Development of 3-D Neutronic Kinetic Model and Control for CANDU Reactors

The development of a three dimensional (3-D) neutronic kinetic modeling process aiming at control system design for CANadian Deuterium Uranium (CANDU) reactors is carried out in this thesis using a modal synthesis method. In this method, the reactor space-time neutron flux is synthesized by a time-weighted series of precalculated neutron flux modes. These modes are eigenfunctions of the governing neutron diffusion equation at reference steady-state operating conditions. The xenon effect has also been considered. A special attention has been paid to compare the performance of the developed 3-D model with that of a traditional coupled point kinetic model. The 3-D reactor model is implemented by MATLAB/SIMULINK software environment. A nondimensionalized SIMULINK representation of the reactor model is established. The performance of the developed 3-D reactor neutronic kinetic model is then evaluated in a closed-loop environment with the help of a CANDU reactor regulating system (RRS) simulation platform. The dynamic behavior of the reactor model in a practical load-following mode has also been examined. The accuracy of the model has been validated against actual plant measurements under transient conditions. Through the analysis and simulation studies, it has convincingly demonstrated that the developed 3-D reactor model has significant advantages over the traditional coupled point kinetic model in terms of the improved accuracy and the higher resolution in modeling the reactor internal flux behaviors. Furthermore, using Graphic User Interface (GUI) techniques a user-friendly software package for the RRS simulation platform is developed. Based on the 3-D reactor model and identified deficiencies of existing RRS’ functions, an advanced 3-D reactor power distribution control is proposed and investigated. Linearization of the reactor model is performed and the performance of the linearized reactor model is evaluated in a closed-loop RRS environment. Using the feedback control law, a newly designed control strategy tries to suppress the effects of high order neutron flux modes and to emphasize behaviors of the dominant mode – the fundamental flux distribution adopted by the nominal design. Thereby, the 3-D power distribution shape during transients is optimally maintained closer to the nominal design shape than by the traditional RRS. The benefits of 3-D power distribution include not only the improved economical operation, but also improved safety as the uncertainties and the uneven power distribution are reduced. These have been confirmed by extensive simulation studies to Regional Overpower Protection (ROP) detectors’ flux transients during load following processes

Integrated CdTe PV glazing into windows: energy and daylight performance for different window-to-wall ratio

When integrated photovoltaics into building windows, the solar cells will absorb a fraction of solar radiation that hit on the window surface to generate electrical power and thus obstruct the solar energy and natural daylight that would have penetrated into inside space. In this paper, a window system integrated with thin film CdTe solar cells with 10% transparency was electrically characterised by Sandia model. The annual energy performance of a typical office with this PV window applied to different façade design was investigated using EnergyPlus under five typical climatic conditions in China. The dynamic daylight performance of the office has been assessed using RADIANCE. The result shows that when compared to a conventional double glazed system, the application of PV window can result in significant energy saving potential if the office has a relative large window-to-wall ratio (i.e. WWR≥45%). The simulation results also show that this PV window offers better daylight performance than conventional double-glazing

The Method of Realizing IPLL with Software

The concept of Phase-locked loop is earliest described in the 1820’s. In the late 1970 s, the theory of phase locked loop was given good description, but because of the difficulty of hardware implementation of a phase-locked loop, phase-locked loop, until a long time, was not widely used. In the 1970’s, with the rapidly development of integrated circuit (IC), PLL was widely used in modern communication system. Since then, the phase-locked loop had made great progress, and it was transferred from the earlier only used in field of high precision equipment to the all kinds of electronic products used in the consumer. Due to the rapid development of power system, power system signal analysis is more and more important. In this paper, according to the characteristics of the virtual radio technology and the basic principle of phase-locked loop to build software phase-locked loop, through the analysis of the improved phase-locked loop (IPLL), designed IPLL by way of the software. In this paper, based on the MATLAB simulation, the above analysis shows that the software phase-locked loop can be extracted grid signal, frequency, amplitude and phase of fundamental wave information for demand

Experimental study on simultaneously measuring Young\u27s modulus and internal fraction using self-mixing system

Material parameters such as Young\u27s modulus and internal friction are important for estimation of material performance. This paper presents an experimental study for measuring material related parameters using a selfmixing interferometric (SMI) configuration. An SMI system consists of a laser diode (LD), a lens and an external target to be measured. When a part of the lasing light back-reflected or back-scattered by the external target re-enters the LD internal cavity, both optical frequency and intensity of the lasing light can be modulated. This modulated laser intensity is often referred as SMI signal. Generally, the target related movement or its surface information can be retrieved from this SMI signal. In this paper, an SMI system is implemented. A tested sample is used as the target to form the external cavity of the LD. The tested sample is stimulated in vibration. Continuous wavelet transform (CWT) is utilized to retrieve the vibration information of the tested sample from an SMI signal. We are able to obtain both Young\u27s modulus and internal friction from a piece of an experimental SMI signal. This work provides a novel, simple non-destructive solution for simultaneous measurement of Young\u27s modulus and internal friction

Texturing In-Situ: N/F Dual-Doped hollow porous carbon nanospheres for advanced Li-S batteries

