2,614 research outputs found
Fabrication of an in-plane SU-8 cantilever with integrated strain gauge for wall shear stress measurements in fluid flows.
We present a cantilever fabricated from the polymer SU-8 for the measurement of wall shear stress in fluid flows. The pressure induced deflection of the cantilever, measured using a calibrated and integrated nichrome strain gauge, can be related to the wall shear stress on the surface. The initial degree of curvature of the cantilever can be controlled via the exposure dose, which allows a small positive deflection to be achieved, and so minimises the intrusion into the flow. Wind tunnel testing results show a sensitivity greater than 2.5 mV/Pa, with a shear stress of 0.38 Pa and excitation of 1 V
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U.S. solid oxide fuel cell powerplant development and commercialization
SOFC powerplants have many potential attributes which make them suitable for distributed generation applications. Power densities for SOFCs are very promising. Power densities possibilities of 20 watts per square centimeter have been reported to be possible. Westinghouse Electric is the leader in tubular SOFC technology. Several completely packaged and self-contained generators, up to nominal 25-kW size, have been manufactured and tested by Westinghouse Electric. A manufacturing facility currently produces these generators. In the US, several planar designs are also under development. Organizations developing planar designs include IGT, Celamalec, Ztek, TMI, and Allied Signal Aerospace. One of the most promising developments in SOFC powerplants is the conceptual development of very high efficiency fuel cell gas turbine powerplants. Combination of SOFC and turbine has the potential for enormous synergies
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Fuel cell market applications
This is a review of the US (and international) fuel cell development for the stationary power generation market. Besides DOE, GRI, and EPRI sponsorship, the US fuel cell program has over 40% cost-sharing from the private sector. Support is provided by user groups with over 75 utility and other end-user members. Objectives are to develop and demonstrate cost-effective fuel cell power generation which can initially be commercialized into various market applications using natural gas fuel by the year 2000. Types of fuel cells being developed include PAFC (phosphoric acid), MCFC (molten carbonate), and SOFC (solid oxide); status of each is reported. Potential international applications are reviewed also. Fuel cells are viewed as a force in dispersed power generation, distributed power, cogeneration, and deregulated industry. Specific fuel cell attributes are discussed: Fuel cells promise to be one of the most reliable power sources; they are now being used in critical uninterruptible power systems. They need hydrogen which can be generated internally from natural gas, coal gas, methanol landfill gas, or other fuels containing hydrocarbons. Finally, fuel cell development and market applications in Japan are reviewed briefly
Global Symposium on Women in Fisheries
All over the world, women contribute in multiple ways to the production, processing, marketing and management of fish and other living aquatic resources. The first ever Global Symposium on Women in Fisheries, held in Kaohsiung, Taiwan on 29 November 2001 generated the present collection of papers on women in fisheries. The reader of this volume will find in it a wealth of information, albeit in a very heterogeneous form, that the authors have had to draw from many different sources. Some are primary research studies whereas most are historical reviews from first hand experience of the authors or derived from other written materials, often contained in reports of fisheries development projects, newspapers and source materials well outside the fish sectors.Women, Participation, Sustainability, Poverty, Fisheries, Development projects, Fishery technology
H2 in the interstitial channels of nanotube bundles
The equation of state of H2 adsorbed in the interstitial channels of a carbon
nanotube bundle has been calculated using the diffusion Monte Carlo method. The
possibility of a lattice dilation, induced by H2 adsorption, has been analyzed
by modeling the cohesion energy of the bundle. The influence of factors like
the interatomic potentials, the nanotube radius and the geometry of the channel
on the bundle swelling is systematically analyzed. The most critical input is
proved to be the C-H2 potential. Using the same model than in planar graphite,
which is expected to be also accurate in nanotubes, the dilation is observed to
be smaller than in previous estimations or even inexistent. H2 is highly
unidimensional near the equilibrium density, the radial degree of freedom
appearing progressively at higher densities.Comment: Accepted for publication in PR
Exploiting topology-directed nanoparticle disassembly for triggered drug delivery
