Research on fl ow characteristics in supercritical water natural circulation: Infl uence of heating power distribution

Dongliang Ma,Tao Zhou,Xiang Feng,Yanping Huang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.7

There are many parameters that affect the natural circulation flow, such as height difference, heatingpower size, pipe diameter, system pressure and inlet temperature and so on. In general analysis theheating power is often regarded as a uniform distribution. The ANSYS-CFX numerical analysis softwarewas used to analyze the flow heat transfer of supercritical water under different heating power distributionconditions. The distribution types of uniform, power increasing, power decreasing and sinefunction are investigated. Through the analysis, it can be concluded that different power distribution hasa great influence on the flow of natural circulation if the total power of heating is constant. It was foundthat the peak flow of supercritical water natural circulation is maximal when the distribution of heatingpower is monotonically decreasing, minimal when it is monotonically increasing, and moderate atuniform or the sine type of heating. The simulation results further reveal the supercritical water underdifferent heat transfer conditions on its flow characteristics. It can provide certain theory reference andsystem design for passive residual heat removal system about supercritical water.

Research on prediction and analysis of supercritical water heat transfer coefficient based on support vector machine

Dongliang Ma,Yi Li,Tao Zhou,Yanping Huang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.11

In order to better perform thermal hydraulic calculation and analysis of supercritical water reactor, based on the experimental data of supercritical water, the model training and predictive analysis of the heat transfer coefficient of supercritical water were carried out by using the support vector machine (SVM) algorithm. The changes in the prediction accuracy of the supercritical water heat transfer coefficient are analyzed by the changes of the regularization penalty parameter C, the slack variable epsilon and the Gaussian kernel function parameter gamma. The predicted value of the SVM model obtained after parameter optimization and the actual experimental test data are analyzed for data verification. The research results show that: the normalization of the data has a great influence on the prediction results. The slack variable has a relatively small influence on the accuracy change range of the predicted heat transfer coefficient. The change of gamma has the greatest impact on the accuracy of the heat transfer coefficient. Compared with the calculation results of traditional empirical formula methods, the trained algorithm model using SVM has smaller average error and standard deviations. Using the SVM trained algorithm model, the heat transfer coefficient of supercritical water can be effectively predicted and analyzed.

Research Progress on Non-coding RNAs in Cholesteatoma of the Middle Ear

Dongliang Liu,Hang Zhang,Xiulan Ma,Yaodong Dong 대한이비인후과학회 2023 Clinical and Experimental Otorhinolaryngology Vol.16 No.2

Cholesteatoma of the middle ear is a common disease in otolaryngology that is receiving increasing attention. It is estimat-ed that over five million people around the world have suffered from middle ear cholesteatoma. The annual incidence ofmiddle ear cholesteatoma has been reported to be 9.2 per 100,000 in adults and 3 per 100,000 in children. Without timelydiscovery and intervention, cholesteatomas can become perilously large and damage intratemporal structures, causing vari-ous intracranial and extracranial complications. No practical nonsurgical treatments are currently available. Although multi-ple hypotheses exist, research directions have consistently focused on cell proliferation, apoptosis, and bone destruction. Non-coding RNAs (ncRNAs), especially microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs),have recently received increasing attention because of their key roles in gene expression, cell cycle regulation, and the de-velopment of many diseases. Although ncRNAs are not involved in protein translation, they are abundant in the genome,with only approximately 2% of genes encoding proteins and the remaining approximately 98% encoding ncRNAs. Thepurpose of this review is to summarize the current state of knowledge regarding the specific role of ncRNAs in middle earcholesteatoma.

Development of a Novel Multiple Cross-Linking Spiral Amplification for Rapid and Sensitive Detection of HPV16 DNA

( Donghong Zhang ),( Dongliang Liu ),( Bing Liu ),( Xiulan Ma ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.4

There has been increasing interest in the head and neck squamous cell carcinoma (HNSCC) that is caused by high-risk human papillomavirus (HR-HPV) and has posed a significant challenge to Otolaryngologists. A rapid, sensitive, and reliable method is required for the detection of HR-HPV in clinical specimens to prevent and treat HPV-induced diseases. In this study, a multiple cross-linking spiral amplification (MCLSA) assay was developed for the visual detection of HPV-16. In the MCLSA assay, samples were incubated under optimized conditions at 62°C for 45 min, and after mixing with the SYBR Green I (SGI) dye, the positive amplicons showed bright green fluorescence while the negative amplicons exhibited no obvious change. The specificity test revealed that the developed MCLSA technique had high specificity and could effectively distinguish all five HPV-16 strains from other pathogenic microorganisms. In terms of analytical sensitivity, the limit of detection (LoD) of MCLSA assay was approximately 5.4 × 10¹ copies/tube, which was 10-fold more sensitive than loopmediated isothermal amplification (LAMP) and RT-PCR. The detection results of laryngeal cancer specimens collected from 46 patients with suspected HPV infection in the Liaoning region demonstrated that the positive detection rates of MCLSA and hybridized capture 2 kit were 32.61% (15/46). The true positive rate of the MCLSA assay was higher than that of RT-PCR (100% vs. 93.33%) and LAMP (100% vs. 86.67%). Therefore, the MCLSA assay developed in the present study could be a potentially useful tool for the point-of-care (PoC) diagnosis of HR-HPV, especially in resourcelimited countries.

