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Tytuł:
A data-driven approach to predict hydrometeorological variability and fluctuations in lake water levels
Autorzy:
Tan Kesgin, Remziye I.
Demir, Ibrahim
Kesgin, Erdal
Abdelkader, Mohamed
Agaccioglu, Hayrullah
Powiązania:
https://bibliotekanauki.pl/articles/28411608.pdf
Data publikacji:
2023
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
evaporation
lake water level
precipitation
stochastic time series models
water transfer
Opis:
Beyşehir Lake is the largest freshwater lake in the Mediterranean region of Turkey that is used for drinking and irrigation purposes. The aim of this paper is to examine the potential for data-driven methods to predict long-term lake levels. The surface water level variability was forecast using conventional machine learning models, including autoregressive moving average (ARMA), autoregressive integrated moving average (ARIMA), and seasonal autoregressive integrated moving average (SARIMA). Based on the monthly water levels of Beyşehir Lake from 1992 to 2016, future water levels were predicted up to 24 months in advance. Water level predictions were obtained using conventional time series stochastic models, including autoregressive moving average, autoregressive integrated moving average, and seasonal autoregressive integrated moving average. Using historical records from the same period, prediction models for precipitation and evaporation were also developed. In order to assess the model’s accuracy, statistical performance metrics were applied. The results indicated that the seasonal autoregressive integrated moving average model outperformed all other models for lake level, precipitation, and evaporation prediction. The obtained results suggested the importance of incorporating the seasonality component for climate predictions in the region. The findings of this study demonstrated that simple stochastic models are effective in predicting the temporal evolution of hydrometeorological variables and fluctuations in lake water levels.
Źródło:
Journal of Water and Land Development; 2023, 58; 158--170
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bayesian modelling for semi-competing risks data in the presence of censoring
Autorzy:
Bhattacharjee, Atanu
Dey, Rajashree
Powiązania:
https://bibliotekanauki.pl/articles/20312017.pdf
Data publikacji:
2023-06-13
Wydawca:
Główny Urząd Statystyczny
Tematy:
censoring
illness-death models
accelerated failure time model
Bayesian Survival Analysis
semi-competing risks
Opis:
In biomedical research, challenges to working with multiple events are often observed while dealing with time-to-event data. Studies on prolonged survival duration are prone to having numerous possibilities. In studies on prolonged survival, patients might die of other causes. Sometimes in the survival studies, patients experienced some events (e.g. cancer relapse) before dying within the study period. In this context, the semi-competing risks framework was found useful. Similarly, the prolonged duration of follow-up studies is also affected by censored observation, especially interval censoring, and right censoring. Some conventional approaches work with time-to-event data, like the Cox-proportional hazard model. However, the accelerated failure time (AFT) model is more effective than the Cox model because it overcomes the proportionality hazard assumption. We also observed covariates impacting the time-to-event data measured as the categorical format. No established method currently exists for fitting an AFT model that incorporates categorical covariates, multiple events, and censored observations simultaneously. This work is dedicated to overcoming the existing challenges by the applications of R programming and data illustration. We arrived at a conclusion that the developed methods are suitable to run and easy to implement in R software. The selection of covariates in the AFT model can be evaluated using model selection criteria such as the Deviance Information Criteria (DIC) and Log-pseudo marginal likelihood (LPML). Various extensions of the AFT model, such as AFT-DPM and AFT-LN, have been demonstrated. The final model was selected based on minimum DIC values and larger LPML values.
