High‑frequency planar transformer optimal design and analysis

Yu Tang,Guanghui Wang,Zhe Shi,Jincai Niu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.2

Due to the rapid development of modern industry, there is an increasing demand for isolated switching power supplies (SMPS) with a high efficiency and a high power density. Magnetic components, which occupy most of the converter volume, have been a key bottleneck in achieving high power density. This paper presents an optimal design method for high power density planar transformers. Applying the principle of flux cancellation, a matrix transformer that originally needed an independent magnetic core was integrated into a single magnetic core to reduce the volume of the core. Meanwhile, a loss model of the transformer is established, and an optimized design method of the winding structure is given according to that model to further reduce the winding loss of the transformer. Finally, an LLC converter with a resonant frequency of 1 MHz is designed to verify the practical performance of the proposed transformer.

Simple symmetric switched inductor high step‑down converter

Yu Tang,Xuran Rong,Jiarong Kan,Yun Zhang,Lin Jiang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.10

The voltage gain of a traditional buck converter is finite due to the high voltage across the semiconductor and reduced efficiency. A non-isolated high step-down DC–DC converter based on symmetric switched inductors is proposed in this paper. The connection of inductors in series or in parallel is controlled by switches to improve the conversion ratio. The converter has many beneficial characteristics, such as high step-down, reduced voltage stresses, and high efficiency. Moreover, it can realize voltage balance on the switches. The voltage on the switch does not oscillate and the loss of the switches is reduced. Therefore, the efficiency of the whole topology is improved. This paper discusses the operation principle, modes analysis, voltage gain analysis, voltage stress analysis, output ripple analysis, loss analysis, comparative analysis and design considerations. The correctness of the theoretical analysis of the proposed converter is verified by a laboratory prototype, and its peak efficiency reaches 96.5%.

Response of Esophagus to High and Low Temperatures in Patients With Achalasia

( Yutang Ren ),( Meiyun Ke ),( Xiucai Fang ),( Liming Zhu ),( Xiaohong Sun ),( Zhifeng Wang ),( Ruifeng Wang ),( Zhao Wei ),( Ping Wen ),( Haiwei Xin ),( Min Chang ) 대한소화기기능성질환·운동학회 2012 Journal of Neurogastroenterology and Motility (JNM Vol.18 No.4

Background/Aims Achalasia patients would feel exacerbated dysphagia, chest pain and regurgitation when they drink cold beverages or eat cold food. But these symptoms would relieve when they drink hot water. Reasons are unknown. Methods Twelve achalasia patients (mean age, 34 ± 10 years, F:M, 3:9) who never had any invasive therapies were chosen from Peking Union Medical College Hospital. They were asked to fill in the questionnaire on eating habits including food temperature and related symptoms and to receive high-resolution manometry examination. The exam was done in 2 separated days, at swallowing room temperature (25oC) then hot (50oC) water, and at room temperature (25oC) then cold (2oC) water, respectively. Parameters associated with esophageal motility were analyzed. Results Most patients (9/12) reported discomfort when they ate cold food. All patients reported no additional discomfort when they ate hot food. Drinking hot water was effective in 5/8 patients who ever tried to relieve chest pain attacks. On manometry, cold water increased lower esophageal sphincter (LES) resting pressure (P = 0.003), and prolonged the duration of esophageal body contraction (P = 0.002). Hot water decreased LES resting pressure and residue pressure during swallow (P = 0.008 and P = 0.002), increased LES relaxation rate (P = 0.029) and shortened the duration of esophageal body contraction (P = 0.003). Conclusions Cold water could increase LES resting pressure, prolong the contraction duration of esophageal body, and exacerbate achalasia symptoms. Hot water could reduce LES resting pressure, assist LES relaxation, shorten the contraction duration of esophageal body and relieve symptoms. Thus achalasia patients are recommended to eat hot and warm food and avoid cold food. (J Neurogastroenterol Motil 2012,18:391-398)

Myotomy of Distal Esophagus Influences Proximal Esophageal Contraction and Upper Esophageal Sphincter Relaxation in Patients with Achalasia After Peroral Endoscopic Myotomy

( Yutang Ren ),( Xiaowei Tang ),( Fengping Chen ),( Zhiliang Deng ),( Jianuan Wu ),( Soma Nei ),( Bo Jiang ),( Wei Gong ) 대한소화기기능성질환·운동학회 2016 Journal of Neurogastroenterology and Motility (JNM Vol.22 No.1

