检索结果-南通市图书馆

Micro-scale Abrasion and Medium Load Multiple Scratch Tests of PVD Coatings

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第05B期25卷 1199-1202页

作者： S. Poulat D.g Teer Teer Coatings Ltd Droitwich Worcestershire.U.K.Teer Coatings Ltd Droitwich Worcestershire.U.K.

Micro-scale abrasion testing is widely used to determine the abrasion resistance of thin film coatings; it is a simple technique that can easily be used as part of a quality control procedure, but it has got the disadvantage of not allowing an easy study of the wear mechanisms involved: it is difficult to estimate the load applied on each abrasive particles in the contact between the loaded ball and the specimen. The possibility of using progressive loading scratch testing, a method widely used to assess the adhesion of thin film coatings, to model the abrasive wear of coatings has been studied in the past; the use of multiple scratch tests to study the wear mechanisms corresponding to a single abrasion scratch event has also been studied in the case of bulk materials (ceramics and hard metals). Two coatings, deposited by Closed Field unbalanced Magnetron Sputter Ion Plating (CFuBMSIP) on ASP23 powder metallurgy steel substrate are chosen to be representative of the use of protective coatings in industry: titanium nitride, which is widely used to prevent tool wear, and TCL graphit-iC?, which is widely used as a wear resistant solid lubricant coating. The two coatings are first characterised by using a standard quality control procedure: their thickness is determined by the cap grinding method, their adhesion by progressive loading scratch. Then micro-scale abrasion tests performed with a slurry at a concentration which promotes grooving wear, and medium load multiple scratch tests performed with diamond indenters are completed; the results of these tests are analysed and compared to determine if there is any correlation between the two sets of results; the multiple scratch tests wear tracks are also observed to determine the wear mechanisms involved.

关键词：微量磨损乱痕硬度试验 PVD 薄膜涂层

Ecological variation along the salinity gradient in the Baltic Sea Area and its consequences for reproduction in the common goby

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2018年第2期64卷 259-270页

作者： Isabel MuCK Katja u. HEuBEL Department of Biology University of Tuibingen Auf tier Morgenstelle 28 72076 Tuibingen Germany Institute for Zoology Ecological Research Station Rees University of Cologne Grietherbusch 3a D-46459 Rees Germany Tvarminne Zoological Station University of Helsinki J.A. Palmenin tie 260 10900 Hanko Finland

Although it has become clear that sexual selection may shape mating systems and drive speciation, the potential constraints of environmental factors on processes and outcomes of sexual selection are largely unexplored. Here, we investigate the geographic variation of such environmental factors, more precisely the quality and quantity of nest resources （bivalve shells） along a salinity gradient in the Baltic Sea Area （Baltic Sea, Sounds and Belts, and Kattegat）. We further test whether we find any salinity-associated morphological differences in body size between populations of common gobies Pomatoschistus microps, a small marine fish with a resource-based mat- ing system. In a geographically expansive field study, we sampled 5 populations of P. microps occurring along the salinity gradient （decreasing from West to East） in the Baltic Sea Area over 3 consecutive years. Nest resource quantity and quality decreased from West to East, and a correla- tion between mussel size and male body size was detected. Population density, sex ratios, mating- and reproductive success as well as brood characteristics also differed between populations but with a less clear relation to salinity. With this field study we shed light on geographic variation of distinct environmental parameters possibly acting on population differentiation. We provide insights on relevant ecological variation, and draw attention to its importance in the framework of context-dependent plasticity of sexual selection.

关键词： aquatic ecology body size environmental gradient nest availability nesting resources sexual selection.

