Investigation of unloading rock failure under differentσ_(2)facilitates the control mechanism of excavation surrounding rock.This study focused on single-sided unloading tests of granite specimens under true triaxial...Investigation of unloading rock failure under differentσ_(2)facilitates the control mechanism of excavation surrounding rock.This study focused on single-sided unloading tests of granite specimens under true triaxial conditions.The strength and failure characteristics were studied with micro-camera and acoustic emission(AE)monitoring.Furthermore,the choice of test path and the effect ofσ_(2)on fracture of unloading rock were discussed.Results show that the increasedσ_(2)can strengthen the stability of single-sided unloading rock.After unloading,the rock’s free surface underwent five phases,namely,inoculation,particle ejection,buckling rupture,stable failure,and unstable rockburst phases.Moreover,atσ_(2)≤30 MPa,the b value shows the following variation tendency:rising,dropping,significant fluctuation,and dropping,with dispersed damages signal.Atσ_(2)≥40 MPa,the tendency shows:a rise,a decrease,a slight fluctuation,and final drop,with concentrated damages signal.After unloading,AE energy is mainly concentrated in the micro-energy range.With the increasedσ_(2),the micro-energy ratio rises.In contrast,low,medium and large energy ratios drop gradually.The increased tensile fractures and decreased shear fractures indicate that the failure mode of the unloading rock gradually changes from tensile-shear mode to tensile-split one.The fractional dimension of the rock fragments first increases and then decreases with an inflection point at 20 MPa.The distribution of SIF on the planes changes asσ_(2)increases,resulting in strengthening and then weakening of the rock bearing capacity.展开更多
This paper investigates characteristics of ironless permanent magnet linear synchronous motor(PMLSM)based on Halbach array used for medium-speed(200km/h)maglev train.Long primary ironless coil is laid in the middle of...This paper investigates characteristics of ironless permanent magnet linear synchronous motor(PMLSM)based on Halbach array used for medium-speed(200km/h)maglev train.Long primary ironless coil is laid in the middle of track and the Halbach permanent magnet array is attached to the bottom of each bogie as a source of traction,U-shape electromagnets at the both sides of the train for levitation.Two dimensional analytical model of single-sided ironless PMLSM based on Halbach array is established,using linear overlay method,the no-load air gap magnetic field is calculated firstly,winding current density distribution is obtained for calculating the characteristics of thrust and normal force against power angle,including force characteristics with equal and unequal pole pitch,the influence of steel sleeper,etc.Besides,the mathematical model for this type motor is built by 3D finite element method,the traction characteristics of medium-speed maglev under maximum speed 200km/h are calculated.The characteristics of this type motor are satisfactory owing to there is no detent force in the motor and thrust force reach maximum meanwhile normal force can be eliminated.Calculation method is verified by comparing finite element results,experimental result on a 200kW type motor further validates the accuracy of calculation and some important conclusions are obtained.展开更多
An adaptive current compensation control for a single-sided linear induction motor(SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideratio...An adaptive current compensation control for a single-sided linear induction motor(SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideration of the specially dynamic eddy-effect(DEE) of the SLIM, a instantaneously tracing compensation of m-axis current component was analyzed. Second,adaptive current compensation based on Taylor-discretization algorithm was proposed. Third, an effective kind of nonlinear disturbance observer(NDOB) was employed to estimate and compensate the undesired load vibrations, then the robustness of the control system could be guaranteed. Experimental verification of the feasibility of the proposed method for an SLIM control system was performed, and it showed that the proposed adaptive compensation scheme with NDOB could significantly promote speed dynamical response and minimize speed ripple under the conditions of external load coupled vibrations and unavoidable feedback control variables measured errors, i.e., current and speed.展开更多
