Showing papers by "University of New Brunswick published in 1969"

Rapid Estimation of Heat Accumulation from Maximum and Minimum Temperatures

Abstract: A method is presented for estimating heat accumulation by using daily maximum and minimum temperatures and assuming the sine curve as an approximation of the diurnal temperature curve. A table is given for estimating heat accumulation for a given day, and a computer program is described for accumulating heat units over a 1—year period. The technique permits the use of an upper as well as a lower threshold and has a precision in the order of ± 5%.

Mechanics of Second Order Faults and Tension Gashes

Abstract: The origin of en echelon second order shear fractures and tension gashes associated with first order, or primary, faults is examined analytically and experimentally. It is postulated that en echelon second order structures form under the influence of a stress mechanism similar to the one occurring in the direct shear test. The direct shear or modified direct shear state of stress could develop at certain points along a forming primary fault as a result of a local reduction in the normal stress acting on planes perpendicular to the displacement direction. It is argued that in most en echelon arrays the orientation of the individual fractures reflects the existence of a local state of stress, and cannot directly be correlated with the regional (primary) stress field. The zone in which they occur, however, may represent planes of high effective shear stress within the regional framework. The direct shear model (full relief of transverse normal stress) offers a stress mechanism which can explain the origin of not only en echelon tension gashes but also second order faults. For a given set of strength parameters, the type of en echelon fractures that will develop depends on the normal stress acting in the primary fault plane. In general, tension fractures form at low normal stress, shear fractures at intermediate values of normal stress, and at high normal stress a crush or shear zone is produced. If the state of stress is one of modified direct shear (only partial relief of transverse normal stress), the development of second order faults is favored.

The activity of commercial water gas shift catalysts

Abstract: Published kinetic data for commercial water gas shift catalysts are interpreted in terms of pore diffusional effects. The Arrhenius plots of apparent activity show the curvature typical of the transition from reaction to pore diffusion control and the apparent activities of different catalyst pellets vary quite widely. Effective diffusivity data are used to calculate intrinsic rate constants from the apparent activity data and it is found that the intrinsic activities of the catalysts considered are all similar. Furthermore the intrinsic activities, calculated in this way, give linear Arrhenius plots and activation energies which are in good agreement with values obtained experimentally using small catalyst particles (22–27 K. Cals). The effect of pressure on apparent catalyst activity is also discussed and it is shown that this effect may be accounted for satisfactorily by pore diffusional effects and it is not necessary to assume a change in the intrinsic rate equation at least at pressures below 20 atms. On interprete, en fonction des effets de diffusion par les pores, les resultats cinetiques qui ont paru relativement aux catalyseurs employes dans la fabrication commerciale du gas a l'eau. Les traces d'Arrhenius pour l'activite apparente montrent que la courbure typique du passage de la reaction au controle de la diffusion par les pores, et les activites apparentes de differents catalyseurs en pastilles varient beaucoup. On a utilise les resultats de la diffusivite effective pour calculer les constantes de vitesse intrinseque a partir des donnees de l'activite apparente et l'on a trouve que les activites intrinseques des catalyseurs employes etaient toutes semblables. En outre, les activites intrinseques calculees de cette maniere produisent des traces d'Arrhenius lineaires et des energies d'activation qui concordent bien avec les valeurs obtenues experimentalement en utilisant des petites particules de catalyseur (22–27 kilocalories). On discute egalement l'effet de la pression sur l'activite apparente des catalyseurs et l'on demontre qu'on peut l'expliquer d'une maniere satisfaisante par les effets de diffusion par les pores et qu'il n'est pas necessaire de supposer qu'il y a changement dans l'equation de vitesse intrinseque, au moins lorsque la pression est inferieur a 20 atmospheres.

Accuracy of compensation methods in photoelastic fringe-order measurements: Paper presents an investigation into the error incurred due to improper setting of the isoclinic angle in the Tardy and the Sénarmont compensation methods

Abstract: A complete photoelastic stress analysis depends, in the majority of cases, on the accuracy of the fractional-fringe-order measurements. The error involved due to an error in the measurement of the isoclinic angle has been studied. It was found that the Tardy method was more accurate than the Senarmont method, assuming negligible errors in the optical elements.

