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Preparation of ABA triblock copolymer assemblies through “one-pot” RAFT PISA

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Chinese Chemical Letters 2020年第6期31卷 1660-1664页

作者： Yanling cao Yan shi Xiaohui Wu Liqun Zhang Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China

Poly(N,N-dimethyl acrylamide)-block-poly(styrene)-block-poly(N,N-dimethyl acrylamide)(PDMAc-bPSt-b-PDMAc)amphiphilic triblock copolymer micro/nano-objects were synthesized through reversible addition-fragmentation chain transfer(RAFT)dispersion polymerization of St mediated with poly(N,Ndimethyl acrylamide)trithiocarbonate(PDMAc-TTC-PDMAc)bi-functional macromolecular RAFT *** is found that the morphology of the PDMAc-b-PSt-b-PDMAc copolymer micro/nano-objects like spheres,vesicles and vesicle with hexagonally packed hollow hoops(HHHs)wall can be tuned by changing the solvent *** addition,vesicles with two sizes(600 nm,264 nm)and vesicles with HHHs features were also synthesized in high solid content systems(30 wt%and 40 wt%,respectively).Besides,as compared with typical AB diblock copolymers(A is the solvophilic,stabilizer block,and B is the solvophobic block),ABA triblock copolymers tend to form higher order morphologies,such as vesicles,under similar *** finding of this study provides a new and robust approach to prepare block copolymer vesicles and other higher order micelles with special structure via PISA.

关键词： Reversible addition-fragmentation chain transfer Polymerization Polymerization induced self-assembly Triblock copolymer Dispersion polymerization Block copolymer micelles

Study on Hydraulic System Efficiency of Heaving-Buoy Wave Energy Converter

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Journal of Ocean University of China 2018年第5期17卷 1044-1052页

作者： shi Hongda ZHAO Chenyu LIU Zhen cao Feifei College of Engineering Ocean University of ChinaQingdao 266100China Shandong Provincial Key Laboratory of Ocean Engineering Qingdao 266100China

The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation and model testing of the combined heaving-buoy *** derive a new governing equation that includes nonlinear hydraulic resistance in the power take-off(PTO).We conducted a physical model experiment based on a 100-kW prototype and applied a hydraulic system with an energy *** model test results reveal an important parameter related to efficiency with respect to nonlinear hydraulic *** also studied the relationship between the efficiency and the initial ***,based on our numerical simulation results,we discuss the effect on efficiency of the gas content of the hydraulic fluid and ways to reduce its impact.

关键词： hydraulic system PTO nonlinear hydraulic resistance efficiency gas content

The Research on Typhoon Wave Spectrum in Northwestern South China Sea

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Journal of Ocean University of China 2017年第1期16卷 8-14页

作者： shi Hongyuan cao Xuefeng WEN Xianhua shi Maochong ZHAO Dongliang GUO Peifang Physical Oceanography Laboratory Ocean University of ChinaQingdao 266100P.R.China Centre for Ports and Coastal Disaster Mitigation Ludong UniversityYantai 264025P.R.China Tianjin Research Institute of Water Transport Engineering of Ministry of Transport Tianjin 300456P.R.China

Based upon the one-year wind wave measurement data, collected from the South China Sea(SCS) at coordinates 20? 36.298?N, 110?45.433?E. by Acoustic Wave And Current(AWAC), we analyzed the wave characteristics and concluded that the most common wave direction was E and the second most common direction was ENE,the mean and the maximum values of significant height was 1.2 m and 4.36 m, respectively. The mean period was 4.0 s. We also evaluated the wave spectrums under conditions existing in three typhoons: Rumbi, Jeti and Utor. We found that unimodal spectrums occurred more often than others, and the maximum spectrum peak was 30.7911 m2 s. The minimum peak frequency was 0.0625 Hz, and the mean peak frequency was 0.126 Hz. The wave period is important for the design of marine structures, especially the position of peak frequency had a great influence on the stress calculation. Spectral analysis showed that the values of peak frequency distributed between 0.063 Hz and 0.217 Hz, with the mean value 0.114 Hz. We fit the normalized spectrum with 6 theoretical spectral models, out of which, the Wen spectrum, JONSWAP spectrum and Wallops spectrum were proved to give the best fit. What distinguished the Wen Spectrum from the rest was that it does not rely on the measured spectrum for parameter estimation. Hence, we recommend that the Wen spectrum should be widely used in marine construction.

