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Tytuł:
Efficient computation of the MCTDHF approximation to the time-dependent Schrodinger equation
Autorzy:
Koch, O.
Powiązania:
https://bibliotekanauki.pl/articles/255895.pdf
Data publikacji:
2006
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
multi-configuration time-dependent Hartree-Fock method
time-dependent multi-particle Schrodinger equation
Coulomb potential
finite elements
Opis:
We discuss analytical and numerical properties of the multi-configuration time-dependent Hartree-Fock method for the approximate solution of the time-dependent multi-particle (electronic) Schrödinger equation which are relevant for an efficient implementation of this model reduction technique. Particularly, we focus on a discretization and Iow rank approximation in the evaluation of the meanfield terms occurring in the MCTDHF equations of motion, which is crucial for the computational tractability of the problem. We give error bounds for this approximation and demonstrate the achieved gain in performance.
Źródło:
Opuscula Mathematica; 2006, 26, 3; 483-497
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Existence and smoothing effects of the initial-boundary value problem for ∂u/∂t−Δσ(u) = 0 in time-dependent domains
Autorzy:
Nakao, Mitsuhiro
Powiązania:
https://bibliotekanauki.pl/articles/29519532.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
quasilinear parabolic equation
time-dependent domain
smoothing effect
Opis:
We show the existence, smoothing effects and decay properties of solutions to the initial-boundary value problem for a generalized porous medium type parabolic equations of the form $ u_t − Δσ(u) = 0 $ in $ Q(0, T) $ with the initial and boundary conditions $ u(0) = u0 $ and $ u(t)|_{∂Ω(t)} = 0 $, where Ω(t) is a bounded domain in $ R^N $ for each t ≥ 0 and $ Q(0,T) = \bigcup_{0<t<T} \Omega(t) \times {t}, T>0 $. Our class of $ σ(u) $ includes $ σ(u) = |u|^m u $, $ σ(u) = u log(1 + |u|^m), 0 ≤ m ≤ 2, $ and $ σ(u) |u|^m u// \sqrt{1+|u|^2} $, $ 1 ≤ m ≤ 2 $ etc. We derive precise estimates for $ ||u(t)||_{Ω(t),∞} $ and $ ||∇σ(u(t))||_{Ω(t),2}^2, t > 0 $, depending on $ ||u_0||_{Ω(0),r} $ and the movement of $ ∂Ω(t) $.
Źródło:
Opuscula Mathematica; 2023, 43, 5; 703-734
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical pulse splitting under temporal variations of reflecting medium
Autorzy:
Vorgul, I.Yu.
Marciniak, M.
Powiązania:
https://bibliotekanauki.pl/articles/308749.pdf
Data publikacji:
2000
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
optical pulse splitting
time dependent conductivity
reflecting boundary
Opis:
A possibility of light pulse transformation by transient reflecting medium is investigated theoretically. After solving 1D problem of such a reflection one estimates such a transformation in a plane optical waveguide with time-dependent conductivity of one of the reflected media. Three types of the conductivity time-dependences are considered: harmonic, Bessel-like and splash-like ones. Obtained results show a possibility of pulse splitting under an influence of time-harmonic conductivity and pulse collapse vy the other considered nonstationarities.
Źródło:
Journal of Telecommunications and Information Technology; 2000, 1-2; 66-70
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The predicting of the overall number of points in the Polish football leagueeague
Autorzy:
Brzyski, Damian
Powiązania:
https://bibliotekanauki.pl/articles/748762.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Football (soccer)
Statistical prediction
Time dependent model
Polish league
Opis:
In this paper we will discuss the issue of predicting the number of points gained at the end of the season by teams from the Polish football league. We will present and compare two models based on different approaches and show how their appropriate mixture improves the prediction accuracy. We shall use mean absolute error to measure a model's fit.
