Our gosl was to develop and experimentally validate a polarization-interferene method for phsae scanning of laser speckle fields generated by diffuse layers of birefringent biological tissues.This method isolates and ...Our gosl was to develop and experimentally validate a polarization-interferene method for phsae scanning of laser speckle fields generated by diffuse layers of birefringent biological tissues.This method isolates and uses new diagnostic parameters related to the"phsse WAvEs of local depolarization".We combined polarization-interferenæregistration with phase scanning of complex amplitude distributions in diffuse Laser speckle fields to detect phase waves of local depolarization in birefringent fibrillar networks of biological tisue and messure their modulation depth.This eppгоsch led to the discovery of new criteria for differentiating verious necrotic changes in diffuse histological samples of myocardial tisue from decmsed individuals with"ischemic heart disase(IHD)--cute coronary insufficiency(ACT)",even in the presænce of a high level of depolarized bckground.To evaluate the degree of necrotic changes in the optical anisotropy of difuse myocardial Layers,a new quantitative parameter--modulation depth of local depolarization wave fluctustions-has been proposed.Using this approsch,for the first time,differentiation of diffuse myocardial samples from decessed individuals with IHD and ACI was achieved witha very good 90.45%and outstanding aocuracy of 95.2%.展开更多
Phase is one of the most important parameters of electromagnetic waves. It is the phase distribution that determines the propagation, reflection, refraction, focusing, divergence, and coupling features of light, and f...Phase is one of the most important parameters of electromagnetic waves. It is the phase distribution that determines the propagation, reflection, refraction, focusing, divergence, and coupling features of light, and further affects the intensity distribution. In recent years, the designs of surface plasmon polariton （SPP） devices have mostly been based on the phase modulation and manipulation. Here we demonstrate a phase sensitive multi-parameter heterodyne scanning near-field opti- cal microscope （SNOM） with an aperture probe in the visible range, with which the near field optical phase and amplitude distributions can be simultaneously obtained. A novel architecture combining a spatial optical path and a fiber optical path is employed for stability and flexibility. Two kinds of typical nano-photonic devices are tested with the system. With the phase-sensitive SNOM, the phase and amplitude distributions of any nano-optical field and localized field generated with any SPP nano-structures and irregular phase modulation surfaces can be investigated. The phase distribution and the interference pattern will help us to gain a better understanding of how light interacts with SPP structures and how SPP waves generate, localize, convert, and propagate on an SPP surface. This will be a significant guidance on SPP nano-structure design and optimization.展开更多
This paper reports the theoretical study of combining Z-scan technique with Gauss-Bessel （GB） beams beside a phase object （PO） to measure the third-order nonlinear susceptibility components. By using this method, ...This paper reports the theoretical study of combining Z-scan technique with Gauss-Bessel （GB） beams beside a phase object （PO） to measure the third-order nonlinear susceptibility components. By using this method, the sign of refractive index which depends on the shape of the close aperture Z-scan curve can be easily determined. Meanwhile, the magnitude of nonlinear coefficients can also be deduced by theoretical fit. The proposed method is advantageous for high sensitivity and imposes a lower stress in the cases of fragile materials, since small pulse energy is enough for the measurement of nonlinear coefficients. Predictions of the models are compared with Gaussian Z-scan measurement and GB Z-scan measurement. By using GB beams with a PO, the sensitivity of Z-scan measurements is found to be a factor of over 60 times greater than for Gaussian beams and 2 times greater than for Gaussian-Bessel beams.展开更多
