A5103380135- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Adaptive optics and wavefront sensing
- Photovoltaic System Optimization Techniques
- solar cell performance optimization
- Silicon and Solar Cell Technologies
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Solar Radiation and Photovoltaics
- Solar Thermal and Photovoltaic Systems
- Photovoltaic Systems and Sustainability
- Optical Systems and Laser Technology
- Astrophysical Phenomena and Observations
- CCD and CMOS Imaging Sensors
- Advanced optical system design
- Astro and Planetary Science
- Calibration and Measurement Techniques
- Astrophysics and Cosmic Phenomena
- Chalcogenide Semiconductor Thin Films
- Pulsars and Gravitational Waves Research
- Advanced Surface Polishing Techniques
- Biofuel production and bioconversion
- Semiconductor Quantum Structures and Devices
University of Cambridge
2010-2022
Durham University
2022
Sto (Germany)
2020
Arcetri Astrophysical Observatory
2020
Harvard University Press
2016
Sandia National Laboratories
1996-2011
Emcore (United States)
2011
Richland College
2009
Sandia National Laboratories California
1981-2006
Office of Scientific and Technical Information
2004
view Abstract Citations (388) References (103) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Metal Enrichment, Dust, and Star Formation in Galaxies at High Redshifts. III. Zn CR Abundances for 17 Damped Lyman-Alpha Systems Pettini, Max ; Smith, Linda J. Hunstead, Richard W. King, David L. We present measurements of the abundances zinc chromium a moderately large sample damped Lyman-α systems redshifts between z_abs_ = 1.78 3.03; includes approximately...
The term "temperature coefficient" has been applied to several different photovoltaic performance parameters, including voltage, current and power. procedures for measuring the coefficient(s) modules arrays are not yet standardized systematic influences common in test methods used measure them. There also misconceptions regarding their application. Yet, temperature coefficients, however obtained, play an important role PV power system design sizing, where often worst case operating condition...
This paper summarizes test procedures, results, and implications of in-depth investigations the performance durability characteristics commercial photovoltaic modules after long-term field exposure. New diagnostic procedures for module reliability research are discussed illustrated. A collaborative effort with US manufacturers aimed at achieving 30-year lifetimes is also described. Copyright © 2000 John Wiley & Sons, Ltd.
We report new observations of ZnII and CrII absorption lines in 10 damped \lya systems (DLAs), mostly at redshift $z_{abs} \simgt 2.5$ . By combining these results with those from our earlier survey (Pettini et al. 1994) other recent data, we construct a sample 34 measurements (or upper limits) the Zn abundance relative to hydrogen [Zn/H]; includes more than one third total number DLAs known. The plot as function reinforces two main findings previous study. (1) Damped are metal-poor, all...
The A5V star Alcor has an M3–M4 dwarf companion, as evidenced by a novel astrometric technique. Imaging spectroscopy combined with adaptive optics coronagraphy allowed for the detection and spectrophotometric characterization of point source at contrast ∼6 J- H-band magnitudes separation 1'' from primary star. use pupil plane grid us to determine projected separations between companion coronagraphically occulted ⩽3 mas precision two observation epochs. Our measurements demonstrate common...
This paper provides new test methods and analytical procedures for characterizing the electrical performance of photovoltaic modules arrays. The use outdoor measurements to provide parameters both at standard reporting conditions all operating encountered by typical systems. Improvements over previously used are identified, examples successful application methodology provided crystalline- amorphous-silicon work an improved understanding module array characteristics, perhaps most importantly,...
Historically, two time-of-day dependent factors have complicated the characterization of photovoltaic module and array performance; namely, changes in solar spectrum over day optical effects that vary with angle-of-incidence. This paper describes straightforward methods for directly measuring these factors. Measured results commercial modules, as well typical irradiance sensors (pyranometers) are provided. The empirical relationships obtained from measurements can be used to improve system...
We describe a new instrument that forms the core of long-term high contrast imaging program at 200 inch (5 m) Hale Telescope Palomar Observatory. The primary scientific thrust is to obtain images and low-resolution spectroscopy brown dwarfs young exoplanets several Jupiter masses in vicinity stars within 50 pc Sun. microlens-based integral field spectrograph integrated with diffraction-limited, apodized-pupil Lyot coronagraph. entire combination mounted behind adaptive optics (AO) system....
The 4MOST[1] instrument is a concept for wide-field, fibre-fed high multiplex spectroscopic facility on the ESO VISTA telescope designed to perform massive (initially >25x106 spectra in 5 years) combined all-sky public survey. main science drivers are: Gaia follow up of chemo-dynamical structure Milky Way, stellar radial velocities, parameters and abundances, chemical tagging; eROSITA cosmology with x-ray clusters galaxies, X-ray AGN/galaxy evolution z~5, Galactic sources resolving edge;...
The most relevant basis for designing photovoltaic systems is their annual energy production, which also the best metric monitoring long-term performance. An accurate array performance model based on established testing procedures required to confidently predict available from array. This model, coupled with characteristics of other balance-of-system components, provides tool necessary calculate expected system and compare actual versus production. Using such a tool, this paper quantifies...