Based on the traditional measurement theory of transient plane source (TPS) technique, single-side TPS method is proposed for measuring the thermal conductivity of single specimen. The problem of transient heat conduc...Based on the traditional measurement theory of transient plane source (TPS) technique, single-side TPS method is proposed for measuring the thermal conductivity of single specimen. The problem of transient heat conduction in a semi-infinite boundary condition is studied and the theoretical formula of single-side TPS method is deduced. During the measurement, the influence of the probe heat capacity on the results is analyzed and the corresponding mathematical compensation model is established, and a series of experiments on different materials are conducted by hot disk probe at normal temperature and pressure. The results show that the relative error with the single-side TPS method is less than 5% and the relative standard deviation is no greater than 3%. This method has high accuracy and good reproducibility, which provides a feasible measuring method for single material that does not meet the requirements of the standard TPS theory.展开更多
The fiberglass reinforced plastic （FRP） pipelines have been used widely in oil-gas gathering and transportation. The defects of FRP pipelines would increase with the extension of service time. However, it is very di...The fiberglass reinforced plastic （FRP） pipelines have been used widely in oil-gas gathering and transportation. The defects of FRP pipelines would increase with the extension of service time. However, it is very difficult to detect the defects of FRP pipelines on-spot quickly. In this paper, a new method detecting defects for FRP pipes has been provided based on the NMR. The proton density distributions have been obtained at different depth of FRP components using single-side NMR. The experimental results show that there is a significant change of proton density distribution at the location of defects. And, these results would be useful for defects inspection of composite material component.展开更多
Purpose:To analyze the effect of right versus left long-term single-sided deafness(SSD)on sound source localization(SSL),discuss the necessity of intervention and treatment for SSD patients,and analyze the therapeutic...Purpose:To analyze the effect of right versus left long-term single-sided deafness(SSD)on sound source localization(SSL),discuss the necessity of intervention and treatment for SSD patients,and analyze the therapeutic effect of long-term unilateral cochlear implantation(UCI)from the perspective of SSL.Methods:This study included 25 patients with SSD,11 patients with UCI,and 30 participants with normal hearing(NH).Their SSL ability was tested by obtaining their average root mean square(RMS)error values of SSL test.Results:The results showed that the RMS error value of SSD,UCI and NH groups were 52.26±20.25◦,69.84±12.14◦and 4.27±2.66◦,respectively.The ability of SSL was better in the SSD-L group than that in the SSD-R group,and no significant difference existed in the SSD-R and the UCI group.Conclusion:When bilateral deafness patients select unilateral treatment,right-side cochlear implantation may be more beneficial in terms of SSL,which means that the central auditory cortex in long-term SSD patients is affected differently based on which side their deafness occurs.展开更多
No-till planters are very popular for maize seeding in fields covered with residue in annual wheat-maize double cropping system in North China Plain.However,there is no suitable depth control mechanism for existing no...No-till planters are very popular for maize seeding in fields covered with residue in annual wheat-maize double cropping system in North China Plain.However,there is no suitable depth control mechanism for existing no-till maize planters,and as a result,it is hard to obtain consistent planting depth,uniform emergence,and good passing ability at the same time.For the above reasons,a proper planting unit with a new type of depth-control mechanism was developed in this study.The mechanism consists of a single-side gauge wheel,a parallel four-bar linkage,a pair of double-disc opener,a V-shape press wheel and a depth regulator,which can adjust the planting depth from 30 mm to 90 mm to satisfy the agronomic requirement under different field conditions.Based on analysis and calculation,the width of gauge wheel was set to 50 mm while the length of parallel four-bar linkage was set to 350 mm.Field experiment was conducted and the results indicated that the newly designed planting unit with single-side gauge wheel performed well with regard to planting depth uniformity and anti-blocking ability.The planting depth uniformity and seed spacing quality were 95.45%and 91.90%,respectively,when the average height of stubble was 22.5 cm and residue amount was 0.64 kg/m^(2)in the field.It can satisfy the requirement of no-till maize planting on the cropland with residue and stubble in North China Plain.展开更多
