The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E ...The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance.展开更多
We developed a parallelized scheme of 3D finite difference (3DFD)with non-oniform staggered grid to simulate the eccentric borehole acoustic field with side-wall acoustic logging tools in open and cased wells. Highe...We developed a parallelized scheme of 3D finite difference (3DFD)with non-oniform staggered grid to simulate the eccentric borehole acoustic field with side-wall acoustic logging tools in open and cased wells. Higher accuracy and lower computation cost were achieved with this scheme for modeling such an asymmetric wave field generated by a high frequency source near or on the borehole wall. We also modeled the cases with and without considering the effects of the tool body. The simulation results demonstrated that the logging tool body would attenuate the direct waves but have only little influence on the interface waves in such a borehole condition. The effects of the tool body on the wave field were significant only when the contrast of the elastic properties between tool body and borehole fluid was large.展开更多
In this paper, uniaxial compression tests were carried out on a series of composite rock specimens with different dip angles, which were made from two types of rock-like material with different strength. The acoustic ...In this paper, uniaxial compression tests were carried out on a series of composite rock specimens with different dip angles, which were made from two types of rock-like material with different strength. The acoustic emission technique was used to monitor the acoustic signal characteristics of composite rock specimens during the entire loading process. At the same time, an optical non-contact 3 D digital image correlation technique was used to study the evolution of axial strain field and the maximal strain field before and after the peak strength at different stress levels during the loading process. The effect of bedding plane inclination on the deformation and strength during uniaxial loading was analyzed. The methods of solving the elastic constants of hard and weak rock were described. The damage evolution process, deformation and failure mechanism, and failure mode during uniaxial loading were fully determined. The experimental results show that the θ = 0?–45?specimens had obvious plastic deformation during loading, and the brittleness of the θ = 60?–90?specimens gradually increased during the loading process. When the anisotropic angle θincreased from 0?to 90?, the peak strength, peak strain,and apparent elastic modulus all decreased initially and then increased. The failure mode of the composite rock specimen during uniaxial loading can be divided into three categories:tensile fracture across the discontinuities(θ = 0?–30?), slid-ing failure along the discontinuities(θ = 45?–75?), and tensile-split along the discontinuities(θ = 90?). The axial strain of the weak and hard rock layers in the composite rock specimen during the loading process was significantly different from that of the θ = 0?–45?specimens and was almost the same as that of the θ = 60?–90?specimens. As for the strain localization highlighted in the maximum principal strain field, the θ = 0?–30?specimens appeared in the rock matrix approximately parallel to the loading direction,while in the θ = 45?–90?specimens it appeared at the hard and weak rock layer interface.展开更多
The 3-D seismic dataset is a key tool to analyze and understand the mechanism of structural and stratigraphic hydrocarbon(HC)trapping in the subsurface.Conventionally used subsurface seismic characterization methods f...The 3-D seismic dataset is a key tool to analyze and understand the mechanism of structural and stratigraphic hydrocarbon(HC)trapping in the subsurface.Conventionally used subsurface seismic characterization methods for fractures are based on the theory of effective anisotropy medium.The aim of this work is to improve the structural images with dense sampling of 3-D survey to evaluate structural and stratigraphic models for reservoir development to predict reservoir quality.The present study of the Gullfaks Field,located in the Norwegian North Sea Gullfaks sector,identifies the shallowest structural elements.The steepness of westward structural dip decreases eastward during the Upper Jurassic to Lower Cretaceous deposition.Reservoir sands consist of the Middle Jurassic deltaic deposits and Lower Jurassic fluvial channel and delta plain deposits.Sediment supply steadily prevails on sea-level rise and the succession displays a regressive trend indicated by a good continuous stacking pattern.The key factor for the development of reservoirs in the Gullfaks Field is fault transmissibility with spatially distributed pressure.The majority of mapped faults with sand-to-sand contacts are non-sealing,which provide restriction for the HC flow between the fault blocks.The traps for HC accumulation occur between the post-rift and syn-rift strata,i.e.antiform set by extensional system,unconformity trap at the top of syndeposition,and structural trap due to normal faults.Overall reservoir quality in the studied area is generally excellent with average 35%porosity and permeability in the Darcy range.Our findings are useful to better understand the development of siliciclastic reservoirs in similar geological settings worldwide.展开更多
