Based on an avalanche photodiode（ APD） detecting array working in Geiger mode（ GM-APD）, a high-performance infrared sensor readout integrated circuit（ ROIC） used for infrared 3D（ three-dimensional） imaging is ...Based on an avalanche photodiode（ APD） detecting array working in Geiger mode（ GM-APD）, a high-performance infrared sensor readout integrated circuit（ ROIC） used for infrared 3D（ three-dimensional） imaging is proposed. The system mainly consists of three functional modules, including active quenching circuit（ AQC）, time-to-digital converter（ TDC） circuit and other timing controller circuit. Each AQC and TDC circuit together constitutes the pixel circuit. Under the cooperation with other modules, the current signal generated by the GM-APD sensor is detected by the AQC, and the photon time-of-flight（ TOF） is measured and converted to a digital signal output to achieve a better noise suppression and a higher detection sensitivity by the TDC. The ROIC circuit is fabricated by the CSMC 0. 5 μm standard CMOS technology. The array size is 8 × 8, and the center distance of two adjacent cells is 100μm. The measurement results of the chip showthat the performance of the circuit is good, and the chip can achieve 1 ns time resolution with a 250 MHz reference clock, and the circuit can be used in the array structure of the infrared detection system or focal plane array（ FPA）.展开更多
The regular pattern of temperature change in a coalfield fire area while the fire is being extinguished was studied. To determine the extinguishing effect, a series of linear, logarithmic, polynomial or exponential ma...The regular pattern of temperature change in a coalfield fire area while the fire is being extinguished was studied. To determine the extinguishing effect, a series of linear, logarithmic, polynomial or exponential mathematical regression models were constructed using the observed temperature data from the Xinjiang coalfield fire extinguishing project. The quadratic polynomial mathematical model had the best fit. A large coal fire oven was also used to simulate the coal fire extinguishing process. The same mathematical regression experiments were carried out on that observed data. The results verified that the quadratic polynomial mathematical model had the best fit. Therefore, a quadratic polynomial mathematical model is proposed to accurately model the temperature-time relationship in a coalfield fire area. An application to coalfield fire suppression shows that the deduced mathe-matical model can be used to predict the temperature conditions and to determine the effect of fire extinguishing, thereby helping to speed up the fire suppression process in the coalfield fire area.展开更多
A 3-D digital core describes the pore space microstructure of rocks. An X-ray micro CT scan is the most accurate and direct but costly method to obtain a 3-D digital core. In this study, we propose a hybrid method whi...A 3-D digital core describes the pore space microstructure of rocks. An X-ray micro CT scan is the most accurate and direct but costly method to obtain a 3-D digital core. In this study, we propose a hybrid method which combines sedimentation simulation and simulated annealing （SA） method to generate 3-D digital cores based on 2-D images of rocks. The method starts with the sedimentation simulation to build a 3-D digital core, which is the initial configuration for the SA method. We update the initial digital core using the SA method to match the auto-correlation function of the 2-D rock image and eventually build the final 3-D digital core. Compared with the typical SA method, the hybrid method has significantly reduced the computation time. Local porosity theory is applied to quantitatively compare the reconstructed 3-D digital cores with the X-ray micro CT 3-D images. The results indicate that the 3-D digital cores reconstructed by the hybrid method have homogeneity and geometric connectivity similar to those of the X-ray micro CT image. The formation factors and permeabilities of the reconstructed 3-D digital cores are estimated using the finite element method （FEM） and lattice Boltzmann method （LBM）, respectively. The simulated results are in good agreement with the experimental measurements. Comparison of the simulation results suggests that the digital cores reconstructed by the hybrid method more closely reflect the true transport properties than the typical SA method alone.展开更多
In this paper, we show that if Wmax 〈 6 for the Hamming code Ham （r, 2）, then all of the nonzero codewords of Ham （r, 2） are minimal and if Wrnax 〈 8 for the extended Hamming code Hfim （r, 2）, then all of the ...In this paper, we show that if Wmax 〈 6 for the Hamming code Ham （r, 2）, then all of the nonzero codewords of Ham （r, 2） are minimal and if Wrnax 〈 8 for the extended Hamming code Hfim （r, 2）, then all of the nonzero codewords ofHfim （r, 2） are minimal, where Wmax is the maximum nonzero weight in Ham （r, 2） and Hfim （r, 2）.展开更多
