3,566 research outputs found
Using 4D BIM in the Retrofit Process of Social Housing
There is a large stock of solid wall homes in the UK presenting poor thermal insulation and low energy performance. Although the UK Government has supported improvement efforts in the area, the identification of appropriate technical solutions that effectively improve the existing stock remains a challenge. BIM offers opportunities for building performance optimisation, through improved design and simulation. This research investigates how BIM could improve the retrofit process for social housing. This paper describes a research project looking into the use of BIM to develop what-if scenarios for retrofitting existing âno-finesâ solid wall homes. The scenarios enable the analysis of alternative solutions considering costs, energy performance and user disruption. More specifically, this paper focuses on the use of 4D models to evaluate disruption for end users. The research process includes simulations, meetings, interviews, documents, and observations. Results indicate that the development of 4D BIM models supports a better understanding of the retrofitting process on site, enabling the definition of production processes with as minimal disruption as possible for users, whilst still delivering energy-oriented and cost effective solutions
Approximation for single-channel multi-server queues and queuing networks with generally distributed inter-arrival and service times
This dissertation is divided into two papers. The first paper is related to developing a closed-form approximation for single-channel multiple-server queues with generally distributed inter-arrival and service times, which are often found in numerous settings, e.g., airports and manufacturing systems. Unfortunately, exact models for such systems require distributions for the underlying random variables. Further, data for fitting distributions is sometimes not available, and one only has access to means and variances of the underlying input random variables. Under heavy traffic, excellent approximations already exist for this purpose. In the first paper, a new approximation method for medium traffic is presented. Encouraging numerical evidence for gamma distributed inter-arrival times, often found in many settings, and double-tapering distributions, such as normal, triangular, and gamma, for the service time, is found with the new approximation. In the second paper, a new approximation technique is studied for modeling a two-stage queueing network (QN) in which the first stage contains a multiple-server (G/G/k) queue and the second is composed of multiple single-server queues (G/G/1) in parallel. Airport terminals and other service areas, such as sports stadiums and manufacturing systems, are examples of systems where such two-stage QNs are encountered. The new approximation is rooted in approximating the variance of the service time in a G/G/k queue and leads to encouraging numerical behavior --Abstract, page iv
Characterizing filaments harboring high-mass star formation
MĂ ster Oficial d'AstrofĂsica, FĂsica de PartĂcules i Cosmologia, Facultat de FĂsica, Universitat de Barcelona, Curs: 2016-2017, Tutors: Gemma Busquet, Robert EstalellaA distinguished kind of molecular clouds, the infrared dark clouds (hereafter IRDCs), are
believed to be relevant for describing the initial conditions for high-mass star formation. They are characterized by their lack of detectable emission in the mid-infrared: they appear as a dark silhouette against the corresponding mid-infrared background. IRDCs were first recognized in images from the Infrared Space Observatory (ISO, Egan et al. 1998) and the Midcourse Space Experiment (MSX, Perault et al. 1996
The influence of shearâvelocity heterogeneity on ScS2/ScS amplitude ratios and estimates of Q in the mantle
Regional waveforms of deepâfocus TongaâFiji earthquakes indicate anomalous traveltime differences (ScS2âScS) and amplitude ratios (ScS2/ScS) of the phases ScS and ScS2. The correlation between the ScS2âScS delay time and the ScS2/ScS amplitude ratio suggests that shear wave apparent Q in the mantle below the TongaâFiji region is highest when shear wave velocities are lowest. This observation is unexpected if temperature variations were responsible for the seismic anomalies. Using spectral element method waveform simulations for four tomographic models, we demonstrate that focusing and scattering of shear waves by longâwavelength 3âD heterogeneity in the mantle may overwhelm the signal from intrinsic attenuation in longâperiod ScS2/ScS amplitude ratios. The tomographic models reproduce the trends in recorded ScS2âScS difference times and ScS2/ScS amplitude ratios. Although they cannot be ruled out, variations in shear wave attenuation (i.e., the quality factor Q) are not necessary to explain the data.Key PointsThe influence of complex 3âD wave propagation in the mantle on ScS2/ScS amplitude ratiosScS2âScS difference times are delayed and ScS2/ScS amplitude ratios are high on Samoa indicating low wave speeds but no attenuationBody wave amplitudes may be useful for evaluating the accuracy of tomographic models and as complementary data in tomographic inversionsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134191/1/grl54786_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134191/2/grl54786.pd
TOWARDS A NATIONAL INNOVATION FRAMEWORK FOR AGRICULTURAL SCIENCE AGENCIES IN EMERGING ECONOMIES
