Raman spectra of undoped GaN and Mg-doped GaN films grown by metal-organic chemical-vapor deposition on sapphire are investigated between 78 and 573K.A peak at 247cm -1 is observed in both Raman spectra of GaN and Mg-...Raman spectra of undoped GaN and Mg-doped GaN films grown by metal-organic chemical-vapor deposition on sapphire are investigated between 78 and 573K.A peak at 247cm -1 is observed in both Raman spectra of GaN and Mg-doped GaN.It is suggested that the defect-induced scattering is origin of the mode.The electronic Raman scattering mechanism and Mg-related local vibrational mode are excluded.Furthermore,the differences of E_2 and A_1(LO) modes in two samples are also discussed.The stress relaxation is observed in Mg-doped GaN.展开更多
This paper stuides numerically the model equation in a one dimensional defective photonic lattice by modifying the potential function to a periodic function. It is found that defect modes （DMs） can be regarded as Bl...This paper stuides numerically the model equation in a one dimensional defective photonic lattice by modifying the potential function to a periodic function. It is found that defect modes （DMs） can be regarded as Bloch modes which are excited from the extended photonie band-gap structure at Bloch wave-numbers with kx = 0. The DMs for both positive and negative defects are considered in this method.展开更多
Employing the characteristic matrix method, this study investigates transmission properties of onedimensional defective lossy photonic crystals composed of negative and positive refractive index layers with one lossle...Employing the characteristic matrix method, this study investigates transmission properties of onedimensional defective lossy photonic crystals composed of negative and positive refractive index layers with one lossless defect layer at the center of the crystal. The results of the study show that as the refractive index and thickness of the defect layer increase, the frequency of the defect mode decreases. In addition, the study shows that the frequency of the defect mode is sensitive to the incidence angle, polarization, and physical properties of the defect layer, but it is insensitive to the small lattice loss factor. The peak of the defect mode is very sensitive to the loss factor, incidence angle, polarization, refractive index, and thickness of the defect layer. This study also shows that the peak and the width of the defect mode are affected by the numbers of the lattice period and the loss factor. The results can lead to designing new types of narrow filter structures and other optical devices.展开更多
By means of a transfer matrix method, this paper deduces the transmittance calculation equation of light travelling in locally doped （including one defect layer） mirror heterostructure （ABCCBA）PD（ABCCBA）q photon...By means of a transfer matrix method, this paper deduces the transmittance calculation equation of light travelling in locally doped （including one defect layer） mirror heterostructure （ABCCBA）PD（ABCCBA）q photonic crystals. In the cases of defect layers being either introduced or not introduced, an ORIGIN simulation shows the influence of incident angle change on the number of photon band gap, bandwidth and defect mode numbers. Studies indicate that when such photonic crystals have 8 mirror cycles and the thickness of defect layer D meets nDdD = X0/2 or nodD = 4）~0, the photonic crystal defect mode transmission peak changes significantly. Also, with the change of incident angle, the number of defect mode transmission peaks changes. By altering incident angle and defect layer thickness, we can get photon band gaps and defect mode transmission peaks at different frequency domains and different relative angular frequencies. This provides theoretical reference for achieving light wave multi-channel filtering and tunable filtering.展开更多
Wave propagation is studied in structures consisting of alternate left- and right-handed layers. Bragg gap and zero-n gap appear in different frequency regions of the structure. The periodicity of the structure is bro...Wave propagation is studied in structures consisting of alternate left- and right-handed layers. Bragg gap and zero-n gap appear in different frequency regions of the structure. The periodicity of the structure is broken by simply reversing the order of the layers in one half of the structure, resulting in defect modes located inside the zero-n gap and Bragg gap. These modes can be made very narrow by adding more layers in the structure. The defect mode located inside the zero-n gap is sensitive to the symmetry of the structure and insensitive to the angle of incidence of the incoming radiation. Multiple modes are also generated inside the gaps by repeating the structural pattern. Thus, a simple structure can be used for single and multiple modes that are imDortant for different applications.展开更多