The creation and propagation of longitudinal acoustic phonons (LAPs) in high quality hematite thin films (α-Fe203) epitaxially grown on different substrates (BaTiO3, SrTiO3, and LaAlO3) are investigated using t...The creation and propagation of longitudinal acoustic phonons (LAPs) in high quality hematite thin films (α-Fe203) epitaxially grown on different substrates (BaTiO3, SrTiO3, and LaAlO3) are investigated using the femtosecond pump- probe technique. Transient reflection measurements (AR/R) indicate the photo-excited electron dynamics, and the initial decay less than 1 ps and the slow decay of -500 ps are attributed to the electron-LO phonon coupling and electron-hole nonradiative recombination, respectively. LAPs in α-Fe2O3 film can be created by ultrafast excitation of the ligand field state, such as the ligand field transitions under 800-nm excitation as well as the ligand to metal charge-transfer with 400- nm excitation. The strain modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.展开更多
After the field equations and the snonumuoo conditions between the interfaces for 3D eddy current problems Under various gauges were discussed, it was pointed cut in this paper that using the magnetic vector potentia...After the field equations and the snonumuoo conditions between the interfaces for 3D eddy current problems Under various gauges were discussed, it was pointed cut in this paper that using the magnetic vector potential A. the electric scalar potential and Coulomb gauge △ .A = 0 in eddy current regions and using the magntetic scalar potential Ω in the non-conducting regions are more suitable. All field equations, the boundary conditions, the interface continuity conditions and the corresponding variational principle of this method are also given展开更多
为了提高混响室声场模拟能力,北京卫星环境工程研究所自研一套高声强声场模拟试验设备。文章介绍了该设备的行波管发声系统设计和消声降噪处理过程——行波终端设计以及声试验控制仪器的原理。经过调试试验验证,测量结果满足声压级165 ...为了提高混响室声场模拟能力,北京卫星环境工程研究所自研一套高声强声场模拟试验设备。文章介绍了该设备的行波管发声系统设计和消声降噪处理过程——行波终端设计以及声试验控制仪器的原理。经过调试试验验证,测量结果满足声压级165 d B行波声场的要求,行波管试验段性能良好,达到167.9 d B,消声道出口噪声能够满足环境模拟需求。展开更多
The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China. The deformation evolu...The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China. The deformation evolution, the structure of strain and stress fields and its ore-controlling effect in the Shangzhuang deposit are discussed in this paper. It is revealed that the deformation evolution has mainly undergone four phases: the early ductile deformation, the second NE-striking horizontal simple shear, the third NE-striking compression-shear and the final NW-striking compression. The mineralization happened during the third stage in which the maximum principal stress gradually transited from NE to NW. The 3-D numerical simulations of the stress field show that, on the condition that the maximum principal stress is NE-striking, the fracture development in the fault zone is favored, while when the maximum principal stress is NW-striking, the fault zone is relatively extensional and it is suitable for the influx and emplacement of ore-forming fluids. The compression-shear strain field during the mineralization is characterized by the λ-type structure, the positive flower structure, etc. Orebodies are mostly equidistantly located in the dilatational spaces, which are distributed in the integral compressional circumstances. And the dilatational spaces are developed where the fault attitude changes or shear joint systems develop. In the overall compression-shear stress field, the strain field bears self-similarity at multiple scales, including the orebody, ore deposit and orefield. The selfsimilarity of the structure comprises the subequidistant distribution of fractures at the same scale and the similar shape of the fractures at various scales. Yet, due to the special geological structure, the orebodies are mostly located in the hanging wall in the Shangzhuang deposit, which is different from most deposits in the Jiaodong gold province. Analyses of the ore-controlling stress and strain fields in the deposit provide an important basis for deposit seeking.展开更多
