Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-23
Abstract： With the development of digital control technology, the traditional instrument and control system based on analog quantity in nuclear power plant is gradually replaced by full digital technology, and it is possible to use more complex and efficient advanced control technology. Making full use of the advantages of system information in the process of digitization of the whole plant to improve the automation level of nuclear power plant has gradually become the focus of research on pressurized water reactor control system. The control systems of Pressurizer Water Reactor (PWR) nuclear power plant are based on traditional Proportional Integral Derivative (PID) controller. Although there are studies on improving the control performance of PWR NPP control systems by advanced control algorithms, such as neural network control, fuzzy control and model predictive control, most of them only focus on the control system itself without considering the interconnection and coupling among multiple control systems. The operation task of PWR nuclear power plant needs to be coordinated by multiple control systems at the same time, and the effect of improving the overall performance by simply improving the performances of the controllers are limited. [Purpose]: To comprehensively consider the coupling effect amonge control systems, coordinate multiple control systems from the top level to optimize the overall control performances and achieve better task execution results, a setpoint decision optimization system is proposed. [Methods]: The intelligent decision system for PWR control system was optimized based on particle swarm optimization (PSO) method. The decision objective function and operation constraint conditions of the intelligent decision system were proposed. Considering the actual operation of PWR, the system optimized the setpoint offline and the intelligent decision operation was performed online according to the operation condition to provide the directions and amplitudes of the control targets for the underlying control systems. The typical operation process of the PWR NPP was taken as an example to carry out the simulation of the deigned intelligent decision-making system, and the simulation results were analyzed. [Results]: Compared with the control scheme using traditional setpoints, the ITSE (Integral of Time multiplied by the Square Error) of average coolant temperature, pressurizer level, pressurizer pressure and steam generator level decreased by 58.9%, 67.7%, 99.9% and 83.3%, respectively. The peak value decreased by 62.4%, 3.0%, 100% and 66.3% respectively. The simulation results show that the system proposed in this paper can effectively reduce the ITSE and peak value of the system. The overall control performances and safety margin of the control systems of PWR NPP are improved. In practical engineering practice, it can be combined with digital twin technology to use the characteristics of the twin that can synchronously reflect the real state of the system for more accurate online setpoint optimization, so as to achieve better control performance.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-04-29
Abstract： [Background]: In pursuit of promoting the diversified development of energy cooperation demands among countries participating in the Belt and Road Initiative and address the demand for secure and efficient energy supply along the Belt and Road Economic Belt, Xi'an Jiaotong University has actively innovated and proposed a small modular fluoride-salt-cooled high-temperature advanced reactor FuSTAR. [Purpose]: Although the conceptual design of FuSTAR has been completed, the reactor's ability to operate with load tracking and its safety are still need to be verified. [Methods]: The FuSTAR system was modeled and calculated by using VITARS software for detailed thermal-hydraulic and control system modeling, and its anti-interference characteristics and load operation tracking capability were analyzed in depth. [Results]: FuSTAR has demonstrated load tracking capability without relying on an external control system, mainly due to its inherent safety features, which allow the reactor to self-stabilize and regulate under load variations. With the adoption of a constant coolant outlet temperature control scheme, the load tracking capability of FuSTAR has been further enhanced. In the tests of 10% FP load step change and 5% FP/min rate linear load rise and fall, the overshoot of nuclear reactor power is strictly controlled within 5%. [Conclusions]: Because of the negative temperature reactivity feedback and the existence of control system, the small fluoride-salt-cooled high-temperature reactor has a good load tracking ability, which fully meets the requirements of safe operation of the reactor.