关键词： typhoon wave wave spectrum theoretical wave spectrum

A needle tip CCEA microfluidic device based on enhanced Dean flow for cell washing

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Microsystems & Nanoengineering 2021年第5期7卷 105-117页

作者： Xin shi Wei Tan Yuwen Lu Wenfeng cao Guorui Zhu School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China Tianjin Tumor Hospital Tianjin Medical UniversityTianjin 300070China

Particle/cell washing is an essential technique in biological and clinical ***,we propose a novel circular contraction-expansion array(CCEA)*** can be directly connected to a needle tip without connection *** small size and centrosymmetric structure are beneficial to low sample consumption,high connection stability,and a wide application *** fluid dynamics(CFD)simulation results show that the CCEA structure can produce a stronger Dean flow and lead to faster particle/cell focusing than the circle structure and CEA structure with the same ***,an optimal flow rate ratio of 1:3 and an optimal total flow rate of 120μL/min were found to ensure a stable fluid *** these conditions,rapid focusing of 10-20μm particles with high efficiencies was *** with a normal CEA device using tubes,the particle loss rate could be reduced from 64 to 7%when washing 500μL of a rare *** suspensions with concentrations from 3×10^(5)/mL to 1×10^(3)/mL were *** high cell collection efficiency(>85%for three cell lines)and stable waste removal efficiency(>80%)reflected the universality of the CCEA microfluidic *** the washing,the cell activities of H1299 cells and MCF-7 cells were calculated to be 93.8 and 97.5%,*** needle-tip CCEA microfluidic device showed potential in basic medical research and clinical diagnosis.

关键词： needle fluid flow

Working characteristics of a new ventilator with automatic secretion clearance function

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Science China(Technological Sciences) 2015年第6期58卷 1046-1052页

作者： shi Yan NIU JingLong cao ZhiXin CAI MaoLin ZHU Jian School of Automation Science and Electrical Engineering Beihang University Beijing Chao Yang Hospital

Secretions in the airways of ventilated patients must be cleared efficiently and timely. A novel ventilator(SC ventilator) is proposed with an automatic secretion clearance function in order to provide a new approach. A mathematical model of a ventilation system with the SC ventilator is set up to optimize the SC ventilator. Based on the research, conclusion can be reached as follows. First, the experimental results and the mathematical model are proved to be authentic and reliable. Second, the secretion clearance efficiency of the SC ventilator may be higher than that of IL-IE device. Finally, increasing the inspiratory positive airway pressure or decreasing the expiatory positive airway pressure of the SC ventilator can improve the efficiency of the secretion clearance. This paper lays a foundation for the secretion clearance improvement of the SC ventilator.

关键词： mechanical ventilation pneumatic system secretion clearance modeling simulation experimental study

Aperiodically semi-intermittent-based fixed-time stabilization and synchronization of delayed discontinuous inertial neural networks

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Science China(Information Sciences) 2025年第1期 238-254页

作者： Guodong ZHANG Jinde cao School of Mathematics and Statistics South-Central Minzu University School of Mathematics Southeast University

This article concentrates on the fixed-time stabilization(FS) and fixed-time synchronization(FTS) of discontinuous inertial neural networks(DINNs) with distributed delays. Using mathematical induction to a new differential equality, a novel fixed-time stability lemma is constructed. Then, by designing an aperiodically semi-intermittent switching control and combining it with the theory of nonsmooth analysis, some novel criteria on the FS and FTS of DINNs are obtained. Unlike the methods used in most existing studies, the FS and FTS results are structured using the newly proposed fixed-time stability lemma and the nonreduced-order approach, resulting in broader practical applications and strengthening the scientific quality of the derived results. Lastly, numerical simulations and applications proffer the effectiveness of the established FS and FTS criteria.