Two novel phase transition materials,[C9H20N2][Na（BF4）3]（1） and[C9H20N2][（PF6）2]（2）,were synthesized based on 1-isopropyl-1,4-diazabicyclo[2.2.2]octan-1-ium with sodium tetrafluoroborate and hexafluorophosphor...Two novel phase transition materials,[C9H20N2][Na（BF4）3]（1） and[C9H20N2][（PF6）2]（2）,were synthesized based on 1-isopropyl-1,4-diazabicyclo[2.2.2]octan-1-ium with sodium tetrafluoroborate and hexafluorophosphoric acid,respectively.Differential scanning calorimetry measurements detected that 1 and 2 underwent reversible phase transitions,which were confirmed by dielectric measurements.Single crystal X-ray diffraction data suggested that compound 1 changed from a high temperature phase with a space group of P6_3 to a low temperature one with a space group of P21/c,and that compound 2transformed from the space group of Pbca at room temperature to P21/c at low temperature.Formation of hydrogen bonds and distortion of l,4-diazabicyclo[2.2.2]octane rings may drive the transitions.展开更多
The effect of Sm-rich liquid phase （Sm2Co3） on magnetic properties and microstructure of 2：17-type Sin-Co magnet was studied. Three phases existed in liquid phase ingot, and took on white, dark grey and grey, respe...The effect of Sm-rich liquid phase （Sm2Co3） on magnetic properties and microstructure of 2：17-type Sin-Co magnet was studied. Three phases existed in liquid phase ingot, and took on white, dark grey and grey, respectively. It was found that the composition of the grey area was similar to the nominal one. Our results indicated that the optimal composition was obtained at 3 wt.% liquid phase added, and the magnetic properties were B^I 1.58 kGs, Hci〉26 kOe, （BH）m=29.51 MGOe. Br increased by 3%, Hci was 13 times larger, and （B/-/）m was 6 times bigger than none liquid phase magnets. Moreover, with the aging time decreasing from 20 to 8 h, the squareness of the demagnetization curves got better, while the coercivity of the samples decreased. It revealed that Sm（Co,Cu）5 phase also precipitated at particle boundaries. It maybe also enhanced the coercivity.展开更多
Two different kinds of experimental techniques were used to in-situ study the austenite formation during intercritical annealing in C-Mn dual phase steel. The microstructure evolution was observed by confocal laser sc...Two different kinds of experimental techniques were used to in-situ study the austenite formation during intercritical annealing in C-Mn dual phase steel. The microstructure evolution was observed by confocal laser scanning microscope, and the austenite isothermal and non-isothermal transformation kinetics were studied by dilatometry. The results indicate that banded structure is produced for the reason of composition segregation and the competition between recrystallization and phase transformation. Austenite prefers to nucleate not only at ferrite/ferrite grain boundaries, but also inside the grains of ferrite.Furthermore, the austenitizing process is accomplished mainly via migration of the existing austenite/ferrite interface rather than nucleation of new grains. The incubation process can be divided into two stages which are controlled by carbon and manganese diffusion, respectively. During the incubation process, the nucleation rate of austenite decreases, and austenite growth changes from two-dimensional to one-dimensional. The partitioning coefficient, defined as the ratio of manganese content in the austenite to that in the adjacent ferrite, increases with increasing soaking time.展开更多
The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy disper...The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy dispersive X-ray spectroscopy (EDX). The galvanic corrosion of the Q-phase/Al couple was found to be dependent on pH and immersion time. Current density maps obtained by SVET shows that the anodic oxidation processes emerge from Al in a localized manner in pH 2 and 6 solutions but is initiated in a uniform manner in pH 13 solution, whereas, the cathodic processes are more homogeneously distributed over the Q-phase at pH 2.6 and 13. It is seen that the Q-phase remains cathodic in the Q-phase/Al couple in acidic, neutral and alkaline solutions indicating that the galvanic polarity of the Q-phase is independent of pH. The effect of the galvanic corrosion was largest at pH 2 and 13 compared to pH 6. The pH map obtained by SIET indicates that the galvanic activity of the Q-phase/Al couple proceeds via heavy alkalization of the Q-phase surface with the generation of appreciable amounts of OH~ ions. The enrichment of Cu indicated by EDX is responsible for the observed cathodic activity of the Q-phase in the Q-phase/Al couple.展开更多