Background/Aims The motility change after peroral endoscopic myotomy (POEM) in achalasia is currently focused on lower esophageal sphincter (LES). This study aims to investigate the correlation of motility response between distal and proximal esophagus after POEM. Methods A total of 32 achalasia patients who received POEM and high-resolution manometry (HRM) were included for analysis. Eckardt score was used to assess symptom improvement. HRM was applied for studying motility. Main parameters analyzed were (1) LES: resting pressure (restP), 4-second integrated relaxation pressure; (2) esophageal body (EB): contractile integral of distal segment with myotomy (CI-DM) and proximal segment without myotomy (CI-PNM); and (3) upper esophageal sphincter (UES): relaxation pressure (UES-RP). Results There were 6 type I, 17 type II, and 9 type III achalasia patients included for analysis. (1) Eckardt score, LES tone, CI-DM, CI-PNM and UES-RP were reduced remarkably after POEM (P < 0.001). (2) no significant correlation was noted between LES tone and contractile intergral of EB. (3) a positive linear correlation of CI-DM and CI-PNM changes was detected (P < 0.001). (4) the change of UES-RP was positively correlated with the change of contractile integral of EB (P < 0.001). Conclusions Myotomy of the distal esophagus would attenuate proximal EB contraction and assist UES relaxation in achalasia patients after POEM. (J Neurogastroenterol Motil 2016;22:78-85)

Toward a Common Heritage of All Mankind

Lin Yutang The Academy of Korean Studies 1968 Korea Journal Vol.8 No.7

A pilot-scale test on the treatment of biological pretreated leachate by the synergy of ozonation-biological treatment-catalytic ozonation

Yuanmei Chen,Yutang Xiao,Guanping Wang,Wei Shi,Linquan Sun,Yanfang Chen,Aichun Miao 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.4

In this pilot-scale test, the ozonation-biological treatment-catalytic ozonation system was performed to treat complex organics and highly-concentrated total nitrogen (TN) in biological pretreated incineration leachate. The test results showed that the ratio of five-day biochemical oxygen demand (BOD5) / chemical oxygen demand (COD) increased from 0.059 to 0.237, which indicated that the concentration of biodegradable COD (CODbio) increased by ozonation pre-treatment process. In addition, the TN removal mainly occurred in anaerobic zone due to direct denitrification by the activated bacteria, which were domesticated through different influent ratio. Moreover, it was necessary to add catalytic ozonation process to reach higher direct effluent discharge criteria. After 60 days repeated debugging, the removal rate of COD and TN reached 88.5% and 98.2%, respectively. Finally, the total cost of this system was ￥ 6.65 /㎥ ($ 0.95 /㎥), which was acceptable for the treatment of biological pretreated leachate. This pilot-scale test could provide some guiding information for the treatment of leachate containing highly-concentrated TN with low CODbio/N by the composite system.

Endoscopic Submucosal Tunnel Dissection for Upper Gastrointestinal Submucosal Tumors Originating from the Muscularis Propria Layer: A Single-Center Study

( Xiaowei Tang ),( Yutang Ren ),( Silin Huang ),( Qiaoping Gao ),( Jieqiong Zhou ),( Zhengjie Wei ),( Bo Jiang ),( Wei Gong ) 대한간학회 2017 Gut and Liver Vol.11 No.5

Background/Aims: In recent years, endoscopic submucosal tunnel dissection (ESTD) has gained popularity worldwide. The aim of this study was to evaluate the safety and efficacy of ESTD in treating upper gastrointestinal submucosal tu-mors (SMTs) in a large-volume endoscopic center. Methods: Patients with SMTs were enrolled in this study between January 2012 and January 2015. Demographic data, clinical data, and treatment outcome were collected and analyzed. Results: Seventy SMTs originating from the muscularis pro-pria (MP) layer were identified in 69 patients. All patients successfully underwent the ESTD procedure. The mean procedure time was 49.0±29.5 minutes, and the mean tu-mor size was 18.7±7.2 mm. Among all lesions, the majority (70.0%) were located in the esophagus, 12.9% in the cardia, and 17.1% in the stomach. Complete resection was achieved in 67 lesions (95.7%). Perforation occurred in three patients (4.3%), who were treated by endoclips. Pneumothorax oc-curred in two patients (2.9%) and was successfully managed by thoracic drainage. During a median follow-up of 18.1 months, patients were free of local recurrence or distant metastasis. Conclusions: Our results demonstrated the fea-sibility and safety of ESTD in treating upper gastrointestinal SMTs originating from the MP layer. Large-scale comparative studies with other treatment methods should be conducted in the future. (Gut Liver 2017;11:620-627)