The multi-modes and disperse characteristics of torsional modes in pipes are investigated theoretically and experimentally. At all frequencies, both phase velocity and group velocity of the lowest torsional mode T（0,...The multi-modes and disperse characteristics of torsional modes in pipes are investigated theoretically and experimentally. At all frequencies, both phase velocity and group velocity of the lowest torsional mode T（0,1） are constant and equal to shear wave velocity. T（0,1） mode at all frequencies is the fastest torsional mode. In the experiments, T（0,1） mode is excited and received in pipes using 9 thickness shear vibration mode piezoelectric ceramic elements. Furthermore, an artificial longitudinal defect of a 4 m long pipe is detected using T（0,1） mode at 50 kHz. Experimental results show that it is feasible for longitudinal defect detection in pipes using T（0,1） mode of ultrasonic guided waves.展开更多
The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three different types of welding cracks in welded joints were investigated by optical microscopy,scanning electron m...The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three different types of welding cracks in welded joints were investigated by optical microscopy,scanning electron microscopy and electron back-scattered diffraction.Finally,the failure mode of the welded joints in shear tensile test was discussed.It is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering current.The surface crack in welded joint is intergranular fracture,while the inner crack in welded joint is transgranular fracture,and the surface crack on the edge of the electrode imprint can be improved by adding preheating current or tempering current.The traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.展开更多
Objective To explore the ＂3＋1＂ monitoring mode for birth defects and quality control measures based on the population, and to obtain the related information data for birth defects.Methods With the community populat...Objective To explore the ＂3＋1＂ monitoring mode for birth defects and quality control measures based on the population, and to obtain the related information data for birth defects.Methods With the community population as the basis, adopting the unified monitoring scheme dominant by the leadership and administration of government, with districts （counties） as the monitoring sites, the ＂3＋1 ＂ monitoring mode for birth defects was based on a complete monitoring team with the combination of villages/residents＇ committees, townships （towns）, counties （districts） and the municipality. Demonstration research was carried out in the pilot districts/counties in Chongqing City.Results Birth defects population monitoring system based on population and family planning management and service network was established, and during 2005 and 2006.application research was carried out for the monitoring methods among birth defects population in the pilot districts （counties）, obtaining the relevant information in regional birth defects, with a monitoring coverage of over 99%. Conclusion Fully utilizing the birth management functions of Population and Famlty Planning System and the advantages of service networks, long term, dynamic birth defects monitoring system based on community population was established, with the integration of birth defects monitoring and regular reproductive health services, obtaining overall birth defects occurrence information in details, providing scientific basis for the government to formulate scientific, practical, economic and effective birth defects intervention policy, so as to improve the quality of the population.展开更多
A one dimensional model is developed for defective gap mode（DGM）with two types of boundary conditions：conducting mesh and conducting sleeve.For a periodically modulated system without defect,the normalized width of...A one dimensional model is developed for defective gap mode（DGM）with two types of boundary conditions：conducting mesh and conducting sleeve.For a periodically modulated system without defect,the normalized width of spectral gaps equals to the modulation factor,which is consistent with previous studies.For a periodic system with local defects introduced by the boundary conditions,it shows that the conducting-mesh-induced DGM is always well confined by spectral gaps while the conducting-sleeve-induced DGM is not.The defect location can be a useful tool to dynamically control the frequency and spatial periodicity of DGM inside spectral gaps.This controllability can be potentially applied to the interaction between gap eigenmodes and energetic particles in fusion plasmas,and optical microcavities and waveguides in photonic crystals.展开更多
