There are various faults in northern and southern margins of Torbat-e-Jam-Fariman plain which show the probability of enormous earthquake in the future.In present study the geomorphic indices contain Asymmetry Functio...There are various faults in northern and southern margins of Torbat-e-Jam-Fariman plain which show the probability of enormous earthquake in the future.In present study the geomorphic indices contain Asymmetry Function(Af),Sinuosity of mountain front(Smf),Valley floor index(Vf),Hypsometric index(Hi),Mean Axial slope of channel index(MASC)and Drainage Basin Shape(Bs),have been utilized to determine the relative tectonic activity index(IAT)to recognize,eventually,the geo-structural model of the study area.Faults and folds control the geo-structural activities of the study area,and the geomorphic indices are being affected in consequence of their activities.The intensity of these activities is different throughout the plain.There are many geomorphic evidences,related to active transform fault which are detectable all over the study area such as deviated rivers,quaternary sediments transformation,fault traces.Therefore,recognition of geo-structural model of the study area is extremely vital.Field study,then,approved the results of geomorphic indices calculation in determining the geo-structural model of the study area.Results depicted that the geostructural model of the study area is a kind of Horsetail splay form which is in accordance to the relative tectonic activity of the study area.Based on the above mentioned results it can be predicted that the splays are the trail of Neyshabour fault.展开更多
Extrapolation of implosion performance between different laser energy scales is investigated for indirect drive through a semi-hydroequivalent design.Since radiation transport is non-hydro-equivalent,the peak radiatio...Extrapolation of implosion performance between different laser energy scales is investigated for indirect drive through a semi-hydroequivalent design.Since radiation transport is non-hydro-equivalent,the peak radiation temperature of the hohlraum and the ablation velocity of the capsule ablator are not scale-invariant when the sizes of the hohlraum and the capsule are scale-varied.A semi-hydro-equivalent design method that keeps the implosion velocity V_(i),adiabat α_(F),and P_(L)/R_(hc)^(2) (where P_(L) is the laser power and R_(hc) is the hohlraum and capsule scale length)scale-invariant,is proposed to create hydrodynamically similar implosions.The semi-hydro-equivalent design and the scaled implosion performance are investigated for the 100 kJ Laser Facility(100 kJ-scale)and the National Ignition Facility(NIF-scale)with about 2 MJ laser energy.It is found that the one-dimensional implosion performance is approximately hydro-equivalent when V_(i) and α_(F) are kept the same.Owing to the non-hydro-equivalent radiation transport,the yield-over-clean without α-particle heating(YOC_(noα))is slightly lower at 100 kJ-scale than at NIF-scale for the same scaled radiation asymmetry or the same initial perturbation of the hydrodynamic instability.The overall scaled two-dimensional implosion performance is slightly lower at 100 kJ-scale.The general Lawson criterion factor scales asχ_(noα) ^(2D)∼S^(1.06±0.04)(where S is the scale-variation factor)for the semi-hydro-equivalent implosion design with a moderate YOC_(noα).Our study indicates that χ_(noα)≈0.379 is the minimum requirement for the 100 kJ-scale implosion to demonstrate the ability to achieve marginal ignition at NIF-scale.展开更多
Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high-Tc superconductors.In iron-based superconductors,spin excitations at low energy range,especially the spin-resona...Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high-Tc superconductors.In iron-based superconductors,spin excitations at low energy range,especially the spin-resonance mode at ER~5kBTc,are important for understanding the superconductivity.Here,we use inelastic neutron scattering(INS)to investigate the symmetry and in-plane wave-vector dependence of low-energy spin excitations in uniaxial-strain detwinned Fe Se.The low-energy spin excitations(E<10 meV)appear mainly at Q=(±1,0)in the superconducting state(T9K)and the nematic state(T90 K),confirming the constant C_(2) rotational symmetry and ruling out the C_(4) mode at E≈3 meV reported in a prior INS study.Moreover,our results reveal an isotropic spin resonance in the superconducting state,which is consistent with the s±wave pairing symmetry.At slightly higher energy,low-energy spin excitations become highly anisotropic.The full width at half maximum of spin excitations is elongated along the transverse direction.The Q-space isotropic spin resonance and highly anisotropic low-energy spin excitations could arise from dyz intra-orbital selective Fermi surface nesting between the hole pocket aroundΓpoint and the electron pockets centered at MX point.展开更多
