An Active Damping Scheme Based on a Second Order Resonant Integrator for LCL-Type Grid-Connected Converters

Chen Chen,Jian Xiong,Kai Zhang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.4

This paper proposes a novel active damping scheme to suppress LCL-filter resonance with only grid-current feedback control in grid-connected voltage-source converters. The idea comes from the concept of the model reference adaptive control (MRAC). A detailed theoretical derivation is given, and the effectiveness of this method is explained based on its physical nature. According to the control structure of this method, the active damping compensator, which is essentially a second order resonant integrator (SORI) filter, provides an effective solution to damp LCL resonance and to eliminate the need for additional sensors. Compared with extra feedback methods, the cost and complexity are reduced. A straightforward tuning procedure for the active damping method has been presented. A stability analysis is illustrated in the discrete domain while considering a one-step delay. Finally, experimental results are presented to validate the analysis and to demonstrate the good performance of the proposed method.

Electron-Electron Interactions in a Two-Dimensional Electron Systemin an Al0.15Ga0.85N/GaN Heterostructure Grown on p-Type Si

Jian-Zhe Huang,Li-Hung Lin,Chin-An Chang,Chi-Te Liang,Kuang Yao Chen,Kui-Ming Chen,N. C. Chen,P. H. Chang,Shiou-Shian Han,Zhi-Hao Sun 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3

We report on experimental studies of an Al$_{0.15}$Ga$_{0.85}$N/GaN high-electron-mobility transistor structure grown on a $p$-type Si (111) substrate. This structure is compatible with complementary metal-oxide-semiconductor (CMOS) technology and, thus, has great potential device applications. The low-temperature magnetoresistivity shows a parabolic dependence on the applied perpendicular magnetic field. This effect is ascribed to electron-electron interaction (EEI) effects in a weakly-disordered two-dimensional system. Our experimental results agree with the EEI theory when the correction term in the ballistic region has been subtracted.

Listeria monocytogenes Serovar 4a is a Possible Evolutionary Intermediate Between L. monocytogenes Serovars 1/2a and 4b and L. innocua

Jian Shun Chen,Ling Li Jiang,Xue Yan Chen,Xiao Kai Luo,Yang Chen,Ying Yu,Guo Ming Tian,Dong You Liu,Wei Huan Fang 한국미생물 · 생명공학회 2009 Journal of microbiology and biotechnology Vol.19 No.3

Experimental study on cold-formed lipped channel stub columns reinforced by steel bars or steel strips

Jian-Feng Chen,Ming-Qi Chen,Yong-Kang Shen,Jian-Hua Shao,Xin-Xin Yang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.3

In this paper, the axial compressive properties of cold-formed steel lipped channel stub columns strengthened by rebars or steel strips are experimentally studied. The experiment included two sections. A kind of columns with local buckling is reinforced longitudinally by steel strips at the web. The other is the columns with distorted buckling, which is reinforced longitudinally by steel bars at the curling edge. The failure mode, deformation characteristics, ultimate bearing capacity and load displacement curve of the specimen are obtained through the experiment. On the basis of the experiment, the calculation results of theoretical axial bearing capacity of cold-formed steel lipped channel stub columns in Chinese, North American and Australian code are compared and analyzed. Research indicates: First, the cold-formed steel lipped channel stub columns strengthened by steel bars or steel strips can effectively improve the compressive bearing capacity of the specimen. Secondly, when the initial stress ratio of specimen is less than 0.3, the reinforcement effect is ideal. Thirdly, the three standards don’t stipulate the calculation of theoretical bearing capacity of the specimen strengthened after loading, so there is a large deviation between the theoretical calculation value and the test value.

Use of an Artificial Neural Network to Construct a Model of Predicting Deep Fungal Infection in Lung Cancer Patients

Chen, Jian,Chen, Jie,Ding, Hong-Yan,Pan, Qin-Shi,Hong, Wan-Dong,Xu, Gang,Yu, Fang-You,Wang, Yu-Min Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.12

