803 research outputs found
Experimental Determination Of Relative Signs Of Dipole Moment Derivatives: Hcn And Dcn
An alternative numerical analysis for the experimental determination of the relative signs of the dipole moment derivatives with respect to the normal coordinates is presented. Use is made of the polar tensor and effective charge equations and the G-intensity sum rule of Crawford. The relative signs are determined by sufficiently accurate individual infrared fundamental intensities of one molecule and only the sum of these intensities for an isotopically related molecule. The intensity data of HCN and DCN are used to illustrate the procedure. The as yet unreported values of the atomic polar tensors and effective charges of these molecules are also reported. © 1978 American Institute of Physics.68384785
F And G Intensity Sum Rule Applications: The Chxd4-x Molecules
Numerical analyses based on the F and G intensity sum rules show that recently published experimental values for the fundamental vibrational intensities of CH4, CH3D, CH2D2, CHD3, and CD4 are internally consistent within experimental errors. Effective charge values for the carbon and hydrogen atoms obtained using the intensity sums for all these isotopically related molecules are almost in exact agreement with reported values obtained from the polar tensors of CH4 and CD4. The G sum rule allows a determination of the signs of the dipole moment derivatives using the fundamental intensity sum for CH4 (or CD4) and the polar tensor values for CD4 (or CH4). © 1978 American Institute of Physics.6994147414
A model to simulate the contribution of fibre reinforcement for the punching resistance of RC slabs
In this paper analytical formulations are developed for the prediction of the punching resistance of flat slabs
17 of steel fibre reinforced concrete (SFRC) flexurally reinforced with steel bars. By performing statistical
18 analysis with a database that collects experimental results on the characterization of the post-cracking
19 behaviour of SFRC, equations are determined for the evaluation of the residual flexural tensile strength
20 parameters (fRi) from fundamental data that characterize steel fibres. The fRi strength parameters proposed by
21 CEB-FIP 2010 were used for the definition of the stress-crack width law (s-w) that simulates the fibre
22 reinforcement mechanisms in cement based materials. In the second part of the paper is described an
2
analytical formulation based on the concepts proposed by Muttoni and Ruiz, where 23 the s-w law is
24 conveniently integrated for the simulation of the contribution of steel fibres for the punching resistance of
25 SFRC slabs. By using a database composed of 154 punching tests with SFRC slabs, the good predictive
26 performance of the developed proposal is demonstrated. The good performance of this model is also
27 evidenced by comparing its predictions to those from other models.Fundação para a Ciência e a Tecnologia (FCT
Economic assesment of neosporosis in beef cattle system performance with different technological levels.
The objective of this study was to determine if there is economic losses caused by neoporosis by identifying the number of abortions occurred in beef cattle in the Pantanal region of Mato Grosso do Sul, which are associated with the disease, and then estimate the economic loss to the productive system. 1098 heifers were evaluated from breeding season to the birth of calves in relation to reproductive performance, and the serological diagnosis of neosporosis was performed. To estimate the economic loss it was chosen the projection of exploratory scenarios through simulation using the software Gerenpec/Embrapa. The output rate for heifers seropositive and seronegative to neosporosis was 28.24% and 50.12% respectively, showing a 44% reduction in the output rate of heifers seropositive to Neospora caninum. The evolution of the herd for a period of 10 years showed higher production of animals in the herd free of disease in three technology levels, with values of 7.3%, 7.1% and 8.7% in stages I, II and III respectively when compared to systems with the disease. By comparing the rate of revenue in the 10 th year of a system free of the disease with an actual observed income over the three levels of technology: the technological level to 14% revenue I, Level II and 21% of revenues to the level technological III 34% higher. Therefore, the study highlights the importance of rural business management geared towards forward-looking vision by identifying trends, behaviors and/or opportunities that will serve as sources for the development of strategic actions, and thus provide increased productivity of rural enterprises eg, methods of neosporosis control using strategies such as the disposal of positive animals
The predictive performance of design models for the punching resistance of SFRC slabs in inner column loading conditions
In the recent years steel fibre reinforced concrete (SFRC), in a volume percentage between 0.75
and 1.25, is being proposed to build slabs supported on piles and slabs supported on columns, where the unique
conventional reinforcement is composed of some steel bars in the alignments of the columns/piles, designated as
anti-progressive collapse bars.
Punching resistance, however, can be a concern in this structural system. In fact, punching has a brittle failure
character, and the prediction of the punching resistance is still a challenge, even in concrete slabs with
traditional reinforcement systems. The difficulties on assessing the contribution of the reinforcement
mechanisms of steel fibres for the flexural and shear resistance in the critical punching perimeter increase this
complexity.
