Crawl space assisted heat pump

A variety of experiments and simulations, currently being designed or underway, to determine the feasibility of conditioning the source air of an air to air heat pump using stored ground heat or cool to produce higher seasonal COP's and net energy savings are discussed. The ground would condition ambient air as it is drawn through the crawl space of a house. Tests designed to evaluate the feasibility of the concept, to determine the amount of heat or cool available from the ground, to study the effect of the system on the heating and cooling loads of the house, to study possible mechanisms which could enhance heat flow through the ground, and to determine if diurnal temperature swings are necessary to achieve successful system performance are described

Exploring the phase diagram of the two-impurity Kondo problem

A system of two exchange-coupled Kondo impurities in a magnetic field gives rise to a rich phase space hosting a multitude of correlated phenomena. Magnetic atoms on surfaces probed through scanning tunnelling microscopy provide an excellent platform to investigate coupled impurities, but typical high Kondo temperatures prevent field-dependent studies from being performed, rendering large parts of the phase space inaccessible. We present an integral study of pairs of Co atoms on insulating Cu2N/Cu(100), which each have a Kondo temperature of only 2.6 K. In order to cover the different regions of the phase space, the pairs are designed to have interaction strengths similar to the Kondo temperature. By applying a sufficiently strong magnetic field, we are able to access a new phase in which the two coupled impurities are simultaneously screened. Comparison of differential conductance spectra taken on the atoms to simulated curves, calculated using a third order transport model, allows us to independently determine the degree of Kondo screening in each phase.Comment: paper: 14 pages, 4 figures; supplementary: 3 pages, 1 figure, 1 tabl

Many-particle effects in adsorbed magnetic atoms with easy-axis anisotropy: the case of Fe on CuN/Cu(100) surface

We study the effects of the exchange interaction between an adsorbed magnetic atom with easy-axis magnetic anisotropy and the conduction-band electrons from the substrate. We model the system using an anisotropic Kondo model and we compute the impurity spectral function which is related to the differential conductance (dI/dV) spectra measured using a scanning tunneling microscope. To make contact with the known experimental results for iron atoms on the CuN/Cu(100) surface [Hirjibehedin et al., Science {\bf 317}, 1199 (2007)], we calculated the spectral functions in the presence of an external magnetic field of varying strength applied along all three spatial directions. It is possible to establish an upper bound on the coupling constant J: in the range of the magnetic fields for which the experimental results are currently known (up to 7T), the low-energy features in the calculated spectra agree well with the measured dI/dV spectra if the exchange coupling constant J is at most half as large as that for cobalt atoms on the same surface. We show that for even higher magnetic field (between 8 and 9T) applied along the ``hollow direction'', the impurity energy states cross, giving rise to a Kondo effect which takes the form of a zero-bias resonance. The paper introduces an approach for calculating the expectation values of global spin operators and all components of the impurity magnetic susceptibility tensor in numerical renormalization group (NRG) calculations with no spin symmetry. An appendix contains a density-functional-theory (DFT) study of the Cu and Fe adsorbates on CuN/Cu(100) surface: we compare magnetic moments, as well as orbital energies, occupancies, centers, and spreads by calculating the maximally localized Wannier orbitals of the adsorbates.Comment: 18 pages, 7 figure

Comment on "Fano Resonance for Anderson Impurity Systems"

In a recent Letter, Luo et al. (Phys. Rev. Lett. 92, 256602 (2004)) analyze the Fano line shapes obtained from scanning tunneling spectroscopy (STS) of transition metal impurities on a simple metal surface, in particular of the Ti/Au(111) and Ti/Ag(100) systems. As the key point of their analysis, they claim that there is not only a Fano interference effect between the impurity d-orbital and the conduction electron continuum, as derived in Ujsaghy et al. (Phys. Rev. Lett. 85, 2557 (2000)), but that the Kondo resonance in the d-electron spectral density has by itself a second Fano line shape, leading to the experimentally observed spectra. In the present note we point out that this analysis is conceptually incorrect. Therefore, the quantitative agreement of the fitted theoretical spectra with the experimental results is meaningless.Comment: 1 page, no figures. Accepted for publication in PRL; revised version uploaded on November 18th, 200

Um modelo determinístico para avaliação do controle biológico de praga de citros.