This study explores the tradeoff relationship between the number of initial attack firefighting resources and the level of fire ignition prevention efforts mitigating the probability of human-made fires in the Republi...This study explores the tradeoff relationship between the number of initial attack firefighting resources and the level of fire ignition prevention efforts mitigating the probability of human-made fires in the Republic of Korea,where most fires are caused by human activities.To examine this tradeoff relationship,we develop a hybrid model that combines a robust optimization model with a stochastic simulation model.The robust optimization minimizes the expected number of fires not receiving a pre-defined response,such as the number of firefighting resources that must arrive at the fire within half an hour,subject to budget constraints and uncertainty about the daily number and location of fires.The simulation model produces a set of fire scenarios in which a combination of number,location,ignition time,and intensity of fires occur.Results show that fire ignition prevention is as cost-effective as initial attack firefighting resources given the current budget in the Republic of Korea for reducing the expected number of fires not covered by the predefined response.The mixed policy of fire suppression and fire prevention may produce some gains in efficiency relative to the dominant policy of strong fire suppression strategies.展开更多
Tianjin Aerospace Long March Rocket Manufacturing Co.,Ltd.under CASC successfully completed the digital assembly of the first-stage hydrogen tank and oxygen tank and the inter-tank section of the LM-5 launch vehicle f...Tianjin Aerospace Long March Rocket Manufacturing Co.,Ltd.under CASC successfully completed the digital assembly of the first-stage hydrogen tank and oxygen tank and the inter-tank section of the LM-5 launch vehicle for its maiden flight.It is the first time that indigenous developed equipment,for digital assembly,was used formally in product assembly,展开更多
When aerodynamic braking works,the braking wings can change the flow field around the train,which may impact on the comfort and safety.Based on a sliding mesh,the pressure wave and flow field around high-speed trains ...When aerodynamic braking works,the braking wings can change the flow field around the train,which may impact on the comfort and safety.Based on a sliding mesh,the pressure wave and flow field around high-speed trains with aerodynamic braking are analyzed.By comparing three typical intersection situations,the pressure wave of a high-speed train during braking (with or without aerodynamic braking) is studied.The analyses indicate that the pressure wave around the high-speed train body will change while using the aerodynamic braking,causing several pressure pulses on the surface of crossing high-speed trains.The distances between the pressure pulses are equal to the longitudinal distances of the brake wings,but the magnitudes of the fluctuations are less than those induced by the head of crossing trains.During the crossing,a train without aerodynamic braking will not impact the crossing train.展开更多
In this paper, the effect of the imaginary circle diameter opi and the initial flow field on the aerodynamic field in a tangentially fired furnace was studied by numerical simulation and experiments in the cold model....In this paper, the effect of the imaginary circle diameter opi and the initial flow field on the aerodynamic field in a tangentially fired furnace was studied by numerical simulation and experiments in the cold model. Results show that merely reducing the imaginary circle diameter rki can not significantly reduce the rotatiollal diameter op in the range considered. The flow still rotates coullter-clockwise stably and does not change rotation direction when the direction of all jet axes are defiected suddenly to the opposite rotation direction by up to 5.4" in a countereclockwise llow field. It is the first time that the numerical sAnulation results were obtained which agreed quite well with this experimental phenomena qualitatively. The experimental data, i.e., the rotational diameter & and the maximum velocity on the syrnmetric central line of fUrnace Vm, are only a bit larger than the simulation results. It is shown that the initial flow field has an important influence on the aerodynamic field in the furnace. Other measures have to be taken as wel1 in order to reduce & to resist slagging and high temperature corrosion of furnace tubes. Moreover, a new kind of grid arrangement was proposed in this paper, which can reduce effectively the false diffosion at the exit zone of burner.展开更多
Based on the basic idea of zone modeling method, a two-layer zone model is developed and programmed to calculate the fire growth and smoke spread in a multi-room building subjected to a fire.The related predictiVe equ...Based on the basic idea of zone modeling method, a two-layer zone model is developed and programmed to calculate the fire growth and smoke spread in a multi-room building subjected to a fire.The related predictiVe equations, numerical simulation method and sub-models implemented in this model are concisely described. A set of experimental data from Cooper’s work at NIST for a two-room compatment fire are chosen for comparison with the model and program, and the numerical results fundamentally agree well with the experimental data. Then, an example of numerical calculation of a two-story building fire is presented, and the relevant output results are given and analyzed.展开更多