The borehole acoustic reflection imaging logging is a newly developed acoustic logging method that has attracted many interests. These converted and reflected waves for imaging are usually mixed up with borehole guide...The borehole acoustic reflection imaging logging is a newly developed acoustic logging method that has attracted many interests. These converted and reflected waves for imaging are usually mixed up with borehole guided waves and therefore difficult to be clearly identified. To improve the downhole tool design and develop more sophisticate data processing and interpretation algorithms,studies on precisely numerical modeling of the wave fields in the acoustic reflection imaging logging are neces-sary and critical. This paper developed a parallelized scheme of 3D finite difference (3DFD) with non-uniform staggered grid and PML absorbing boundary to simulate the acoustic wave fields in isotropic and anisotropic formations. Applications of this scheme to the typical cases of isotropic and anisot-ropic formations and comparison with the results from published analytical solutions have demon-strated the validation and efficiency of the scheme. Higher accuracy and lower computation cost (3.5 times faster than the conventional schemes) have been achieved with this scheme for modeling such a complex wave fields of 60 dB dynamic range with higher frequency (10 kHz). This simulating program provides a quantitative analytical means for studying acoustic reflection imaging tool and development of the data processing and interpretation methods.展开更多
In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor(CR-PMSM),the effectiveness of two methods was studied on handling of problems concerned with non-uniform distributi...In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor(CR-PMSM),the effectiveness of two methods was studied on handling of problems concerned with non-uniform distribution of magnetic field along axial direction in CR-PMSM,which were sectional calculation(SC)method and three-dimensional finite element(3-D FE)method.On this basis,the influence of the axial displacement and dq-axis currents on the operating characteristics of axial magnetic force and torque is analyzed by using the 3-D FE model.Analysis results show that the axial magnetic force and torque decrease with the increase of axial displacement of the rotor,and the amplitude regularity of the axial magnetic force is affected by the d-axis current.A prototype machine is fabricated and tested,in order to validate the design theory.展开更多
Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part ...Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part has been given. The influences of source field period, the conductivity, the buried depth and the length of the conductor on the transfer functions were studied. The extrema of transfer functions appear at the center, the four corners and around the edges of conductor, and move with the edges. This feature demonstrates that around the edges are best places for transfer functions' observation.展开更多
The InjectorⅡ, one of the two parallel injectors of the high-current superconducting proton driver linac for the China Accelerator-Driven System (C-ADS) project, is being designed and constructed by the Institute o...The InjectorⅡ, one of the two parallel injectors of the high-current superconducting proton driver linac for the China Accelerator-Driven System (C-ADS) project, is being designed and constructed by the Institute of Modern Physics. At present, the design work for the injector is almost finished. End-to-end simulation has been carried out using the TRACK multiparticle simulation code to check the match between each acceleration section and the performance of the injector as a whole. Moreover, multiparticle simulations with all kinds of errors and misalignments have been performed to define the requirements of each device. The simulation results indicate that the lattice design is robust. In this paper, the results of end-to-end simulation and error simulation with a 3-D field map are presented.展开更多
The recognition of 3-D objects is quite a difficult task for computer vision systems.This paper presents a new object framework,which utilizes densely sampled grids with different resolutions to represent the local in...The recognition of 3-D objects is quite a difficult task for computer vision systems.This paper presents a new object framework,which utilizes densely sampled grids with different resolutions to represent the local information of the input image.A Markov random field model is then created to model the geometric distribution of the object key nodes.Flexible matching,which aims to find the accurate correspondence map between the key points of two images,is performed by combining the local similarities and the geometric relations together using the highest confidence first method.Afterwards,a global similarity is calculated for object recognition.Experimental results on Coil-100 object database,which consists of 7200 images of 100 objects,are presented.When the numbers of templates vary from 4,8,18 to 36 for each object,and the remaining images compose the test sets,the object recognition rates are 95.75%,99.30%,100.0%and 100.0%,respectively.The excellent recognition performance is much better than those of the other cited references,which indicates that our approach is well-suited for appearance-based object recognition.展开更多
