory) / MDI (Michelson Doppler Imager) Magnetogram images. Using negative and positive footprints possible dipole pairs are found according to their proximity. Then using this data, 3D models are built on bipolar coordinates and placed on detected pairs after transformations.","PeriodicalId":412236,"journal":{"name":"2009 4th International Conference on Recent Advances in Space Technologies","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131103061","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}
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