A high order finite element for completely incompressible creeping flow

A finite element method for simulating the creeping flow of an incompressible material is presented. The method allows for (1) a quadratic approximation of the velocity field, (2) material incompressibility everywhere within an element and (3) the ability to follow the flow through large changes of the material boundaries. A candle slowly bending under its own weight is simulated for illustrative purposes.     

Long wavelength GRIN-SCH MQW lasers incorporating graded GaAlInAs confinement layers

We report the growth and characterisation of the first GaAllnAs based GRIN-SCH MQW lasers operating at 1.3 and 1.6μm. In these devices, GaAllnAs barriers and either GalnAs or GaAllnAs wells have been used for the 1.6 and 1.3μm lasers, respectively, together with true continuously graded composition GaAlInAs regions for the confinement layers. The excellent structural quality of the active and confinement regions and control of wavelength uniformity has been confirmed. Buried ridge lasers fabricated from the GRIN-SCH MQW wafers lased at 1.3 and 1.6μm with CW threshold currents of 65 and 30 mA, respectively.     

Nuclear susceptibility of liquid He3—I

An accurate study of the nuclear molar susceptibility of liquid He ³ has been made. Particularly emphasized was the comparison of in the liquid with that in solid He ³ . The experimental results of this work define a three-dimensional surface T/C versus temperatureT and molar volumeV between 0.35 and 2.2° K and between 26 and 37 cm ³ /mole. HereC is the molar Curie constant of solid He ³ , assumed to beN _A µ ² /k _B T, where is the nuclear magnetic moment and N _A Avogadro's number. The measurements were accomplished using a carefully designed pulsed NMR set, and sample-and-hold circuitry with a digital voltmeter for readout. Most of the measurements were made at fixed temperature relative to a sample of bcc solid He ³ , usually at a density of 22.50 cm ³ /mole. These data were complemented by measurement of versusT at fixed pressure. Except at the highest temperatures, the scatter in the values was about 0.3%, and the results are estimated to be accurate within ±0.5%. At sufficiently high temperatures, the susceptibility is found to tend asymptotically towards Curie's law by comparison with solid He ³ . The deviation from Curie's law, to temperatures near 0.5° K, could be empirically written as (1–T/C)=bT ^d whereb andd are density-dependent parameters. Comparison with theories and previous measurements of the nuclear susceptibility are made. Below 1° K, the present results are about midway between those of Beal and Hatton ⁹ and those of Thomson, Meyer, and Adams. ⁸ Research supported by a grant from the National Science Foundation and from the AROD. The results have been presented as an Abstract inBull. Am. Phys. Soc. 14, 601 (1969), submitted in partial fulfillment for the Ph.D. in physics by J. R. Thompson, May 1969.     

The use of coal liquefaction catalysts for coal/oil coprocessing and heavy oil upgrading

The catalytic hydrogenation of heavy oil and mixed coal-heavy oil (coprocessing) systems has been the focus of a recent study at the Federal Energy Technology Center (FETC). The intent of this effort was to extend the use of coal liquefaction technologies to heavy oil upgrading and coprocessing systems. Specifically, new dispersed molybdenum-based catalysts developed at FETC and a novel silica-doped hydrous titanium oxide (HTO : Si)-supported NiMo catalyst developed at Sandia National Laboratories (SNL) were tested in these systems. The results indicate the potential of coal liquefaction catalysts for use in coprocessing and heavy oil upgrading. High conversions of coal–oil mixtures were observed with dispersed catalyst loadings as low as 100 ppm Mo. Similar results were observed in heavy oil systems. Also, the novel NiMo/HTO : Si catalyst was at least as effective as commercially-available supported catalysts (e.g. Amocat 1C) for conversion of high boiling point material to distillable products and aromatics removal.     

Functionalization of ethylene-propylene-diene terpolymer via the alder ene reaction

An ethylene-propylene-diene rubber (EPDM), containing 5 wt% 5-ethylidene-2-norbornene, was functionalized with maleic anhydride through the Alder Ene reaction at temperatures above 200°C in a co-rotating twin screw extruder. Characterization of the maleated product included FT-IR, ¹H and ¹³C NMR, and GPC. The degree of functionalization was determined by infrared analysis and by the mechanical properties of an ionic network formed by neutralizing the maleated rubber with zinc oxide. Increased temperature and maleic anhydride reactant concentration were found to improve the extent of reaction. Several Lewis acid species (SnCl₂?2H₂O, RuCl_n?xH₂O and AlCl₃) were tested as catalysts, and they were found to have a small effect on the degree of functionalization. This effect improved with reduced acid concentration. Among the Lewis acids examined, AlCl₃ gave rise to the greatest improvement of succinyl anhydride incorporation into the rubber.     