A phased array radar seeker（PARS） must be able to effectively decouple body motion and accurately extract the line-of-sight（LOS） rate for target missile tracking.In this study,the realtime two-channel beam pointin...A phased array radar seeker（PARS） must be able to effectively decouple body motion and accurately extract the line-of-sight（LOS） rate for target missile tracking.In this study,the realtime two-channel beam pointing error（BPE） compensation method of PARS for LOS rate extraction is designed.The PARS discrete beam motion principium is analyzed,and the mathematical model of beam scanning control is finished.According to the principle of the antenna element shift phase,both the antenna element shift phase law and the causes of beam-pointing error under phantom-bit conditions are analyzed,and the effect of BPE caused by phantom-bit technology（PBT） on the extraction accuracy of the LOS rate is examined.A compensation method is given,which includes coordinate transforms,beam angle margin compensation,and detector dislocation angle calculation.When the method is used,the beam angle margin in the pitch and yaw directions is calculated to reduce the effect of the missile body disturbance and to improve LOS rate extraction precision by compensating for the detector dislocation angle.The simulation results validate the proposed method.展开更多
InAsSb epilayers with a cutoff wavelength of 4.8 μm have been successfully grown on InAs substrates by one-step liquid phase epitaxy （LPE） technology. The epilayers were characterized by X-ray diffraction （XRD）, ...InAsSb epilayers with a cutoff wavelength of 4.8 μm have been successfully grown on InAs substrates by one-step liquid phase epitaxy （LPE） technology. The epilayers were characterized by X-ray diffraction （XRD）, Fourier transform infrared （PTIR） transmittance measurements and scanning electron microscopy （SEM）. The influence of different growth conditions on the optical and structural properties of the materials was studied. The results revealed that the good crystalline quality, mirror smooth surface and flat interface of InAsSb epilayers were achieved. They benefited from optimized growth conditions, i.e., sufficient homogeneity of the growth melt and a very slow cooling rate.展开更多
Structural phase transitions of Zn4Sb3 and its substitutional compounds （Zn0.98M0.02）4Sb3 （M = Al, Ga and In） are investigated by electrical transport measurement and differential scanning calorimetry below room t...Structural phase transitions of Zn4Sb3 and its substitutional compounds （Zn0.98M0.02）4Sb3 （M = Al, Ga and In） are investigated by electrical transport measurement and differential scanning calorimetry below room temperature. The results indicate that both β→α and α→α′ phase transitions of Zn4Sb3 are reversible and exothermic processes, which may be explained as that both the transitions originate from the ordering of the disordered interstitial Zn and vacancies in regular sizes. The derived activation energies of β→α and α→α′ phase transition processes for Zn4Sb3 are E1 = 3.9 eV and E2 = 4.1 eV, respectively. Although no remarkable influence on activation energy E2 is observed after A1 doping, A1 substitution for Zn causes E1 to increase to 4.6 eV, implying its suppression of β←→α transition to a great extent. Moreover, it is found that both β←→α and α←→α′ transitions are completely prohibited by substitution of either In or Ga for Zn in Zn4Sb3. The underlying mechanisms for these phenomena are discussed.展开更多
In this study, a two-step heating process is introduced for transient liquid phase ( TLP) diffusion bonding fo r sound joints with T91 heat resistant steels. At first, a short-time higher temperature heating ...In this study, a two-step heating process is introduced for transient liquid phase ( TLP) diffusion bonding fo r sound joints with T91 heat resistant steels. At first, a short-time higher temperature heating step is addressed to melt the interlayer, followed by the second step to complete isothermal solidification at a low temperature. The most critical feature of our new method is producing a non-planar interface at the T9/ heat resistant steels joint. We propose a transitional liquid phase bonding of T91 heat resistant steels by this approach. Since joint microstructures have been studied, we tested the tensile strength to assess joint mechanical property. The result indicates that the solidified bond may contain a primary solid-solution, similar composition to the parent metal and free from precipitates. Joint tensile strength of the joint is not lower than parent materials. Joint bend's strengths are enhanced due to the higher metal-to-metal junction producing a non-planar bond lines. Nevertheless, the traditional transient liquid phase diffusion bonding produces planar ones. Bonding parameters of new process are 1 260 °C for 0. 5 min and 1 230 °C fo r 4 min.展开更多
