3,298 research outputs found
Wind tunnel test results of a new leading edge flap design for highly swept wings, a vortex flap
A leading edge flap design for highly swept wings, called a vortex flap, was tested on an arrow wing model in a low speed wind tunnel. A vortex flap differs from a conventional plain flap in that it has a leading edge tab which is counterdeflected from the main portion of the flap. This results in intentional separation at the flap leading edge, causing a vortex to form and lie on the flap. By trapping this vortex, the vortex flap can result in significantly improved wing flow characteristics relative to conventional flaps at moderate to high angles of attack, as demonstrated by the flow visualization results of this tests
Planetary geometry handbook: Venus positional data, 1988 - 2020, volume 2
Graphical data necessary for the analysis of planetary exploration missions to Venus are presented. Positional and geometric information spanning the time period from 1988 through 2020 is provided. The data and the usage are explained
Planetary geometry handbook: Mars positional data, 1990 - 2020, volume 3
Graphical data necessary for the analysis of planetary exploration missions to Mars are presented. Positional and geometric information spanning the time period from 1990 through 2020 is provided. The data and usage are explained
Planetary geometry handbook: Saturn positional data, 1985 - 2020, volume 5
Graphical data necessary for the analysis of planetary exploration missions to Saturn are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained
Planetary geometry handbook: Jupiter positional data, 1985 - 2020, volume 4
Graphical data necessary for the analysis of planetary exploration missions to Jupiter are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained
A security proof of continuous-variable QKD using three coherent states
We introduce a ternary quantum key distribution (QKD) protocol and asymptotic
security proof based on three coherent states and homodyne detection. Previous
work had considered the binary case of two coherent states and here we
nontrivially extend this to three. Our motivation is to leverage the practical
benefits of both discrete and continuous (Gaussian) encoding schemes creating a
best-of-both-worlds approach; namely, the postprocessing of discrete encodings
and the hardware benefits of continuous ones. We present a thorough and
detailed security proof in the limit of infinite signal states which allows us
to lower bound the secret key rate. We calculate this is in the context of
collective eavesdropping attacks and reverse reconciliation postprocessing.
Finally, we compare the ternary coherent state protocol to other well-known QKD
schemes (and fundamental repeaterless limits) in terms of secret key rates and
loss.Comment: Close to the published versio
Machine-Checked Proofs For Realizability Checking Algorithms
Virtual integration techniques focus on building architectural models of
systems that can be analyzed early in the design cycle to try to lower cost,
reduce risk, and improve quality of complex embedded systems. Given appropriate
architectural descriptions, assume/guarantee contracts, and compositional
reasoning rules, these techniques can be used to prove important safety
properties about the architecture prior to system construction. For these
proofs to be meaningful, each leaf-level component contract must be realizable;
i.e., it is possible to construct a component such that for any input allowed
by the contract assumptions, there is some output value that the component can
produce that satisfies the contract guarantees. We have recently proposed (in
[1]) a contract-based realizability checking algorithm for assume/guarantee
contracts over infinite theories supported by SMT solvers such as linear
integer/real arithmetic and uninterpreted functions. In that work, we used an
SMT solver and an algorithm similar to k-induction to establish the
realizability of a contract, and justified our approach via a hand proof. Given
the central importance of realizability to our virtual integration approach, we
wanted additional confidence that our approach was sound. This paper describes
a complete formalization of the approach in the Coq proof and specification
language. During formalization, we found several small mistakes and missing
assumptions in our reasoning. Although these did not compromise the correctness
of the algorithm used in the checking tools, they point to the value of
machine-checked formalization. In addition, we believe this is the first
machine-checked formalization for a realizability algorithm.Comment: 14 pages, 1 figur
Formalising Mathematics in Simple Type Theory
Despite the considerable interest in new dependent type theories, simple type
theory (which dates from 1940) is sufficient to formalise serious topics in
mathematics. This point is seen by examining formal proofs of a theorem about
stereographic projections. A formalisation using the HOL Light proof assistant
is contrasted with one using Isabelle/HOL. Harrison's technique for formalising
Euclidean spaces is contrasted with an approach using Isabelle/HOL's axiomatic
type classes. However, every formal system can be outgrown, and mathematics
should be formalised with a view that it will eventually migrate to a new
formalism
The Effects of Foam Rolling and Static Stretching on Flexibility and Acute Muscle Soreness
Please view abstract in the attached PDF file
Criterion Validity of a Field-Based Assessment of Aerobic Capacity in Wheelchair Rugby Athletes
Purpose: To confirm whether peak aerobic capacity determined during laboratory testing could be replicated during an on-court field-based test in wheelchair rugby (WR) players. Methods: Sixteen WR players performed an incremental speed-based peak oxygen uptake (V̇O2peak) test on a motorised treadmill (TM) and completed a Multi-stage Fitness Test (MFT) on a basketball court in a counter-balanced order while spirometric data were recorded. A paired t-test was performed to check for systematic error between tests. A Bland-Altman plot for V̇O2peak illustrated the agreement between the TM and MFT results and how this related to the boundaries of practical equivalence. Results: No significant differences between mean V̇O2peak were reported (TM:1.85±0.63 vs. MFT: 1.81±0.63 L.min-1; p=0.33). Bland-Altman plot for V̇O2peak suggests that the mean values are in good agreement at the group level; i.e., the exact 95% confidence limits for the ratio systematic error (0.95 to 1.02) are within the boundaries of practical equivalence (0.88 to 1.13) showing the group average TM and MFT values are interchangeable. However, consideration of the data at the level of the individual athlete suggests the TM and MFT results were not interchangeable because the 95% ratio limits of agreement either coincide with the boundaries of practical equivalence (upper limit) or fall outside (lower limit). Conclusions: Results suggest that the MFT provides a suitable test at a group level with this cohort of WR players for the assessment of V̇O2peak (range 0.97 – 3.64 L∙min-1), yet caution is noted for interchangeable use of values between tests for individual players
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