Measurements of Zn and Cr abundances in 18 damped Lyα systems (DLAs) at absorption redshifts zabs = 0.692-3.390 (but mostly between ≃ 2 3) show that metals dust are much less abundant high-redshift galaxies than the Milky Way today. Typically, [Zn/H] -1.2; as tracks Fe closely Galactic stars all metallicities is only lightly depleted onto interstellar grains, we conclude overall degree metal enrichment ≈ 13.5 Gyr ago (H0 50 km s-1 Mpc-1, q0 0.05) was ~1/15 solar.
Kappa Andromedae is a B9IVn star at 52 pc for which faint substellar companion separated by 55 AU was recently announced. In this work, we present the first spectrum of companion, "kappa And B," using Project 1640 high-contrast imaging platform. Comparison our low-resolution YJH-band spectra to empirical brown dwarf suggests an early-L spectral type. Fitting synthetic from PHOENIX model atmospheres observed allows us constrain effective temperature ~2000K, as well place constraints on...
We are developing a stable and precise spectrograph for the Large Binocular Telescope (LBT) named "iLocater." The instrument comprises three principal components: cross-dispersed echelle that operates in YJ-bands (0.97-1.30 microns), fiber-injection acquisition camera system, wavelength calibration unit. iLocater will deliver high spectral resolution (R~150,000-240,000) measurements permit novel studies of stellar substellar objects solar neighborhood including extrasolar planets. Unlike...
A multifactor experimental investigation of silicon surface texturing was conducted using aqueous potassium-hydroxide (KOH) solutions with isopropyl alcohol (IPA) added as a complexing agent. Czochralski, magnetic-Czochralski, and float-zone wafers different resistivities both polished lapped surfaces were included in the experiment. Process variables considered solution temperature, time solution, degree mechanical mixing, KOH concentration, IPA concentration. Using hemispherical...
We present astrometric, photometric and spectroscopic observations of supernova 1993J in M8 1, obtained with the Isaac Newton Group telescopes Carlsberg Automatic Meridian Circle. The spectral data set includes first spectrum ever taken SN1993J. early spectra also yield an estimate total visual extinction, |$A_\nu$|. This is combined to produce a bolometric light curve. Implications latter development are discussed. evolution infrared excess, which appeared after day 50 may be indicative IR...
Computer simulation tools used to predict the energy production of photovoltaic systems are needed in order make informed economic decisions. These require input parameters that characterize module performance under various operational and environmental conditions. Depending upon complexity model, required can vary from limited information found on labels affixed modules an extensive set parameters. The normally obtained indoors using a solar simulator or flash tester, measured outdoors...
Project 1640 is a high-contrast imaging instrument recently commissioned at the Palomar observatory. A combination of coronagraph with an integral-field spectrograph (IFS), designed to detect and characterize extrasolar planets, brown dwarfs, circumstellar material orbiting nearby stars. In this paper, we present our data processing techniques for improving upon raw sensitivity via removal quasi-static speckles. Our approach utilizes chromatic image diversity provided by IFS in locally...
In situ X-ray absorption spectroscopy (XAS) results on correlating the Pt local coordination and electronic structure with Pt/C catalyst activity selectivity during aqueous reforming of glycerol at different pH are reported. The show that both low high favor C–O cleavage over C–C. However, toward bond was higher under acidic conditions. XANES measurements reaction conditions showed increased electron density while effect basic minimal. ΔXANES used to estimate coverage adsorbates suggest a...
An electrical simulation model for photovoltaic cells, modules and arrays has been developed that will be useful to a wide range of analysts in the industry. The Microsoft(R) Windows/sup TM/ based program can used analyze individual effects cell mismatch or reverse bias ("hot spot") heating modules, performance large including bypass blocking diodes. User defined statistical variance applied fundamental parameters simulate cells is most appropriate accurately modeled using two-diode...
Rating a PV system is complicated by the difficulties of obtaining performance data under "rating" conditions, intricate relationships between output and prevailing desire for quick results at low cost. Since 1989, PVUSA has been rating systems using continuous collection simple regression model. Sandia National Laboratories developed an improved IV curve-based method characterizing arrays. Several facility in Davis, CA were subjected to both methods. The that work are presented this paper.
Dark current-voltage (dark I-V) measurements are commonly used to analyze the electrical characteristics of solar cells, providing an effective way determine fundamental performance parameters without need for a simulator. The dark I-V measurement procedure does not provide information regarding short-circuit current, but is more sensitive than light in determining other (series resistance, shunt diode factor and saturation currents) that dictate photovoltaic device. work documented here...
Small, low-cost, silicon-photodiode pyranometers are now widely used for solar irradiance measurements associated with thermal and photovoltaic power systems, as well agricultural applications. Without correction, the values indicated by these may differ from "true" broadband over 10%. This paper identifies time-of-day dependent factors responsible systematic errors describes new procedures that effectively compensate influences. Application of should improve calibration methods accuracy...