检索结果-南通市图书馆

Assessment of wear micromechanisms on a laser textured cemented carbide tool during abrasive-like machining by FIB/FESEM

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Friction 2021年第3期9卷 656-664页

作者： Shiqi FANG Dirk BÄHRE luis LLANES Institute of Production Engineering Saarland UniversitySaarbrücken 66123Germany CIEFMA-Department of Materials Science and Engineering EEBE-Campus Diagonal BesòsUniversitat Politècnica de CatalunyaBarcelona 08019Spain

The combined use of focused ion beam(FIB)milling and field-emission scanning electron microscopy inspection(FESEM)is a unique and successful approach for assessment of near-surface phenomena at specific and selected *** this study,a FIB/FESEM dual-beam platform was implemented to docment and analyze the wear micromechanisms on a laser-surface textured(LST)hardmetal(HM)*** particular,changes in surface and microstructural integrity of the laser-sculptured pyramids(effective cutting microfeatures)were characterized after testing the LST-HM tool against a steel workpiece in a workbench designed to simulate an external honing *** was demonstrated that:(1)laser-surface texturing does not degrade the intrinsic surface integrity and tool effectiveness of HM pyramids;and(2)there exists a correlation between the wear and loading of shaped pyramids at the local ***,the enhanced performance of the laser-textured tool should consider the pyramid geometry aspects rather than the microstructure assemblage of the HM grade used,at least for attempted abrasive applications.

关键词： focused ion beam(FIB) field-emission scanning electron microscopy inspection(FESEM) cemented carbides laser surface texturing abrasive machining processes wear

Linear viscoelastic behavior of asphalt binders and mixtures containing very high percentages of reclaimed asphalt pavement

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2023年第8期17卷 1211-1227页

作者： Reza IMANINASAB luis LORIA-SALAZAR Alan CARTER Construction Engineering Department École de Technologie Supérieure(ÉTS)University of QuebecMontreal H3C 1K3Canada Civil Engineering Department Universidad Isaac NewtonSan José10108Costa Rica

The primary aim of this study is to correlate the impact of aggregates,if any,on the viscoelastic behavior of rejuvenated asphalt mixtures containing very high amounts of reclaimed asphalt pavement(RAP)(>50%).First,gradation of 100%RAP was rectified,using a modified Bailey method by adding virgin aggregates to achieve two coarse dense-graded and one fine dense-graded *** modulus test was then performed from−35 to+35℃and 0.01–10 *** addition to performance grade(PG)testing,extracted and recovered binders from different asphalt mixtures underwent shear complex modulus test within−8℃to high temperature PG and frequencies from 0.001 to 30 ***−Cole,Black space,complex modulus and phase angle master curves were constructed and ShiftHomothety-Shift in time-Shift(SHStS)transformation was used to compare the linear viscoelastic behavior of asphalt binders and *** influence of aggregates on the viscoelastic behavior of asphalt mixtures depends on temperature and/or *** role of asphalt binders in the behavior of asphalt mixtures is more pronounced at high temperatures and the effect of the aggregate structure increases as the temperature *** maximum difference(60%to 70%)in the viscoelastic behavior of the binder and mixture based on SHStS transformed Cole−Cole curves is within the phase angle of 15°–20°.

关键词： RAP complex modulus SHStS transformation rejuvenation behavior of asphalt binder and mixture

Identification of Arceuthobium globosum using unmanned aerial vehicle images in a high mountain forest of central Mexico

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2020年第5期31卷 1759-1771页

作者： luis A.Leon-Banuelos Angel R.Endara-Agramont William gomez-Demetrio Carlos G.Martınez-Garcıa E.Gabino Nava-Bernal 50000 TolucaMexicoMexico

The identification of forests infested by parasitic plants is important for the design of appropriate control and prevention *** images and geographic information systems are commonly used to analyze the presence of pest and parasitic plants in the *** there is a need for finer *** the last decade,the use of unmanned aerial vehicles has become increasingly common for capturing aerial images(<10 cm per pixel).The objective of the study was to obtain RGB values(Red,Green and Blue)through the colorimetric ranges for use in identification of Yellow Dwarf Mistletoe(YDM)(Arceuthobium globosum)in aerial images taken in a forest of central Mexico via a programmed *** tonalities of YDM were classified according to its phenological stages,***(young stage),yellow(adult stage),and brown(senescence stage),considering two light intensities,sunny and ***-parametric tests were used in statistical *** Spearman test showed significant negative correlation(p<0.001)between phenological stage and colour,indicating that lower RGB values were associated with greater *** differences between groups were analysed using Kruskal–Wallis(p<0.01)and Mann–Whitney tests(p<0.01).The applied algorithm identified the presence and predominant colours of YDM according to its phenological stage.

