Experimental Investigation on Damage Behavior of Polypropylene Fiber Reinforced Concrete under Compression

Lihua Xu,Biao Li,Xiaoxiao Ding,Yin Chi,Changning Li,Biao Huang,Yuchuan Shi 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.7

This paper presents an experimental investigation on the stress–strain behavior and the damage mechanism of polypropylene fiber reinforced concrete (PFRC) under monotonic and cyclic compression. Fifty-four specimens for different fiber volume fractions and aspect ratios were tested. Acoustic emission (AE) technique was used to monitor the damage progression. The damage mechanism of concrete was analyzed based on the AE parametric analysis. The results show that the incorporation of polypropylene fiber (PF) has a positive effect on the monotonic and cyclic behaviors of concrete, especially for the post-cracking branch. The toughness and ultimate strain are enhanced and the performance degradation in terms of elastic stiffness and strength is alleviated by the addition of PF. However, PF has little influences on the plastic strain, and the damage process of concrete is mainly driven by the envelope strain. The effect of fiber volume fraction on the cyclic behavior of concrete shows more pronounced than that of aspect ratio. In addition, it is found from AE results that the damage, closely related to AE events, has a quick evolution just after the peak stress, with the AE hits having a concentrated release. The total amount of AE hits increases with increasing fiber volume fraction due to fiber pullout and sliding, while the concrete with fiber aspect ratio of 280 reaches the largest amount. Meanwhile, as substantiated by AE, the failure of PFRC shows an obvious shear mode, with shear cracks dominating the damage progression. Finally, a damage elasto-plastic model is developed to predict the monotonic and cyclic responses of PFRC and the prediction yields a fairly close estimation with experimental results.

이산화탄소의 감압식 막탈거 시스템 설계

허려화(Lihua Xu),성호진(Hojin Sung),이진욱(Jinwook Lee),김형택(Hyung-Taek Kim) 한국에너지기후변화학회 2011 에너지기후변화학회지 Vol.6 No.2

The design program tool of carbon dioxide membrane vacuum stripper system for the MEA absorber was developed by PTFE plate-membrane contactor. And results of numerical simulation and experiments were compared at various stripping temperature and vacuum pressures. The stripping rate of carbon dioxide increased with increasing stripping temperature and vacuum pressure. The carbon dioxide stripping rate obtained from experiments substantially coincided with program simulation. By using the developed design program, we can design CO<SUB>2</SUB> membrane vacuum stripper system and derive optimal condition from various operating conditions.

폐기물 가스화 합성가스 이용 저압 메탄올 합성 공정 모사

허려화(Lihua Xu),임용택(Yongtaek Lim),구재회(Jaehoi Gu) 한국신재생에너지학회 2012 한국신재생에너지학회 학술대회논문집 Vol.2012 No.11

Positive Real Control for Uncertain 2-D Singular Roesser Models

Huiling Xu,Lihua Xie,Shenyuan Xu,Yun Zou 대한전기학회 2005 International Journal of Control, Automation, and Vol.3 No.2

宋代帝王與宰執的雅樂樂歌創作考述

徐利華(Xu Lihua) 동아인문학회 2013 동아인문학 Vol.24 No.-

Lots of The Song Dynasty Gagaku songs have become an important part of song poetry. However,most of his works are not mark the writer in the book of QuanSongShi. So, research the writer and creation time, has important significance to study the Song Dynasty Gagaku songs.the Emperor and Prime Minister constitutes an important part of the Song Dynasty Gagaku songs creation group, represent the voice from the power center. In this paper, the Song Dynasty emperor and kill the articulation with creative Gagaku songs: Emperor 5, a total of 85 councilors, 14, a total of 77, and one one research out of its creation time. Different and general poetry creation, music and songs not by literati improvisation, whether it is the creator of the status, or the content of the work style have strict requirements, hidden political metaphor. In the Song Dynasty, the emperor and prime minister to participate actively in the Gagaku songs creation, through the way of showing the court for the ritual attention, has greatly promoted the renaissance of Gagaku. Their work, like one"s resonant voice rings out, laid the entire song music songs creation.