Źródło:
Statistics in Transition new series; 2023, 24, 3; 201-211
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Discrete identification of continuous non-linear andnon-stationary dynamical systems that is insensitive to noise correlation and measurement outliers
Autorzy:
Kozłowski, Janusz
Kowalczuk, Zdzisław
Powiązania:
https://bibliotekanauki.pl/articles/27312014.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
instrumental variable
non-linear continuous-time models
optimization
supervisory systems
security systems
system identification
Opis:
The paper uses specific parameter estimation methods to identify the coefficients of continuous-time models represented by linear and non-linear ordinary differential equations. The necessary approximation of such systems in discrete time in the form of utility models is achieved by the use of properly tuned ‘integrating filters’ of the FIR type. The resulting discrete-time descriptions retain the original continuous parameterization and can be identified, for example, by the classical least squares procedure. Since in the presence of correlated noise, the estimated parameter values are burdened with an unavoidable systematic error (manifested by asymptotic bias of the estimates), in order to significantly improve the identification consistency, the method of instrumental variables is used here. In our research we use an estimation algorithm based on the least absolute values (LA) criterion of the least sum of absolute values, which is optimal in identifying linear and non-linear systems in the case of sporadic measurement errors. In the paper, we propose a procedure for determining the instrumental variable for a continuous model with non-linearity (related to the Wienerian system) in order to remove the evaluation bias, and a recursive sub-optimal version of the LA estmator. This algorithm is given in a simple (LA) version and in an instrumental variable version (IV-LA), which is robust to outliers, removes evaluation bias, and is suited to the task of identifying processes with non-linear dynamics (semi-Wienerian/NLID). In conclusion, the effectiveness of the proposed algorithmic solutions has been demonstrated by numerical simulations of the mechanical system, which is an essential part of the suspension system of a wheeled vehicle.
Źródło:
Archives of Control Sciences; 2023, 33, 2; 391--411
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generative modelling of vibration signals in machine maintenance
Autorzy:
Puchalski, Andrzej Adam
Komorska, Iwona
Powiązania:
https://bibliotekanauki.pl/articles/28086927.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
time-frequency analysis
condition monitoring
anomalies detection
deep generative models
variational autoencoder
data distribution
Opis:
The exponential development of technologies for the acquisition, collection, and processing of data from real-world objects is creating new perspectives in the field of machine maintenance. The Industrial Internet of Things is the source of a huge collection of measurement data. The performance of classification or regression algorithms needs to take into account the random nature of the process being modelled and any incomplete observability, especially in terms of failure states. The article highlights the practical possibilities of using generative artificial intelligence and deep machine learning systems to create synthetic measurement observations in monitoring the vibrations of rotating machinery to improve unbalanced databases. Variational AutoencoderVAE generative models with latent variables in the form of high-level input features of time-frequency spectra were studied. The mapping and generation algorithm was optimised and its effectiveness was tested in the practical solution of the task of diagnosing the three operating states of a demonstration gearbox.
Źródło:
Eksploatacja i Niezawodność; 2023, 25, 4; art. no. 173488
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time series analysis in environmental epidemiology: challenges and considerations
Autorzy:
Gudziunaite, Sandra
Shabani, Zana
Weitensfelder, Lisbeth
Moshammer, Hanns
Powiązania:
https://bibliotekanauki.pl/articles/23364734.pdf
Data publikacji:
2023-12-15
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
statistical methods
regression models
environmental epidemiology
short-term effects
time series analyses
confounder control
Opis:
In environmental epidemiology, time series analyses represent a widely used statistical tool. However, though being commonly used, there is soften confusion regarding the specific requirements, such as which link function might be most appropriate, when or how to control for seasonality or how to account for lags. The present overview draws from experiences in other disciplines and discusses the proper execution of time series analyses based on considerations that are relevant in environmental epidemiology. Time series analysis in environmental epidemiology focuses on acute events caused by short-term changes in exposure. These exposures should be fairly wide-spread affecting a large number of persons, usually all inhabitants of a political entity. Pollutants in air or drinking water as well as meteorological factors serve as typical examples. Despite the many time series analyses performed world-wide, some health effects that would lend themselves to that approach are still under-explored. This would include also some neurological and psychiatric endpoints.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2023, 36, 6; 704-716
