Fontana F.M.A.,University of British Columbia |
Coops N.C.,University of British Columbia |
Khlopenkov K.V.,Enterprise Sciences, Inc. |
Trishchenko A.P.,Canada Center For Remote Sensing |
And 3 more authors.
Remote Sensing of Environment | Year: 2012
Time series of the Normalized Difference Vegetation Index (NDVI) derived from satellite observations provide important information on the state of terrestrial vegetation over a wide range of spatiotemporal scales. For understanding long-term changes in terrestrial ecosystems (post-1981), data collected by the Advanced Very High Resolution Radiometer (AVHRR) on board the satellites of National Oceanic and Atmospheric Administration (NOAA) series is a unique source of information. In this paper, we describe a new processing methodology for a comprehensive AVHRR data set at 1. km spatial resolution acquired over Canada, the northern United States and Greenland post-1981. The methodology incorporates a pre-processing algorithm, Canadian AVHRR Processing System (CAPS), recently developed by the Canada Centre of Remote Sensing (CCRS), which enables highly accurate geolocation and ortho-rectification at efficiency rates of > 90%. Once image navigation is completed, our approach consists of five key steps: first, two clear-sky composites for each 10. day interval are generated from the forward or backward scattering hemisphere; second, AVHRR Channel 1 and 2 reflectances are normalized to the AVHRR/3 on board NOAA-17 to account for differences in the spectral response function among the AVHRR sensors; third, atmospheric correction is performed using the Simplified Method for Atmospheric correction (SMAC) algorithm, using standard meteorological data sets (water vapor, surface level air pressure, ozone); fourth, NDVI is calculated based on atmospherically corrected Channel 1 and 2 reflectances; and finally, the NDVI is adjusted for directional effects based on the Ross-Thick Li-Sparse Bidirectional Reflectance Distribution Function (BRDF) model. The processed NDVI data are compared to an equivalent spatially and temporally overlapping MODIS NDVI data set from 2001 to 2005 for validation. Results at continental scale indicate that time series of MODIS and AVHRR were similar for a wide range of biomes and generalized ecoregions. Analysis stratified by land cover indicated that the correlation was strongest for homogeneous land cover types, such as cropland, when compared to structurally more diverse classes, such as deciduous broadleaf forests. The comparison of the NDVI at the local scale at seven sites of the Fluxnet Canada Research Network resulted in the correlation coefficient r = 0.95. Given confidence in the processing approach, this NDVI data set can be a valuable source of information for climate and vegetation-related studies over Canada and the northern United States. © 2012 Elsevier Inc. Source
Singh U.N.,NASA |
Yu J.,NASA |
Petros M.,NASA |
Refaat T.F.,Jefferson Lab |
And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014
Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 mJ and up to 10 Hz repetition rate. The two laser pulses are separated by 200 μs and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO2 measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-μm direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-μm IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity. © 2014 SPIE. Source
Mueller R.P.,NASA |
Sibille L.,Enterprise Sciences, Inc. |
Sanders G.B.,NASA |
Earth and Space 2014: Engineering for Extreme Environments - Proceedings of the 14th Biennial International Conference on Engineering, Science, Construction, and Operations in Challenging Environments | Year: 2014
Several asteroids are the targets of international robotic space missions currently manifested or in the planning stage. This global interest reflects a need to study these celestial bodies for the scientific information they provide about our solar system, and to better understand how to mitigate the collision threats some of them pose to Earth. Another important objective of these missions is providing assessments of the potential resources that asteroids could provide to future space architectures. In this paper, we examine a series of possible mission operations focused on advancing both our knowledge of the types of asteroids suited for different forms of resource extraction, and the capabilities required to extract those resources for mission enhancing and enabling uses such as radiation protection, propulsion, life support, shelter and manufacturing. An evolutionary development and demonstration approach is recommended within the framework of a larger campaign that prepares for the first landings of humans on Mars. As is the case for terrestrial mining, the development and demonstration approach progresses from resource prospecting (understanding the resource, and mapping the 'ore body'), mining/extraction feasibility and product assessment, pilot operations, to full in-situ resource utilization (ISRU). Opportunities to gather specific knowledge for ISRU via resource prospecting during science missions to asteroids are also examined to maximize the pace of development of needed ISRU capabilities and technologies for deep space missions. Source
Kaluf B.,Enterprise Sciences, Inc.
Journal of Prosthetics and Orthotics | Year: 2014
This study is a retrospective chart review of standardized outcome measure data assessing mobility in persons with lower-limb loss. Patient charts were reviewed after the recent adoption of outcome measures as standard practice at a multiregion prosthetic practice. The study investigated the effects of amputation level and assigned activity level (K-level) on patient-perceived potential for mobility and functional ambulatory potential. The Amputee Mobility Predictor (AMP) and Prosthesis Evaluation Questionnaire-Mobility Subscale (PEQ-MS) scores were obtained and compared between transtibial and transfemoral patients and stratified by K-level. An analysis of variance (ANOVA) of AMP and PEQ-MS scores yielded significant variation (a = 0.05) for amputation K-levels. A Fisher protected least significant difference post hoc test found that the K3 and K4 groups had significantly higher AMP with prosthesis (AMPPRO) and PEQ-MS scores than those of the K2 group. The AMP and PEQ-MS scores were not found to be significantly different among transtibial and transfemoral amputation levels in the population studied. These two outcome measures have shown promise for differentiating K-level when adopted as standard practice in the clinical setting. Copyright © 2014 American Academy of Orthotists and Prosthetists. Source
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase II | Award Amount: 1.50M | Year: 2011
Enterprise Sciences, Inc., and the University of Maryland School of Medicine have completed a Navy Phase I STTR feasibility and assessment study validating a new technology for portable devices that detect and monitor coagulopathy in traumatic injury and critically ill patients. This proposal is for a Phase II continuation of this work which will:Complete the validation of the technology with integrated breadboard blood sample testing from coagulopathic animal models; and produce an integrated One-of-Kind Alpha prototype demonstrating the ability to fabricate a rugged portable coagulopathy instrument