1,841 research outputs found
Simulation of fluid flows during growth of organic crystals in microgravity
Several counter diffusion type crystal growth experiments were conducted in space. Improvements in crystal size and quality are attributed to reduced natural convection in the microgravity environment. One series of experiments called DMOS (Diffusive Mixing of Organic Solutions) was designed and conducted by researchers at the 3M Corporation and flown by NASA on the space shuttle. Since only limited information about the mixing process is available from the space experiments, a series of ground based experiments was conducted to further investigate the fluid dynamics within the DMOS crystal growth cell. Solutions with density differences in the range of 10 to the -7 to 10 to the -4 power g/cc were used to simulate microgravity conditions. The small density differences were obtained by mixing D2O and H2O. Methylene blue dye was used to enhance flow visualization. The extent of mixing was measured photometrically using the 662 nm absorbance peak of the dye. Results indicate that extensive mixing by natural convection can occur even under microgravity conditions. This is qualitatively consistent with results of a simple scaling analysis. Quantitave results are in close agreement with ongoing computational modeling analysis
Public Beach Assessment Report Aqua-PO Stafford county, Virginia
The Aqua-Po Public Beach report is the first in a series of reports on the public beaches in the Commonwealth of Virginia. There are 14 localities with public beaches totaling about 23 miles of shoreline. The public beach reports are an assessment of the history of each public beach and their current status in terms of loss of beach fill and maintenance needed. This is measured by the beach monitoring program sponsored by the Virginia Board on the Conservation and Development of Public Beaches
Flexible working, work–family conflict, and maternal gatekeeping: The daily experiences of dual-earner couples
This study explores the impact of flexible working on the daily experiences of work–family conflict for dual-earner couples with child dependants. In exploring these daily experiences, the occurrence of maternal gatekeeping behaviours, and the relationship between flexible working and such behaviours is investigated. We draw on episodic and longitudinal data from qualitative diaries kept for a 1-month period by both members of 24 couples (48 participants) as well as from introductory and subsequent in-depth qualitative interviews with the couples, both together and apart. We report an evidence suggesting that work–family conflicts are experienced and resolved differently, depending on whether it is the male or the female who works flexibly within dual-earner couples. This link between flexible working and gender is demonstrated to have an important impact on maternal gatekeeping behaviours, which are highlighted as playing a crucial role in such daily experiences and how they are resolved
Networked Assembly of Affine Physical System Models
Engineering design is evolving into a global strategy that distributes engineering effort to team members around the world. Because modern engineering design uses analytical models, model information mus
Developing a Pedagogical Framework for Designing a Multisensory Serious Gaming Environment
The importance of multisensory interaction for learning has increased with improved understanding of children’s sensory development, and a flourishing interest in embodied cognition. The potential to foster new forms of multisensory interaction through various sensor, mobile and haptic technologies is promising in providing new ways for young children to engage with key mathematical concepts. However, designing effective learning environments for real world classrooms is challenging, and requires a pedagogically, rather than technologically, driven approach to design. This paper describes initial work underpinning the development of a pedagogical framework, intended to inform the design of a multisensory serious gaming environment. It identifies the theoretical basis of the framework, illustrates how this informs teaching strategies, and outlines key technology research driven perspectives and considerations important for informing design. An initial table mapping mathematical concepts to design, a framework of considerations for design, and a process model of how the framework will continue to be developed across the design process are provided
Memetic Multilevel Hypergraph Partitioning
Hypergraph partitioning has a wide range of important applications such as
VLSI design or scientific computing. With focus on solution quality, we develop
the first multilevel memetic algorithm to tackle the problem. Key components of
our contribution are new effective multilevel recombination and mutation
operations that provide a large amount of diversity. We perform a wide range of
experiments on a benchmark set containing instances from application areas such
VLSI, SAT solving, social networks, and scientific computing. Compared to the
state-of-the-art hypergraph partitioning tools hMetis, PaToH, and KaHyPar, our
new algorithm computes the best result on almost all instances
Critical behavior of thermopower and conductivity at the metal-insulator transition in high-mobility Si-MOSFET's
This letter reports thermopower and conductivity measurements through the
metal-insulator transition for 2-dimensional electron gases in high mobility
Si-MOSFET's. At low temperatures both thermopower and conductivity show
critical behavior as a function of electron density which is very similar to
that expected for an Anderson transition. In particular, when approaching the
critical density from the metallic side the diffusion thermopower appears to
diverge and the conductivity vanishes. On the insulating side the thermopower
shows an upturn with decreasing temperature.Comment: 4 pages with 3 figure
Coherent states for a particle on a sphere
The coherent states for a particle on a sphere are introduced. These states
are labelled by points of the classical phase space, that is the position on
the sphere and the angular momentum of a particle. As with the coherent states
for a particle on a circle discussed in Kowalski K {\em et al} 1996 {\em J.
Phys. A} {\bf 29} 4149, we deal with a deformation of the classical phase space
related with quantum fluctuations. The expectation values of the position and
the angular momentum in the coherent states are regarded as the best possible
approximation of the classical phase space. The correctness of the introduced
coherent states is illustrated by an example of the rotator.Comment: LaTeX, 16 pages, 2 figure
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