This work presents a numerical simulation of the flow field in a liquid propellant rocket engine chamber and exit nozzle using techniques to allow the results to be taken as starting points for designing those propuls...This work presents a numerical simulation of the flow field in a liquid propellant rocket engine chamber and exit nozzle using techniques to allow the results to be taken as starting points for designing those propulsive systems. This was done using a Finite Volume method simulating the different flow regimes which usually take place in those systems. As the flow field has regions ranging from the low subsonic to the supersonic regimes, the numerical code used, initially developed for commpressible flows only, was modified to work proficiently in the whole velocity range. It is well known that codes have been developed in CFD, for either compressible or incompressible flows, the joint treatment of both together being complex even today, given the small number of. references available in this area. Here an existing code for compressible flow was used and primitive variables, the pressure, the Cartesian components of the velocity and the temperature instead of the conserved variables were introduced in the Euler and Navier-Stokes equations. This was done to penult the treatment at any Mach number. Unstructured meshes with adaptive refinements were employed here. The convective terms were treated with upwind first and second order methods. The numerical stability was kept with artificial dissipation and in the spatial coverage one used a five stage Runge-Kutta scheme for the Fluid Mechanics and the VODE (Value of Ordinary Differential Equations) scheme along with the Chemkin II in the chemical reacting solution. During the development of this code simulating the flow in a rocket engine, comparison tests were made with several different types of internal and external flows, at different velocities, seeking to establish the confidence level of the techniques being used. These comparisons were done with existing theortical results and with other codes already validated and well acceptal by the CFD community.展开更多
Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion conditions.This paper presents an instrumentation system for the concurrent measurement of the temperature di...Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion conditions.This paper presents an instrumentation system for the concurrent measurement of the temperature distributionand soot concentration of flames developed on the two-color principle. This system consists of an endoscope,an optical assembly with optical filters, a CCD camera, a frame grabber and associated image processingsoftware. Experiments are performed on a methane-air combustor and the temperature fields and the soot concentrationscorresponding to the flame images are obtained. The results have demonstrated that the system is capableof performing on-line measurement of flame and temperature distribution, providing temporal and spatial characterizationof the combustion process. In addition, the combination of advanced optical sensing and digital imageprocessing technique can help to define the threshold by the analysis of the background noise. Furthermore, theutilization of the filter technique can enhance the image presentation effect to an extent.展开更多
In this work, a preliminary numerical model of the behavior of retro-reflective materials used as envelope coatings on street canyon buildings facades has been tested. Retro-reflective materials have a surface finish ...In this work, a preliminary numerical model of the behavior of retro-reflective materials used as envelope coatings on street canyon buildings facades has been tested. Retro-reflective materials have a surface finish that allows to reflect the solar radiation back in the same direction of the incident radiation. In the last years this kind of materials has been studied as buildings envelope coating for their potentials in the reduction of the UHI effect. As a matter of fact, the angular dependence of their optical-radiative response would help to mitigate the phenomenon of radiative entrapment due to the urban fabric environment. For this reason, an urban canyon was selected as the most common urban architecture to perform the analysis. A virtual retroreflective material has been simulated considering its response as almost diffusive but in the same direction of the incident radiation. The assessment of the energy advantages of the adoption of a virtual retro-reflective material as envelope coating is investigated by means of a numerical model developed in MATLAB and based on the Gebhart factors theory. The final purpose of the numerical model is the evaluation of the surfaces solar loads by a comparison between perfectly diffusive materials and RR materials used as fa？ades coating.展开更多
A phase-matched filtering technique is applied to extract fundamental mode signals from Rayleigh waves recorded at 62 digital seismic stations in the Yunnan and Sichuan regions.We use the fundamental mode of vibration...A phase-matched filtering technique is applied to extract fundamental mode signals from Rayleigh waves recorded at 62 digital seismic stations in the Yunnan and Sichuan regions.We use the fundamental mode of vibrations at two stations that are located on the same great circle as the focus to calculate an inter-station attenuation coefficient of the Rayleigh wave with periods between 0.40 and 80.64 s,and invert for the inter-station S-wave Q-factor (Qβ) at depths of 0-200 km.The results indicate that Qβ in Yunnan is 20-140,presenting a low Qβ background with apparent lateral variation.Taking the Honghe Fault as the boundary,Qβ of the crust is only 20 on the west side,extending to a depth of 120 km.The distribution of Qβ is consistent with large-scale Cenozoic volcanic and intrusive rocks in western Yunnan,implying