An investigation was made of the influence of Zr additive on the high temperature phase trans- formations,martensitic forward/reverse transformations,and shape memory effect of Cu-Zn-Al base alloys by means of differe...An investigation was made of the influence of Zr additive on the high temperature phase trans- formations,martensitic forward/reverse transformations,and shape memory effect of Cu-Zn-Al base alloys by means of differential scanning calorimetry(DSC),X-ray diffraction and TEM.It was found that an addition of 0.35 wt-% Zn could effectively inhibit the precipitation of α and γ phases and hence promote the order-martensitic transformations β_2→DO_3→18RM,thus resulting in a minimum activation energy of the martensitic trans- formation and narrow temperature ranges(M_s-M_f)and(A_s-A_f);the alloy so obtained pos- sessed smooth and mobile martensite intervariant interfaces,therefore showing the best shape memory effect.展开更多
Aberration-corrected scanning transmission electron microscopy was employed to investigate the microstructures and secondary phases in LaBaCo2O5.5＋δ（LBCO） thin films grown on SrTiO3 （STO） substrates. The as-grow...Aberration-corrected scanning transmission electron microscopy was employed to investigate the microstructures and secondary phases in LaBaCo2O5.5＋δ（LBCO） thin films grown on SrTiO3 （STO） substrates. The as-grown films showed an epitaxial growth on the substrates with atomically sharp interfaces and orientation relationships of [100]LBCO//[100]STO and （001）LBCO//（001）STO. Secondary phases were observed in the films, which strongly depended on the sample fabrication conditions. In the film prepared at a temperature of 900 ℃, nano-scale CoO pillars nucleated on the substrate, and grew along the [001] direction of the film. In the film grown at a temperature of 1000 ℃, isolated nano-scale C0304 particles appeared, which promoted the growth of {111 } twinning structures in the film. The orientation relationships and the interfaces between the secondary phases and the films were illustrated, and the growth mechanism of the film was discussed.展开更多
Differential scanning calorimetry (DSC) measurements of 37 polycrystalline LaH x (2 0<x <3 0) were performed in this work. Samples were synthesized by a direct reaction of a metal with hydrogen at temperat...Differential scanning calorimetry (DSC) measurements of 37 polycrystalline LaH x (2 0<x <3 0) were performed in this work. Samples were synthesized by a direct reaction of a metal with hydrogen at temperatures higher than 250 ℃ (depending on the final composition). DSC measurements were performed in the temperature range of 110～400 K. For the samples in the range of 2 13< x <2 40 single DSC peaks were detected. In the composition range x >2 45 much more complicated DSC signals (double, triple etc. peaks) were observed which some of them were up to 4 phase transformations. Based on these measurements and carried out on high purity samples and supported by high accuracy hydrogen content determination, a new T-x phase diagram for 110< T <400 K and 2< x <3(LaH x ) was proposed. This new phase diagram shows an up to now unknown complexity phase relationships with the existence of at least 11 of phases at T <400 K.展开更多
The CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO phase diagram was investigated in the CaO low region (<40 mol.%). CaCl<sub>2</sub>-CaF<sub>2</sub> and CaCl<sub>2</s...The CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO phase diagram was investigated in the CaO low region (<40 mol.%). CaCl<sub>2</sub>-CaF<sub>2</sub> and CaCl<sub>2</sub>-CaO binary diagrams, constituting the ternary system, were first studied by Differential Scanning Calorimetry (DSC) measurements and X-Ray Diffraction (XRD) characterization;a good agreement was obtained between the phase diagram models calculated with FactSage®software (FTsalt database) and present experimental data. As the CaF<sub>2</sub>-CaO liquidus could not be measured by DSC due to the high melting temperature, this diagram was calculated using FTsalt database combined with FToxid database of FactSage<sup>®</sup> software. The ternary phase diagram was obtained by calculations and exhibits an eutectic at the composition CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO (78.2-15.7-6.1 mol.%) melting at 637°C, and five peritectic points. Measurements of relevant vertical cross-sections for three CaCl<sub>2</sub>-CaF<sub>2</sub> compositions (50-50, 40-60 and 30-70 mol.%) up to 18 mol.% CaO are in agreement with the ternary phase diagram model. For each section, the liquidus temperature is constant up to around 11 mol.% CaO and then sharply increases. Moreover, an increase of CaF<sub>2</sub> content in CaCl<sub>2</sub>-CaF<sub>2</sub> melt leads to a decrease of the CaO solubility in isothermal condition.展开更多