China Sees Rising Retail Sales in Q1 China’s retail sales of consumer goods,a major indicator of the country’s consumption strength,climbed 4.7 percent year on year in the first quarter of 2024.The figure was slight...China Sees Rising Retail Sales in Q1 China’s retail sales of consumer goods,a major indicator of the country’s consumption strength,climbed 4.7 percent year on year in the first quarter of 2024.The figure was slightly lower than the 5.5 percent rise registered during the January-February period,according to data from the National Bureau of Statistics(NBS).展开更多
The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the gr...The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the grain size of the primary α phase in the slurry manufactured are researched. The results indicate that the slurry with particle-like and rosette-like primary α phases can be prepared by low superheat pouring and slight electromagnetic stirring from liquid A356 alloy grain-refined, in which the pouring temperature can be suitably raised. Compared with the A356 samples without grain refining, the grain size and particle morphology of primary α phase as well as the distribution of the grain with particle-like or rosette-like along radial in the ingot in A356 are markedly improved by grain refining.展开更多
A slight interfacial reaction in squeeze-cast SiCp/6061AI composites has been studied. It is found that this kind of reaction has a particular effect on the mechanical properties of the composites. The results of fie-...A slight interfacial reaction in squeeze-cast SiCp/6061AI composites has been studied. It is found that this kind of reaction has a particular effect on the mechanical properties of the composites. The results of fie-cure tests show that this reaction in the composites obviously increases the elastic properties, but is not beneficial to the fracture strength and ductility.This phenomenon can be interpreted in terms of two different micromechanisms which have been analyzed using TEM and HREM observations, acoustic emission (AE) technique and SEM fractography. In addition, a new method of SiC surface modification which can control the interface state is initially presented.展开更多
By analyzing the characteristics of low Mach number perfect gas flows, a novel Slightly Compressible Model (SCM) for low Mach number perect gas flows is derived. In view of numerical calculations, this model is proved...By analyzing the characteristics of low Mach number perfect gas flows, a novel Slightly Compressible Model (SCM) for low Mach number perect gas flows is derived. In view of numerical calculations, this model is proved very efficient, for it is kept within thep-v frame but does not have to satisfy the time consuming divergence-free condition in order to get the incompressible Navier-Stokes equation solution. Writing the equations in the form of conservation laws, we have derived the characteristic systems which are necessary for numerical calculations. A cell-centered finite-volume method with flux difference upwind-biased schemes is used for the equation solutions and a new Exact Newton Relaxation (ENR) implicit method is developed. Various computed results are presented to validate the present model. Laminar flow solutions over a circular cylinder with wake developing and vortex shedding are presented. Results for inviscid flow over a sphere are compared in excellent agreement with the exact analytic incompressible solution. Three-dimensional viscous flow solutions over sphere and prolate spheroid are also calculated and compared well with experiments and other incompressible solutions. Finally, good convergent performances are shown for sphere viscous flows.展开更多
The impact of increased shading stress on agronomic traits,photosynthetic performance and antioxidants activities in leaves of two soybeans cultivars(D16 and E93)was studied.Soybean seedlings were grown in pots and ex...The impact of increased shading stress on agronomic traits,photosynthetic performance and antioxidants activities in leaves of two soybeans cultivars(D16 and E93)was studied.Soybean seedlings were grown in pots and exposed to no shade(S0),slight shade(S1),moderate shade(S2),and heavy shade(S3).Our findings showed that under the S3 in both cultivars,leaf fresh weight(LFW),specific leaf area(SLA)and leaf thickness decreased signifiantly,accompanied by a reduction in photochemical parameters including the maximum quantum yield(Fv/Fm)and electron transport rate(ETR).Furthermore,compared to SO,S1 significantly increased the ETR,sucrose content and the activity of catalase(CAT)in both D16 and E93 cultivars while S2 and S3 decreased the activity.However,under all treatments of shading stress,the antioxidant activities of superoxide dismutase(SOD)and peroxidase(POD)were lowered in both cultivars.Such morphological and physiological plasticity to adapt S1 compensates for the decrease in biomass and leads to seed weight compared to that obtained with an amount of normal light.Through configuring the space in the intercropping systems,S1 could be helpful for optimum growth and yield.Redesigning photosynthesis through S1 for the intercropping systems could be a smart approach.展开更多
