20,209 research outputs found
A Green Solution to Climate Change: The Hybrid Approach to Crediting Reductions in Tropical Deforestation
A simple model of quantum trajectories
Quantum trajectory theory, developed largely in the quantum optics community
to describe open quantum systems subjected to continuous monitoring, has
applications in many areas of quantum physics. In this paper I present a simple
model, using two-level quantum systems (q-bits), to illustrate the essential
physics of quantum trajectories and how different monitoring schemes correspond
to different ``unravelings'' of a mixed state master equation. I also comment
briefly on the relationship of the theory to the Consistent Histories formalism
and to spontaneous collapse models.Comment: 42 pages RevTeX including four figures in encapsulated postscript.
Submitted to special issue of American Journal of Physic
Computer program for off-design performance of radial inflow turbines
Computer program estimates off-design performance without making actual tests and design point performance. Turbine flow areas, diameters, and blade angles are required input information
Continuous monitoring can improve indistinguishability of a single-photon source
A new engineering technique using continuous quantum measurement in
conjunction with feed-forward is proposed to improve indistinguishability of a
single-photon source. The technique involves continuous monitoring of the state
of the emitter, processing the noisy output signal with a simple linear
estimation algorithm, and feed forward to control a variable delay at the
output. In the weak coupling regime, the information gained by monitoring the
state of the emitter is used to reduce the time uncertainty inherent in photon
emission from the source, which improves the indistinguishability of the
emitted photons.Comment: 4 pages, 4 figure
JT9D jet engine performance deterioration
The analytical techniques utilized to examine the effects of flight loads and engine operating conditions on performance deterioration are presented. The role of gyroscopic, gravitational, and aerodynamic loads are shown along with the effect of variations in engine build clearances. These analytical results are compared to engine test data along with the correlation between analytically predicted and measured clearances and rub patterns. Conclusions are drawn and important issues are discussed
Completely bounded kernels
We introduce completely bounded kernels taking values in L(A,B) where A and B
are C*-algebras. We show that if B is injective such kernels have a Kolmogorov
decomposition precisely when they can be scaled to be completely contractive,
and that this is automatic when the index set is countable.Comment: 22 pages. Fixed oversight in previous version. To appear in Acta
Scientiarum Mathematicarum (Szeged) for the 100th anniversary of the birth of
Bela Sz.-Nag
Validating Predictions of Unobserved Quantities
The ultimate purpose of most computational models is to make predictions,
commonly in support of some decision-making process (e.g., for design or
operation of some system). The quantities that need to be predicted (the
quantities of interest or QoIs) are generally not experimentally observable
before the prediction, since otherwise no prediction would be needed. Assessing
the validity of such extrapolative predictions, which is critical to informed
decision-making, is challenging. In classical approaches to validation, model
outputs for observed quantities are compared to observations to determine if
they are consistent. By itself, this consistency only ensures that the model
can predict the observed quantities under the conditions of the observations.
This limitation dramatically reduces the utility of the validation effort for
decision making because it implies nothing about predictions of unobserved QoIs
or for scenarios outside of the range of observations. However, there is no
agreement in the scientific community today regarding best practices for
validation of extrapolative predictions made using computational models. The
purpose of this paper is to propose and explore a validation and predictive
assessment process that supports extrapolative predictions for models with
known sources of error. The process includes stochastic modeling, calibration,
validation, and predictive assessment phases where representations of known
sources of uncertainty and error are built, informed, and tested. The proposed
methodology is applied to an illustrative extrapolation problem involving a
misspecified nonlinear oscillator
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