The metamaterial constructed by Helmholtz resonators (HR) has low-frequency acoustic forbidden bands and possesses negative mass density and effective bulk modulus at particular frequencies. The resonant modes in one-...The metamaterial constructed by Helmholtz resonators (HR) has low-frequency acoustic forbidden bands and possesses negative mass density and effective bulk modulus at particular frequencies. The resonant modes in one-dimensional HR structure with point defect were studied using finite element method (FEM). The results show that the acoustic energy is localized between the resonant HR and the opening in the local-resonant-type gap. There is a high pressure area around the defect resonator at the frequency of defect mode. In the Bragg type gap, the energy mainly distributes in the waveguide with harmonic attenuation due to the multi-scattering. Phase opposition demonstrates the existence of negative dynamic mass density. Local negative parameter is observed in the pass band due to the defect mode. Based on further investigation of the acoustic intensity and phase distributions in the resonators corresponding to two different forbidden bands, only one local resonant mode is verified, which is different from the three-component local resonant phononics. This work will be useful for understanding the mechanisms of acoustic forbidden bands and negative parameters in the HR metamaterial, and of help for designing new functional acoustic devices.展开更多
Based on finite-difference time-domain(FDTD) method,the wave propagation and localization in two-dimensional defect-containing piezoelectric phononic crystals are investigated when the mechanical-electrical coupling i...Based on finite-difference time-domain(FDTD) method,the wave propagation and localization in two-dimensional defect-containing piezoelectric phononic crystals are investigated when the mechanical-electrical coupling is taken into account.The characteristics of localized defect modes are studied,and the effects of the number and direction of defects on the defect modes and transmission coefficients are discussed.Numerical results of defect modes and transmission coefficients are presented for BaTiO3/polymer piezocomposite,and from which we can see that the number and direction of defects have pronounced effects on the defect modes and transmission coefficients.The results also show the existence of elastic wave localization in piezoelectric phononic crystals containing defects.展开更多
Infrared absorption local vibration mode（LVM） spectroscopy is used to study hydrogen related defects in n-type ZnO single crystal grown by a closed chemical vapor transport（CVT） method under Zn-rich growth conditi...Infrared absorption local vibration mode（LVM） spectroscopy is used to study hydrogen related defects in n-type ZnO single crystal grown by a closed chemical vapor transport（CVT） method under Zn-rich growth conditions, in which carbon is used as a transport agent. Two C-H complex related absorption peaks at 2850 cm-1and 2919 cm-1 are detected in the sample. The formation of the C-H complex implies an effect of carbon donor passivation and formation suppression of H donor in ZnO. The influence of the complex defects on the electrical property of the CVT-ZnO is discussed based on Hall measurement results and residual impurity analysis.展开更多
This paper addresses the studies carried out on an I-beam to reveal the wave propagation characteristics and tackle the multi-mode propagation of Lamb waves. The experimental setup consisted of a new 3D Scanning Laser...This paper addresses the studies carried out on an I-beam to reveal the wave propagation characteristics and tackle the multi-mode propagation of Lamb waves. The experimental setup consisted of a new 3D Scanning Laser Doppler Vibrometer manufactured by Polytec (3D-SLDV) and was used to acquire high resolution time-space Lamb waves that were propagating in the I-beam. A high power and pulsed Nd:YAG laser was used to emit the required Lamb waves. The emission and sensing of the waves were carried out simultaneously. The wave propagation data was recorded by scanning the surface of the I-beam in a sequential manner. The measured data was used to construct the wave patterns that were propagating in the I-beams at different time instants. Furthermore, as the waves in an I-Beam propagate with multiple modes even at low frequency range, filtering was carried out in the frequency-wavenum- ber domain in order to decompose the modes. The results presented thereby confirm that the new 3D-SLDV possesses tremendous capability in revealing the wave propagation characteristics and its interaction with defect. The results could be the first time that the waves propagating in a real I-beam can be visually observed, whilst in the past, it can only be visualized through simulation. The capability of using such totally laser-based 3D inspection system to reveal the characteristics of Lamb wave and its interaction with defects are substantial.展开更多
According to the operation characteristics of autoclave, the possible defects are analyzed by damage modes, the inspection methods are selected contrapuntally, and the causes of the defects affecting the safe operatio...According to the operation characteristics of autoclave, the possible defects are analyzed by damage modes, the inspection methods are selected contrapuntally, and the causes of the defects affecting the safe operation of the equipment are analyzed. This study effectively improves the quality of inspection work and plays an important role in strengthening the management of equipment use and reducing accidents.展开更多
