检索结果-南通市图书馆

Spherical Polyelectrolyte Brush Nanoreactor:Preparation of Hollow TiO_(2) Nanospheres and Characterization by Small Angle X-Ray Scattering

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第9期42卷 1393-1400,I0009页

作者： Yu-hua Zhang Zi-Yu Zhang xin Liu En-Guang ma Jiang-Tao Guo Li Li Xu-Hong Guo State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai200237China Shandong Provincial Key Laboratory of Monocrystalline Silicon Semiconductor materials and Technology College of Chemistry and Chemical EngineeringDezhou UniversityDezhou253023China Institute of Bast Fiber Crops&Center of Southern Economic Crops Chinese Academy of Agricultural SciencesChangsha410205China

Titanium dioxide(TiO_(2))hollow nanoparticles present significant potential for photocatalytic applications while their straightforward preparation with precise structure control is still *** work reports the approach to preparing tunable hollow TiO_(2) nanospheres by utilization of spherical polyelectrolyte brushes(SPB)as nanoreactors and *** the preparation,the evolution of the structure was characterized by small angle X-ray scattering(SAXS),and in combination with dynamic light scattering and transmission electron *** formation of TiO_(2) shell within the brush(SPB@TiO_(2))is confirmed by the significant increase of the electron density,and its internal structure has been analyzed by fitting SAXS data,which can be influenced by Titanium precursors and ammonia *** calcining SPB@TiO_(2) in a muffle furnace,hollow TiO_(2) nanospheres are produced,and their transition to the anatase crystal form is triggered,as confirmed by X-ray diffraction *** the advantages of their hollow structure,these TiO_(2) nanospheres exhibit exceptional catalytic degradation efficiency of methylene blue(MB),tetracycline(TC),and 2,4-dichlorophenoxyacetic acid(2,4-D),and also demonstrate excellent recyclability.

关键词： Spherical polyelectrolyte brush Nanoreactor Hollow titanium dioxide X-ray scattering

Building trust networks in the absence of trust relations

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2017年第10期18卷 1591-1600页

作者： xin WANG Ying WANG Jian-hua GUO College of Computer Science and Technology Jilin University Changchun 130012 China School of Computer Technology and Engineering Changchun Institute of Technology Changchun 130012 China School of mathematics and Statistics Northeast Normal University Changchun 130024 China Key Laboratory of Symbolic Computation and Knowledge Engineering Ministry of Education Changchun 130012 China Guangxi Key Laboratory of Trusted Software Guilin University of Electronic Technology Guilin 541004 China

User-specified trust relations are often very sparse and dynamic, making them difficult to accurately predict from online social media. In addition, trust relations are usually unavailable for most social media *** issues pose a great challenge for predicting trust relations and further building trust networks. In this study,we investigate whether we can predict trust relations via a sparse learning model, and propose to build a trust network without trust relations using only pervasively available interaction data and homophily effect in an online world. In particular, we analyze the reliability of predicting trust relations by interaction behaviors, and provide a principled way to mathematically incorporate interaction behaviors and homophily effect in a novel framework,b Trust. Results of experiments on real-world datasets from Epinions and Ciao demonstrated the effectiveness of the proposed framework. Further experiments were conducted to understand the importance of interaction behaviors and homophily effect in building trust networks.

关键词： Trust network Sparse learning Homophily effect Interaction behaviors

Numerical Investigation of Run-ups on Cylinder in Steep Regular Wave

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2019年第5期33卷 601-607页

作者： FAN Xiang ZHANG Jing-xin LIU hua Department of Engineering Mechanics MOE Key Laboratory of Hydrodynamics School of NAOCE Shanghai Jiao Tong University

The run-up on offshore structures induced by the steep regular wave is a highly nonlinear flow with a free surface. This article focuses on the investigation of the steep regular wave run-up on a single vertical cylinder by solving the Navier-Stokes equations. A numerical wave tank is established based on the open-source package to simulate the wave scattering induced by a vertical cylinder. The VOF method is applied to capture the large deformation and breaking of the free surface. The numerical model is validated by experimental results. The relative wave run-ups on the front face and the back face along the centerline of a cylinder are analyzed. The changes of the relative run-ups with the wave steepness, the relative diameter and the relative depth are studied. It is found that the relative run-ups on the front face and the back face of the cylinder depend mainly on the wave steepness and the relative diameter, while the dependence on the relative depth is weak. The empirical formulae are proposed to calculate the relative run-ups in terms of the wave steepness of incident regular waves and the relative diameter of a cylinder.