The 3-D characteristics of the water-air flow patterns in a corridor-shaped air-cushion surge chamber during hydraulic transients need to be considered in the shape optimization. To verify the reliability of the water...The 3-D characteristics of the water-air flow patterns in a corridor-shaped air-cushion surge chamber during hydraulic transients need to be considered in the shape optimization. To verify the reliability of the water-air two-phase model, namely, the volume of fluid model, the process of charging water into a closed air chamber is successfully simulated. Using the model, the 3-D flow characteristics under the load rejection and acceptance conditions within the air-cushion surge chamber of a specific hydro- power station are studied. The free surface waves, the flow patterns, and the pressure changes during the surge wave process are analyzed in detail. The longitudinal flow of water in the long corridor-shaped surge chamber is similar to the open channel flow with respect to the wave propagation, reflection and superposition characteristics. The lumped parameters of the 3-D numerical simulation agree with the results of a 1-D calculation of hydraulic transients in the whole water conveying system, which validates the 3-D method. The 3-D flow structures obtained can be applied to the shape optimization of the chamber.展开更多
On 22 nd May 2021(local time),an earthquake of M_(s)7.4 struck Maduo county in Qinghai Province,China.This was the largest earthquake in China since the 2008 Wenchuan earthquake.In this study,ascending/descending Sent...On 22 nd May 2021(local time),an earthquake of M_(s)7.4 struck Maduo county in Qinghai Province,China.This was the largest earthquake in China since the 2008 Wenchuan earthquake.In this study,ascending/descending Sentinel-1 and advanced land observation satellite-2(ALOS-2)synthetic aperture radar(SAR)images were used to derive the three-dimensional(3-D)coseismic displacements of this earthquake.We used the differential interferometric SAR(In SAR,DIn SAR),pixel offset-tracking(POT),multiple aperture In SAR(MAI),and burst overlap interferometry(BOI)methods to derive the displacement observations along the line-of-sight(LOS)and azimuth directions.To accurately mitigate the effect of ionospheric delay on the ALOS-2 DIn SAR observations,a polynomial fitting method was proposed to optimize range-spectrum-split-derived ionospheric phases.In addition,the 3-D displacement field was obtained by a strain model and variance component estimation(SM-VCE)method based on the high-quality SAR displacement observations.Results indicated that a left-lateral fault slip with the largest horizontal displacement of up to 2.4 m dominated this earthquake,and the small-magnitude vertical displacement with an alternating uplift/subsidence pattern along the fault trace was more concentrated in the near-fault regions.Comparison with the global navigation satellite system data indicated that the SM-VCE method can significantly improve the accuracy of the displacements compared to the classical weighted least squares method,and the incorporation of the BOI displacements can substantially benefit the accuracy of north-south displacement.In addition to the displacements,three coseismic strain invariants calculated based on the strain model parameters were also investigated.It was found that the eastern and western parts of the faults suffered more significant strains compared with the epicenter region.展开更多
Experimental study of the formation and propagation of three-dimensional (3D) faults is of great sig- nificance in the understanding of the propagation process developing from initial natural faults. In the study desc...Experimental study of the formation and propagation of three-dimensional (3D) faults is of great sig- nificance in the understanding of the propagation process developing from initial natural faults. In the study described in this paper, experimental investigations of 3D propagation processes of a type of surface fault are carried out under biaxial compression. The strain field near the surface fault is dy- namically measured and fully analyzed with a high-density Multi-Channel Digital Strain Gauge (MCDSG) and Digital Speckle Correlation Method (DSCM) based on the white-light image analysis. Simultane- ously the micro-fracture process involved in fault formation is observed by a 3D acoustic emission (AE) location system with a set of multi-channel whole-wave record equipment. The experimental results show that the 3D propagation process of surface fault differs greatly from that of the two-dimensional (2D) state and that a new more complicated type of 3D morphological characters and deformation mechanisms are produced. The 3D propagation process of surface faults may be divided into three stages: 1) the first stage of crack propagation initiated by wing cracks; 2) the conversion stage propa- gated by petal cracks; and 3) the second stage of crack propagation formed by shell-shaped fracture surface. The primary propagation patterns of the three stages are different. The corresponding defor- mation fields and micro-fracture distributions are likewise different. The fracture activities from petal cracks especially are of vital importance during surface fault propagation. This is also a key conversion state and marks an intrinsic difference between 2D-like and the 3D state in fault development.展开更多
文摘The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance.