Źródło:
Mathematica Applicanda; 2013, 41, 1
1730-2668
2299-4009
Pojawia się w:
Mathematica Applicanda
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An EOQ model for deteriorating items with time-dependent exponential demand rate and penalty cost
Autorzy:
Kumar, Sushil
Powiązania:
https://bibliotekanauki.pl/articles/406387.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
inventory
deterioration
penalty cost
time-dependent exponential demand rate
Opis:
The present paper deals with an EOQ model for deteriorating items with time-dependent exponential demand rate and partial backlogging. Shortages are allowed and completely backlogged in this model. The backlogging rate of unsatisfied demand is assumed as a function of waiting time. The concept of penalty cost is introduced in the proposed model because there are many perishable products that do not deteriorate for some period of time and after that period they continuously deteriorate and lose their values. This loss can be incurred as penalty cost to the wholesalers/retailers. In any business organization, the penalty cost has an important role for special types of seasonal products and short life products. Therefore, the total cost of the product can be reduced by maximizing the demand rate and minimizing the penalty cost during a given period of time. The purpose of our study is to optimise the total variable inventory cost. A numerical example is also given to show the applicability of the developed model.
Źródło:
Operations Research and Decisions; 2019, 29, 3; 37-49
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of Channel Profit for Deteriorating Items when Trade Credit Linked to Order Quantity
Autorzy:
Sanas, Yogita
Kawale, Sunil
Lahji, Abdul Aziz
Powiązania:
https://bibliotekanauki.pl/articles/1177859.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Deterioration
Integrated Inventory Model
Order Quantity Dependent Trade Credit
Time Dependent Demand
Opis:
In this article, an attempt is made to optimize the joint total profit per unit time of vendor – buyer supply chain system where vendor offers different trade credit depends on order quantity to the buyer. Here items in the inventory are deteriorates with constant rate and demand is a linear function of time. Vendor is establishing threshold for allowing trade credit comprehensively to ensure the greatest benefit for both players. By analyzing total channel profit function, we developed the optimal solution to provide buyer’s order quantity and replenishment time. Numerical examples and sensitivity analysis are given to illustrate the theoretical results, and some managerial insights are also obtained.
Źródło:
World Scientific News; 2018, 98; 100-114
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frictional heating with time-dependent specific power of friction
Autorzy:
Topczewska, K.
Powiązania:
https://bibliotekanauki.pl/articles/386356.pdf
Data publikacji:
2017
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
brake disc
frictional heating
temperature
time-dependent power of friction
Opis:
In this paper analytical solutions of the thermal problems of friction were received. The appropriate boundary-value problems of heat conduction were formulated and solved for a homogeneous semi–space (a brake disc) heated on its free surface by frictional heat fluxes with different and time-dependent intensities. Solutions were obtained in dimensionless form using Duhamel's theorem. Based on received solutions, evolution and spatial distribution of the dimensionless temperature were analyzed using numerical methods. The numerical results allowed to determine influence of the time distribution of friction power on the spatio-temporal temperature distribution in brake disc.
Źródło:
Acta Mechanica et Automatica; 2017, 11, 2; 111-115
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal stresses due to frictional heating with time-dependent specific power of friction
Autorzy:
Topczewska, K.
Powiązania:
https://bibliotekanauki.pl/articles/386412.pdf
Data publikacji:
2017
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
frictional heating
temperature
thermal stresses
time-dependent power of friction
Opis:
In this paper influence of temporal profile of the specific friction power (i.e. the product of the coefficient of friction, sliding velocity and contact pressure) on thermal stresses in a friction element during braking was investigated. Spatio-temporal distributions of thermal stresses were analytically determined for a subsurface layer of the friction element, based on the model of thermal bending of a thick plate with unfixed edges (Timoshenko and Goodier, 1970). To conduct calculations, the fields of dimensionless temperature were used. These fields were received in the article (Topczewska, 2017) as solutions to a one-dimensional boundary-value problem of heat conduction for a semi-space heated on its outer surface by fictional heat flux with three, different time profiles of the friction power.
Źródło:
Acta Mechanica et Automatica; 2017, 11, 4; 280-284
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of the Moulding Process of Bentonite-Bonded Green Sand
Autorzy:
Abdulamer, D.
Kaduaw, A.
Powiązania:
https://bibliotekanauki.pl/articles/1837740.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
green sand mould
moulding processes
COMSOL multiphysics
time-dependent study
Opis:
Finite Element Method FEM via commercially available software has been used for numerical simulation of the compaction process of bentonite-bonded sand mould. The mathematical model of soil plasticity which involved Drucker-Prager model match with Mohr Coulomb model was selected. The individual parameters which required for the simulation process were determined through direct shear test based on the variation of sand compactability. The novelty of this research work is that the individual micro-mechanical parameters were adopted depend on its directly proportional to the change of sand density during the compaction process. Boundary conditions of the applied load, roller and fixed constraint were specified. An extremely coarse mesh was used and the solution by time-dependent study was done for investigation of material-dependent behaviour of green sand during the compaction process. The research implemented also simulation of the desired points in sand mould to predict behaviour of moulding process, and prevent failure of the sand mould. Distance dependent displacement and distance-dependent pressure have been determined to investigate the effective moulding parameters without spent further energy and cost for obtaining green sand mould. The obtained numerical results of the sand displacement show good agreement with the practical results.
Źródło:
Archives of Foundry Engineering; 2021, 21, 1; 67-73
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of the Moulding Process of Bentonite-Bonded Green Sand
Autorzy:
Abdulamer, D.
Kaduaw, A.
Powiązania:
https://bibliotekanauki.pl/articles/1837861.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
green sand mould
moulding processes
COMSOL multiphysics
time-dependent study
Opis:
Finite Element Method FEM via commercially available software has been used for numerical simulation of the compaction process of bentonite-bonded sand mould. The mathematical model of soil plasticity which involved Drucker-Prager model match with Mohr Coulomb model was selected. The individual parameters which required for the simulation process were determined through direct shear test based on the variation of sand compactability. The novelty of this research work is that the individual micro-mechanical parameters were adopted depend on its directly proportional to the change of sand density during the compaction process. Boundary conditions of the applied load, roller and fixed constraint were specified. An extremely coarse mesh was used and the solution by time-dependent study was done for investigation of material-dependent behaviour of green sand during the compaction process. The research implemented also simulation of the desired points in sand mould to predict behaviour of moulding process, and prevent failure of the sand mould. Distance dependent displacement and distance-dependent pressure have been determined to investigate the effective moulding parameters without spent further energy and cost for obtaining green sand mould. The obtained numerical results of the sand displacement show good agreement with the practical results.
Źródło:
Archives of Foundry Engineering; 2021, 21, 1; 67-73
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bi-objective routing in a dynamic network: An application to maritime logistics
Autorzy:
Maskooki, Alaleh
Nikulin, Yury
Powiązania:
https://bibliotekanauki.pl/articles/2050033.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
travelling salesman
time dependent network
multi-objective optimization
integer programming
Opis:
A bi-objectiveMILP model for optimal routing in a dynamic network with moving targets (nodes) is developed, where all targets are not necessarily visited. Hence, our problem extends the moving target travelling salesman problem. The two objectives aim at finding the sequence of targets visited in a given time horizon by minimizing the total travel distance and maximizing the number of targets visited. Due to a huge number of binary variables, such a problem often becomes intractable in the real life cases. To reduce the computational burden, we introduce a measure of traffic density, based on which we propose a time horizon splitting heuristics. In a real-world case study of greenhouse gas emissions control, using Automatic Identification System data related to the locations of ships navigating in the Gulf of Finland, we evaluate the performance of the proposed method. Different splitting scenarios are analysed numerically. Even in the cases of a moderate scale, the results show that near-efficient values for the two objectives can be obtained by our splitting approach with a drastic decrease in computational time compared to the exact MILP method. A linear value function is introduced to compare the Pareto solutions obtained by different splitting scenarios. Given our results, we expect that the present study is valuable in logistic applications, specifically maritime management services and autonomous navigation.