Nucleon Effective Mass in Asymmetric Nuclear Matter within Extended Brueckner Approach

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

Chinese Physics Letters 2012年第4期29卷 47-50页

作者： gAN Sheng-Xin ZuO Wei u.Lombardo Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000 graduate School of Chinese Academy of Sciences Beijing 100049 Department of Physics and Astrophysics Catania UniversityVia Santa Sofia 64I-95123Italy

The on-shell properties of the nucleon effective mass in asymmetric nuclear matter are investigated in the framework of an extended Brueckner-Hartree-Fock (BHF) *** proton and neutron effective masses in neutron-rich nuclear matter are predicted by including both the effect of ground state correlations and the threebody force (TBF) rearrangement *** this framework,the neutron effective mass is predicted *to be larger than the proton one in neutron-rich nuclear matter,i.e.,m*n ≥ m**** effect of ground state correlations turns out to be dominated at low densities and it leads to a strong enhancement of the effective *** TBF rearrangement contribution becomes predominant over the effect of ground state correlations at high densities and it reduces remarkably the absolute magnitude of the isospin splitting of the neutron and proton effective masses in neutron-rich matter at high densities.

关键词： rearrangement absolute Hartree

NEXT NEAREST NEIgHBOR EFFECT ON TETRAHEDRAL FERROuS AND OCTAHEDRAL FERRIC IRON IN CHROMITE

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

Science China Chemistry 1986年第8期29卷 889-896页

作者：李哲,j.g.STEVENS Institute of geology Academia Sinica Beijing Mssbauer Effect Data Center university of North Carolina Asheville u. S. A.

Four chromites have been studied by using Mssbauer spectroscopy. Of the spectra of four chromites studied, three spectra aro fitted to three or four Fe2+doublets in the tetrahedral A sites and one or two Fe3+doublets in the tetrahedral A sites and octahedral B sites. The fourth spectrum is fitted to one Fe3+doublet in the A sites and two Fe3+doublets in tho B sites. Constant isomer shifts of approximately 0.9 mm/s for Fe2+ions in the A sites and 0.3 mm/s for Fe3+ions in the B sites as well as gradual changing quadrupole splitting for both of the A sites and the B sites are obtained. The binomial distributions in the B sites are ealeulated. Next nearest neighbor effect is used to explain the multiple doublets caused by Fe2+ions in the A sites in the spectra of chromites Ⅰ, Ⅱ, Ⅲ and by Fe3+ions in the B sites in the spectrum of chromite Ⅳ.

关键词： tetrahedral octahedral fitted NEXT neighbor explain nearest splitting fourth umber

Evolution of deformation twins with strain rate in a mediummanganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

journal of Iron and Steel Research International 2019年第9期26卷 983-990页

作者： j. Chen j.j.Wang H.Zhang W.g.Zhang C.M.Liu Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819LiaoningChina School of Materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina Baosteel Special Steel Co. Ltd.Shanghai 200940China Northeastern Institute of Metal Materials Co. Ltd.Shenyang 110108LiaoningChina

Microstructure evolutions of the medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V (in wt.%) with stacking-fault energy of 22 mj m-2 during deformation at strain rate ranging of 10^-2-1 s^-1 were analyzed by means of X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicate that the twinning-induced plasticity effect is the main strengthening mechanism of the studied steel, whilst the transformation-induced plasticity effect only occurs at high strain rate. With an increase in strain rate, volume fraction of the deformation twins, in particular that of the secondary twins, increases significantly along with decreasing average size. When applied strain rate is higher than 10^-1 s^-1, the parallel deformation twins are turned into a crossing morphology, and the original straight twin boundaries exhibit a ladder feature, which is attributed to the interactions between regular dislocations and twin dislocations at the twin boundary. The critical strain, a key indicator of the initiation of deformation twin, decreases with increasing strain rate. In addition, the ductility and strength of medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V are mainly determined by the shape and volume fraction of deformation twins.

