期刊文献+
共找到4,455篇文章
< 1 2 223 >
每页显示 20 50 100
High gain fiber-solid hybrid double-passing end-pumped Nd:YVO4 picosecond amplifier with high beam quality 被引量:1
1
作者 Xueyan Dong Pingxue Li +1 位作者 Shun Li Dongsheng Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第5期273-281,共9页
We propose a fiber-solid hybrid system which consists of a semiconductor saturable absorber mirror(SESAM)modelocked fiber seed with a pulse width of 10.2 ps and a repetition rate of 18.9 MHz,a two-level fiber pre-ampl... We propose a fiber-solid hybrid system which consists of a semiconductor saturable absorber mirror(SESAM)modelocked fiber seed with a pulse width of 10.2 ps and a repetition rate of 18.9 MHz,a two-level fiber pre-amplifier and a double-passing end-pumped Nd:YVO4 amplifier.In the solid-state amplifier,to enhance the gain and the extraction efficiency,a specially designed structure in which the seed light passes through the gain medium four times and makes full use of population inversion is used as the double-passing amplifier.Besides,the beam filling factor(the ratio of the seed light diameter to the pump light diameter)and the thermal lens effect of the double-passing amplifier are considered and its optical-to-optical conversion efficiency is further improved.To preserve the beam quality of the double-passing amplifier,a new method of spherical-aberration self-compensation based on the principles of geometrical optics is used and discussed.Our system achieves a maximum average power of 9.5Wat the pump power of 28W,corresponding to an optical-to-optical efficiency of 27%.And the beam quality factor M^2 reaches 1.3 at the maximum output power. 展开更多
关键词 picosecond fiber-solid hybrid double-passing amplifier high beam quality spherical-aberration self-compensation
下载PDF
Surface modification of Cu-25Cr alloy induced by high current pulsed electron beam 被引量:2
2
作者 周志明 柴林江 +3 位作者 肖志佩 涂坚 王亚平 黄伟九 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第6期1935-1943,共9页
A Cu-25Cr alloy prepared by vacuum induction melting method was treated by the high current pulsed electron beam (HCPEB) with pulse numbers ranging from 1 to 100. Surface morphologies and microstructures of the allo... A Cu-25Cr alloy prepared by vacuum induction melting method was treated by the high current pulsed electron beam (HCPEB) with pulse numbers ranging from 1 to 100. Surface morphologies and microstructures of the alloy before and after the treatment were investigated by scanning electron microscopy and X-ray diffraction. The results show that significant surface modification can be induced by HCPEB with the pulse number reaching 10. Craters with typical morphologies on the Cu-25Cr alloy surface are formed due to the dynamic thermal field induced by the HCPEB. Micro-cracks, as a unique feature, are well revealed in the irradiated Cu-25Cr specimens and attributed to quasi-static thermal stresses accumulated along the specimen surface. The amount of cracks is found to increase with the pulse number and a preference of these cracks to Cr phases rather than Cu phases is also noted. Another characteristic produced by the HCPEB is the fine Cr spheroids, which are determined to be due to occurrence of liquid phase separation in the Cu-25Cr alloy. In addition, an examination on surface roughness of all specimens reveals that more pulses will produce a roughened surface, as a result of compromising the above features. 展开更多
关键词 Cu-Cr alloy surface modification high current pulsed electron beam MICROSTRUCTURE
下载PDF
Compounded Surface Modification of ZK60 Mg Alloy by High Current Pulsed Electron Beam+Micro-plasma Oxidation 被引量:3
3
作者 高波 郝仪 +3 位作者 涂赣峰 石为喜 于福晓 李世伟 《Plasma Science and Technology》 SCIE EI CAS CSCD 2010年第1期67-70,共4页
