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Deposition is found in many engineering processes, such as the asphaltene deposition in oil pipelines/wellbores, and biological and chemical foulings in pipes or heat exchangers. These deposition processes usually occur in a two-phase flow environment. This study develops a model for two-phase flow with deposition in vertical pipes. The model consists of three modules: Fluid Transport, Particle Transport,...
Asphaltene deposition in wellbores/pipelines causes serious production losses in the oil and gas industry. This work presents a numerical model to predict asphaltene deposition in wellbores/pipelines. This model consists of two modules: a Thermodynamic Module and a Transport Module. The Thermodynamic Module models asphaltene precipitation using the Peng-Robinson Equation of State with Peneloux volume...
Slot antennas on dielectric-coated perfectly conducting objects have extensively been studied by many investigators. For these problems, exact analytic solutions are available only for a limited number of geometries. These geometries include circular and elliptic cylinders, as well as, spheres and spheroids. Since these solutions maintain mathematical rigor, they provide not only exact solutions for...
Lattice Gas Automata (LGA) can be considered as an alternative to the conventional differential equation description of problems in electromagnetics. LGAs are discrete dynamical systems that are based on a microscopic model of the physics being simulated. The basic constituents of an LGA are discrete cells. These cells are interconnected according to certain symmetric requirements to form an extremely...
Lattice gas automata (LGA) are an alternative to the traditional differential equation based numerical methods now widely used in computational electromagnetics [1]. Lattice gas automata are based on studying the behaviour of an extremely large array of simple cells. The states of the cells are very simple, usually consisting of only a few bits per cell. A lattice gas is a microscopic description...
The study of wave mechanics in electromagnetism has traditionally been approached from a differential equation description of the physics. An alternative are Lattice Gas Automata, which arc discrete dynamical systems and are based on a microscopic model of the physics being simulated. A lattice gas automaton (LGA) is an extremely large regular lattice of simple interconnected cells where each cell...
Large signal modeling for the GaN devices are crucial for their applications. An improved large signal model for AlGaN/GaN HEMTs including comprehensive thermal effect is proposed in this work. To obtain accurate description of the thermal effect, the influence of the temperature on all the Angelov empirical model parameters like extrinsic resistance is studied. These parameters counting the thermal...
Spin-torque oscillator (STO) with reference layer (REF) has been proposed to be an efficient way to excite oscillation at low current density [1-2]. A well-controlled STO is the center part of microwave assisted magnetic recording (MAMR); however, in the recording process, the STO is exposed in an alternative external head field in addition to the applied current [3-4]. To assist the writing in MAMR,...
MAMR is one of the technologies which could push recording density up to 3–4 Tb/in2 [1-4]. The center part of MAMR is the spin torque oscillator (STO) for the generation of localized ac magnetic field in the microwave frequency regime of 20–30 GHz[5-6]. The STO is placed between the main pole and the trailing shield (Fig. 1a), where a strong magnetic field (gap field) exists. The gap field acts on...
The acceleration grid power supply (AGPS) is an important part of neutral beam injector (NBI) system. With the increasing of the NBI power, the requirement for output voltage of the AGPS is becoming higher and higher, even reaching to 1000 kV. As the Inverter type high voltage power supply uses the inverters located at lower voltage side to regulate and cut off the output voltage, it's very suitable...
In this paper, a novel learning-based fuzzy Linear Quadratic Regulator (LQR) control method using Extended Kalman Filter (EKF) to optimize a Mamdani fuzzy LQR controller is presented. The EKF is used to adjust the shape of membership functions and rules of the fuzzy controller to adapt with the working conditions automatically during the operation process to minimize the control error. Then, the LQR...
In this paper, we consider an inventory problem with random demand and random capacity in a fluctuating environment. Our objective is to minimize the total discounted cost during the whole sales horizon by choosing an appropriate replenishment policy. We show that the optimal ordering policy has an extended order-up-to type. The optimal cost function and the optimal ordering policy both have some...
Till 2015, a large scale, ultra-high voltage and AC/DC hybrid power transmission configuration, including three ??800 kV ultra-high voltage DC systems, will be formed. Eigenvalue and eigenvector of the system are calculated using the eigenvalue analysis method of multi-machine, information of oscillatory mode, such as damping ratio, correlation ratio, right-eigenvector and participation factor, are...
The problem of approximate optimal rejection to sinusoidal disturbances with zero steady-state error (ZSSE) for nonlinear systems is considered. Based on the internal model principle, a disturbance compensator is constructed through which the plant model with external disturbances is transformed into an augmented nonlinear system without disturbances. Introducing a sensitivity parameter and expanding...
In this paper, a low noise preamplifier used for a quartz-based gyro-meter is proposed. The preamplifier is based on charge amplifier. Unlike a traditional charge amplifier, which needs a high value of feedback resistance to stabilize its operation, the stability of the proposed preamplifier is ensured by resetting of the feedback capacitor periodically. As a result, the proposed preamplifier is simple...
The effects of initial glucose concentration and light intensity on specific growth rate, phycocyanin concentration and cell dry weight concentration in mixotrophic batch cultivation of Spirulina platensis using both shake flask and fermenter were investigated. Based on experimental results in shake flask culture, a number of mathematical models were constructed, and the optimal initial glucose concentration...
Lattice Gas Automata (LGA) can be considered as an alternative to the conventional differential equation description of problems in electromagnetics. LGAs are discrete dynamical systems that are based on a microscopic model of the physics being simulated. The basic constituents of an LGA are discrete cells. These cells are interconnected according to certain symmetric requirements to form an extremely...
Lattice gas automata (LGA) are an alternative to the traditional differential equation based numerical methods now widely used in computational electromagnetics[1]. Lattice gas automata are based on studying the behaviour of an extremely large array of simple cells. The states of the cells are very simple, usually consisting of only a few bits per cell. A lattice gas is a microscopic description of...
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