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of a near wall model to Navier-Stokes equations with nonlinear time-relaxation model
Autorzy:
İhan, Özgül
Powiązania:
https://bibliotekanauki.pl/articles/2175530.pdf
Data publikacji:
2022
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
boundary layers
laminar
near wall models
NWM
Navier-Stokes equation with nonlinear time-relaxation model
NSE-NTR
warstwy graniczne
równanie Naviera-Stokesa z nieliniowym modelem relaksacji w czasie
Opis:
It is difficult and essential to determine appropriate boundary conditions for the flow averages because they depend on the behavior of the unknown flow near the wall. Large-eddy simulation (LES) is one of the promising approaches. LES estimates local spatial averages ū of the velocity u of the fluid. The main problem is modeling near-wall turbulence in complex geometries. Inspired by the works of Navier and Maxwell, the boundary conditions are developed on the wall. In this study, the appropriate friction coefficient for 2-D laminar flows is computed, and existing boundary layer theories are used to improve numerical boundary conditions for flow averages. The slip with friction and penetration with resistance boundary conditions are considered. Numerical tests on two-dimensional channel flow across a step using this boundary condition on the top and bottom wall and the step are performed.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2022, 21, 2; 39--50
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Forecasting Models Based on Fuzzy Logic: An Application on International Coffee Prices
Modele prognostyczne oparte na logice rozmytej: aplikacja dotycząca międzynarodowych cen kawy
Autorzy:
Fatih, Chellai
Powiązania:
https://bibliotekanauki.pl/articles/2168712.pdf
Data publikacji:
2022
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
fuzzy logic
time series
forecasting
coffee prices
FTS models
logika rozmyta
szeregi czasowe
prognozowanie
ceny kawy
Opis:
In recent decades, Fuzzy Time Series (FTS) has become a competitive, sometimes complementary, approach to classical time series methods such as that of Box-Jenkins. This study has two different purposes: a theoretical purpose, presenting an overview of the fuzzy logic and fuzzy time series models, and a practical purpose, which is to estimate and forecast monthly international coffee prices during the period 2000-2022. Analysing and forecasting the dynamics of coffee prices is of great interest to producers, consumers, and other market actors in managing and making rational decisions. The findings showed that international coffee prices exhibited significant fluctuations, with large increases and decreases influenced mainly by the level of top-ranked producers. The forecasted results revealed that a decrease in prices during the next six months (Jan 2023 to June 2023) is expected. Based on the results, it is also clear that the FTS models are more flexible and can be applied in forecasting time-series variables. At the same time, volatility and, sometimes, the unexpected swingsin coffee prices continue to draw more criticism and raise different issues regarding the roles of the markets and countries in ensuring food security.
W ostatnich dziesięcioleciach rozmyte szeregi czasowe stały się konkurencyjnym, czasem uzupełniającym, podejściem wobec klasycznych metod analizy szeregów czasowych, takich jak metoda Boxa-Jenkinsa. Prezentowane badanie ma dwa różne cele: cel teoretyczny, w którym przedstawiono przegląd logiki rozmytej i modeli rozmytych szeregów czasowych, oraz cel praktyczny, którym jest oszacowanie i prognoza miesięcznych międzynarodowych cen kawy w okresie 2000-2022. Analiza i prognozowanie dynamiki cen kawy ma duże znaczenie dla producentów, konsumentów i uczestników rynku w zarządzaniu i podejmowaniu racjonalnych decyzji. Wyniki pokazały, że międzynarodowe ceny kawy wykazywały duże wahania, z dużymi wzrostami i spadkami, na które wpływ miał głównie poziom czołowych producentów. Zgodnie z wynikami prognoz należy spodziewać się spadku cen w ciągu najbliższych sześciu miesięcy (od stycznia do czerwca 2023 r.). Na podstawie uzyskanych wyników można stwierdzić, że modele FTS są bardziej elastyczne i mogą być stosowane w prognozowaniu zmiennych szeregów czasowych. Z drugiej strony zmienność, a czasami nieoczekiwane zmiany cen kawy nadal powodują coraz większą krytykę i sygnalizują, że należy zwrócić uwagę na różne kwestie dotyczące roli rynków i państw w zapewnianiu bezpieczeństwa żywnościowego.
