检索结果-南通市图书馆

Effects of Austempering and martempering Processes on Amount of Retained Austenite in Cr-mo Steels (FmU-226) Used in mill Liner

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2010年第2期17卷 53-58页

作者： m h Shaeri h Saghafian S G Shabestari School of metallurgy and materials Engineering Iran University of Science and Technology

The presence of retained austenite gives rise to deterioration of the wear resistance and fracture strength of Cr-mo steels in many cases. Thus, the effects of heat treatments including direct quenching, martempering, and austempering on the retained austenite existing in the microstrueture of these steels were investigated. Specimens were austenized at 950 ℃ followed by direct quenching using compressed and still air. The specimens were also isothermally quenched in salt bath at 200 and 300 ℃ for 2, 8, 30, and 120min. microstructures of the specimens were studied using optical microscope （traditional black and white etching as well as color etching）, scanning electron microscope （SEm）, microhardness tester, and X-ray diffraction （XRD）. The results showed that the lowest amount of retained austenite in the microstructure was obtained in the specimens quenched isothermally at 300 ℃ for 120 min.

关键词： Cr-mo steel austempering martempering retained austenite microstructure

hybrid reinforced thermoset polymer composite in energy absorption tube application:A review

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2018年第4期14卷 291-305页

作者： A.B.m.Supian S.m.Sapuan m.Y.m.Zuhri E.S.Zainudin h.h.Ya Department of mechanical and manufacturing Engineering Universiti Putra Malaysia Laboratory of Bio Composite Technology Institute of Tropical Forestry and Research Products (INTROP)Universiti Putra Malaysia Department of mechanical Engineering Universiti Teknologi Petronas

The custom of hybridization fibre composite in energy absorption tube application has gained the attention of structural crashworthiness in composite material industry. Thus, the approach of this review is to understand the effect in hybridization within metal/synthetic fibre composite, synthetic/synthetic fibre composite and nature/synthetic fibre composite as energy absorption tube, which reflects on the energy absorption characteristics and crashworthiness behaviors in previous the study. By way of instance, a wide range of methodology and particular parameter in previous study such as the effect in fibre arrangement, matrix polymer, technique of fabrication, fibre treatment(natural fibre), design in geometry/cross-section and others mechanism of hybrid fibre composite tube are highlighted which to comprehend the capability of the mechanical performance and collapsible behavior as sacrificial structure in high-performance structure applications. moreover, in the recently studies there have been many of the research regarding structural materials as energy absorption tube has been introduced such as metal/matrix composites, new alloy metals and polymer composites which intended to evaluate the performance of these materials into circumstance in loading and impact characteristic. Therefore, this review article is trying to explore the research articles related to the effect of hybridization fibres and thermoset polymer as reinforcement for energy absorption tube research and expected would provide an information and idea which to expend the knowledge in future study of hybridization effect for energy absorption tube, moreover the development for future potential as new hybrid composite fibre materials from the natural/synthetic fibres reinforced composite material in employing of high-performance energy absorption tube application is still less discover and highlighted.

关键词： Energy absorption tube hybrid composites Collapse behavior Crashworthiness

Formation region of emitted α and heavier particles inside radioactive nuclei

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2020年第7期44卷 118-125页

作者： W.m.Seif A.m.h.Abdelhady Cairo University Faculty of ScienceDepartment of Physics12613 GizaEgypt Beni-Suef University Faculty of Navigation Science and Space Technology62514 Beni-SuefEgypt

We investigate the formation distance(R0)from the center of the radioactive parent nucleus at which the emitted cluster is most probably *** calculations are performed microscopically starting with the solution to the time-independent Schr?dinger wave equation for the cluster-core system,using nuclear potentials based on the Skyrme-SLy4 nucleon-nucleon interactions and folding Coulomb potential,to determine the incident and transmitted wave functions of the *** results show that the emitted cluster is mostly formed in the pre-surface region of the nucleus,under the effect of Pauli blocking from the saturated core *** deeperα-formation distance inside the nucleus allows less preformation probability and indicates a more stable nucleus for a longer ***,theα-particle tends to be formed at a slightly deeper region inside the nuclei,with larger isospin asymmetry,and in the closed shell *** the heavy clusters,we observed that the formation distance of the emitted clusters heavier thanα-particle increased via increasing the isospin asymmetry of the formed cluster rather than by increasing its mass *** partial half-life of a certain cluster-decay mode increased with increase of either the mass number or the isospin asymmetry of the emitted cluster.