Background: The statistical methods to analyze and predict the related dangerous factors of deep fungal infection in lung cancer patients were several, such as logic regression analysis, meta-analysis, multivariate Cox proportional hazards model analysis, retrospective analysis, and so on, but the results are inconsistent. Materials and Methods: A total of 696 patients with lung cancer were enrolled. The factors were compared employing Student's t-test or the Mann-Whitney test or the Chi-square test and variables that were significantly related to the presence of deep fungal infection selected as candidates for input into the final artificial neural network analysis (ANN) model. The receiver operating characteristic (ROC) and area under curve (AUC) were used to evaluate the performance of the artificial neural network (ANN) model and logistic regression (LR) model. Results: The prevalence of deep fungal infection from lung cancer in this entire study population was 32.04%(223/696), deep fungal infections occur in sputum specimens 44.05%(200/454). The ratio of candida albicans was 86.99% (194/223) in the total fungi. It was demonstrated that older (${\geq}65$ years), use of antibiotics, low serum albumin concentrations (${\leq}37.18g/L$), radiotherapy, surgery, low hemoglobin hyperlipidemia (${\leq}93.67g/L$), long time of hospitalization (${\geq}14$days) were apt to deep fungal infection and the ANN model consisted of the seven factors. The AUC of ANN model($0.829{\pm}0.019$)was higher than that of LR model ($0.756{\pm}0.021$). Conclusions: The artificial neural network model with variables consisting of age, use of antibiotics, serum albumin concentrations, received radiotherapy, received surgery, hemoglobin, time of hospitalization should be useful for predicting the deep fungal infection in lung cancer.

Accurate transfer of bimaxillary orthognathic surgical plans using computer-aided intraoperative navigation

Chen Chen,Ningning Sun,Chunmiao Jiang,Yanshan Liu,Jian Sun 대한치과교정학회 2021 대한치과교정학회지 Vol.51 No.5

Objective: To examine the accuracy of computer-aided intraoperative navigation (Ci-Navi) in bimaxillary orthognathic surgery by comparing preoperative planning and postoperative outcome. Methods: The study comprised 45 patients with congenital dentomaxillofacial deformities who were scheduled to undergo bimaxillary orthognathic surgery. Virtual bimaxillary orthognathic surgery was simulated using Mimics software. Intraoperatively, a Le Fort I osteotomy of the maxilla was performed using osteotomy guide plates. After the Le Fort I osteotomy and bilateral sagittal split ramus osteotomy of the mandible, the mobilized maxilla and the distal mandibular segment were fixed using an occlusal splint, forming the maxillomandibular complex (MMC). Realtime Ci-Navi was used to lead the MMC in the designated direction. Osteoplasty of the inferior border of the mandible was performed using Ci-Navi when facial symmetry and skeletal harmony were of concern. Linear and angular distinctions between preoperative planning and postoperative outcomes were calculated. Results: The mean linear difference was 0.79 mm (maxilla: 0.62 mm, mandible: 0.88 mm) and the overall mean angular difference was 1.20°. The observed difference in the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was < 1 mm in 40 cases. Conclusions: This study demonstrates the role of Ci-Navi in the accurate positioning of bone segments during bimaxillary orthognathic surgery. Ci-Navi was found to be a reliable method for the accurate transfer of the surgical plan during an operation.

Kinetics of Nitrogen Absorption in Molten AISI 316 Stainless Steel During Immersion Nitrogen Blowing

Chen Jian-Bin,Chen Qi-Zhong,Chen Zhao-Ping,Jiang Zhou-Hua,Huang Zong-Ze,Pan Jia-Qi 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.1

Nitrogen absorption in molten metal for stainless steel AISI316 has been investigated by immersion nitrogen blowing through an immersed alumina nozzle with an internal diameter of 3 mm. Based on these experimental data, some kinetic parameters of nitrogen absorption, such as reaction order, rate constant and apparent activation energy of nitrogen absorption reaction, have been obtained. Effect of stirring by immersion nitrogen blowing through an immersed alumina nozzle on nitrogen absorption reaction has been observed. Results show the following: (1) Nitrogen absorption reaction is the −1.5th order reaction. The rate constant N is of the order of 10−5wt%2.5·min −1. Nitrogen absorption reaction for AISI 316 has negative apparent activation energy of −92.40 kJ·mol −1. This indicates that the nitrogen absorption reaction has a complex and multistep reaction mechanism. (2) The rate of nitrogen absorption reaction in molten stainless steel is mixture control by the adsorption of monatomic nitrogen on the surface of molten stainless steel and mass transfer in molten metal. (3) A rate equation of nitrogen absorption reaction has been derived based on a mixed control mechanism by both the -1st order nitrogen absorption reaction and mass transfer in molten metal.

