A dimensionality reduction method to select the most representative daylight illuminance distributions

One challenge when evaluating daylight distribution is dealing with the large amount of temporal and spatial data, visualisations and variability in illuminances that are assessed in buildings. Using a dimensionality reduction method based on principal component analysis, we identified the most representative annual daylight distributions. We modelled a rectangular room containing an analysis grid of 3200 illuminance sensor points and simulated 3285 different temporal daylight conditions using an annual occupancy schedule ranging from 08:00 to 17:00 with one-hour sampling intervals in two locations: Singapore and Oakland, California. Our approach explained 98 % of the illuminance variability with three daylight distributions in Singapore, and 92 % using six in Oakland, California. Our dimensionality reduction strategy was also generalised using a complex building geometry showing the utility of the method. We think this approach can be used to provide a more efficient and reliable method to analyse daylight performance in building practice

Excessive Strand End Slip in Prestressed Piles

This paper presents the results of a research project that investigated excessive strand end slip observed recently in some prestressed piles. From measurements taken in the field, it is apparent that the problem o excessive initial strand slip is independent of pile shape and size. Strand end slip is evident in piles of different manufacturers in different states in the Southeast. Excessive strand end slip was found in both the top and bottom of the cross section of the piles, although the top portion of the cross section generally exhibited much higher initial slip. Several preventive measures can be adopted to reduce the excessive strand end slip. These preventive measures include: a) proper concrete mixture proportioning to reduce top bar effect; b) use of higher-strength concrete with the lowest possible slump and setting time; c) assessment of the condition of the strands prior to installation to insure excellent bond characteristics; d) gradual release of prestress, with an optimal release sequence; and e) use of adequate vibration to ensure consolidation. The strand end slip measured at five prestressing plants in the Southeast is considerably higher than the allowable end slip and is expected to affect the pile performance. If the strand slip theory is adopted, the strand development length increases substantially due to the excessive strand end slip. A top bar effect factor similar to the one used in reinforced concrete design is recommended. To maintain the excellent quality of precast and prestressed concrete products, manufacturers should adopt a dynamic quality control process that follows the rapid changes in the industry. More tests are necessary to ensure excellent quality, such as the Moustafa or an equivalent test, to assess the bond capabilities of the strands, end slip measurements, and direct measurement of the transfer length. Installation of piles should proceed in a manner to alleviate the top bar effects by placing piles alternately in their best and worst directions

Disability's Digital Frictions: Activism, Technology and Politics

This paper argues that disability activism and politics can be seen as paradigmatic for the wider debates on the philosophies, forms, and formats embedded in technologies. Firstly, the paper discusses disability activism movements that use digital technology to intervene into digital technology, especially in the social media area. In both cases, activists seek to use the platforms themselves to argue for, and obtain, greater accessibility, customisability, and configurability, of the platform for users with disabilities. Yet there is a clear clash between philosophies embedded within these social media platforms, and the aspirations and values of many of the activist strands of disability. Secondly, the paper explores the use of digital technologies by disability activism movements in relation to welfare and work reforms—notably the UK struggles in the 2010–2014 periods. Here disability activists have made extensive use of digital media technologies, and we discuss their innovations, and the lessons they offer

Temporal effects in glare response

Discomfort glare is considered to be an annoyance or distraction caused by sources of non-uniform or high luminance within the field of view of an observer. There are still significant gaps in our understanding of the conditions that characterise the magnitude and occurrence of discomfort glare, this being especially evident in the presence of large sources of luminance such as windows. The large degree of scatter that is observed when subjective evaluations of glare sensation are compared against calculated glare indices suggests that discomfort glare may be dependent on other variables beyond the physical and photometric parameters that are commonly embedded in glare formulae (e.g., source luminance, source size, background luminance, and position index). There are strong reasons to believe that some of these variables might be linked to the time of day when the observer is exposed to the glare source. In response, this thesis investigated the research hypothesis that subjective glare sensation is associated with temporal variability. This hypothesis was tested in two stages. The first stage was conducted within a laboratory setting, and sought to examine temporal effects under controlled artificial lighting conditions. The collection of temporal variables and personal factors – thereby examining the scatter in glare responses across the independent variable (time of day) and isolating potential confounding variables – enabled to identify factors that could influence the subjective evaluation of glare sensation along the day. Having established the presence of a temporal effect on glare response, the influences detected were further explored within a test room with direct access to daylight, whereby temporal variables and personal factors were measured in conjunction to glare sensation for them to be statistically masked from the analysis. The results confirmed the hypothesis of an increased tolerance to glare as the day progresses. This supported the conclusion that physical and photometric parameters alone are not sufficient for a robust prediction of discomfort glare

M–M Bond-Stretching Energy Landscapes for M_2(dimen)_(4)^(2+) (M = Rh, Ir; dimen = 1,8-Diisocyanomenthane) Complexes