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A novel method for vibration signal transmission and attenuation analysis in complex planetary gearboxes

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Science China(Technological Sciences) 2024年第9期67卷 2939-2953页

作者： WEI ChaoHu cao HongRui shi JiangHai YANG Yang DU MingGang National and Local Joint Engineering Research Center of Equipment Operation Safety and Intelligent Monitoring Xi’an Jiaotong UniversityXi’an 710049China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China China North Vehicle Research Institute Beijing 100072China

Planetary gearboxes play a crucial role in altering rotary speed and transmitting power in large machines like wind turbines and sophisticated vehicles. There are many nonlinear interfaces, such as splines, bearings, and gear pairs, in planetary gearboxes, and the resulting vibration signal transmission and attenuation mechanisms are still unknown. In this study, a novel method for quantitatively analyzing the transmission and attenuation of vibration signals is proposed. A multibody dynamic model of the planetary gearbox considering nonlinear gear meshing is presented and experimentally validated. To avoid the interference of foundation vibration on the transmission of the fault signal, the fault impact factor(FIF) is used to describe the intensity of the failure, which aligns well with the experimental signals. Based on the FIF, the vibration signal attenuation of nonlinear interfaces such as splines, bearings, and gear meshing interfaces is quantitatively evaluated. To clarify the transfer paths of fault vibration signals inside the gearbox, the transfer path area method(TPAM) based on FIF is proposed. According to the simulated results,the primary transfer paths of fault vibration signals within the gearbox have been identified, which is of great help in understanding the transmission and attenuation of vibration signals in planetary gearboxes.

关键词： planetary gearbox nonlinear interface fault mechanism vibration transmission vibration attenuation

A novel tunnel waterproof-drainage system based on double-bonded waterproofing materials and its seepage characteristics

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Frontiers of Structural and Civil Engineering 2024年第9期18卷 1321-1336页

作者： Xiaohe SUN Chenghua shi Guoqing XIAO Yangyang GE Chengyong cao School of Civil Engineering Central South UniversityChangsha 410075China PowerChina ZhongNan Engineering Corporation Limited Changsha 410014China State Key Laboratory of Special Functional Waterproof Materials Beijing Oriental Yuhong Waterproof Technology Co.Ltd.Beijing 101111China College of Civil and Transportation Engineering Shenzhen UniversityShenzhen 518060China

Double-bonded spray membrane waterproofing materials have excellent waterproofing performance and can improve the load-bearing capacity of tunnel linings,leading to an increasing global ***,due to the double-bonded capability of spray membrane materials,traditional interlayer drainage methods cannot be *** limitation makes it difficult to use them in drainage-type tunnels,significantly restricting their range of *** this regard,a novel tunnel waterproof-drainage system based on double-bonded spray membrane materials was proposed in this *** proposed drainage system primarily comprises upper drainage sheets and bottom drainage blind pipes,both located in the tunnel circumferential direction,as well as longitudinal drainage pipes within the ***,numerical calculation methods are employed to analyze the seepage characteristics of this system,revealing the water pressure distribution around the *** results indicate that in the novel waterproof-drainage system,the water pressure in the secondary lining exhibits a“mushroom-shaped”distribution in the circumferential direction,while the water pressure in the longitudinal direction exhibits a“wave-like”***,comparative results with other waterproof-drainage systems indicate that under typical working conditions with a water head of 160 m and a rock permeability coefficient of 10^(−6)m/s,the maximum water pressure in the secondary lining of the novel waterproof-drainage system is 0.6 *** represents a significant reduction compared to fully encapsulated waterproofing and traditional drainage systems,which respectively reduce the water pressure by 65%and 30%.The applicability analysis of the double-bonded waterproofing and drainage system reveals that it can reduce at least 40%of the static water pressure in any groundwater *** novel drainage system provides a valuable reference for the application of double-bonded spray membr

关键词： tunnel drainage spray-applied waterproofing membrane numerical simulation water pressure

Stable metal-organic frameworks with high catalytic performance in the cycloaddition of CO_2 with aziridines

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Science China Chemistry 2019年第5期62卷 622-628页

作者： Xiao-Min Kang Ying shi Chun-Shuai cao Bin Zhao College of Chemistry and Key Laboratory of Advanced Energy Material Chemistry Nankai University

Based on the mixed ligands XN(4′-(4-pyridine)4,2′:2′,4′′-terpyridine) and isophthalic acid(IPA), three new metal-organic frameworks(MOFs) {[M_2(XN)_2(IPA)_2]·2 H_2O}_n(M=Co(1), Mn(2), Ni(3)) were assembled and structurally characterized,presenting 3 D pillar-chain feature structures. Stability measurements demonstrate that these compounds possess high thermostability and can endure different organic solvents as well as various acid/base solutions with pH range of 1 to 14. Importantly,compounds 1–3 can serve as high-efficiency catalysts for the transformation of CO_2 and aziridines to form high-value oxazolidinones under mild conditions, exhibiting excellent cyclicity at least five times.

关键词： MOFs stability catalysis oxazolidinones CO2 conversion