文摘We developed a parallelized scheme of 3D finite difference (3DFD)with non-oniform staggered grid to simulate the eccentric borehole acoustic field with side-wall acoustic logging tools in open and cased wells. Higher accuracy and lower computation cost were achieved with this scheme for modeling such an asymmetric wave field generated by a high frequency source near or on the borehole wall. We also modeled the cases with and without considering the effects of the tool body. The simulation results demonstrated that the logging tool body would attenuate the direct waves but have only little influence on the interface waves in such a borehole condition. The effects of the tool body on the wave field were significant only when the contrast of the elastic properties between tool body and borehole fluid was large.
基金supported by the National Basic Research 973 Program of China (Grant 2014CB046905)the Natural Science Foundation of Jiangsu Province for Distinguished Young Scholars (Grant BK20150005)+1 种基金the Fundamental Research Funds for the Central Universities (China University of Mining and Technology) (Grant 2014XT03)the innovation research project for academic graduate of Jiangsu Province (Grant KYLX16_0536)
文摘In this paper, uniaxial compression tests were carried out on a series of composite rock specimens with different dip angles, which were made from two types of rock-like material with different strength. The acoustic emission technique was used to monitor the acoustic signal characteristics of composite rock specimens during the entire loading process. At the same time, an optical non-contact 3 D digital image correlation technique was used to study the evolution of axial strain field and the maximal strain field before and after the peak strength at different stress levels during the loading process. The effect of bedding plane inclination on the deformation and strength during uniaxial loading was analyzed. The methods of solving the elastic constants of hard and weak rock were described. The damage evolution process, deformation and failure mechanism, and failure mode during uniaxial loading were fully determined. The experimental results show that the θ = 0?–45?specimens had obvious plastic deformation during loading, and the brittleness of the θ = 60?–90?specimens gradually increased during the loading process. When the anisotropic angle θincreased from 0?to 90?, the peak strength, peak strain,and apparent elastic modulus all decreased initially and then increased. The failure mode of the composite rock specimen during uniaxial loading can be divided into three categories:tensile fracture across the discontinuities(θ = 0?–30?), slid-ing failure along the discontinuities(θ = 45?–75?), and tensile-split along the discontinuities(θ = 90?). The axial strain of the weak and hard rock layers in the composite rock specimen during the loading process was significantly different from that of the θ = 0?–45?specimens and was almost the same as that of the θ = 60?–90?specimens. As for the strain localization highlighted in the maximum principal strain field, the θ = 0?–30?specimens appeared in the rock matrix approximately parallel to the loading direction,while in the θ = 45?–90?specimens it appeared at the hard and weak rock layer interface.
文摘The 3-D seismic dataset is a key tool to analyze and understand the mechanism of structural and stratigraphic hydrocarbon(HC)trapping in the subsurface.Conventionally used subsurface seismic characterization methods for fractures are based on the theory of effective anisotropy medium.The aim of this work is to improve the structural images with dense sampling of 3-D survey to evaluate structural and stratigraphic models for reservoir development to predict reservoir quality.The present study of the Gullfaks Field,located in the Norwegian North Sea Gullfaks sector,identifies the shallowest structural elements.The steepness of westward structural dip decreases eastward during the Upper Jurassic to Lower Cretaceous deposition.Reservoir sands consist of the Middle Jurassic deltaic deposits and Lower Jurassic fluvial channel and delta plain deposits.Sediment supply steadily prevails on sea-level rise and the succession displays a regressive trend indicated by a good continuous stacking pattern.The key factor for the development of reservoirs in the Gullfaks Field is fault transmissibility with spatially distributed pressure.The majority of mapped faults with sand-to-sand contacts are non-sealing,which provide restriction for the HC flow between the fault blocks.The traps for HC accumulation occur between the post-rift and syn-rift strata,i.e.antiform set by extensional system,unconformity trap at the top of syndeposition,and structural trap due to normal faults.Overall reservoir quality in the studied area is generally excellent with average 35%porosity and permeability in the Darcy range.Our findings are useful to better understand the development of siliciclastic reservoirs in similar geological settings worldwide.
