1,797 research outputs found
Accelerate sampling in atomistic energy landscapes using topology-based coarse-grained models
We describe a multiscale enhanced sampling (MSES) method where efficient topology-based coarse-grained models are coupled with all-atom ones to enhance the sampling of atomistic protein energy landscape. The bias from the coupling is removed by Hamiltonian replica exchange, thus allowing one to benefit simultaneously from faster transitions of coarse-grained modeling and accuracy of atomistic force fields. The method is demonstrated by calculating the conformational equilibria of several small but nontrivial β-hairpins with varied stabilities
Numerical Simulation on the Stability of Surrounding Rock of Horizontal Rock Strata in the Tunnel
Horizontal rock strata is a geological condition of rock which is often encountered in the tunnel construction, and it has an important influence on the tunnel construction, it is necessary to analyze and study the stability of horizontal rock strata in tunnel construction to ensure the tunnel construction’s safety and efficiency. By taking “Xishan Highway Tunnel” as the research object, and using the numerical simulation method, the numerical model of the tunnel has been established in the Midas/GTS to simulate the tunnel excavation under the horizontal rock strata condition,and the deformation and failure mechanism of surrounding rock and the influence factors of surrounding rock stability after are studied and analyzed. The research focused on the displacement of surrounding rock horizontal and vertical deformation, the results show that the vertical displacement of the surrounding rock is obviously greater than that of other parts during the excavation of the horizontal rock tunnel. According to the calculation results, the optimization measures of horizontal stratum tunnel construction method are put forward, which has important reference value for ensuring the construction safety and construction quality
Unsupervised Evaluation of Out-of-distribution Detection: A Data-centric Perspective
Out-of-distribution (OOD) detection methods assume that they have test ground
truths, i.e., whether individual test samples are in-distribution (IND) or OOD.
However, in the real world, we do not always have such ground truths, and thus
do not know which sample is correctly detected and cannot compute the metric
like AUROC to evaluate the performance of different OOD detection methods. In
this paper, we are the first to introduce the unsupervised evaluation problem
in OOD detection, which aims to evaluate OOD detection methods in real-world
changing environments without OOD labels. We propose three methods to compute
Gscore as an unsupervised indicator of OOD detection performance. We further
introduce a new benchmark Gbench, which has 200 real-world OOD datasets of
various label spaces to train and evaluate our method. Through experiments, we
find a strong quantitative correlation betwwen Gscore and the OOD detection
performance. Extensive experiments demonstrate that our Gscore achieves
state-of-the-art performance. Gscore also generalizes well with different
IND/OOD datasets, OOD detection methods, backbones and dataset sizes. We
further provide interesting analyses of the effects of backbones and IND/OOD
datasets on OOD detection performance. The data and code will be available
High performance interrogation by a composite-double-probe-pulse for ultra-weak FBG array
We propose and experimentally demonstrate a technique using a composite-double-probe-pulse (CDPP) to eliminate the effect of polarization fading for phase-sensitive optical time-domain reflectometry (Φ-OTDR) based on ultra-weak FBG (UWFBG) array. The CDPP is composed of two optical pulses whose spatial interval is equal to twice the spatial interval of adjacent UWFBGs in the UWFBG array. One optical pulse is a long optical pulse, and the other optical pulse is composed of two continuous short optical pulses, whose polarization states are orthogonal to each other. The width of the short pulse is equal to half of the width of the normal pulse and their frequencies are different from the long pulse. By using such a method to perform the sensing for the UWFBG array, distributed quantitative measurement can be realized with only direct detection scheme and the influence of polarization fading in the demodulation of signal is thoroughly eliminated
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