Źródło:
Econometrics. Ekonometria. Advances in Applied Data Analytics; 2022, 26, 4; 1-16
1507-3866
Pojawia się w:
Econometrics. Ekonometria. Advances in Applied Data Analytics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Forecasting municipal waste accumulation rate and personal consumption expenditures using vector autoregressive (VAR) model
Autorzy:
Bień, Jurand
Powiązania:
https://bibliotekanauki.pl/articles/23966648.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Menedżerów Jakości i Produkcji
Tematy:
wskaźnik akumulacji odpadów
wydatki konsumpcyjne
prognozowanie
analiza szeregów czasowych
wielowymiarowe szeregi czasowe
model autoregresji wektorowej
waste accumulation rate
consumption expenditures
forecasting
time-series analysis
multivariate time series models
vector autoregression model
Opis:
Accurate forecasting of municipal solid waste (MSW) generation is important for the planning, operation and optimization of municipal waste management system. However, it’s not easy task due to dynamic changes in waste volume, its composition or unpredictable factors. Initially, mainly conventional and descriptive statistical models of waste generation forecasting with demographic and socioeconomic factors were used. Methods based on machine learning or artificial intelligence have been widely used in municipal waste projection for several years. This study investigates the trend of municipal waste accumulation rate and its relation to personal consumption expenditures based on the yearly data achieved from Local Data Bank (LDB) driven by Polish Statistical Office. The effect of personal consumption expenditures on the municipal waste accumulation rate was analysed by using the vector autoregressive model (VAR). The results showed that such method can be successfully used for this purpose with an approximate level of 2.3% Root Mean Square Error (RMSE).
Źródło:
Production Engineering Archives; 2022, 28, 2; 150--156
2353-5156
2353-7779
Pojawia się w:
Production Engineering Archives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
State-dependent Autoregressive Models with p Lags: Properties, Estimation and Forecasting
Autorzy:
Gobbi, Fabio
Mulinacci, Sabrina
Powiązania:
https://bibliotekanauki.pl/articles/2119921.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
convolution-based autoregressive models
level-increment dependence
nonlinear time series
maximum likelihood
forecasting accuracy
Opis:
In this paper we consider a class of nonlinear autoregressive models in which a specific type of dependence structure between the error term and the lagged values of the state variable is assumed. We show that there exists an equivalent representation given by a p-th order state-dependent autoregressive (SDAR(p)) model where the error term is independent of the last p lagged values of the state variable (yt−1, . . . , yt−p) and the autoregressive coefficients are specific functions of them. We discuss a quasi-maximum likelihood estimator of the model parameters and we prove its consistency and asymptotic normality. To test the forecasting ability of the SDAR(p) model, we propose an empirical application to the quarterly Japan GDP growth rate which is a time series characterized by a level-increment dependence. A comparative analyses is conducted taking into consideration some alternative and competitive models for nonlinear time series such as SETAR and AR-GARCH models.