The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids (SS). A small-scale fixed film biological aerated filter (BAF) process was used to treat the wastewater. Th...The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids (SS). A small-scale fixed film biological aerated filter (BAF) process was used to treat the wastewater. The influences of hydraulic retention time (HRT), air/water volume flow ratio and backwashing cycle on treatment efficiencies were investigated. The wastewater was treated by the BAF process under optimal conditions: the HRT of 1.0 h, the air/water volume flow ratio of about 5 : 1 and the backwashing cycle of every 4-7 days. The results showed that the average removal efficiency of COD, oil pollutants and SS was 84.5%, 94.0% and 83.4%, respectively. And the average effluent concentration of COD, oil pollutants and SS was 12.5, 0.27, 14.5 mg·L^-1, respectively. The experimental results demonstrated that the BAF process is a suitable and highly efficient method to treat the wastewater.展开更多
Over the last decades,geo-structures are experiencing a rapid development in China.The potential risks inherent in the huge amount of construction and asset operation projects in China were well managed in the major p...Over the last decades,geo-structures are experiencing a rapid development in China.The potential risks inherent in the huge amount of construction and asset operation projects in China were well managed in the major project,i.e.the project of Shanghai Yangtze tunnel in 2002.Since then,risk assessment of geostructures has been gradually developed from a qualitative manner to a quantitative manner.However,the current practices of risk management have been paid considerable attention to the assessment,but little on risk control.As a result,the responses to risks occurrences after a comprehensive assessment are basically too late.In this paper,a smart system for risk sensing incorporating the wireless sensor network(WSN) on-site visualization techniques and the resilience-based repair strategy was proposed.The merit of this system is the real-time monitoring for geo-structural performance and dynamic pre-warning for safety of on-site workers.The sectional convergence,joint opening,and seepage of segmental lining of shield tunnel were monitored by the micro-electro-mechanical systems(MEMS) based sensors.The light emitting diode(LED) coupling with the above WSN system was used to indicate different risk levels on site.By sensing the risks and telling the risks in real time,the geo-risks could be controlled and the safety of geo-structures could be assured to a certain degree.Finally,a resilience-based analysis model was proposed for designing the repair strategy by using the measured data from the WSN system.The application and efficiency of this system have been validated by two cases including Shanghai metro tunnel and underwater road tunnel.展开更多
[Objective] The study aimed to discuss the application of a stereo constructed wetland to the treatment of slightly polluted source water. [Method] In this study, a new stereo constructed wetland mode was put forward,...[Objective] The study aimed to discuss the application of a stereo constructed wetland to the treatment of slightly polluted source water. [Method] In this study, a new stereo constructed wetland mode was put forward, and a pilot project of water ecological purification in Xinsheng River, the diversion channel of Shijiuyang Waterwork in Jiaxing City, were analyzed. Afterwards, the impact factors of water purification by the technology were discussed from water quality and quantity, season and climate, species configuration, management and maintenance. [Result] Under three different hydraulic loading conditions, the pilot project effectively improved water SD and DO level, and reduced SS, CODCr, NH3-N, TN and TP significantly in summer and autumn, so that effluent water quality reached surface water standard at Grade III. [Conclusion] The stereo constructed wetland mode composed of constructed wetland and underwater forest used to treat slightly polluted source water is feasible and has a good promotion prospect.展开更多