In this study, compounded surface modification technology-high current pulsed electron beam (HCPEB) + micro-plasma oxidation (MPO) was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of... In this study, compounded surface modification technology-high current pulsed electron beam (HCPEB) + micro-plasma oxidation (MPO) was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of ZK60 Mg alloy after single MPO and HCPEB+MPO compounded treatment were investigated by SEM. The results showed that the density of the ceramic layer of HCPEB+MPO-treated ZK60 Mg alloy was improved and defects were reduced compared to that under MPO treatment alone. Surface modified layer of ZK60 Mg alloys treated by HCPEB+MPO was divided into three zones, namely the top loose ceramic zone, middle compact zone and inside HCPEB-induced melted zone. Corrosion resistance of ZK60 Mg alloy before and after the compounded surface modification was measured in a solution of 3.5% NaCl by potentiodynamic polarization curves. It was found that the corrosion current density of ZK60 Mg alloys could be reduced by about three orders of magnitude, from 311μA/cm^2 of the original sample to 0.2μA/cm^2 of the HCPEB+MPO-treated sample. This indicates the great application potential of the HCPEB+MPO compounded surface modification technology in improving the corrosion resistance of ZK60 Mg alloys in the future. 展开更多
关键词 ZK60 Mg alloy high current pulsed electron beam micro-plasma oxidation compounded surface modification corrosion resistance
下载PDF
Experimental Behavior of Partially Prestressed High Strength Concrete Beams 被引量:3
4
作者 Shady H. Salem Khalid M. Hilal +1 位作者 Tarek K. Hassan Ahmed S. Essawy 《Open Journal of Civil Engineering》 2013年第3期26-32,共7页
In the last few decades, prestressed concrete has been rapidly used in bridge engineering due to the enormous development in the construction techniques and the increasing need for long span bridges. High strength con... In the last few decades, prestressed concrete has been rapidly used in bridge engineering due to the enormous development in the construction techniques and the increasing need for long span bridges. High strength concrete has been also more widely spread than the past. It currently becomes more desirable as it has better mechanical properties and durability performance. Major defect of fully prestressed concrete is its low ductility;it may produce less alarming signs than ordinary reinforced concrete via smaller deflection and limited cracking. Therefore, partially prestressing is considered an intermediate design between the two extremes. So, combining high strength concrete with partial prestressing will result in a considerable development in the use of prestressed concrete structures regarding the economical and durability view points. This study presents the results of seven partially prestressed high strength concrete beams in flexure. The tested beams are used to investigate the influence of concrete compressive strength, prestressing steel ratio and flange width on the behavior of partially prestressed beams. The experimentally observed behaviors of all beams were presented in terms of the cracking load, ultimate load, deflection, cracking behavior and failure modes. 展开更多
关键词 PARTIALLY PRESTRESSED high Strength Concrete beamS SERVICEABILITY BEHAVIOR Failure Modes
下载PDF
High Lattice Match Growth of InAsSb Based Materials by Molecular Beam Epitaxy 被引量:2
5
作者 任洋 郝瑞亭 +4 位作者 刘思佳 郭杰 王国伟 徐应强 牛智川 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第12期133-137,共5页
High lattice match growth of InAsSb based materials on GaSb substrates is demonstrated. The present results indicate that a stable substrate temperature and the optimal flux ratios are of critical importance in achiev... High lattice match growth of InAsSb based materials on GaSb substrates is demonstrated. The present results indicate that a stable substrate temperature and the optimal flux ratios are of critical importance in achieving a homogeneous InAsSb based material composition throughout the growth period. The quality of these epilayers is assessed using a high-resolution x-ray diffraction and atomic force microscope. The mismatch between the GaSb substrate and InAsSb alloy achieves almost zero, and the rms surface roughness of InAsSb alloy achieves around 1.7A over an area of 28μm × 28μm. At the same time, the mismatches between GaSb and InAs/InAs0.73Sb0.27 superlattices (SLs) achieve approximately 100 arcsec (75 periods) and zero (300 periods), with the surface rms roughnesses of InAs/InAs0.73Sb0.27 SLs around 1.8 A (75 periods) and 2.1A (300 periods) over an area of 20 μm×20 μm, respectively. After fabrication and characterization of the devices, the dynamic resistance of the n-barrier-n InAsSb photodetector near zero bias is of the order of 10^6Ω·cm^2. At 77K, the positive-intrinsic-negative photodetectors are demonstrated in InAsSb and InAs/InAsSb SL (75 periods) materials, exhibiting fifty-percent cutoff wavelengths of 3.8μm and 5.1μm, respectively. 展开更多
