Truncated Models for Probabilistic Weighted Retrieval

2022 ◽  
Vol 40 (3) ◽  
pp. 1-24
Author(s):  
Jiaul H. Paik ◽  
Yash Agrawal ◽  
Sahil Rishi ◽  
Vaishal Shah
Keyword(s):  
Performance Improvement ◽  
Upper Bound ◽  
Probabilistic Models ◽  
Modeling Error ◽  
Large Magnitude ◽  
Retrieval Models ◽  
Document Collections ◽  
Probabilistic Retrieval ◽  
Two Factors ◽  
Significant Performance

Existing probabilistic retrieval models do not restrict the domain of the random variables that they deal with. In this article, we show that the upper bound of the normalized term frequency ( tf ) from the relevant documents is much smaller than the upper bound of the normalized tf from the whole collection. As a result, the existing models suffer from two major problems: (i) the domain mismatch causes data modeling error, (ii) since the outliers have very large magnitude and the retrieval models follow tf hypothesis, the combination of these two factors tends to overestimate the relevance score. In an attempt to address these problems, we propose novel weighted probabilistic models based on truncated distributions. We evaluate our models on a set of large document collections. Significant performance improvement over six existing probabilistic models is demonstrated.

Consideration of structural constraints in passive rotor blade design for improved performance

2015 ◽  
Vol 119 (1222) ◽  
pp. 1513-1539 ◽  
Author(s):  
J. W. Lim
Keyword(s):  
Performance Improvement ◽  
Rotor Blade ◽  
Parametric Design ◽  
Control Point ◽  
Bending Moment ◽  
Structural Constraints ◽  
Design Variables ◽  
Significant Performance ◽  
Structural Redesign ◽  
Improved Performance

AbstractThis design study applied parameterisation to rotor blade for improved performance. In the design, parametric equations were used to represent blade planform changes over the existing rotor blade model. Design variables included blade twist, sweep, dihedral, and radial control point. Updates to the blade structural properties with changes in the design variables allowed accurate evaluation of performance objectives and realistic structural constraints – blade stability, steady moments (flap bending, chord bending, and torsion), and the high g manoeuvring pitch link loads. Performance improvement was demonstrated with multiple parametric designs. Using a parametric design with advanced aerofoils, the predicted power reduction was 1·0% in hover, 10·0% at μ = 0·30, and 17·0% at μ = 0·40 relative to the baseline UH-60A rotor, but these were obtained with a 35% increase in the steady chord bending moment at μ = 0·30 and a 20% increase in the half peak-to-peak pitch link load during the UH-60A UTTAS manoeuvre Low vibration was maintained for this design. More rigorous design efforts, such as chord tapering and/or structural redesign of the blade cross section, would enlarge the feasible design space and likely provide significant performance improvement.

scholarly journals Optimized distributed systems achieve significant performance improvement on sorted merging of massive VCF files

GigaScience ◽  
2018 ◽  
Vol 7 (6) ◽  
Author(s):  
Xiaobo Sun ◽  
Jingjing Gao ◽  
Peng Jin ◽  
Celeste Eng ◽  
Esteban G Burchard ◽  
...  
Keyword(s):  
Distributed Systems ◽  
Performance Improvement ◽  
Significant Performance

Fiber nonlinearity compensation using optical phase conjugation in dispersion-managed coherent transmission systems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jinqing Hao ◽  
Bingchen Han
Keyword(s):  
Performance Improvement ◽  
System Performance ◽  
Optical Transmission ◽  
Phase Conjugation ◽  
Fiber Amplifiers ◽  
Transmission Systems ◽  
Fiber Nonlinearity ◽  
Erbium Doped ◽  
Significant Performance ◽  
Transmission Link

Abstract In the discretely amplified transmission systems with erbium-doped fiber amplifiers, the system performance of nonlinearity-compensated optical transmission based on pre-dispersed spectral inversion (PSI) is investigated numerically. We find that PSI offers more significant performance improvement in dispersion-managed (DM) links than that in non-dispersion-managed (noDM) links. On the other hand, the DM link is more sensitive to the span offset from the center of the transmission link than noDM link. The performance difference between DM and noDM links is 1 dB if the span offset equals four spans in 20 × 90 km nonlinear transmission. Furthermore, we show that for the dispersion-managed transmission, in order to obtain the best system performance, the amount of pre-dispersion of the PSI, should be optimized over different dispersion maps.

