10 results
Search Results
2. The Minkowski inequalities via generalized proportional fractional integral operators.
- Author
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Rahman, Gauhar, Khan, Aftab, Abdeljawad, Thabet, and Nisar, Kottakkaran Sooppy
- Subjects
FRACTIONAL integrals ,FRACTIONAL calculus ,INTEGRAL operators ,INTEGRAL inequalities ,KERNEL functions ,EXPONENTIAL functions ,MATHEMATICAL equivalence - Abstract
Recent research has gained more attention on conformable integrals and derivatives to derive the various type of inequalities. One of the recent advancements in the field of fractional calculus is the generalized nonlocal proportional fractional integrals and derivatives lately introduced by Jarad et al. (Eur. Phys. J. Special Topics 226:3457–3471, 2017) comprising the exponential functions in the kernels. The principal aim of this paper is to establish reverse Minkowski inequalities and some other fractional integral inequalities by utilizing generalized proportional fractional integrals. Also, two new theorems connected with this inequality as well as other inequalities associated with the generalized proportional fractional integrals are established. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
3. Exponential growth in the number of words used for the European Common Fisheries Policy (CFP): Does better management require more text?
- Author
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Pastoors, M.A.
- Subjects
FISHERY policy ,EXPONENTIAL functions ,FISHERIES ,FISHERY management ,FISHERIES & the environment - Abstract
Abstract: The European Common Fisheries Policy (CFP) is a common policy that originates from 1983 and has been renewed every 10 years. The policy generally aims for sustainable fisheries in terms of living resources, economics and social aspects. The most recent version of the policy was agreed in co-decision by the European Parliament and the European Council of Ministers in 2013. The CFP has often been criticised for not delivering on the objectives and for developing into micro-management with very detailed regulations. In this paper, the evolution of the CFP has been analysed using a simple word-count indicator. The results show a strong increase in the number of words used to describe the basic regulation of the CFP from 3500 words in 1983 to 21,000 words in the agreed regulation in 2013. The expansion of words fits closely to an exponential growth curve. The co-decision process between the European Parliament and the Council showed a 55% increase in words and the article describing the new landing obligation showed a 360% increase in words. First reports on the new CFP have already shown that the complexity in the regulation could increase the likelihood of misunderstanding and suboptimal decisions. Word-counts are obviously a crude way to measure regulatory complexity but they are easy to generate and intuitive to understand to different audiences. The challenge is to create conceptual models that can link this intuitive indicator into an empirical framework that attempts to measure the relative regulatory complexity. [Copyright &y& Elsevier]
- Published
- 2014
- Full Text
- View/download PDF
4. Modeling and forecasting the spread of COVID-19 with stochastic and deterministic approaches: Africa and Europe.
- Author
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Atangana, Abdon and İğret Araz, Seda
- Subjects
COVID-19 ,FORECASTING ,STATISTICS ,STOCHASTIC systems ,EXPONENTIAL functions - Abstract
Using the existing collected data from European and African countries, we present a statistical analysis of forecast of the future number of daily deaths and infections up to 10 September 2020. We presented numerous statistical analyses of collected data from both continents using numerous existing statistical theories. Our predictions show the possibility of the second wave of spread in Europe in the worse scenario and an exponential growth in the number of infections in Africa. The projection of statistical analysis leads us to introducing an extended version of the well-blancmange function to further capture the spread with fractal properties. A mathematical model depicting the spread with nine sub-classes is considered, first converted to a stochastic system, where the existence and uniqueness are presented. Then the model is extended to the concept of nonlocal operators; due to nonlinearity, a modified numerical scheme is suggested and used to present numerical simulations. The suggested mathematical model is able to predict two to three waves of the spread in the near future. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
5. Accounting for spatiotemporal correlations of GNSS coordinate time series to estimate station velocities.
- Author
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Benoist, C., Collilieux, X., Rebischung, P., Altamimi, Z., Jamet, O., Métivier, L., Chanard, K., and Bel, L.