Numerical Simulation of Seismic Waves with Peak Arrival Time and Amplitude-Frequency Correlation

Xu Han,Zhitao Wang,Ling-yun Peng,Jingyu Su,Lihua Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

To improve the accuracy with which the non-stationary intensity characteristics of artificial acceleration-time-history curves are determined, a method of adjusting the frequency correlation between the artificial peak arrival time and amplitude spectrum is proposed. A calculation method for determining the peak arrival time to reflect the physical meaning of the phase-differenc espectrum was first deduced. Subsequently, the amplitude-distribution characteristics corresponding to the peak arrival times for different durations of natural earthquakes were analyzed. In accordance with the distribution characteristics of the reference amplitude, the frequency distribution of the artificial peak arrival time was divided into four parts: the beginning, strong-earthquake, attenuation, and tail sections. By adjusting the arrival frequency of peak points for the different earthquake durations considered, the corresponding relationship between the artificial peak arrival time and amplitude spectrum was determined to be more consistent with the general law of natural earthquakes. The sample calculation described in this paper demonstrates that adjusting the frequency correspondence between the artificial peak arrival time and amplitude spectrum greatly improves the accuracy of the non-stationary intensity characteristics of artificial acceleration-time-history curves.

Highly stretchable polymer semiconductor films through the nanoconfinement effect

Xu, Jie,Wang, Sihong,Wang, Ging-Ji Nathan,Zhu, Chenxin,Luo, Shaochuan,Jin, Lihua,Gu, Xiaodan,Chen, Shucheng,Feig, Vivian R.,To, John W. F.,Rondeau-Gagné,, Simon,Park, Joonsuk,Schroeder, Bob C.,L American Association for the Advancement of Scienc 2017 Science Vol.355 No.6320

<P>Soft and conformable wearable electronics require stretchable semiconductors, but existing ones typically sacrifice charge transport mobility to achieve stretchability. We explore a concept based on the nanoconfinement of polymers to substantially improve the stretchability of polymer semiconductors, without affecting charge transport mobility. The increased polymer chain dynamics under nanoconfinement significantly reduces the modulus of the conjugated polymer and largely delays the onset of crack formation under strain. As a result, our fabricated semiconducting film can be stretched up to 100% strain without affecting mobility, retaining values comparable to that of amorphous silicon. The fully stretchable transistors exhibit high biaxial stretchability with minimal change in on current even when poked with a sharp object. We demonstrate a skinlike finger-wearable driver for a light-emitting diode.</P>

Dynamic CT Myocardial Perfusion Imaging in Patients without Obstructive Coronary Artery Disease: Quantification of Myocardial Blood Flow according to Varied Heart Rate Increments after Stress

Yu Lihua,Tao Xiaofeng,Dai Xu,Liu Ting,Zhang Jiayin 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.1

Objective: The present study aimed to investigate the association between myocardial blood flow (MBF) quantified by dynamic CT myocardial perfusion imaging (CT-MPI) and the increments in heart rate (HR) after stress in patients without obstructive coronary artery disease. Materials and Methods: We retrospectively included 204 subjects who underwent both dynamic CT-MPI and coronary CT angiography (CCTA). Patients with more than minimal coronary stenosis (diameter ≥ 25%), history of myocardial infarction/ revascularization, cardiomyopathy, and microvascular dysfunction were excluded. Global MBF at stress was measured using hybrid deconvolution and maximum slope model. Furthermore, the HR increments after stress were recorded. Results: The median radiation dose of dynamic CT-MPI plus CCTA was 5.5 (4.5–6.8) mSv. The median global MBF of all subjects was 156.4 (139.8–180.4) mL/100 mL/min. In subjects with HR increment between 10 to 19 beats per minute (bpm), the global MBF was significantly lower than that of subjects with increment between 20 to 29 bpm (153.3 mL/100 mL/min vs. 171.3 mL/100 mL/min, p = 0.027). This difference became insignificant when the HR increment further increased to ≥ 30 bpm. Conclusion: The global MBF value was associated with the extent of increase in HR after stress. Significantly higher global MBF was seen in subjects with HR increment of ≥ 20 bpm.

