Vibration analysis on the rolling element bearing-rotor system of an air blower

Wu Hao,Zhou Qiong,Zhang Zhiming,An Qi 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3

Air blowers are widely used in industry. The vibration of the rolling bearing-rotor is a key factor in the blower’s performance because it significantly influences the security and working life of the whole system. In previous research on the vibration characteristics of the air blower, the supporting rolling element bearing was always simplified as a particle on a shaft with radial stiffness and damping coefficient. Such simplification neglects the effects of the bearing structure on the vibration performance of the rotor system. In this paper, a numerical model of the bending stiffness of the tapered roller bearing was established through mechanics and deformation analysis. On the base of the model, a new TMM (transfer matrix method) for bearing-rotor system was established; the new TMM considers the influences of the bearing structure on the vibration of the rotor system. Furthermore, modal analysis on an air blower rotor system was carried out by using the new TMM, and the mode shape, critical speed and unbalance response of the air blower system were obtained. The same blower rotor was also analyzed by FEM to verify the validation of the new TMM, showing that the new method proposed in this paper for vibration characteristics calculation of an air blower is credible.

Identification and characterization of a new agar-degrading strain with the novel properties of saccharides inhibition and nitrogen fixation

Hao Wu,Guiguang Chen,Yaxi Bian,Wei Zeng,Bihong Sun,Zhiqun Liang 한국미생물학회 2017 The journal of microbiology Vol.55 No.6

In this study, a new agar-degrading strain was isolated from soil with agar as a sole carbon source and energy. Based on its morphological, physiological, biochemical characterization and 16S rDNA sequence, the strain was identified as Strep-tomyces lavendulae UN-8. The extracellular agarase activity reached 0.03 U/ml after fermentation in shake flask (250 ml), which was close to other reported non-marine micro-organisms. Furthermore, it is interesting that the growth of UN-8 would be inhibited by glucose (40 g/L) and maltose (40 g/L) with the inhibitory rate of 100% and 70%, respec-tively. Besides, UN-8 could be grown on the solid medium without any nitrogen sources, then the possible nitrogen fix-ation gene nifU was cloned from its genomic DNA. The de-duced amino acid sequence of nifU has high similarity (98%) with nitrogen fixation protein NifU from Streptomyces sp. NRRL S-104 (KJY22454.1) and Streptomyces sp. NRRL F-4428 (KJK52526.1) based on NCBI blast. It is suggested that the nifU gene of UN-8 also encoded nitrogen fixation protein NifU. These results provided some new information for the further understanding of agar-degrading strain.

Improvement of bond strength and durability of concrete incorporating high volumes of class F fly ash

Wu, Chung-Hao,Chen, Chien-Jung,Lin, Yu-Feng,Lin, Shu-Ken Techno-Press 2021 Advances in concrete construction Vol.12 No.5

This study experimentally investigated the improvement of bond strength and durability of concrete containing high volume fly ash. Concrete mixtures made with 0%, 25% and 60% replacement of cement with class F fly ash were prepared. Water-binder ratios ranged from 0.28 to 0.72. The compressive, flexural and pullout bond strength, the resistance to chloride-ion penetration, and the water permeability of concrete were measured and presented. Test results indicate that except for the concretes at early ages, the mechanical properties, bond strength, and the durability-related chloride-ion permeability and water permeability of concrete containing high volume (60% cement replacement) fly ash were obviously superior to the concrete without fly ash at later ages of beyond 56 days. The enhanced bond strength for the high volume fly-ash concrete either with or without steel confinement is a significant finding which might be valuable for the structural application.

