Structural Performance of Earthquake-damaged Beams in Fire

Bo Wen,Lu Zhang,Bo Wu,Ditao Niu 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.12

Post-Earthquake Fire (PEF) on frame structures usually leads to complicated and unpredictable thermal performance of damaged concrete members. In order to determine the structural performance of seismic-damaged Reinforced Concrete (RC) beams under PEF conditions, the RC frame structures are subjected to the shake table test. The test, used in conjunction with other existing seismic hazard data, demonstrates that the main geometric damage forms of RC beams after the earthquake are cracks and concrete spalling. Subsequently, calculating models of PEF RC beams are established in ABAQUS, and then the distribution of thermal field, hightemperature bearing capacity and reduction coefficient of seismic-damaged beams are proposed respectively. From experimental and numerical investigations, It can conclude that (a) the simplified numerical models are proven to accurately determine the fire performance of the damaged RC beams; (b) the thermal performance degradation caused by spalling is more severe than the degradation caused by cracking on PEF RC beams, which demonstrates that spalling takes a more important role than cracking; and (c) the prediction equation of the flexural bearing capacity reduction factor of PEF RC beams is feasible.

윌리엄 보웬(William M. Bowen) : 학제적 지역연구의 지평을 열다

윌리엄 보웬(William M. Bowen),권성문(Sung Moon Kwon) 국토연구원 2016 국토 : planning and policy Vol.421 No.-

Nonlinear fatigue life prediction models based on material damage state correction

Bowen Wang,Qiwen Xue 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.12

The determination of the interaction factor of adjacent loads under variable amplitude loading is difficult. In this paper, two new nonlinear accumulation damage models are proposed based on the material damage state. Besides considering loading sequence, load interference, and mean stress effect, the proposed models consider the effect of material damage state and then modify the key parameter δ by introducing the load cycle ratio and the amount of material memory degradation in order to express the damage state. Verifying by different materials' test data and comparing with the existing models shows the proposed models good predictive ability and reliability. Further, in this method, there are no new variables introduced, no complex nested calculations, and only one conventional parameter that is easy to obtain by experimental fitting. Furthermore, the proposed models are convenient for fatigue life prediction in practical engineering problems.

In-Situ Observation of Grain Refinement in the Simulated Heat-Affected Zone of High-Strength Low-Alloy Steel by Zr-Ti Combined Deoxidation

Bowen Zhou,Guangqiang Li,Xiangliang Wan,Yu Li,Kaiming Wu 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.2

The effect of Zr-Ti combined deoxidation on the grain refinement in the simulated coarse-grained heat-affected zone of a high-strength low-alloy steel was investigated by means of analytical characterization techniques such as in-situ microscopy, transmission electron microscopy, and electron backscattered diffraction analysis. Owing to the Zr-Ti combined deoxidation, a large amount of fine Zr-Ti oxide particles were formed in the steel and retarded the austenite grain growth during simulated welding thermal cycle. The austenite grains were small and uniform. The Mn can diffuse spontaneously from austenite to Zr-Ti oxide inclusion and MnS precipitated on ZrO2, which can form Mn depleted zone in the vicinity of inclusion. The acicular ferrite grains nucleated on intragranular Zr-Ti oxide inclusions in austenite grains grew in different directions and effectively divided the austenite grain into several finer and separate regions at intermediate temperature. The crystallographic grain size became small in the simulated coarse-grained heat-affected zone of Zr-Ti-killed steel due to the effective pinning effect by Zr-Ti oxide particles and acicular ferrite formation.

Preparation of new visible-light driven nanocomposite photocatalysts, X/NaTaO3/Er3+:YAlO3 (X = Ag, Au and Pt), for photocatalytic conversion of Cr(VI)

Bowen Li,Yidi Wang,Fangyuan Tian,Guanshu Li,Zhaohong Zhang,Jun Wang,Youtao Song 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

In order to expand the light response range of wide band-gap semiconductor photocatalyst (NaTaO3) for effective photocatalytic conversion of Cr(VI), an up-conversion luminescence agent (Er3+:YAlO3) is combined with NaTaO3 and a visible-light driven photocatalyst, NaTaO3/Er3+:YAlO3, is prepared. Moreover, several conduction band co-catalysts (Ag, Au and Pt) are deposited the surface of NaTaO3/Er3+: YAlO3, respectively, to facilitate the transfer rate of photo-generated electrons. X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) analyses are employed to confirm the morphology, microstructure and composition of the prepared photocatalysts. In addition, UV–vis diffuse reflectance spectra are determined to explore the visible-light absorption properties of Er3+:YAlO3, NaTaO3, NaTaO3/Er3+:YAlO3 and X/NaTaO3/Er3+:YAlO3 (X = Ag, Au and Pt). Photoluminescence (PL) spectra are used to estimate the recombination rate of electron–hole pairs. The effects of irradiation time, photosource kind, solution acidity and used times on the photocatalytic capabilities of NaTaO3/Er3+:YAlO3 and X/NaTaO3/Er3+:YAlO3 (X = Ag, Au and Pt) are investigated in detail. The results show that the uses of up-conversion luminescence agent (Er3+:YAlO3) and co-catalysts (Ag, Au and Pt) can promote NaTaO3 to utilize visible-light to carry out the photocatalytic conversion of Cr(VI). Particularly, the prepared Au/NaTaO3/Er3+:YAlO3 nanocomposite with 1.0 wt% Au and 0.3:1.0 molar ratio of Er3+:YAlO3 and NaTaO3 shows the highest photocatalytic activity in conversion of Cr(VI).