Jump-resonance criteria for systems containing double-valued and frequency-dependent nonlinearities

Abstract: A procedure is developed for evaluating the jump-resonance frequencies for feedback systems containing nonlinearities which have complex and frequency-dependent describing functions. The method permits the determination of the multimodal region on the input amplitude/frequency plane, as well as other information concerning the system behaviour at the jump-resonance point. It is therefore convenient for use in the design of multimodal systems. The procedure is illustrated by means of two examples.

Opisthosomal musculature of female araneus diadematus (araneae: argiopidae)

Abstract: The opisthosomal musculature of adult female Araneus diadematus Clerck was investigated by means of dissections. Forty-nine different muscles, each paired, were found in the opisthosoma proper. Of these muscles, 7 pairs move the opisthosoma about the pedicel, 13 pairs compress the opisthosoma, 19 pairs move the spinnerets and colulus with respect to the opisthosoma, 4 pairs dilate the anus, 3 pairs dilate the genital aperture, and 3 pairs open the book-lung spiracles.

Desafios do planejamento urbano no Brasil e seus marcos legais sob a ótica da agricultura urbana

Abstract: Diante de um futuro incerto de mudancas climaticas, preve-se um colapso em grandes cidades do mundo. O cenario e produto da inseguranca alimentar gerada pelo distanciamento da agricultura local das areas adjacentes ao espaco urbano, contexto ja identificado em algumas civilizacoes no passado. Sob a perspectiva, assume-se que acoes de planejamento urbano devem estar integradas a estrategias de producao de alimentos a incluir iniciativas em favor da agricultura urbana e periurbana, e de praticas da permacultura. A considerar tais premissas, o objetivo da pesquisa e demonstrar os desafios do planejamento urbano no Brasil quando analisado sob a otica da agricultura urbana. Entende-se a necessidade de assumir novos conceitos e modelos de composicao do espaco, associados A permacultura e sua pratica experimental, considerando a integracao dos contextos urbanos (zonas intraurbanas, periurbanas e rurais) que atualmente nao apresentam claras inter-relacoes. Para aproximar o estudo A realidade brasileira foram analisadas, conjuntamente, as politicas sociais do Ministerio do Desenvolvimento Social e os marcos legais das politicas urbanas, a incluir o Estatuto da Cidade (Lei 10.257/2001) e a Lei 6.766/1979. Os resultados apontam que ha uma lacuna quanto A s acoes e praticas de agricultura urbana no âmbito legal de uso e ocupacao do solo e, portanto, sugerem-se algumas diretrizes de aplicacao.

Interfacial effects for transient heat conduction in the non‐continuum regime

Abstract: Experimental results are given which show that for non-continuum conditions for heat conduction between a solid surface and a gas, there is a surface zone (of probably four or five mean free paths in thickness) where the “effective” thermal conductivity gradually changes from a value governed by gas — solid wall interactions to the normal continuum value in the bulk phase. In the temperature-jump range, the effect of this surface zone in steady-state situations can be adequately expressed by a temperature-jump distance, but this approach is inadequate for transient state situations. In the transient state, a theory is required which allows for the gradually changing effective thermal conductivity in the surface zone. On presente deg resultats experimentaux qui demontrent que, dans des conditions non-continues de conduction de la chaleur entre une surface solide et un gaz, il ya une section ou zone de la surface (dont l'epaisseur correspond probablement a 4 ou 5 fois la distance moyenne parcourue librement par les molecules gazeuses), ou la conductivite thermique active passe graduellement d'une valeur regie par les reactions entre la paroi solide et le gaz a une valeur normale dans la phase continue du volume (bulk). Dans le regime du “temperature-jump”, on peut exprimer l'effet de la dite zone dans un regime permanent d'une maniere adequate au moyen d'une distance de discontinuite de temperature, mais cette methode est inadequate dans un regime transitoire, ou une theorie s'avere necessaire pour expliquer la conductivite thermique active qui change graduellement dans la section de la surface.

