1,922 research outputs found
q-Newton binomial: from Euler to Gauss
A counter-intuitive result of Gauss (formulae (1.6), (1.7) below) is made
less mysterious by virtue of being generalized through the introduction of an
additional parameter
Evaluation of Maine Technology Institute Programs For Awards Ending July 1, 2006 - June 30, 2008
The Maine Technology Institute (MTI) is charged by the Legislature to conduct an evaluation of its programs every two years addressing issues of the effectiveness of MTI’s grant programs in fostering technology-based economic development. MTI has engaged the Maine Center for Business and Economic Research (MCBER) at the University of Southern Maine to conduct this evaluation. This is the fourth valuation report prepared by MCBER; previous reports were released in 2003, 2005, and 2007.
This report covers all MTI grants that were completed between July 1, 2006 and June 30, 2008, except for grants d th Cl t E h t P G t d th under the Cluster Enhancement Program. Grants under that program will be evaluated in the next evaluation prepared by MCBER to be released in 2010. All dates in this report refer to the fiscal year (July-June) in which a grant closed
Researchers explore Arctic freshwater\u27s role in ocean circulation
A critical, but insufficiently understood, component of global change is the influence of Arctic freshwater input on water mass exchange between the Arctic Ocean and Atlantic and Pacific Oceans. Four of the Earth\u27s 10 largest river systems, the Mackenzie, Ob,Yenisei, and Lena, contribute water to the Arctic shore (Figure 1) from a vast watershed that drains continental interiors. This river discharge flows into the world\u27s largest contiguous continental shelf and supplies over 50% (1823 km3 ) of the riverine input to the Arctic Ocean
Modelling time-varying gravity fields from Level-1B GRACE data using mascons
PhD ThesisAs an alternative to spherical harmonics, mass concentration (mascon) parameters have been successfully applied to the recovery of time-varying gravity (TVG) fields from the GRACE satellite mission. However, before meaningful mass anomalies can be estimated, the noise and errors inherent in the solutions needs to be quantified and appropriate procedures adopted for mitigation. The uniqueness of the mascon methodology is the capability to mitigate noise and errors using spatial and temporal constraints, which can be adapted and tailored to any geophysical signal of interest. Therefore, in the first instance, this work was motivated by the need to improve the accuracy of GRACE TVG fields by understanding the effect of noise and errors. This study then aims to validate mascons for recovery of basin scale inter-annual mass variability at a 10 day temporal resolution.
Newcastle University’s orbit determination software, Faust, was modified to allow for estimation of mascon parameters including: modelling of accelerometer bias values; mascon parameterisation; and processing based on short-arc gravity field recovery and KBRR data. Accuracy assessments were undertaken using simulations in the presence of realistic noise facilitating the comparison of mascons and spherical harmonic coefficients, including an assessment of potential limitations associated with each technique.
Comparisons with time-series derived from CSR RL05 Level-2 data validated the mascon TVG field recovery, before estimation of the mass change of Antarctica, Greenland and Alaska. Several hydrological basins, including the Amazon and Indus were also assessed before the GRACE trends resulting from the Sumatra earthquake of 2004 were investigated. While only provided for validation, these comparisons provide confidence in the mascon mass estimates. Between January 2003 and December 2013 a mass change of -83 ± 12 Gt/year and -242 ± 7 Gt/year were estimated for Antarctica and Greenland respectively by linear regression using mascons with a 10 day temporal resolution.
Overall, the work undertaken in this thesis provides evidence of the improved accuracy achievable when using mascon parameters to estimating TVG fields from Level-1B GRACE data.
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As part of this work a processing methodology to estimate mascon parameters from Level-1B GRACE data using Newcastle University’s orbit determination software Faust has been established and documented. This leaves the University well placed to continue processing mascon solutions from Level-1B GRACE data and to estimate mascon solutions from the GRACE-FO mission.
Through simulations, mascon parameters were found to offer advantages over spherical harmonics for the mitigation of noise and for improving the temporal and spatial recovery of the TVG field from GRACE. The mascon constraint matrix allowed more signal to be preserved up to degree ~35. Using basin constraints, simulation revealed that the constraint matric can be tuned to recovery the gravity changes resulting from any geophysical phenomena of interest. Basin constraints were found to optimise the signal recovery of GLDAS and a known mass change signal over Antarctica and Greenland. A novel way to create realistic noise and errors in the KBRR measurement was also documented.
Generating monthly and 10 day mascon solutions using real data revealed that the noise and errors in mascon solutions is comparably lower than in CRS RL05 solution while also validating the mascon methodology established here. Comparison to published mass trends to those estimated using mascon parameters showed that the estimation of mascon parameters has application in the study of mass change in the cryosphere, hydrological applications and for the study of the co-seismic mass changes resulting from earthquakes.NERC
Hardware implementation algorithm and error analysis of high-speed fluorescence lifetime sensing systems using center-of-mass method
A new, simple, high-speed, and hardware-only integrationbased fluorescence-lifetime-sensing algorithm using a center-of-mass method CMM is proposed to implement lifetime calculations, and its signal-to-noise-ratio based on statistics theory is also deduced. Compared to the commonly used iterative least-squares method or the maximum-likelihood-estimation–based, general purpose fluorescence lifetime imaging microscopy FLIM analysis software, the proposed hardware lifetime calculation algorithm with CMM offers direct calculation of fluorescence lifetime based on the collected photon counts and timing information provided by in-pixel circuitry and therefore delivers faster analysis for real-time applications, such as clinical diagnosis. A real-time hardware implementation of this CMM FLIM algorithm suitable for a single-photon avalanche diode array in CMOS imaging technology is now proposed for implementation on field-programmable gate array. The performance of the proposed methods has been tested on Fluorescein, Coumarin 6, and 1,8- anilinonaphthalenesulfonate in water/methanol mixture
The aerobraking space transfer vehicle
With the advent of the Space Station and the proposed Geosynchronous Operation Support Center (GeoShack) in the early 21st century, the need for a cost effective, reusable orbital transport vehicle has arisen. This transport vehicle will be used in conjunction with the Space Shuttle, the Space Station, and GeoShack. The vehicle will transfer mission crew and payloads between low earth and geosynchronous orbits with minimal cost. Recent technological advances in thermal protection systems such as those employed in the Space Shuttle have made it possible to incorporate and aerobrake on the transfer vehicle to further reduce transport costs. The research and final design configuration of the aerospace senior design team from VPISU, working in conjunction with NASA, are presented. The topic of aerobraking and focuses on the evolution of an Aerobraking Space Transfer Vehicle (ASTV), is addressed
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