Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and...Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and time-lapse seismic surveillance of both conventional and unconventional reservoir and overburden performances.A Seismic Elastic Moduli Module has been developed,based on the forced-oscillations method,to experimentally investigate the frequency dependence of Young's modulus and Poisson's ratio,as well as the inferred attenuation,of cylindrical samples under different confining pressure conditions.Calibration with three standard samples showed that the measured elastic moduli were consistent with the published data,indicating that the new apparatus can operate reliably over a wide frequency range of f∈[1-2000,10^(6)]Hz.The Young's modulus and Poisson's ratio of the shale and the tight sandstone samples were measured under axial stress oscillations to assess the frequency-and pressure-dependent effects.Under dry condition,both samples appear to be nearly frequency independent,with weak pressure dependence for the shale and significant pressure dependence for the sandstone.In particular,it was found that the tight sandstone with complex pore microstructure exhibited apparent dispersion and attenuation under brine or glycerin saturation conditions,the levels of which were strongly influenced by the increased effective pressure.In addition,the measured Young's moduli results were compared with the theoretical predictions from a scaled poroelastic model with a reasonably good agreement,revealing that the combined fluid flow mechanisms at both mesoscopic and microscopic scales possibly responsible for the measured dispersion.展开更多
In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measuremen...In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.展开更多
We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is know...We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is known to Alice while the two-qubit state which is a non-maximally entangled Bell state is known to Candy. The three parties are connected through a single entangled state which acts as a quantum channel. We first describe the protocol in the ideal case when the entangled channel under use is in a pure state. After that, we consider the effect of amplitude damping(AD) noise on the quantum channel and describe the protocol executed through the noisy channel. The decrement of the fidelity is shown to occur with the increment in the noise parameter. This is shown by numerical computation in specific examples of the states to be created. Finally, we show that it is possible to maintain the label of fidelity to some extent and hence to decrease the effect of noise by the application of weak and reversal measurements. We also present a scheme for the generation of the five-qubit entangled resource which we require as a quantum channel. The generation scheme is run on the IBMQ platform.展开更多
Visible light communication(VLC)has attracted much attention in the research of sixthgeneration(6G)systems.Furthermore,channel modeling is the foundation for designing efficient and robust VLC systems.In this paper,we...Visible light communication(VLC)has attracted much attention in the research of sixthgeneration(6G)systems.Furthermore,channel modeling is the foundation for designing efficient and robust VLC systems.In this paper,we present extensive VLC channel measurement campaigns in indoor environments,i.e.,an office and a corridor.Based on the measured data,the large-scale fading characteristics and multipath-related characteristics,including omnidirectional optical path loss(OPL),K-factor,power angular spectrum(PAS),angle spread(AS),and clustering characteristics,are analyzed and modeled through a statistical method.Based on the extracted statistics of the above-mentioned channel characteristics,we propose a statistical spatial channel model(SSCM)capable of modeling multipath in the spatial domain.Furthermore,the simulated statistics of the proposed model are compared with the measured statistics.For instance,in the office,the simulated path loss exponent(PLE)and the measured PLE are 1.96and 1.97,respectively.And,the simulated medians of AS and measured medians of AS are 25.94°and 24.84°,respectively.Generally,the fact that the simulated results fit well with measured results has demonstrated the accuracy of our SSCM.展开更多
This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and position...This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.展开更多
Excavation with tunnel boring machine(TBM)can generate vibrations,causing damages to neighbouring buildings and disturbing the residents or the equipment.This problem is particularly challenging in urban areas,where T...Excavation with tunnel boring machine(TBM)can generate vibrations,causing damages to neighbouring buildings and disturbing the residents or the equipment.This problem is particularly challenging in urban areas,where TBMs are increasingly large in diameter and shallow in depth.In response to this problem,four experimental campaigns were carried out in different geotechnical contexts in France.The vibration measurements were acquired on the surface and inside the TBMs.These measurements are also complemented by few data in the literature.An original methodology of signal processing is pro-posed to characterize the amplitude of the particle velocities,as well as the frequency content of the signals to highlight the most energetic bands.The levels of vibrations are also compared with the thresholds existing in various European regulations concerning the impact on neighbouring structures and the disturbance to local residents.展开更多