submitted time 2024-04-18
Abstract： [Background]: Spray atomization is widely used in nuclear power equipment to ensure its safe and stable operation. [Purpose]: This study aims to obtain the characteristics of the extended evolution of a liquid film formed by a droplet jet impacting a vertical wall. [Methods]: This paper conducted a study on droplet jet impinging on a wall based on Fluent DPM-to-VOF, and validated the accuracy of the simulation method using experimental images of two droplet falling processes. The research investigated the influence of droplet injection velocity and incident angle on the wall liquid film morphology, and obtained the variation of droplet splash rate with incident conditions. Furthermore, the effects of gravity, surface tension, velocity components, and other factors on the expansion process of liquid film morphology and droplet splash rate during droplet impact on the wall were analyzed. [Results]: The study found that increasing the injection velocity could enhance the disturbance to the liquid film, significantly increasing the contact area between the liquid film and the wall, as well as increasing the width and height of the liquid film area. Increasing the incident angle had a significant impact on the change of liquid film morphology, reflected in the increase in the width of the liquid film area and the decrease in the height of the liquid film area, leading to decreased stability of the liquid film surface. The splash rate increased with the increase of injection velocity and incident angle, with the incident angle having a greater impact on the splash rate. [Conclusions]: The study of jet impingement on the wall can lay the foundation for the subsequent study of wall cooling under the spraying.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2024-03-05 Cooperative journals: 《第八届海峡两岸暨港澳地区高校现代书院制教育论坛 》
Abstract：摘要党的十八大以来，习近平总书记对高校育人工作高度重视，强调要“把立德树人融入思想道德教育、文化知识教育、社会实践教育各环节”“要培养德智体美劳全面发展的社会主义建设者和接班人”的要求。 为推动学生思想教育工作，促进第二课堂发展新格局，在“五育”协调发展的基础上，实现各育目标相互之间的深度融合，发挥好德智体美劳五个方面兼容并蓄、同心同向的作用就要求做到五育融合，贯通发展。然而在第二课堂中，五育形式单一、学生主动性差、师资力量薄弱、思想政治教育时效性差、缺乏一定的体系和体制制度的问题逐渐显现。为此崇实书院联合各学院，以综合能力提升课程为抓手，破解难题:一是五育融合构筑全方位育人体系;二是名师入驻开拓新思路，朋辈助力携手助成长;三是班主任力量夯实新成效;四是以史为鉴，以笔为媒，使思政、党史教育“活”起来。
Subjects: Other Disciplines >> Synthetic discipline submitted time 2024-03-05 Cooperative journals: 《第八届海峡两岸暨港澳地区高校现代书院制教育论坛 》
Abstract：随着高等教育改革的深入，强化拔尖创新人才培养是我国教育事业的探索和尝试，而拔尖人才的思想政治教育是实现高等教育强国建设的关键环节。然而，在现有的书院制管理模式背景下，拔尖学生的思想政治教育却面临诸多现实问题，其中有双院协同育人机制等客观因素的制约，同时也受拔尖学生成长特点等主观因素的影响。鉴于此，文章总结了书院制下加强拔尖人才思政教育的意义及优势，分析了书院制下开展拔尖学生思政教育面临的困境，阐述了书院制下开展拔尖人才思政教育的探索与实践。
Subjects: Other Disciplines >> Synthetic discipline submitted time 2024-03-05 Cooperative journals: 《第八届海峡两岸暨港澳地区高校现代书院制教育论坛 》
Abstract：智媒时代的信息技术革新发展，改变了高校学生信息获取习惯、表达交流方式。受新冠疫情影响，高校学生对网络依赖程度加深，使得网络思想政治教育语境呈现新特点，主要表现为思维碎片化、信息茧房化与社交圈层化。网络思想政治教育语境引导要坚持问题导向、目标导向与效果导向，从融圈、建圈、出圈三维度做好网络思想政治教育。
Subjects: Other Disciplines >> Synthetic discipline submitted time 2024-03-05 Cooperative journals: 《第八届海峡两岸暨港澳地区高校现代书院制教育论坛 》
Abstract：近年来高校教育教学改革力度大，个性鲜明的“00”后成为高校主要群体，传统宿舍管理模式面临新挑战，难以适应高校教育改革和满足学生多样化需求。学生自主管理逐渐成为宿舍管理的新趋势，而书院制为宿舍管理模式革新带来契机。西安交通大学南洋书院创建以“宿生会+层议长”为核心的宿舍社区管理模式，在理念、组织、机制和内容层面革新，充分彰显学生主体性，满足学生自主管理需求，挖掘宿舍社区教育功能，共创平安、健康、文明社区。
Subjects: Other Disciplines >> Synthetic discipline submitted time 2024-03-05 Cooperative journals: 《第八届海峡两岸暨港澳地区高校现代书院制教育论坛 》