The Nature of Acid-Catalyzed Acetalization Reaction of 1,2-Propylene Glycol and Acetaldehyde

( Chen Cheng ),( Hui Chen ),( Xia Li ),( Jian Li Hu ),( Bao Chen Liang ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.4

We investigated catalytic activity of ion-exchange resins in acetalization of 1,2-propylene glycol with acetaldehyde. The impacts of reaction variables, such as temperature, reaction time, catalyst loading and feedstock composition, on the conversion of 1,2-propylene glycol were measured. The life of the catalyst was also studied. Furthermore, the reaction kinetics of 1,2-propylene glycol acetalization was studied. It was found that reaction rate followed the firstorder kinetics to acetaldehyde and 1,2-propylene glycol, respectively. Therefore, overall acetalization reaction should follow the second-order reaction kinetics, expressed as r=kC pile{nA#A} C pile{nB#B} =19.74 {-6650} over {T} C pile{1#A} C pile{1#B}.

Comparison Study of the Band-gap Structure of a 1D-Photonic Crystal by Using TMM and FDTD Analyses

Jian-Bo Chen,Yan Shen,Wei-Xi Zhou,Yu-Xiang Zheng,Hai-Bin Zhao,Liang-Yao Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.42

A variety of numerical methods has been developed to demonstrate the nature of photons propagating in an artificially-composed periodic structure. Differences will be generated by different kinds of numerical approaches. In this work, we carry out two types of numerical calculations, TMM (transfer matrix method) and FDTD (finite different time domain) calculations. In terms of the 1D-photonic crystal structures with two different structures, we illustrate the energy band spectra, and the results show dispersive characteristics for the optical transmission and reflection of the crystal material. Through a discussion of the mechanism, detailed comparison studies are preformed based on the different physical conditions. The results given in the work will help in better understanding the ways in which photons propagate in an artificially-composed periodic structure.

Analysis of Small Fragment Deletions of the APC gene in Chinese Patients with Familial Adenomatous Polyposis, a Precancerous Condition

Chen, Qing-Wei,Zhang, Xiao-Mei,Zhou, Jian-Nong,Zhou, Xin,Ma, Guo-Jian,Zhu, Ming,Zhang, Yuan-Ying,Yu, Jun,Feng, Ji-Feng,Chen, Sen-Qing Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.12

Background: : Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease mainly caused by mutations of the adenomatous polyposis coli (APC) gene with almost complete penetrance. These colorectal polyps are precancerous lesions that will inevitable develop into colorectal cancer at the median age of 40-year old if total proctocolectomy is not performed. So identification of APC germline mutations has great implications for genetic counseling and management of FAP patients. In this study, we screened APC germline mutations in Chinese FAP patients, in order to find novel mutations and the APC gene germline mutation characteristics of Chinese FAP patients. Materials and Methods: The FAP patients were diagnosed by clinical manifestations, family histories, endoscope and biopsy. Then patients peripheral blood samples were collected, afterwards, genomic DNA was extracted. The mutation analysis of the APC gene was conducted by direct polymerase chain reaction (PCR) sequencing for micromutations and multiplex ligation-dependent probe amplification (MLPA) for large duplications and/or deletions. Results: We found 6 micromutations out of 14 FAP pedigrees, while there were no large duplications and/or deletions found. These germline mutations are c.5432C>T(p. Ser1811Leu), two c.3926_3930delAAAAG (p.Glu1309AspfsX4), c.3921_3924delAAAA (p.Ile1307MetfsX13), c3184_3187delCAAA(p.Gln1061AspfsX59) and c4127_4126delAT (p.Tyr1376LysfsX9), respectively, and all deletion mutations resulted in a premature stop codon. At the same time, we found c.3921_3924delAAAA and two c.3926_3930delAAAAG are located in AAAAG short tandem repeats, c3184_3187delCAAA is located in the CAAA interrupted direct repeats, and c4127_4128 del AT is located in the 5'-CCTGAACA-3', 3'-ACAAGTCC-5 palindromes (inverted repeats) of the APC gene. Furthermore, deletion mutations are mostly located at condon 1309. Conclusions: Though there were no novel mutations found as the pathogenic gene of FAP in this study, we found nucleotide sequence containing short tandem repeats and palindromes (inverted repeats), especially the 5 bp base deletion at codon 1309, are mutations in high incidence area in APC gene,.