关键词： Colorimetric analysis RGB Pinus hartweggi Parasitic plants Remote sensing

A renewal theory based performance and configuration framework of the IEEE 802.11ah RAW mechanism

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2023年第1期9卷 236-251页

作者： Hamid Taramit luis Orozco-Barbosa Abdelkrim Haqiq Hassan First University of Settat Faculty of Sciences and TechniquesComputerNetworksMobility and Modeling Laboratory:IR2M26000 SettatMorocco Albacete Research Institute of Informatics Universidad de Castilla-La Mancha02006 AlbaceteSpain

IEEE 802.11ah is a new Wi-Fi standard for sub-1Ghz communications,aiming to address the challenges of the Internet of Things(IoT).Significant changes in the legacy 802.11 standards have been proposed to improve the network performance in high contention scenarios,the most important of which is the Restricted Access Window(RAW)*** mechanism promises to increase the throughput and energy efficiency by dividing stations into different *** this scheme,only the stations belonging to the same group may access the channel,which reduces the collision probability in dense ***,the standard does not define the RAW grouping *** this paper,we develop a new mathematical model based on the renewal theory,which allows for tracking the number of transmissions within the limited RAW slot contention period defined by the *** then analyze and evaluate the performance of RAW *** also introduce a grouping scheme to organize the stations and channel access time into different groups within the ***,we propose an algorithm to derive the RAW configuration parameters of a throughput maximizing grouping *** additionally explore the impact of channel errors on the contention within the time-limited RAW slot and the overall RAW optimal *** presented analytical framework can be applied to many other Wi-Fi standards that integrate periodic channel *** simulations using the MATLAB software validate the analytical model and prove the effectiveness of the proposed RAW configuration scheme.

关键词： IEEE 802.11ah Performance evaluation Renewal theory RAW mechanism Internet of things

Singular Integrals with Variable Kernels in Dyadic Settings

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2023年第8期39卷 1565-1579页

作者： Hugo AIMAR Raquel CRESCIMBENI luis NOWAK IMAL-CONICET and UNL Santa FeArgentina Departamento de Matemática FaEAUNCo.and IITCI-CONICETNeuquenArgentina

In this paper we explore conditions on variable symbols with respect to Haar systems,defining Calderón–Zygmund type operators with respect to the dyadic metrics associated to the Haar bases. We show that Petermichl’s dyadic kernel can be seen as a variable kernel singular integral and we extend it to dyadic systems built on spaces of homogeneous type.

关键词： Singular integrals spaces of homogeneous type Petermichl’s operator Haar basis

Recent advances on first-principles modeling for the design of materials in CO2 capture technologies

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2019年第7期27卷 1554-1565页

作者： Yue Yuan Huabei You luis Ricardez-Sandoval Chemical Engineering Department Tianjin UniversityTianjin 300072China Chemical Engineering Department University of Waterloo200 University Ave WWaterlooON N2L 3G1Canada

Novel technologies in consideration of industrial sustainability(IS)are in urgent need to satisfy the increasing demands from the *** realizes the production of materials while maintaining environmental and resource *** chemical materials used in CO2 capture and storage(CCS)technologies play a significant role in the disposal of greenhouse gas emissions coming from large stationary fossil-fired power plants,which breaks the principle of IS and brings severe environmental *** study aims at providing a detailed review of first-principles modeling(density functional theory,DFT)of materials in CO2 capture *** analysis provides insight into the atomic properties of the studied systems and builds an efficient guidance of the future design of the materials used in CO2 capture *** materials including oxygen carriers,metal organic frameworks,membranes,zeolites,ionic liquids and some other promising candidates are *** computational studies bring the outcomes of the adsorption behaviors,structural characteristics and accurate force fields of the studied materials in short turn-around times at low *** review can stimulate the design of novel materials with specific target of CO2 capture and promote the industrial sustainability of fossil fuel combustion technologies.