岩石受压激发电流(pressure-stimulated rock current,PSRC)变化是岩体破裂观测与地壳灾变感知研究的重要内容,但缺乏岩石含水状态与加载模式对PSRC变化特征的影响探究与机理辨析.本文以粒度相对均匀的闪长岩为实验对象,特别制备了方柱...岩石受压激发电流(pressure-stimulated rock current,PSRC)变化是岩体破裂观测与地壳灾变感知研究的重要内容,但缺乏岩石含水状态与加载模式对PSRC变化特征的影响探究与机理辨析.本文以粒度相对均匀的闪长岩为实验对象,特别制备了方柱-锥体闪长岩试件,采用高精度静电计与声发射探测仪,同步观测单、双轴局部加载破裂过程中充分干燥、自然干燥和充分饱水试件的受压端与非受压端之间PSRC及声发射变化,并分析其特征差异,辨析其内在机理.研究揭示:(1)全部试件受力中后期均呈现PSRC显著增长,包括毛刺型、持续增大型和瞬时台阶型,其增幅受含水状态和加载模式综合影响;(2)岩石临失稳前,PSRC均呈现剧烈脉冲式振荡特征,其中单、双轴模式下充分饱水试件的峰值PSRC分别是充分干燥试件的1.3倍和7.1倍,而自然干燥试件的峰值PSRC受加载模式影响不大;(3)自然干燥试件中的微量孔隙水对正空穴电荷传递有损耗作用,而充分饱水试件的流体电动势效应对PSRC变化影响显著,闪长岩所含石英矿物对PSRC的贡献可以忽略.本文揭示的岩石临失稳前PSRC剧变现象、峰值差异及内在机理,对于发展岩体灾变监测预警新技术和构造地震孕震区遥感识别新方法有重要意义.展开更多
文摘Raman spectra of undoped GaN and Mg-doped GaN films grown by metal-organic chemical-vapor deposition on sapphire are investigated between 78 and 573K.A peak at 247cm -1 is observed in both Raman spectra of GaN and Mg-doped GaN.It is suggested that the defect-induced scattering is origin of the mode.The electronic Raman scattering mechanism and Mg-related local vibrational mode are excluded.Furthermore,the differences of E_2 and A_1(LO) modes in two samples are also discussed.The stress relaxation is observed in Mg-doped GaN.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10674038 and 10604042)the National Basic Research Program of China (Grant No. 2006CB302901)
文摘This paper stuides numerically the model equation in a one dimensional defective photonic lattice by modifying the potential function to a periodic function. It is found that defect modes （DMs） can be regarded as Bloch modes which are excited from the extended photonie band-gap structure at Bloch wave-numbers with kx = 0. The DMs for both positive and negative defects are considered in this method.
文摘Employing the characteristic matrix method, this study investigates transmission properties of onedimensional defective lossy photonic crystals composed of negative and positive refractive index layers with one lossless defect layer at the center of the crystal. The results of the study show that as the refractive index and thickness of the defect layer increase, the frequency of the defect mode decreases. In addition, the study shows that the frequency of the defect mode is sensitive to the incidence angle, polarization, and physical properties of the defect layer, but it is insensitive to the small lattice loss factor. The peak of the defect mode is very sensitive to the loss factor, incidence angle, polarization, refractive index, and thickness of the defect layer. This study also shows that the peak and the width of the defect mode are affected by the numbers of the lattice period and the loss factor. The results can lead to designing new types of narrow filter structures and other optical devices.
基金supported by the National Natural Science Foundation of China(Nos.60776062,50730009)
文摘By means of a transfer matrix method, this paper deduces the transmittance calculation equation of light travelling in locally doped （including one defect layer） mirror heterostructure （ABCCBA）PD（ABCCBA）q photonic crystals. In the cases of defect layers being either introduced or not introduced, an ORIGIN simulation shows the influence of incident angle change on the number of photon band gap, bandwidth and defect mode numbers. Studies indicate that when such photonic crystals have 8 mirror cycles and the thickness of defect layer D meets nDdD = X0/2 or nodD = 4）~0, the photonic crystal defect mode transmission peak changes significantly. Also, with the change of incident angle, the number of defect mode transmission peaks changes. By altering incident angle and defect layer thickness, we can get photon band gaps and defect mode transmission peaks at different frequency domains and different relative angular frequencies. This provides theoretical reference for achieving light wave multi-channel filtering and tunable filtering.
文摘Wave propagation is studied in structures consisting of alternate left- and right-handed layers. Bragg gap and zero-n gap appear in different frequency regions of the structure. The periodicity of the structure is broken by simply reversing the order of the layers in one half of the structure, resulting in defect modes located inside the zero-n gap and Bragg gap. These modes can be made very narrow by adding more layers in the structure. The defect mode located inside the zero-n gap is sensitive to the symmetry of the structure and insensitive to the angle of incidence of the incoming radiation. Multiple modes are also generated inside the gaps by repeating the structural pattern. Thus, a simple structure can be used for single and multiple modes that are imDortant for different applications.
基金This project is supported by National Natural Science Foundation of China(No. 10272007, No.60404017, No.10372009)Municipal Natural Science Foundation of Beijing, Clina(No.4052008).