that the crust and mantle are in the thermally active state.In the eastern Yunnan Block,east of the Xiaojiang Fault,Qβ in the upper 120 km is 140 in the south but only 20 in the north.Additionally,around the Dukou-Chuxiong in the mid-Yunnan Block,Qβ in the lithosphere is relatively high at 60-100,corresponding to a stiff crust.This is because the suture between the Indian and Eurasian plates reversed the tension in the rifting stage into the compression of orogenesis,leading to the closure of a gap in the crust.After some time,interstitial fluids gradually disappeared,resulting in a high velocity layer in the crust and low heat flow on the surface.The Yunnan region consists of an obvious block of elevated Qβ,distributed within the low background,consistent with the distribution of heat-flow values on the surface.The Honghe and Xiaojiang faults are tectonic boundaries in addition to being boundaries between regions of high and low crustal Qβ.The low Qβ is probably the result of crustal rupture and disturbance caused by strong earthquakes and the upwelling of hot substances along the deep fault zones.展开更多
基金The Natural Science Foundation of Jiangsu Province(No.BK2012559)Qing Lan Project of Jiangsu Province
文摘Based on an avalanche photodiode（ APD） detecting array working in Geiger mode（ GM-APD）, a high-performance infrared sensor readout integrated circuit（ ROIC） used for infrared 3D（ three-dimensional） imaging is proposed. The system mainly consists of three functional modules, including active quenching circuit（ AQC）, time-to-digital converter（ TDC） circuit and other timing controller circuit. Each AQC and TDC circuit together constitutes the pixel circuit. Under the cooperation with other modules, the current signal generated by the GM-APD sensor is detected by the AQC, and the photon time-of-flight（ TOF） is measured and converted to a digital signal output to achieve a better noise suppression and a higher detection sensitivity by the TDC. The ROIC circuit is fabricated by the CSMC 0. 5 μm standard CMOS technology. The array size is 8 × 8, and the center distance of two adjacent cells is 100μm. The measurement results of the chip showthat the performance of the circuit is good, and the chip can achieve 1 ns time resolution with a 250 MHz reference clock, and the circuit can be used in the array structure of the infrared detection system or focal plane array（ FPA）.
基金Project 50474031 supported by the National Natural Science Foundation of China
文摘The regular pattern of temperature change in a coalfield fire area while the fire is being extinguished was studied. To determine the extinguishing effect, a series of linear, logarithmic, polynomial or exponential mathematical regression models were constructed using the observed temperature data from the Xinjiang coalfield fire extinguishing project. The quadratic polynomial mathematical model had the best fit. A large coal fire oven was also used to simulate the coal fire extinguishing process. The same mathematical regression experiments were carried out on that observed data. The results verified that the quadratic polynomial mathematical model had the best fit. Therefore, a quadratic polynomial mathematical model is proposed to accurately model the temperature-time relationship in a coalfield fire area. An application to coalfield fire suppression shows that the deduced mathe-matical model can be used to predict the temperature conditions and to determine the effect of fire extinguishing, thereby helping to speed up the fire suppression process in the coalfield fire area.
基金sponsored by NSFC(Grant No.40574030)CNPC Research Project(Grant No.06A30102)
文摘A 3-D digital core describes the pore space microstructure of rocks. An X-ray micro CT scan is the most accurate and direct but costly method to obtain a 3-D digital core. In this study, we propose a hybrid method which combines sedimentation simulation and simulated annealing （SA） method to generate 3-D digital cores based on 2-D images of rocks. The method starts with the sedimentation simulation to build a 3-D digital core, which is the initial configuration for the SA method. We update the initial digital core using the SA method to match the auto-correlation function of the 2-D rock image and eventually build the final 3-D digital core. Compared with the typical SA method, the hybrid method has significantly reduced the computation time. Local porosity theory is applied to quantitatively compare the reconstructed 3-D digital cores with the X-ray micro CT 3-D images. The results indicate that the 3-D digital cores reconstructed by the hybrid method have homogeneity and geometric connectivity similar to those of the X-ray micro CT image. The formation factors and permeabilities of the reconstructed 3-D digital cores are estimated using the finite element method （FEM） and lattice Boltzmann method （LBM）, respectively. The simulated results are in good agreement with the experimental measurements. Comparison of the simulation results suggests that the digital cores reconstructed by the hybrid method more closely reflect the true transport properties than the typical SA method alone.
文摘In this paper, we show that if Wmax 〈 6 for the Hamming code Ham （r, 2）, then all of the nonzero codewords of Ham （r, 2） are minimal and if Wrnax 〈 8 for the extended Hamming code Hfim （r, 2）, then all of the nonzero codewords ofHfim （r, 2） are minimal, where Wmax is the maximum nonzero weight in Ham （r, 2） and Hfim （r, 2）.