Quasilinear analysis of a nonlinear a.c. channel

Abstract: The letter shows how the response to a sinusoidal and/or Gaussian input for an a.c. channel containing a modulator, nonlinearity and demodulator in cascade can be obtained. Results for the modified nonlinearity and the equivalent gain to the signal are tabulated for various situations.

Stability of nonlinear-feedback systems with hysteretic controllers

Abstract: The paper presents a simple method for deriving frequency-domain-stability criteria for nonlinear-feedback systems which have hysteretic controllers. It is shown that the problem can be resolved by using known results on the stability of multidimensional systems if the hysteresis characteristic is modelled properly. A possible approach to the modelling problem is discussed. This leads to a representation of the hysteresis function in the form f (x, sgn ẋ), where sgn ẋ stands for the signum function of the derivative of the input signal. Three different cases of hysteresis are considered in the paper. Numerical examples of each of these are presented, together with experimental data.

Estimates of the transient response of Lur'e-type systems

Abstract: The problem of estimating the extreme time constants associated with the transient response of a Lur'e-type nonlinear system is considered This problem has been discussed in the recent past by Vogt,1 who showed that bounds for these time constants can be obtained from a knowledge of the eigenvalues of the linear part of the system The object of the present study has been to improve upon this result, by including the effects of the nonlinear part The proposed method is believed to be quite simple and is illustrated with the help of numerical examples

Análise dos parâmetros de conforto ambiental: estudo de caso na unidade de pronto atendimento de Samambaia no Distrito Federal

Abstract: This study evaluates the conditions of environmental comfort in the Emergency Care Unit (UPA) located in the Federal District, in the light of a theoretical framework based heavily on the contributions of recent years. To investigate the hygrothermal, sound, light and visual space characteristics, we chose the UPA Samambaia, as the object of study. The investigation was taken from the qualitative design, exploratory, using bibliographic research, standards and resolutions in force for the implementation of health care facilities and visual and photographic observations and interview. After data analysis, comparing them with the requirements recommended by the literature on environmental comfort, it was found that the UPA does not have adequate and satisfactory condition in terms of infrastructure.

Gestão do conhecimento organizacional na administração pública federal

Abstract: A premissa central deste artigo ? parte de uma pesquisa de mestrado ? e a verificacao doentendimento sobre o conceito e pratica de gestao do conhecimento na administracao publicafederal, onde foram selecionados e entrevistados nove gestores de organizacoes publicasfederais em Brasilia. Os resultados mostraram que a gestao do conhecimento organizacional,de acordo com o ponto de vista dos gestores publicos entrevistados, nao e como conceito, umaideia nova, mas um processo incipiente, cujo escopo, inserido no campo da cognicao humana,apenas comeca a ser discutido com mais profundidade na esfera da administracao publicaneste limiar do seculo XXI. Verificou-se, quando da aplicacao das entrevistas, no ano de2003, que nessas organizacoes publicas existe um significativo investimento nas areastecnologica e estrategica em detrimento dos investimentos nas areas de capacitacao edesenvolvimento de recursos humanos, que se constituem, na literatura revisada, como aessencia da gestao do conhecimento.

Correlated one-center wavefunctions for two-electron molecules

Abstract: A one-center configuration-interaction wavefunction for two-electron systems, built from nonorthogonal exponential-type orbitals may be multiplied by the correlation factor 1+αr12 and subjected to a variational treatment. All integrals can be evaluated, and are given in closed form. Applications are made to the ground state and an excited 1σ+ state of HeH+. The uncorrelated wavefunctions are based on the work by Stuart and Matsen. Due to the correlation factor the ground state energy at R=1.4 a.u. improves by 2.3% for a one-term and by 0.49% for a twenty-term wavefunction. The optimized value of α decreases as the number of terms increases. The best energy obtained for the ground state is −2.97458 a.u. at R=1.4 a.u. with α=0.27. Energy improvements for different R and changes in the orbital exponents were also studied. For the excited state the energy lowering due to the correlation factor becomes insignificant as the number of terms increases.