Prediction of the Number of International Tourists in China Based on Gray Model (1,1)

2009 ◽  
Author(s):  
Yang Lingbin ◽  
Zhang Xia ◽  
Wu Jin
Keyword(s):  
Gray Model

Research on Power Transformer Fault Forecast

2011 ◽  
Vol 204-210 ◽  
pp. 1553-1558
Author(s):  
Rui Rui Zheng ◽  
Ji Yin Zhao ◽  
Min Li ◽  
Bao Chun Wu
Keyword(s):  
Time Series ◽  
Fault Location ◽  
Power Transformer ◽  
Forecast Model ◽  
Ratio Method ◽  
Gray Model ◽  
Artificial Immune ◽  
Diagnosis Method ◽  
Type Data ◽  
Transformer Fault

To forecast power transformer fault, this paper proposed a integrated algorithm. Research found that discrete time series of power transformer dissolved gases concentration have 2 main types: the s type and the monotone increasing type. The gray verhulst model was chosen for forecasting the s type series, while the gray model predicted the monotone increasing type data. The two models combined a new integrated forecast model. The fault diagnosis method combines the improved three-ratio method and gray artificial immune algorithm, so it can diagnoses both single and multi power transformer faults, and give the fault location. Experiments show that the power transformer fault forecast algorithm is effective and reliable.

Real-world observational study of assessment of CHA2DS2-VASc, C2HEST and HAVOC scores for atrial fibrillation among patients with rheumatological disorders: a nationwide analysis

2021 ◽  
pp. postgradmedj-2021-140754
Author(s):  
Wei Syun Hu ◽  
Cheng Li Lin
Keyword(s):  
Atrial Fibrillation ◽  
Retrospective Study ◽  
Predictive Models ◽  
Operating Characteristic ◽  
Predictive Accuracy ◽  
Scoring Systems ◽  
Gray Model ◽  
Discriminative Ability ◽  
Discriminatory Ability ◽  
Rheumatological Disease

PurposeThis is a nationwide-based retrospective study aiming to compare the three different scoring systems (CHA2DS2-VASc, C2HEST and HAVOC scores) in the prediction of atrial fibrillation (AF) in patients with rheumatological disease.MethodsWe used the Fine and Gray model to estimate the risk of AF (subhazard ratio and 95% CI). The predictive accuracy and discriminatory ability of the predictive model were evaluated by receiver operating characteristic (ROC) curve.ResultsAmong the three predictive models, the model using CHA2DS2-VASc score had the better discriminative ability with an ROC of 0.79. The model with C2HEST score had an ROC of 0.78. The discriminative ability of the HAVOC score was 0.77, estimated by ROC.ConclusionWe concluded the CHA2DS2-VASc score has better performance in predicting AF compared with C2HEST score or HAVOC score.

Analysis of the Temperature Profile of Ceramic Composite Materials Exposed to Combined Conduction–Radiation Between Concentric Cylinders

1998 ◽  
Vol 120 (2) ◽  
pp. 271-275 ◽  
Author(s):  
A. Tremante ◽  
F. Malpica
Keyword(s):  
Ceramic Composite ◽  
Numerical Study ◽  
Thermal Characteristics ◽  
Ceramic Matrix Composites ◽  
Gray Model ◽  
Matrix Composites ◽  
Semitransparent Materials ◽  
Concentric Cylinders ◽  
Benchmark Solutions ◽  
Potential Use

A numerical study is made of the thermal characteristics of semitransparent materials exposed to simultaneous conduction and radiation between concentric cylinders. For extremely high-temperature applications, where radiative transfer plays an important role, ceramic-matrix composites, considered as semitransparent materials, are being explored for potential use in turbine and compressor components, spacecraft structures, engine control systems and nuclear reactors. Through the use of a gray model and the two-flux method, specialized equations are developed that generate a system of nonlinear ordinary differential equations. To facilitate the solution of this system, an iterative strategy is adopted. In order to demonstrate the versatility and accuracy of the proposed methodology, the results of several numerical experiments are presented and compared with benchmark solutions.

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