基金supported by 2014 Yeungnam University Research Grant
文摘This study explores the tradeoff relationship between the number of initial attack firefighting resources and the level of fire ignition prevention efforts mitigating the probability of human-made fires in the Republic of Korea,where most fires are caused by human activities.To examine this tradeoff relationship,we develop a hybrid model that combines a robust optimization model with a stochastic simulation model.The robust optimization minimizes the expected number of fires not receiving a pre-defined response,such as the number of firefighting resources that must arrive at the fire within half an hour,subject to budget constraints and uncertainty about the daily number and location of fires.The simulation model produces a set of fire scenarios in which a combination of number,location,ignition time,and intensity of fires occur.Results show that fire ignition prevention is as cost-effective as initial attack firefighting resources given the current budget in the Republic of Korea for reducing the expected number of fires not covered by the predefined response.The mixed policy of fire suppression and fire prevention may produce some gains in efficiency relative to the dominant policy of strong fire suppression strategies.
文摘Tianjin Aerospace Long March Rocket Manufacturing Co.,Ltd.under CASC successfully completed the digital assembly of the first-stage hydrogen tank and oxygen tank and the inter-tank section of the LM-5 launch vehicle for its maiden flight.It is the first time that indigenous developed equipment,for digital assembly,was used formally in product assembly,
基金Project(No.2009BAG12A05-13) supported by the National Key Technology R&D Program of China
文摘When aerodynamic braking works,the braking wings can change the flow field around the train,which may impact on the comfort and safety.Based on a sliding mesh,the pressure wave and flow field around high-speed trains with aerodynamic braking are analyzed.By comparing three typical intersection situations,the pressure wave of a high-speed train during braking (with or without aerodynamic braking) is studied.The analyses indicate that the pressure wave around the high-speed train body will change while using the aerodynamic braking,causing several pressure pulses on the surface of crossing high-speed trains.The distances between the pressure pulses are equal to the longitudinal distances of the brake wings,but the magnitudes of the fluctuations are less than those induced by the head of crossing trains.During the crossing,a train without aerodynamic braking will not impact the crossing train.
文摘In this paper, the effect of the imaginary circle diameter opi and the initial flow field on the aerodynamic field in a tangentially fired furnace was studied by numerical simulation and experiments in the cold model. Results show that merely reducing the imaginary circle diameter rki can not significantly reduce the rotatiollal diameter op in the range considered. The flow still rotates coullter-clockwise stably and does not change rotation direction when the direction of all jet axes are defiected suddenly to the opposite rotation direction by up to 5.4" in a countereclockwise llow field. It is the first time that the numerical sAnulation results were obtained which agreed quite well with this experimental phenomena qualitatively. The experimental data, i.e., the rotational diameter & and the maximum velocity on the syrnmetric central line of fUrnace Vm, are only a bit larger than the simulation results. It is shown that the initial flow field has an important influence on the aerodynamic field in the furnace. Other measures have to be taken as wel1 in order to reduce & to resist slagging and high temperature corrosion of furnace tubes. Moreover, a new kind of grid arrangement was proposed in this paper, which can reduce effectively the false diffosion at the exit zone of burner.
文摘Based on the basic idea of zone modeling method, a two-layer zone model is developed and programmed to calculate the fire growth and smoke spread in a multi-room building subjected to a fire.The related predictiVe equations, numerical simulation method and sub-models implemented in this model are concisely described. A set of experimental data from Cooper’s work at NIST for a two-room compatment fire are chosen for comparison with the model and program, and the numerical results fundamentally agree well with the experimental data. Then, an example of numerical calculation of a two-story building fire is presented, and the relevant output results are given and analyzed.