基金Project supported by the National Natural Science Foundation of China(Grant No.11174195)
文摘The creation and propagation of longitudinal acoustic phonons (LAPs) in high quality hematite thin films (α-Fe203) epitaxially grown on different substrates (BaTiO3, SrTiO3, and LaAlO3) are investigated using the femtosecond pump- probe technique. Transient reflection measurements (AR/R) indicate the photo-excited electron dynamics, and the initial decay less than 1 ps and the slow decay of -500 ps are attributed to the electron-LO phonon coupling and electron-hole nonradiative recombination, respectively. LAPs in α-Fe2O3 film can be created by ultrafast excitation of the ligand field state, such as the ligand field transitions under 800-nm excitation as well as the ligand to metal charge-transfer with 400- nm excitation. The strain modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.
文摘After the field equations and the snonumuoo conditions between the interfaces for 3D eddy current problems Under various gauges were discussed, it was pointed cut in this paper that using the magnetic vector potential A. the electric scalar potential and Coulomb gauge △ .A = 0 in eddy current regions and using the magntetic scalar potential Ω in the non-conducting regions are more suitable. All field equations, the boundary conditions, the interface continuity conditions and the corresponding variational principle of this method are also given
文摘为了提高混响室声场模拟能力,北京卫星环境工程研究所自研一套高声强声场模拟试验设备。文章介绍了该设备的行波管发声系统设计和消声降噪处理过程——行波终端设计以及声试验控制仪器的原理。经过调试试验验证,测量结果满足声压级165 d B行波声场的要求,行波管试验段性能良好,达到167.9 d B,消声道出口噪声能够满足环境模拟需求。
基金This paper is supported by the National Natural Science Foundation of China (Grant Nos. 40572063 and 40272051);the Fostering Plan Fund for Trans-Century Excellent Talents and the Project 111 (No. B07011).
文摘The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China. The deformation evolution, the structure of strain and stress fields and its ore-controlling effect in the Shangzhuang deposit are discussed in this paper. It is revealed that the deformation evolution has mainly undergone four phases: the early ductile deformation, the second NE-striking horizontal simple shear, the third NE-striking compression-shear and the final NW-striking compression. The mineralization happened during the third stage in which the maximum principal stress gradually transited from NE to NW. The 3-D numerical simulations of the stress field show that, on the condition that the maximum principal stress is NE-striking, the fracture development in the fault zone is favored, while when the maximum principal stress is NW-striking, the fault zone is relatively extensional and it is suitable for the influx and emplacement of ore-forming fluids. The compression-shear strain field during the mineralization is characterized by the λ-type structure, the positive flower structure, etc. Orebodies are mostly equidistantly located in the dilatational spaces, which are distributed in the integral compressional circumstances. And the dilatational spaces are developed where the fault attitude changes or shear joint systems develop. In the overall compression-shear stress field, the strain field bears self-similarity at multiple scales, including the orebody, ore deposit and orefield. The selfsimilarity of the structure comprises the subequidistant distribution of fractures at the same scale and the similar shape of the fractures at various scales. Yet, due to the special geological structure, the orebodies are mostly located in the hanging wall in the Shangzhuang deposit, which is different from most deposits in the Jiaodong gold province. Analyses of the ore-controlling stress and strain fields in the deposit provide an important basis for deposit seeking.
