Development of a Multi-Family Water Conservation Project Tool

Indiana University Purdue University IndianapolisIn order for building operations to be successful long-term, the building must perform well and meet the needs of the occupants in a safe, cost effective manner. Utility costs, especially water costs, impact the performance of the building. Effective water conservation programs can significantly reduce operational costs. Designing and implementing an effective water conservation program for use in multi-family residences throughout a large portfolio poses a number of challenges that impact the success of the water conservation effort. Establishing a targeted program designed to deliver substantial savings requires a strong methodology. Without such methods, the program could be ineffective or fall short and therefore not be sustainable. To encourage conservation, many federal and state agencies as well as local utilities are providing guidance and incentives for water conservation. The agencies push for conservation to reduce demand for potable water and the need for infrastructure expansions. For the end user, the need for conservation is driven by the cost impacts associated with usage and rates. Water conservation reduces these impacts. The purpose of this project is to construct a program and tool to be utilized by the multi-family facility manager providing the framework and methodology for creating a sustainable water conservation program specific to her portfolio. The key deliverables are: a written guide explaining the components of a robust water conservation program, an Excel tool for use in estimating the project’s return on investment (ROI) and a demonstration of the tool using data from a typical multi-family structure. This tool will be based on real world experience with implementing water conservation efforts across a national footprint of buildings and will be geared toward the typical industry demands of simple installations and measurable water reductions with a high rate of return in a short time-frame.Facilities Management Technolog

Fowler-Nordheim-like local injection of photoelectrons from a silicon tip

Tunneling between a photo-excited p-type silicon tip and a gold surface is studied as a function of tip bias, tip/sample distance and light intensity. In order to extend the range of application of future spin injection experiments, the measurements are carried out under nitrogen gas at room temperature. It is found that while tunneling of valence band electrons is described by a standard process between the semiconductor valence band and the metal, the tunneling of photoelectrons obeys a Fowler-Nordheim-like process directly from the conduction band. In the latter case, the bias dependence of the photocurrent as a function of distance is in agreement with theoretical predictions which include image charge effects. Quantitative analysis of the bias dependence of the dark and photocurrent spectra gives reasonable values for the distance, and for the tip and metal work functions. For small distances image charge effects induce a vanishing of the barrier and the bias dependence of the photocurrent is exponential. In common with many works on field emission, fluctuations in the tunneling currents are observed. These are mainly attributed to changes in the prefactor for the tunneling photocurrent, which we suggest is caused by an electric-field-induced modification of the thickness of the natural oxide layer covering the tip apex.Comment: 12 pages, 11 figures. Submitted to Phys. Rev.

Electronic properties of GaAs surfaces etched in an electron cyclotron resonance source and chemically passivated using P2S5P2S5

Photoreflectance has been used to study the electronic properties of (100) GaAs surfaces exposed to a Cl2/ArCl2/Ar plasma generated by an electron cyclotron resonance source and subsequently passivated by P2S5.P2S5. The plasma etch shifts the Fermi level of p-GaAsp-GaAs from near the valence band to midgap, but has no effect on n-GaAs.n-GaAs. For ion energies below 250 eV, post-etch P2S5P2S5 chemical passivation removes the surface etch damage and restores the electronic properties to pre-etch conditions. Above 250 eV, the etch produces subsurface defects which cannot be chemically passivated. Auger electron spectroscopy shows that etching increases As at the GaAs/oxide interface, while passivation reduces it. © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69373/2/APPLAB-73-1-114-1.pd

Electroreflectance spectroscopy in self-assembled quantum dots: lens symmetry

Modulated electroreflectance spectroscopy $\Delta R/R$ of semiconductor self-assembled quantum dots is investigated. The structure is modeled as dots with lens shape geometry and circular cross section. A microscopic description of the electroreflectance spectrum and optical response in terms of an external electric field (${\bf F}$) and lens geometry have been considered. The field and lens symmetry dependence of all experimental parameters involved in the $\Delta R/R$ spectrum have been considered. Using the effective mass formalism the energies and the electronic states as a function of ${\bf F}$ and dot parameters are calculated. Also, in the framework of the strongly confined regime general expressions for the excitonic binding energies are reported. Optical selection rules are derived in the cases of the light wave vector perpendicular and parallel to $$. Detailed calculation of the Seraphin coefficients and electroreflectance spectrum are performed for the InAs and CdSe nanostructures. Calculations show good agreement with measurements recently performed on CdSe/ZnSe when statistical distribution on size is considered, explaining the main observed characteristic in the electroreflectance spectra