文摘The multi-modes and disperse characteristics of torsional modes in pipes are investigated theoretically and experimentally. At all frequencies, both phase velocity and group velocity of the lowest torsional mode T（0,1） are constant and equal to shear wave velocity. T（0,1） mode at all frequencies is the fastest torsional mode. In the experiments, T（0,1） mode is excited and received in pipes using 9 thickness shear vibration mode piezoelectric ceramic elements. Furthermore, an artificial longitudinal defect of a 4 m long pipe is detected using T（0,1） mode at 50 kHz. Experimental results show that it is feasible for longitudinal defect detection in pipes using T（0,1） mode of ultrasonic guided waves.
文摘The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three different types of welding cracks in welded joints were investigated by optical microscopy,scanning electron microscopy and electron back-scattered diffraction.Finally,the failure mode of the welded joints in shear tensile test was discussed.It is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering current.The surface crack in welded joint is intergranular fracture,while the inner crack in welded joint is transgranular fracture,and the surface crack on the edge of the electrode imprint can be improved by adding preheating current or tempering current.The traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.
基金The research has been C1 Project of the Three Major Programs in the Family Planning/High Quality Reproductive Health Services by the National Population and Family Planning Commission(2005C1-46)one of the key projects funded for social development by the Science & Technology Commission of Chongqing Municipality (8306-CSTC, 2004AC5018)
文摘Objective To explore the ＂3＋1＂ monitoring mode for birth defects and quality control measures based on the population, and to obtain the related information data for birth defects.Methods With the community population as the basis, adopting the unified monitoring scheme dominant by the leadership and administration of government, with districts （counties） as the monitoring sites, the ＂3＋1 ＂ monitoring mode for birth defects was based on a complete monitoring team with the combination of villages/residents＇ committees, townships （towns）, counties （districts） and the municipality. Demonstration research was carried out in the pilot districts/counties in Chongqing City.Results Birth defects population monitoring system based on population and family planning management and service network was established, and during 2005 and 2006.application research was carried out for the monitoring methods among birth defects population in the pilot districts （counties）, obtaining the relevant information in regional birth defects, with a monitoring coverage of over 99%. Conclusion Fully utilizing the birth management functions of Population and Famlty Planning System and the advantages of service networks, long term, dynamic birth defects monitoring system based on community population was established, with the integration of birth defects monitoring and regular reproductive health services, obtaining overall birth defects occurrence information in details, providing scientific basis for the government to formulate scientific, practical, economic and effective birth defects intervention policy, so as to improve the quality of the population.
基金supported by National Natural Science Foundation of China(No.11405271)
文摘A one dimensional model is developed for defective gap mode（DGM）with two types of boundary conditions：conducting mesh and conducting sleeve.For a periodically modulated system without defect,the normalized width of spectral gaps equals to the modulation factor,which is consistent with previous studies.For a periodic system with local defects introduced by the boundary conditions,it shows that the conducting-mesh-induced DGM is always well confined by spectral gaps while the conducting-sleeve-induced DGM is not.The defect location can be a useful tool to dynamically control the frequency and spatial periodicity of DGM inside spectral gaps.This controllability can be potentially applied to the interaction between gap eigenmodes and energetic particles in fusion plasmas,and optical microcavities and waveguides in photonic crystals.
文摘The metamaterial constructed by Helmholtz resonators (HR) has low-frequency acoustic forbidden bands and possesses negative mass density and effective bulk modulus at particular frequencies. The resonant modes in one-dimensional HR structure with point defect were studied using finite element method (FEM). The results show that the acoustic energy is localized between the resonant HR and the opening in the local-resonant-type gap. There is a high pressure area around the defect resonator at the frequency of defect mode. In the Bragg type gap, the energy mainly distributes in the waveguide with harmonic attenuation due to the multi-scattering. Phase opposition demonstrates the existence of negative dynamic mass density. Local negative parameter is observed in the pass band due to the defect mode. Based on further investigation of the acoustic intensity and phase distributions in the resonators corresponding to two different forbidden bands, only one local resonant mode is verified, which is different from the three-component local resonant phononics. This work will be useful for understanding the mechanisms of acoustic forbidden bands and negative parameters in the HR metamaterial, and of help for designing new functional acoustic devices.