Heteroatom-doped hollow carbon nanostructures are one of the most promising sulfur hosts for high-performance lithium-sulfur (Li-S) batteries. However, finding a facile and controllable synthesis and enhancing their immobilization effect on polysulfides have been challenging. Herein, we propose a one-step in-situ reaction approach to synthesize N/F dual-doped hollow micro/mesoporous carbon nanospheres (NFHCs) as multifunctional sulfur host, which integrates the physical confinement of hollow porous structure and chemical adsorption/catalytic ability of N/F active sites to realize strong anchoring and accelerated conversion of poly-sulfides. This sulfur cathode based on NFHCs host with a high sulfur content of 80 wt% enables a superior high -rate capacity of 689 mAh g(-1) at 3C, accompanied by outstanding cycle life over 500 cycles at 2C with a capacity decay of only 0.05% per cycle and nearly 100% Coulombic efficiency. This work opens up new horizons to design nanostructured functional hollow carbons for advanced Li-S batteries

N/S Co-doped microporous carbon derived from PSSH-Melamine salt solution as cathode host for Lithium-Selenium batteries

Selenium cathode attracts great attention due to its high theoretical volumetric capacity and better electrical conductivity than sulfur cathode. Herein, N/S co-doped microporous carbon (NS-K-PC) is designed and prepared as Se host by a spray drying process of the poly(styrenesulfonic acid)-melamine salt solution followed by carbonization and activation process. The as-prepared NS-K-PC shows a very high micropore contribution of 94.8% in the total surface area, and a total N/S heteroatom doping level of 2.5 wt% in the carbon matrix. The NS-K-PC/Se cathode delivers a high reversible capacity of 499.2 mA h g(-1) at 0.1C, superior rate capacity of 324 mA h g(-1) at 8C, and great cycling stability with a capacity decay of 0.081% per cycle over 500 cycles at 1C. Additionally, a comparative study demonstrates that NS-K-PC/Se cathode with the carbonate-based electrolytes exhibit better cycling stability than those with ether-based electrolytes primarily resulted from a direct solid-solid conversion of Se to Li2Se bypassing the formation of soluble polyselenides. (C) 2021 Elsevier Inc. All rights reserved

Suppression of Power Angle Oscillation Among Synchronous Generators by Optimizing Steady–State Power of High-Voltage DC

In the power systems with high-voltage DC (HVDC) transmission, the angular oscillations among the synchronous generators (SGs) endanger the system security. The pre-fault power of the HVDC changes the power flow and affects the system dynamics, hence may be optimized to improve the system stability. However, the HVDC power does not appear in the system matrix, thus it is difficult to derive the analytical expression of the trajectory sensitivity (TS) for parameter optimization. Based on the power flow equations, the initial value of the TS is newly introduced in the sensitivities of the power angles of the SGs with respect to the intermediate variables and then to the DC powers. The imbalanced matrix of the TS is derived during the time-domain simulation. By setting the objective function as the integral of the square of the relative value of the SGs’ power angle deviation with time, and summing the trajectory sensitivity for all time steps, the gradient information of the objective function to the DC powers is newly derived. The optimization model is solved with the interior point method to adjust the steady-state HVDC powers. The effect of the power optimization on the angular oscillation is verified with the time-domain simulation. The numerical results show that the objective function is reduced by 37.92%, and the oscillation amplitude is reduced by 35%

An Improved Genetic Algorithm Based Robust Approach for Stochastic Dynamic Facility Layout Problem

This paper deals with stochastic dynamic facility layout problem under demand uncertainty in terms of material flow between facilities. A robust approach suggests a robust layout in each period as the most frequent one falling within a prespecified percentage of the optimal solution for multiple scenarios. Mont Carlo simulation method is used to randomly generate different scenarios. A mathematical model is established to describe the dynamic facility layout problem with the consideration of transport device assignment. As a solution procedure for the proposed model, an improved adaptive genetic algorithm with population initialization strategy is developed to reduce the search space and improve the solving efficiency. Different sized instances are compared with Particle Swarm Optimization (PSO) algorithm to verify the effectiveness of the proposed genetic algorithm. The experiments calculating the cost deviation ratio under different fluctuation level show the good performance of the robust layout compared to the expected layout

The Potential Antidepressant Action of Duloxetine Co-Administered with the TAAR1 Receptor Agonist SEP-363856 in Mice

Here, we explored the possible interaction between duloxetine and SEP-363856 (SEP-856) in depression-related reactions. The results showed that oral administration of duloxetine showed powerful antidepressant-like effects in both the forced swimming test (FST) and the suspension tail test (TST). SEP-856 orally administered alone also exerted an antidepressant-like effect in FST and TST, especially at doses of 0.3, 1, and 10 mg/kg. In addition, duloxetine (15 mg/kg) and SEP-856 (15 mg/kg) both showed antidepressant-like effects in the sucrose preference test (SPT). Most importantly, in the above experiments, compared with duloxetine alone, the simultaneous use of duloxetine and SEP-856 caused a more significant antidepressant-like effect. It is worth noting that doses of drug combination in FST and TST did not change the motor activities of mice in the open-field test (OFT). Thus, duloxetine and SEP-856 seem to play a synergistic role in regulating depression-related behaviors and might be beneficial for refractory depression