A feature extraction method was proposed to sectorial scan image of Ti-6Al-4V electron beam welding seam based on principal component analysis to solve problem of high-dimensional data resulting in timeconsuming in de...A feature extraction method was proposed to sectorial scan image of Ti-6Al-4V electron beam welding seam based on principal component analysis to solve problem of high-dimensional data resulting in timeconsuming in defect recognition. Seven features were extracted from the image and represented 87. 3% information of the original data. Both the extracted features and the original data were used to train support vector machine model to assess the feature extraction performance in two aspects: recognition accuracy and training time. The results show that using the extracted features the recognition accuracy of pore,crack,lack of fusion and lack of penetration are 93%,90.7%,94.7% and 89.3%,respectively,which is slightly higher than those using the original data. The training time of the models using the extracted features is extremely reduced comparing with those using the original data.展开更多
文摘Our gosl was to develop and experimentally validate a polarization-interferene method for phsae scanning of laser speckle fields generated by diffuse layers of birefringent biological tissues.This method isolates and uses new diagnostic parameters related to the"phsse WAvEs of local depolarization".We combined polarization-interferenæregistration with phase scanning of complex amplitude distributions in diffuse Laser speckle fields to detect phase waves of local depolarization in birefringent fibrillar networks of biological tisue and messure their modulation depth.This eppгоsch led to the discovery of new criteria for differentiating verious necrotic changes in diffuse histological samples of myocardial tisue from decmsed individuals with"ischemic heart disase(IHD)--cute coronary insufficiency(ACT)",even in the presænce of a high level of depolarized bckground.To evaluate the degree of necrotic changes in the optical anisotropy of difuse myocardial Layers,a new quantitative parameter--modulation depth of local depolarization wave fluctustions-has been proposed.Using this approsch,for the first time,differentiation of diffuse myocardial samples from decessed individuals with IHD and ACI was achieved witha very good 90.45%and outstanding aocuracy of 95.2%.
基金supported by the National Natural Science Foundation of China(Grant Nos.61177089,61227014,and 60978047)
文摘Phase is one of the most important parameters of electromagnetic waves. It is the phase distribution that determines the propagation, reflection, refraction, focusing, divergence, and coupling features of light, and further affects the intensity distribution. In recent years, the designs of surface plasmon polariton （SPP） devices have mostly been based on the phase modulation and manipulation. Here we demonstrate a phase sensitive multi-parameter heterodyne scanning near-field opti- cal microscope （SNOM） with an aperture probe in the visible range, with which the near field optical phase and amplitude distributions can be simultaneously obtained. A novel architecture combining a spatial optical path and a fiber optical path is employed for stability and flexibility. Two kinds of typical nano-photonic devices are tested with the system. With the phase-sensitive SNOM, the phase and amplitude distributions of any nano-optical field and localized field generated with any SPP nano-structures and irregular phase modulation surfaces can be investigated. The phase distribution and the interference pattern will help us to gain a better understanding of how light interacts with SPP structures and how SPP waves generate, localize, convert, and propagate on an SPP surface. This will be a significant guidance on SPP nano-structure design and optimization.
基金supported by the National Natural Science Fundation of China (Grant No. 90922007)
文摘This paper reports the theoretical study of combining Z-scan technique with Gauss-Bessel （GB） beams beside a phase object （PO） to measure the third-order nonlinear susceptibility components. By using this method, the sign of refractive index which depends on the shape of the close aperture Z-scan curve can be easily determined. Meanwhile, the magnitude of nonlinear coefficients can also be deduced by theoretical fit. The proposed method is advantageous for high sensitivity and imposes a lower stress in the cases of fragile materials, since small pulse energy is enough for the measurement of nonlinear coefficients. Predictions of the models are compared with Gaussian Z-scan measurement and GB Z-scan measurement. By using GB beams with a PO, the sensitivity of Z-scan measurements is found to be a factor of over 60 times greater than for Gaussian beams and 2 times greater than for Gaussian-Bessel beams.