Comparación entre datos de temperatura del mar estimados mediante el sensor AVHRR y registros in situ en el golfo San Matías (Patagonia, Argentina)

In situ records of sea surface temperature collected between 2005 and 2009 were used to compare, for the first time, the temperature estima ted by the Multichannel algorithms (MCSST) of the Advanced Very High Resolution Radiometer (AVHRR) sensors in San Matías Gulf, in the north of the Argentinean Patagonian Continental Shelf (between 40º47'-42º13'S). Match-ups between in situ records and satellite sea surface temperature (SST) were analyzed. In situ records came from fixed stations and oceanographic cruises, while satellite data came from di fferent NOAA satellites. The fitting of temperature data to a Standard Major Axis (SMA) type II regression model indicated that a high proportion of the total variance (0.53 ≤ r 2 ≤ 0.99) was explained by this model showing a high correlation between in situ data and satellite estimations. The mean differences between satellite and in situ data for the full data set were 1.64 ± 1.49ºC. Looking separately into in situ data from different sources and day and night estimates from different NOAA satellites, the differences were between 0.30 ± 0.60°C and 2.60 ± 1.50°C. In this paper we discuss possible reasons for the above-mentioned performan ce of the MCSST algorithms in the study area.Se utilizaron mediciones de campo de temperatura del mar realizadas entre 2005 y 2009 para comparar, por primera vez, las esti maciones de los algoritmos Multicanal de temperatura (MCSST) del sensor Advanced Very High Resolution Radiometer (AVHRR) en el golfo San Matías, norte de la plataforma continental Argentina patagónica (40º47'-42º13'S). Se analizaron diferentes pares de datos considerando registros in situ de estaciones fijas y oceanográficas y estimaciones diurnas y nocturnas de temperatura superficial (TSM) de diferentes saté lites NOAA. Se ajustaron los datos a un modelo de regresión Standard Major Axis (SMA) tipo II el cual explicó una alta proporción de la varianza total (0,53 ≤ r 2 ≤ 0,99). La diferencias medias entre los datos satelitales e in situ para todo el conjunto de datos fue de 1,64 ± 1,49ºC, al discriminar entre diferentes fuentes de datos in situ , y estimaciones diurnas y nocturnas de diferentes satélites NOAA, las diferencias medias variaron entre 0,30 ± 0,60ºC y 2,60 ± 1,50ºC. En este trabajo se discuten las posibles razones que explican el desempeño de los algoritmos MCSST en el área de estudio.Fil: Williams, Gabriela Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Zaidman, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; Argentina. Provincia de Chubut. Secretaría de Ciencia, Tecnología e Innovación Productiva; ArgentinaFil: Glembocki, Nora Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Narvarte, Maite Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; ArgentinaFil: González, Raul Alberto Candido. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; ArgentinaFil: Esteves, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Gagliardini, Domingo Antonio. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

Optical Properties of Gallium-Doped Zinc Oxide-A Low-Loss Plasmonic Material: First-Principles Theory and Experiment

Searching for better materials for plasmonic and metamaterial applications is an inverse design problem where theoretical studies are necessary. Using basic models of impurity doping in semiconductors, transparent conducting oxides (TCOs) are identified as low-loss plasmonic materials in the near-infrared wavelength range. A more sophisticated theoretical study would help not only to improve the properties of TCOs but also to design further lower-loss materials. In this study, optical functions of one such TCO, gallium-doped zinc oxide (GZO), are studied both experimentally and by first-principles density-functional calculations. Pulsed-laser-deposited GZO films are studied by the x-ray diffraction and generalized spectroscopic ellipsometry. Theoretical studies are performed by the total-energy-minimization method for the equilibrium atomic structure of GZO and random phase approximation with the quasiparticle gap correction. Plasma excitation effects are also included for optical functions. This study identifies mechanisms other than doping, such as alloying effects, that significantly influence the optical properties of GZO films. It also indicates that ultraheavy Ga doping of ZnO results in a new alloy material, rather than just degenerately doped ZnO. This work is the first step to achieve a fundamental understanding of the connection between material, structural, and optical properties of highly doped TCOs to tailor those materials for various plasmonic applications

Caracterización de la comunidad fitoplanctónica y espectros de absorción óptica en un sitio costero en el norte del golfo San Jorge