基金Supported by the National Natural Science Foundation of China (Grant No.50674098)the National Basic Research Program of China (973 Program) (Grant No.2007CB209601)
文摘The borehole acoustic reflection imaging logging is a newly developed acoustic logging method that has attracted many interests. These converted and reflected waves for imaging are usually mixed up with borehole guided waves and therefore difficult to be clearly identified. To improve the downhole tool design and develop more sophisticate data processing and interpretation algorithms,studies on precisely numerical modeling of the wave fields in the acoustic reflection imaging logging are neces-sary and critical. This paper developed a parallelized scheme of 3D finite difference (3DFD) with non-uniform staggered grid and PML absorbing boundary to simulate the acoustic wave fields in isotropic and anisotropic formations. Applications of this scheme to the typical cases of isotropic and anisot-ropic formations and comparison with the results from published analytical solutions have demon-strated the validation and efficiency of the scheme. Higher accuracy and lower computation cost (3.5 times faster than the conventional schemes) have been achieved with this scheme for modeling such a complex wave fields of 60 dB dynamic range with higher frequency (10 kHz). This simulating program provides a quantitative analytical means for studying acoustic reflection imaging tool and development of the data processing and interpretation methods.
基金This work was supported by the National Natural Science Foundation,China under Grant 5173000400.
文摘In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor(CR-PMSM),the effectiveness of two methods was studied on handling of problems concerned with non-uniform distribution of magnetic field along axial direction in CR-PMSM,which were sectional calculation(SC)method and three-dimensional finite element(3-D FE)method.On this basis,the influence of the axial displacement and dq-axis currents on the operating characteristics of axial magnetic force and torque is analyzed by using the 3-D FE model.Analysis results show that the axial magnetic force and torque decrease with the increase of axial displacement of the rotor,and the amplitude regularity of the axial magnetic force is affected by the d-axis current.A prototype machine is fabricated and tested,in order to validate the design theory.
文摘Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part has been given. The influences of source field period, the conductivity, the buried depth and the length of the conductor on the transfer functions were studied. The extrema of transfer functions appear at the center, the four corners and around the edges of conductor, and move with the edges. This feature demonstrates that around the edges are best places for transfer functions' observation.
基金Supported by National Natural Science Foundation of China (91026001)
文摘The InjectorⅡ, one of the two parallel injectors of the high-current superconducting proton driver linac for the China Accelerator-Driven System (C-ADS) project, is being designed and constructed by the Institute of Modern Physics. At present, the design work for the injector is almost finished. End-to-end simulation has been carried out using the TRACK multiparticle simulation code to check the match between each acceleration section and the performance of the injector as a whole. Moreover, multiparticle simulations with all kinds of errors and misalignments have been performed to define the requirements of each device. The simulation results indicate that the lattice design is robust. In this paper, the results of end-to-end simulation and error simulation with a 3-D field map are presented.
文摘The recognition of 3-D objects is quite a difficult task for computer vision systems.This paper presents a new object framework,which utilizes densely sampled grids with different resolutions to represent the local information of the input image.A Markov random field model is then created to model the geometric distribution of the object key nodes.Flexible matching,which aims to find the accurate correspondence map between the key points of two images,is performed by combining the local similarities and the geometric relations together using the highest confidence first method.Afterwards,a global similarity is calculated for object recognition.Experimental results on Coil-100 object database,which consists of 7200 images of 100 objects,are presented.When the numbers of templates vary from 4,8,18 to 36 for each object,and the remaining images compose the test sets,the object recognition rates are 95.75%,99.30%,100.0%and 100.0%,respectively.The excellent recognition performance is much better than those of the other cited references,which indicates that our approach is well-suited for appearance-based object recognition.
基金support by the National Natural Science Foundation of China(Grant Nos.51039005,50909076)
文摘The 3-D characteristics of the water-air flow patterns in a corridor-shaped air-cushion surge chamber during hydraulic transients need to be considered in the shape optimization. To verify the reliability of the water-air two-phase model, namely, the volume of fluid model, the process of charging water into a closed air chamber is successfully simulated. Using the model, the 3-D flow characteristics under the load rejection and acceptance conditions within the air-cushion surge chamber of a specific hydro- power station are studied. The free surface waves, the flow patterns, and the pressure changes during the surge wave process are analyzed in detail. The longitudinal flow of water in the long corridor-shaped surge chamber is similar to the open channel flow with respect to the wave propagation, reflection and superposition characteristics. The lumped parameters of the 3-D numerical simulation agree with the results of a 1-D calculation of hydraulic transients in the whole water conveying system, which validates the 3-D method. The 3-D flow structures obtained can be applied to the shape optimization of the chamber.
