检索结果-南通市图书馆

comparative study of 2mol% Li- and Mn-substituted lead-free potassium sodium niobate ceramics

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2014年第12期21卷 1241-1246页

作者： Asha Dahiya O.P.Thakur J.K.Juneja Sangeeta Singh Dipti School of Applied Sciences Netaji Subhas Institute of Technology Dwarka University of Delhi Department of Physics Hindu College Department of Physics Geeta Vidya Mandir Girls College School of Physics & Material Sciences Thapar University

The effect of Li and Mn substitution on the dielectric, ferroelectric and piezoelectric properties of lead free K0.5Na0.5NbO3 （KNN） was investigated. Samples were prepared using a conventional solid state reaction method. The sintefing temperature for all the samples was 1050℃. The optimum doping concentration for the enhancement of different properties without the introduction of any other co-dopants such as Ti, Sb, and La was investigated. X-ray diffraction analysis confirmed that all the samples crystallize in a single phase perovskite structure. The dielectric properties were investigated as a function of temperature and applied electric field frequency. Compared with Li-substituted KNN （KLNN）, Mn-substituted KNN （KMNN） exhibited a higher dielectric constant εmax （i.e., 4840） at its critical transition temperature Tc （i.e., 421℃） along with a lower value of tangent loss at 10 kHz and greater values of saturation polarisation Ps （i.e., 20.14 μC/cm^2） and remnant polarisation Pr （i.e., 15.48 μC/cm^2）. The piezoelectric constant （d33） of KMNN was 178 pC/N, which is comparable to that of lead-based hard ceramics. The results presented herein suggest that B-site or Mn substitution at the optimum concentration results in good enhancement of different properties required for materials used in memory devices and other applications.

关键词： ceramics dielectric properties ferroelectricity piezoelectricity substitution comparative study

comparative study ON RESIDENTS′ PERCEPTION OF TOURISM IMPACT AT TOURIST PLACES——A Case study of Xidi, Zhouzhuang and Jiuhua Mountain

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2005年第1期15卷 70-79页

作者： SUQin CAOYou-hui LINBing-yao NanjingInstituteofGeographyandLimnology ChineseAcademyofSciencesNanjing210008P.R.China／／CollegeofNationalTerritorialResourcesandTourismAnhuiNormalUniversityWuhu241000P.R.China NanjingInstituteofGeographyandLimnology ChineseAcademyofSciencesNanjing210008P.R.China DepartmentofUrbanandResourcesSciences NanjingUniversityNanjing210093P.R.China

Based on the questionnaire investigation, the authors make a comparative study on local residents′ perception of tourism impacts in Xidi, Zhouzhuang and Jiuhua Mountain. The result shows that residents of the three places tend to have strong and consistent perception of its positive economic, socio-cultural and environmental impacts, but distinctly diverse ones of its negative impacts. Residents in Xidi and Zhouzhuang also have noticeable perception of its negative environmental impacts while those in Jiuhua Mountain have weaker perception of them. The research confirms the fact that residents are more liable to have positive perceptions at the early stage of the life cycle of the tourist places. The authors conclude that there exists a nonlinear relationship between residents′ perception and tourism development stages, and that tourism socio-cultural impact may appear at an early stage of tourism development instead of being no universal.

关键词： tourism impacts residents' perception comparative study Xidi Zhouzhuang Jiuhua Mountain

comparative study on Debris Flow Initiation in Limestone and Sandstone Spoil

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2013年第2期10卷 190-198页

作者： CHEN Ning-sheng LU Yang DENG Ming-feng HAN Da-wei ZHOU Hai-bo YANG Cheng-lin Key lab of mountain hazards and surface process Institute of mountain hazards and environmentChinese Academy of Sciences University of Chinese Academy of Sciences University of Bristol UK

Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human ***,there is a lack of detailed comparative study on debris flow initiation in different spoil *** paper describes a series of tests and analyses on debris flow characteristics(initiation,scale and mechanism) at six sites with limestone and sandstone materials near the Dujiangyan *** shows the limestone spoil contains debris flow prone clay content with high concentration of montmorillonite(highly expandable).In addition,limestone spoil is of such a low permeability that water mainly concentrates in the upper surface *** factors make it easy for the increase of pore water pressure,decline of internal friction and conhesion force,leading to the occurence of large debris *** contrast,the sandstone spoil is less problematic and causes no major debris flow *** on our research on the mechanism,the"stereometric drainage"method is sucessfully applied to control limestone spoil debris flows.

