2,980 research outputs found
Matching Conditions in Atomistic-Continuum Modeling of Materials
A new class of matching condition between the atomistic and continuum regions
is presented for the multi-scale modeling of crystals. They ensure the accurate
passage of large scale information between the atomistic and continuum regions
and at the same time minimize the reflection of phonons at the interface. These
matching conditions can be made adaptive if we choose appropriate weight
functions. Applications to dislocation dynamics and friction between
two-dimensional atomically flat crystal surfaces are described.Comment: 6 pages, 4 figure
Self Calibration of Tomographic Weak Lensing for the Physics of Baryons to Constrain Dark Energy
Numerical studies indicate that uncertainties in the treatment of baryonic
physics can affect predictions for shear power spectra at a level that is
significant for forthcoming surveys such as DES, SNAP, and LSST.
Correspondingly, we show that baryonic effects can significantly bias dark
energy parameter measurements. Eliminating such biases by neglecting
information in multipoles beyond several hundred leads to weaker parameter
constraints by a factor of approximately 2 to 3 compared with using information
out to multipoles of several thousand. Fortunately, the same numerical studies
that explore the influence of baryons indicate that they primarily affect power
spectra by altering halo structure through the relation between halo mass and
mean effective halo concentration. We explore the ability of future weak
lensing surveys to constrain both the internal structures of halos and the
properties of the dark energy simultaneously as a first step toward self
calibrating for the physics of baryons. This greatly reduces parameter biases
and no parameter constraint is degraded by more than 40% in the case of LSST or
30% in the cases of SNAP or DES. Modest prior knowledge of the halo
concentration relation greatly improves even these forecasts. Additionally, we
find that these surveys can constrain effective halo concentrations near
m~10^14 Msun/h and z~0.2 to better than 10% with shear power spectra alone.
These results suggest that inferring dark energy parameters with measurements
of shear power spectra can be made robust to baryonic effects and may
simultaneously be competitive with other methods to inform models of galaxy
formation. (Abridged)Comment: 18 pages, 11 figures. Minor changes reflecting referee's comments.
Results and conclusions unchanged. Accepted for publication in Physical
Review
High energy density aluminum-oxygen cell
An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell. An example of this is the metal-air fuel cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, having high energy and power densities, being environmentally acceptable, and having a large, established industrial base for production and distribution. An aluminum-oxygen system is currently under development for a UUV test vehicle, and recent work has focussed upon low corrosion aluminum alloys and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from S to 150 mA/sq cm have been identified. These materials are essential to realizing an acceptable mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 hours in a large scale, half-cell system
Recursive marginal quantization of higher-order schemes
© 2018 Informa UK Limited, trading as Taylor & Francis Group. Quantization techniques have been applied in many challenging finance applications, including pricing claims with path dependence and early exercise features, stochastic optimal control, filtering problems and efficient calibration of large derivative books. Recursive marginal quantization (RMQ) of the Euler scheme has recently been proposed as an efficient numerical method for evaluating functionals of solutions of stochastic differential equations. This method involves recursively quantizing the conditional marginals of the discrete-time Euler approximation of the underlying process. By generalizing this approach, we show that it is possible to perform RMQ for two higher-order schemes: the Milstein scheme and a simplified weak order 2.0 scheme. We further extend the applicability of RMQ by showing how absorption and reflection at the zero boundary may be incorporated, when necessary. To illustrate the improved accuracy of the higher-order schemes, various computations are performed using geometric Brownian motion and the constant elasticity of variance model. For both models, we provide evidence of improved weak order convergence and computational efficiency. By pricing European, Bermudan and barrier options, further evidence of improved accuracy of the higher-order schemes is demonstrated
Battered Women\u27s Compliance-Gaining Strategies as a Function of Argumentativeness and Verbal Aggression
This study investigated (1) the type of compliance-gaining strategies that battered women reported using in domestic conflicts and (2) whether these strategies related to the battered women\u27s verbal aggression and argumentativeness. Participants in this study were 115 abused women who were seeking refuge from abusive spouses in temporary shelters for battered women. The results suggest that battered women most frequently reported using indirect strategies. Aversive Stimulation (i.e., pouting sulking, crying) and ingratiation (i.e., manipulation in the form of affection or favor-doing) were the top two strategies reported. Furthermore, a canonical correlation analysis resulted in an overall significant relationship between compliance-gaining strategies and argumentativeness and verbal aggressiveness
A Twins Study of Communicative Adaptability: Heritability of Individual Differences
Recently, a model of communication theory and research has appeared in the literature within which stable individual differences in communication behavior represent individual differences in activation thresholds of neurobiological systems. The neurobiological systems thought to underly communication traits and behavior are assumed to be primarily due to genetic inheritance. As such, the model assigns a limited role to adaptability in social situations, instead positing communication adaptability as an inherited trait. In the present study, heritability estimates for the dimensions of communicative adaptability were derived from correlations based on identical and fraternal twins\u27 responses to a multidimensional communicative adaptability measure. Results indicated that social composure was 88% heritable, wit was 90% heritable, social confirmation was 37% heritable, articulation ability, and appropriate disclosure were 0% heritable. Theoretical implications are discussed
Viking navigation
A comprehensive description of the navigation of the Viking spacecraft throughout their flight from Earth launch to Mars landing is given. The flight path design, actual inflight control, and postflight reconstruction are discussed in detail. The preflight analyses upon which the operational strategies and performance predictions were based are discussed. The inflight results are then discussed and compared with the preflight predictions and, finally, the results of any postflight analyses are presented
Analytic binary alloy volume-concentration relations and the deviation from Zen`s law
Alloys expand or contract as concentrations change, and the resulting
relationship between atomic volume and alloy content is an important property
of the solid. While a well-known approximation posits that the atomic volume
varies linearly with concentration (Zen`s law), the actual variation is more
complicated. Here we use an apparent size of the solute (solvent) atom and the
elasticity to derive explicit analytical expressions for the atomic volume of
binary solid alloys. Two approximations, continuum and terminal, are proposed.
Deviations from Zen`s law are studied for 22 binary alloy systems
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