The research carried out in this paper has the purpose of assessing the reliability of existing analytical models
for the prediction of the punching resistance of SFRC slabs. For this purpose, a data-base of experimental tests
with SFRC slabs failing in punching was built and the predictive performance of four analytical available
models was assessed. In order to turn more practical the model that is more reliable from physical and
mechanical point of views, the concepts proposed by Model Code 2010 for the characterization of the postcracking behaviour of FRC were introduced in this model
Gaussian superpositions in scalar-tensor quantum cosmological models
A free scalar field minimally coupled to gravity model is quantized and the
Wheeler-DeWitt equation in minisuperspace is solved analytically, exhibiting
positive and negative frequency modes. The analysis is performed for positive,
negative and zero values of the curvature of the spatial section. Gaussian
superpositions of the modes are constructed, and the quantum bohmian
trajectories are determined in the framework of the Bohm-de Broglie
interpretation of quantum cosmology. Oscillating universes appear in all cases,
but with a characteristic scale of the order of the Planck scale. Bouncing
regular solutions emerge for the flat curvature case. They contract classically
from infinity until a minimum size, where quantum effects become important
acting as repulsive forces avoiding the singularity and creating an
inflationary phase, expanding afterwards to an infinite size, approaching the
classical expansion as long as the scale factor increases. These are
non-singular solutions which are viable models to describe the early Universe.Comment: 14 pages, LaTeX, 3 Postscript figures, uses graficx.st
Evaluation of water and sucrose diffusion coefficients during osmotic dehydration of jenipapo (Genipa americana L.).
The apparent diffusion coefficients for sucrose and water during osmotic dehydration of jenipapos were determined. Long time experiments (up to 60 h) were carried out in order to determine equilibrium concentrations inside jenipapos, whereas short time experiments (up to 4 h) were performed to provide detailed information on kinetics of water loss and solids gain at the beginning of osmotic treatment. According to the result, mass transfer rates for water and solutes, as well as the apparent diffusion coefficients for sucrose showed to be dependent on sucrose concentration in osmotic solution. The immersion time did not have significant effect (p>0.05) over the diffusion coefficients for sucrose and water
Avaliação do cálculo da resistência ao punçoamento centrado de lajes fungiformes reforçadas com fibras de aço : modelos teóricos
Desde 1979 que as fibras de aço vêm sendo estudadas como uma alternativa de reforço às estruturas de
betão armado. No que diz respeito ao sistema estrutural de lajes fungiformes, os avanços conseguidos
no campo da ciência dos materiais e das técnicas de construção já permitem a construção de estruturas
onde as lajes são reforçadas praticamente apenas por fibras de aço. Para que este novo sistema
construtivo possa competir com os métodos convencionais é necessário que os modelos teóricos que
descrevem o complexo comportamento da ligação laje-pilar acompanhem a evolução destas técnicas
construtivas. No entanto, ainda não existem regras de projeto que considerem a contribuição das fibras
de aço na resistência ao punçoamento de lajes fungiformes.
Com o intuito de contribuir para o aumento do conhecimento sobre o dimensionamento ao
punçoamento centrado de lajes fungiformes de betão reforçado com fibras de aço (BRFA), o presente
artigo apresenta e avalia o desempenho de quatro formulações semi-empíricas. Esse desempenho foi
avaliado comparando-se os resultados previstos por cada modelo, Vteo, com as respostas experimentais,
Vexp, de 154 lajes que compõem a base de dados (BD) construída para este efeito. As lajes da BD, além
de terem rompido todas por punçoamento, também cobrem uma ampla faixa de resistência à
compressão do betão, f
c
, de taxa de armadura de flexão, ρ, de altura útil das lajes, d, de percentagem
volumétrica de fibras, Vf
, e de esbelteza das fibras, L/D, em que L e D são o comprimento e o diâmetro
da fibra. Além da avaliação da relação Vexp/Vteo, também foi avaliada a influência que os parâmetros f
c
,
ρ, Vf
e L/D exercem sobre a capacidade preditiva dos modelos considerados
Primary Total Elbow Arthroplasty in the Treatment of Complex Elbow Fracture: A Case Report
Introduction: Some elbow fractures are very complex with
inadequate bone stock, so it is not possible to perform a stable
fixation. However, loss of basic elbow function can severely affect
daily living activities. There are few alternatives to internal fixation,
but arthroplasty can be a reasonable option. The aim of this case
report is to evaluate the role of primary total elbow arthroplasty in
the treatment of complex elbow fractures.
Case study: A 54-year-old male patient presented at our emergency
department in the sequence of a motorcycle accident, which caused
an open fracture of the left elbow, classified as type IIIB of Gustilo
and Anderson. The X-ray showed comminuted fractures of distal
humerus and proximal ulna with bone loss from both epiphysis.
He started antibiotherapy and was submitted to immediate surgical
debridement, provisional fixation with an external fixator and skin
closure. The external fixator was removed 2 months after, when
the patient presented with great elbow instability. The X-ray and
the Computed Tomography showed signals of malunion and bone
loss, which prevented any kind of fixation. Therefore, 3 months
after, the patient was submitted to elbow joint replacement. A
posterior approach was used, in which the triceps was reflected
and was applied a linked arthroplasty - Coonrad-Morrey total elbow
arthroplasty. On the second week after surgery, passive motion
was started and by the fourth week, progressed to active motion.
Six months after, he presented without significant pain and with a
range of motion of 0° to 135º.
Conclusions: Although rarely used, total elbow arthroplasty may
be the choice in selected patients with elbow fractures with loss of
bone. As shown in this case, this treatment can lead to a satisfactory
functional recovery. Despite having some complications, more
recent studies encourage its use in the future
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