N° ISBN - 978-2-7380-1284-5International audienceThe national science agencies have had a great role in the context of emerging economies catching-up. This paper addresses the search to a better understanding of strategies for emerging economies whose agricultural sector is a key economic area. The paper presents the context of the emerging economies, noting briefly some of the factors about their agricultural R&D; introduces the concept of a national innovation framework and outlines some insights from the NAIS (national agricultural innovation system). Additionally, the paper will offer a framework for these countries to select and adapt data sets, tools and methodologies needed to assist policy decision makers as they want to invest in national agricultural R&D. This theoretical essay's key contribution is conceptual and methodological: the development of a framework towards a more evidence-based understanding of what happens to given R&D investments. The applied framework is used in the analysis of the innovativeness and success of past investments that have succeeded, which can help policymakers to develop sound and cost-effective investment strategies, and also mapping the loci were they should apply metrics and evaluations to guide their agricultural science policy decisions. This could be useful as an analytical tool and as a tool for promoting sustainable economic growth and well-being in the emerging economies
Validação das escalas de evitação e ansiedade social e temor à avaliação negativa em população colombiana
Esta investigaciĂłn tuvo como propĂłsito la validaciĂłn en poblaciĂłn colombiana de la Escala de Temor a la EvaluaciĂłn Negativa (FNE) que evalĂșa el grado en que las personas experimentan temor ante la posibilidad de ser juzgadas negativamente, y la Escala de EvitaciĂłn y Ansiedad Social (SAD) que evalĂșa el malestar subjetivo, la evitaciĂłn activa o los deseos de escape que experimentan las personas con fobia social. En total fueron 471 participantes de ambos sexos, de diferentes estratos socioeconĂłmicos y niveles educativos. El muestreo fue aleatorio polietĂĄpico por conglomerados. Se encontrĂł que el SAD tiene un alfa de 0,85, pero el FNE obtuvo un alfa de 0,66. Este Ășltimo resultado suscitĂł el anĂĄlisis de los problemas de confiabilidad relacionados con los Ătems inversos, dicotĂłmicos y el nivel de escolaridad de los participantes. Se sugiere que los instrumentos de evaluaciĂłn psicomĂ©trica utilicen escalas Likert y eviten la inclusiĂłn de Ătems invertidos.O objetivo desta pesquisa foi a validação em população colombiana da Escala de Temor Ă Avaliação Negativa (FNE), que avalia o grau de temor experimentado pelas pessoas ante a possibilidade de ser julgadas negativamente, e a Escala de Evitação e Ansiedade Social (SAD), que avalia o mal-estar subjetivo, a evitação ativa ou os desejos de evasĂŁo experimentados pelas pessoas com fobia social. Participaram 471 homens e mulheres de diversos estratos socioeconĂŽmicos e nĂveis educativos. A amostra foi aleatĂłria, em vĂĄrias etapas, por conglomerados. Achou-se que o SAD tem um alfa de 0.85; enquanto o FNE teve um alfa de 0.66. Este resultado provocou a anĂĄlise dos problemas de confiabilidade, relacionados com os itens inversos, dicotĂŽmicos e o nĂvel de escolaridade dos participantes. Ă sugerido que os instrumentos de avaliação psicomĂ©trica usem escalas Likert e evitem a inclusĂŁo de itens invertidos.This research had the purpose of validating the Negative Fear Evaluation Scale (FNE) in Colombian population. The FNE evaluates the degree in which people experiment fear about the possibility of others judging them negatively. Likewise, this research had the purpose of validating the Social Avoidance and Distress Scale (SAD) that evaluates the subjective distress, the active avoidance or the escape desires that people with social phobia experiment. There were 471 participants of both genders, representing different social classes and educational levels. The sampling procedure was carried out at random, involved several stages and was done by conglomerates. It was found that the SAD scale showed an alpha of 0.85, whereas the FNE showed an alpha 0.66. This result raises the need to analyze reliability problems related to dichotomic inverse items and the educational level of the participants. The study suggests that psychometric evaluation instruments should use Likert scales and avoid the inclusion of reverse items
"Chroniques de la RĂ©volution" o cuando las redes sociales son fuente de inspiraciĂłn de documentales
Chroniques de la RĂ©volution es el segundo largometraje documental del director tunecino Habib Mestiri, realizado en 2012. Su originalidad radica en que los protagonistas son, ademĂĄs de personajes famosos nacidos en TĂșnez como Claudia Cardinale, Georges Wolinski o Michel Bounejah, niños y adolescentes que realizan cortometrajes sobre la RevoluciĂłn tunecina a partir de imĂĄgenes que han visto y compartido en las redes sociales, especialmente en Facebook. Es la primera vez que se le da voz a los niños para que cuenten cĂłmo vivieron ellos la RevoluciĂłn y quĂ© futuro esperan tras la misma. Compartir informaciĂłn es uno de los principales motivos por los que se creĂł Internet y la bĂșsqueda de esa informaciĂłn la razĂłn por la que diariamente lo consultamos. Gracias a la uniĂłn de los principios de Internet y la cinematografĂa se ha conseguido realizar este documental, que se hibrida con otros gĂ©neros como el cortometraje o el videoactivismo. Gracias a este documental podemos entender la importancia que tuvieron las redes sociales a la hora de difundir los acontecimientos que tuvieron lugar durante los dĂas que durĂł la RevoluciĂłn tunecina. A pesar de su importancia es necesario recordar que no se ha tratado en ningĂșn momento de una ârevoluciĂłn Facebookâ sino que las redes sociales han sido Ășnicamente el medio a travĂ©s del cual compartir y consultar informaciĂłn y en el que los mensajes se han reproducido mĂĄs rĂĄpidamente
Double-Recurrence Fibonacci Numbers and Generalizations
Let be the Fibonacci sequence given by the recurrence
, for , where and . There are
several generalizations of this sequence and also several interesting
identities. In this paper, we investigate a homogeneous recurrence relation
that, in a way, extends the linear recurrence of the Fibonacci sequence for two
variables, called {\it double-recurrence Fibonacci numbers}, given by , for , where , , and . We exhibit a formula
to calculate the values of this double recurrence, only in terms of Fibonacci
numbers, such as certain identities for their sums are outlined. Finally, a
general case is studied.Comment: 10 pages, 5 figures and 1 tabl
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