Novel Method for Circulating Current Suppression in MMCs Based on Multiple Quasi-PR Controller

Jian Qiu,Lijun Hang,Dongliang Liu,Shengbao Geng,Xiaonan Ma,Zhen Li 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

An improved circulating current suppression control method is proposed in this paper. In the proposed controller, an outer loop of the average capacitor voltage control model is used to balance the sub-module capacitor voltage. Meanwhile, an individual voltage balance controller and an arm voltage balance controller are also used. The DC and harmonic components of the circulating current are separated using a low pass filter. Therefore, a multiple quasi-proportional-resonant (multi-quasi-PR) controller is introduced in the inner loop to eliminate the circulating harmonic current, which mainly contains second-order harmonic but also contains other high-order harmonics. In addition, the parameters of the multi-quasi-PR controller are designed in the discrete domain and an analysis of the stability characteristic is given in this paper. In addition, a simulation model of a three-phase MMC system is built in order to confirm the correctness and superiority of the proposed controller. Finally, experiment results are presented and compared. These results illustrate that the improved control method has good performance in suppressing circulating harmonic current and in balancing the capacitor voltage.

Novel Method for Circulating Current Suppression in MMCs Based on Multiple Quasi-PR Controller

Qiu, Jian,Hang, Lijun,Liu, Dongliang,Geng, Shengbao,Ma, Xiaonan,Li, Zhen The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

An improved circulating current suppression control method is proposed in this paper. In the proposed controller, an outer loop of the average capacitor voltage control model is used to balance the sub-module capacitor voltage. Meanwhile, an individual voltage balance controller and an arm voltage balance controller are also used. The DC and harmonic components of the circulating current are separated using a low pass filter. Therefore, a multiple quasi-proportional-resonant (multi-quasi-PR) controller is introduced in the inner loop to eliminate the circulating harmonic current, which mainly contains second-order harmonic but also contains other high-order harmonics. In addition, the parameters of the multi-quasi-PR controller are designed in the discrete domain and an analysis of the stability characteristic is given in this paper. In addition, a simulation model of a three-phase MMC system is built in order to confirm the correctness and superiority of the proposed controller. Finally, experiment results are presented and compared. These results illustrate that the improved control method has good performance in suppressing circulating harmonic current and in balancing the capacitor voltage.

Research on heat transfer coefficient of supercritical water based on factorial and correspondence analysis

Xiang Feng,Tao Zhou,Jialei Zhang,Boya Zhang,Dongliang Ma 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7

The study of heat transfer coefficient of supercritical water plays an important role in improving the heat transfer efficiency of the reactor. Taking the supercritical natural circulation experimental bench as the research object, the effects of power, flow, pipe diameter and mainstream temperature on the heat transfer coefficient of supercritical water were studied. At the same time, the experimental data of Chen Yuzhou's supercritical water heat transfer coefficient was collected. Through the factorial design method, the influence of different factors and their interactions on the heat transfer coefficient of supercritical water is analyzed. Through the corresponding analysis method, the influencing factors of different levels of heat transfer coefficient are analyzed. It can be found: Except for the effects of flow rate, power, powertemperature and temperature, the influence of other factors on the natural circulation heat transfer coefficient of supercritical water is negligible. When the heat transfer coefficient is low, it is mainly affected by the pipe diameter. As the heat transfer coefficient is further increased, it is mainly affected by temperature and power. When the heat transfer coefficient is at a large level, the influence of the flow rate is the largest at this time

Evaluation of Critical Current Density of FeAs-based Superconductors

Edmund S. Otabe,Masaru Kiuchi,Teruo Matsushita,Baorong Ni,Yanpeng Qi,Lei Wang,Zhaoshun Gao,Dongliang Wang,Xianping Zhang,Yanwei Ma,Yasuyuki Nakajima,Tsuyoshi Tamegai 한국초전도저온학회 (구 한국초전도저온공학회) 2012 한국초전도저온공학회논문지 Vol.14 No.2

Quantitative Stability Analysis of an Unmanned Tethered Quadrotor

Dong Liang,Li Ding,Mingyue Lu,Rui Ma,Jie Cao 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.3

Tethered quadrotors, unmanned aerial quadrotors connected to a fixed point via tether cables, have been widely applied in numerous aerial tasks. However, their structural parameters and external disturbances give rise to dynamic stability issues, resulting in uncontrolled autonomous flight, shaking, and vibrating. Thus, this article investigates the quantitative stability of a tethered quadrotor using the Lyapunov exponent approach. First, a mathematical model of the tethered quadrotor is developed, and its dynamic stability is quantified to verify the rationality of the designed physical prototype and enhance the aerial system’s stability. Both simulation and experimental results show that the dynamic stability during the landing phase is better than that during takeoff. Finally, optimizing the structural parameters enhances the dynamic stability, which is sensitive to cable length, wind gusts, and yaw angle.