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Two phase flow systems have been widely used in industrial engineering. Phase distribution characteristics are vital to the safety operation and optimization design of two phase flow systems. Lift force has been known as perpendicular to the bubbles’ moving direction, which is one of the mechanisms of interfacial momentum transfer. While most widely used lift force correlations, such as the correlation of Tomiyama et al. (2002), were obtained by experimentally tracking single bubble trajectories in high viscosity glycerol–water mixture, the applicability of these models into low viscosity fluid, such as water in nuclear engineering system, needs to be further evaluated. In the present paper, bubble in low viscosity fluid in shear flow was investigated in a full 3D numerical simulation and the volume of fluid (VOF) method was applied to capture the interface. The fluid parameter: fluid viscosity, bubble parameter: diameter and external flow parameters: shear stress magnitude and liquid velocity were examined. Comparing with bubble in high viscosity shear flow and bubble in low viscosity still flow, relative large bubble in low viscosity shear flow keep an oscillation way towards the moving wall and experienced a shape deformation process. The oscillation amplitude increased as the viscosity of fluid decreased. Small bubble migrated to the static wall in a line with larger migration velocity than that in high viscosity fluid and no deformation occurred. The shear stress triggered the oscillation behaviors while it had no direct influence with the behavior. The liquid velocity had no effect on lift coefficient in the present research range of 0 < V < 0.186 m/s.

A two-dimensional temporal and spatial correlated lognormal clutter sequence generation method based on FPGA is proposed. This method solves the problem of long generation time generating the sequence based on the DSP, due to the higher sampling rates or long data, which is difficult to meet real-time requirements of the data generated‥ In this paper, based on FPGA, using a one-dimensional temporal correlated Lognormal clutter sequence and one-dimensional Gaussian random sequence, using a single precision floating-point matrix multiplier and adders and multipliers of FPGA IP core, methods are proposed to generate two-dimensional temporal spatial correlated lognormal clutter sequence. One single precision floating-point matrix multiplier includes an input data buffer and output data buffer, a single-precision floating-point adder, a single-precision floating-point multiplier and data access control module. Two-dimensional temporal and spatial correlated lognormal clutter generated each step employs parallel processing method, the method avoids the problems of existing methods that instruction cycles execute serially and meet the requirements of real-time data generation.

Currently software defined radio (SDR) is implemented by using DSP only or by using DSP plus FPGA chip. For DSP processing speed of the bottleneck problem, a complete FPGA IF software radio implementation is proposed in this paper. Traditional solutions use only FPGA for digital up and down conversion, modulation and demodulation; design proposed in this paper based on the FPGA chip, a CPU processor for SDR is designed. By using this processor, the full realization of all digital signal processing algorithms on software radio is implemented by FGPA only. Because of the full use of FPGA to implement software radio, so that the system power consumption is smaller, to solve the needs of software radio for defined power. In this paper, based on the FPGA chip CPU design method, the proposed greatly reduces the difficulty of FPGA development; the use of C language and assembly language to develop digital signal processing on FPGA platform, greatly reducing system development time.

