Analysis of multi-layered films

Dye densities of multi-layered films are determined by applying a regression analysis to the spectral response of the composite transparency. The amount of dye in each layer is determined by fitting the sum of the individual dye layer densities to the measured dye densities. From this, dye content constants are calculated. Methods of calculating equivalent exposures are discussed. Equivalent exposures are a constant amount of energy over a limited band-width that will give the same dye content constants as the real incident energy. Methods of using these equivalent exposures for analysis of photographic data are presented

On the spatio-temporal analysis of hydrological droughts from global hydrological models

The recent concerns for world-wide extreme events related to climate change have motivated the development of large scale models that simulate the global water cycle. In this context, analysis of hydrological extremes is important and requires the adaptation of identification methods used for river basin models. This paper presents two methodologies that extend the tools to analyze spatio-temporal drought development and characteristics using large scale gridded time series of hydrometeorological data. The methodologies are classified as non-contiguous and contiguous drought area analyses (i.e. NCDA and CDA). The NCDA presents time series of percentages of areas in drought at the global scale and for pre-defined regions of known hydroclimatology. The CDA is introduced as a complementary method that generates information on the spatial coherence of drought events at the global scale. Spatial drought events are found through CDA by clustering patterns (contiguous areas). In this study the global hydrological model WaterGAP was used to illustrate the methodology development. Global gridded time series of subsurface runoff (resolution 0.5°) simulated with the WaterGAP model from land points were used. The NCDA and CDA were developed to identify drought events in runoff. The percentages of area in drought calculated with both methods show complementary information on the spatial and temporal events for the last decades of the 20th century. The NCDA provides relevant information on the average number of droughts, duration and severity (deficit volume) for pre-defined regions (globe, 2 selected hydroclimatic regions). Additionally, the CDA provides information on the number of spatially linked areas in drought, maximum spatial event and their geographic location on the globe. Some results capture the overall spatio-temporal drought extremes over the last decades of the 20th century. Events like the El Niño Southern Oscillation (ENSO) in South America and the pan-European drought in 1976 appeared clearly in both analyses. The methodologies introduced provide an important basis for the global characterization of droughts, model inter-comparison of drought identified from global hydrological models and spatial event analyse

Vortex-glass transition in superconducting Nb/Cu superlattices

Nb/Cu superconducting superlattices have been fabricated by dc magnetron sputtering. This system shows a vortex glass transition with critical exponents similar to high temperatures superconductors exponents. The transition dymensionality is governed by the superconducting coupling regime. The vortex glass transition shows a pure two dimensional behavior in decoupled superlattices and a quasi-two dimensional behavior in the superlattice coupling regime.Comment: 9 pages, 3 figure

Shuttle active thermal control system development testing. Volume 2: Modular radiator system tests

Tests were designed to investigate the validity of the "modular" approach to space radiator system design for space shuttle and future applications by gathering performance data on various systems comprised of different numbers of identical panels, subject to nominal and extreme heat loads and environments. Both one-sided and two-sided radiation was tested, and engineering data was gathered on simulated low a/e coatings and system response to changes in outlet temperature control point. The results of the testing showed system stability throughout nominal orbital transients, unrealistically skewed environments, freeze-thaw transients, and rapid changes in outlet temperature control point. Various alternative panel plumbing arrangements were tested with no significant changes in performance being observed. With the MRS panels arranged to represent the shuttle baseline system, a maximum heat rejection of 76,600 Btu/hr was obtained in segmented tests under the expected worst case design environments. Testing of an alternate smaller two-sided radiation configuration yielded a maximum heat rejection of 52,931 Btu/hr under the maximum design environments

Universal Behavior of the Resistance Noise across the Metal-Insulator Transition in Silicon Inversion Layers

Studies of low-frequency resistance noise show that the glassy freezing of the two-dimensional (2D) electron system in the vicinity of the metal-insulator transition occurs in all Si inversion layers. The size of the metallic glass phase, which separates the 2D metal and the (glassy) insulator, depends strongly on disorder, becoming extremely small in high-mobility samples. The behavior of the second spectrum, an important fourth-order noise statistic, indicates the presence of long-range correlations between fluctuators in the glassy phase, consistent with the hierarchical picture of glassy dynamics.Comment: revtex4; 4+ pages, 5 figure