A slightly acidic hot spring named "Female Tower"(t=73.5°C, pH=6.64) is located in the Jifei Geothermal Field, Yunnan Province, southwestern China. The precipitates in the hot spring are composed of large amo...A slightly acidic hot spring named "Female Tower"(t=73.5°C, pH=6.64) is located in the Jifei Geothermal Field, Yunnan Province, southwestern China. The precipitates in the hot spring are composed of large amounts of calcite, aragonite and sulfur. Scanning electron microscopy(SEM) analyses reveal that the microbial mats were formed from various coccoid or rod-shaped filamentous microbes. Transmission electron microscopy(TEM) shows that the intracellular sulfur granules are commonly associated with these microbes. A culture-independent molecular phylogenetic analysis demonstrates that the majority of the bacteria in the spring are sulfur-oxidizing bacteria. In the spring water, H2S concentration is up to 60 ppm, while SO4-(2-) concentration is only about 10 ppm. We speculate that H2S might derive from sulfur-oxidizing bacteria in this hot spring water, leading to the intracellular formation of sulfur granules. Meanwhile, this reaction increased the p H in the micronscale microdomains, which fosters the precipitation of calcium carbonate in the microbial mats. The results of this study indicate that the sulfur-oxidizing bacteria might play an important role in calcium carbonate precipitation in slightly acidic hot spring environments.展开更多
In this study, a slightly curved Euler Bernoulli beam carrying a concentrated mass was handled. The beam was resting on an elastic foundation and simply supported at both ends. Effects of the concentrated mass on nonl...In this study, a slightly curved Euler Bernoulli beam carrying a concentrated mass was handled. The beam was resting on an elastic foundation and simply supported at both ends. Effects of the concentrated mass on nonlin- ear vibrations were investigated. Sinusoidal and parabolic type functions were used as curvature functions. Equations of motion have cubic nonlinearities because of elongations during vibrations. Damping and harmonic excitation terms were added to the equations of motion. Method of mul- tiple scales, a perturbation technique, was used for solving integro-differential equation analytically. Natural frequen- cies were calculated exactly for different mass ratios, mass locations, curvature functions, and linear elastic foundation coefficients. Amplitude-phase modulation equations were found by considering primary resonance case. Effects of nonlinear terms on natural frequencies were calculated. Frequency-amplitude and frequency-response graphs were plotted. Finally effects of concentrated mass and chosen curvature function on nonlinear vibrations were investigated.展开更多
Rich oxygen-biological activated carbon(RO-BAC)method developed from traditional BAC method is a sys-tem in which high pressure is applied to improve the oxy-gen concentration of the influent.Experiment withwastewater...Rich oxygen-biological activated carbon(RO-BAC)method developed from traditional BAC method is a sys-tem in which high pressure is applied to improve the oxy-gen concentration of the influent.Experiment withwastewater and the slightly deteriorated raw water showsthe system is an effective option for advanced treatmentof industry wastewater and pretreatment of slightly dete-riorated raw water.The experiment results and the in-fluential factors are discussed in this paper.展开更多
文摘There are various faults in northern and southern margins of Torbat-e-Jam-Fariman plain which show the probability of enormous earthquake in the future.In present study the geomorphic indices contain Asymmetry Function(Af),Sinuosity of mountain front(Smf),Valley floor index(Vf),Hypsometric index(Hi),Mean Axial slope of channel index(MASC)and Drainage Basin Shape(Bs),have been utilized to determine the relative tectonic activity index(IAT)to recognize,eventually,the geo-structural model of the study area.Faults and folds control the geo-structural activities of the study area,and the geomorphic indices are being affected in consequence of their activities.The intensity of these activities is different throughout the plain.There are many geomorphic evidences,related to active transform fault which are detectable all over the study area such as deviated rivers,quaternary sediments transformation,fault traces.Therefore,recognition of geo-structural model of the study area is extremely vital.Field study,then,approved the results of geomorphic indices calculation in determining the geo-structural model of the study area.Results depicted that the geostructural model of the study area is a kind of Horsetail splay form which is in accordance to the relative tectonic activity of the study area.Based on the above mentioned results it can be predicted that the splays are the trail of Neyshabour fault.