During severe accident in the nuclear power plant, a considerable amount of hydrogen can be generated by an active reaction of the fuel-cladding with steam within the pressure vessel which may be released into the containment of nuclear power plant. Hydrogen combustion may occur where there is sufficient oxygen, and the hydrogen release rates exceed 10% of the containment. During hydrogen combustion, detonation force and short term pressure may be produced. The production of these gas species can be detrimental to the structural integrity of the safety systems of the reactor and the containment. In 1979, the Three Mile Island (1979) accident occurred. This accident compelled experts and researchers to focus on the study of distribution of hydrogen inside the containment of nuclear power plant. However after the Fukushima Dai-ichi nuclear power plant accident (2011), the modeling of the gas behavior became important topic for scientists. For the stable and normal operation of the containment, it is essential to understand the behavior of hydrogen inside the containment of nuclear power plant in order to mitigate the occurrence of these types of accidents in the future. For this purpose, it is important to identify how burnable hydrogen clouds are produced in the containment of nuclear power plant. The combustion of hydrogen may occur in different modes based on geometrical complexity and gas composition. Reliable turbulence models must be used in order to obtain an accurate estimation of the concentration distribution as a function of time and other physical phenomena of the gas mixture. In this study, a small scale hydrogen-dispersion case is selected as a benchmark to address turbulence models. The computations are performed using HYDRAGON code developed by Department of Engineering Physics, Tsinghua University, China. HYDRAGON code is a three dimensional thermal-hydraulics analysis code. The purpose of this code is to predict the behavior of hydrogen gas and multiple gas species inside the containment of nuclear power plant during severe accident. This code mainly adopts CFD models and structural correlations used for wall flow resistance instead of using boundary layer at a wall. HYDROGAN code analyzes many processes such as hydrogen diffusion condensation, combustion, gas stratification, evaporation, mixing process. The main purpose of this research is to study the influence of turbulence models to the concentration distribution and to demonstrate the code thermal-hydraulic simulation capability during nuclear power plant accident. The calculated results of various turbulence models have different prediction values in different compartments. The results of k–ε turbulence model are in reasonable agreement as compared to the benchmark experimental data.

The paper presents the development of a sub-channel thermal-hydraulic analysis code named SUBCHAN. The code was originally developed to analyze super critical CANDU type reactor which has such characters as horizontal fuel channels, heavy water moderated, super critical light water cooled, any type of fuel bundle with or without thorium rods. Thermal-hydraulic model of SUBCHAN is based on four partial differential equations that describe the conservation of mass, energy and momentum vector in axial and lateral directions for the water liquid/vapor mixture. The heat transfer correlations and pressure drop correlations used in the SUBCHAN code are presented in this paper. The water properties package of the code is based on the Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam. The heat transfer correlation of super critical region is based on the experimental investigation of Xi'an Jiaotong University and Dyadyakin and Popov correlation. By calculating the TACR case, which is operating at 12.5 MPa pressure, compared with the results of ASSERT-PV code, the paper gets the conclusion that the development of the SUBCHAN code with super critical water property package is successful. Then the paper uses the SUBCHAN code to analyze CANDU-SCWR which is operating at 25.0 MPa pressure. The paper gets the conclusion that the SUBCHAN code can be used to analyze the steady state sub-channel thermal-hydraulic analysis of CANDU-SCWR fuel channel.

This paper presents a thorium fuel cycle scheme for the thorium-based advancednuclear energy system JANES). TANES that will use thorium resources is a homemade nuclear energy system that is fit for the situation of China and some other thorium-rich regions. By the reactor physics and fuel cycle analysis, the paper gets the conclusion that if TANES decreases lattice pitch (channel pitch) and increases driver fuel enrichment, TANES will provide a slightly negative coolant void reactivity coefficient to facilitate implementation of advanced automatic control technology.

This paper considers iterative detection and decoding on the concatenated communication channel consisting of a two-dimensional magnetic recording (TDMR) channel modeled by the four-grain rectangular discrete grain model (DGM) proposed by Kavcic et. al., followed by a two-dimensional intersymbol interference (2D-ISI) channel modeled by linear convolution of the DGM model's output with a finite-extent 2D blurring mask followed by addition of white Gaussian noise. An iterative detection and decoding scheme combines TDMR detection, 2D-ISI detection, and soft-in/soft-out (SISO) channel decoding in a structure with two iteration loops. In the first loop, the 2D-ISI channel detector exchanges log-likelihood ratios (LLRs) with the TDMR detector. In the second loop, the TDMR detector exchanges LLRs with a serially concatenated convolutional code (SCCC) decoder. Simulation results for the concatenated TDMR and 2 x 2 averaging mask ISI channel with 10 dB SNR show that densities of 0.48 user bits per grain and above can be achieved, corresponding to an areal density of about 9.6 Terabits per square inch, over the entire range of grain probabilities in the TDMR model., 8 pages, 11 figures, 1 table