关键词： alpha-decay cluster decay Skyrme-SLy4 nucleon-nucleon interaction formation region

Finite Groups with Certain S-Permutable and GS-maximal Subgroups

在线全文

学校读者我要写书评

暂无评论

Algebra Colloquium 2020年第4期27卷 661-668页

作者： A.m.Elkholy m.h.Abd-Ellatif Department of mathematics and Computer Science Faculty of Science Beni-Suef University62511 Beni-SuefEgypt

Let G be a finite group and h a subgroup of *** say that h is S-permutable in G if h permutes with every Sylow subgroup of G.A group G is called a generalized smooth group(GS-group)if[G/L]is totally smooth for every subgroup L of G of prime *** this paper,we investigate the structure of G under the assumption that each subgroup of prime order is S-permutable if the maximal subgroups of G are GS-groups.

关键词： smooth groups subgroup lattices S-permutability

Effect of substitution group on dielectric properties of 4h-pyrano [3,2-c] quinoline derivatives thin films

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 B 2016年第7期25卷 440-449页

作者： h m Zeyada F m El-Taweel m m El-Nahass m m El-Shabaan Department of Physics Faculty of Science Damietta University Department of Chemistry Faculty of Science Damietta University Department of Physics Faculty of Education Ain Shams University

The AC electrical conductivity and dielectrical properties of 2-amino-6-ethyl-5-oxo-4-（3-phenoxyphenyl）-5,6-dihydro-4h-pyrano[3, 2-c]quinoline-3-carbonitrile（Ph-hPQ） and 2-amino-4-（2-chlorophenyl）-6-ethyl-5-oxo-5,6-dihydro-4h-pyrano [3, 2-c] quinoline-3-carbonitrile（Ch-hPQ） thin films were determined in the frequency range of 0.5 k hz–5 mhz and the temperature range of 290–443 K. The AC electrical conduction of both compounds in thin film form is governed by the correlated barrier hopping（CBh） mechanism. Some parameters such as the barrier height, the maximum barrier height, the density of charges, and the hopping distance were determined as functions of temperature and frequency. The phenoxyphenyl group has a greater influence on those parameters than the chlorophenyl group. The AC activation energies were determined at different frequencies and temperatures. The dielectric behaviors of Ph-hPQ and Ch-hPQ were investigated using the impedance spectroscopy technique. The impedance data are presented in Nyquist diagrams for different temperatures. The Ch-hPQ films have higher impedance than the Ph-hPQ films. The real dielectric constant and dielectric loss show a remarkable dependence on the frequency and temperature. The Ph-hPQ has higher dielectric constants than the Ch-hPQ.

关键词： thin films quinoline derivatives dielectrical properties correlated barrier hopping

helically symmetric equilibria for some ideal and resistive mhD plasmas with incompressible flows

在线全文

学校读者我要写书评

暂无评论

Applied mathematics(A Journal of Chinese Universities) 2023年第2期38卷 192-209页

作者： S.m.moawad O.h.El-Kalaawy h.m.Shaker mathematics and Computer Science Department Faculty of ScienceBeni-Suef UniversityBeni-SuefEgypt Future high Institute of Engineering in Fyoum Ministry of High EducationFyoumEgypt

In this paper, the problem of finding exact solutions to the magnetohydrodynamic(mhD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction method is used to obtain exact solutions for several mhD flows with nonlinear variable mach number. For resistive flows parallel to a magnetic field, the governing equilibrium equation is derived. The mhD equilibrium state of a helically symmetric incompressible flow is governed by a second-order elliptic partial differential equation(PDE) for the helical magnetic flux function. Exact solutions for the latter equation are obtained. Also, the equilibrium equations of a gravitating plasma with incompressible flow are derived.

关键词： magnetohydrodynamics helical symmetry resistivity incompressible ows exact equilibria

The synergetic effects of two CCAAT boxes in Aspergillus niger glaA gene promoter on activation of PglaA transcription

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2004年第2期47卷 139-147页

作者： WANG h. m. Genencor International Inc. 925 Page Mill Road Palo Alto California 94304 USA

EmSA and footprinting analyses have revealed that the -489—-414 bp and the -390—-345 bp (designated DC and PC respectively) upstream of the Aspergillus niger T21 glaA gene were bound by one protein factor in the A. niger T21 whole cell extract. Both DC and PC contained CCAAT pentanucleotides. The functions of DC and PC in regulation of expression of glucoamylase (GLA) were studied. CCAAT pentanucleotides were replaced with CGTAA and the mutated DNA fragments DCm and PCm lost the binding activities of protein factors in vitro. In vivo when either DC or PC was mutated or the relative orientations between them were changed on the PglaA, the transcriptional activity of PglaA decreased to a basal level. Introduction of multi-copies of DC into the original site at the PglaA in A. niger T21 decreased the expression of endogenous GLA expression and the exogenous reporter E. coli uidA gene introduced under the PglaA promoter, while having no effect on the uidA gene under the control of PgpdA. EmSA re-vealed that the levels of the specific DNA-binding protein factors in the transformants maintained the same meaning that introduction of multi-copies of DC caused the titration effect. AnghapC gene was cloned from A. niger T21 cDNA and introduced into the DC multi-copied strains. The expression of AnghapC improved the expression of the endogenous GLA and the exogenous gene controlled by PglaA. These results showed that both the CCAAT pentanucleotides were necessary for DC and PC binding to the protein factors, and the simultaneous binding of DC and PC to the protein was necessary for promoting the transcriptional activity of PglaA. AnghapC was the specific positive trans-acting protein factor binding to DC.