关键词 INASSB as is GaSb on in high Lattice Match Growth of InAsSb Based Materials by Molecular beam Epitaxy of by
下载PDF
Improvement of Wear Resistance of Magnesium Alloy AZ91HP by High Current Pulsed Electron Beam Treatment 被引量:2
6
作者 GAOBo HAOSheng-zhi +3 位作者 ZOUJian-xin JIANGLi-min ZHOUJI-yang DONGChuang 《材料热处理学报》 EI CAS CSCD 北大核心 2004年第05B期1029-1031,共3页
Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase MgnAln is near... Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase MgnAln is nearly completely dissolved and as a result, a super-saturated solid solution forms on the re-melted surface. The microhardness is increased both in and far beyond the heat-affected zone (HAZ), reaching about 250um. Measurements on sliding wear have shown that the wear resistance of the treated samples was improved by a factor of about 2.4 as compared to the as-received sample. It is also found that the sliding wear resistance can be further improved by surface alloying with TiN. 展开更多
关键词 镁合金 HCPEB 磨损性能 AZ91HP 表面改性 高电流脉冲电子束
下载PDF
Preliminary Research Results for the Generation and Diagnostics of High Power Ion Beams on FLASH II Accelerator
7
作者 杨海亮 邱爱慈 +8 位作者 孙剑锋 何小平 汤俊萍 王海洋 李洪玉 李静雅 任书庆 欧阳小平 张国光 《Plasma Science and Technology》 SCIE EI CAS CSCD 2004年第6期2601-2604,共4页
The preliminary experimental results of the generation and diagnostics of high power ion beams on FLASH II accelerator are reported. The high-power ion beams presently are being produced in a pinched diode. The method... The preliminary experimental results of the generation and diagnostics of high power ion beams on FLASH II accelerator are reported. The high-power ion beams presently are being produced in a pinched diode. The method for enhancing the ratio of ion to electron current is to increase the electron residing time by pinching the electron flow. Furthermore, electron beam pinching can be combined with electron reflexing to achieve ion beams with even higher efficiency and intensity. The anode plasma is generated by anode foil bombarded with electron and anode foil surface flashover. In recent experiments on FLASH II accelerator, ion beams have been produced with a current of 160 kA and an.energy of 500 keV corresponding to an ion beam peak power of about 80 GW. The ion number and current of high power ion beams were determined by monitoring delayed radioactivity from nuclear reactions induced in a 12C target by the proton beams. The prompt 7-rays and diode bremsstrahlung X-rays were measured with a PIN semi-conductor detector and a plastic scintillator detector. The current density distribution of ion beam were measured with a biased ion collector array. The ion beams were also recorded with a CR-39 detector. 展开更多
关键词 high power ion beam pinched diode nuclear activation technique
下载PDF
Improvement of wear resistance of AZ31 and AZ91HP by high current pulsed electron beam treatment 被引量:1
8
作者 高波 郝胜智 +1 位作者 董闯 涂赣峰 《中国有色金属学会会刊:英文版》 EI CSCD 2005年第5期978-984,共7页
The surface modification of magnesium alloys (AZ31 and AZ91HP) was studied by a high current pulsed electron beam(HCPEB). The results show that the cross-sectional microhardness of treated samples increases not only i... The surface modification of magnesium alloys (AZ31 and AZ91HP) was studied by a high current pulsed electron beam(HCPEB). The results show that the cross-sectional microhardness of treated samples increases not only in the heat affected zone(HAZ), but also beyond HAZ, reaching over 250μm. This is due to the action of quasi-static thermal stress and the shock thermal stress wave with materials, which result in its fast deformation on the surface layer and so increases microhardness. For the AZ91HP alloy, a nearly complete dissolution of the intermetallic phase Mg_ 17Al_ 12 is observed, and a super-saturated solid solution forms on the re-melted surface, which is due to the solute trapping effect during the fast solidification process. Measurements on sliding wear show that wear resistance is improved by approximately 5.6 and 2.4 times for the AZ31 and AZ91HP respectively, as compared with as-received samples. 展开更多