基金financially supported by the National Natural Science Foundation of China (No. 21671084)NSF of Jiangsu Province (No. BK20131244)+4 种基金Six talent peaks project in Jiangsu Province (No. 2014-XCL-008)the Qing Lan Project of Jiangsu Province, the Innovation Program of Graduate Students in Jiangsu Province (No. KYLX16-0508)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education InstitutionInnovation Program for Graduate Student from Jiangsu University of Science and Technology (No.YCX15S-19)the Foundation of Jiangsu Educational Committee (No.16KJB430011)
文摘Two novel phase transition materials,[C9H20N2][Na（BF4）3]（1） and[C9H20N2][（PF6）2]（2）,were synthesized based on 1-isopropyl-1,4-diazabicyclo[2.2.2]octan-1-ium with sodium tetrafluoroborate and hexafluorophosphoric acid,respectively.Differential scanning calorimetry measurements detected that 1 and 2 underwent reversible phase transitions,which were confirmed by dielectric measurements.Single crystal X-ray diffraction data suggested that compound 1 changed from a high temperature phase with a space group of P6_3 to a low temperature one with a space group of P21/c,and that compound 2transformed from the space group of Pbca at room temperature to P21/c at low temperature.Formation of hydrogen bonds and distortion of l,4-diazabicyclo[2.2.2]octane rings may drive the transitions.
基金supported by the National Natural Science Foundation of China (50871032)National High Technology Research and Development Program of ChinaProgram of Beijing Municipal Science & Technology
文摘The effect of Sm-rich liquid phase （Sm2Co3） on magnetic properties and microstructure of 2：17-type Sin-Co magnet was studied. Three phases existed in liquid phase ingot, and took on white, dark grey and grey, respectively. It was found that the composition of the grey area was similar to the nominal one. Our results indicated that the optimal composition was obtained at 3 wt.% liquid phase added, and the magnetic properties were B^I 1.58 kGs, Hci〉26 kOe, （BH）m=29.51 MGOe. Br increased by 3%, Hci was 13 times larger, and （B/-/）m was 6 times bigger than none liquid phase magnets. Moreover, with the aging time decreasing from 20 to 8 h, the squareness of the demagnetization curves got better, while the coercivity of the samples decreased. It revealed that Sm（Co,Cu）5 phase also precipitated at particle boundaries. It maybe also enhanced the coercivity.
基金Project(2013AA031601)supported by the National High Technology Research and Development Program of ChinaProject(2012BAF04B01)supported by the National Science and Technology Pillar Program During the 12th Five-year Plan Period of China
文摘Two different kinds of experimental techniques were used to in-situ study the austenite formation during intercritical annealing in C-Mn dual phase steel. The microstructure evolution was observed by confocal laser scanning microscope, and the austenite isothermal and non-isothermal transformation kinetics were studied by dilatometry. The results indicate that banded structure is produced for the reason of composition segregation and the competition between recrystallization and phase transformation. Austenite prefers to nucleate not only at ferrite/ferrite grain boundaries, but also inside the grains of ferrite.Furthermore, the austenitizing process is accomplished mainly via migration of the existing austenite/ferrite interface rather than nucleation of new grains. The incubation process can be divided into two stages which are controlled by carbon and manganese diffusion, respectively. During the incubation process, the nucleation rate of austenite decreases, and austenite growth changes from two-dimensional to one-dimensional. The partitioning coefficient, defined as the ratio of manganese content in the austenite to that in the adjacent ferrite, increases with increasing soaking time.
基金financially supported by the National Natural Science Foundation of China (Grant No. 51571201)
文摘The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy dispersive X-ray spectroscopy (EDX). The galvanic corrosion of the Q-phase/Al couple was found to be dependent on pH and immersion time. Current density maps obtained by SVET shows that the anodic oxidation processes emerge from Al in a localized manner in pH 2 and 6 solutions but is initiated in a uniform manner in pH 13 solution, whereas, the cathodic processes are more homogeneously distributed over the Q-phase at pH 2.6 and 13. It is seen that the Q-phase remains cathodic in the Q-phase/Al couple in acidic, neutral and alkaline solutions indicating that the galvanic polarity of the Q-phase is independent of pH. The effect of the galvanic corrosion was largest at pH 2 and 13 compared to pH 6. The pH map obtained by SIET indicates that the galvanic activity of the Q-phase/Al couple proceeds via heavy alkalization of the Q-phase surface with the generation of appreciable amounts of OH~ ions. The enrichment of Cu indicated by EDX is responsible for the observed cathodic activity of the Q-phase in the Q-phase/Al couple.