- Subjects
- *
TIME series analysis , *SURFACE waves (Seismic waves) , *SPATIAL filters , *EXPONENTIAL functions , *VELOCITY , *FORECASTING , *WHITE noise - Abstract
GNSS coordinate time series provided by the International GNSS Service are spatially correlated. Spatiotemporal covariance models of the GNSS coordinate time series can be used to improve the estimation of station velocities. Modeling the spatiotemporal correlations by exponential functions and adding spatial white noise is shown to improve the velocity determination of short GNSS coordinate series for a tested subset of 21 stations. The new method performs similarly to standard spatial filtering of the time series but can be improved in the future by a more reliable modeling of the coordinate spatiotemporal correlations. It is well known that GNSS permanent station coordinate time series exhibit time-correlated noise. Spatial correlations between coordinate time series of nearby stations are also long-established and generally handled by means of spatial filtering techniques. Accounting for both the temporal and spatial correlations of the noise via a spatiotemporal covariance model is however not yet a common practice. We demonstrate in this paper the interest of using such a spatiotemporal covariance model of the stochastic variations in GNSS time series in order to estimate long-term station coordinates and especially velocities. We provide a methodology to rigorously assess the covariances between horizontal coordinate variations and use it to derive a simple exponential spatiotemporal covariance model for the stochastic variations in the IGS repro2 station coordinate time series. We then use this model to estimate station velocities for two selected datasets of 10 time series in Europe and 11 time series in the USA. We show that coordinate prediction as well as velocity determination from short time series are improved when using this spatiotemporal model, as compared with the case where spatiotemporal correlations are ignored. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
6. Assessing the degree of detail of temperature-based snow routines for runoff modelling in mountainous areas in central Europe.
- Author
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Girons Lopez, Marc, Vis, Marc J. P., Jenicek, Michal, Griessinger, Nena, and Seibert, Jan
- Subjects
RUNOFF models ,HYDROLOGIC cycle ,SNOW ,EXPONENTIAL functions ,ORDER picking systems - Abstract
Snow processes are a key component of the water cycle in mountainous areas as well as in many areas of the mid and high latitudes of the Earth. The complexity of these processes, coupled with the limited data available on them, has led to the development of different modelling approaches aimed at improving our understanding of these processes and supporting decision-making and management practices. Physically based approaches, such as the energy balance method, provide the best representation of snow processes, but limitations in data availability in many situations constrain their applicability in favour of more straightforward approaches. Indeed, the comparatively simple temperature-index method has become the most widely used modelling approach for representing snowpack processes in rainfall-runoff modelling, with different variants of this method implemented across many models. Nevertheless, the decisions on the most suitable degree of detail of the model are in many cases not adequately assessed for a given application. In this study we assessed the suitability of a number of formulations of different components of the simple temperature-index method for rainfall-runoff modelling in mountainous areas of central Europe by using the Hydrologiska Byråns Vattenbalansavdelning (HBV) bucket-type model. To this end, we reviewed the most widely used formulations of different components of temperature-based snow routines from different rainfall-runoff models and proposed a series of modifications to the default structure of the HBV model. We narrowed the choice of alternative formulations to those that provide a simple conceptualisation of the described processes in order to constrain parameter and model uncertainty. We analysed a total of 64 alternative snow routine structures over 54 catchments using a split-sample test. Overall, the most valuable modifications to the standard structure of the HBV snow routine were (a) using an exponential snowmelt function coupled with no refreezing and (b) computing melt rates with a seasonally variable degree-day factor. Our results also demonstrated that increasing the degree of detail of the temperature-based snow routines in rainfall-runoff models did not necessarily lead to an improved model performance per se. Instead, performing an analysis on which processes are to be included, and to which degree of detail, for a given model and application is a better approach to obtain more reliable and robust results. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
7. The role of Airbnb creating a "new"-old city centre: facts, problems and controversies in Porto.
- Author
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Chamusca, Pedro, Rio Fernandes, José, Carvalho, Luís, and Mendes, Thiago
- Subjects
URBAN tourism ,SHARING economy ,URBAN growth ,EXPONENTIAL functions ,LOCAL government - Abstract
Copyright of Boletín de la Asociación de Geógrafos Españoles is the property of Asociacion de Geografos Espanoles and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
- Full Text
- View/download PDF
8. Bibliometric analysis of simulated driving research from 1997 to 2016.
- Author
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Guo, Fu, Lv, Wei, Liu, Li, Wang, Tianbo, and Duffy, Vincent G.