关键词： Aspergillus niger glucoamylase, synergetic effect, mutation analysis, multi-copy of CCAAT box, titration effect.

Dirac R-matrix calculations of photoionization cross sections of Ni Ⅻ and atomic structure data of Ni 

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第2期26卷 127-140页

作者： R T Nazirt m A Bari m Bilal S Sardar m h Nasim m Salahuddin Department of Physics and Applied mathematics Pakistan Institute of Engineering and Applied Sciences Islamabad 45650 Pakista

We performed R-matrix calculations for photoionization cross sections of the two ground state configuration 3s^23p^5（~2P_（3/2,1/2）~o） levels and 12 excited states of Ni Ⅻ using relativistic Dirac Atomic R-matrix Codes（DARC） across the photon energy range between the ionizations thresholds of the corresponding states and well above the thresholds of the last level of the Ni XIII target ion. Generally, a good agreement is obtained between our results and the earlier theoretical photoionization cross sections. moreover, we have used two independent fully relativistic GRASP and FAC codes to calculate fine-structure energy levels, wavelengths, oscillator strengths, transitions rates among the lowest 48 levels belonging to the configuration（3s^23p^4, 3s3p^5, 3p^6, 3s^23p^33d） in Ni XIII. Additionally, radiative lifetimes of all the excited states of Ni XIII are presented. Our results of the atomic structure of Ni XIII show good agreement with other theoretical and experimental results available in the literature. A good agreement is found between our calculated lifetimes and the experimental *** present results are useful for plasma diagnostic of fusion and astrophysical plasmas.

关键词： photoionization cross sections energy levels wavelengths lifetimes

Surface hardness,thermal,optical,and photon attenuation coefficients assessment for dysprosium-doped tellurite glasses

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2023年第7期41卷 1083-1090,I0004页

作者： hesham m.h.Zakaly D.E.Abulyazied h.A.Saudi B.m.Alotaibi Shams A.m.Issa Institute of Physics and Technology Ural Federal UniversityYekaterinburg620002Russia Faculty of Science Al-Azhar UniversityAssuit BranchAssuit71524Egypt Polymer Lab Department of PetrochemicalsEgyptian Petroleum Research InstituteNasr CityCairoEgypt Department of Physics Faculty of ScienceUniversity of TabukTabukSaudi Arabia Physics Department Faculty of ScienceAl-Azhar University(Girls Branch)Nasr CityCairoEgypt Department of Physics College of SciencePrincess Nourah Bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia

Using a melt-cooling process with the host glass,Dy_(2)O_(3)(1 wt%,2 wt%,3 wt%,and 4 wt%) doped tellurite glasses were produced.A(65-x)TeO_(2)-20B_(2)O_(3)-10Al_(2)O_(3)-SGeO_(2)-xDy_(2)O_(3) glass system was analyzed by Xray *** patterns have a hump at 2θ=27°-29° and no sharp peaks,indicating that all the glass samples are *** Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder *** scanning calorimetry(DSC) at 300-550℃ was used to evaluate the thermal properties of the Dy_x glass *** glass transition temperature T_g(small endothermic peak),start crystallization temperature T_x and crystallization temperature T_c can all be seen on the DSC thermogram(exothermic peaks).The UV-Vis transmittance and absorption spectra were *** optical data show that the values of E_d^(ir),E_g^(Ind) and E_U decrease as the amount of Dy_(2)O_(3)increases,indicating a narrowing of the tails due to localized states in the forbidden gap.A concentration quenching event occurs when Dy^(3+) concentrations are above a certain threshold(1%).The addition of Dy_(2)O_(3) increases glass density,while the addition of other Dy(Ⅲ) oxides increases sample *** radiation shielding values change as a consequence of density *** sample with the highest amount of Dy_(2)O_(3)(Dy_(4)) has stronger radiation shielding characteristics;hence,it is superior in terms of shielding outcomes at all energy *** Dy_x samples can be used in various forms of ionizing radiation shielding.

关键词： melt-cooling process DSC Dysprosium(Ⅲ)oxides Surface hardness Photon attenuation Rare earths