关键词： Debris flows comparative study Reconstruction spoil Initiation mechanism Mitigation measures

comparative study of HFACS and the 24Model accident causation models

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2017年第3期14卷 570-578页

作者： Gui Fu Jia-Lin Cao Lin Zhou Yuan-Chi Xiang School of Resources and Safety Engineering China University of Mining and Technology (Beijing) Beijing 100083 China

A comparative study is conducted to compare the theory and application effect of two accident causation models, the human factors analysis and classification system（HFACS） and the accident causation ＂2-4＂ model（24 Model）, as well as to provide a reference for safety researchers and accident investigators to select an appropriate accident analysis method. The two models are compared in terms of their theoretical foundations, cause classifications, accident analysis processes, application ranges, and accident prevention strategies. A coal and gas outburst accident is then analyzed using both models, and the application results are compared. This study shows that both the 24 Model and HFACS have strong theoretical foundations, and they can each be applied in various domains. In addition, the cause classification in HFACS is more practical, and its accident analysis process is more convenient. On the other hand, the 24 Model includes external factors, which makes the cause analysis more systematic and comprehensive. Moreover, the 24 Model puts forward more corresponding measures to prevent accidents.

关键词： HFACS Accident causation "2-4" model comparative study Unsafe acts External causes Coaland gas outburst accident

comparative study between novel self cross-linking and conventional fluorinated acrylic latex

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2011年第10期22卷 1249-1252页

作者： Li Jun Chen School of Chemical Engineering and Materials Science Zhejiang University of Technology Hangzhou 310032 China

Novel self cross-linking fluorinated acrylic latex（SCLFAL） has been successfully prepared via starved seeded semi-batch emulsion *** resultant SCLFAL is characterized by Fourier transform infrared（FTIR） *** angle （CA） and glass transition temperature（T_g） of the film are *** show that CA and T_g of the film can be improved when the moderate amount of HPMA is introduced into the mixed monomers.

关键词： Self cross-linking fluorinated acrylic latex Preparation comparative study

comparative study on Diagonal Strut Model of Infill Wall

在线全文

学校读者我要写书评

暂无评论

Structural Durability & Health Monitoring 2018年第3期12卷 169-187页

作者： Zhenling Chai Zixiong Guo Xiaojuan Liu Yunfan Jiang College of Civil Engineering Huaqiao UniversityXiamen361021China

The equivalent diagonal strut models of infill wall mainly include the single strut model and multi-strut ***,several equivalent strut models and their characteristics are introduced in this ***,model analysis and pushover analysis are carried out on infilled frame models with the aid of the software *** typical single strut models and a typical three-strut model are used to simulate the panel of the frames *** is indicated that the period reduction factor of the frame with a three-strut model is close to the value recommended by the current *** infill wall has great influence on the overall stiffness,bearing capacity and weak position of the *** stiffness and the bearing capacity of the infilled frame increase with the increase of the number of the infill *** unfilled story is the weak position of the infilled frame,and when the unfilled story at the bottom of the infilled frame,the seismic response of the upper infill layer decreases with the increasing of the number of unfilled story.