One-pot synthesis of silica-gel-based adsorbent with Schiff base group for the recovery of palladium ions from simulated high-level liquid waste

Wu Hao,Kim Seong-Yun,Ito Tatsuya,Miwa Misako,Matsuyama Shigeo 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

A simple solvothermal reaction was used to prepare a 3-aminopropyl-functionalized silica-gel-based adsorbent for adsorbing Pd(II) from the nitric acid solution. Scanning electron microscopy, fourier transform infrared spectroscopy, and thermogravimetry analysis were performed on the as-synthesized adsorbent to demonstrate the successful introduction of Schiff base groups. Batch experiments were used to investigate the effects of contact time, nitric acid concentration, solution temperature, and adsorption capacity. It is worth noting that the prepared adsorbent exhibited a higher affinity toward Pd(II) with the uptake approximately 100% even in a 2 M HNO3 solution. At an equilibrium time of 5 h, the maximum adsorption capacity of Pd(II) was estimated to be 0.452 mmol/g. The adsorbed Pd(II) could be completely eluted by dissolving 0.2 M thiourea solution in 0.1 M HNO3. Using a combination of particle-induced Xray emission analysis and an X-ray photoelectron spectrometer, the adsorbed Pd was found to be uniformly distributed on the surface of the prepared adsorbent and the existing species were Pd(II) and zero-valent Pd(0). Due to the desirable performances, facile preparation method, and abundant raw material source, the prepared adsorbent demonstrated a high application potential in the recovery of Pd(II) from simulated high-level liquid waste treatment

Recovery of cesium ions from seawater using a porous silica-based ionic liquid impregnated adsorbent

Hao Wu,Tatsuya Kudo,Seong-Yun Kim,Misako Miwa,Shigeo Matsuyama 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5

A porous silica-based adsorbent was prepared by impregnating the pores of a silica support with theextractant 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) and anadditive agent 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C2mim þ NTf2) as thematerials to remove cesium(I) (Csþ) ions from seawater. The as-prepared adsorbent showed excellentadsorption performance toward Csþ ions, with adsorption equilibrium reached within 2 h and anadsorption amount of 0.196 mmol/g observed. The solution pH, temperature, and the presence ofcoexisting metal ions were found to have almost no effect on Csþ adsorption. The adsorption mechanismwas considered to proceed via ion exchange between Csþ and C2mimþ. In addition, the particle-inducedX-ray emission analysis results further clarified that the adsorbed Csþ ion species on the adsorbent wasin the form of both CsCl and CsBr

Carbon Emission Early Warning System Modeling and Simulation Study of Urban Regional Transportation

Hao Wu,Xianglian Zhao 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.8

Accurate assessment of carbon emission of urban regional transportation is the core of urban low-carbon traffic construction. Traditional carbon emission evaluation methods need a large number of samples and sample data of carbon emission of urban regional transportation is smaller, so the precision will be lower if traditional methods are adopted. This paper proposes particle swarm optimization to optimize support vector machine carbon emission early warning system of urban regional transportation (PSO-SVM) and takes the advantage of small sample data modeling of support vector machine to improve the carbon emission evaluation accuracy of urban regional transportation. Furthermore, this paper takes carbon emission evaluation accuracy of urban regional transportation as modeling target, selects reasonable evaluation index, confirms carbon emission evaluation model structure of urban regional transportation and then optimizes support vector machine (SVM) by adopting particle swarm optimization (PSO) to establish evaluation model and conduct system simulation. Results show that PSO-SVM actually increases the assessment accuracy, having practical application value in urban traffic carbon emission management.

Prediction Simulation Study of Road Traffic Carbon Emission Based on Chaos Theory and Neural Network

Hao Wu,Xianglian Zhao 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.7

Study the road traffic carbon emission and accurately predict the problems, the road traffic carbon emission has the complex systems of chaos and nonlinearity, the traditional method ignores the chaos of the road traffic carbon emission change, and it is so difficult to precisely control the rules of the road traffic carbon emission change that the precision of the of traffic carbon emission prediction is lower. In this study, it proposes the road traffic carbon emission prediction model based on the chaos theory and neural network and improves the prediction precision of the road traffic carbon emission time sequence. First of all, it reconstructs the time sequence data of the road traffic carbon emission change through the space, and sorts out the chaos change rules hidden in the time sequence data and then uses the BP neural network to study and carry out the modeling of the time sequence data of the road traffic carbon emission, and optimize the neural network parameter in order to improve the prediction precision of the road traffic carbon emission time sequence. The simulation result shows that, Chao-BPNN has overcome the deficits of the traditional method and could precisely and comprehensively reflect the change rules of the road traffic carbon emission time sequence, and effectively improved the prediction precision of the road traffic carbon emission.