关键词 铝合金 磨损阻力 脉冲处理 电子波 强度 密度 金属相
下载PDF
Characterizing modified surface layer of 316L stainless steel treated by high current pulsed electron beam
9
作者 GROSDIDIER Thierry 《Rare Metals》 SCIE EI CAS CSCD 2007年第S1期61-66,共6页
High current pulsed electron beam(HCPEB) is now developing as a useful tool for surface modification of materials.When concentrated electron flux transferring its energy into the surface layer of target material withi... High current pulsed electron beam(HCPEB) is now developing as a useful tool for surface modification of materials.When concentrated electron flux transferring its energy into the surface layer of target material within a short pulse time,coupled thermal and stress processes would lead to the formation of metastalbe microstructure with improved properties.In the present work,HCPEB treatment of 316L stainless steel(SS) was carried out and the microstructural changes in modified surface layer were characterized with optical microscopy,X-ray diffractometry and electron backscatter diffractometry(EBSD) techniques.The corrosion resistance of modified surface was measured in a 5wt.% salt solution.The evolution regularity of surface craters and grain refinement effect,as well as the preferred orientation of(111) crystal plane occurring in the HCPEB treatment under different working parameters were discussed along with their influence on corrosion resistance. 展开更多
关键词 high current pulsed electron beam surface modification 316L stainless steel MICROSTRUCTURE CORROSION
下载PDF
Microstructure and properties of Nb/Ta multilayer films irradiated by a high current pulse electron beam
10
作者 马欣新 郭光伟 +2 位作者 唐光泽 孙明仁 王黎钦 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第5期407-411,共5页
Nb/Ta multilayer films deposited on Ti6A14V substrate with Nb and Ta monolayer thicknesses of 30 nm, 120 nm, and 240 nm were irradiated by a high current pulse electron beam (HCPEB) to prepare Nb-Ta alloyed layers. ... Nb/Ta multilayer films deposited on Ti6A14V substrate with Nb and Ta monolayer thicknesses of 30 nm, 120 nm, and 240 nm were irradiated by a high current pulse electron beam (HCPEB) to prepare Nb-Ta alloyed layers. The mi- crostructure and the composition of the outmost surface of melted alloyed layers were investigated using a transmission electron microscope (TEM) equipped with an X-ray energy dispersive spectrometer (EDS) attachment. The Ta content of the alloyed surface layer prepared from the monolayer of thickness 30 nm, 120 nm, and 240 nm was- 27.7 at.%, 6.37 at.%, and 0 at.%, respectively. It was found that the Ta content in the alloyed layer plays a dominant role in the microstructure of the films. The hardness and the wear rate of the alloyed layers decrease with the increasing content of Ta in the surface laver. 展开更多
关键词 Nb-Ta alloyed layer multilayer film high current pulse electron beam wear resistance
下载PDF
High-energy-density electron beam generation in ultra intense laser-plasma interaction 被引量:1
11
作者 Jianxun LIU Yanyun MA +7 位作者 Jun ZHAO Tongpu YU Fuqiu SHAO Hongbin ZHUO Longfei GAN Guobo ZHANG Yuan ZHAO Jingkang YANG1] 《Plasma Science and Technology》 SCIE EI CAS CSCD 2017年第1期1-6,共6页
By using a two-dimensional particle-in-cell simulation,we demonstrate a scheme for highenergy-density electron beam generation by irradiating an ultra intense laser pulse onto an aluminum(Al) target.With the laser h... By using a two-dimensional particle-in-cell simulation,we demonstrate a scheme for highenergy-density electron beam generation by irradiating an ultra intense laser pulse onto an aluminum(Al) target.With the laser having a peak intensity of 4×10^23W cm^-2,a high quality electron beam with a maximum density of 117 nc and a kinetic energy density up to8.79×10^18J m^-3 is generated.The temperature of the electron beam can be 416 Me V,and the beam divergence is only 7.25°.As the laser peak intensity increases(e.g.,1024 W cm^-2),both the beam energy density(3.56×10^19J m^-3) and the temperature(545 Me V) are increased,and the beam collimation is well controlled.The maximum density of the electron beam can even reach 180 nc.Such beams should have potential applications in the areas of antiparticle generation,laboratory astrophysics,etc. 展开更多
