1,370 research outputs found

    A parameter estimation subroutine package

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    Linear least squares estimation and regression analyses continue to play a major role in orbit determination and related areas. A library of FORTRAN subroutines were developed to facilitate analyses of a variety of estimation problems. An easy to use, multi-purpose set of algorithms that are reasonably efficient and which use a minimal amount of computer storage are presented. Subroutine inputs, outputs, usage and listings are given, along with examples of how these routines can be used. The routines are compact and efficient and are far superior to the normal equation and Kalman filter data processing algorithms that are often used for least squares analyses

    A parameter estimation subroutine package

    Get PDF
    Linear least squares estimation and regression analyses continue to play a major role in orbit determination and related areas. FORTRAN subroutines have been developed to facilitate analyses of a variety of parameter estimation problems. Easy to use multipurpose sets of algorithms are reported that are reasonably efficient and which use a minimal amount of computer storage. Subroutine inputs, outputs, usage and listings are given, along with examples of how these routines can be used

    A parameter estimation subroutine package

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    Linear least squares estimation and regression analyses continue to play a major role in orbit determination and related areas. In this report we document a library of FORTRAN subroutines that have been developed to facilitate analyses of a variety of estimation problems. Our purpose is to present an easy to use, multi-purpose set of algorithms that are reasonably efficient and which use a minimal amount of computer storage. Subroutine inputs, outputs, usage and listings are given along with examples of how these routines can be used. The following outline indicates the scope of this report: Section (1) introduction with reference to background material; Section (2) examples and applications; Section (3) subroutine directory summary; Section (4) the subroutine directory user description with input, output, and usage explained; and Section (5) subroutine FORTRAN listings. The routines are compact and efficient and are far superior to the normal equation and Kalman filter data processing algorithms that are often used for least squares analyses

    Joint Report of Peer Review Panel for Numeric Nutrient Criteria for the Great Bay Estuary New Hampshire Department of Environmental Services June, 2009

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    This peer review was authorized through a collaborative agreement sponsored by the New Hampshire Department of Environmental Services (DES) and the Cities of Dover, Rochester and Portsmouth, New Hampshire. The purpose was to conduct an independent scientific peer review of the document entitled, ā€œNumeric Nutrient Criteria for the Great Bay Estuary,ā€ dated June, 2009 (DES 2009 Report)

    Understanding earth\u27s eroding surface with \u3csup\u3e10\u3c/sup\u3eBe

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    For more than a century, geologists have sought to measure the distribution of erosion rates on Earth\u27s dynamic surface. Since the mid-1980s, measurements of in situ 10Be, a cosmogenic radionuclide, have been used to estimate outcrop and basin-scale erosion rates at 87 sites around the world. Here, we compile, normalize, and compare published 10Be erosion rate data (n = 1599) in order to understand how, on a globalscale, geologic erosion rates integrated over 103 to 106 years varybetween climate zones, tectonic settings, and different rock types. Drainage basins erodemore quickly (mean = 218 m Myr-1; median = 54 m Myr-1) than outcrops (mean = 12 m Myr-1; median = 5.4 m Myr-1), likely reflecting the acceleration of rock weathering rates under soil. Drainage basin and outcrop erosion rates both vary by climate zone, rock type, and tectonic setting. On the global scale, environmental parameters (latitude, elevation, relief, mean annual precipitation and temperature, seismicity, basin slope and area, and percent basin cover by vegetation) explain erosion rate variation better when they are combined in multiple regression analyses than whenconsidered in bivariate relationships. Drainage basin erosion rates are explained well byconsidering these environmental parameters (R2 = 0.60); mean basin slope is the most powerful regressor. Outcrop erosion rates are less well explained (R2 =0.32), and no one parameter dominates. The variance of erosion rates is better explained when subpopulations of the global data are analyzed. While our compilation is global, thegrouped spatial distribution of cosmogenic studies introduces a bias that will only be addressed by research in under-sampled regions

    Rates of erosion and landscape change along the Blue Ridge escarpment, southern Appalachian Mountains, estimated from in situ cosmogenic 10Be

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    The Blue Ridge escarpment, located within the southern Appalachian Mountains of Virginia and North Carolina, forms a distinct, steep boundary between the lower-elevation Piedmont and higher-elevation Blue Ridge physiographic provinces. To understand better the rate at which this landform and the adjacent landscape are changing, we measured cosmogenic 10Be in quartz separated from sediment samples (nā€‰=ā€‰50) collected in thirty-two streams and from three exposed bedrock outcrops along four transects normal to the escarpment, allowing us to calculate erosion rates integrated over 104ā€“105 years. These basin-averaged erosion rates (5.4ā€“49ā€‰m My-1) are consistent with those measured elsewhere in the southern Appalachians and show a positive relationship between erosion rate and average basin slope. Erosion rates show no relationship with basin size or relative position of the Brevard fault zone, a fundamental structural element of the region. The cosmogenic isotopic data, when considered along with the distribution of average basin slopes in each physiographic province, suggest that the escarpment is eroding on average more rapidly than the Blue Ridge uplands, which are eroding more rapidly than the Piedmont lowlands. This difference in erosion rates by geomorphic setting suggests that the elevation difference between the uplands and lowlands adjacent to the escarpment is being reduced but at extremely slow rates

    The North American Free Trade Agreement: A Market Analysis

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    The North American Free Trade Agreement (NAFTA) was the subject of heated debate in the United States Congress. The central issue of the debate was whether NAFTA would have a positive or negative economic impact on the parties to the treaty. This Article is a direct empirical market analysis that measures the perceived economic impact of NAFTA on the parties to the agreement and other states. The authors use stock market event analysis to study the effect of NAFTA on different sectors of the economy of the United States, Mexico, Canada, Europe, and the Asia/Pacific region. In doing so, the authors test the hypothetical predictions of other scholars and conclude that, contrary to speculation, NAFTA has had no meaningful economic impact on the economies of the United States and Canada, a strong positive economic effect on Mexico\u27s economy, a slight positive economic effect on Europe, and a slight negative economic effect on the Asia/Pacific region

    Evaluation of Pt, Ni, and Niā€“Mo electrocatalysts for hydrogen evolution on crystalline Si electrodes

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    The dark electrocatalytic and light photocathodic hydrogen evolution properties of Ni, Niā€“Mo alloys, and Pt on Si electrodes have been measured, to assess the viability of earth-abundant electrocatalysts for integrated, semiconductor coupled fuel formation. In the dark, the activities of these catalysts deposited on degenerately doped p^+-Si electrodes increased in the order Ni < Niā€“Mo ā‰¤ Pt. Niā€“Mo deposited on degenerately doped Si microwires exhibited activity that was very similar to that of Pt deposited by metal evaporation on planar Si electrodes. Under 100 mW cm^(āˆ’2) of Air Mass 1.5 solar simulation, the energy conversion efficiencies of p-type Si/catalyst photoelectrodes ranged from 0.2ā€“1%, and increased in the order Ni ā‰ˆ Niā€“Mo < Pt, due to somewhat lower photovoltages and photocurrents for p-Si/Niā€“Mo relative to p-Si/Ni and p-Si/Pt photoelectrodes. Deposition of the catalysts onto microwire arrays resulted in higher apparent catalytic activities and similar photoelectrode efficiencies than were observed on planar p-Si photocathodes, despite lower light absorption by p-Si in the microwire structures
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