Analysis and applications of a general boresight algorithm for the DSS-13 beam waveguide antenna

A general antenna beam boresight algorithm is presented. Equations for axial pointing error, peak received signal level, and antenna half-power beamwidth are given. A pointing error variance equation is derived that illustrates the dependence of the measurement estimation performance on the various algorithm inputs, including RF signal level uncertainty. Plots showing pointing error uncertainty as function of algorithm inputs are presented. Insight gained from the performance analysis is discussed in terms of its application to the areas of antenna controller and receiver interfacing, pointing error compensation, and antenna calibrations. Current and planned applications of the boresight algorithm, including its role in the upcoming Ka-band downlink experiment (KABLE), are highlighted

An analysis of the least-squares problem for the DSN systematic pointing error model

A systematic pointing error model is used to calibrate antennas in the Deep Space Network. The least squares problem is described and analyzed along with the solution methods used to determine the model's parameters. Specifically studied are the rank degeneracy problems resulting from beam pointing error measurement sets that incorporate inadequate sky coverage. A least squares parameter subset selection method is described and its applicability to the systematic error modeling process is demonstrated on Voyager 2 measurement distribution

Application of optimal control theory to the design of the NASA/JPL 70-meter antenna servos

The application of Linear Quadratic Gaussian (LQG) techniques to the design of the 70-m axis servos is described. Linear quadratic optimal control and Kalman filter theory are reviewed, and model development and verification are discussed. Families of optimal controller and Kalman filter gain vectors were generated by varying weight parameters. Performance specifications were used to select final gain vectors

Critical Exponents in a Quantum Phase Transition of an Anisotropic 2D Antiferromagnet

I use the two-step density-matrix renormalization group method to extract the critical exponents $\beta$ and $\nu$ in the transition from a N\'eel $Q=(\pi,\pi)$ phase to a magnetically disordered phase with a spin gap. I find that the exponent $\beta$ computed from the magnetic side of the transition is consistent with that of the classical Heisenberg model, but not the exponent $z\nu$ computed from the disordered side. I also show the contrast between integer and half-integer spin cases.Comment: 4 pages, 2 figure

Thermal stability of the cu-ceo2 interface on silica and alumina, and its relation with activity in the oxidation reaction of co and the decomposition of n2o

Indexación: Scopus; Scielo.The effect of the support on the formation of the Cu-CeO2 interface and its thermal stability after calcination at 500, 700 and 900 °C is studied. The supports used are SiO2, because of its inert character, and Al2O3, because it can interact with the Cu and Ce species on the surface. The catalysts were characterized by BET, XRD, UV-vis DRS, and TPR with H2. The catalytic activity in the CO oxidation reactions with O2 at low temperature and the decomposition of N2O were selected to visualize the effect of temperature on the concentration of Cu-CeO2 interfacial sites. The results show that at a calcination temperature of 500 °C the formation of the Cu-CeO2 interface is favored over the SiO2 support. However, the stability of the Cu-CeO2 interface on SiO2 is much lower than on Al2O3, causing a substantial decrease of the interfacial sites calcining at 700 °C, and segregation of the Cu and Ce species on the surface of the silica, with complete loss of the catalytic activity in both reactions when calcining at 900 °C. In contrast, on alumina the Cu-CeO2 interface is more stable and presents a significant catalytic activity in both reactions, even when calcining at 900 °C. The characterization results show that the sintering process of Cu species and CeO2 particles is less on the alumina support due to the greater interaction of the Cu and Ce with this support. © 2018 Sociedad Chilena de Quimica.all rights reserved.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072018000304102&lng=en&nrm=iso&tlng=e

Balance histórico de nitrógeno, fósforo y azufre de la región pampeana

Se realizó un balance de superfice de nitrógeno (N), fósforo (P) y azufre (S) para la Región Pampena desde 1870 a 2010, período en que se produjo la expansión agrícola en la región. Para N se computaron como entradas el aporte atmósferico, la fijación simbiótica y la fertilización. Las salidas fueron la exportación en grano y productos animales. Para P y S el balance incluyó como entradas el aporte atmosférico y la fertilización y como salidas las mismas que para N. El balance se calculó en forma anual y acumulada y también se calculó la relación salida/entrada anual. Las bases de datos fueron censos nacionales y estadísticas oficiales para estimar las salidas y se hicieron estimaciones de aporte atmosférico, fijación simbiótica y consumo de fertilizantes. La entrada de N fue de 202 Mt, siendo el aporte atmósférico (36%) y la fijación simbiótica (58%) los componentes principales. La salida fue de 76 Mt, con la exportación en grano como principal factor (83%); resultando en un balance positivo de 126 Mt. Este flujo equivale a un cuarto del stock de N de los suelos hasta 1 m. Otros estudios mostraron que no se produjeron cambios en los stock de N pampeano entre 1960-80 y 2007-2008, período durante el cual el balance de N fue de +52 Mt. En consecuencia, se estimaron pérdidas gaseosas o por lixiviación durante este lapso de 26 kg ha-1 año-1. Para fósforo la entrada fue 4,2 Mt, con mayor peso del componente fertilizantes (67%) y la salida de 12,2 Mt, generado sobre todo por la cosecha de granos (76%), determinando un balance negativo de -8,0 Mt. La entrada de azufre fue de 3,9 Mt, principalmente generada por la atmósfera (81%) y la salida de 5,6 Mt, debido sobre todo a la exportación en grano (82%), con un balance negativo de -1,7 Mt. Estos resultados indican pérdida de P y S desde las reservas de los suelos. La relación salida/entrada de N pasó de 0,2 a 0,7 en el lapso estudiado, mientras que para P y S ha sido mayor a 1 desde hace décadas.A surface balance for nitrogen (N), phosphorus (P), and sulfur (S) was performed for the Argentine Pampas during the 1870- 2010 time interval, comprising the agricultural expansion period in the region. Nitrogen inputs accounted in the balance were atmospheric deposition, symbiotic fixation, and fertilization. Outputs included were grain harvest and livestock products. P and S balances included atmospheric deposition and fertilization as inputs and the same outputs than in the case of N balance. Annual and cumulative balances were calculated and also an annual output/input ratio. National information and official statistics were used to determine the nutrient outputs whereas atmospheric deposition, symbiotic fixation, and fertilizer inputs were estimated. Cumulative N input was of 202 Mt, atmospheric deposition (36%) and symbiotic fixation (58%) represented the main components. The output was of 76 Mt, with grain harvest as main factor (83%), thus resulting in a positive N balance of 126 Mt. This nutrient flow is equivalent to one quart of the soil N stock to 1 m depth. As previous studies showed that soil N stock did not changed between 1960-1980 and 2007-2008, period during which a positive N balance of 52 Mt was calculated, this resulted in a loss of 26 kg ha-1 yr-1 due to gas emissions and leaching in recent decades. Phosphorus input was 4.2 Mt, mainly explained by fertilization (67%), and the output was 12.2 Mt, generated mainly by grain harvest (76%), which determined a negative balance of -8.0 Mt. Sulfur input was 3.9 Mt, mainly determined by atmospheric deposition (81%) and the output was 5.6 Mt, mainly due to grain harvest (82%) resulting also in a negative balance of -1.7 Mt. These results indicate P and S losses from soil stocks. The N output/input ratio varied from 0.2 to 0.7 along the study period, while the P and S ratios have been higher than 1 since decades.Fil: Alvarez, Roberto. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; ArgentinaFil: Steinbach, Haydee S.. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: de Paepe, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentin