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21.
22.
In this paper, we study optimal retirement in a two-dimensional incomplete market caused by borrowing constraints and forced unemployment risk. We show that the two aspects jointly affect an individual’s optimal consumption, investment, and retirement strategies. In contrast to the complete market case, the endogenously determined wealth threshold for retirement is significantly affected by the two-dimensional market incompleteness, resulting in a lower wealth threshold. We also discuss a possible unemployment insurance scheme for the borrowing-constrained individual to respond to the shocks of forced unemployment. 相似文献
23.
Roumen Anguelov Evgenija D. Popova 《Journal of Computational and Applied Mathematics》2010,235(2):358-365
This paper brings together two methods producing numerical solutions with a statement of their quality — the nonstandard finite difference method and the method of validated computing. It deals with the construction and the analysis of reliable numerical discretizations of dynamical systems by employing these two techniques. An epidemiological model is used as a model example for their combined application. 相似文献
24.
Jean-Pierre Planckaert El-Hadi Djermoune David Brie Francis Briand Frédéric Richard 《Applied Mathematical Modelling》2010
This paper investigates some issues in physical modeling of metal inert gas/metal active gas (MIG/MAG) welding process in the short arc mode. In this mode, a metal supply is molten in the arc state and then transferred to the weld pool during the short-circuit state. A hybrid model having two distinct continuous states whose switchings are controlled by two guard conditions is proposed. Due to the complexity of the physical phenomena involved in the welding process, simplifications are used to obtain a model accounting for the main physical contributions but simple enough to yield an efficient, fast and numerically tractable simulator which can be used intensively for evaluating different control strategies. In an attempt to validate the proposed model, different measurements have been made including supply voltage and current sampled synchronously with high speed digital video. In order to extract some relevant quantities representative of the metal transfer from image sequences, an active contour algorithm is developed and tested. The effectiveness of the proposed model in the prediction of major tendencies of a welding process, especially in the arc state, is shown using experimental data. Some limitations of the model during the metal transfer are also stressed and possible remedies are then proposed. 相似文献
25.
Simulation of dynamic speckle sequences and its application to the analysis of transient processes 总被引:2,自引:0,他引:2
A. Federico G.H. Kaufmann G.E. Galizzi H. Rabal M. Trivi R. Arizaga 《Optics Communications》2006,260(2):493-499
Dynamic speckle has been used in recent years to analyse several transient processes that are produced in industrial and biological applications. We present here a numerical simulation to generate a temporal sequence of dynamic speckle patterns which is based on a model used for speckle formation by the superposition of waves from discrete scattering centres. It is demonstrated that the first and second statistics of the intensity of each speckle image, the time history of the speckle pattern, the temporal evolution of the correlation coefficient, and the power spectral density of the intensity generated by the proposed model reproduce quite well those obtained from experimentally recorded data. The process of a fast drying paint is presented as an example of the application of the proposed numerical model. 相似文献
26.
A. Shabunin A. Efimov 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(3):387-393
A spatio-temporal process in the Lattice Lotka Volterra (LLV) model, when realized on low dimensional support, is studied.
It is shown that the introduction of a long-range mixing causes a drastic change in the system’s behavior, which transits
from small random-like fluctuations to global oscillations when the mixing rate transcends above a critical point. The amplitude
of the induced oscillations is well defined by the mixing rate and is insensitive to the initial conditions and the lattice
size variations. The observed behavior essentially differs from that predicted by the Mean-Field model which is conservative.
The oscillations are of limit-cycle type and appear as a stochastic analog of a Hopf bifurcation. 相似文献
27.
S.Y. Li B.W. Wang L. Weng Y. Zhou Y. Sun W.M. Huang 《Journal of magnetism and magnetic materials》2008
Based on the analysis of the magnetostriction for Terfenol-D composites, Terfenol-D 2-2 magnetostrictive composites have been prepared with laminations perpendicular to [1 1 2] axes. Then one of the samples was annealed in the vacuum at 423 K for 15 min at the magnetic field of 240 kA/m, which is along the direction of laminations and vertical to the [1 1 2] axes of the specimen. The static magnetostriction λ and dynamic magnetostrictive coefficient d33 of samples were measured under the compressive stress of 0, 2, 4, 6 and 8 MPa. Effects of the compressive stress and the magnetic field heat treatment on the magnetostriction λ have been investigated. It is found that the magnetostriction of 2-2 composites can be improved under the compressive stress when the magnetic field is larger than 20 kA/m. The magnetostriction of 2-2 composites with the magnetic field heat treatment increases under compressive stress, and it can reach 1390×10−6 at the magnetic field of 200 kA/m and under the compressive stress of 4 MPa, much larger than the value of 860×10−6 without the magnetic field heat treatment. The highest magnetostriction of the 2-2 composite with the magnetic field heat treatment can reach 1530×10−6. The dynamic magnetostrictive coefficient d33 of 2-2 composites with the magnetic field heat treatment have been improved, compared with that without magnetic field heat treatment. The maximum value of d33 of the sample with magnetic field heat treatment is 71% larger than that without magnetic field heat treatment. 相似文献
28.
Oussama Graja Bacem Zghal Kajetan Dziedziech Fakher Chaari Adam Jablonski Tomasz Barszcz Mohamed Haddar 《Comptes Rendus Mecanique》2019,347(1):49-61
Planetary gearboxes are widely used in industrial machines. They usually work in harsh environments giving rise to damages and high maintenance costs. Condition monitoring is a key action allowing one to detect the presence of such damage ensuring healthy running conditions. The knowledge of the dynamic behavior of such a gearbox can be achieved using modeling tools as a primary step before conditioning the monitoring subject. In addition, modeling a gear set can help in the stage of design in order to optimize physical and geometric parameters of the system. Therefore, in this work, a two-dimensional lumped parameter model is adopted to build all vibration sources. The time-varying mesh stiffness is approximated as a square wave form. A novel mathematical formulation is proposed to model the amplitude modulation phenomenon due to the rotational motion of the planets around the center of the gearbox. Finally, the overall vibration signal is concluded as a summation of all vibration components influenced by the modulation function. 相似文献
29.
Bin Yang Chen-Wu Liang Fei-Xue Lu Qin-Ting Chen Jin Chen 《Journal of Macromolecular Science: Physics》2019,58(2):341-354
The effects of bamboo flour (BF) content on the dynamic rheological properties of BF-filled HDPE composites were investigated. Our findings showed that the addition of BF caused an enhancement of the non-Newtonianism of wood-plastic composites (WPCs) melt as well as the appearance of some new relaxation processes. In addition, the viscosity and modulus of the BF-filled HDPE composites showed a remarkable increase at 170?°C and 190?°C when the BF content exceeded 30%, which could be associated with the solid-like property of the WPCs at high BF loading, we propose. The present study we suggest will be useful to the formula design as well as the optimization of processing parameters for WPCs in general. 相似文献
30.
《中国化学快报》2020,31(7):1919-1922
A novel BODIPY (boradiazaindacene) dye denoted as BODIPY-DT containing terpyridine unit has been designed and characterized. The dye is found to be selective and visual solvatochromic sensor toward DMF among test organic solvents. The sensing process displays time-controllable, dynamic signal outputs in the emission colors including red, purple, yellow and even white emission colors. It is presented that selective free radical oxidation reaction happens during the recognition process. 相似文献