A new approach to the assessment of odour nuisance

After reviewing the current situation with regard to the assessment of odour nuisance, the development of a new approach is presented. Descriptions are given of the new techniques, which have been developed for quantifying odour intensity, concentration, hedonic tone and annoyance. Statistical analyses of laboratory and field test data collected using these techniques provided mathematical relationships 1 for the assembly of the odour nuisance assessment model. .The nuisance criteria adopted was derived from various guidelines and standards from the U.S. and Europe. For completeness an atmospheric dispersion model was developed for estimating the behaviour of odours downwind of the source. This made it possible to assess the probability of an odour nuisance occurring, using any one of a number of different points of knowledge, e.g. existing or future situations. The assessment method has been tested against independent historical data and been demonstrated to be an effective tool in predicting odour nuisance with a consistency better than any existing method. A listing is provided for a computer program to enable the user to apply the model both quickly and effectively

Surface Characterization of Laser Polished Indirect-SLS Parts

Surface analysis was performed on laser polished indirect-SLS samples made from 420 stainless steel sintered powder - bronze infiltrated. The goal was to determine variations from the as-received condition in surface chemical composition, morphological structure, presence of contaminants as well as the formation of new phases. Comprehensive characterization of the laser polished surfaces was performed using scanning electron microscopy (SEM), energy dispersive spectrochemical analysis (EDS), x-ray diffraction analysis (XRD) and Vickers hardness. A large quantity of carbon (i.e. > 29 wt%) was present on the as-received surface mostly from the polymer binder present in the green part. Although surface-shallow-melting is the principal mechanism for the roughness reduction of the as-received surface, the chemical composition of the latter after processing changed to a higher carbon and oxygen content and a lower copper content. Additionally, clusters were formed periodically over the polished surface consisting of Fe, Cr, Si and Al oxides. The surface analysis demonstrated that the laser polished surfaces differ significantly more from a morphological rather than a microstructural perspective.Mechanical Engineerin

Single-Layer Deposits of Nickel Base Superalloy by Means of Selective Laser Sintering

Single layer deposits consisting of Mar-M 247 powder were consolidated on Alloy 718 polycrystalline flat sheets by means of the Selective Laser Melting (SLM) technique. The deposition process consisted in selectively fusing a powder bed precompacted using of an insulating non-wettable mask trough. The mask-powder-substrate arrangement was pre-heated inside a processing chamber under high vacuum. An inertreducing atmosphere was applied, and a focused Nd:YAG laser beam was then raster scanned at high speed along the contour of the trough, providing energy to induce a melting front to propagate along the powder as well as over the surface of the plate. As the laser beam moved forward a solidification front was left behind with a metallurgical bond between the substrate and the deposited layer. Optical microscopy revealed that epitaxial growth occurred in the [001] direction from the melted substrate to about half the height of the deposits. Above that height, the [001] dendritic front bowed towards the [100] direction. A dendritic-equiaxed transition appeared near the free surface of the deposit. These results indicate that the SLM technique could have potential application for growing single crystal structures as well as in repairing damaged or worn turbine blades.Funding for this project was provided by Rolls-Royce North America and the University of Texas at Austin.Mechanical Engineerin

Nanosat Intelligent Power System Development

NASA Goddard Space Flight Center is developing a class of satellites called nano-satellites. The technologies developed for these satellites will enable a class of constellation missions for the NASA Space Science Sun-Earth Connections theme and will be of great benefit to other NASA enterprises. A major challenge for these missions is meeting significant scientific- objectives with limited onboard and ground-based resources. Total spacecraft power is limited by the small satellite size. Additionally, it is highly desirable to minimize operational costs by limiting the ground support required to manage the constellation. This paper will describe how these challenges are met in the design of the nanosat power system. We will address the factors considered and tradeoffs made in deriving the nanosat power system architecture. We will discuss how incorporating onboard fault detection and correction capability yields a robust spacecraft power bus without the mass and volume penalties incurred from redundant systems and describe how power system efficiency is maximized throughout the mission duration

Users’ experiences of lighting controls: a case-study

The aim of this paper is to elucidate how occupants perceive their lit environments in a university setting and how they interact with lighting controls using qualitative methods. Semi-structured interviews were carried out with academic teaching and research staff. Thematic analysis identified four main themes: control and choice, connection with the outdoors, concentration, and comfort. Participants were largely able to control and adapt their lighting using small power lighting in office spaces and they perceived this as beneficial to comfort and concentration. Participants expressed frustration with the light switches in classrooms, a lack of consistency in lighting controls across the university buildings was particularly notable. Installers should consider how piecemeal upgrades on large estates affect the perception of buildings where occupiers face multiple control systems. The management of the lighting in classroom spaces including the type and location of blinds, lack of regular window cleaning in some buildings and difficulty in minimising light on projection screens in upgraded classrooms were cited as areas for improvement. Wider implications for lighting control and management highlighted by this study include most notably that a lack of end users consultation has serious consequences on their perception of lighting upgrades and their willingness to employ “workarounds”

GeoOrigins: A new method and R package for trait mapping and geographic provenancing of specimens without categorical constraints

Biologists often seek to geographically provenance organisms using their traits. This is typically achieved by defining spatial groups using distinct patterns of trait variation. Here, we present a new spatial provenancing and trait boundary identification methodology, based on correlations between geographic and trait distances that require no a priori group assumptions. We apply this to three datasets where spatial provenance is sought: morphological rat and vole dentition data (human commensal translocation datasets); and birdsong data (cultural transmission dataset). We also present the results of cross‐validation testing. Spatial provenancing is possible with differing degrees of accuracy for each dataset, with birdsong providing the most accurate geographic origin (identifying an average spatial region of 0.22 km2 as the area of origin with 99.9% confidence). Our method has a wide range of potential applications to diverse data types—including phenotypic, genetic and cultural—to identify trait boundaries and spatially provenance the origin of unknown or translocated specimens where trait differences are geographically structured and correlated with spatial separation

Measuring linguistic complexity in long-term L2 speakers of English and L1 attriters of German

Linguistic complexity is neither easily defined nor measured. The challenge in finding reliable ways to measure linguistic complexity is even more pronounced when the variation of contexts in which complexity is measured is taken into account. This paper therefore aims at finding measures for assessing syntactic and lexical complexity that are sensitive and non-overlapping even in a less frequently studied context: spontaneous speech of L1 attriters and highly proficient L2 English speakers. To evaluate operationalizations of syntactic and lexical complexity, several previously proposed measures are applied to a corpus of spontaneous speech and a principal component analysis is conducted. The results show which of the measures group together as underlying variables of syntactic and lexical complexity and how this can inform future operationalizations of complexity

Low threshold particle arrays

While atmospheric Cherenkov telescopes have a small field of view and a small duty fraction, arrays of particle detectors on ground have a 1\,sr field of view and a 100% duty fraction. On the other hand, particle detector arrays have a much higher energy threshold and an inferior hadron rejection as compared to Cherenkov telescopes. Low threshold particle detector arrays would have potential advantages over Cherenkov telescopes in the search for episodic or unexpected sources of gamma rays in the multi-TeV energy range. Ways to improve the threshold and hadron rejection of arrays are shown, based on existing technology for the timing method (with scintillator or water Cherenkov counters) and the tracking method (with tracking detectors). The performance that could be achieved is shown by examples for both methods. At mountain altitude (about 4000 m or above) an energy threshold close to 1\,TeV could be achieved. For any significant reduction of the hadronic background by selecting muon-poor showers a muon detection area of at least 1000 m^2 is required, even for a compact array