关键词： Medium-manganese wear-resistant steel Stacking fault Twinning-induced plasticity effect Secondary twin Strain hardening rate

Approximation properties for the genuine modi ed Bernstein-Durrmeyer-Stancu operators

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

Applied Mathematics(A journal of Chinese universities) 2020年第4期35卷 468-478页

作者： CAI Qing-bo ulku Dinlemez Kantar Bayram Cekim School of Mathematics and Computer Science Quanzhou Normal UniversityQuanzhou 362000China Department of Mathematics Faculty of ScienceGazi UniversityBesevler AnkaraTurkey

In this paper,we study on the genuine modified Bernstein-Durrmeyer-Stancu operators gn(f,x)and investigate some approximation properties of ***,we present a Voronovskaja type theorem for these *** also give some graph... 详细信息

关键词： genuine modi ed Bernstein-Durrmeyer-Stancu operators Voronovskaja type approximation theorem rate of convergence modulus of continuity

Synthesis of Nano-sized Barium Titanate Powder by Solid-state Reaction between Barium Carbonate and Titania

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2007年第5期23卷 655-658页

作者： u.Manzoor D.K.Kim Department of Physics COMSATS Institute of Information TechnologyIslamabadPakistan Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)DaejeonKorea

Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.

关键词： Barium tltanate Mechanical milling Solid-state reaction Nano particles

Vibrational resonance in a multistable system with position-dependent mass

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第11期75卷 115-134页

作者： T O Roy-Layinde K A Omoteso O T Kolebaje F O Ogunmefun R A Fasasi j A Laoye u E Vincent Department of Physics Olabisi Onabanjo UniversityAgo-IwoyeOgun StateNigeria Department of Physics Adeyemi Federal University of EducationOndoNigeria Department of Physical Sciences Redeemer’s UniversityP.M.B.230EdeNigeria Department of Physics Lancaster UniversityLancaster LA14 YBUnited Kingdom

The occurrence of vibrational resonance(VR)in a dual-frequency-driven multistable system with a spatially varying mass modelling particle with position-dependent mass(PDM)and evolving in a one-dimensional symmetric periodic potential has been investigated and reported in this *** numerically compute and analyze the response amplitude,the effects of the PDM parameters(m0,a)on the potential structure,the occurrence of VR and the bifurcation of the equilibrium *** is shown that the PDM parameters,besides controlling VR,can induce unconventional resonance patterns through the variation of the potential well *** resonant states can be influenced through the cooperation of the PDM parameters and the external forcing leading the system from multiresonance state into single and double resonance *** contributions of the fixed rest mass m0 on the VR and the PDM-induced resonance are determined by threshold conditions imposed by the magnitude of the mass nonlinear strength a.

关键词： vibrations resonance position-dependent mass multistable oscillator dualfrequency force nonlinear systems

Numerical simulation and experiment of error field measurement using luminous trace of electron beam in SST-1

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2019年第10期21卷 9-16页

作者： Someswar DuTTA Y PARAVASTu j DHONgDE H CHuDASMA S gEORgE K DHANANI A MAKWANA C DODIYA P VARMORA D K SHARMA A K SINgH u KuMAR D RAVAL u PRASAD Z KHAN R SRINIVASAN D RAju Institute for Plasma Research GandhinagarGujrat 382428India Homi Bhabha National Institute (HBNI) AnushaktinagarMumbai 400094India

In contrast to the earlier experiments conducted in other machines, here, in SST-1 the error field measurement experiment is performed with a filled gas pressure ~8×10^-4 mbar which helped to create a luminescent toroidal beam of electron path originated due to impact excitation and guided by the toroidal magnetic field. Beam path deviations are observed and recorded from radial and top ports using visible range cameras. Such creation and detection of the electron beam path differs from the earlier works where the gun emitted electron beam deviation in ultrahigh vacuum was detected on a collector-grid/fluorescent screen. In the present experiment, large beam deviations were observed. Later investigation of the experimental set-up reveals existence of a possible source of radial electric field in between the source and the vacuum vessel which are separately grounded. Thus, to understand the observed phenomena, experiments are numerically modeled with deviated TF coil set, PF coil set and the electron source location. A particle tracing code is used to follow the electron path in the magnetic field generated by the coil set of interest. Simulation results suggest that the large deviation corresponds to the E×B drifts and not due to the large field errors. Toroidally averaged field errors of the SST-1 TF coils at toroidal field of B0?=?15 kg are negligibly small ~B0?×?10^-6 or less, which should not adversely affect the plasma performance.

关键词： electron beam error field SST-1 TF coil