The operation of symmetric double-sided and asymmetric single-sided vibro-impact nonlinear energy sinks(DSVI NES and SSVI NES)is considered in this study.The methodology of optimization procedures is described.It is e...The operation of symmetric double-sided and asymmetric single-sided vibro-impact nonlinear energy sinks(DSVI NES and SSVI NES)is considered in this study.The methodology of optimization procedures is described.It is emphasized that the execution of optimization procedures is ambiguous,allows for a great deal of arbitrariness,and requires experience and intuition on the part of the implementer.There are a lot of damper parameter sets providing similar attenuation of the primary structure(PS)vibrations.It is shown that the efficiency of such mitigation for both VI NES types with optimized parameters is similar.However,their dynamic behavior differs significantly.The system with the attached DSVI NES exhibits calm dynamics with periodic motion and symmetrical bilateral impacts on both obstacles.The system with attached SSVI NES exhibits rich complex dynamics when the exciting force frequency is varied.Periodic modes of different periodicity with different numbers of asymmetric impacts per cycle on the PS directly and on the obstacle alternate with various irregular regimes,namely,chaotic mode,intermittency,and crisis-induced intermittency.The regions of bilateral impacts are narrow and located near resonance;they are narrower for a system with an attached DSVI NES.In a system with an attached SSVI NES,there are wider areas of asymmetric unilateral impacts.展开更多
Nuclear magnetic resonance(NMR)measurements of water diffusion have been extensively used to probe microstructure in porous materials,such as biological tissue,however primarily using pulsed gradient spin echo(PGSE)me...Nuclear magnetic resonance(NMR)measurements of water diffusion have been extensively used to probe microstructure in porous materials,such as biological tissue,however primarily using pulsed gradient spin echo(PGSE)methods.Low-field single-sided NMR systems have built-in static gradients(SG)much stronger than typical PGSE maximum gradient strengths,which allows for the signal attenuation at extremely high b-values to be explored.Here,we perform SG spin echo(SGSE)and SG stimulated echo(SGSTE)diffusion measurements on biological cells,tissues,and gels.Measurements on fixed and live neonatal mouse spinal cord,lobster ventral nerve cord,and starved yeast cells all show multiexponential signal attenuation on a scale of b with significant signal fractions observed at b×Do>1 with b as high as 400 ms/um2.These persistent signal fractions trend with surface-to-volume ratios for these systems,as expected from porous media theory.An exception found for the case of fixed vs.live spinal cords was attributed to faster exchange or permeability in live spinal cords than in fixed spinal cords on the millisecond timescale.Data suggests the existence of multiple exchange processes in neural tissue,which may be relevant to the modeling of time-dependent diffusion in gray matter.The observed multi-exponential attenuation is from protons on water and not macromolecules because it remains proportional to the normalized signal when a specimen is washed with D20.The signal that persists to b×Do>1 is also drastically reduced after delipidation,indicating that it originates from lipid membranes that restrict water diffusion.The multiexponential or stretched exponential character of the signal attenuation at b×Do>1 appears mono-exponential when viewed on a scale of(b×Do)/3,suggesting it may originate from localization or motional averaging of water near membranes on sub-micron length scales.To try to disambiguate these two contributions,signal attenuation curves were compared at varying temperatures.While the curves align when normalizing them using the localization length scale,they separate on a motional averaging length scale.This supports localization as the source of non-Gaussian displacements,but this interpretation is still provisional due to the possible confounds of heterogeneity,exchange,and relaxation.Measurements on two types of gel phantoms designed to mimic extracellular matrix.one with charged functional groups synthesized from polyacrylic acid(PAC)and another with uncharged functional groups synthesized from polyacrylamide(PAM),both exhibit signal at b×Do>1,potentially due to water interacting with macromolecules.These preliminary finding motivate future research into contrast and attenuation mechanisms in tissue with low-field,high-gradient NMR。展开更多
Two schemes of quantum secret sharing are proposed via single electron spin confined in charged QDs inside a single-sided microcavity and a double-sided microcavity, respectively. Both schemes rely on coherent photons...Two schemes of quantum secret sharing are proposed via single electron spin confined in charged QDs inside a single-sided microcavity and a double-sided microcavity, respectively. Both schemes rely on coherent photonspin interaction. The two schemes axe both deterministic and can be extended to multipartite secret sharing.展开更多
