Robust power control design for a small pressurized water reactor using an H infinity mixed sensitivity method

Yan Xu,Wang Pengfei,Qing Junyan,Wu Shifa,Zhao Fuyu 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7

The objective of this study is to design a robust power control system for a small pressurized water reactor (PWR) to achieve stable power operations under conditions of external disturbances and internal model uncertainties. For this purpose, the multiple-input multiple-output transfer function models of the reactor core at five power levels are derived from point reactor kinetics equations and the Mann's thermodynamic model. Using the transfer function models, five local reactor power controllers are designed using an H infinity (H∞) mixed sensitivity method to minimize the core power disturbance under various uncertainties at the five power levels, respectively. Then a multimodel approach with triangular membership functions is employed to integrate the five local controllers into a multimodel robust control system that is applicable for the entire power range. The performance of the robust power system is assessed against 10% of full power (FP) step load increase transients with coolant inlet temperature disturbances at different power levels and large-scope, rapid ramp load change transient. The simulation results show that the robust control system could maintain satisfactory control performance and good robustness of the reactor under external disturbances and internal model uncertainties, demonstrating the effective of the robust power control design.

Ultimate strength behavior of steel-concrete-steel sandwich beams with ultra-lightweight cement composite, Part 1: Experimental and analytical study

Jia-Bao Yan,J.Y. Richard Liew,Min-Hong Zhang,Junyan Wang 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.6

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of 1450 kg/m³ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.

Yap signalling regulates ductular reactions in mice with CRISPR/Cas9-induced glycogen storage disease type Ia

Yixia Xie,Baowei Hu,Yue Gao,Yaxin Tang,Guohe Chen,Jiayuan Shen,Zhikai Jiang,He Jiang,Jiwei Han,Junyan Yan,Lifang Jin 한국통합생물학회 2022 Animal cells and systems Vol.26 No.6

Glycogen storage disease type Ia (GSD-Ia) is caused by a deficiency in the glucose-6-phosphatase (G6Pase, G6pc) enzyme, which catalyses the final step of gluconeogenesis and glycogenolysis. Accumulation of G6pc can lead to an increase in glycogen and development of fatty liver. Ductular reactions refer to the proliferation of cholangiocytes and hepatic progenitors, which worsen fatty liver progress. To date, however, ductular reactions in GSD-Ia remain poorly understood. Here, we studied the development and potential underlying mechanism of ductular reactions in GSD-Ia in mice. We first generated GSD-Ia mice using CRISPR/Cas9 to target the exon 3 region of the G6pc gene. The typical GSD-Ia phenotype in G6pc−/− mice was then analysed using biochemical and histological assays. Ductular reactions in G6pc−/− mice were tested based on the expression of cholangiocytic markers cytokeratin 19 (CK19) and epithelial cell adhesion molecule (EpCAM). Yes-associated protein 1 (Yap) signalling activity was measured using western blot (WB) analysis and quantitative real-time polymerase chain reaction (qRT-PCR). Verteporfin was administered to the G6pc−/− mice to inhibit Yap signalling. The CRISPR/Cas9 system efficiently generated G6pc−/− mice, which exhibited typical GSD-Ia characteristics, including retarded growth, hypoglycaemia, and fatty liver disease. In addition, CK19- and EpCAM-positive cells as well as Yap signalling activity were increased in the livers of G6pc−/− mice. However, verteporfin treatment ameliorated ductular reactions and decreased Yap signalling activity. This study not only improves our understanding of GSD-Ia pathophysiology, but also highlights the potential of novel therapeutic approaches for GSD-Ia such as drug targeting of ductular reactions.

Base Station Placement for Wireless Sensor Network Positioning System via Lexicographical Stratified Programming

( Jun Yan ),( Kegen Yu ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.11

This paper investigates optimization-based base station (BS) placement. An optimization model is defined and the BS placement problem is transformed to a lexicographical stratified programming (LSP) model for a given trajectory, according to different accuracy requirements. The feasible region for BS deployment is obtained from the positioning system requirement, which is also solved with signal coverage problem in BS placement. The LSP mathematical model is formulated with the average geometric dilution of precision (GDOP) as the criterion. To achieve an optimization solution, a tolerant factor based complete stratified series approach and grid searching method are utilized to obtain the possible optimal BS placement. Because of the LSP model utilization, the proposed algorithm has wider application scenarios with different accuracy requirements over different trajectory segments. Simulation results demonstrate that the proposed algorithm has better BS placement result than existing approaches for a given trajectory.

A Differential Privacy Approach to Preserve GWAS Data Sharing based on A Game Theoretic Perspective

Jun Yan,Ziwei Han,Yihui Zhou,Laifeng Lu 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.3

Genome-wide association studies (GWAS) aim to find the significant genetic variants for common complex disease. However, genotype data has privacy information such as disease status and identity, which make data sharing and research difficult. Differential privacy is widely used in the privacy protection of data sharing. The current differential privacy approach in GWAS pays no attention to raw data but to statistical data, and doesn’t achieve equilibrium between utility and privacy, so that data sharing is hindered and it hampers the development of genomics. To share data more securely, we propose a differential privacy preserving approach of data sharing for GWAS, and achieve the equilibrium between privacy and data utility. Firstly, a reasonable disturbance interval for the genotype is calculated based on the expected utility. Secondly, based on the interval, we get the Nash equilibrium point between utility and privacy. Finally, based on the equilibrium point, the original genotype matrix is perturbed with differential privacy, and the corresponding random genotype matrix is obtained. We theoretically and experimentally show that the method satisfies expected privacy protection and utility. This method provides engineering guidance for protecting GWAS data privacy.