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2022, 1; 81-108
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Formulas for average transition times between states of the Markov birth-death process
Autorzy:
Zhernovyi, Yuriy
Kopytko, Bohdan
Powiązania:
https://bibliotekanauki.pl/articles/2175497.pdf
Data publikacji:
2021
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
birth-death process
Markov models
mean transition time
mean time spent in the group of states
queueing systems
reliability model
proces narodzin i śmierci
modele Markova
średni czas przejścia
średni czas spędzony w grupie stanów
systemy kolejkowe
model niezawodności
Opis:
In this paper, we consider Markov birth-death processes with constant intensities of transitions between neighboring states that have an ergodic property. Using the exponential distributions properties, we obtain formulas for the mean time of transition from the state i to the state j and transitions back, from the state j to the state i. We found expressions for the mean time spent outside the given state i, the mean time spent in the group of states (0,...,i-1) to the left from state i, and the mean time spent in the group of states (i+1,i+2,...) to the right. We derive the formulas for some special cases of the Markov birth-death processes, namely, for the Erlang loss system, the queueing systems with finite and with infinite waiting room and the reliability model for a recoverable system.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2021, 20, 4; 99--110
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Markov reliability models of series systems with redundancy and repair facilities
Autorzy:
Zhernovyi, Yuriy
Kopytko, Bohdan
Powiązania:
https://bibliotekanauki.pl/articles/2141508.pdf
Data publikacji:
2021
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
reliability
recoverable system
redundancy
series system
Markov models
mean time to failure
mean time between failures
mean downtime
niezawodność
redundancja
modele Markova
średni czas bezawaryjnej pracy
średni czas pomiędzy uszkodzeniami
Opis:
In this paper, we use Markov models for studying the reliability of series systems with redundancy and repair facilities. We suppose that the units’ time to failure and recovery times are exponentially distributed. We consider the cases when 1≤ c ≤ m and m + 1 ≤ c ≤ m + n, for the system of n operating units, m unloaded redundant units and c repair facilities. Using the exponential distributions properties, we obtain stationary reliability indices of the series systems: steady-state probabilities, a stationary availability coefficient, mean time to failure, mean time between failures and mean downtime.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2021, 20, 3; 89-96
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predicting the seasonality of passengers in railway transport based on time series for proper railway development
Autorzy:
Borucka, Anna
Guzanek, Patrycja
Powiązania:
https://bibliotekanauki.pl/articles/2098132.pdf
Data publikacji:
2021
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
rail transport
passenger flow
time series models
transport kolejowy
przepływ pasażerów
modele szeregów czasowych
Opis:
Planning the frequency of rail services is closely related to forecasting the number of passengers and is part of the comprehensive analysis of railway systems. Most of the research presented in the literature focuses only on selected areas of this system (e.g. urban agglomerations, urban underground transport, transfer nodes), without presenting a comprehensive evaluation that would provide full knowledge and diagnostics of this mode of transport (i.e. railway transport). Therefore, this article presents methods for modelling passenger flow in rail traffic at a national level (using the example of Poland). Time series models were used to forecast the number of passengers in rail transport. The error, trend, and seasonality (ETS) exponential smoothing model and the model belonging to the ARMA class were used. An adequate model was selected, allowing future values to be forecast. The autoregressive integrated moving average (ARIMA) model follows the tested series better than the ETS model and is characterised by the lowest values of forecast errors in relation to the test set. The forecast based on the ARIMA model is characterised by a better detection of the trends and seasonality of the series. The results of the present study are considered to form the basis for solving potential rail traffic problems, which depend on the volume of passenger traffic, at the central level. The methods presented can also be implemented in other systems with similar characteristics, which affects the usability of the presented solutions.
Źródło:
Transport Problems; 2021, 16, 1; 51--61
1896-0596
2300-861X
Pojawia się w:
Transport Problems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remuneration and working time of teachers in Poland ‒ compared to other European countries
Wynagrodzenie i czas pracy nauczycieli w Polsce ‒ na tle innych krajów europejskich
Autorzy:
Miko-Giedyk, Justyna
Powiązania:
https://bibliotekanauki.pl/articles/2040188.pdf
Data publikacji:
2021-11-04
Wydawca:
Uniwersytet Kazimierza Wielkiego w Bydgoszczy
Tematy:
wynagrodzenie nauczycieli
czas pracy nauczycieli
modele czasu pracy
teachers remuneration
teachers working time
working time models
Opis:
The paper discusses the remuneration and working time of Polish teachers in relation to other European countries. The basis for comparison is constituted by international reports and national documents, but they should not be construed without insight into definition differences and in isolation from national specifics. Purely statistical comparison without knowledge of the context may lead to erroneous conclusions. For example, when it comes to the presentation of teachers’ statutory working time, there are several models for defining it in European countries, and the direct ranking of countries defining working time in terms of obligatory teaching hours only (Poland, Austria, Belgium, Finland) next to countries (Denmark, Estonia, Malta) that use a definition of general working time may distort the actual situation.
