Context. Unlike gas-phase reactions, chemical reactions taking place on interstellar dust grain surfaces cannot always be modeled by rate equations. Due to the small grain sizes and low flux, these reactions may exhibit large fluctuations and thus require stochastic methods such as the moment equations. Aims. We evaluate the formation rates of H2, HD and D2 molecules on dust grain surfaces and ...

Uncertain delay differential equation is a type of differential equations driven by a canonical Liu process. This paper mainly focuses on the stability of uncertain delay differential equations. At first, the concept of stability in measure, stability in mean and stability in moment for uncertain delay differential equations will be presented. In addition, the sufficient condition for uncertain...

To establish more accurate equations for estimating the moment arm length and cross-sectional area of the erector spinae and rectus abdominis muscles, the effects of height, weight and age on those muscles were analyzed by using a high-order polynomial equation. Data on the moment arm length and cross-sectional area at L3/4 were obtained from MRI images of 152 males and 98 females. The statisti...

With Adaptively Weighted (AW) numerical integration, for a given set of quadrature 4 nodes, order and domain of integration, the quadrature weights are obtained by solving a system of 5 suitable moment fitting equations in least square sense. The moments in the moment equations 6 are approximated over a simplified domain that is homeomorphic to the original domain, and then 7 are corrected for ...

this study is an attempt to develop a model of the simultaneous structure of the aggregate dynamic supply and demand to be used for estimation of parameters from data related to iran’s economy. the method for developing the model is an application of the dynamic and simultaneous process of aggregate supply and demand. obtained differential equations are used for solve the model. to estimate the...

We derive a series of moment equations describing the motion and flavor transformation of neutrinos in supernova. We find a particular series of moments of neutrino density matrix in supernova. The emission angle distribution of neutrinos is described by this series of moments. We expand the equation of neutrinos using these moments and obtain moment equations. We find that these moments have v...

The objective of this paper is to seek an alternative to the numerical simulation of the Navier-Stokes equations by a method similar to solving the BGK-type modeled lattice Boltzmann equation. The proposed method is valid for both gas and liquid flows. A discrete flux scheme (DFS) is used to derive the governing equations for two distribution functions; one for mass and another for thermal ener...