关键词： Infill wall equivalent strut model comparative study pushover analysis

comparative study of different theories on active earth pressure

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2012年第10期19卷 2933-2939页

作者： S.P.Yap F.A.Salman S.M.Shirazi Department of Civil Engineering Faculty of EngineeringUniversity of MalayaKuala Lumpur 50603Malaysia

Determination of distribution and magnitude of active earth pressure is crucial in retaining wall designs. A number of analytical theories on active earth pressure were presented. Yet, there are limited studies on comparison between the theories. In this work, comparison between the theories with finite element analysis is done using the PLAXIS software. The comparative results show that in terms of distribution and magnitude of active earth pressure, RANKINE＇s theory possesses the highest match to the PLAXIS analysis. Parametric studies were also done to study the responses of active earth pressure distribution to varying parameters Increasing soil friction angle and wall friction causes decrease in active earth pressure. In contrast, active earth pressure increases with increasing soil unit weight and height of wall. RANK/NE＇s theory has the highest compatibility to finite element analysis among all theories, and utilization of this theory leads to proficient retaining wall design.

关键词： active earth pressure retaining wall PLAXIS comparative study RANKINE's theory COULOMB's theory

A comparative study of CNN-and Transformer-Based Visual Style Transfer

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2022年第3期37卷 601-614页

作者： Hua-Peng Wei Ying-Ying Deng Fan Tang Xing-Jia Pan Wei-Ming Dong School of Artificial Intelligence Jilin UniversityChangchun 130012China National Laboratory of Pattern Recognition Institute of AutomationChinese Academy of SciencesBeijing 100190China Youtu Laboratory Tencent IncorporatedShanghai 200233China

Vision Transformer has shown impressive performance on the image classification *** that most existing visual style transfer(VST)algorithms are based on the texture-biased convolution neural network(CNN),here raises the question of whether the shape-biased Vision Transformer can perform style transfer as *** this work,we focus on comparing and analyzing the shape bias between CNN-and transformer-based models from the view of VST *** comprehensive comparisons,we propose three kinds of transformer-based visual style transfer(Tr-VST)methods(Tr-NST for optimization-based VST,Tr-WCT for reconstruction-based VST and Tr-AdaIN for perceptual-based VST).By engaging three mainstream VST methods in the transformer pipeline,we show that transformer-based models pre-trained on ImageNet are not proper for style transfer *** to the strong shape bias of the transformer-based models,these Tr-VST methods cannot render style *** further analyze the shape bias by considering the influence of the learned parameters and the structure *** prove that with proper style supervision,the transformer can learn similar texture-biased features as CNN *** the reduced shape bias in the transformer encoder,Tr-VST methods can generate higher-quality results compared with state-of-the-art VST methods.

关键词： transformer convolution neural network visual style transfer comparative study

comparative study on heat transfer enhancement of metal foam and fins in a shell-and-tube latent heat thermal energy storage unit

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy Storage and Saving 2023年第3期2卷 487-494页

作者： Shuai Zhang Ziyuan Li Yuying Yan Mark Alston Limei Tian Faculty of Engineering University of NottinghamUniversity ParkNottinghamNG72RDUK Key Laboratory of Bionic Engineering(Ministry of Education) Jilin UniversityChangchun130022China

Metal foam and fins are two popular structures that are employed to enhance the heat transfer of phase change materials in shell-and-tube heat storage ***,it remains unclear which structure is better in terms of energy storage *** this study,the heat transfer enhancement performances of metal foam and fins are compared to provide guidance on the optimal structure to be chosen for practical *** fin structures(four fins,two vertical fins,and two horizontal fins)are *** the full configuration(volume fraction of metal=3%),the unit with four fins was found to have a faster melting rate than those with vertical or horizontal *** other words,increasing the number of fins helps to accelerate the melting ***,the unit with metal foam enhancement has the highest melting *** the half configuration(volume fraction of metal=1.5%),the melting rate of the unit enhanced by metal foam is significantly decreased,whereas there is no remarkable changes in the units enhanced by ***,metal foam is still shown to be the best thermal *** energy storage rate of the unit enhanced by metal foam can be up to 10 times higher than that of the unit enhanced by fins.

关键词： comparative study Metal foam and fin Thermal energy storage Shell-and-tube heat storage unit Melting front