基金funded by the National Natural Science Foundation of China(NSFC)under Grant No.11975056Science Challenge Project(SCP)No.TZ2016005。
文摘Extrapolation of implosion performance between different laser energy scales is investigated for indirect drive through a semi-hydroequivalent design.Since radiation transport is non-hydro-equivalent,the peak radiation temperature of the hohlraum and the ablation velocity of the capsule ablator are not scale-invariant when the sizes of the hohlraum and the capsule are scale-varied.A semi-hydro-equivalent design method that keeps the implosion velocity V_(i),adiabat α_(F),and P_(L)/R_(hc)^(2) (where P_(L) is the laser power and R_(hc) is the hohlraum and capsule scale length)scale-invariant,is proposed to create hydrodynamically similar implosions.The semi-hydro-equivalent design and the scaled implosion performance are investigated for the 100 kJ Laser Facility(100 kJ-scale)and the National Ignition Facility(NIF-scale)with about 2 MJ laser energy.It is found that the one-dimensional implosion performance is approximately hydro-equivalent when V_(i) and α_(F) are kept the same.Owing to the non-hydro-equivalent radiation transport,the yield-over-clean without α-particle heating(YOC_(noα))is slightly lower at 100 kJ-scale than at NIF-scale for the same scaled radiation asymmetry or the same initial perturbation of the hydrodynamic instability.The overall scaled two-dimensional implosion performance is slightly lower at 100 kJ-scale.The general Lawson criterion factor scales asχ_(noα) ^(2D)∼S^(1.06±0.04)(where S is the scale-variation factor)for the semi-hydro-equivalent implosion design with a moderate YOC_(noα).Our study indicates that χ_(noα)≈0.379 is the minimum requirement for the 100 kJ-scale implosion to demonstrate the ability to achieve marginal ignition at NIF-scale.
基金Beijing Normal University was supported by the Fundamental Research Funds for the Central Universitiesthe National Key Projects for Research and Development of China(No.2021YFA1400400)+1 种基金the National Natural Science Foundation of China(Grant Nos.12174029 and 11922402)the neutron beamtimes from J-PARC(Proposal No.2019A0002)。
文摘Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high-Tc superconductors.In iron-based superconductors,spin excitations at low energy range,especially the spin-resonance mode at ER~5kBTc,are important for understanding the superconductivity.Here,we use inelastic neutron scattering(INS)to investigate the symmetry and in-plane wave-vector dependence of low-energy spin excitations in uniaxial-strain detwinned Fe Se.The low-energy spin excitations(E<10 meV)appear mainly at Q=(±1,0)in the superconducting state(T9K)and the nematic state(T90 K),confirming the constant C_(2) rotational symmetry and ruling out the C_(4) mode at E≈3 meV reported in a prior INS study.Moreover,our results reveal an isotropic spin resonance in the superconducting state,which is consistent with the s±wave pairing symmetry.At slightly higher energy,low-energy spin excitations become highly anisotropic.The full width at half maximum of spin excitations is elongated along the transverse direction.The Q-space isotropic spin resonance and highly anisotropic low-energy spin excitations could arise from dyz intra-orbital selective Fermi surface nesting between the hole pocket aroundΓpoint and the electron pockets centered at MX point.
文摘China Sees Rising Retail Sales in Q1 China’s retail sales of consumer goods,a major indicator of the country’s consumption strength,climbed 4.7 percent year on year in the first quarter of 2024.The figure was slightly lower than the 5.5 percent rise registered during the January-February period,according to data from the National Bureau of Statistics(NBS).
基金financially supported by National High Technical Research and Development Program of China(No.G2002AA336080)National Natural Science Foundation of China(No.50374012)Natural Science Foundation of Jiangxi Province(No.0650047).
文摘The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the grain size of the primary α phase in the slurry manufactured are researched. The results indicate that the slurry with particle-like and rosette-like primary α phases can be prepared by low superheat pouring and slight electromagnetic stirring from liquid A356 alloy grain-refined, in which the pouring temperature can be suitably raised. Compared with the A356 samples without grain refining, the grain size and particle morphology of primary α phase as well as the distribution of the grain with particle-like or rosette-like along radial in the ingot in A356 are markedly improved by grain refining.
文摘A slight interfacial reaction in squeeze-cast SiCp/6061AI composites has been studied. It is found that this kind of reaction has a particular effect on the mechanical properties of the composites. The results of fie-cure tests show that this reaction in the composites obviously increases the elastic properties, but is not beneficial to the fracture strength and ductility.This phenomenon can be interpreted in terms of two different micromechanisms which have been analyzed using TEM and HREM observations, acoustic emission (AE) technique and SEM fractography. In addition, a new method of SiC surface modification which can control the interface state is initially presented.
