جستجوی مقالات مرتبط با کلیدواژه « model » در نشریات گروه « برق »

In this paper, we propose a new model to describe variations in interpretation and perception of a simple sentence by different people. To show the understandability of a simple sentence in the prediction of future situations, the meaning of a sentence is modeled as a fuzzy if-then rule, and the fuzzy model is investigated in an iterative process. The main goal of the paper is modeling a linguistic rule. This is done using an if-then rule and its variation through one person to another. The model predicts that the interpretation reaching the final person in the following years can be chaotic and thus unpredictable.

Aiming at the problem of small sample modelling of oil price and exchange rate with time-delayed causality, a grey multivariate time lag model and its solution are proposed against the new economic background of economic development, structural optimization and power conversion. Considering the difficulty of solving q-order differential equations analytically, we obtain a numerical solution. On the basis of this solution, the validity of the model is proved. The numerical results show that the model can describe and predict the operating rules of oil price and exchange rate economic systems with time delay, and it is concluded that the development of oil price and exchange rate is not coordinated under the new state of the economy.  The relationship of oil prices and the exchange rate has changed in this state, oil prices have a positive effect on the rise of the exchange rate.

An important issue in power generation and petrochemical industries is monitoring pipe wall thickness and corrosion/erosion rate. In this thesis, a combination of signal processing techniques are used to estimate the corrosion rate estimates based on MBE. Corrosion rate is estimated based on ultrasonic pipe wall thickness data is collected over a short period of time using MBE model. This technique is based on data collected from the speedometer applied for thinning and both indicate that they were able to estimate the rate of corrosion in short periods of time and with good accuracy.

An adaptive process consists of dynamic elements, and management rules which govern their run-time behaviors. The WS-CDL describes collaborative business processes between service consumers and providers. Adapting the processes to runtime changes becomes a demanding challenge, because the WS-CDL has static technology-dependent structure, and does not support the separation of concerns. Here, we propose a model-driven approach to transform WS-CDL into UML state machine (behavioral and protocol models), and subsequently into implementation code. Besides separating the business logic from the implementation, the state machine has a dynamic structure which is verifiable and adaptable. As a result, we can easily modify the process flow or change the management rules at run-time, and reflect their effects on the running process instances. We present an ‘itinerary purchase’ case study for prototyping the transformation rules.

The purpose of this paper is to put forward the effect of different turbulence closer models on an enhanced Moving Particle Semi-implicit (MPS) method for solving continuity and momentum equations of viscous fluid. MPS method is a mesh- free Lagrangian method capable of solving non-linear governing equations and simulating complex free surface flow circumstances. Various turbulence closer models are added to a MPS program and applied it to different fluid mechanic problems to investigate the effect of these types of closure. Dam break simulation outcome indicates that two-equation turbulence model improves free surface estimation accuracy most. It also shows that type of utilized Kernel function has no significant efficacy on stability when the effect of turbulence is included. Further, an algorithm called Incomplete Conjugate Cholesky Gradient (ICCG) is applied for computing pressure implicitly. Applying developed model to well-known sample problems cited in the literature represents that using turbulence closure models can enhance the prediction of developed model as well as stability of the simulations.

In poorly developed fractured rocks, the contribution of individual fracture on rock conductivity should be considered. However, due to the lack of data, a deterministic approach cannot be used. The conventional way to model discrete fractures is to use a Poisson process, with prescribed distribution, for fracture size and orientation. Recently, a stochastic approach, based on the idea that the elastic energy due to fractures follows a Boltzmann distribution, has been used to generate realizations of correlated fractures in two dimensions. The elastic energy function has been derived by applying the appropriate physical laws in an elastic medium. The resulting energy function has been used in the simulated annealing algorithm to generate the realizations of two dimensional fracture networks. The main contribution of this work is to extend this technique to 3D, and to better incorporate geological field observations. In 3D, the method has adjusted the orientation of fractures to three orthogonal sets. Moreover, we investigate the effects of boundary condition, fracture size distribution, and the anisotropy of the medium. We have observed that far field stress can control the orientation of fractures. As a result, this fracture modeling technique can be used to stochastically generate sub-seismic fractures.

Phenomena related to the fatigue behavior of pavements are among the most important concerns confronting pavement designers. Damage caused by pavement fatigue requires large amounts of money to be budgeted for the maintenance and rehabilitation of highway and airport pavements, and this expenditure motivates research into methods to reduce the fatigue damage. One of these proposed solutions is the inclusion of waste materials in the material used for pavement construction to increase its strength against dynamic loading. Many models have been developed for predicting the fatigue behaviour of asphalt concrete pavements, but none exist for asphalt mixtures modified by the addition of waste materials. This paper presents the first model of the fatigue behaviour of glass-asphalt (glasphalt) mixtures, which is able to describe the fatigue behaviour of glasphalt under dynamic loading. The proposed model is then compared with a number of previously suggested models for the behaviour of Hot Mix Asphalt (HMA). Glasphalt concrete mixtures are shown to have a longer fatigue life than HMA.