Źródło:
Control and Cybernetics; 2020, 49, 2; 211--232
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimating the probability of leaving unemployment for older people in Poland using survival models with censored data
Autorzy:
Grzenda, Wioletta
Powiązania:
https://bibliotekanauki.pl/articles/20311945.pdf
Data publikacji:
2023-06-13
Wydawca:
Główny Urząd Statystyczny
Tematy:
employment
older workers
proportional hazard model
time-dependent ROC curve
Opis:
Current demographic changes require greater participation of people aged 50 or older in the labour market. Previous research shows that the chances of returning to employment decrease with the length of the unemployment period. In the case of older people who have not reached the statutory retirement age, these chances also depend on the time they have left to retirement. Our study aims to assess the probability of leaving unemployment for people aged 50-71 based on their characteristics and the length of the unemployment period. We use data from the Labour Force Survey for 2019–2020. The key factors determining employment status are identified using the proportional hazard model. We take these factors into account and use the direct adjusted survival curve to show how the probability of returning to work in Poland changes as people age. Due to the fact that not many people take up employment around their retirement age, an in-depth evaluation of the accuracy of predictions obtained via the models is crucial to assess the results. Hence, in this paper, a time-dependent ROC curve is used. Our results indicate that the key factor that influences the return to work after an unemployment period in the case of older people in Poland is whether they reached the age of 60. Other factors that proved important in this context are the sex and the education level of older people.
Źródło:
Statistics in Transition new series; 2023, 24, 3; 241-256
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of signal of X4 unmanned aerial vehicle
Autorzy:
Mięsikowska, M.
Nowakowski, M.
Lorenc, W.
Chodnicki, M.
Powiązania:
https://bibliotekanauki.pl/articles/244241.pdf
Data publikacji:
2016
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
unmanned aerial vehicles
drones
time-dependent frequency analysis
signal analysis
Opis:
Unmanned aerial vehicles are increasingly used in military service and in everyday life. Drones can be used for many purposes i.e. recreation, military applications or to increase the safety of citizens. Unmanned aerial vehicle can become a source of information, based on which object/operator can make a certain decisions. Unmanned aerial vehicles are increasingly used in ecological research. UAV can be capable of making sophisticated maps and may scan terrain for forest fires. They can contribute to safe infrastructure maintenance and management. Often, however, these objects being in the possession of civilians can become a source of danger and impact on privacy. It is therefore necessary to detect and recognize such objects in a real time. The aim of this study was to analyse the acoustic signal of unmanned aerial vehicle equipped with four rotating propellers – X4 structure (12000 rpm/min). The maximum speed of the object is 60 km/h and the ceiling to which it can operate flights reaches 1500 m AGL. The acoustic signal was acquired by Olympus LS11 digital recorder. Recordings were performed when the object is away from the recording equipment at the distance of 1 km. Analysis of the recorded signal can provide a significant information about the unmanned aerial vehicle. Results showed that some specific characteristic signal features are clearly visible in the signal even if the object is far away from the recording equipment.
Źródło:
Journal of KONES; 2016, 23, 3; 321-326
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On one-dimensional diffusion processes living in a bounded space interval
Autorzy:
Milian, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1312065.pdf
Data publikacji:
1992
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
one-dimensional Itô equation
bounded strong solutions
time-dependent boundaries
Opis:
We prove that under some assumptions a one-dimensional Itô equation has a strong solution concentrated on a finite spatial interval, and the pathwise uniqueness holds.
Źródło:
Annales Polonici Mathematici; 1992, 57, 1; 13-19
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-dependent thermo-elastic creep analysis of thick-walled spherical pressure vessels made of functionally graded materials
Autorzy:
Kashkoli, M. D.
Nejad, M. Z.
Powiązania:
https://bibliotekanauki.pl/articles/949351.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
spherical pressure vessels
creep
time-dependent
thermoelastic
functionally graded material
Opis:
Assuming that the thermo-elastic creep response of the material is governed by Norton’s law and material properties, except Poisson’s ratio, are considered as a function of the radius of the spherical vessel, an analytical solution is presented for calculation of stresses and displacements of axisymmetric thick-walled spherical pressure vessels made of functionally graded materials. This analytical solution could be used to study the time and temperature dependence of stresses in spherical vessels made of functionally graded materials. Creep stresses and displacements are plotted against dimensionless radius and time for different values of the powers of the material properties.
Źródło:
Journal of Theoretical and Applied Mechanics; 2015, 53, 4; 1053-1065
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 40

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