检索结果-南通市图书馆

Chinese Journal of Polymer Science 2021年第2期39卷 228-236,I0008页

作者： Long Chen Xiao Wu Xiao-Fang zhang jian-ming zhang Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-plasticsQingdao University of Science&TechnologyQingdao 266042China

Developing an effective method for improving the reproducibility of positive temperature coefficient(PTC)effect is of great significance for large-scale application of polymer based PTC composites,owing to its contribution to the security and ***,we developed a carbon black(CB)/high density polyethylene(HDPE)/poly(vinylidene fluoride)(PVDF)composite with outstanding PTC reproducibility,by incorporating 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([OMIm][NTf2])into the *** multiple repeated temperature cycles,the PTC performance of as-prepared material keeps almost unchanged and the varition of resistance at room temperature is less than 7%.Our studies revealed that[OMIm][NTf2]contributes to the improvement of PTC reproducibility in two ways:(i)it acts as an efficient plasticizer for refining the co-continuous phase morphology of HDPE/PVDE blends;(ii)it inhibits the crystallization of PVDF through the dilution effect,leading to more overlaps of the volume shrinkage process of HDPE and PVDF melt which results in the decrease of interface gap between HDPE and *** study demonstrated that ionic liquids as the multifunctional agents have great potential for improving the reproducibility in the application of the binary polymer based PTC composites.

关键词： Conductive polymer composites Reproducibility Positive temperature coefficient Ionic liquid

Redshift drift reconstruction for some cosmological models from observations

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2013年第12期13卷 1397-1408页

作者： ming-jian zhang Wen-Biao Liu Department of Physics Institute of Theoretical PhysicsBeijing Normal University

Redshift drift is a tool to directly probe the expansion history of the uni- verse. Based on the Friedmann-Robertson-Walker framework, we reconstruct the ve- locity drift and deceleration factor for several cosmological models using observa- tional H（z） data from the differential ages of galaxies and baryon acoustic oscillation peaks, luminosity distance of Type Ia supernovae, cosmic microwave background shift parameter, and baryon acoustic oscillation distance parameter. They can, for the first time, provide an objective and quantifiable measure of the redshift drift. We find that reconstructed velocity drift with different peak values and corresponding redshifts can potentially provide a method to distinguish the quality of competing dark energy mod- els at low redshifts. Better fitting between models and observational data indicate that current data are insufficient to distinguish the quality of these models. However, by comparing with the simulated velocity drift from Liske et al, we find that the Dvali- Gabadadze-Porrati model is inconsistent with the data at high redshift, which origi- nally piqued the interest of researchers in the topic of redshift drift. Considering the deceleration factor, we are able to give a stable instantaneous estimation of a transition redshift of zt ~ 0.7 from joint constraints, which incorporates a more complete set of values than the previous study that used a single data set.

关键词： redshift drift: cosmology -- reconstruction -- observation

NUMERICAL METHOD FOR MULTI-BODY FLUID INTERACTION BASED ON IMMERSED BOUNDARY METHOD

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2011年第4期23卷 476-482页

作者： ming Ping-jian zhang Wen-ping School of Power and Energy Engineering Harbin Engineering University Harbin 150001 China

A Cartesian grid based on Immersed Boundary Method （IBM）, proposed by the present authors, is extended to unstructured grids. The advantages of IBM and Body Fitted Grid （BFG） are taken to enhance the computation efficiency of the fluid structure interaction in a complex domain. There are many methods to generate the BFG, among which the unstructured grid method is the most popular. The concept of Volume Of Solid （VOS） is used to deal with the multi rigid body and fluid interaction. Each body surface is represented by a set of points which can be traced in an anti-clockwise order with the solid area on the left side of surface. An efficient Lagrange point tracking algorithm on the fixed grid is applied to search the moving boundary grid points. This method is verified by low Reynolds number flows in the range from Re = 100 to 1000 in the cavity with a moving lid. The results are in a good agreement with experimental data in literature. Finally, the flow past two moving cylinders is simulated to test the capability of the method.