基金supported by the National Key Basic Research and Development Program of China(Grant No.2018YFC1503603)the National Natural Science Foundation of China(Grant No.42030112)+3 种基金the Nature Science Foundation of Hunan Province(Grant No.2020JJ2043)the Project of Innovation-driven Plan of Central South University(Grant No.2019CX007)the Fundamental Research Funds for the Central Universities of Central South University(Grant Nos.2018zzts684 and 2019zzts011)the Hunan Provincial Innovation Foundation For Postgraduate(Grant No.CX20190067)。
文摘On 22 nd May 2021(local time),an earthquake of M_(s)7.4 struck Maduo county in Qinghai Province,China.This was the largest earthquake in China since the 2008 Wenchuan earthquake.In this study,ascending/descending Sentinel-1 and advanced land observation satellite-2(ALOS-2)synthetic aperture radar(SAR)images were used to derive the three-dimensional(3-D)coseismic displacements of this earthquake.We used the differential interferometric SAR(In SAR,DIn SAR),pixel offset-tracking(POT),multiple aperture In SAR(MAI),and burst overlap interferometry(BOI)methods to derive the displacement observations along the line-of-sight(LOS)and azimuth directions.To accurately mitigate the effect of ionospheric delay on the ALOS-2 DIn SAR observations,a polynomial fitting method was proposed to optimize range-spectrum-split-derived ionospheric phases.In addition,the 3-D displacement field was obtained by a strain model and variance component estimation(SM-VCE)method based on the high-quality SAR displacement observations.Results indicated that a left-lateral fault slip with the largest horizontal displacement of up to 2.4 m dominated this earthquake,and the small-magnitude vertical displacement with an alternating uplift/subsidence pattern along the fault trace was more concentrated in the near-fault regions.Comparison with the global navigation satellite system data indicated that the SM-VCE method can significantly improve the accuracy of the displacements compared to the classical weighted least squares method,and the incorporation of the BOI displacements can substantially benefit the accuracy of north-south displacement.In addition to the displacements,three coseismic strain invariants calculated based on the strain model parameters were also investigated.It was found that the eastern and western parts of the faults suffered more significant strains compared with the epicenter region.
基金the National Basic Research Program of China (Grant No. 2004CB18405)Open Founds of State Key Laboratory of Earthquake Dynamics (Grant No. LED0501 and LED0502)
文摘Experimental study of the formation and propagation of three-dimensional (3D) faults is of great sig- nificance in the understanding of the propagation process developing from initial natural faults. In the study described in this paper, experimental investigations of 3D propagation processes of a type of surface fault are carried out under biaxial compression. The strain field near the surface fault is dy- namically measured and fully analyzed with a high-density Multi-Channel Digital Strain Gauge (MCDSG) and Digital Speckle Correlation Method (DSCM) based on the white-light image analysis. Simultane- ously the micro-fracture process involved in fault formation is observed by a 3D acoustic emission (AE) location system with a set of multi-channel whole-wave record equipment. The experimental results show that the 3D propagation process of surface fault differs greatly from that of the two-dimensional (2D) state and that a new more complicated type of 3D morphological characters and deformation mechanisms are produced. The 3D propagation process of surface faults may be divided into three stages: 1) the first stage of crack propagation initiated by wing cracks; 2) the conversion stage propa- gated by petal cracks; and 3) the second stage of crack propagation formed by shell-shaped fracture surface. The primary propagation patterns of the three stages are different. The corresponding defor- mation fields and micro-fracture distributions are likewise different. The fracture activities from petal cracks especially are of vital importance during surface fault propagation. This is also a key conversion state and marks an intrinsic difference between 2D-like and the 3D state in fault development.