"It Gets You Away From Everyday Life": Local Woodlands and Community Use—What Makes a Difference?

This paper explores who uses woodlands near their homes, why they visit, what benefits they believe they obtain and what makes the difference between them choosing to visit or not. In the research, supported by the Forestry Commission, a multi-method, user-led approach was used, based on focus groups, questionnaire surveys and on-site observation in relation to five different communities in the central belt of Scotland. The conclusions demonstrate the overriding importance of childhood woodland visits as predictors of adult patterns of use. Proximity of woodlands is important for regular woodland users and freedom from rubbish is the physical quality people care most about. The physical qualities that make a difference as to whether people visit woodlands or not include directional signs, good information boards, variety of trees and tidiness of appearance. Perceptions of woodlands differ according to age and sex but are predominantly positive across all groups sampled: most people feel at peace in a woodland.     

Do ‘green’ buildings have better indoor environments? New evidence

A post-occupancy evaluation (POE) of 12 green and 12 conventional office buildings across Canada and the northern United States was conducted. Occupants (N = 2545) completed an online questionnaire related to environmental satisfaction, job satisfaction and organizational commitment, health and well-being, environmental attitudes, and commuting. In each building on-site physical measurements at a sample of workstations (N= 974) were taken, including: thermal conditions, air quality, acoustics, lighting, workstation size, ceiling height, window access and shading, and surface finishes. Green buildings exhibited superior performance compared with similar conventional buildings. Better outcomes included: environmental satisfaction, satisfaction with thermal conditions, satisfaction with the view to the outside, aesthetic appearance, less disturbance from heating, ventilation and air-conditioning (HVAC) noise, workplace image, night-time sleep quality, mood, physical symptoms, and reduced number of airborne particulates. A variety of physical features led to improved occupant outcomes across all buildings, including: conditions associated with speech privacy, lower background noise levels, higher light levels, greater access to windows, conditions associated with thermal comfort, and fewer airborne particulates. Green building rating systems might benefit from further attention in several areas, including: credits related to acoustic performance, a greater focus on reducing airborne particulates, enhanced support for the interdisciplinary design process and development of POE protocols.

Il a été mené une évaluation après occupation (POE) de 12 immeubles de bureaux verts et 12 immeubles de bureaux classiques répartis à travers le Canada et le nord des Etats-Unis. Les occupants (N?=?2545) ont rempli un questionnaire en ligne portant sur la satisfaction environnementale, la satisfaction au travail et l'implication organisationnelle, la santé et le bien-être, les attitudes environnementales, et les trajets réguliers. Dans chaque immeuble, des mesures physiques in situ sur un échantillon de postes de travail (N?=?974) ont été effectuées, comprenant : les conditions thermiques, la qualité de l'air, l'acoustique, l'éclairage, la taille des postes de travail, la hauteur de plafond, l'accès aux fenêtres et leur occultation, et les finitions de surface. Les bâtiments verts ont affiché des performances supérieures par rapport aux bâtiments classiques similaires. De meilleurs résultats ont été obtenus concernant la satisfaction environnementale, la satisfaction à l'égard des conditions thermiques, la satisfaction à l'égard de la vue sur l'extérieur, l'aspect esthétique, la diminution des perturbations liées aux bruits provenant du chauffage, de la ventilation et de la climatisation (CVC), l'image du lieu de travail, la qualité du sommeil nocturne, l'humeur, les symptômes physiques, et la réduction du nombre de particules en suspension dans l'air. Différentes caractéristiques physiques ont conduit à une amélioration des résultats pour les occupants dans tous les immeubles, concernant notamment les conditions liées à la confidentialité des conversations, les niveaux inférieurs de bruit de fond, les niveaux de luminosité plus élevés, l'accès accru aux fenêtres, les conditions associées au confort thermique, et le nombre moindre de particules en suspension dans l'air. Les systèmes de notation des bâtiments verts pourraient bénéficier d'une plus grande attention apportée à plusieurs domaines, s'agissant en particulier des crédits relatifs aux performances acoustiques, d'un accent accru sur la réduction des particules en suspension dans l'air, d'un soutien renforcé en faveur du processus de conception interdisciplinaire et du développement de protocoles POE.

Mots clés: performances des bâtiments, bilan environnemental, bâtiments verts, environnement intérieur, Leadership in Energy and Environmental Design (LEED), satisfaction des occupants, évaluation après occupation