关键词 ultra intense laser PLASMA high-energy-density electron beam
下载PDF
Generating Proton Beams Exceeding 10 MeV Using High Contrast 60TW Laser 被引量:1
12
作者 Yi-Xing Geng Qing-Liao +14 位作者 Yin-Ren Shou Jun-Gao Zhu Xiao-Han Xu Min-Jian Wu Peng-Jie Wang Dong-Yu Li Tong-Yang Rong-Hao Hu Da-Hui Wang Yan-Ying Zhao Wen Jun Ma Hai-Yang Lu Zhong-Xi Yuan Chen-Lin Xue-Qing Yan 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第9期28-32,共5页
A prototype of a laser driven proton accelerator is built at Peking University. Protons exceeding IOMeV are accelerated from micrometer-thick aluminum targets irradiated by tightly focused laser pulse with 1.8 J energ... A prototype of a laser driven proton accelerator is built at Peking University. Protons exceeding IOMeV are accelerated from micrometer-thick aluminum targets irradiated by tightly focused laser pulse with 1.8 J energy and 30fs duration. The beam energy spectrum and charge distribution are measured by a Thomson parabola spectrometer and radiochromic fihn stacks. The sensitivity of proton cut-off energy to the focusing of the laser beam, the pulse duration, and the foil thickness are systematically investigated in the experiments. Stable proton beams have been produced with an optimized parameter set, providing a cornerstone for the future applications of laser accelerated protons. 展开更多
关键词 Generating Proton beams Exceeding 10 MeV Using high Contrast 60TW Laser
下载PDF
Numerical study on the thermo-stress of ZrO_2 thermal barrier coatings by high-intensity pulsed ion beam irradiation 被引量:1
13
作者 吴迪 刘臣 +1 位作者 朱小鹏 雷明凯 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第11期4976-4980,共5页
This paper studies numerically the thermo-mechanical effects of ZrO2 thermal barrier coatings (TBCs) irradiated by a high-intensity pulsed ion beam in consideration of the surface structure. Taking the deposited ene... This paper studies numerically the thermo-mechanical effects of ZrO2 thermal barrier coatings (TBCs) irradiated by a high-intensity pulsed ion beam in consideration of the surface structure. Taking the deposited energy of ion beams in TBCs as the source term in the thermal conduction equation, the distribution of temperature in TBCs was simulated. Then, based on the distribution, the evolution of thermal stress was calculated by the finite element method. The results show that tensile radial stress formed at the valley of TBC surfaces after irradiation by HIPIB. Therefore, if cracks happen, they must be at valleys instead of peaks. As for the stress waves, no matter whether through peak or valley position, tensile and compressive stresses are present alternately inside TBCs along the depth direction, and the strength of stress decreases with time. 展开更多
关键词 high-intensity pulsed ion beam ZrO2 TBCs stress field numerical method
下载PDF
The Effect of Intensity Pulsed Ion Beam Irradiation on Wear Resistance of High-speed Steel 被引量:1
14
作者 MEIXian-xiu HAOSheng-zhi MATeng-cai WANGYing-min LIUZhen-min 《材料热处理学报》 EI CAS CSCD 北大核心 2004年第05B期1049-1052,共4页
The structural and phase transformations occurring in the near-surface layers of pre-quenched W6Mo5Cr4V2 high-speed steel (HSS) subjected to intensity pulsed ion beam (IPIB) melting have been investigated. The effect ... The structural and phase transformations occurring in the near-surface layers of pre-quenched W6Mo5Cr4V2 high-speed steel (HSS) subjected to intensity pulsed ion beam (IPIB) melting have been investigated. The effect of IPIB irradiation on wear resistance of the HSS has also been studied. The IPIB consists mainly of Cn+(30%)^0 H+(70%), with a high beam current density of 80A/cm2, acceleration voltage of 250kV, pulse duration of 70 ns. Samples were bombarded with 1, 3, 5 pulses respectively. It has been revealed that after IPIB irradiation