Dynamic Time-history Analysis on Wind-induced Response of Light-weight Roof System

Severe damage to light-weight roof system occur when exposed to strong wind loading. Damage investigations and wind load-bearing capacity tests of light-weight roof system reveal that the connection damage of roof sheeting and fastener is the most serious. Wind pressure distributions on the roof of gabled steel frame measured in a wind tunnel are described. Secondly, illustrated by the example of the classic standing-lock roof system, the wind-induced forces for the concealed clips estimated by the building code and time-history analysis based on wind tunnel test, respectively, are compared. The results indicate that the uniform gust factor used in the building code for the wind-induced forces for the clips cannot guarantee that all the clips have strong strength in an actual wind load. Any of wind-induced forces for the clips varies in a relative large rang affected by the fluctuation and spatial correlation of wind pressure. The building code generally provided inconsistent estimations of the wind-induced forces of the clips and the true loaded wind area should be evaluated by considering the characteristics of the spatial correlation of wind pressures relative to the structural framing

Photometric properties and luminosity function of nearby massive early-type galaxies

We perform photometric analyses for a bright early-type galaxy (ETG) sample with 2949 galaxies ($M_{\rm r}<-22.5$ mag) in the redshift range of 0.05 to 0.15, drawn from the SDSS DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian and isophotal magnitudes, as well as the corresponding half-light radius for each galaxy. We find that for brightest galaxies ($M_{\rm r}<-23$ mag), our Petrosian magnitudes, and isophotal magnitudes to 25 ${\rm mag/arcsec^2}$ and 1\% of the sky brightness are on average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. Similarly, the typical half-light radii ($r_{50}$) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright-end of the $r$-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al. (2003), and the stellar mass densities at $M_{\ast}\sim 5\times10^{11} M_{\odot}$ and $M_{\ast}\sim 10^{12} M_{\odot}$ are a few tenths and a factor of few higher than those of Bernardi et al. (2010). These results may significantly alleviate the tension in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model.Comment: 43 pages, 14 figures, version accepted for publication in the Astrophysical Journa

Coherent population trapping in a dressed two-level atom via a bichromatic field

We show theoretically that by applying a bichromatic electromagnetic field, the dressed states of a monochromatically driven two-level atom can be pumped into a coherent superposition termed as dressed-state coherent population trapping. Such effect can be viewed as a new doorknob to manipulate a two-level system via its control over dressed-state populations. Application of this effect in the precision measurement of Rabi frequency, the unexpected population inversion and lasing without inversion are discussed to demonstrate such controllability.Comment: 14 pages, 6 figure

Nonorthogonal decoy-state Quantum Key Distribution

In practical quantum key distribution (QKD), weak coherent states as the photon sources have a limit in secure key rate and transmission distance because of the existence of multiphoton pulses and heavy loss in transmission line. Decoy states method and nonorthogonal encoding protocol are two important weapons to combat these effects. Here, we combine these two methods and propose a efficient method that can substantially improve the performance of QKD. We find a 79 km increase in transmission distance over the prior record using decoy states method.Comment: 4 pages, 1 figure; Revtex4, submitted to PR

Quantum broadcast communication

Broadcast encryption allows the sender to securely distribute his/her secret to a dynamically changing group of users over a broadcast channel. In this paper, we just consider a simple broadcast communication task in quantum scenario, which the central party broadcasts his secret to multi-receiver via quantum channel. We present three quantum broadcast communication schemes. The first scheme utilizes entanglement swapping and Greenberger-Horne-Zeilinger state to realize a task that the central party broadcasts his secret to a group of receivers who share a group key with him. In the second scheme, based on dense coding, the central party broadcasts the secret to multi-receiver who share each of their authentication key with him. The third scheme is a quantum broadcast communication scheme with quantum encryption, which the central party can broadcast the secret to any subset of the legal receivers

Object Picture of Quasinormal Modes for Stringy Black Holes

We study the quasinormal modes (QNMs) for stringy black holes. By using numerical calculation, the relations between the QNMs and the parameters of black holes are minutely shown. For (1+1)-dimensional stringy black hole, the real part of the quasinormal frequency increases and the imaginary part of the quasinormal frequency decreases as the mass of the black hole increases. Furthermore, the dependence of the QNMs on the charge of the black hole and the flatness parameter is also illustrated. For (1+3)-dimensional stringy black hole, increasing either the event horizon or the multipole index, the real part of the quasinormal frequency decreases. The imaginary part of the quasinormal frequency increases no matter whether the event horizon is increased or the multipole index is decreased.Comment: 4 pages, 5 figure

A América Latina na política externa brasileira: um balanço dos governos petistas (2003-2016)

