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TRANSVERSAL INERTIAL EFFECT ON RELAXATION/RETARDATION TIME OF CEMENT MORTAR UNDER HARMONIC WAVE

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Acta Mechanica Solida Sinica 2008年第1期21卷 44-50页

作者： Jue zhu Yonghui cao Jiankang Chen Mechanics and Materials Science Research Center Ningbo University Ningbo 315211 China

Under dynamic loading, the constitutive relation of the cement mortar will be significantly affected by the transversal inertial effect of specimens with large diameters. In this paper, one-dimensional theoretical analysis is carried out to determine the transversal inertial effect on the relaxation/retardation time of the cement mortar under the harmonic wave. Relaxation time or retardation time is obtained by means of the wave velocity, attenuation coefficient and the frequency of the harmonic wave. Thus, the transversal inertial effect on the relaxation time from Maxwell model, as well as on retardation time from Voigt model is analyzed. The results show that the transversal inertial effect may lead to the increase of the relaxation time, but induce the decrease of the retardation time. Those should be taken into account when eliminating the transversal inertial effect in applications.

关键词： cement mortar harmonic wave viscoelastic model relaxation/retardation time

MODELING AND CONTROLLING OF PARALLEL MANIPULATOR JOINT DRIVEN BY PNEUMATIC MUSCLES

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Chinese Journal of Mechanical Engineering 2005年第4期18卷 537-541页

作者： Tao Guoliang zhu Xiaocong cao Jian State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A parallel manipulator joint driven by three pneumatic muscles and its posture control strategy are presented. Based on geometric constraints and dynamics, a system model is developed through which some influences on dynamic response and open-loop gain are analyzed including the supply pressure, the initial pressure and the volume of pneumatic muscle. A sliding-mode controller with a nonlinear switching function is applied to control posture, which adopts the combination of a main method that separates control of each muscle and an auxiliary method that postures error evaluation of multiple muscles, especially adopting the segmented and intelligent adjustments of sliding-mode parameters to fit different expected postures and initial states. Experimental results show that this control strategy not only amounts to the steady-state error of 0. 1° without overshoot, but also achieves good trajectory tracking.

关键词： Pneumatic muscle Parallel manipulator joint Sliding-mode controller Posture control

A Novel Pulse Design Based on Hermite Functions for UWB Communications

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The Journal of China Universities of Posts and Telecommunications 2006年第1期13卷 49-52页

作者： JIANG Guang-xing zhu Hong-bo cao Wei Wireless Communication and Electromagnetic Compatibility Laboratory Nanjing University of Posts and Telecommunications Nanjing 210003 P.R. China

This paper presents the design of a class of pulses that are based on Hermite functions for ultra-wideband communication systems. The presented class of pulses can not only meet the power spectral emission constraints of federal communications commission, but also have a short duration for multiple accesses. This paper gives closed form expressions of auto-and cross-correlation functions of the proposed pulses, which can be used to evaluate the performance of the correlator receiver. Furthermore, the paper investigates, under various channel conditions, the spectrum characteristic and the bit error rate of the pulses＇ wave forms. The investigation conditions include additive white Gaussian noise channels, multipleaccess interference channels, and fading multipath channels. Our results indicate that our systematic algorithm is flexible for designing ultra-wideband pulses that conform to spectral emission constraints and offer good bit error rate performance.

关键词： pulse design UWB Hermite functions multiple access multipath

INFLUENCE OF ALCOHOL-BASED NONSOLVENTS ON THE FORMATION AND MORPHOLOGY OF PVDF MEMBRANES IN PHASE INVERSION PROCESS

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Chinese Journal of Polymer Science 2006年第3期24卷 281-289页

作者： Dan-ying Zuo Bao-ku zhu Jian-hua cao 徐又一 Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China