Pumping ventilation(PV),a special single-sided ventilation(SSV),has been certified as an effective strategy to improve the air exchange rate of SSV.However,most studies targeted on the single space,and few studies hav...Pumping ventilation(PV),a special single-sided ventilation(SSV),has been certified as an effective strategy to improve the air exchange rate of SSV.However,most studies targeted on the single space,and few studies have been focused on the effect of internal partitioning on PV.This paper aims to evaluate the ventilation performance of PV influenced by different configurations of internal partitioning.Computational fluid dynamics(CFD)simulation was used to predict the flow fields and ventilation rates.The width(w/H),height(h/H)and location(d/H)are the three main internal partition parameters considered in this study.The simulation results showed that the total,mean and fluctuating ventilation rates all decrease with wider internal partitions.The normalized total ventilation rate decreases by 7.6%when w/H is increased from 50%to 75%.However,the reduction rate is only 0.23%between w/H=0 and 25%,and only 0.61%between w/H=25%and 50%.The ventilation rate is hardly reduced by increasing the partition width when w/H<50%,whereas greatly reduced by wider partition for w/H>50%.Increasing the partition height will reduce the mean ventilation rate but promote the fluctuating and total ventilation rate in some cases.An increase of total ventilation rate by 1.4%is observed from h/H=50%to 75%.The ventilation rate is larger when the internal partition is attached to the leeward or windward wall.The total,mean and fluctuating ventilation rates for d/H=50%are relatively higher than d/H=0 by 1.5%,3.1%and 0.8%,respectively.Hence the internal partition should be mounted attached to the windward wall so as to obtain the greatest pumping ventilation rate.The periodicity of pumping flow oscillation and pumping frequency are independent of the partition configurations.The peak power of pumping flow is the lowest for the widest internal partition and is negatively affected by the partition height,but it generally has a positive correlation with the distance between the partition and leeward wall.Present research will help to understand pumping ventilation mechanism in real buildings with internal partitioning and provide theoretical basis for developing unsteady natural ventilation technology in low-carbon buildings.展开更多
基金This work was supported by the Scientific Research Project of Anhui Province Universities,China(No.YJS20210388)the National Natural Science Foundation of China(Nos.51974009,52004006,and 52004005)+2 种基金the Major Science and Technology Special Project of Anhui Province,China(No.202203a07020011)the Collaborative Innovation Project of Anhui Province Universities,China(No.GXXT-2021-075)the Huaibei City Science and Technology Major Program(No.Z2020005).
文摘Investigation of unloading rock failure under differentσ_(2)facilitates the control mechanism of excavation surrounding rock.This study focused on single-sided unloading tests of granite specimens under true triaxial conditions.The strength and failure characteristics were studied with micro-camera and acoustic emission(AE)monitoring.Furthermore,the choice of test path and the effect ofσ_(2)on fracture of unloading rock were discussed.Results show that the increasedσ_(2)can strengthen the stability of single-sided unloading rock.After unloading,the rock’s free surface underwent five phases,namely,inoculation,particle ejection,buckling rupture,stable failure,and unstable rockburst phases.Moreover,atσ_(2)≤30 MPa,the b value shows the following variation tendency:rising,dropping,significant fluctuation,and dropping,with dispersed damages signal.Atσ_(2)≥40 MPa,the tendency shows:a rise,a decrease,a slight fluctuation,and final drop,with concentrated damages signal.After unloading,AE energy is mainly concentrated in the micro-energy range.With the increasedσ_(2),the micro-energy ratio rises.In contrast,low,medium and large energy ratios drop gradually.The increased tensile fractures and decreased shear fractures indicate that the failure mode of the unloading rock gradually changes from tensile-shear mode to tensile-split one.The fractional dimension of the rock fragments first increases and then decreases with an inflection point at 20 MPa.The distribution of SIF on the planes changes asσ_(2)increases,resulting in strengthening and then weakening of the rock bearing capacity.
基金This work was supported in part by the National Key R&D Program of China under Grant 2017YFB1201003.