Output Feedback Control of Two-dimensional Polynomial Fuzzy Networked-Control-Systems

Lizhen Li,Yutang Wu,Deshi Hu 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11

In this paper, the output feedback control problem is considered for two-dimensional(2-D) continuous polynomial fuzzy networked-control-systems(NCS). Firstly, a 2-D polynomial fuzzy NCS is proposed, with the 2-D polynomial Roesser model as the local model. And the communication delay is modeled by Bernoulli process. Then, by using stochastic analysis theory, the output feedback controller is designed, such that the resulting closed-loop 2-D continuous polynomial fuzzy NCS is stochastically stable. The developed SOS conditions are convex and hence can be numerically solved by the SOSTOOLS. Finally, a simulation example is given to illustrate the effectiveness and of the proposed approach.

Efficacy and Safety of Peroral Endoscopic Myotomy in Achalasia Patients with Failed Previous Intervention: A Systematic Review and Meta-analysis

( Shali Tan ),( Chunyu Zhong ),( Yutang Ren ),( Xujuan Luo ),( Jin Xu ),( Xiangsheng Fu ),( Yan Peng ),( Xiaowei Tang ) 대한소화기학회 2021 Gut and Liver Vol.15 No.2

Peroral endoscopic myotomy (POEM) has emerged as a rescue treatment for recurrent or persistent achalasia after failed initial management. Therefore, we aimed to investigate the efficacy and safety of POEM in achalasia patients with failed previous intervention. We searched the MEDLINE, Embase, Cochrane, and PubMed databases using the queries “achalasia,” “peroral endoscopic myotomy,” and related terms in March 2019. Data on technical and clinical success, adverse events, Eckardt score and lower esophageal sphincter (LES) pressure were collected. The pooled event rates, mean differences (MDs) and risk ratios (RR) were calculated. A total of 15 studies with 2,276 achalasia patients were included. Overall, the pooled technical success, clinical success and adverse events rate of rescue POEM were 98.0% (95% confidence interval [CI], 96.6% to 98.8%), 90.8% (95% CI, 88.8% to 92.4%) and 10.3% (95% CI, 6.6% to 15.8%), respectively. Seven studies compared the clinical outcomes of POEM between previous failed treatment and the treatment naïve patients. The RR for technical success, clinical success, and adverse events were 1.00 (95% CI, 0.98 to 1.01), 0.98 (95% CI, 0.92 to 1.04), and 1.17 (95% CI, 0.78 to 1.76), respectively. Overall, there was significant reduction in the pre- and post-Eckardt score (MD, 5.77; p<0.001) and LES pressure (MD, 18.3 mm Hg; p<0.001) for achalasia patients with failed previous intervention after POEM. POEM appears to be a safe, effective and feasible treatment for individuals who have undergone previous failed intervention. It has similar outcomes in previously treated and treatment-naïve achalasia patients. (Gut Liver 2021;15:153-167)

Methylation of methyltrichlorosilane with methyl chloride over active metals and activated carbon

Yanjun Liu,Yiqian Jiang,Weiguang Chen,Yutang Shen,Yonghai Feng,Lingqin Shen,Aili Wang,Tingshun Jiang,Zhanao Wu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.12

Gas phase methylation of methyltrichlorosilane with methyl chloride to high-valued dimethyldichlorosilane was carried out by using metallic aluminum as a chlorine acceptor in the co-presence of activated carbon, tin, and zinc. The addition of activated carbon in metallic aluminum significantly enhanced the methylation of methyltrichlorosilane,and dimethyldichlorosilane was dominantly produced. Activated carbon played a catalyst role in the methylation reaction. When active metals, such as tin and zinc, were added in the mixture of aluminum and activated carbon,the active metals and activated carbon synergistically catalyzed the methylation of methyltrichlorosilane with methyl chloride toward the formation of dimethyldichlorosilane.