关键词： Industrial sustainability CO2 capture Density functional theory Fossil fuels

Cellular automata model for traffic flow with safe driving conditions

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第5期23卷 216-226页

作者： María Elena Lárraga luis Alvarez-Icaza Instituto de Ingeniería Universidad Nacional Autónoma de México04510Coyoacán D.F.México

In this paper, a recently introduced cellular automata （CA） model is used for a statistical analysis of the inner micro-scopic structure of synchronized traffic flow. The analysis focuses on the formation and dissolution of clusters or platoons of vehicles, as the mechanism that causes the presence of this synchronized traffic state with a high flow. This platoon formation is one of the most interesting phenomena observed in traffic flows and plays an important role both in manual and automated highway systems （AHS）. Simulation results, obtained from a single-lane system under periodic boundary conditions indicate that in the density region where the synchronized state is observed, most vehicles travel together in pla- toons with approximately the same speed and small spatial distances. The examination of velocity variations and individual vehicle gaps shows that the flow corresponding to the synchronized state is stable, safe and highly correlated. Moreover, results indicate that the observed platoon formation in real traffic is reproduced in simulations by the relation between vehicle headway and velocity that is embedded in the dynamics definition of the CA model.

关键词： traffic flow models synchronized traffic cellular automata platoons formation

Software Package Evaluation for Lyapunov Exponent and Others Features of Signals Evaluating Condition Monitoring Performance of Nonlinear Dynamic Systems

在线全文

学校读者我要写书评

暂无评论

Journal of Energy and Power Engineering 2015年第5期9卷 443-451页

作者： Julio Cesar gomez-Mancilla luis Manuel Palacios-Pineda Valeriy Nosov Vibrations & Rotordynamies Laboratory ESIME (Superior School of Mechanical and Electrical Engineering) IPN (National Polytechnic Institute) Zaeateneo Professional Center Mexieo D. F. 07738 Mexieo Graduated and Research Department Technological Institute of Pachuca Pachuca 42083 Mexico

Efficient use of industrial equipment, increase its availability, safety and economic issues spur strong research on maintenance programs based on their operating conditions. Machines normally operate in a linear range, but when malfunctions occur, nonlinear behavior might set in. By studying and comparing five nonlinear features, which listed in decreasing order by their damage detection capability are： LLE （largest Lyapunov exponent）, embedded dimension, Kappa determinism, time delay and cross error values; i.e., LLE performs best. Using somewhat similar ideas from Chaos control, i.e., vary the ＂mass imbalance＂ forcing parameters, we aim to stabilize the Lorenz equation. Quite interestingly, for certain imbalance excitation values, the system is stabilized. The previous even when paradigmatically chaotic parameters for Lorenz system are used （plus our forcing terms）. This quasi-control approach is validated studying signals obtained from the previously mentioned lab test. Finally, it is concluded that analyzing and comparing nonlinear features extracted from baseline vs. malfunction condition （test acquired）, one might increase the efficiency and the performance of machine condition monitoring.

关键词： Modified Lorenz equation largest Lyapunov exponent nonlinear features chaos control test validation.

Invasive-invaded system of non-Lipschitz porous medium equations with advection

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

International Journal of Biomathematics 2021年第7期14卷 299-327页

作者： Jose luis Diaz Palencia Escuela Politecnica Superior Universidad Francisco de Vitoria Ctra.Pozuelo-Majadahonda Km 1 80028223Pozuelo de AlarconMadrid

This work provides analytical results towards applications in the field of invasive-invaded systems modeled with nonlinear diffusion and with *** results focus on showing regularity,existence and uniqueness of weak solutions using the condition of a nonlinear slightly positive parabolic operator and the reaction-absorption monotone *** coupling in the reaction-absorption terms,that characterizes the species interaction,impedes the formulation of a global comparison principle that is shown to exist ***,this work provides analytical solutions obtained as selfsimilar minimal and maximal profiles.A propagating diffusive front is shown to exist until the invaded specie notes the existence of the *** the desertion of the invaded st arts,the diffusive front vanishes globally and the nonlinear diffusion concentrates only on the propagating tail which exhibits finite ***,the invaded specie is shown to exhibit an exponential decay along a characteristic *** exponential decay is not trivial in the nonlinear diffusion case and confirms that the invasive continues to feed on the invaded during the desertion.

关键词： Nonlinearity reaction absorption coupled system diffusion porous media