基金The project supported by the Basic Research on Frontier Problems in Fluid and Aerodynamics in Chinathe National Natural Science Foundation of China (19772069)
文摘By analyzing the characteristics of low Mach number perfect gas flows, a novel Slightly Compressible Model (SCM) for low Mach number perect gas flows is derived. In view of numerical calculations, this model is proved very efficient, for it is kept within thep-v frame but does not have to satisfy the time consuming divergence-free condition in order to get the incompressible Navier-Stokes equation solution. Writing the equations in the form of conservation laws, we have derived the characteristic systems which are necessary for numerical calculations. A cell-centered finite-volume method with flux difference upwind-biased schemes is used for the equation solutions and a new Exact Newton Relaxation (ENR) implicit method is developed. Various computed results are presented to validate the present model. Laminar flow solutions over a circular cylinder with wake developing and vortex shedding are presented. Results for inviscid flow over a sphere are compared in excellent agreement with the exact analytic incompressible solution. Three-dimensional viscous flow solutions over sphere and prolate spheroid are also calculated and compared well with experiments and other incompressible solutions. Finally, good convergent performances are shown for sphere viscous flows.
基金Funded by the National Key Research and Development Program of China(2018YFD1000905).
文摘The impact of increased shading stress on agronomic traits,photosynthetic performance and antioxidants activities in leaves of two soybeans cultivars(D16 and E93)was studied.Soybean seedlings were grown in pots and exposed to no shade(S0),slight shade(S1),moderate shade(S2),and heavy shade(S3).Our findings showed that under the S3 in both cultivars,leaf fresh weight(LFW),specific leaf area(SLA)and leaf thickness decreased signifiantly,accompanied by a reduction in photochemical parameters including the maximum quantum yield(Fv/Fm)and electron transport rate(ETR).Furthermore,compared to SO,S1 significantly increased the ETR,sucrose content and the activity of catalase(CAT)in both D16 and E93 cultivars while S2 and S3 decreased the activity.However,under all treatments of shading stress,the antioxidant activities of superoxide dismutase(SOD)and peroxidase(POD)were lowered in both cultivars.Such morphological and physiological plasticity to adapt S1 compensates for the decrease in biomass and leads to seed weight compared to that obtained with an amount of normal light.Through configuring the space in the intercropping systems,S1 could be helpful for optimum growth and yield.Redesigning photosynthesis through S1 for the intercropping systems could be a smart approach.
基金Supported by the Foundation of Science and Technology Project of Guangdong Province (2004B33301001)
文摘The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids (SS). A small-scale fixed film biological aerated filter (BAF) process was used to treat the wastewater. The influences of hydraulic retention time (HRT), air/water volume flow ratio and backwashing cycle on treatment efficiencies were investigated. The wastewater was treated by the BAF process under optimal conditions: the HRT of 1.0 h, the air/water volume flow ratio of about 5 : 1 and the backwashing cycle of every 4-7 days. The results showed that the average removal efficiency of COD, oil pollutants and SS was 84.5%, 94.0% and 83.4%, respectively. And the average effluent concentration of COD, oil pollutants and SS was 12.5, 0.27, 14.5 mg·L^-1, respectively. The experimental results demonstrated that the BAF process is a suitable and highly efficient method to treat the wastewater.
基金supported by the National Natural Science Foundation of China(Grant Nos.51278381,51538009 and 51608380)the International Research Cooperation Project of Shanghai Science and Technology Committee(Grant No.15220721600)the Peak Discipline Construction on Civil Engineering of Shanghai Project
文摘Over the last decades,geo-structures are experiencing a rapid development in China.The potential risks inherent in the huge amount of construction and asset operation projects in China were well managed in the major project,i.e.the project of Shanghai Yangtze tunnel in 2002.Since then,risk assessment of geostructures has been gradually developed from a qualitative manner to a quantitative manner.However,the current practices of risk management have been paid considerable attention to the assessment,but little on risk control.As a result,the responses to risks occurrences after a comprehensive assessment are basically too late.In this paper,a smart system for risk sensing incorporating the wireless sensor network(WSN) on-site visualization techniques and the resilience-based repair strategy was proposed.The merit of this system is the real-time monitoring for geo-structural performance and dynamic pre-warning for safety of on-site workers.The sectional convergence,joint opening,and seepage of segmental lining of shield tunnel were monitored by the micro-electro-mechanical systems(MEMS) based sensors.The light emitting diode(LED) coupling with the above WSN system was used to indicate different risk levels on site.By sensing the risks and telling the risks in real time,the geo-risks could be controlled and the safety of geo-structures could be assured to a certain degree.Finally,a resilience-based analysis model was proposed for designing the repair strategy by using the measured data from the WSN system.The application and efficiency of this system have been validated by two cases including Shanghai metro tunnel and underwater road tunnel.
