28,787 research outputs found
Effects of carbon fibers on consumer products
The potential effects of carbon fibers on consumer products such as dishwashers, microwave ovens, and smoke detectors were investigated. The investigation was divided into two categories to determine the potential faults and hazards that could occur if fibers should enter the electrical circuits of the selected appliances. The categories were a fault analysis and a hazard analysis. Hazards considered were fire, flood, physical harm, explosion, and electrical shock. Electrical shock was found to be a possible occurrence related to carbon fibers. Faults were considered to be any effect on the performance of an appliance which would result in complaint or require service action
Exchange coupling between silicon donors: the crucial role of the central cell and mass anisotropy
Donors in silicon are now demonstrated as one of the leading candidates for
implementing qubits and quantum information processing. Single qubit
operations, measurements and long coherence times are firmly established, but
progress on controlling two qubit interactions has been slower. One reason for
this is that the inter donor exchange coupling has been predicted to oscillate
with separation, making it hard to estimate in device designs. We present a
multivalley effective mass theory of a donor pair in silicon, including both a
central cell potential and the effective mass anisotropy intrinsic in the Si
conduction band. We are able to accurately describe the single donor properties
of valley-orbit coupling and the spatial extent of donor wave functions,
highlighting the importance of fitting measured values of hyperfine coupling
and the orbital energy of the levels. Ours is a simple framework that can
be applied flexibly to a range of experimental scenarios, but it is nonetheless
able to provide fast and reliable predictions. We use it to estimate the
exchange coupling between two donor electrons and we find a smoothing of its
expected oscillations, and predict a monotonic dependence on separation if two
donors are spaced precisely along the [100] direction.Comment: Published version. Corrected b and B values from previous versio
Cyclization of W-tertiary Butyl Uramido Benzoic Acid
This 13 page thesis investigates the cyclization of w-tertiary butyl uramido benaoic acid and establishes the equation for the resulting reaction
Global nonlinear optimization of spacecraft protective structures design
The global optimization of protective structural designs for spacecraft subject to hypervelocity meteoroid and space debris impacts is presented. This nonlinear problem is first formulated for weight minimization of the space station core module configuration using the Nysmith impact predictor. Next, the equivalence and uniqueness of local and global optima is shown using properties of convexity. This analysis results in a new feasibility condition for this problem. The solution existence is then shown, followed by a comparison of optimization techniques. Finally, a sensitivity analysis is presented to determine the effects of variations in the systemic parameters on optimal design. The results show that global optimization of this problem is unique and may be achieved by a number of methods, provided the feasibility condition is satisfied. Furthermore, module structural design thicknesses and weight increase with increasing projectile velocity and diameter and decrease with increasing separation between bumper and wall for the Nysmith predictor
Surface code architecture for donors and dots in silicon with imprecise and nonuniform qubit couplings
A scaled quantum computer with donor spins in silicon would benefit from a
viable semiconductor framework and a strong inherent decoupling of the qubits
from the noisy environment. Coupling neighbouring spins via the natural
exchange interaction according to current designs requires gate control
structures with extremely small length scales. We present a silicon
architecture where bismuth donors with long coherence times are coupled to
electrons that can shuttle between adjacent quantum dots, thus relaxing the
pitch requirements and allowing space between donors for classical control
devices. An adiabatic SWAP operation within each donor/dot pair solves the
scalability issues intrinsic to exchange-based two-qubit gates, as it does not
rely on sub-nanometer precision in donor placement and is robust against noise
in the control fields. We use this SWAP together with well established global
microwave Rabi pulses and parallel electron shuttling to construct a surface
code that needs minimal, feasible local control.Comment: Published version - more detailed discussions, robustness to
dephasing pointed out additionall
Rapid and robust spin state amplification
Electron and nuclear spins have been employed in many of the early
demonstrations of quantum technology (QT). However applications in real world
QT are limited by the difficulty of measuring single spins. Here we show that
it is possible to rapidly and robustly amplify a spin state using a lattice of
ancillary spins. The model we employ corresponds to an extremely simple
experimental system: a homogenous Ising-coupled spin lattice in one, two or
three dimensions, driven by a continuous microwave field. We establish that the
process can operate at finite temperature (imperfect initial polarisation) and
under the effects of various forms of decoherence.Comment: 5 pages, 2 figure
Solving the brachistochrone and other variational problems with soap films
We show a method to solve the problem of the brachistochrone as well as other
variational problems with the help of the soap films that are formed between
two suitable surfaces. We also show the interesting connection between some
variational problems of dynamics, statics, optics, and elasticity.Comment: 16 pages, 11 figures. This article, except for a small correction,
has been submitted to the American Journal of Physic
EC82-1738 Tree Planting Guide
Site Preparation
Proper site preparation is essential to your tree planting operation, and varies with the different climates and soil types.
Chemical Control: On sandy soils, rough terrain, or other highly erodible sites, tillage is not recommended. Chemical weed and/or grass killers may be applied to the site in the fall or before planting in the spring.
Summer Fallow: This practice is recommended on heavy soil in western Nebraska to conserve soil moisture. This may be accomplished with the aid of occasional disking, subsurface tillage, or chemicals to control weeds.
Fall Tillage: In the eastern areas of the state fall plowing is recommended for grassland sites. Cropland may need no fall tillage. All sites should then be disked before spring planting
Electoral turnover has very little effect on the spending habits of Western democracies
Do new electoral brooms sweep clean the economic policies of the parties that went before? In new research that examines how incoming Western governments set their spending priorities, Derek A. Epp, John Lovett, and Frank R. Baumgartner find that budgets tend to be set with little regard to a government’s ideology, be it left or right. They argue that when setting budgets, incoming policymakers are constrained by social, economic and international realities that are largely beyond their control. This means that budgets are set consistently and inconsistently with what went before at roughly the same rate; left-wing parties do not necessarily favor “big government” nor to right parties always seek to reduce government spending
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