文摘A phased array radar seeker（PARS） must be able to effectively decouple body motion and accurately extract the line-of-sight（LOS） rate for target missile tracking.In this study,the realtime two-channel beam pointing error（BPE） compensation method of PARS for LOS rate extraction is designed.The PARS discrete beam motion principium is analyzed,and the mathematical model of beam scanning control is finished.According to the principle of the antenna element shift phase,both the antenna element shift phase law and the causes of beam-pointing error under phantom-bit conditions are analyzed,and the effect of BPE caused by phantom-bit technology（PBT） on the extraction accuracy of the LOS rate is examined.A compensation method is given,which includes coordinate transforms,beam angle margin compensation,and detector dislocation angle calculation.When the method is used,the beam angle margin in the pitch and yaw directions is calculated to reduce the effect of the missile body disturbance and to improve LOS rate extraction precision by compensating for the detector dislocation angle.The simulation results validate the proposed method.
基金provided by the National Natural Science Foundation of China (No. 60777022)the Program for Young Excellent Tal-ents in Tongji University
文摘InAsSb epilayers with a cutoff wavelength of 4.8 μm have been successfully grown on InAs substrates by one-step liquid phase epitaxy （LPE） technology. The epilayers were characterized by X-ray diffraction （XRD）, Fourier transform infrared （PTIR） transmittance measurements and scanning electron microscopy （SEM）. The influence of different growth conditions on the optical and structural properties of the materials was studied. The results revealed that the good crystalline quality, mirror smooth surface and flat interface of InAsSb epilayers were achieved. They benefited from optimized growth conditions, i.e., sufficient homogeneity of the growth melt and a very slow cooling rate.
基金Project supported by the National Natural Science Foundation of China (Grant No 10774145)
文摘Structural phase transitions of Zn4Sb3 and its substitutional compounds （Zn0.98M0.02）4Sb3 （M = Al, Ga and In） are investigated by electrical transport measurement and differential scanning calorimetry below room temperature. The results indicate that both β→α and α→α′ phase transitions of Zn4Sb3 are reversible and exothermic processes, which may be explained as that both the transitions originate from the ordering of the disordered interstitial Zn and vacancies in regular sizes. The derived activation energies of β→α and α→α′ phase transition processes for Zn4Sb3 are E1 = 3.9 eV and E2 = 4.1 eV, respectively. Although no remarkable influence on activation energy E2 is observed after A1 doping, A1 substitution for Zn causes E1 to increase to 4.6 eV, implying its suppression of β←→α transition to a great extent. Moreover, it is found that both β←→α and α←→α′ transitions are completely prohibited by substitution of either In or Ga for Zn in Zn4Sb3. The underlying mechanisms for these phenomena are discussed.
基金supported by the Natural Science Foundation of Henan Province(Grant No.152107000047)
文摘In this study, a two-step heating process is introduced for transient liquid phase ( TLP) diffusion bonding fo r sound joints with T91 heat resistant steels. At first, a short-time higher temperature heating step is addressed to melt the interlayer, followed by the second step to complete isothermal solidification at a low temperature. The most critical feature of our new method is producing a non-planar interface at the T9/ heat resistant steels joint. We propose a transitional liquid phase bonding of T91 heat resistant steels by this approach. Since joint microstructures have been studied, we tested the tensile strength to assess joint mechanical property. The result indicates that the solidified bond may contain a primary solid-solution, similar composition to the parent metal and free from precipitates. Joint tensile strength of the joint is not lower than parent materials. Joint bend's strengths are enhanced due to the higher metal-to-metal junction producing a non-planar bond lines. Nevertheless, the traditional transient liquid phase diffusion bonding produces planar ones. Bonding parameters of new process are 1 260 °C for 0. 5 min and 1 230 °C fo r 4 min.
文摘An investigation was made of the influence of Zr additive on the high temperature phase trans- formations,martensitic forward/reverse transformations,and shape memory effect of Cu-Zn-Al base alloys by means of differential scanning calorimetry(DSC),X-ray diffraction and TEM.It was found that an addition of 0.35 wt-% Zn could effectively inhibit the precipitation of α and γ phases and hence promote the order-martensitic transformations β_2→DO_3→18RM,thus resulting in a minimum activation energy of the martensitic trans- formation and narrow temperature ranges(M_s-M_f)and(A_s-A_f);the alloy so obtained pos- sessed smooth and mobile martensite intervariant interfaces,therefore showing the best shape memory effect.