文摘This paper investigates characteristics of ironless permanent magnet linear synchronous motor(PMLSM)based on Halbach array used for medium-speed(200km/h)maglev train.Long primary ironless coil is laid in the middle of track and the Halbach permanent magnet array is attached to the bottom of each bogie as a source of traction,U-shape electromagnets at the both sides of the train for levitation.Two dimensional analytical model of single-sided ironless PMLSM based on Halbach array is established,using linear overlay method,the no-load air gap magnetic field is calculated firstly,winding current density distribution is obtained for calculating the characteristics of thrust and normal force against power angle,including force characteristics with equal and unequal pole pitch,the influence of steel sleeper,etc.Besides,the mathematical model for this type motor is built by 3D finite element method,the traction characteristics of medium-speed maglev under maximum speed 200km/h are calculated.The characteristics of this type motor are satisfactory owing to there is no detent force in the motor and thrust force reach maximum meanwhile normal force can be eliminated.Calculation method is verified by comparing finite element results,experimental result on a 200kW type motor further validates the accuracy of calculation and some important conclusions are obtained.
基金Project(114601034)supported by the Scholarship Award for Excellent Doctoral Students Granted by the Ministry of Education of ChinaProject(61273158)supported by the National Natural Science Foundation of China
文摘An adaptive current compensation control for a single-sided linear induction motor(SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideration of the specially dynamic eddy-effect(DEE) of the SLIM, a instantaneously tracing compensation of m-axis current component was analyzed. Second,adaptive current compensation based on Taylor-discretization algorithm was proposed. Third, an effective kind of nonlinear disturbance observer(NDOB) was employed to estimate and compensate the undesired load vibrations, then the robustness of the control system could be guaranteed. Experimental verification of the feasibility of the proposed method for an SLIM control system was performed, and it showed that the proposed adaptive compensation scheme with NDOB could significantly promote speed dynamical response and minimize speed ripple under the conditions of external load coupled vibrations and unavoidable feedback control variables measured errors, i.e., current and speed.
文摘Based on the traditional measurement theory of transient plane source (TPS) technique, single-side TPS method is proposed for measuring the thermal conductivity of single specimen. The problem of transient heat conduction in a semi-infinite boundary condition is studied and the theoretical formula of single-side TPS method is deduced. During the measurement, the influence of the probe heat capacity on the results is analyzed and the corresponding mathematical compensation model is established, and a series of experiments on different materials are conducted by hot disk probe at normal temperature and pressure. The results show that the relative error with the single-side TPS method is less than 5% and the relative standard deviation is no greater than 3%. This method has high accuracy and good reproducibility, which provides a feasible measuring method for single material that does not meet the requirements of the standard TPS theory.
文摘The fiberglass reinforced plastic （FRP） pipelines have been used widely in oil-gas gathering and transportation. The defects of FRP pipelines would increase with the extension of service time. However, it is very difficult to detect the defects of FRP pipelines on-spot quickly. In this paper, a new method detecting defects for FRP pipes has been provided based on the NMR. The proton density distributions have been obtained at different depth of FRP components using single-side NMR. The experimental results show that there is a significant change of proton density distribution at the location of defects. And, these results would be useful for defects inspection of composite material component.
基金supported by the National Key Research and Development Project of China(2020YFC20052003 to S.M.Yang)Key International(Regional)Joint Research Program of National Natural Science Foundation of China(NSFC#81820108009 to S.M.Yang)National Natural Science Foundation of China(NSFC#82000976 to J.N.Li).
文摘Purpose:To analyze the effect of right versus left long-term single-sided deafness(SSD)on sound source localization(SSL),discuss the necessity of intervention and treatment for SSD patients,and analyze the therapeutic effect of long-term unilateral cochlear implantation(UCI)from the perspective of SSL.Methods:This study included 25 patients with SSD,11 patients with UCI,and 30 participants with normal hearing(NH).Their SSL ability was tested by obtaining their average root mean square(RMS)error values of SSL test.Results:The results showed that the RMS error value of SSD,UCI and NH groups were 52.26±20.25◦,69.84±12.14◦and 4.27±2.66◦,respectively.The ability of SSL was better in the SSD-L group than that in the SSD-R group,and no significant difference existed in the SSD-R and the UCI group.Conclusion:When bilateral deafness patients select unilateral treatment,right-side cochlear implantation may be more beneficial in terms of SSL,which means that the central auditory cortex in long-term SSD patients is affected differently based on which side their deafness occurs.