The Effect of H2O2/Fe2+ Catalytic Oxidation System on the Morphology, Structure and Properties of Flake-Like Poly(2,3-dimethylaniline)

Jun Yan,Li Ma,Mengyu Gan,Xiao Li,Zhitao Li,Jihai Tang,Ying Tu,Haifeng Hu 한국고분자학회 2014 Macromolecular Research Vol.22 No.8

In this work, flake-like poly(2,3-dimethylaniline) (P(2,3-DMA)) with enhanced thermal stability andanticorrosive ability was synthesized by in situ polymerization using H2O2/Fe2+ catalytic oxidation system, comparingwith traditional oxidant ammonium persulfate (APS) synthetic method. The structure and morphology of thesamples were characterized Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD) and field-emissionscanning electron microscope (FESEM). The experimental results demonstrated that using H2O2/Fe2+ catalytic oxidationsystem was more inclined to form the two-dimensional P(2,3-DMA) flakes. The enhancement in thermostabilityand corrosion resistance was attributed to the formation of phenazine-like structures in the polymer chains,which could serve as templates to form the flake-like morphology. In addition, using H2O2/Fe2+ catalytic oxidationsystem is more environmental friendly than the APS method that can avoid ammonium pollution on aquatic life aswell as waters.

An Interference Matrix Based Approach to Bounding Worst-Case Inter-Thread Cache Interferences and WCET for Multi-Core Processors

Jun Yan,Wei Zhang 한국정보과학회 2011 Journal of Computing Science and Engineering Vol.5 No.2

Different cores typically share the last-level cache in a multi-core processor. Threads running on different cores may interfere with each other. Therefore, the multi-core worst-case execution time (WCET) analyzer must be able to safely and accurately estimate the worst-case inter-thread cache interference. This is not supported by current WCET analysis techniques that manly focus on single thread analysis. This paper presents a novel approach to analyze the worst-case cache interference and bounding the WCET for threads running on multi-core processors with shared L2 instruction caches. We propose to use an interference matrix to model inter-thread interference, on which basis we can calculate the worst-case inter-thread cache interference. Our experiments indicate that the proposed approach can give a worst-case bound less than 1%, as in benchmark fib-call, and an average 16.4% overestimate for threads running on a dual-core processor with shared-L2 cache. Our approach dramatically improves the accuracy of WCET overestimatation by on average 20.0% compared to work.

Computing and Reducing Transient Error Propagation in Registers

Jun Yan,Wei Zhang 한국정보과학회 2011 Journal of Computing Science and Engineering Vol.5 No.2

Recent research indicates that transient errors will increasingly become a critical concern in microprocessor design. As embedded processors are widely used in reliability-critical or noisy environments, it is necessary to develop cost-effective fault-tolerant techniques to protect processors against transient errors. The register file is one of the critical components that can significantly affect microprocessor system reliability, since registers are typically accessed very frequently, and transient errors in registers can be easily propagated to functional units or the memory system, leading to silent data error (SDC) or system crash. This paper focuses on investigating the impact of register file soft errors on system reliability and developing cost-effective techniques to improve the register file immunity to soft errors. This paper proposes the register vulnerability factor (RVF) concept to characterize the probability that register transient errors can escape the register file and thus potentially affect system reliability. We propose an approach to compute the RVF based on register access patterns. In this paper, we also propose two compiler-directed techniques and a hybrid approach to improve register file reliability cost-effectively by lowering the RVF value. Our experiments indicate that on average, RVF can be reduced to 9.1% and 9.5% by the hyperblock-based instruction re-scheduling and the reliability-oriented register assignment respectively, which can potentially lower the reliability cost significantly, without sacrificing the register value integrity.

Bounding Worst-Case Performance for Multi-Core Processors with Shared L2 Instruction Caches

Jun Yan,Wei Zhang 한국정보과학회 2011 Journal of Computing Science and Engineering Vol.5 No.1

As the first step toward real-time multi-core computing, this paper presents a novel approach to bounding the worst-case performance for threads running on multi-core processors with shared L2 instruction caches. The idea of our approach is to compute the worst-case instruction access interferences between different threads based on the program control flow information of each thread, which can be statically analyzed. Our experiments indicate that the proposed approach can reasonably estimate the worst-case shared L2 instruction cache misses by considering the inter-thread instruction conflicts. Also, the worst-case execution time (WCET) of applications running on multi-core processors estimated by our approach is much better than the estimation by simply assuming all L2 instruction accesses are misses.

MAPPING THE IN-FEED NATIVE ADVERTISING RESEARCH: A BIBLIOMETRIC REVIEW AND DIRECTIONS FOR FUTURE RESEARCH

Jun Yan,Chenying Hai,Zhen Li,Hewei Lv 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07

Over the past decade, in-feed native advertising has become one of the most popular forms of online advertising, attracting attention from both academia and industry. Compared to traditional online ads, in-feed native ads are less intrusive and have more engaging content, effectively reducing users' tendency to avoid ads and improving advertising effectiveness. Despite existing review studies, most of them focus on specific aspects of in-feed native advertising, such as ad identification, disclosure, or regulation, and lack an overview of the relevant literature. Moreover, with the diversified development of digital media forms, the widespread application of AI technologies, and the improvement of consumers' ad literacy, in-feed native ad research faces new issues and practical challenges. Thus, a systematic review of existing research is necessary to identify valuable future research directions.