Inductive and combinatorial reasoning in international educational context: assessment, measurement invariance, and latent mean differences

Wu, Hao,Saleh, Andi Rahmat,Molnár, Gyöngyvér 서울대학교 교육연구소 2022 Asia Pacific Education Review Vol.23 No.2

Indonesian 15-year-old students’ educational achievement has proved to be significantly lower than the international average based on one of the most prominent international large-scale assessments, OECD PISA. This prompted our interest in Indonesian students’ cognitive development during secondary schooling in comparison with that of students who are more successful on the PISA scale. This study aims to describe the development of Indonesian students’ thinking skills, especially inductive and combinatorial reasoning, to map the influencing factors in the development of reasoning skills and make a cross-national comparison study with their Hungarian peers. The sample was drawn from 250 Indonesian and 864 Hungarian 8th and 11th graders. The reliabilities of the tests were acceptable, with Cronbach’s alpha varying between .70 and .86. Results mainly indicated that: (a) the measures of these two constructs were partially invariant across nationalities; (b) the Indonesian students’ reasoning skills did not sufficiently develop between the 8th and 11th grades; (c) the Indonesian students’ inductive and combinatorial reasoning achievement was significantly worse than that of the Hungarian students in 11th grade, but not in 8th grade; and (d) the students’ learning strategies proved to be predictive factors in students’ reasoning skills achievement in both Indonesian and Hungarian contexts, but the level of prediction varied. Overall, the results of the current study provide support for an understanding of Indonesian students’ cognitive development compared to an international benchmark. The findings have implications for revising educational methods in Indonesia and may form the basis for further studies.

Iron and Phosphorus speciation in Fe-conditioned membrane bioreactor activated sludge

Hao Wu,Atsushi Ikeda-Ohno,Yuan Wang,T. David Waite 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

Experimental study on the tension of cables and motion of tunnel element for an immersed tunnel element under wind, current and wave

Wu Hao,Rheem Chang-Kyu,Chen Wei,Xu Shuangxi,Wu Weiguo 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

The tension of cables and motion response significantly affect safety of an immersed tunnel element in the immersion process. To investigate those, a hydrodynamic scale-model test was carried out and the model experiments was conducted under wind, current and wave loads simultaneously. The immersion standby (the process that the position of the immersed tunnel element should be located before the immersion process) and immersion process conditions have been conducted and illustrated. At the immersion standby conditions, the maximum force of the cables and motion is much larger at the side of incoming wind, wave and current, the maximum force of Element-6 (6 cables directly tie on the element) is larger than for Pontoon-8 (8 cables tie on pontoon of the element), and the flexible connection can reduce the maximum force of the mooring cables and motion of element (i.e. sway is expecting to decrease approximate 40%). The maximum force of the mooring cables increases with the increase of current speed, wave height, and water depth. The motion of immersed tunnel element increases with increase of wave height and water depth, and the current speed had little effect on it. At the immersion process condition, the maximum force of the cables decrease with the increase of immersion depth, and dramatically increase with the increase of wave height (i.e. the tension of cable F4 of pontoons at wave height of 1.5 m (83.3t) is approximately four times that at wave height of 0.8 m). The current speed has no much effect on the maximum force of the cables. The weight has little effect on the maximum force of the mooring cables, and the maximum force of hoisting cables increase with the increase of weight. The maximum value of six-freedom motion amplitude of the immersed tunnel element decreases with the increase of immersion depth, increase with the increase of current speed and wave height (i.e. the roll motion at wave height of 1.5 m is two times that at wave height of 0.8 m). The weight has little effect on the maximum motion amplitude of the immersed tunnel element. The results are significant for the immersion safety of element in engineering practical construction process.