scholarly journals Universal Prediction Band Via Semi-Definite Programming

2021 ◽  
Author(s):  
Tengyuan Liang
Keyword(s):  
Universal Prediction ◽  
Prediction Band

scholarly journals Fatigue Stress-Life Model of RC Beams Based on an Accelerated Fatigue Method

2019 ◽  
Vol 4 (2) ◽  
pp. 16
Author(s):  
Eljufout ◽  
Toutanji ◽  
Al-Qaralleh
Keyword(s):  
Cyclic Loading ◽  
Fatigue Testing ◽  
Three Dimensional ◽  
Rc Beam ◽  
Rc Beams ◽  
Testing Methods ◽  
Load Range ◽  
Fatigue Stress ◽  
Life Model ◽  
Prediction Band

Several standard fatigue testing methods are used to determine the fatigue stress-life prediction model (S-N curve) and the endurance limit of Reinforced Concrete (RC) beams, including the application of constant cyclic tension-tension loads at different stress or strain ranges. The standard fatigue testing methods are time-consuming and expensive to perform, as a large number of specimens is needed to obtain valid results. The purpose of this paper is to examine a fatigue stress-life predication model of RC beams that are developed with an accelerated fatigue approach. This approach is based on the hypothesis of linear accumulative damage of the Palmgren–Miner rule, whereby the applied cyclic load range is linearly increased with respect to the number of cycles until the specimen fails. A three-dimensional RC beam was modeled and validated using ANSYS software. Numerical simulations were performed for the RC beam under linearly increased cyclic loading with different initial loading conditions. A fatigue stress-life model was developed that was based on the analyzed data of three specimens. The accelerated fatigue approach has a higher rate of damage accumulations than the standard testing approach. All of the analyzed specimens failed due to an unstable cracking of concrete. The developed fatigue stress-life model fits the upper 95% prediction band of RC beams that were tested under constant amplitude cyclic loading.

scholarly journals Robust Universal Inference

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 773
Author(s):  
Amichai Painsky ◽  
Meir Feder
Keyword(s):  
Robust Estimation ◽  
Minimax Estimator ◽  
Worst Case ◽  
Capacity Theory ◽  
Alternative Approach ◽  
True Model ◽  
Finite Set ◽  
Universal Prediction ◽  
Estimation Scheme

Learning and making inference from a finite set of samples are among the fundamental problems in science. In most popular applications, the paradigmatic approach is to seek a model that best explains the data. This approach has many desirable properties when the number of samples is large. However, in many practical setups, data acquisition is costly and only a limited number of samples is available. In this work, we study an alternative approach for this challenging setup. Our framework suggests that the role of the train-set is not to provide a single estimated model, which may be inaccurate due to the limited number of samples. Instead, we define a class of “reasonable” models. Then, the worst-case performance in the class is controlled by a minimax estimator with respect to it. Further, we introduce a robust estimation scheme that provides minimax guarantees, also for the case where the true model is not a member of the model class. Our results draw important connections to universal prediction, the redundancy-capacity theorem, and channel capacity theory. We demonstrate our suggested scheme in different setups, showing a significant improvement in worst-case performance over currently known alternatives.

Universal prediction

1998 ◽  
Vol 44 (6) ◽  
pp. 2124-2147 ◽  
Author(s):  
N. Merhav ◽  
M. Feder
Keyword(s):  
Universal Prediction

scholarly journals Universal predictability of mobility patterns in cities

2014 ◽  
Vol 11 (100) ◽  
pp. 20140834 ◽  
Author(s):  
Xiao-Yong Yan ◽  
Chen Zhao ◽  
Ying Fan ◽  
Zengru Di ◽  
Wen-Xu Wang
Keyword(s):  
Spatial Scales ◽  
Human Mobility ◽  
Mobility Patterns ◽  
Mobility Data ◽  
Universal Prediction ◽  
Potential Applications ◽  
Mobility Behaviour ◽  
History Of ◽  
Different Characteristics ◽  
The City

Despite the long history of modelling human mobility, we continue to lack a highly accurate approach with low data requirements for predicting mobility patterns in cities. Here, we present a population-weighted opportunities model without any adjustable parameters to capture the underlying driving force accounting for human mobility patterns at the city scale. We use various mobility data collected from a number of cities with different characteristics to demonstrate the predictive power of our model. We find that insofar as the spatial distribution of population is available, our model offers universal prediction of mobility patterns in good agreement with real observations, including distance distribution, destination travel constraints and flux. By contrast, the models that succeed in modelling mobility patterns in countries are not applicable in cities, which suggests that there is a diversity of human mobility at different spatial scales. Our model has potential applications in many fields relevant to mobility behaviour in cities, without relying on previous mobility measurements.