关键词： fluid-structure interaction Immersed Boundary Method (IBM) Volume Of Solid (VOS) unstructured grids

Observational constraint on the dark energy scalar field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2021年第4期45卷 440-450页

作者： ming-jian zhang Hong Li School of Electronic and Information Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of ScienceBejjing 100049China

In this paper,we study three scalar fields,namely the quintessence,phantom,and tachyon fields,to explore the source of dark energy via the Gaussian processes method from the background and perturbation growth rate *** corresponding reconstructions suggest that the dark energy should be ***,the quintom field,which is a combination of the quintessence and phantom fields,is powerfully favored by the *** mean values indicate that the potential V(φ) in the quintessence field is a double exponential function,whereas V(φ) in the phantom field is a double Gaussian *** reconstruction can provide an important reference for the scalar field *** two types of data employed reveal that the tachyon field is disadvantageous for describing the cosmic acceleration.

关键词： dark energy scalar field Gaussian processes

Study on Phase Transformation Behavior of Strain-induced PLLA Mesophase by Polarized Infrared Spectroscopy

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2019年第3期37卷 253-257页

作者： jian Hu Li-Li Han Tong-Ping zhang Yong-Xin Duan jian-ming zhang Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-plastics Qingdao University of Science& Technology

The structural transformation of mesophase to crystalline phase of strain-induced poly(L-lactic acid) has been investigated by differential scanning calorimetry(DSC) and in situ temperature dependent polarized Fourier transform infrared(FTIR) spectroscopy. It is found that, as the drawing temperature increases, melting of strain-induced mesophase in the heating process can remarkably interfere the crystallization behavior subsequently. Coupling with in situ polarized FTIR, from 60 °C to 76 °C, the mesophase melts partially rather than completely melting, and changes immediately to three-dimensional ordered structure. Of particular note, through monitoring the subtle spectral change in the critical phase transformation temperature from 60 °C to 64 °C, it is clearly demonstrated that relaxation of oriented amorphous chains initially takes place prior to the melting of mesophase.

关键词： Structural transformation Mesophase Strain-induced Polarized IR spectroscopy

High Performance of PVA Nanocomposite Reinforced by Janus-like Asymmetrically Oxidized Graphene:Synergetic Effect of H-bonding Interaction and Interfacial Crystallization

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2022年第4期40卷 373-383页

作者： Ning zhang Bin zhang Yong Pang Hong-Sheng Yang Lu Zong Yong-Xin Duan jian-ming zhang Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-plasticsQingdao University of Science&TechnologyQingdao 266042China State Key Laboratory of Bio-fibers and Eco-textiles Qingdao UniversityQingdao 266071China

Macromolecule nanocrystal network and strong interfacial interaction are always beneficial to enhance the mechanical property of polymer-based ***(vinyl alcohol)(PVA),a typical biocompatible semicrystalline polymer,is an ideal candidate for preparing high performance polymer-based ***,the rich hydrogen bonds between PVA matrix and graphene oxide(GO)can disrupt the formation of PVA nanocrystal ***,it remains a great challenge to achieve both strong and tough PVA-GO ***,by introducing a novel Janus-like amphiphilic graphene oxide(JGO),both hydrogen bonding and interfacial crystallization have been constructed between JGO sheets and PVA *** from amphiphilic interfacial interaction and the enhanced crystal network,both PVA-JGO dried films and their swollen hydrogel films show superior mechanical properties than those of traditional PVA-GO ***-JGO dried films exhibit a 264%improvement of toughness at a JGO loading of 1 wt%.Meanwhile,the corresponding PVA-JGO swollen hydrogel films display simultaneous improvement of nearly 8 times increase of tensile strength and 20 times increase of toughness compared to traditional PVA-GO *** work indicates multiple interfacial interactions and macromolecule crystal networks can be concurrent in PVA nanocomposites by innovative modification of nanofillers,providing a new strategy to construct PVA nanocomposites with high strength and high *** integration of outstanding mechanical and swelling resistance properties on PVA-JGO nanocomposite films render their promising applications,such as packaging and toughening hydrogel materials.

