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.

Triple versus dual antiplatelet therapy in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Chen, Kang-Yin,Rha, Seung-Woon,Li, Yong-Jian,Poddar, Kanhaiya L,Jin, Zhe,Minami, Yoshiyasu,Wang, Lin,Kim, Eung Ju,Park, Chang Gyu,Seo, Hong Seog,Oh, Dong Joo,Jeong, Myung Ho,Ahn, Young Keun,Hong, Taek American Heart Association, etc.] 2009 CIRCULATION - Vol.119 No.25

<P>BACKGROUND: Whether triple antiplatelet therapy is superior or similar to dual antiplatelet therapy in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention in the era of drug-eluting stents remains unclear. METHODS AND RESULTS: A total of 4203 ST-segment elevation myocardial infarction patients who underwent primary percutaneous coronary intervention with drug-eluting stents were analyzed retrospectively in the Korean Acute Myocardial Infarction Registry (KAMIR). They received either dual (aspirin plus clopidogrel; dual group; n=2569) or triple (aspirin plus clopidogrel plus cilostazol; triple group; n=1634) antiplatelet therapy. The triple group received additional cilostazol at least for 1 month. Various major adverse cardiac events at 8 months were compared between these 2 groups. Compared with the dual group, the triple group had a similar incidence of major bleeding events but a significantly lower incidence of in-hospital mortality. Clinical outcomes at 8 months showed that the triple group had significantly lower incidences of cardiac death (adjusted odds ratio, 0.52; 95% confidence interval, 0.32 to 0.84; P=0.007), total death (adjusted odds ratio, 0.60; 95% confidence interval, 0.41 to 0.89; P=0.010), and total major adverse cardiac events (adjusted odds ratio, 0.74; 95% confidence interval, 0.58 to 0.95; P=0.019) than the dual group. Subgroup analysis showed that older (>65 years old), female, and diabetic patients got more benefits from triple antiplatelet therapy than their counterparts who received dual antiplatelet therapy. CONCLUSIONS: Triple antiplatelet therapy seems to be superior to dual antiplatelet therapy in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention with drug-eluting stents. These results may provide the rationale for the use of triple antiplatelet therapy in these patients.</P>

Influence of light intensity on the slope of a nonlinear magneto-optical rotation for a laser locked to the Cs Fg = 4 → Fe = 5 transition

Chen Yong-Jian,Muhammad Jehanzaib-Aslam,Zhao Yue,Kang Chong,Zhang Jun-Hai 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.12

Based on a laser locked to the cesium Fg = 4 → Fe = 5 closed transition, we present the results of an investigation of nonlinear magneto-optical rotation (NMOR) using an uncoated buffer-gas-free cesium cell at room temperature under a near zero magnetic field, which has a reversal rotation signal and optimum rotation slope of − 46 rad/mT. Meanwhile, a magnetometer which has a simple structure and is available for cardiac magnetic measurement is reported. The magnetometer has a sensitivity of 0.3 pT/Hz1/2, which is limited by the photon-shot noise. Using a model for the interactions of atoms and linearly polarized light with arbitrary intensity that we built, we analyze the influence of the laser intensity on the linear dichroism of polarized atoms and the slope of the NMOR. The result of our theoretical analysis agrees with the experimental data. We also demonstrate that the intensity relative to zero slope is much less than the saturation intensity of the transition, because the rotation derives from the superposition of alignment precessions of Fg = 4 → Fe = 4,5 transitions and because the Fe = 5 state has a greater gyromagnetic ratio and total quantum number than Fg = 4 state does.

Peripheral arterial disease is associated with coronary artery spasm as assessed by an intracoronary acetylcholine provocation test

Chen, Kang-Yin,Rha, Seung-Woon,Li, Yong-Jian,Poddar, Kanhaiya L,Jin, Zhe,Minami, Yoshiyasu,Wang, Lin,Li, Guang-Ping,Saito, Shigeru,Park, Jae-Hyoung,Na, Jin-Oh,Choi, Cheol Ung,Lim, Hong-Euy,Kim, Jin-Wo Blackwell Publishing Ltd 2009 Clinical and Experimental Pharmacology & Physiolog Vol.36 No.11

<P>Summary</P><P>1. Both peripheral arterial disease (PAD) and coronary artery spasm (CAS) are associated with endothelial dysfunction. Thus, a higher incidence of CAS may be expected in patients with PAD. In the present study, we evaluated the incidence and characteristics of CAS in patients with PAD.</P><P>2. A total of 78 patients with PAD and 241 age- and gender-matched patients without PAD who had chest pain with normal coronary appearance on coronary angiograms underwent intracoronary acetylcholine (ACh) provocation test. Acetylcholine was injected into the left coronary artery in incremental doses of 20, 50 and 100 &mgr;g/min. Significant CAS was defined as a transient > 70% luminal narrowing with concurrent chest pain and/or ST segment changes.</P><P>3. Patients with PAD had a significantly higher incidence of ACh-induced significant CAS than those without PAD (60.3 vs 34.0%, respectively <I>P</I> < 0.001), as well as chest pain and ST segment changes during the ACh provocation test. Patients with PAD were more sensitive to lower doses of ACh and had a higher incidence of multivessel spasm than those without PAD. Multivariable logistic analysis showed that age, current smoking, PAD and myocardial bridge were independent predictors of ACh-induced significant CAS. Moreover, of these factors, PAD was the strongest independent predictor (odds ratio 4.25; confidence interval 1.33–13.54; <I>P</I> = 0.014).</P><P>4. In patients with chest pain, the presence of arterial disease at another site should still push the clinician towards treating the chest pain as angina, even if the coronary anatomy is normal on a coronary angiogram.</P>

Investigation on SCFs of concrete-filled circular chord and square braces K-joints under balanced axial loading