scholarly journals Arabic Query Expansion Using WordNet and Association Rules

2016 ◽  
Vol 12 (3) ◽  
pp. 51-64 ◽  
Author(s):  
Ahmed Abbache ◽  
Farid Meziane ◽  
Ghalem Belalem ◽  
Fatma Zohra Belkredim
Keyword(s):  
Performance Improvement ◽  
Association Rules ◽  
Query Expansion ◽  
Arabic Language ◽  
Selection Method ◽  
Retrieval Performance ◽  
Retrieval Systems ◽  
Information Retrieval Systems ◽  
Significant Performance ◽  
Selection Of

Query expansion is the process of adding additional relevant terms to the original queries to improve the performance of information retrieval systems. However, previous studies showed that automatic query expansion using WordNet do not lead to an improvement in the performance. One of the main challenges of query expansion is the selection of appropriate terms. In this paper, the authors review this problem using Arabic WordNet and Association Rules within the context of Arabic Language. The results obtained confirmed that with an appropriate selection method, the authors are able to exploit Arabic WordNet to improve the retrieval performance. Their empirical results on a sub-corpus from the Xinhua collection showed that their automatic selection method has achieved a significant performance improvement in terms of MAP and recall and a better precision with the first top retrieved documents.

Consideration of structural constraints in passive rotor blade design for improved performance

2016 ◽  
Vol 120 (1232) ◽  
pp. 1604-1631 ◽  
Author(s):  
J.W. Lim
Keyword(s):  
Performance Improvement ◽  
Rotor Blade ◽  
Parametric Design ◽  
Control Point ◽  
Bending Moment ◽  
Structural Constraints ◽  
Design Variables ◽  
Significant Performance ◽  
Structural Redesign ◽  
Improved Performance

ABSTRACTThis design study applied parameterisation to rotor blade for improved performance. In the design, parametric equations were used to represent blade planform changes over the existing rotor blade model. Design variables included blade twist, sweep, dihedral and the radial control point. Updates to the blade structural properties with changes in the design variables allowed accurate evaluation of performance objectives and realistic structural constraints – blade stability, steady moments (flap bending, chord bending and torsion) and the high-g manoeuvre pitch link loads. Performance improvement was demonstrated with multiple parametric designs. Using a parametric design with advanced aerofoils, the predicted power reduction was 1.0% in hover, 10.0% at μ = 0.30 and 17.0% at μ = 0.40, relative to the baseline UH-60A rotor, but these were obtained with a 35% increase in the steady chord bending moment at μ = 0.30 and a 20% increase in the half peak-to-peak pitch link load during the UH-60A UTTAS manoeuvre. Low vibration was maintained for this design. More rigorous design efforts, such as chord tapering and/or structural redesign of the blade cross section, would enlarge the feasible design space and likely provide significant performance improvement.

scholarly journals Narrowing the Range of Future Climate Projections Using Historical Observations of Atmospheric CO2

2017 ◽  
Vol 30 (8) ◽  
pp. 3039-3053 ◽  
Author(s):  
Ben B. B. Booth ◽  
Glen R. Harris ◽  
James M. Murphy ◽  
Jo I. House ◽  
Chris D. Jones ◽  
...  
Keyword(s):  
First Century ◽  
System Model ◽  
Climate Projections ◽  
Magnitude Response ◽  
Large Magnitude ◽  
Strong Constraint ◽  
Two Factors ◽  
Perturbed Model ◽  
The Impact ◽  
Climate Responses

Uncertainty in the behavior of the carbon cycle is important in driving the range in future projected climate change. Previous comparisons of model responses with historical CO2 observations have suggested a strong constraint on simulated projections that could narrow the range considered plausible. This study uses a new 57-member perturbed parameter ensemble of variants of an Earth system model for three future scenarios, which 1) explores a wider range of potential climate responses than before and 2) includes the impact of past uncertainty in carbon emissions on simulated trends. These two factors represent a more complete exploration of uncertainty, although they lead to a weaker constraint on the range of future CO2 concentrations as compared to earlier studies. Nevertheless, CO2 observations are shown to be effective at narrowing the distribution, excluding 30 of 57 simulations as inconsistent with historical CO2 changes. The perturbed model variants excluded are mainly at the high end of the future projected CO2 changes, with only 8 of the 26 variants projecting RCP8.5 2100 concentrations in excess of 1100 ppm retained. Interestingly, a minority of the high-end variants were able to capture historical CO2 trends, with the large-magnitude response emerging later in the century (owing to high climate sensitivities, strong carbon feedbacks, or both). Comparison with observed CO2 is effective at narrowing both the range and distribution of projections out to the mid-twenty-first century for all scenarios and to 2100 for a scenario with low emissions.

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