- Subjects
DISTRACTED driving ,BIBLIOTHERAPY ,INFORMATION retrieval ,EXPONENTIAL functions ,PHARMACOLOGY ,NEUROLOGICAL disorders ,AUTOMOBILE driving simulators ,AUTOMOBILE driving ,BIBLIOMETRICS ,COMPARATIVE studies ,RESEARCH methodology ,MEDICAL cooperation ,PSYCHOLOGY of movement ,PUBLISHING ,RESEARCH ,TRANSPORTATION ,USER interfaces ,EVALUATION research - Abstract
Objective: The objective of this study was to explore the evolution footprints of simulated driving research in the past 20 years through rigorous and systematic bibliometric analysis, to provide insights regarding when and where the research was performed and by whom and how the mainstream content evolved over the years.Methods: The analysis began with data retrieval in Web of Science with defined search terms related to simulated driving. BibExcel and CiteSpace were employed to conduct the performance analysis and co-citation network analysis; that is, probe of the performance of institutes, journals, authors, and research hotspots.Results: A total of 3,766 documents were filtered out and presented an exponential growth from 1997 to 2016. The United States contributed the most publications as well as international collaborations followed by Germany and China. In addition, several universities in The Netherlands and the United States dominated the list of contributing institutes. The leading journals were in transportation and ergonomics. The leading researchers were also recognized among the 8,721 contributing authors, such as J. D. Lee, D. L. Fisher, J. H. Kim, and K. A. Brookhuis. Finally, the co-citation analysis illuminated the evolution of simulated driving research that covered the following topics roughly in chronological order: task-induced stress, drivers with neurological disorders, alertness and sleepiness while driving, trust toward driving assistance systems, driver distraction, the effect of drug use, the validity of simulators, and automated driving.Conclusions: This article employed bibliometric tools to probe the contributing countries, institutes, journals, authors, and mainstream hotspots of simulated driving research in the past 20 years. A systematic bibliometric analysis of this field will help researchers realize the panorama of global simulated driving and establish future research directions. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
9. Efficient static replication of European options under exponential Lévy models.
- Author
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TAKAHASHI, AKIHIKO and YAMAZAKI, AKIRA
- Subjects
RESEARCH ,EXPONENTIAL functions ,PORTFOLIOS in education ,SERIAL publications ,LIBRARY materials ,REPLICATION (Experimental design) ,SECONDARY analysis ,LIBRARY inventories - Abstract
This study proposes a new scheme for the static replication of European options and their portfolios. First, a general approximation formula for efficient static replication as an extension of Carr P. and Chou A. (1997, 2002) and Carr P. and Wu L. (2002) is derived. Second, a concrete procedure for implementing the scheme by applying it to plain vanilla options under exponential Lévy models is presented. Finally, numerical examples in a model developed by Carr, P., Geman, H., Madan, D., and Yor M. (2002) are used to demonstrate that the replication scheme is more efficient and more effective in practice than a standard static replication method. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 29:1–15, 2009 [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
10. Bat population recoveries give insight into clustering strategies during hibernation.
- Author
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Martínková, Natália, Baird, Stuart J. E., Káňa, Vlastislav, and Zima, Jan
- Subjects
HIBERNATION ,HORSESHOE bats ,BATS ,MYOTIS ,ENERGY conservation ,EXPONENTIAL functions - Abstract
Background: Behaviour during hibernation contributes to energy conservation in winter. Hibernating bats select roosts with respect to physiological and environmental stressors, available local microclimate and species-specific requirements. Results: We found that, in the period between 1977 and 2018, hibernating Myotis myotis and Rhinolophus hipposideros bats showed exponential population growth. The growth rates, corrected for local winter seasonal severity and winter duration, were equal to 10 and 13%, respectively. While R. hipposideros only utilised the thermally stable and, at survey time, warmer corridors in the hibernaculum, an increasing proportion of M. myotis roosted in the thermally stable corridors as their abundance increased. About 14% of all hibernating M. myotis displayed solitary roosting, irrespective of other covariates. Those bats that clustered together formed progressively larger clusters with increasing abundance, particularly in cold corridors. We found no statistically significant relationship for clustering behaviour or cluster size with winter severity or winter duration. Conclusions: Abundance of hibernating bats is increasing in Central Europe. As the number of M. myotis bats increases, thermally unstable corridors become saturated with large clusters and the animals begin to roost deeper underground. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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