Las aguas costeras próximas a la Isla Pan de Azúcar dentro del Parque Interjurisdiccional Marino Costero Patagonia Austral (PIMCPA), fueron muestreadas en marzo de 2020. En esta región, la distribución del fitoplancton se relaciona con características batimétricas u oceanográficas como cabos, surgencias y áreas frontales que favorecen el ascenso de nutrientes a la capa superior de la columna de agua. Este sector es considerado de gran importancia para la conservación de una gran diversidad de especies marinas y es parte de la Reserva de Biósfera "Patagonia Azul" (UNESCO, 2015). Datos satelitales estándar nivel 3 de clorofila-a y absorción por fitoplancton a 443 nm del sensor MODIS (2003-2020, https://giovanni.gsfc.nasa.gov/), permitieron determinar que en el área de estudio el ciclo del fitoplancton es típico de aguas sin estratificación estacional. Las muestras fueron tomadas en cuatro estaciones de muestreo en una transecta perpendicular a la costa durante el máximo de clorofila-a satelital (≈3,0 mg m-3), ocurrido entre enero-marzo de 2020 (clorofila-a in situ 2,01±1,25 mg m-3). La composición de los principales grupos fitoplanctónicos y sus respectivos espectros de absorción fueron determinadas mediante microscopio invertido y espectrofotómetro, respectivamente. La composición de la comunidad fitoplanctónica fue muy similar en todas las estaciones, observándose una moderada dominancia de diatomeas (entre 28 y 48%) y nanoflagelados (entre 19 y 46%), y en menor proporción dinoflagelados (entre 9 y 33%). La caracterización óptica del material particulado mostró predominio del fitoplancton en la absorción de la luz para esta fracción a 443 nm (60%) y 675 nm (88%). Estos resultados son de importancia en la caracterización bio-ópica del golfo San Jorge, vinculada a la evaluación de algoritmos satelitales de color del mar, así como también en el estudio de la calidad de aguas costeras, fenología del fitoplancton y floraciones algales nocivas, entre otros.Fil: Gracia Villalobos, Leilen Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Nocera, Ariadna Celina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Glembocki, Nora Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Williams, Gabriela Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaXI Jornadas Nacionales de Ciencias del Mar; XIX Coloquio de OceanografíaComodoro RivadaviaArgentinaUniversidad Nacional de la Patagonia San Juan Bosco. Sede Comodoro RivadaviaUniversidad Nacional de la Patagonia San Juan Bosco. Instituto de Desarrollo CosteroConsejo Nacional de Investigaciones Cientificas y Tecnicas. Centro de Investigaciones y Transferencia Golfo San Jorg

Application of photoreflectance to advanced multilayer structures for photovoltaics

Photoreflectance (PR) is a convenient characterization tool able to reveal optoelectronic properties of semiconductor materials and structures. It is a simple non-destructive and contactless technique which can be used in air at room temperature. We will present experimental results of the characterization carried out by means of PR on different types of advanced photovoltaic (PV) structures, including quantum-dot-based prototypes of intermediate band solar cells, quantum-well structures, highly mismatched alloys, and III?V-based multi-junction devices, thereby demonstrating the suitability of PR as a powerful diagnostic tool. Examples will be given to illustrate the value of this spectroscopic technique for PV including (i) the analysis of the PR spectra in search of critical points associated to absorption onsets; (ii) distinguishing signatures related to quantum confinement from those originating from delocalized band states; (iii) determining the intensity of the electric field related to built-in potentials at interfaces according to the Franz?Keldysh (FK) theory; and (v) determining the nature of different oscillatory PR signals among those ascribed to FK-oscillations, interferometric and photorefractive effects. The aim is to attract the interest of researchers in the field of PV to modulation spectroscopies, as they can be helpful in the analysis of their devices

Polarized photoreflectance and photoluminescence spectroscopy of InGaAs/GaAs quantum rods grown with As2 and As4 sources

We report photoreflectance (PR) and photoluminescence (PL) investigations of the electronic and polarization properties of different aspect ratio (height/diameter) InGaAs quantum rods (QRs) embedded in InGaAs quantum wells (QWs). These nanostructures were grown by molecular beam epitaxy using As2 or As4 sources. The impact of the As source on the spectral and polarization features of the QR- and QW-related interband transitions was investigated and explained in terms of the carrier confinement effects caused by variation of composition contrast between the QR material and the surrounding well. Polarized PR and PL measurements reveal that the polarization has a preferential direction along the [ 110] crystal axis with a large optical anisotropy of about 60% in the (001) plane for high aspect ratio (4.1:1) InGaAs QRs. As a result, in PL spectra, the transverse magnetic mode dominated (110)-cleaved surfaces (TM[001] > TE[110]), whereas the transverse electric mode prevailed for (110)-cleaved surfaces (TM[001] < TE[110] ¯ ). This strong optical anisotropy in the (001) plane is interpreted in terms of the hole wavefunction orientation along the [ 110] direction for high aspect ratio QRs