关键词： steep regular wave vertical cylinder run-up empirical formula numerical experiments

Active disturbance rejection control for hydraulic width control system for rough mill

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第9期8卷 1429-1434页

作者： ZOU Jun FU xin YANG hua-yong Institute State Key Laboratoty of Fhtid Power Transmission and Control. Zhejiang University Hangzhou 310027 China

The highly nonlinear behavior of the system limits the performance of classical linear proportional and integral （PI） controllers used for hot rolling. An active disturbance rejection controller is proposed in this paper to deal with the nonlinear problem of hydraulic servo system in order to preserve last response and small overshoot of control system. The active disturbance rejection （ADR） controller is composed of nonlinear tracking differentiator （TD）, extended state observer （ESO） and nonlinear feedback （NF） law. An example of the hydraulic edger system case study is investigated to show the effectiveness and robustness of the proposed nonlinear controller, especially, in the circumstance of foreign disturbance and working condition variation, compared with classic PI controller.

关键词： Active disturbance rejection (ADR) Hydraulic servo system Width control Rough mill

Adjoint-Based Geometrically Constrained Aerodynamic Optimization of a Transonic Compressor Stage

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2019年第5期28卷 850-861页

作者： SU xinrong ma Can YUAN xin Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua University Beijing 100084 China Science and Technology on Thermal Energy and Power Laboratory Wuhan 430205 China

Efficient method to handle the geometric constraints in the optimization of turbomachinery blade profile is required. Without constraints on the blade thickness, optimal designs typically yield thinner blade to reduce the friction loss, however, at the risk of degraded strength and stiffness. This issue is seldom discussed and existing literature always treat the blade thickness constraint in an indirect manner. In this work, two different geometric constraints on the blade thickness are proposed and applied in the adjoint optimization: one is on the maximum blade thickness and the other is on the blade area. Methods to compute sensitivities of both constraints are proposed and they are integrated into an optimization system based on a finite volume code and a solver for the discrete adjoint equation. Adjoint optimization is conducted to minimize the entropy production in a transonic compressor stage. Results for the adjoint optimization without geometry constraint and two comparative cases are detailed. It is indicated that three cases yield similar performance improvement;however, if geometry constraints are properly handled, the optimal designs have almost the same maximum thickness as the original design, compared to a thinner blade profile with 14% reduction of maximum thickness in the case without geometry constraint. The cases considering geometry constraints also consume slightly reduced Central Processing Unit(CPU) cost. Result of this work verifies the effectiveness of the proposed method to treat geometric constraints in adjoint optimization.

关键词： aerodynamic optimization compressor stage discrete adjoint method geometric constraint

Interaction effect of micro-and macro-organic on the biogeochemical function of the sediment and aquatic interface

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2006年第3期18卷 468-474页

作者： XIAO Xiang LIAO Ling ZHANG xin-hua Guangzhou Environment Protection Bureau Guangzhou 510032 China Guangzhou Research Institute of Environmental Protection Guangzhou 510620 China South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China

Constructed stormwater infiltration basins have been broad applied in urban areas in terms of stormwater disposal and compensation of reduced groundwater recharge. However, stormwater derived from sediments accumulating in infiltration beds may act as a source of dissolved contaminants for groundwater. Concentrations of DO, NO3-N, NO2^--N, NH4^＋-N and PO4^3--P were monitored at multiple depth with time. The results showed that the occurrence of denitrificarion was restrained by sediments in term of no invertebrates. Under the conditions of invertebrates inoculated, the concentrations of DO, NO^3--N, NO2^＋-N, NH4^＋-N and PO4^3＋-P varied respectively with time and the occurrence of nitrification and mobilizing nitrate in the sediment. It is concluded that there exist the invertebrate activities such as building tubes and galleries and excreting faecal pellet which may increase water dispersion and enhance accessibility of nutrient, and stimulate microbial process effected in the sediment. Besides, the natural death and rot of worms were also found to be important factors of the invertebrate activities.