Yu Chen,Kang Hu,Jian Yang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.6

Most of the research work has been conducted on K-joints under static loading. Very limited information is available in consideration of fatigue strength of K-joints with concrete-filled chord. This paper aims to describe experimental and numerical investigations on stress concentration factors (SCFs) of concrete-filled circular chord and square braces K-joints under balanced axial loading. Experiment was conducted to study the hot spot stress distribution along the intersection of chord and braces in the two specimens with compacting concrete filled in the chord. The test results of stress distribution curves of two specimens were reported. SCFs of concrete-filled circular chord and square braces K-joints were lower than those of corresponding hollow circular chord and square brace K-joints. The corresponding finite element analysis was also conducted to simulate stress distribution along the brace and chord intersection region of joints. It was achieved that experimental and finite element analysis results had good agreement. Therefore, an extensive parametric study was carried out by using the calibrated finite element model to evaluate the effects of main geometric parameters and concrete strength on the behavior of concrete-filled circular chord and square braces K-joints under balanced axial loading. The SCFs at the hot spot locations obtained from ABAQUS were compared with those calculated by using design formula given in the CIDECT for hollow SHS-SHS K-joints. CIDECT Design Guide was generally quite conservative for predicting SCFs of braces and was dangerous for predicting SCFs of chord in concrete-filled circular chord and square braces K-joints. Finally SCF formulae were proposed for circular chord and square braces K-joints with concrete-filled in the chord under balanced axial loading. It is shown that the SCFs calculated from the proposed design equation are generally in agreement with the values derived from finite element analysis, which were proved to be reliable and accurate.

Spectrum Analysis with Adaptive Precision for Space Vector Pulse Width Modulation

Guoqiang Chen,Jianli Kang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.8

Aiming at the problem that the theoretical spectrum expression of the output voltage waveform in the space vector pulse width modulation strategy is often extremely complicated, most tedious and quite error-prone, the study develops a universal procedure and algorithm with adaptive precision to analyze the harmonic spectrum. The key steps and technique of the procedure and algorithm are given firstly. The algorithm steps include storing the switching states and the vector sequences, computing the basic space vector duration time, storing the duration time, sampling output voltage values and computing the spectrum using the fast Fourier transform algorithm. The sampling number doubles in each iteration for the next iteration. The adaptive precision is realized through controlling the amplitude or magnitude error between the current result and the previous result. The realization method and the key codes are presented secondly. Finally, three numerical experiments are presented to verify the developed algorithm, and the results verify its correctness, reliability and convenience.

Harmonic Analysis of A Random Zero Vector Distribution Space Vector Pulse Width Modulation

Guoqiang Chen,Jianli Kang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.6

Aiming at complicated characteristic analysis and implementation of the randomization space vector pulse width modulation (SVPWM) scheme, a new random zero-vector SVPWM scheme with a fixed randomization range is proposed. The fixed range is a linear function of the modulation index. Firstly, the principle of the new scheme is given. In addition, the implicit modulating voltages, the derivation procedure of the micro and macro harmonic distortion factor (HDF) are presented in detail, and the Monte Carlo method is proposed to efficiently analyze the HDF. Finally, the harmonic spectrum of the new scheme is analyzed compared with the commonly used symmetrical 7-segment SVPWM scheme through an example, and the result verifies its excellent performance on suppressing the cluster harmonic magnitude around the integer multiple switching frequency.

Development of a MATLAB Toolbox for 3-PRS Parallel Robot

Guoqiang Chen,Jianli Kang 보안공학연구지원센터 2014 International Journal of Hybrid Information Techno Vol.7 No.5

Fabricating Fe₃O₄ and Fe₃O₄&Fe Flower-like microspheres for Electromagnetic Wave Absorbing in C and X Bands

Na Chen,Dan Li,Xin‑Yi Wang,Zhen‑Jie Guan,Jian‑Tang Jiang,Kang‑Jun Wang 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.4

Magnetic composites have received increasing attention for electromagnetic wave absorption (EMA) applications. However,the practical EMA performance of the materials is severely hampered by mismatching impedance characteristics and finiteelectromagnetic attenuation capacity. Controlling the components and building the architecture fabrication is necessary tosolve these issues. Herein, a series of Fe3O4,Fe3O4&Fe and Fe microspheres with flower-like hierarchical structures wereconstructed through a solvothermal method followed by an annealed process. This hierarchical structure and the synergyeffect of dielectric dissipation and magnetic loss capacity offer Fe3O4a perfect impedance matching, providing an excellentEMA performance of an effective absorption bandwidth (EAB) of 4.0 GHz and a reflection loss (RL) of 67.9 dB. Meanwhile,the coordination of the hierarchical structures and the multiple components endow Fe3O4&Fe composites with an EAB aswide as 5.7 GHz (9.0–14.7 GHz) and a RL as strong as 78.7 dB at 1.88 mm, which covers 75% X and 45% Ku bands. Sucha remarkable lightweight and broad properties is due to the decent X band impedance matching and appropriate attenuationcapacity. Therefore, this work highlights the significant of regulating the hierarchical structure and components to enhancethe EMA performances.

Long-Term Oncologic Outcomes of Liver Resection for Hepatocellular Carcinoma in Adolescents and Young Adults: A Multicenter Study from A Hepatitis B Virus-Endemic Area

( Yong-kang Diao ),( Jun-wei Liu ),( Wan Yee Lau ),( Xin-ping Fan ),( Ting-hao Chen ),( Ya-hao Zhou ),( Wei-min Gu ),( Hong Wang ),( Jie Li ),( Ying-jian Liang ),( Tian Yang ) 대한간학회 2021 춘·추계 학술대회 (KASL) Vol.2021 No.1