3,999 research outputs found
Investigation of forest canopy temperatures recorded by the thermal infrared multispectral scanner at H. J. Andrews Experimental Forest
Thermal Infrared Multispectral Scanner (TIMS) data were collected over the H. J. Andrews Experimental Forest in Western Oregon on July 29, 1983 at approximately 1:30 p.m., Pacific Standard Time. The relation of changes in canopy temperature to green leaf biomass levels in reforested clearcuts and old-growth forest was investigated. A digital data base was generated in order to isolate that portion of the thermal emission that could be attributed to surface properties other than the vegetation biomass component. The TIMS appears to be capable of detecting subtle differences in ERT as related to canopy closure and green lead biomass, however calibration techniques are needed to correct for emissivity and atmospheric effects
Global modes and nonlinear analysis of inverted-flag flapping
An inverted flag has its trailing edge clamped and exhibits dynamics distinct
from that of a conventional flag, whose leading edge is restrained. We perform
nonlinear simulations and a global stability analysis of the inverted-flag
system for a range of Reynolds numbers, flag masses and stiffnesses. Our global
stability analysis is based on a linearisation of the fully-coupled
fluid-structure system of equations. The calculated equilibria are steady-state
solutions of the fully-coupled nonlinear equations. By implementing this
approach, we (i) explore the mechanisms that initiate flapping, (ii) study the
role of vortex shedding and vortex-induced vibration (VIV) in large-amplitude
flapping, and (iii) characterise the chaotic flapping regime. For point (i), we
identify a deformed-equilibrium state and show through a global stability
analysis that the onset of flapping is due to a supercritical Hopf bifurcation.
For large-amplitude flapping, point (ii), we confirm the arguments of Sader et
al. (2016) that for a range of parameters this regime is a VIV. We also show
that there are other flow regimes for which large-amplitude flapping persists
and is not a VIV. Specifically, flapping can occur at low Reynolds numbers
(), albeit via a previously unexplored mechanism. Finally, with respect to
point (iii), chaotic flapping has been observed experimentally for Reynolds
numbers of , and here we show that chaos also persists at a moderate
Reynolds number of 200. We characterise this chaotic regime and calculate its
strange attractor, whose structure is controlled by the above-mentioned
deformed equilibria and is similar to a Lorenz attractor. These results are
contextualised with bifurcation diagrams that depict the different equilibria
and various flapping regimes
Relationship between forest clearing and biophysical factors in tropical environments: Implications for the design of a forest change monitoring approach
The relationship between forest clearing, biophysical factors (e.g, ecological zones, slope gradient, soils), and transportation network in Costa Rica was analyzed. The location of forested areas at four reference datas (1940, 1950, 1961, and 1977) as derived from aerial photography and LANDSAT MSS data was digitilized and entered into a geographically-referenced data base. Ecological zones as protrayed by the Holdridge Life Zone Ecology System, and the location of roads and railways were also digitized from maps of the entire country as input to the data base. Information on slope gradient and soils was digitized from maps of a 21,000 square kilometer area. The total area of forest cleared over four decades are related to biophysical factors was analyzed within the data base and deforestation rates and trends were tabulated. The relatiohship between forest clearing and ecological zone and the influence of topography, sils, and transportation network are presented and discussed
Combining absolute and relative information in studies on food quality
A common problem in food science concerns the assessment of the quality of food samples. Typically, a group of panellists is trained exhaustively on how to identify different quality indicators in order to provide absolute information, in the form of scores, for each given food sample. Unfortunately, this training is expensive and time-consuming. For this very reason, it is quite common to search for additional information provided by untrained panellists. However, untrained panellists usually provide relative information, in the form of rankings, for the food samples. In this paper, we discuss how both scores and rankings can be combined in order to improve the quality of the assessment
The identity of Muslim women in South Africa : married couples' perspectives.
The present study provides an understanding of how married, tertiary educated and employed
Muslim females negotiate their identities across contexts within a multicultural environment, such as
post-1994 contemporary Johannesburg. An additional facet of this study was to gain insight into
the construction of Muslim female identity by the husbands of the women in the study. The
commonly portrayed images of Muslim women are unflattering and ill-conceived and depict the
Muslim woman as one who is veiled, oppressed, secluded and submissive. In South Africa however,
Muslim women have been able to participate in secular education and employment opportunities
and practice their religion within a democratic dispensation that is responsive to issues of gender.
In order to obtain an understanding of the nuances that underpin Muslim female self-constructions
and constructions by their husbands, the study was approached from a social constructionist
epistemology. It is the assumption of the researcher that identities are thus in part created
discursively, and for the purpose of this study, the constructions of identity of the participants were
analysed using a discourse analysis methodology. Interviews were conducted with four Muslim
couples. Social facets such as gender, race, religion and globalisation were used as topics in order
to understand how participants constructed Muslim women’s identity. The Muslim women who
participated in the study appear to inhabit different subject positions in their daily lives. The study
highlighted that identity may not be fixed or stable, rather a function of relational or contextual
positions. Both the women and men in this study emphasised an Islamic identification while
distancing themselves from a cultural identification. The oppression of Muslim women was
relegated to the realm of culture. In prioritising an Islamic identity the participants have created a
space where they are able to construct an alternative identity for Muslim women that enables
them these women the freedom to access secular spaces or what may be viewed as the public
sphere of men
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