Polygonatum sibiricum component liquiritigenin restrains breast cancer cell invasion and migration by inhibiting HSP90 and chaperone-mediated autophagy

Suli Xu,Zhao Ma,Lihua Xing,Weiqing Cheng 대한생리학회-대한약리학회 2024 The Korean Journal of Physiology & Pharmacology Vol.28 No.4

Breast cancer (BC) is most commonly diagnosed worldwide. Liquiritigenin is a flavonoid found in various species of the Glycyrrhiza genus, showing anti–tumor activity. This article was to explore the influences of liquiritigenin on the biological behaviors of BC cells and its underlying mechanism. BC cells were treated with liquiritigenin alone or transfected with oe-HSP90 before liquiritigenin treatment. RTqPCR and Western blotting were employed to examine the levels of HSP90, Snail, Ecadherin, HSC70, and LAMP-2A. Cell viability, proliferation, migration, and invasion were evaluated by performing MTT, colony formation, scratch, and Transwell assays, respectively. Liquiritigenin treatment reduced HSP90 and Snail levels and enhanced E-cadherin expression as well as inhibiting the proliferation, migration, and invasion of BC cells. Moreover, liquiritigenin treatment decreased the expression of HSC70 and LAMP-2A, proteins related to chaperone-mediated autophagy (CMA). HSP90 overexpression promoted the CMA, invasion, and migration of BC cells under liquiritigenin treatment. Liquiritigenin inhibits HSP90-mediated CMA, thereby suppressing BC cell growth.

One-Stage Anterolateral Debridement, Bone Grafting, and Internal Fixation for Treating Lumbosacral Tuberculosis

Tao Zhang,Lihua Ma,Xu Lan,Ping Zhen,Shiyong Wang,Zhilin Li 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.2

Study Design: Retrospective case series. Purpose: To investigate the clinical efficacy and feasibility of one-stage anterolateral debridement, bone grafting, and internal fixation for treating lumbosacral tuberculosis. Overview of Literature: There has been no consensus regarding the optimal means of treating lumbosacral tuberculosis. The onestage anterolateral extraperitoneal approach for radical debridement, bone grafting, and internal fixation for treating lumbosacral tuberculosis is rare in literature. Methods: Twenty-one patients with lumbosacral tuberculosis were retrospectively analyzed. All patients underwent the surgery of anterolateral debridement after regularly antituberculous drugs therapy. We evaluated the erythrocyte sedimentation rate, C-reactive protein, radiography, computed tomography, magnetic resonance imaging, visual analogue score, and Oswestry disability index before and after surgery. Results: All patients completed a follow-up survey 9–48 months after surgery. All patients’ wounds healed well without chronic infection or sinus formation, and all patients with low-back pain reported relief after surgery. All cases had no tuberculosis recurrence. Solid bony fusion was achieved within 6–12 months. At final follow-up, evaluated the erythrocyte sedimentation rate decreased from 38.1±12.5 to 11.3±7.1 mm/hr, C-reactive protein decreased from 6.2±4.2 to 1.6±1.3 mg/dL, the visual analog scale score decreased from 4.6±1.1 to 1.4±1.0, the Oswestry disability index score decreased from 50.2%±11.9% to 13.0%±6.6%, and the lumbosacral angle increased from 20.0°±4.8° to 29.0°±3.9° (p <0.05). Conclusions: One-stage anterolateral debridement, bone grafting, and internal instrument fixation for treating lumbosacral tuberculosis is safe and effective.