基金financially supported by the National Natural Science Foundation of China (Nos. 51501143, 51202185 and 51390472)the National Basic Research Program of China (No. 2015CB654903)Fundamental Research Funds for the Central Universities, China Postdoctoral Science Foundation (No. 2015M572554)
文摘Aberration-corrected scanning transmission electron microscopy was employed to investigate the microstructures and secondary phases in LaBaCo2O5.5＋δ（LBCO） thin films grown on SrTiO3 （STO） substrates. The as-grown films showed an epitaxial growth on the substrates with atomically sharp interfaces and orientation relationships of [100]LBCO//[100]STO and （001）LBCO//（001）STO. Secondary phases were observed in the films, which strongly depended on the sample fabrication conditions. In the film prepared at a temperature of 900 ℃, nano-scale CoO pillars nucleated on the substrate, and grew along the [001] direction of the film. In the film grown at a temperature of 1000 ℃, isolated nano-scale C0304 particles appeared, which promoted the growth of {111 } twinning structures in the film. The orientation relationships and the interfaces between the secondary phases and the films were illustrated, and the growth mechanism of the film was discussed.
文摘Differential scanning calorimetry (DSC) measurements of 37 polycrystalline LaH x (2 0<x <3 0) were performed in this work. Samples were synthesized by a direct reaction of a metal with hydrogen at temperatures higher than 250 ℃ (depending on the final composition). DSC measurements were performed in the temperature range of 110～400 K. For the samples in the range of 2 13< x <2 40 single DSC peaks were detected. In the composition range x >2 45 much more complicated DSC signals (double, triple etc. peaks) were observed which some of them were up to 4 phase transformations. Based on these measurements and carried out on high purity samples and supported by high accuracy hydrogen content determination, a new T-x phase diagram for 110< T <400 K and 2< x <3(LaH x ) was proposed. This new phase diagram shows an up to now unknown complexity phase relationships with the existence of at least 11 of phases at T <400 K.
文摘The CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO phase diagram was investigated in the CaO low region (<40 mol.%). CaCl<sub>2</sub>-CaF<sub>2</sub> and CaCl<sub>2</sub>-CaO binary diagrams, constituting the ternary system, were first studied by Differential Scanning Calorimetry (DSC) measurements and X-Ray Diffraction (XRD) characterization;a good agreement was obtained between the phase diagram models calculated with FactSage®software (FTsalt database) and present experimental data. As the CaF<sub>2</sub>-CaO liquidus could not be measured by DSC due to the high melting temperature, this diagram was calculated using FTsalt database combined with FToxid database of FactSage<sup>®</sup> software. The ternary phase diagram was obtained by calculations and exhibits an eutectic at the composition CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO (78.2-15.7-6.1 mol.%) melting at 637°C, and five peritectic points. Measurements of relevant vertical cross-sections for three CaCl<sub>2</sub>-CaF<sub>2</sub> compositions (50-50, 40-60 and 30-70 mol.%) up to 18 mol.% CaO are in agreement with the ternary phase diagram model. For each section, the liquidus temperature is constant up to around 11 mol.% CaO and then sharply increases. Moreover, an increase of CaF<sub>2</sub> content in CaCl<sub>2</sub>-CaF<sub>2</sub> melt leads to a decrease of the CaO solubility in isothermal condition.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.51575134 and 51205083)
文摘A feature extraction method was proposed to sectorial scan image of Ti-6Al-4V electron beam welding seam based on principal component analysis to solve problem of high-dimensional data resulting in timeconsuming in defect recognition. Seven features were extracted from the image and represented 87. 3% information of the original data. Both the extracted features and the original data were used to train support vector machine model to assess the feature extraction performance in two aspects: recognition accuracy and training time. The results show that using the extracted features the recognition accuracy of pore,crack,lack of fusion and lack of penetration are 93%,90.7%,94.7% and 89.3%,respectively,which is slightly higher than those using the original data. The training time of the models using the extracted features is extremely reduced comparing with those using the original data.