关键词： Poly(vinyl alcohol) Janus-like graphene oxide Hydrogen-bonding interactions Interfacial crystallization Amphiphilicity

Broadband channel measurement and analysis

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2006年第3期13卷 24-28页

作者： zhang ming zhang jian-hua jianG Jun zhang Ping WU Yu-fei Wireless Technology Innovation Labs (WTI) Beijing University of Posts and Telecommunications Beijing 100876 China

An outdoor propagation measurement campaign for beyond 3G （B3G） as well as a wide-band indoor measurement campaign have been performed recently in Beijing, China, in which the sounding signals are transmitted by an one-antenna base station and received by a two-antenna mobile receiver operated at 3.49～3.51 GHz bandwidth. Different scenarios： stationary line-of-sight （LoS）, stationary non-LoS （NLoS） scenarios, and dynamic NLoS are deliberately chosen in a classic urban environment and office environment. The initial results are presented in this article. Parameters including vector channel impulse response, path loss, rays number, excess delay spread etc. are extracted, analyzed, and briefly reported here.

关键词： Broadband measurement Beyond 3G path loss,multipath delay rays number

Mechanical Properties of Silicone Rubber Using Carbosilane Dendrimers as the Cross-linker

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2005年第10期16卷 1383-1385页

作者： Shi Gui ZHAO Chuan jian ZHOU jian ming zhang Sheng Yu FENG School of Material Science and Engineering Shandong University Jinan 250061 School of Chemistry and Chemical Engineering Shandong University Jinan 250100

Peroxide-cured high-temperature vulcanized （HTV） silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si（CHaCH=CH2）4, as the cross-linker. It showed that this ki... 详细信息

关键词： Carbosilane dendrimers cross-linker silicone rubber mechanical properties.

A Better Reconciliation of Hubble Tension in the Dark Energy Scalar Field

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2023年第3期23卷 37-45页

作者： Le Fu Li Chen Maoyou Yang Junmei Wang ming-jian zhang School of Information and Automation Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China International School for Optoelectronic Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China

Hubble tension between the local measurement and global observation has been a key problem in *** this paper,we consider the quintessence scalar field,phantom field and quintom field as the dark energy to reconcile this *** from most previous work,we start from the dimensionless equation of state(w)of dark energy,not a parameterization of *** combined analysis shows that observational data sets favor Hubble constant H0=71.3-0.917+0.854 km s^(-1)Mpc^(-1),which can reconcile Hubble tension within 1.20σ.We also perform a Bayes factor analysis using the MCEvidence code,and confirm that the phantom scalar field is still the most *** investigate the reason of Hubble tension,we analyze the density *** comparison shows that the scalar fields provide a slightly largerΩbh2 and smallerΩch2 than the standardΛCDM *** finally analyze a possible reason of Hubble tension from the kinematic acceleration?.We find an interesting physical *** acceleration a in these scalar fields are similar as theΛCDM model at about redshift z>***,they increase and deviate from each other at low redshift,especially in the near *** the?in phantom scalar field will decrease in the future.

关键词： parameter potential observational

Transient acceleration in f(T) gravity

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第2期16卷 13-18页

作者： Jing-Zhao Qi Rong-Jia Yang ming-jian zhang Wen-Biao Liu Department of Physics Institute of Theoretical Physics Beijing Normal University College of Physical Science and Technology Hebei University

Recently an f （T） gravity based on the modification of teleparallel gravity was proposed to ex-plain the accelerated expansion of the universe. We use observational data from type Ia supernovae, baryon acoustic oscillations, and cosmic microwave background to constrain this f（T） theory and reconstruct the effective equation of state and the deceleration parameter. We obtain the best-fit values of parameters and find an interesting result that the constrained f（T） theory allows for the accelerated Hubble expansion to be a transient effect.

关键词： f(T) gravity cosmology -- reconstruction -- observation