Abstract：书院制的蓬勃发展为高等教育人才培养赋予了新的生命力，提供了新的可能性。近年来，在国家提倡“三全育人”，强调“五育并举”的大背景下，单一的书院或学院教育侧重已很难全面满足新时代对人才的需求，因此，必须加强两院协同育人以保证人才培养的质效。本文创造性地借助于韦恩图、平面二维直角坐标系以及集合映射等数学模型，从两院存在关系、两院育人效果、两院对应关系三方面来探讨构析两院之间的“协同”关系，结合实际工作问题，有针对性地给出了“优化两院议事机制”“健全两院沟通队伍”“理顺两院工作流程”“夯实两院工作举措”四方面的优化协同建议，对于新时期持续探索和做好两院协同育人工作具有一定的积极意义。
Subjects: Dynamic and Electric Engineering >> Electrical Engineering Subjects: Mathematics >> Control and Optimization. submitted time 2022-08-07
Xiaodong Zheng
Baorong Zhou
Xiuli Wang
Bo Zeng
Jizhong Zhu
Haoyong Chen
Peizheng Xuan
Waisheng Zheng
Abstract： Quick-start generation units are critical devices and flexible resources to ensure a high penetration level of renewable energy in power systems. By considering the wind uncertainty, and both binary and continuous decisions of quick-start units within the intraday dispatch, we develop a Wasserstein-metric-based distributionally robust optimization model for the day-ahead network-constrained unit commitment (NCUC) problem with mixed integer recourse. We propose two feasible frameworks for solving the optimization problem. One approximates the continuous support of random wind power with finitely many events, the other leverages the extremal distributions instead. Both solution frameworks rely on the classic nested column-and-constraint generation (C&CG) method. It is shown that due to the sparsity of L1-norm Wasserstein metric, the continuous support of wind power generation could be represented by a discrete one with a small number of events, and the extremal distributions rendered are sparse as well. With this reduction, the distributionally robust NCUC model with complicated mixed-integer recourse problems can be efficiently handled by both solution frameworks. Numerical studies are carried out, demonstrating that the model considering quick-start generation units ensures unit commitment (UC) schedules to be more robust and cost effective, and the distributionally robust optimization method captures the wind uncertainty well in terms of out-of-sample tests.
Subjects: Psychology >> Social Psychology submitted time 2018-11-27
Abstract： " "
Peer Review Status:
Awaiting Review
Subjects: Psychology >> Social Psychology Subjects: Computer Science >> Natural Language Understanding and Machine Translation submitted time 2018-11-27
Abstract： "
Peer Review Status:Awaiting Review
Subjects: Biology >> Bioengineering submitted time 2017-09-20
Abstract： The current crisis of global warming is primarily attributed to CO2 production from excessive use of fossil fuels during recent decades, and has increased demand for renewable biofuels tremendously. Lipids are drawing considerable attention in relation to the production potential of biodiesel on the basis of their nontoxic, sustainable, and energy efficient proprieties. However, the high cost of microbial lipid produced by oleaginous microorganisms mainly stems from the high cost of glucose, which is estimated to be about 80% of the total medium cost. Therefore, considerable efforts have been directed toward minimizing the carbon source cost and finding new alternative carbon sources. In this report, several low-cost biomass including food-waste-derived volatile fatty acids, lignocellulose-based sugars, and methane derived from biogas were investigated for lipid production. After developing the culture modes and optimizing the culture conditions, both high lipid titer and productivity were achieved in high cell density cultures of different microorganisms using various carbon sources.
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