基金the supports of Special Fund for Agro-scientific Research in the Public Interest(201503117)National Industry System of Corn Technology(CARS-02)。
文摘No-till planters are very popular for maize seeding in fields covered with residue in annual wheat-maize double cropping system in North China Plain.However,there is no suitable depth control mechanism for existing no-till maize planters,and as a result,it is hard to obtain consistent planting depth,uniform emergence,and good passing ability at the same time.For the above reasons,a proper planting unit with a new type of depth-control mechanism was developed in this study.The mechanism consists of a single-side gauge wheel,a parallel four-bar linkage,a pair of double-disc opener,a V-shape press wheel and a depth regulator,which can adjust the planting depth from 30 mm to 90 mm to satisfy the agronomic requirement under different field conditions.Based on analysis and calculation,the width of gauge wheel was set to 50 mm while the length of parallel four-bar linkage was set to 350 mm.Field experiment was conducted and the results indicated that the newly designed planting unit with single-side gauge wheel performed well with regard to planting depth uniformity and anti-blocking ability.The planting depth uniformity and seed spacing quality were 95.45%and 91.90%,respectively,when the average height of stubble was 22.5 cm and residue amount was 0.64 kg/m^(2)in the field.It can satisfy the requirement of no-till maize planting on the cropland with residue and stubble in North China Plain.
文摘The operation of symmetric double-sided and asymmetric single-sided vibro-impact nonlinear energy sinks(DSVI NES and SSVI NES)is considered in this study.The methodology of optimization procedures is described.It is emphasized that the execution of optimization procedures is ambiguous,allows for a great deal of arbitrariness,and requires experience and intuition on the part of the implementer.There are a lot of damper parameter sets providing similar attenuation of the primary structure(PS)vibrations.It is shown that the efficiency of such mitigation for both VI NES types with optimized parameters is similar.However,their dynamic behavior differs significantly.The system with the attached DSVI NES exhibits calm dynamics with periodic motion and symmetrical bilateral impacts on both obstacles.The system with attached SSVI NES exhibits rich complex dynamics when the exciting force frequency is varied.Periodic modes of different periodicity with different numbers of asymmetric impacts per cycle on the PS directly and on the obstacle alternate with various irregular regimes,namely,chaotic mode,intermittency,and crisis-induced intermittency.The regions of bilateral impacts are narrow and located near resonance;they are narrower for a system with an attached DSVI NES.In a system with an attached SSVI NES,there are wider areas of asymmetric unilateral impacts.
基金supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.VJW acknowledges additional supported by NIGMS grant(K99 GM140338-01)for this work.