文摘This work presents a numerical simulation of the flow field in a liquid propellant rocket engine chamber and exit nozzle using techniques to allow the results to be taken as starting points for designing those propulsive systems. This was done using a Finite Volume method simulating the different flow regimes which usually take place in those systems. As the flow field has regions ranging from the low subsonic to the supersonic regimes, the numerical code used, initially developed for commpressible flows only, was modified to work proficiently in the whole velocity range. It is well known that codes have been developed in CFD, for either compressible or incompressible flows, the joint treatment of both together being complex even today, given the small number of. references available in this area. Here an existing code for compressible flow was used and primitive variables, the pressure, the Cartesian components of the velocity and the temperature instead of the conserved variables were introduced in the Euler and Navier-Stokes equations. This was done to penult the treatment at any Mach number. Unstructured meshes with adaptive refinements were employed here. The convective terms were treated with upwind first and second order methods. The numerical stability was kept with artificial dissipation and in the spatial coverage one used a five stage Runge-Kutta scheme for the Fluid Mechanics and the VODE (Value of Ordinary Differential Equations) scheme along with the Chemkin II in the chemical reacting solution. During the development of this code simulating the flow in a rocket engine, comparison tests were made with several different types of internal and external flows, at different velocities, seeking to establish the confidence level of the techniques being used. These comparisons were done with existing theortical results and with other codes already validated and well acceptal by the CFD community.
基金the National High Technology Research and Development of China (863 Program) (2006AA05A103)the National Natural Science Fund (grant No. 40501017, grant No. 50706053)
文摘Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion conditions.This paper presents an instrumentation system for the concurrent measurement of the temperature distributionand soot concentration of flames developed on the two-color principle. This system consists of an endoscope,an optical assembly with optical filters, a CCD camera, a frame grabber and associated image processingsoftware. Experiments are performed on a methane-air combustor and the temperature fields and the soot concentrationscorresponding to the flame images are obtained. The results have demonstrated that the system is capableof performing on-line measurement of flame and temperature distribution, providing temporal and spatial characterizationof the combustion process. In addition, the combination of advanced optical sensing and digital imageprocessing technique can help to define the threshold by the analysis of the background noise. Furthermore, theutilization of the filter technique can enhance the image presentation effect to an extent.
文摘In this work, a preliminary numerical model of the behavior of retro-reflective materials used as envelope coatings on street canyon buildings facades has been tested. Retro-reflective materials have a surface finish that allows to reflect the solar radiation back in the same direction of the incident radiation. In the last years this kind of materials has been studied as buildings envelope coating for their potentials in the reduction of the UHI effect. As a matter of fact, the angular dependence of their optical-radiative response would help to mitigate the phenomenon of radiative entrapment due to the urban fabric environment. For this reason, an urban canyon was selected as the most common urban architecture to perform the analysis. A virtual retroreflective material has been simulated considering its response as almost diffusive but in the same direction of the incident radiation. The assessment of the energy advantages of the adoption of a virtual retro-reflective material as envelope coating is investigated by means of a numerical model developed in MATLAB and based on the Gebhart factors theory. The final purpose of the numerical model is the evaluation of the surfaces solar loads by a comparison between perfectly diffusive materials and RR materials used as fa？ades coating.
基金supported by National Natural Science Fundation of China (Grant No. U0933602)Professional Projects of the Chinese Seismological Bureau (Grant No. 200808061)
文摘A phase-matched filtering technique is applied to extract fundamental mode signals from Rayleigh waves recorded at 62 digital seismic stations in the Yunnan and Sichuan regions.We use the fundamental mode of vibrations at two stations that are located on the same great circle as the focus to calculate an inter-station attenuation coefficient of the Rayleigh wave with periods between 0.40 and 80.64 s,and invert for the inter-station S-wave Q-factor (Qβ) at depths of 0-200 km.The results indicate that Qβ in Yunnan is 20-140,presenting a low Qβ background with apparent lateral variation.Taking the Honghe Fault as the boundary,Qβ of the crust is only 20 on the west side,extending to a depth of 120 km.The distribution of Qβ is consistent with large-scale Cenozoic volcanic and intrusive rocks in western Yunnan,implying that the crust and mantle are in the thermally active state.In the eastern Yunnan Block,east of the Xiaojiang Fault,Qβ in the upper 120 km is 140 in the south but only 20 in the north.Additionally,around the Dukou-Chuxiong in the mid-Yunnan Block,Qβ in the lithosphere is relatively high at 60-100,corresponding to a stiff crust.This is because the suture between the Indian and Eurasian plates reversed the tension in the rifting stage into the compression of orogenesis,leading to the closure of a gap in the crust.After some time,interstitial fluids gradually disappeared,resulting in a high velocity layer in the crust and low heat flow on the surface.The Yunnan region consists of an obvious block of elevated Qβ,distributed within the low background,consistent with the distribution of heat-flow values on the surface.The Honghe and Xiaojiang faults are tectonic boundaries in addition to being boundaries between regions of high and low crustal Qβ.The low Qβ is probably the result of crustal rupture and disturbance caused by strong earthquakes and the upwelling of hot substances along the deep fault zones.