Circuit Model for the Effect of Nonradiative Recombination in a High-Speed Distributed-Feedback Laser

Bowen Nie,Zhijuan Chi,Qing-an Ding,Xiang Li,Changqing Liu,Xiaojuan Wang,Lijun Zhang,Juan Song,Chaofan Li 한국광학회 2020 Current Optics and Photonics Vol.4 No.5

Based on single-mode rate equations, we present an improved equivalent-circuit model for distributedfeedback (DFB) lasers that accounts for the effects of parasitic parameters and nonradiative recombination. This equivalent-circuit model is composed of a parasitic circuit, an electrical circuit, an optical circuit, and a phase circuit, modeling the circuit equations transformed from the rate equations. The validity of the proposed circuit model is verified by comparing simulation results to measured results in the literature. The results show that the slope efficiency and threshold current of the model are 0.22 W/A and 13 mA respectively. It is also shown that increasing bias current results in the increase of the relaxation-oscillation frequency. Moreover, we show that the larger the bias current, the lower the frequency chirp, increasing the possibility of extending the transmission distance of an optical-fiber communication system. The results indicate that the proposed circuit model can accurately predict a DFB laser’s static and dynamic characteristics.

Improvement anti-pollution properties of electrical insulator by using a functional film

Bowen SHAN,Won Seok CHOI,Hyunil KANG,Yeun-Ho JOUNG 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.8

A novel energy-based numerical method for solving planet load sharing model considering elastic ring gear

Bowen Wan,Xiaojun Zhou 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

Ring gear elasticity is seldom considered in the investigations of planet load sharing. To overcome this and give an accessible numerical algorithm for solving similar problems, this work proposes a rigid-flexible coupling load sharing model for spur planetary gears that combines a conventional load sharing submodel with a curved beam element submodel, where the minimum potential energy principle (MPEP) is adopted to iteratively find the status having the minimum total potential energy of the whole system as the final load sharing result. This model is first validated by comparing it with published literature, and then further analyzed through a series of parametric studies, which reveals the influences of single or combined factors on load sharing. Practical suggestions on the design and application of planetary gears are provided at the end.

Enforcement of opacity security properties for ship information system

Bowen Xing,Jin Dai,Sheng Liu 대한조선학회 2016 International Journal of Naval Architecture and Oc Vol.8 No.5

In this paper, we consider the cybersecurity issue of ship information system (SIS) from a new perspective which is called opacity. For a SIS, its confidential information (named as “secret”) may be leaked through the working behaviors of each Distributed Control Unit (DCU) from an outside observer called an “intruder” which is able to determine ship's mission state by detecting the source of each data flow from the corresponding DCUs in SIS. Therefore we proposed a dual layer mechanism to enforce opacity by activating non-essential DCU during secret mission. This mechanism is calculated by two types of insertion functions: Safety-assured insertion function ( fIS) and Admissibility-assured insertion function ( fIA). Due to different objectives, fIS is designed to confuse intruder by constructing a non-secret behaviors from a unsafe one, and the division of fIA is to polish the modified output behaviors back to normal. We define the property of “I2eEnforceability” that dual layer insertion functions has the ability to enforce opacity. By a given mission map of SIS and the marked secret missions, we propose an algorithm to select fIS and compute its matchable fIA and then the DCUs which should be activated to release non-essential data flow in each step is calculable.

Blood-Blister Aneurysms of the Internal Carotid Artery in Tibetan and Han Populations : A Retrospective Observational Study

Bowen Huang,Yanming Ren,Hao Liu,Anqi Xiao,Lunxin Liu,Hong Sun,Yi Liu,Hao Liu,Lu Ma,Chang-Wei Zhang,Chao-Hua Wang,Min He,Yuekang Zhang,Chao You,Jin Li 대한신경외과학회 2024 Journal of Korean neurosurgical society Vol.67 No.3

Objective : Blood-blister aneurysms (BBAs) of the internal carotid artery (ICA) are challenging lesions with high morbidity and mortality rates. Although research on BBAs is well documented in different populations, the study of BBAs in the Tibetan population is extremely rare. This study aimed to evaluate the characteristics of BBAs and analyze the treatment modalities and long-term outcomes in the Tibetan population in comparison with the Han population. Methods : The characteristics of patients with BBAs of the ICA from January 2009 to January 2021 at our institution were reviewed. The features of aneurysms, treatment modalities, complications, and follow-up outcomes were retrospectively analyzed. Results : A total of 130 patients (41 Tibetan and 89 Han patients) with BBAs of the ICA who underwent treatment were enrolled. Compared with the Han group, the Tibetan group significantly demonstrated a high ratio of BBAs among ICAs (8.6%, 41/477 vs. 1.6%, 89/5563; p<0.05), a high ratio of vasospasm (34.1%, 14/41 vs. 6.7%, 6/89; p=0.001), a high risk of ischemic events (43.9%, 18/41 vs. 22.5%, 20/89; p<0.05), and a low ratio of good outcomes (modified Rankin scale, 0–2) at the 1-year follow-up (51.2%, 21/41 vs. 74.2%, 66/89; p<0.05). The multivariate regression model showed that ischemic events significantly contributed to the prediction of outcomes at 1 year. Further analysis revealed that microsurgery and vasospasm were associated with ischemic events. Conclusion : In comparison with Han patients, the Tibetan population had a high ratio of BBA occurrence, a high incidence of ischemic events, and a high ratio of poor outcomes. The endovascular approach showed more benefits in BBA patients.