Dissertação apresentada ao Programa de Pós-Graduação em Integração Contemporânea da América Latina da Universidade Federal da Integração Latino-Americana, como requisito parcial à obtenção do título de Mestra em Integração Latino-Americana. Orientadora: Profa. Dra. Renata Peixoto de OliveiraNo início do século XXI, governos de esquerda e centro-esquerda surgiram na América Latina e, assim, Luiz Inácio Lula da Silva é eleito Presidente da República no Brasil, em 2002. Neste contexto, a política externa brasileira é reformulada e colocada em evidência, tornando o país um importante ator das relações internacionais. O Brasil aprofunda as relações Sul-Sul e dentro deste movimento encontra-se uma nova perspectiva sobre a relação com a América Latina, com a criação de novas instituições e ênfases para a integração. Quando assume Dilma Rousseff, em 2011, há a manutenção das diretrizes gerais da PEB - ainda que tenham ocorrido mudanças no contexto internacional e no papel do Brasil, bem como a modificação das figuras-chave da sua política exterior e impasses domésticos. Tais mudanças irão causar uma alteração no comportamento internacional brasileiro. Desta forma, esta pesquisa tem o objetivo de investigar qual foi a política externa que o Brasil implementou para a América Latina durante os governos petistas (2003-2016), as principais diferenças em relação aos períodos anteriores e entre estes dois governos, e se houve aplicação de ideias do partido na condução externa do país. Para esta análise, será feita uma revisão bibliográfica de artigos e livros sobre a temática, assim como de documentos oficiais do Itamaraty, da Presidência da República Federativa do Brasil, do PT, de instituições de integração regional e discursos, com o intuito de avaliarmos a posição brasileira e as relações com a região. Isto posto, o trabalho se dividirá em quatro partes: na primeira, poderemos ter um histórico das relações do Brasil com o continente, desde a gestão do Barão do Rio Branco - patrono da diplomacia brasileira - até o governo FHC; na segunda parte, temos uma investigação sobre o PT e o seu pensamento de política internacional e externa; nos dois capítulos finais, será feito um estudo específico sobre o governo Lula e Dilma.En el inicio del siglo XXI, gobiernos izquierda y centroizquierda surgieron enAmérica Latina y, así, Luiz Inácio Lula da Silva fue elegido Presidente de la Repúblicade Brasil, en 2002. En este contexto, la política exterior brasileña es reformulada ypuesta en evidencia, haciendo del país un importante actor de las relacionesinternacionales. Brasil profundiza las relaciones Sur-Sur y dentro de este movimientose encuentra una nueva perspectiva sobre las relaciones con América Latina, con lacreación de nuevas instituciones y énfasis para la integración. Con la llegada de DilmaRousseff, en 2011, hay el mantenimiento de las directrices generales de la PEB,aunque haya ocurrido cambios en el contexto internacional y el papel de Brasil,modificación de las figuras clave de su política exterior y problemas domésticos. Estoscambios causaron una modificación en el comportamiento internacional brasileño. Deesta forma, esta investigación tiene el objetivo de investigar cuál fue la política externaque Brasil implementó para América Latina durante los gobiernos petistas (2003-2016),las principales diferencias en relación a los períodos anteriores y entre estos dosgobiernos y si hubo aplicación de ideas del partido en la conducción externa del país.Para este análisis, se hará una revisión bibliográfica de artículos y libros sobre latemática, así como de documentos oficiales de Itamaraty, de la Presidencia de laRepública Federativa del Brasil, del PT, de instituciones de integración regional ydiscursos, para evaluar la posición brasileña y las relaciones con la región. El trabajose dividirá en cuatro partes: en la primera, podremos tener un histórico de lasrelaciones de Brasil con el continente, desde la gestión del Barón de Río Branco -patrono de la diplomacia brasileña - hasta el gobierno FHC; en la segunda parte,tenemos una investigación sobre el PT y su pensamiento de política internacional ypolítica exterior, mientras que un estudio específico sobre el gobierno de Lula y Dilmasera hecho en los dos capítulos finale

Active Spoofing Attack Detection:An Eigenvalue Distribution and Forecasting Approach

Physical-layer security has drawn ever-increasing attention in the next generation wireless communications. In this paper, we focus on studying the secure communication in an HPN-to-devices (HTD) network, in which a new type of MAC spoofing attack is considered. To detect the malicious attack, we propose a novel algorithm, namely, eigenvalue test using random matrix theory (ETRMT) algorithm, which needs no prior information about the channel. In particular, when the number of samples is finite at the receiver or the number of devices is large, the sampled signal is the biased estimation of the actual signal, which inspires us to use the random matrix theory to analyze the spoofing attack detection. The closed-form expressions of the detection probability, the false alarm probability, and the Neyman-Pearson threshold are derived based on eigenvalue distribution of the spiked population model. In addition, taking the channel time-varying into consideration, we provide an adaptive threshold tracking method by using Bayesian forecasting. Finally, the simulations are conducted to validate our proposed method and some insightful conclusions are obtained