W artykule omawiane są kwestie wynagrodzenia i czasu pracy polskich nauczycieli w odniesieniu do innych krajów europejskich. Bazą wyjściową do porównania są międzynarodowe raporty oraz dokumenty krajowe, jednak nie należy ich interpretować bez wniknięcia w różnice definicyjne i w oderwaniu od specyfiki państwowej. Komparacja czysto statystyczna bez znajomości kontekstu może prowadzić do wyciągnięcia błędnych wniosków. Na przykład, jeśli chodzi o przedstawianie ustawowego czasu pracy nauczycieli, w krajach europejskich istnieje kilka modeli go określających i bezpośrednie uszeregowanie państw, w których czas pracy definiuje się przez pryzmat tylko pensum dydaktycznego (Polska, Austria, Belgia, Finlandia), obok krajów (Dania, Estonia, Malta), gdzie określa się ogólny czas pracy, co może powodować zniekształcenie rzeczywistości.
Źródło:
Szkoła - Zawód - Praca; 2021, 21; 54-71
2082-6087
Pojawia się w:
Szkoła - Zawód - Praca
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Понятие «ВРЕМЯ» в нижнелужицком языке
The concept of TIME in the Lower Sorbian language
Autorzy:
Кондратенко, Михаил
Powiązania:
https://bibliotekanauki.pl/articles/1854352.pdf
Data publikacji:
2021-12-10
Wydawca:
Poznańskie Towarzystwo Przyjaciół Nauk
Tematy:
categories of time
Lower Sorbian language
dialectology
semantic models
категории времени
нижнелужицкий язык
диалектология
семантические модели
Opis:
Определение сущности времени в языковом его представлении включает множество аспектов, но для выявления и классификации качественных характеристик данного объекта номинации целесообразно рассматривать некоторые семантические модели, которые складываются вследствие опосредованных языком закономерностей интерпретации понятия ‘время’. Такими моделями являются манифестации этого понятия полисемичными лексемами, раскрывающими при переносе наименования специфический образ времени; выражение связи между прошлым, настоящим и будущим; мотивация наименований периодов времени разновидностями сельскохозяйственных и иных работ; репрезентация аксиологических характеристик.
There are many aspects of the definition of the nature of time in language but in identifying and classifying the characteristics of the object category, some of the semantic models prove useful. They result from indirect language patterns used to interpret the concept of ‘time’. These models are manifestations of this concept by polysemy lexemes, which reveal a specific image of time when transferring a notion; it is an expression of the connection between the past, present and future; motivation of notions of time periods by varied agricultural and other works; representation of axiological characteristics.
Źródło:
Gwary Dziś; 2021, 14; 175-182
1898-9276
Pojawia się w:
Gwary Dziś
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The fossil record of camelids demonstrates a late divergence between Bactrian camel and dromedary
Autorzy:
Geraads, D.
Didier, G.
Barr, W.A.
Reed, D.
Laurin, M.
Powiązania:
https://bibliotekanauki.pl/articles/2082155.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Mammalia
Camelidae
phylogeny
divergence time
fossil record
birth-and-death models
Pleistocene
Africa
Opis:
A new compilation of the Old World fossil record of Camelidae and a recent phylogenetic analysis allow a new assessment of the timing of the clade’s diversification. Using a recent implementation of the fossilized birth-death process, we show that the divergence between Bactrian camel and dromedary has a peak probability density around 1 Ma and probably occurred less than 2 million years ago. These dates are much younger than molecular estimates, which place the divergence between the dromedary and the Bactrian camel between 4 and 8 million years ago. Calibration problems in molecular dating seem to explain much of this difference.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 2; 251-260
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 58

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