YesThe physical properties of cyclic and linear polymers are markedly different; however, there are few examples which exploit these differences in clinical applications. In this study, we demonstrate that self-assemblies comprised of cyclic-linear graft copolymers are significantly more stable than the equivalent linear-linear graft copolymer assemblies. This difference in stability can be exploited to allow for triggered disassembly by cleavage of just a single bond within the cyclic polymer backbone, via disulfide reduction, in the presence of intracellular levels of l-glutathione. This topological effect was exploited to demonstrate the first example of topology-controlled particle disassembly for the controlled release of an anti-cancer drug in vitro. This approach represents a markedly different strategy for controlled release from polymer nanoparticles and highlights for the first time that a change in polymer topology can be used as a trigger in the design of delivery vehicles. We propose such constructs, which demonstrate disassembly behavior upon a change in polymer topology, could find application in the targeted delivery of therapeutic agents.ERC are acknowledged for support to M.C.A., A.P.D. (grant number: 681559) and R.O.R. (grant number: 615142)
Theory of periodic swarming of bacteria: application to Proteus mirabilis
The periodic swarming of bacteria is one of the simplest examples for pattern
formation produced by the self-organized collective behavior of a large number
of organisms. In the spectacular colonies of Proteus mirabilis (the most common
species exhibiting this type of growth) a series of concentric rings are
developed as the bacteria multiply and swarm following a scenario periodically
repeating itself. We have developed a theoretical description for this process
in order to get a deeper insight into some of the typical processes governing
the phenomena in systems of many interacting living units. All of our
theoretical results are in excellent quantitative agreement with the complete
set of available observations.Comment: 11 pages, 8 figure
Rotating black hole orbit functionals in the frequency domain
In many astrophysical problems, it is important to understand the behavior of
functions that come from rotating (Kerr) black hole orbits. It can be
particularly useful to work with the frequency domain representation of those
functions, in order to bring out their harmonic dependence upon the fundamental
orbital frequencies of Kerr black holes. Although, as has recently been shown
by W. Schmidt, such a frequency domain representation must exist, the coupled
nature of a black hole orbit's and motions makes it difficult to
construct such a representation in practice. Combining Schmidt's description
with a clever choice of timelike coordinate suggested by Y. Mino, we have
developed a simple procedure that sidesteps this difficulty. One first Fourier
expands all quantities using Mino's time coordinate . In particular,
the observer's time is decomposed with . The frequency domain
description is then built from the -Fourier expansion and the
expansion of . We have found this procedure to be quite simple to implement,
and to be applicable to a wide class of functionals. We test the procedure
using a simple test function, and then apply it in a particularly interesting
case, the Weyl curvature scalar used in black hole perturbation
theory.Comment: 16 pages, 2 figures. Submitted to Phys Rev D. New version gives a
vastly improved algorithm due to Drasco for computing the Fourier transforms.
Drasco has been added as an author. Also fixed some references and
exterminated a small herd of typos; final published versio
Understorey plant community and light availability in conifer plantations and natural hardwood forests in Taiwan
Questions: What are the effects of replacing mixed species natural forests with Cryptomeria japonica plantations on understorey plant functional and species diversity? What is the role of the understorey light environment in determining understorey diversity and community in the two types of forest?
Location: Subtropical northeast Taiwan.
Methods: We examined light environments using hemispherical photography, and diversity and composition of understorey plants of a 35‐yr C. japonica plantation and an adjacent natural hardwood forest.
Results: Understorey plant species richness was similar in the two forests, but the communities were different; only 18 of the 91 recorded understorey plant species occurred in both forests. Relative abundance of plants among different functional groups differed between the two forests. Relative numbers of shade‐tolerant and shade‐intolerant seedling individuals were also different between the two forest types with only one shade‐intolerant seedling in the plantation compared to 23 seedlings belonging to two species in the natural forest. In the natural forest 11 species of tree seedling were found, while in the plantation only five were found, and the seedling density was only one third of that in the natural forest. Across plots in both forests, understorey plant richness and diversity were negatively correlated with direct sunlight but not indirect sunlight, possibly because direct light plays a more important role in understorey plant growth.
Conclusions: We report lower species and functional diversity and higher light availability in a natural hardwood forest than an adjacent 30‐yr C. japonica plantation, possibly due to the increased dominance of shade‐intolerant species associated with higher light availability. To maintain plant diversity, management efforts must be made to prevent localized losses of shade‐adapted understorey plants
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