基金Sponsored by the National Natural Science Foundation of China(Grant No.10672017 and 10632020)the China Postdoctoral Science Foundation+1 种基金Heilongjiang Province Postdoctoral Science FoundationJapan Society for the Promotion of Science(JSPS)
文摘Based on finite-difference time-domain(FDTD) method,the wave propagation and localization in two-dimensional defect-containing piezoelectric phononic crystals are investigated when the mechanical-electrical coupling is taken into account.The characteristics of localized defect modes are studied,and the effects of the number and direction of defects on the defect modes and transmission coefficients are discussed.Numerical results of defect modes and transmission coefficients are presented for BaTiO3/polymer piezocomposite,and from which we can see that the number and direction of defects have pronounced effects on the defect modes and transmission coefficients.The results also show the existence of elastic wave localization in piezoelectric phononic crystals containing defects.
基金Project supported by the National Natural Science Foundation of China(Grant No.61474104)
文摘Infrared absorption local vibration mode（LVM） spectroscopy is used to study hydrogen related defects in n-type ZnO single crystal grown by a closed chemical vapor transport（CVT） method under Zn-rich growth conditions, in which carbon is used as a transport agent. Two C-H complex related absorption peaks at 2850 cm-1and 2919 cm-1 are detected in the sample. The formation of the C-H complex implies an effect of carbon donor passivation and formation suppression of H donor in ZnO. The influence of the complex defects on the electrical property of the CVT-ZnO is discussed based on Hall measurement results and residual impurity analysis.
文摘This paper addresses the studies carried out on an I-beam to reveal the wave propagation characteristics and tackle the multi-mode propagation of Lamb waves. The experimental setup consisted of a new 3D Scanning Laser Doppler Vibrometer manufactured by Polytec (3D-SLDV) and was used to acquire high resolution time-space Lamb waves that were propagating in the I-beam. A high power and pulsed Nd:YAG laser was used to emit the required Lamb waves. The emission and sensing of the waves were carried out simultaneously. The wave propagation data was recorded by scanning the surface of the I-beam in a sequential manner. The measured data was used to construct the wave patterns that were propagating in the I-beams at different time instants. Furthermore, as the waves in an I-Beam propagate with multiple modes even at low frequency range, filtering was carried out in the frequency-wavenum- ber domain in order to decompose the modes. The results presented thereby confirm that the new 3D-SLDV possesses tremendous capability in revealing the wave propagation characteristics and its interaction with defect. The results could be the first time that the waves propagating in a real I-beam can be visually observed, whilst in the past, it can only be visualized through simulation. The capability of using such totally laser-based 3D inspection system to reveal the characteristics of Lamb wave and its interaction with defects are substantial.
文摘According to the operation characteristics of autoclave, the possible defects are analyzed by damage modes, the inspection methods are selected contrapuntally, and the causes of the defects affecting the safe operation of the equipment are analyzed. This study effectively improves the quality of inspection work and plays an important role in strengthening the management of equipment use and reducing accidents.
文摘岩石受压激发电流(pressure-stimulated rock current,PSRC)变化是岩体破裂观测与地壳灾变感知研究的重要内容,但缺乏岩石含水状态与加载模式对PSRC变化特征的影响探究与机理辨析.本文以粒度相对均匀的闪长岩为实验对象,特别制备了方柱-锥体闪长岩试件,采用高精度静电计与声发射探测仪,同步观测单、双轴局部加载破裂过程中充分干燥、自然干燥和充分饱水试件的受压端与非受压端之间PSRC及声发射变化,并分析其特征差异,辨析其内在机理.研究揭示:(1)全部试件受力中后期均呈现PSRC显著增长,包括毛刺型、持续增大型和瞬时台阶型,其增幅受含水状态和加载模式综合影响;(2)岩石临失稳前,PSRC均呈现剧烈脉冲式振荡特征,其中单、双轴模式下充分饱水试件的峰值PSRC分别是充分干燥试件的1.3倍和7.1倍,而自然干燥试件的峰值PSRC受加载模式影响不大;(3)自然干燥试件中的微量孔隙水对正空穴电荷传递有损耗作用,而充分饱水试件的流体电动势效应对PSRC变化影响显著,闪长岩所含石英矿物对PSRC的贡献可以忽略.本文揭示的岩石临失稳前PSRC剧变现象、峰值差异及内在机理,对于发展岩体灾变监测预警新技术和构造地震孕震区遥感识别新方法有重要意义.
