16,041 research outputs found
Correction function in the Lidar equation and the solution techniques for CO2 Lidar date reduction
For lidar systems with long laser pulses the unusual behavior of the near-range signals causes serious difficulties and large errors in reduction. The commonly used lidar equation is no longer applicable since the convolution of the laser pulse with the atmospheric parameter distributions should be taken into account. It is important to give more insight into this problem and find the solution techniques. Starting from the original equation, a general form is suggested for the single scattering lidar equation where a correction function Cr is introduced. The correction Function Cr(R) derived from the original equation indicates the departure from the normal lidar equation. Examples of Cr(R) for a coaxial CO2 lidar system are presented. The Differential Absorption Lidar (DIAL) errors caused by the differences of Cr(R) for H2O measurements are plotted against height
Evaluation of existing and new methods of tracking glacier terminus change
ACKNOWLEDGEMENTS The authors thank two anonymous reviewers for constructive comments that helped to improve the manuscript. This research was financially supported by J.M.L.’s PhD funding from UK Natural Environment Research Council grant No. NE/I528742/1.Peer reviewedPublisher PD
Enhanced Convergence and Robust Performance of Randomized Dynamical Decoupling
We demonstrate the advantages of randomization in coherent quantum dynamical
control. For systems which are either time-varying or require decoupling cycles
involving a large number of operations, we find that simple randomized
protocols offer superior convergence and stability as compared to deterministic
counterparts. In addition, we show how randomization always allows to
outperform purely deterministic schemes at long times, including combinatorial
and concatenated methods. General criteria for optimally interpolating between
deterministic and stochastic design are proposed and illustrated in explicit
decoupling scenarios relevant to quantum information storage.Comment: 4 pages, 3 figures, replaced with final versio
Research interventions to strengthen irrigators' associations
Irrigation management, Water distribution, Financing, Data collection, Operations, Maintenance, Performance indexes, Privatization, Farmer-agency interactions, Institution building, Farmers associations, Training, Participatory management, Leadership, Farm Management, Institutional and Behavioral Economics, Research and Development/Tech Change/Emerging Technologies, Teaching/Communication/Extension/Profession,
Fuzzy logic control for camera tracking system
A concept utilizing fuzzy theory has been developed for a camera tracking system to provide support for proximity operations and traffic management around the Space Station Freedom. Fuzzy sets and fuzzy logic based reasoning are used in a control system which utilizes images from a camera and generates required pan and tilt commands to track and maintain a moving target in the camera's field of view. This control system can be implemented on a fuzzy chip to provide an intelligent sensor for autonomous operations. Capabilities of the control system can be expanded to include approach, handover to other sensors, caution and warning messages
Thyroid hormones correlate with field metabolic rate in ponies, Equus ferus caballus
Acknowledgments The authors thank Jürgen Dörl for technical help and for taking care of the animals and Peter Thompson for technical assistance with the doubly labelled water analysis. Funding The study was supported by a grant from the German Research Foundation (DFG;GE 704/13-1).Peer reviewedPublisher PD
Einstein Observatory solid state spectrometer observations of M87 and the Virgo cluster
X-ray observations of the galaxy M87 and of a region in the Virgo cluster displaced 7 minutes from the center of M87 are presented. X-ray spectra are obtained at these two locations with the slid state spectrometer onboard the Einstein Observatory. Emission lines were observed in both locations, indicating the presence of heavy elements at abundances approximately solar (to within a factor of 2). A temperature gradient, T increases from approximately 1.4 keV at the position of M87 to T approximately 3.35 keV 7' away, was detected. There is lower temperature thermal emission at the center of M87 with T approximately 0.6 keV, consistent with models for cooling flows in this cluster. In addition to the thermal emission, a power law component in the spectrum of M87, was detected consistent with that observed by HEAO-1, indicating that this component probably originates in the galaxy itself. The presence of intracluster gas having density approximately .001 cu cm and temperature approximately 30 million K is indicated
Transfer of ultra-low phase noise microwave references over the JANET Aurora fibre network using a femtosecond optical frequency comb
An ultra-low phase noise microwave frequency is transferred over 82 km of installed fibre by propagation of a 30 nm bandwidth optical frequency comb (104 modes). The phase noise induced along the fibre by vibrations and thermal effects is suppressed by implementing a noise cancellation scheme where a portion of the light is sent back to the transmitter through the same fibre. The 6th harmonic of the repetition rate detected before and after the pulse train has travelled a round trip are phase compared and used to generate an error signal that controls a fibre stretcher to compensate for the fibre-induced phase fluctuations. Optical amplifiers are used to compensate for the fibre attenuation and dispersion compensation modules are also employed
Closing the Gap or Reaching the Ceiling: An Exploratory Trend Analysis of The Black White Achievement Gap in Texas
The academic achievement gap is an intriguing issue in educational research across the nation, as well as one of the most serious problems facing the United States. Texas has shown tremendous success in narrowing the difference between the percentage of White students and students of color that pass the TAAS and TAKS over two consecutive decades. This study investigated identified evidence a “ceiling effect” may mediate the results of two decades of assessments in the state of Texas. The results suggest that the growth patterns for African American students pass rates were consistently larger than White student growth trajectories, but because the White students begin with substantially larger pass rates there growth was limited. This study yields significant implication for further research and subsequent testing administrations. Researchers suggest that efforts shift from “gap gazing” to “pattern praising” or the identification of positive achievement patterns that represent progress rather and emphasis on the deficit
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