the initial martensite in the near-surface layer of HSS changed into austenite and produced residual stresses by using electron microscopy and X-ray diffraction. Redistribution and interlace of dislocations in the irradiated samples were generated under the impact of shock wave. With increasing pulse times gradual liquid-phase dissolution of M6C carbide particles occurs in the near-surface layer and produces nanocrystalline MC. This process results in the decrease of martensite crystal (a-phase) and increase of austenite (y-phase) content and the dispersed carbide. Wear resistance of the HSS is improved by a factor of 2, which is explained by the formation of metastable phases such nanocrystal and residual stresses and the redistribution and interlace of dislocations. 展开更多
关键词 高速钢 磨损性能 强脉冲离子束 热处理
下载PDF
Influence of high-intensity pulsed ion beams irradiation on oxidation behavior of 316L stainless steel at 700℃ 被引量:2
15
作者 王旭 王兰芳 +2 位作者 祝美丽 张俊善 雷明凯 《中国有色金属学会会刊:英文版》 CSCD 2006年第B02期676-680,共5页
316L stainless steel samples, as a widespread used material, were irradiated with HIPIB at the beam parameters of ion energy 300 keV, current density 100, 200 and 300 A/cm2, shot number 10 and pulse duration 75 ns. Th... 316L stainless steel samples, as a widespread used material, were irradiated with HIPIB at the beam parameters of ion energy 300 keV, current density 100, 200 and 300 A/cm2, shot number 10 and pulse duration 75 ns. The surface morphology and the phase structure in the near surface region of original and treated samples were analyzed with scanning electron microscopy (SEM) and X-ray diffractometry (XRD). It is shown that the HIPIB irradiation can smooth the surface of the samples, and the preferred orientation is present in the surface layer of irradiated coupons. The influence of HIPIB irradiation on the oxidation behavior of 316L stainless steel at 700℃for up to 100 h was investigated. Electron probe microanalysis (EPMA) was used to study the distribution of elements in the oxidation products. It is found that the oxidation behavior of the irradiated coupons depends greatly on the ion current density of HIPIB. HIPIB irradiation with ion current density of 100 A/cm2 slightly reduces the oxidation rate with respect to the unirradiated coupon. The improvement of the oxidation resistance can be attributed to more oxide of Cr that forms on the surface of the irradiated coupons. In contrast, HIPIB irradiation with ion current density of 200 or 300 A/cm2 is proved to be detrimental, causing a higher oxidation rate. 展开更多
关键词 316L不锈钢 高强度脉冲离子束 辐照 表面改性 高温氧化
下载PDF
A fast emittance measurement unit for high intensity DC beam
16
作者 张艾霖 任海涛 +7 位作者 彭士香 张滔 徐源 张景丰 温佳美 武文斌 郭之虞 陈佳洱 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第2期446-449,共4页
A combined unit, which has the ability to measure the current and emittance of the high intensity direct current(DC)ion beam, is developed at Peking University(PKU). It is a multi-slit single-wire(MSSW)-type bea... A combined unit, which has the ability to measure the current and emittance of the high intensity direct current(DC)ion beam, is developed at Peking University(PKU). It is a multi-slit single-wire(MSSW)-type beam emittance meter combined with a water-cooled Faraday Cup, named high intensity beam emittance measurement unit-6(HIBEMU-6). It takes about 15 seconds to complete one measurement of the beam current and its emittance. The emittance of a 50-mA@50-kV DC proton beam is measured. 展开更多
关键词 emittance measurement high intensity DC beam MSSW
下载PDF
Electromagnetic Resonance of Astigmatic Gaussian Beam to the High Frequency Gravitational Waves
17
作者 仲元红 李瑾 +1 位作者 周瑶 雷绮仑 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第10期11-14,共4页