Internationalization and failure risk patterns

2019 ◽  
Vol 29 (1) ◽  
pp. 25-43 ◽  
Author(s):  
Oliver Lukason ◽  
Tiia Vissak
Keyword(s):  
Financial Performance ◽  
Statistical Tests ◽  
European Market ◽  
Content Type ◽  
Failure Risk ◽  
Single European Market ◽  
Medium Risk ◽  
Universal Prediction ◽  
Export Shares ◽  
Target Markets

PurposeThis paper aims to find out what kind of export and failure risk patterns exist among young Estonian manufacturing exporters and explore their interlinkages.Design/methodology/approachThe sample consisted of 208 young Estonian manufacturing exporters. Based on internationalization literature, export patterns were detected with a consecutive three-stage clustering of export sales share from total sales, outside-Europe sales share from export sales and number of target markets, while failure risk patterns were detected by clustering failure probabilities obtained from a universal prediction model. The interconnection of export patterns with financial ratios and failure risk patterns was studied with statistical tests.FindingsSix main internationalization patterns existed. In all, 49 per cent of firms exported to a single European market and their export share was constantly very low, while even most of the firms with high export shares (39 per cent of the sample) were also active on one European market. In terms of failure risk patterns, 49 per cent of firms had constantly very low failure risk, while 51 per cent of firms had medium risk. Higher export engagement did not lead to better financial performance or lower failure risk.Originality/valueThis study is the first to find out if firms following different export patterns are also characterized by specific financial performance and failure risk. In addition, studies encompassing young exporters’ specific target markets and failure risk development are rare. While exporters’ and non-exporters’ financial performance differences have been frequently documented in favor of the former, this study found no such differences for different types of young exporters.

Targeting tumour markers: What makes therapy discriminating?

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 13129-13129
Author(s):  
K. Johnson ◽  
R. Ward
Keyword(s):  
Response Rate ◽  
Tumour Response ◽  
Response Rates ◽  
Tumour Markers ◽  
Targeted Drugs ◽  
Rate Difference ◽  
Survival Gain ◽  
First Line Therapy ◽  
Limited Effectiveness ◽  
Prediction Band

13129 Background: Therapy in inoperable non-small cell lung cancer has limited effectiveness. New therapy directed at tumour markers is attractive but limited by marker prevalence and intrinsic effectiveness. Prior work (Abstract 9639, 2005 PASCO) on 191 trials of first line therapy shows a “typical drug” needs at least a 35% difference in response rate, treatment versus control, to predict a survival gain. The current work describes the characteristics of targeted drugs likely to predict this gain at smaller differences, i.e., more discriminating drugs. We determine how much greater effects on response rate and survival, compared to the typical drug, need to be to predict this survival gain. Methods: By using 1.0, 1.1, 1.2, 2.0-fold increments in response rates over traditional therapy and the same increments for median survival up to that used for response, we defined 55 differently constructed targeted drugs. The drugs were all analysed at each of four marker prevalence rates, 5%, 20%, 50% and 100%, each analysis determining the response rate difference needed to predict a survival gain. For each analysis individual trial response rates were modified in one arm before applying linear regression. The response rate difference to predict a survival gain is the portion of the prediction band fully exceeding zero. Results: Improvements in discrimination were rare and highly sensitive to marker prevalence. Little improvement occurred for any drug with 5% or 20% prevalence, and if no survival improvement occurred, discrimination worsened (up to 90%). If both tumour response and survival were doubled, discrimination improved to 33%, 27%, 17%, and 7% for marker prevalence of 5%, 20%, 50%, or 100%, respectively. Modest changes (×1.4, ×1.6) in response and survival only improved discrimination with 100% prevalence. Clearly improved discrimination (to 20% or less) only occurred with at least ×1.8 increase in response and survival and 50% or more prevalence. Conclusions: The results show that targeting a marker only substantially improves discrimination if it doubles both tumour response rate and median overall survival and if marker prevalence is at least 50%. This approach may help rationalize aspects of drug development in oncology. No significant financial relationships to disclose.

Adaptive coefficient scanning based on universal prediction

2009 ◽  
Vol 45 (25) ◽  
pp. 1302
Author(s):  
S.-J. Baek ◽  
C.-S. Park ◽  
S.-W. Jung ◽  
H.-M. Nam ◽  
S.-J. Ko
Keyword(s):  
Universal Prediction
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