文摘Nuclear magnetic resonance(NMR)measurements of water diffusion have been extensively used to probe microstructure in porous materials,such as biological tissue,however primarily using pulsed gradient spin echo(PGSE)methods.Low-field single-sided NMR systems have built-in static gradients(SG)much stronger than typical PGSE maximum gradient strengths,which allows for the signal attenuation at extremely high b-values to be explored.Here,we perform SG spin echo(SGSE)and SG stimulated echo(SGSTE)diffusion measurements on biological cells,tissues,and gels.Measurements on fixed and live neonatal mouse spinal cord,lobster ventral nerve cord,and starved yeast cells all show multiexponential signal attenuation on a scale of b with significant signal fractions observed at b×Do>1 with b as high as 400 ms/um2.These persistent signal fractions trend with surface-to-volume ratios for these systems,as expected from porous media theory.An exception found for the case of fixed vs.live spinal cords was attributed to faster exchange or permeability in live spinal cords than in fixed spinal cords on the millisecond timescale.Data suggests the existence of multiple exchange processes in neural tissue,which may be relevant to the modeling of time-dependent diffusion in gray matter.The observed multi-exponential attenuation is from protons on water and not macromolecules because it remains proportional to the normalized signal when a specimen is washed with D20.The signal that persists to b×Do>1 is also drastically reduced after delipidation,indicating that it originates from lipid membranes that restrict water diffusion.The multiexponential or stretched exponential character of the signal attenuation at b×Do>1 appears mono-exponential when viewed on a scale of(b×Do)/3,suggesting it may originate from localization or motional averaging of water near membranes on sub-micron length scales.To try to disambiguate these two contributions,signal attenuation curves were compared at varying temperatures.While the curves align when normalizing them using the localization length scale,they separate on a motional averaging length scale.This supports localization as the source of non-Gaussian displacements,but this interpretation is still provisional due to the possible confounds of heterogeneity,exchange,and relaxation.Measurements on two types of gel phantoms designed to mimic extracellular matrix.one with charged functional groups synthesized from polyacrylic acid(PAC)and another with uncharged functional groups synthesized from polyacrylamide(PAM),both exhibit signal at b×Do>1,potentially due to water interacting with macromolecules.These preliminary finding motivate future research into contrast and attenuation mechanisms in tissue with low-field,high-gradient NMR。
文摘Two schemes of quantum secret sharing are proposed via single electron spin confined in charged QDs inside a single-sided microcavity and a double-sided microcavity, respectively. Both schemes rely on coherent photonspin interaction. The two schemes axe both deterministic and can be extended to multipartite secret sharing.
基金Authors would gratefully acknowledge the financial supports of the Natural Science Foundation of the Anhui Higher Education Institutions of China(2022AH050307)the Opening Fund of State Key Laboratory of Green Building in Western China(LSKF202312)+3 种基金the National Key Research and Development Program of the Ministry of Science and Technology of China(No.2022YFC3801601-02,Wuhan University)the Science Foundation(Meteorology)Innovation Development Joint Fund Key Project of Hubei Province(No.2023M15,Wuhan University)the Foreign Aid Project for High-Level Cooperation and Exchange Activities of the Ministry of Science and Technology(No.202213,Wuhan University)the Natural Science Foundation of China(No.51778504,No.U1867221,Wuhan University).
文摘Pumping ventilation(PV),a special single-sided ventilation(SSV),has been certified as an effective strategy to improve the air exchange rate of SSV.However,most studies targeted on the single space,and few studies have been focused on the effect of internal partitioning on PV.This paper aims to evaluate the ventilation performance of PV influenced by different configurations of internal partitioning.Computational fluid dynamics(CFD)simulation was used to predict the flow fields and ventilation rates.The width(w/H),height(h/H)and location(d/H)are the three main internal partition parameters considered in this study.The simulation results showed that the total,mean and fluctuating ventilation rates all decrease with wider internal partitions.The normalized total ventilation rate decreases by 7.6%when w/H is increased from 50%to 75%.However,the reduction rate is only 0.23%between w/H=0 and 25%,and only 0.61%between w/H=25%and 50%.The ventilation rate is hardly reduced by increasing the partition width when w/H<50%,whereas greatly reduced by wider partition for w/H>50%.Increasing the partition height will reduce the mean ventilation rate but promote the fluctuating and total ventilation rate in some cases.An increase of total ventilation rate by 1.4%is observed from h/H=50%to 75%.The ventilation rate is larger when the internal partition is attached to the leeward or windward wall.The total,mean and fluctuating ventilation rates for d/H=50%are relatively higher than d/H=0 by 1.5%,3.1%and 0.8%,respectively.Hence the internal partition should be mounted attached to the windward wall so as to obtain the greatest pumping ventilation rate.The periodicity of pumping flow oscillation and pumping frequency are independent of the partition configurations.The peak power of pumping flow is the lowest for the widest internal partition and is negatively affected by the partition height,but it generally has a positive correlation with the distance between the partition and leeward wall.Present research will help to understand pumping ventilation mechanism in real buildings with internal partitioning and provide theoretical basis for developing unsteady natural ventilation technology in low-carbon buildings.
