31 research outputs found
Fabrication of lightweight Si/SiC LIDAR mirrors
A new, chemical vapor deposition (CVD) process was developed for fabricating lightweight, polycrystalline silicon/silicon-carbide (Si/SiC) mirrors. The process involves three CVD steps: (1) to produce the mirror faceplate; (2) to form the lightweight backstructure, which is deposited integral to the faceplate; and (3) to deposit a layer of optical-grade material, e.g., Si, onto the front surface of the faceplate. The mirror figure and finish are fabricated into the faceplate
Fabrication of lightweight ceramic mirrors by means of a chemical vapor deposition process
A process to fabricate lightweigth ceramic mirrors, and in particular, silicon/silicon carbide mirrors, involves three chemical vapor deposition steps: one to produce the mirror faceplate, the second to form the lightweight backstructure which is deposited integral to the faceplate, and the third and final step which results in the deposition of a layer of optical grade material, for example, silicon, onto the front surface of the faceplate. The mirror figure and finish are fabricated into this latter material
Method of fabricating lightweight honeycomb structures
A process is disclosed for fabricating lightweight honeycomb type structures out of material such as silicon carbide (SiC) and silicon (S). The lightweight structure consists of a core to define the shape and size of the structure. The core is coated with an appropriate deposit such as SiC or Si to give the lightweight structure strength and stiffness and for bonding the lightweight structure to another surface. The core is fabricated from extremely thin ribs of appropriately stiff and strong material such as graphite. First, a graphite core consisting of an outer hexagonal cell with six inner triangular cells is constructed from the graphite ribs. The graphite core may be placed on the back-up side of a SiC faceplate and then coated with SiC to produce a monolithic structure without the use of any bonding agent. Cores and methods for the fabrication thereof in which the six inner triangular cells are further divided into a plurality of cells are also disclosed
Postdeposition Process for Improving Optical Properties of Chemical-Vapor-Deposited Silicon
English language proficiency and learning among Australian international postgraduate accounting students
Among OECD countries, Australia has the highest percentage of international students studying in its higher education institutions. Many of these students are motivated to study in Australia in order to find employment and immigrate. However, poor English language proficiency is the major barrier to employment outcomes despite labour shortages in many occupations. The Master of Professional Accounting Program (MPA) is an example of a program developed to attract international students to help meet the deficit of practising accountants, yet its graduates are failing to find employment. This paper reports on a survey of MPA students to investigate the role of English language proficiency on perceived learning experiences and outcomes. Findings reveal a significant relationship between language ability and engagement in learning. The paper concludes that English language development among international students is lacking both inside and outside the classroom
Using CHEMTAX to evaluate seasonal and interannual dynamics of the phytoplankton community off the South-west coast of Portugal
CHEMTAX was used to assess the relative contribution of the main phytoplankton classes to the total concentration of Chlorophyll a (Chl a) from the waters off SW coast of Portugal. Sampling campaigns were carried out during all seasons from 2008 to 2012, at three stations located 2, 10 and 18 km from the coast. Samples were taken from the surface, mid-Secchi and Secchi depth, for the determination of Chl a and other phytoplanktonic pigments by HPLC. Supporting data were also obtained including dissolved inorganic nutrients, salinity, transparency, temperature and upwelling indices. The CHEMTAX results were also related to microscopy counts and also spectral analysis of absorption of other samples from the same sampling campaigns. The pigment results showed that diatoms dominated from early spring to summer, coinciding with upwelling conditions, while cryptophytes, prymnesiophytes and prasinophytes dominated in autumn and winter, coinciding with seasonal stratification. Although the contribution of cyanobacteria to total Chl a was generally low, there were occasional sampling campaigns where it was exceptionally high, but these appeared not to be related to upwelling. Dinoflagellates and chrysophytes were minority groups although the pigment marker peridinin that was used to distinguish dinoflagellates was not adequate for distinguishing all the members of this group. CHEMTAX was particularly useful for discriminating between the smaller (0–20 μm) classes of the microplankton that could not be easily identified by microscopy.This research was funded by European Space Agency as part of the project “Technical assistance for the validation of MERIS marine products at Portuguese oceanic and coastal sites” (contract n° 21464/08/I-OL). P.C. Goela and S. Cristina are funded by PhD grants from FCT (SFRH/BD/78356/2011 and SFRH/BD/78354/2011, respectively); S. Danchenko is funded by Erasmus Mundus EMJD MACOMA; A. Newton is funded by EU FP7 project DEVOTES (grant agreement no. 308392), www.devotes-project.eu. J. Icely is funded by EU FP7 AQUA_USER (grant agreement no. 607325) www.aqua-users.eu.Peer reviewe