1,122 research outputs found
Study on Mooring Design and Calculation Method of Ocean Farm Based on Time-Domain Potential Flow Theory
In order to calculate the mooring force of a new semi-submerged Ocean Farm quickly and accurately, based on the unsteady time-domain potential flow theory and combined the catenary model, the control equation of mooring cable is established, and the mooring force of the platform under the wave spectrum is calculated. First of all, based on the actual situation of the ocean environment and platform, the mooring design of the platform is carried out, and the failure analysis and sensitivity analysis of the single anchor chain by the time domain coupling method are adopted: including different water depth, cycle, pretension size, anchor chain layout direction and wind speed, etc. The analysis results confirm the reliability of anchoring method. Based on this, the mooring point location of the platform is determined, the force of each anchor chain in the anchoring process is calculated, and the mooring force and the number of mooring cables are obtained for each cable that satisfies the specification, the results of this paper can provide theoretical calculation methods for mooring setting and mooring force calculation of similar offshore platforms
Constructing Synthetic Treatment Groups without the Mean Exchangeability Assumption
The purpose of this work is to transport the information from multiple
randomized controlled trials to the target population where we only have the
control group data. Previous works rely critically on the mean exchangeability
assumption. However, as pointed out by many current studies, the mean
exchangeability assumption might be violated. Motivated by the synthetic
control method, we construct a synthetic treatment group for the target
population by a weighted mixture of treatment groups of source populations. We
estimate the weights by minimizing the conditional maximum mean discrepancy
between the weighted control groups of source populations and the target
population. We establish the asymptotic normality of the synthetic treatment
group estimator based on the sieve semiparametric theory. Our method can serve
as a novel complementary approach when the mean exchangeability assumption is
violated. Experiments are conducted on synthetic and real-world datasets to
demonstrate the effectiveness of our methods
The Cross-Section of Volatility and Expected Returns
We examine the pricing of aggregate volatility risk in the cross-section of stock returns. Consistent with theory, we find that stocks with high sensitivities to innovations in aggregate volatility have low average returns. In addition, we find that stocks with high idiosyncratic volatility relative to the Fama and French (1993) model have abysmally low average returns. This phenomenon cannot be explained by exposure to aggregate volatility risk. Size, book-to-market, momentum, and liquidity effects cannot account for either the low average returns earned by stocks with high exposure to systematic volatility risk or for the low average returns of stocks with high idiosyncratic volatility.
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
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