关键词： infiltration basins urban stormwater polluted sediments invertebrates effects

Simulation on a Car Interior Aerodynamic Noise Control Based on Statistical Energy Analysis

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第5期25卷 1016-1021页

作者： CHEN xin WANG Dengfeng ma Zhengdong State Key Laboratory of Automotive Simulation and Control Jilin University Changchun 130022 China Zhengjiang Geely Automobile Institute Co. Ltd. Hangzhou 311228 China College of Engineering University of Michigan Ann Arbor MI48109 USA

How to simulate interior aerodynamic noise accurately is an important question of a car interior noise reduction. The unsteady aerodynamic pressure on body surfaces is proved to be the key effect factor of car interior aerodynamic noise control in high frequency on high speed. In this paper, a detail statistical energy analysis （SEA） model is built. And the vibra-acoustic power inputs are loaded on the model for the valid result of car interior noise analysis. The model is the solid foundation for further optimization on car interior noise control. After the most sensitive subsystems for the power contribution to car interior noise are pointed by SEA comprehensive analysis, the sound pressure level of car interior aerodynamic noise can be reduced by improving their sound and damping characteristics. The further vehicle testing results show that it is available to improve the interior acoustic performance by using detailed SEA model, which comprised by more than 80 subsystems, with the unsteady aerodynamic pressure calculation on body surfaces and the materials improvement of sound/damping properties. It is able to acquire more than 2 dB reduction on the central frequency in the spectrum over 800 Hz. The proposed optimization method can be looked as a reference of car interior aerodynamic noise control by the detail SEA model integrated unsteady computational fluid dynamics （CFD） and sensitivity analysis of acoustic contribution.

关键词： car interior aerodynamic noise control computational fluid dynamics statistical energy analysis

A Middle Triassic stem-neopterygian fish from China sheds new light on the peltopleuriform phylogeny and internal fertilization

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2016年第22期61卷 1766-1774页

作者： Guang-Hui Xu xin-Ying ma Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences

Internal fertilization and viviparity are easily observed and well studied in living neopterygian fishes(14teleostean families), but they are difficult to identify in extinct taxa due to the limitation of the fossil record. The Peltopleuriformes from the Middle to Late Triassic of Europe and South China are a stem group of Neopterygii that may have first evolved internal fertilization and viviparity in this clade because they show a highly modified anal fin in presumed males resembling the intromittent organ in living viviparous teleosts. Until recently, Peltopleurus lissocephalus and P. rugosus from the Ladinian/Anisian boundary(*242 ma) of Monte San Giorgio area in Switzerland and Italy represent the oldest record of Peltopleuriformes, and the phylogenetic interrelationships of this group remain controversial. Here, we report the discovery of a new peltopleuriform, Peltopleurus nitidus sp. nov., based on eleven well-preserved specimens from the early Middle Triassic(Pelsonian, Anisian, *244 ma)of Luoping, eastern Yunnan, China. The discovery documents the oldest convincing peltopleuriform, extending the geological range of this clade by proximately two million years. Results of the phylogenetic analysis recover *** at the base of Peltopleuridae, and provide robust support for the sister-group relationships of Peltopleuridae with Thoracopteridae within the Peltopleuriformes. The male anal fin of P. nitidus shows a primitive condition unknown in other peltopleuriforms. Comparative studies of the male anal fin in P. nitidus and other peltopleuriforms shed new light on the internal fertilization in this group.

关键词： Sexual dimorphism Viviparity Peltopleuridae Thoracopteridae Triassic

Stretch-shear mode laminated metglas/Pb(Zr,Ti)O3/metglas composite with an enhanced magnetoelectric effect

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2017年第6期62卷 388-390页

作者： Chengzhou xin Jiannan ma Jing ma Cewen Nan State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China

magnetoelectric(ME)composites have recently attracted an ever-increasing interest and provoked a great number of research activities,driven by the potential applications in novel multifunctional devices,such as sensors and transducers[1].Direct ME effect,which describe the appearance of an electric polarization P upon applying a magnetic field H,is usually evaluated by the

关键词： mode Zr,Ti)O3/metglas composite with an enhanced magnetoelectric effect PZT ME Ti