The high frequency gravitational waves (around lOS-lO12 Hz) could interact with a specially designed electro- magnetic resonance system. It is found that the power of transverse perturbative photon flux (PPF) of a... The high frequency gravitational waves (around lOS-lO12 Hz) could interact with a specially designed electro- magnetic resonance system. It is found that the power of transverse perturbative photon flux (PPF) of an electromagnetic resonance system can be improved significantly by virtue of an astigmatic Caussian beam. Cor- respondingly the signal-to-noise ratio (SNR) would also be improved. When the eccentric ratio of waist satisfying w0x : w0y 〉 1, the peak value of signal photon flux could be raised by 2-4 times with typical systematic parameters, while the background photon flux would be depressed. Therefore, the ratio of transverse PPF to background photon flux (i.e., SNR) can be further improved 3-8 times with dimensionless amplitude of relic gravitational wave ht = 10-36. 展开更多
关键词 of on IS in PPF Electromagnetic Resonance of Astigmatic Gaussian beam to the high Frequency Gravitational Waves
下载PDF
Microstructures and Properties of 550 MPa Grade High Strength Thin-walled H-beam Steel 被引量:2
18
作者 CHEN Jiping KANG Yonglin +2 位作者 QIAN Jianqing LI Shengzhi QIAN Haifan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第6期1217-1222,共6页
The microstructures and mechanical properties of 550 MPa grade lightweight high strength thin-walled H-beam steel were experimentally studied. The experimental results show that the microstructure of the air-cooled H-... The microstructures and mechanical properties of 550 MPa grade lightweight high strength thin-walled H-beam steel were experimentally studied. The experimental results show that the microstructure of the air-cooled H-beam steel sample is consisted of ferrite, pearlite and a small amount of granular bainites as well as fine and dispersive V(C,N) precipitates. The microstructure of the water-cooled steel sample is consisted of ferrite and bainite as well as a small amount of fine pearlites. The microstructure of the water-cooled sample is finer than that of the air-cooled sample with the average intercept size of the surface grains reaching to 3.5 gna. The finish rolling temperature of the thin-walled high strength H-beam steel is in the range of 750 ~C-850 ~C. The lower the finish rolling temperature and the faster the cooling rate, the finer the ferrite grains, the volume fraction of bainite is increased through water cooling process. Grain refinement strengthening and precipitation strengthening are used as major strengthening means to develop 550 MPa grade lightweight high strength thin- walled H-beam steel. Vanadium partially soluted in the matrix and contributes to the solution strengthening. The 550 MPa grade high-strength thin-walled H-beam steel could be developed by direct air cooling after hot rolling to fully meet the requirements of the target properties. 展开更多
关键词 H-beam steel high strength thin-walled vanadium-nitrogen microalloying microstructure and mechanical property strengthening mechanism
下载PDF
THE ASYMPTOTIC PROPERTIES OF HIGH FREQUENCIES FOR BARS,BEAMS AND MEMBRANES
19
作者 姬建军 胡奎 王大钧 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1989年第12期1187-1193,共7页
In this paper, a uniform analysis of the asymptotic properties of high frequencies of non-uniform bars, beams and circular membranes is given by using perturbation method, and the ease of discontinuous physical parame... In this paper, a uniform analysis of the asymptotic properties of high frequencies of non-uniform bars, beams and circular membranes is given by using perturbation method, and the ease of discontinuous physical parameters is also discussed. 展开更多
关键词 high MODE THE ASYMPTOTIC PROPERTIES OF high FREQUENCIES FOR BARS beamS AND MEMBRANES
下载PDF
Flexural Behaviour of High-Strength Steel Fiber-Reinforced Concrete Beams
20
作者 钱春香 IndubhushanPatnaikuni 《Journal of Southeast University(English Edition)》 EI CAS 1996年第2期137-144,共8页
This paper presents the research results of twelve high strength concrete beams reinforced with steel fibers and bars. Fiber type I and II reduce the deflection by more than 25% and increase the ultimate load by abou... This paper presents the research results of twelve high strength concrete beams reinforced with steel fibers and bars. Fiber type I and II reduce the deflection by more than 25% and increase the ultimate load by about 10% compared to high strength concr 展开更多
关键词 high strength CONCRETE beam STEEL FIBER deflection crack DUCTILITY
下载PDF
上一页 1 2 223 下一页 到第
使用帮助 返回顶部