Isomers of Ir_2(dimen)_(4)^(2+) (dimen = 1,8-diisocyanomenthane) exhibit different Ir–Ir bond distances in a 2:1 MTHF/EtCN solution (MTHF = 2-methyltetrahydrofuran). Variable-temperature absorption data suggest that the isomer with the shorter Ir–Ir distance is favored at room temperature [K = ~8; ΔH° = −0.8 kcal/mol; ΔS° = 1.44 cal mol^(–1) K^(–1)]. We report calculations that shed light on M_2(dimen)_(4)^(2+) (M = Rh, Ir) structural differences: (1) metal–metal interaction favors short distances; (2) ligand deformational-strain energy favors long distances; (3) out-of-plane (A_(2u)) distortion promotes twisting of the ligand backbone at short metal–metal separations. Calculated potential-energy surfaces reveal a double minimum for Ir_2(dimen)_(4)^(2+) (4.1 Å Ir–Ir with 0° twist angle and ~3.6 Å Ir–Ir with ±12° twist angle) but not for the rhodium analogue (4.5 Å Rh–Rh with no twisting). Because both the ligand strain and A_(2u) distortional energy are virtually identical for the two complexes, the strength of the metal–metal interaction is the determining factor. On the basis of the magnitude of this interaction, we obtain the following results: (1) a single-minimum (along the Ir–Ir coordinate), harmonic potential-energy surface for the triplet electronic excited state of Ir_2(dimen)_(4)^(2+) (R_(e,Ir–Ir) = 2.87 Å; F_(Ir–Ir) = 0.99 mdyn Å^(–1)); (2) a single-minimum, anharmonic surface for the ground state of Rh_2(dimen)_(4)^(2+) (R_(e,Rh–Rh) = 3.23 Å; F_(Rh–Rh) = 0.09 mdyn Å^(–1)); (3) a double-minimum (along the Ir–Ir coordinate) surface for the ground state of Ir_2(dimen)_(4)^(2+) (R_(e,Ir–Ir) = 3.23 Å; F_(Ir–Ir) = 0.16 mdyn Å^(–1))

Satisfaction with indoor environmental quality in BREEAM and non-BREEAM certified office buildings

This paper presents preliminary analysis of occupant satisfaction with indoor environmental quality in Building Research Establishment Environmental Assessment Method (BREEAM) and non-BREEAM certified offices in the UK. Results from cross-sectional questionnaires (N = 121) showed that BREEAM certification per se did not seem to substantively influence building and workspace satisfaction. Conversely, occupants of BREEAM offices tended to be less satisfied with air quality and visual privacy than users of non-BREEAM buildings. Lower satisfaction was also detected in BREEAM offices for occupants having spent over 24 months in their building, and for users working in open-plan spaces. To interpret these findings, a methodology for data analysis was adopted whereas responses to point-in-time surveys (N = 82) were paired with environmental measurements. Broadening the perspective for appraising occupants’ perceptions, these combined techniques led to conclude that certification schemes should balance criteria addressing energy performance with design solutions considerate of issues of privacy, proxemics and perceived control over the qualities of the indoor environment

Equilibrium Current and Orbital Magnetization in a Quantum Hall Fluid

We present a general theory for the equilibrium current distribution in an interacting two-dimensional electron gas subjected to a perpendicular magnetic field, and confined by a potential that varies slowly on the scale of the magnetic length. The distribution is found to consist of strips or channels of current, which alternate in direction, and which have universal integrated strength.Comment: 13 pages, Revtex, to appear in the proceedings of the "Workshop on Novel Physics in Low-Dimensional Electron Systems" held in Madra

Temporal effects in glare response

Discomfort glare is considered to be an annoyance or distraction caused by sources of non-uniform or high luminance within the field of view of an observer. There are still significant gaps in our understanding of the conditions that characterise the magnitude and occurrence of discomfort glare, this being especially evident in the presence of large sources of luminance such as windows. The large degree of scatter that is observed when subjective evaluations of glare sensation are compared against calculated glare indices suggests that discomfort glare may be dependent on other variables beyond the physical and photometric parameters that are commonly embedded in glare formulae (e.g., source luminance, source size, background luminance, and position index). There are strong reasons to believe that some of these variables might be linked to the time of day when the observer is exposed to the glare source. In response, this thesis investigated the research hypothesis that subjective glare sensation is associated with temporal variability. This hypothesis was tested in two stages. The first stage was conducted within a laboratory setting, and sought to examine temporal effects under controlled artificial lighting conditions. The collection of temporal variables and personal factors – thereby examining the scatter in glare responses across the independent variable (time of day) and isolating potential confounding variables – enabled to identify factors that could influence the subjective evaluation of glare sensation along the day. Having established the presence of a temporal effect on glare response, the influences detected were further explored within a test room with direct access to daylight, whereby temporal variables and personal factors were measured in conjunction to glare sensation for them to be statistically masked from the analysis. The results confirmed the hypothesis of an increased tolerance to glare as the day progresses. This supported the conclusion that physical and photometric parameters alone are not sufficient for a robust prediction of discomfort glare

Biochar for Forest Restoration in Western States

This factsheet introduces biochar, bio-oil, synthesis gas, pyrolysis, and torrified wood products to the reader. We describe biochar production methods and applications for forest restoration projects in the Intermountain West

An Affordable Software Defined Radio

This paper discusses the utilization of a relatively inexpensive wideband radio receiver in combination with a digital downconverter (DDC) based data recorder to capture and record real world radio signals. The resulting in-phase (I) and quadrature (Q) data files are then imported intoMATLAB for processing. This batch processing of real world radio signals allows for a tremendous amount of classroom flexibility in the discussion of software defined radio topics