Through the preparation of PVDF membranes using various nonsolvent coagulation baths following the phase inversion process, the influence of alcohol-based nonsolvents on the formation and structure of PVDF membranes were investigated. The light scattering and light transmission measurements were used to characterize the equilibrium phase diagram and the gelation speed, respectively. The locations of the crystallization-induced gelation boundaries for various systems and precipitation processes were explained from the corresponding thermodynamic and kinetic parameters. It was found that the better affinity between alcohol-based nonsolvents and DMAc solvent caused the gelation boundaries further away from the PVDF-DMAc axis with the coagulation bath varying from water, methanol, ethanol to iso-propanol. Due to the lower exchange rate of DMAc and alcohols, the delayed demixing took place for the membrane-forming using alcohols as baths, and the delayed time became longer when the coagulation bath was changed from methanol, ethanol to iso-propanol. The characterization results of membranes indicate that the influence of nonsolvents on the phase diagram and the precipitation process are in agreement with those on the membrane morphology. The better thermodynamic stability and a low exchange diffusion rate of PVDF/DMAc/alcohols favor the liquid-solid phase separation in gelation process, and therefore yield the membranes with a porous upper surface, a particular bottom surface and symmetrical structure.

关键词： Poly(vinylidene fluoride) membrane Kinetic diffusion Thermodynamic phase diagram Immersion precipitation Alcohol-based coagulation bath.

Learning Activity Sequencing in Personalized Education System

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Wuhan University Journal of Natural Sciences 2008年第4期13卷 461-465页

作者： zhu Fan cao Jiaheng School of Computer Wuhan University Wuhan 430072Hubei China

Personalized education provides an open learning environment which enriches the advanced technologies to establish a paradigm shift, active and dynamic teaching and learning patterns. E-learning has a various established approaches to the creation and sequencing of content-based, single learner, and self-paced learning objects. However, there is little understanding of how to create sequences of learning activities which involve groups of learners interacting within a structured set of collaborative environments. In this paper, we present an approach for learning activity sequencing based on ontology and activity graph in personalized education system. Modeling and management of learning activity and learner are depicted, and an algorithm is proposed to realize learning activity sequencing and learner ontology dynamically updating.

关键词： learning activity sequencing ontology personalized education

Field observation of wave overtopping at sea dike using shore-based video images

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Journal of Hydrodynamics 2021年第4期33卷 657-672页

作者： Shan-hang Chi Chi Zhang Ti-ti Sui zhu-bin cao Jin-hai Zheng Jiang-shan Fan State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing210098China Key Laboratory of Ministry of Education for Coastal Disaster and Protection Hohai UniversityNanjing210098China College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing210098China Rizhao Port Group Co. Ltd.Rizhao276826China

Wave overtopping at a sea dike was observed using video images during a storm in July 2018 at Rizhao Coast,China.A shore-based video monitoring system was mounted to collect coastal images with a sample frequency of 1 Hz in the beginning 10 min of each hour during daylight.A method to extract the frequency,location,width and duration of individual overtopping events based on the shore-based video monitoring system was developed.A total of 6252 individual overtopping events were detected over a 360m long sea dike during the storm of 10 h in a safe and labor-saving way,enabling a detailed analysis of the temporal and spatial variation of wave *** temporal variation of overtopping duration,frequency and volume is basically in sync with the change of tidal level(R=0.87,0.82 and 0.76,respectively).The increase of wave height increases the overtopping frequency *** found a high correlation between the hourly observed data and the predicted results of two commonly used *** the previous field measurements of overtopping that were limited in a single location,significant spatial variation of overtopping in the alongshore direction is *** overtopping volume varies with a factor of 6 within the range of several wave *** is further revealed that the spatial variation of overtopping is highly correlated with the alongshore variation of surf zone width with a correlation coefficient of *** present study suggests the feasibility of shore-based video monitoring technique to capture the main features of wave overtopping at coastal dikes,providing new possibilities to monitor wave overtopping in the field and to improve prediction tools.

