Natural ventilation of multiple storey buildings: The use of stacks for secondary ventilation

The natural ventilation of buildings may be enhanced by the use of stacks. As well as increasing the buoyancy pressure available\ud to drive a flow, the stacks may also be used to drive ventilation in floors where there is little heat load. This is achieved by connecting\ud the floor with a relatively low heat load to a floor with a higher heat load through a common stack. The warm air expelled from the\ud warmer space into the stack thereby drives a flow through the floor with no heat load. This principle of ventilation has been adopted\ud in the basement archive library of the new SSEES building at UCL. In this paper a series of laboratory experiments and supporting\ud quantitative models are used to investigate such secondary ventilation of a low level floor driven by a heat source in a higher level\ud floor. The magnitude of the secondary ventilation within the lower floor is shown to increase with the ratio of the size of the\ud openings on the lower to the upper floor and also the height of the stack. The results also indicate that the secondary ventilation\ud leads to a reduction in the magnitude of the ventilation through the upper floor, especially if the lower floor has a large inlet area.\ud r 2005 Elsevier Ltd. All rights reserve

Faculty Perceptions Of Student Credibility Based On Email Addresses

The purpose of this study was to evaluate faculty perceptions of student credibility based on email addresses.  The survey was conducted at an upper division business school in Michigan where all students have completed at least two years of college courses.   The survey results show that a student’s selection of an email address does influence the faculty’s perception of their credibility.  An email address that consists of a nickname reduces the faculty’s perception of student credibility as well as the domain name of the email service used by the student   The reduced credibility  may have a negative impact on the faculty member’s perception of the student.

Student Perceptions Of Faculty Credibility Based On Email Addresses

The purpose of this study was to evaluate students’ perceptions of faculty credibility based on email addresses.  The survey was conducted at an upper division business school in Michigan where all students have completed at least two years of college courses.   The survey results show that a faculty member’s selection of an email address does influence the student’s perception of faculty credibility.  An email address that consists of a nickname reduces the student’s perception of faculty credibility.  The reduced creditability may have a negative impact on the faculty member as well as the college.&nbsp

HST followup observations of two bright z ~ 8 candidate galaxies from the BoRG pure-parallel survey

We present followup imaging of two bright (L > L*) galaxy candidates at z > 8 from the Brightest of Reionizing Galaxies (BoRG) survey with the F098M filter on HST/WFC3. The F098M filter provides an additional constraint on the flux blueward of the spectral break, and the observations are designed to discriminate between low- and high-z photometric redshift solutions for these galaxies. Our results confirm one galaxy, BoRG 0116+1425 747, as a highly probable z ~ 8 source, but reveal that BoRG 0116+1425 630 - previously the brightest known z > 8 candidate (mAB = 24.5) - is likely to be a z ~ 2 interloper. As this source was substantially brighter than any other z > 8 candidate, removing it from the sample has a significant impact on the derived UV luminosity function in this epoch. We show that while previous BoRG results favored a shallow power-law decline in the bright end of the luminosity function prior to reionization, there is now no evidence for departure from a Schechter function form and therefore no evidence for a difference in galaxy formation processes before and after reionization.Comment: Accepted by ApJL, 7 pages, 4 figure

Dephasing Effect in Photon-Assisted Resonant Tunneling through Quantum Dots

We analyze dephasing in single and double quantum dot systems. The decoherence is introduced by the B\"{u}ttiker model with current conserving fictitious voltage leads connected to the dots. By using the non-equilibrium Green function method, we investigate the dephasing effect on the tunneling current. It is shown that a finite dephasing rate leads to observable effects. The result can be used to measure dephasing rates in quantum dots.Comment: 4 pages, 3 figures, to be published in Rapid Communications of Phys. Rev.

Characterisation of columnar inertial modes in rapidly rotating spheres and spheroids

We consider fluid-filled spheres and spheroidal containers of eccentricity ε in rapid rotation, as a proxy for the interior dynamics of stars and planets. The fluid motion is assumed to be quasi-geostrophic (QG): horizontal motions are invariant parallel to the rotation axis z, a characteristic which is handled by use of a stream function formulation which additionally enforces mass conservation and non-penetration at the boundary. By linearising about a quiescent background state, we investigate a variety of methods to study the QG inviscid inertial wave modes which are compared with fully 3-D calculations. We consider the recently-proposed weak formulation of the inviscid system valid in spheroids of arbitrary eccentricity, to which we present novel closed-form polynomial solutions. Our modal solutions accurately represent, in both spatial structure and frequency, the most z-invariant of the inertial wave modes in a spheroid, and constitute a simple basis set for the analysis of rotationally dominated fluids. We further show that these new solutions are more accurate than those of the classical axial-vorticity equation, which is independent of ε and thus fails to properly encode the container geometry. We also consider the effects of viscosity for the cases of both no-slip and stress-free boundary conditions for a spherical container. Calculations performed under the columnar approximation are compared with 3-D solutions and excellent agreement has been found despite fundamental differences in the two formulations

Student Perceptions Of Peer Credibility Based On Email Addresses

The purpose of this study was to evaluate students’ perceptions of their peer’s credibility based on email addresses.  The survey was conducted at a community college in Michigan where all students were registered and actively taking at least one course.  The survey results show that a student’s selection of an email address does influence other students’ perception of their credibility.  An email address that consists of a nickname reduces the student’s perception of peer credibility

Full sphere hydrodynamic and dynamo benchmarks

Convection in planetary cores can generate fluid flow and magnetic fields, and a number of sophisticated codes exist to simulate the dynamic behaviour of such systems. We report on the first community activity to compare numerical results of computer codes designed to calculate fluid flow within a whole sphere. The flows are incompressible and rapidly rotating and the forcing of the flow is either due to thermal convection or due to moving boundaries. All problems defined have solutions that allow easy comparison, since they are either steady, slowly drifting or perfectly periodic. The first two benchmarks are defined based on uniform internal heating within the sphere under the Boussinesq approximation with boundary conditions that are uniform in temperature and stress-free for the flow. Benchmark 1 is purely hydrodynamic, and has a drifting solution. Benchmark 2 is a magnetohydrodynamic benchmark that can generate oscillatory, purely periodic, flows and magnetic fields. In contrast, Benchmark 3 is a hydrodynamic rotating bubble benchmark using no slip boundary conditions that has a stationary solution. Results from a variety of types of code are reported, including codes that are fully spectral (based on spherical harmonic expansions in angular coordinates and polynomial expansions in radius), mixed spectral and finite difference, finite volume, finite element and also a mixed Fourier–finite element code. There is good agreement between codes. It is found that in Benchmarks 1 and 2, the approximation of a whole sphere problem by a domain that is a spherical shell (a sphere possessing an inner core) does not represent an adequate approximation to the system, since the results differ from whole sphere results