O objetivo desse trabalho é apresentar um modelo matemático compartimental e determinístico para analisar a dinâmica populacional do inseto-praga Phyllocnistis citrella em interação com seus inimigos naturais Galeopsomyia fausta (parasito nativo) e Ageniaspis citricola (parasito exótico). Com o estudo analítico do sistema de equações diferenciais que descreve o modelo, avalia-se a eficiência do controle biológico da P.citrella através da possibilidade de coexistência entre as espécies e da competição entre os dois inimigos naturais.bitstream/CNPTIA/9955/1/bolpesq3.pdfAcesso em: 28 maio 2008

Uma aplicação do SOC na estimação por intervalo do parametro razão de produtos cruzados em tabelas de contingência 2 x 2.

Neste sentido, foi desenvolvido o programa TAB2x2.ENT utilizando os recursos do módulo CM do SOC - Fevereiro/88, o qual fornece, para dados não pareados dispostos em uma tabela 2x2, as estimativas pontuais do parâmetro razão de produtos cruzados, os limites dos intervalos assintáticos de Cornfield (1956) , Ccx (1958) , Wolf (1954) com correção de continuidade e Gart (1962) , comprimento dos intervalos e, para os métodos assintáticos condicionais, os níveis de significância exatos unicaudais e os coeficientes de confiança exatos.bitstream/item/76611/1/CNPTIA-COM.TEC.-8803-88.pd

Status of neutrino oscillations 2018: first hint for normal mass ordering and improved CP sensitivity

We present a new global fit of neutrino oscillation parameters within the simplest three-neutrino picture, including new data which appeared since our previous analysis~\cite{Forero:2014bxa}. In this update we include new long-baseline neutrino data involving the antineutrino channel in T2K, as well as new data in the neutrino channel, data from NO$\nu$A, as well as new reactor data, such as the Daya Bay 1230 days electron antineutrino disappearance spectrum data and the 1500 live days prompt spectrum from RENO, as well as new Double Chooz data. We also include atmospheric neutrino data from the IceCube DeepCore and ANTARES neutrino telescopes and from Super-Kamiokande. Finally, we also update our solar oscillation analysis by including the 2055-day day/night spectrum from the fourth phase of the Super-Kamiokande experiment. With the new data we find a preference for the atmospheric angle in the upper octant for both neutrino mass orderings, with maximal mixing allowed at $\Delta\chi^2 = 1.6 \, (3.2)$ for normal (inverted) ordering. We also obtain a strong preference for values of the CP phase $\delta$ in the range $[\pi,2\pi]$, excluding values close to $\pi/2$ at more than 4$\sigma$. More remarkably, our global analysis shows for the first time hints in favour of the normal mass ordering over the inverted one at more than 3$\sigma$. We discuss in detail the origin of the mass ordering, CP violation and octant sensitivities, analyzing the interplay among the different neutrino data samples.Comment: Updated neutrino oscillation analysis using the most recent results from T2K, NO$\nu$A, RENO and Super-Kamiokande. 17 pages, 8 figures, 1 tabl

Uso do SOC na análise de modelos lineares multivariados.

bitstream/item/76201/1/CNPTIA-COM.TEC.-8805-88.pd

Desenvolvimento de modelos de regressão como contribuição para a análise de risco de resíduos de pesticidas em maçã.

O Plano Nacional de Controle de Resíduos e Contaminantes (PNCRC) do Ministério da Agricultura Pecuária e Abastecimento (MAPA) é um programa federal de fiscalização de alimentos que visa quantificar resíduos químicos potencialmente nocivos à saúde do consumidor. Os dados coletados pelo PNCRC provêm de uma amostragem homogênea e aleatória, em âmbito nacional, de diversos produtos de origem vegetal e animal, seguida de análises em laboratórios oficiais e credenciados pelo MAPA. Este trabalho objetiva o tratamento dos dados gerados pelo PNCRC, coletados no período de 2008 a 2011, relativos à análise de risco de resíduos de pesticidas em maçã, visando evidenciar correlações espaço-temporais relevantes quanto à concentração de diferentes resíduos químicos.CIIC 2014. Nº 14604

Guidelines for Retrofit Performance Monitoring

A data specification guideline developed for use in the U.S. Department of Energy (DOE) Single-Family Building Energy Retrofit Research Program is applicable to field monitoring studies of cooling retrofits. The guideline was developed to promote the collection of data (more detailed than billing data) that are needed to fully understand retrofit energy performance. The guideline identifies the important data parameters that should be collected to meet this need and defines the data parameters to ensure that consistent and comparable data' are collected. The purpose of this paper is (a) to summarize the data parameters identified in the guideline. and (b) to discuss low-cost instrumentation that can be used to' monitor the data parameters identified in a minimum data set