关键词： Wave overtopping coastal video monitoring field measurement temporal and spatial variations storm events

Synergistic BrΦnsted/Lewis acid catalyzed atroposelective synthesis of aryl-β-naphthol

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Chinese Chemical Letters 2025年第1期36卷 293-298页

作者： Jiajun Lu Zhehui Liao Tongxiang cao Shifa zhu Key Laboratory of Functional Molecular Engineering of Guang-dong Province School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou 510640China School of Chemistry and Chemical Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071China

Axially chiral binaphthol have achieved great success in asymmetric *** toα-binaphthol,axially chiral aryl-β-naphthol are far less ***,we report a method of asymmetric catalysis to constructβ-naphthol with up to 99%yield,95.5:4.5 enantiomeric ratio,using alkynyl esters as precursors and chiral phosphonic acid(CPA)/Lewis acid as *** steps involve oxygen transfer and de novo arene formation to set up the chiral ***,this methodology provides a versatile platform for structurally divergent synthesis of atroposelectiveβ-naphthol analogs,which are widely found in bioactive molecules and asymmetric catalysts.

关键词： Synergistic catalysis Atropisomerism Aryl-β-naphthol Enantioselectivity Tandem reaction

Research progress of lignin-derived materials in lithium/sodium ion batteries

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Green Energy & Environment 2025年第2期10卷 322-344页

作者： Jingke Zhang Hengxue Xiang Zhiwei cao Shichao Wang Meifang zhu Institute of Hybrid Materials National Center of International Research for Hybrid Materials TechnologyNational Base of International Science&Technology CooperationCollege of Materials Science and EngineeringQingdao UniversityQingdao266071China State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and EngineeringDonghua UniversityShanghai201620China

With the increase of energy consumption,the shortage of fossil resource,and the aggravation of environmental pollution,the development of cost-effective and environmental friendly bio-based energy storage devices has become an urgent *** the second most abundant natural polymer found in nature,lignin is mainly produced as the by-product of paper pulping and bio-refining *** possesses several inherent advantages,such as low-cost,high carbon content,abundant functional groups,and bio-renewable,making it an attractive candidate for the rechargeable battery ***,there has been a surge of research interest in utilizing lignin or lignin-based carbon materials as the components of lithium-ion(LIBs)or sodium-ion batteries(SIBs),including the electrode,binder,separator,and *** review provides a comprehensive overview on the research progress of lignin-derived materials used in LIBs/SIBs,especially the application of lignin-based carbons as the anodes of LIBs/*** preparation methods and properties of lignin-derived materials with different dimensions are systemically discussed,which emphasizes on the relationship between the chemical/physical structures of lignin-derived materials and the performances of LIBs/*** current challenges and future prospects of lignin-derived materials in energy storage devices are also proposed.

关键词： Lignin-based carbons Lithium battery Sodium battery Chemical structure evolution

Biosorption effects of copper ions on Candida utilis under negative pressure cavitation

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Journal of Environmental Sciences 2006年第6期18卷 1254-1259页

作者： ZU Yuan-gang ZHAO Xiu-hua HU Mao-sheng REN Yuan XIAO Peng zhu Lei cao Yu-jie ZHANG Yao Key Laboratory of Forest Plant Ecology Northeast Forestry University Ministry of Education Harbin 150040 China

Under the optimal condition of copper ions adsorption on yeast,we found some different effects among static adsorption, shaking adsorption and negative pressure cavitation adsorption, and the methods of yeast with different pretreatments also affect adsorption of copper ions. At the same time, the change of intercellular pH before and after adsorption of copper with BCECF was studied. The copper distribution was located by using PhenGreen （dipotassium salt and diacetate）, and the surface of yeast was observed by an atomic force microscope. The results showed that negative pressure cavitation can improve bioadsorption capacity of copper ions on yeast. However, the yeasts＇ pretreatment has a higher effect on bioadsorption. It indicates that heavy metal bioadsorption on yeast has much relation with its cellular molecule basis. With the adsorping, the intercellular pH of yeast increased gradually and changed from acidity to alkalescence. These results may suggest that negative pressure cavitation can compel heavy metals to transfer from the cell surface into inside cell and make the surface of yeast coarse.

关键词： negative pressure cavitation Candida utilis biosorption copper ion adsorption mechanism