基金Supported by National Science and Technology Project of Water Pollution Control and Management(2008ZX07421-001)
文摘[Objective] The study aimed to discuss the application of a stereo constructed wetland to the treatment of slightly polluted source water. [Method] In this study, a new stereo constructed wetland mode was put forward, and a pilot project of water ecological purification in Xinsheng River, the diversion channel of Shijiuyang Waterwork in Jiaxing City, were analyzed. Afterwards, the impact factors of water purification by the technology were discussed from water quality and quantity, season and climate, species configuration, management and maintenance. [Result] Under three different hydraulic loading conditions, the pilot project effectively improved water SD and DO level, and reduced SS, CODCr, NH3-N, TN and TP significantly in summer and autumn, so that effluent water quality reached surface water standard at Grade III. [Conclusion] The stereo constructed wetland mode composed of constructed wetland and underwater forest used to treat slightly polluted source water is feasible and has a good promotion prospect.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB06060200)the National Natural Science Foundation of China (grants 41403050)
文摘A slightly acidic hot spring named "Female Tower"(t=73.5°C, pH=6.64) is located in the Jifei Geothermal Field, Yunnan Province, southwestern China. The precipitates in the hot spring are composed of large amounts of calcite, aragonite and sulfur. Scanning electron microscopy(SEM) analyses reveal that the microbial mats were formed from various coccoid or rod-shaped filamentous microbes. Transmission electron microscopy(TEM) shows that the intracellular sulfur granules are commonly associated with these microbes. A culture-independent molecular phylogenetic analysis demonstrates that the majority of the bacteria in the spring are sulfur-oxidizing bacteria. In the spring water, H2S concentration is up to 60 ppm, while SO4-(2-) concentration is only about 10 ppm. We speculate that H2S might derive from sulfur-oxidizing bacteria in this hot spring water, leading to the intracellular formation of sulfur granules. Meanwhile, this reaction increased the p H in the micronscale microdomains, which fosters the precipitation of calcium carbonate in the microbial mats. The results of this study indicate that the sulfur-oxidizing bacteria might play an important role in calcium carbonate precipitation in slightly acidic hot spring environments.
文摘In this study, a slightly curved Euler Bernoulli beam carrying a concentrated mass was handled. The beam was resting on an elastic foundation and simply supported at both ends. Effects of the concentrated mass on nonlin- ear vibrations were investigated. Sinusoidal and parabolic type functions were used as curvature functions. Equations of motion have cubic nonlinearities because of elongations during vibrations. Damping and harmonic excitation terms were added to the equations of motion. Method of mul- tiple scales, a perturbation technique, was used for solving integro-differential equation analytically. Natural frequen- cies were calculated exactly for different mass ratios, mass locations, curvature functions, and linear elastic foundation coefficients. Amplitude-phase modulation equations were found by considering primary resonance case. Effects of nonlinear terms on natural frequencies were calculated. Frequency-amplitude and frequency-response graphs were plotted. Finally effects of concentrated mass and chosen curvature function on nonlinear vibrations were investigated.
文摘Rich oxygen-biological activated carbon(RO-BAC)method developed from traditional BAC method is a sys-tem in which high pressure is applied to improve the oxy-gen concentration of the influent.Experiment withwastewater and the slightly deteriorated raw water showsthe system is an effective option for advanced treatmentof industry wastewater and pretreatment of slightly dete-riorated raw water.The experiment results and the in-fluential factors are discussed in this paper.