Alternate high capacity heat pipe

The performance predictions for a fifty foot heat pipe (4 foot evaporator - 46 foot condensor) are discussed. These performance predictions are supported by experimental data for a four foot heat pipe. Both heat pipes have evaporators with axial groove wick structures and condensers with powder metal external artery wick structures. The predicted performance of a rectangular axial groove/external artery heat pipe operating in space is given. Heat transport versus groove width is plotted for 100, 200 and 300 grooves in the evaporator. The curves show that maximum power is achieved for groove widths from 0.040 to 0.053 as the number of grooves varies from 300 to 100. The corresponding range of maximum power is 3150 to 2400 watts. The relationships between groove width and heat pipe evaporate diameter for 100, 200 and 300 grooves in the evaporator are given. A four foot heat pipe having a three foot condenser and one foot evaporator was built and tested. The evaporator wick structure used axial grooves with rectangular cross sections, and the condenser wick structure used powder metal with an external artery configuration. Fabrication drawings are enclosed. The predicted and measured performance for this heat pipe is shown. The agreement between predicted and measured performance is good and therefore substantiates the predicted performance for a fifty foot heat pipe

Trophic classification of Tennessee Valley area reservoirs derived from LANDSAT multispectral scanner data

LANDSAT MSS data from four different dates were extracted from computer tapes using a semiautomated digital data handling and analysis system. Reservoirs were extracted from the surrounding land matrix by using a Band 7 density level slice of 3; and descriptive statistics to include mean, variance, and ratio between bands for each of the four bands were calculated. Significant correlations ( 0.80) were identified between the MSS statistics and many trophic indicators from ground truth water quality data collected at 35 reservoirs in the greater Tennessee Valley region. Regression models were developed which gave significant estimates of each reservoir's trophic state as defined by its trophic state index and explained in all four LANDSAT frames at least 85 percent of the variability in the data. To illustrate the spatial variations within reservoirs as well as the relative variations between reservoirs, a table look up elliptical classification was used in conjunction with each reservoir's trophic state index to classify each reservoir on a pixel by pixel basis and produce color coded thematic representations

The measurement of the W mass at the LHC: shortcuts revisited

The claim that the W mass will be measured at the LHC with a precision of $cal{O}$(10)~MeV is critically reviewed. It is argued that in order to achieve such precision, a considerably better knowledge of the $u_{m v}$, $d_{m v}$, $s$, $c$, and $b$ structure functions of the proton than available today is needed. This will permit to assess with adequate precision the production characteristics of the W and Z bosons in the proton--proton collisions at the LHC, and their effect on the $p_{m T}$ spectra of charged leptons from W and Z decays. An experimental programme is suggested that will deliver the missing information. The core of this programme is a dedicated muon scattering experiment at the CERN SPS, with simultaneous measurements on hydrogen and deuterium targets

Thin CubeSats and Compact Sensors for Constellations in VLEO to Deep Space

ThinSat form factors have many advantages for constellations and are launched directly from all standard 1U to 27U CubeSat canisters. Currently NSL is completing two 6U constellations for launch in 2023. The Space Weather NASA SBIR Phase II consists of 4 satellites, each with dimension 7.5x10x20cm. Novel and compressed Space Weather instruments are being developed by NSL partners. Each satellite can be divided into two ThinSat sections separated by a 20 cm foldout to serve as a 1) sensor boom, 2) quiet low noise Faraday sensor box, 3) passively cooled from -40 to + 40 C platform, and 4) cleaner sealed sensor environment depending on sensor requirements. The Space Force SBIR Phase II consists of four longer ThinSats with each dimension of 2.5x10x30cm. ThinSats can be connected together to form thicker satellites for larger subsystems and identified as 2T, 3T, 4T, and others. Significant ThinSat advantages include 1) Ease of robotic assembly at lower cost, 2) Larger surface area for solar cells and sensors compared to cubes, 3) Aerodynamic for low altitude ionospheric planetary measurements, 5) Ease for workflow and testing, and 6) Superior low-noise isolation. ThinSats also include 24/7 sat-links using improved Iridium (TX & RX) and previous Globalstar (TX) communication constellations. Recent NSL launches in the past two years will illustrate ThinSat sensor data and orbital results. GEARRS-3, TROOP-1, 2 and 3 launches and NSL ExoSat payload with many miniaturized sensors onboard is scheduled for 2023 launch on NASA EM-1 Deep Space measurements