In dielectrometry,traditional analytical and numerical algorithms are difficultly employed in complex resonant cavities.For a special kind of structure(a rotating resonant cavity),the body of revolution finite-element...In dielectrometry,traditional analytical and numerical algorithms are difficultly employed in complex resonant cavities.For a special kind of structure(a rotating resonant cavity),the body of revolution finite-element method(BOR-FEM)is employed to calculate the resonant parameters and dielectric parameters.In this paper,several typical resonant structures are selected for analysis and verification.Compared with the resonance parameter values in the literature and the simulation results of commercial software,the error of the BOR-FEM calculation is less than 0.9%and a single solution time is less than 1 s.Reentrant coaxial resonant cavities loaded with dielectric materials are analyzed using this method and compared with simulation results,showing good agreement.Finally,in this paper,the established BOR-FEM method is successfully applied with a machined cavity for the accurate measurement of the complex dielectric constant of dielectric materials.The test specimens were machined from polytetrafluoroethylene,fused silica and Al_(2)O_(3),and the test results showed good agreement with the literature reference values.展开更多
Optical and visual measurement technology is used widely in fields that involve geometric measurements,and among such technology are laser and vision-based displacement measuring modules(LVDMMs).The displacement trans...Optical and visual measurement technology is used widely in fields that involve geometric measurements,and among such technology are laser and vision-based displacement measuring modules(LVDMMs).The displacement transformation coefficient(DTC)of an LVDMM changes with the coordinates in the camera image coordinate system during the displacement measuring process,and these changes affect the displacement measurement accuracy of LVDMMs in the full field of view(FFOV).To give LVDMMs higher accuracy in the FFOV and make them adaptable to widely varying measurement demands,a new calibration method is proposed to improve the displacement measurement accuracy of LVDMMs in the FFOV.First,an image coordinate system,a pixel measurement coordinate system,and a displacement measurement coordinate system are established on the laser receiving screen of the LVDMM.In addition,marker spots in the FFOV are selected,and the DTCs at the marker spots are obtained from calibration experiments.Also,a fitting method based on locally weighted scatterplot smoothing(LOWESS)is selected,and with this fitting method the distribution functions of the DTCs in the FFOV are obtained based on the DTCs at the marker spots.Finally,the calibrated distribution functions of the DTCs are applied to the LVDMM,and experiments conducted to verify the displacement measurement accuracies are reported.The results show that the FFOV measurement accuracies for horizontal and vertical displacements are better than±15μm and±19μm,respectively,and that for oblique displacement is better than±24μm.Compared with the traditional calibration method,the displacement measurement error in the FFOV is now 90%smaller.This research on an improved calibration method has certain significance for improving the measurement accuracy of LVDMMs in the FFOV,and it provides a new method and idea for other vision-based fields in which camera parameters must be calibrated.展开更多
A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider ...A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider (BEPCII). However, the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past. With a reliable kicker structure, a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII. A comparison of the numerical simulation was conducted for three kicker models, demonstrating the comprehensive advantage of the three-metal-strip kicker. Furthermore, impedance bench measurements were conducted on a prototype of a three-metal-strip kicker. The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method. A satisfactory agreement was obtained between the numerical simulations and measurements. Based on the numerical simulation data, the loss factor was 0.01721 V/pC, and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4%of the parasitic loss of the beam was deposited on the metal strips, and the total heat deposition power on the kicker was between 113.3 and 131.5 W. The obtained heat deposition powers can be considered as a reference for establishing the cooling system.展开更多
A novel method to measure the flow rate in a wet gas is presented.Due to the presence of liquid,there is a deviation in the measurement of the gas volume flow rate obtained with standard vortex flow-meters.The propose...A novel method to measure the flow rate in a wet gas is presented.Due to the presence of liquid,there is a deviation in the measurement of the gas volume flow rate obtained with standard vortex flow-meters.The proposed method is based on a correction factor determined through the application of an over-reading approach to a bluff body in mist flow.The correction factor is obtained from the slip velocity ratio,i.e.,the ratio of droplet velocity to gas velocity,based on the analysis of the fluid velocity distribution in the pipeline section.It also takes into account relevant theoretical arguments.It is shown that the predicted results fit the experimental results well.展开更多
State departments of transportation’s (DOTs) decisions to invest resources to expand or implement intelligent transportation systems (ITS) programs or even retire existing infrastructure need to be based on performan...State departments of transportation’s (DOTs) decisions to invest resources to expand or implement intelligent transportation systems (ITS) programs or even retire existing infrastructure need to be based on performance evaluations. Nonetheless, an apparent gap exists between the need for ITS performance measurements and the actual implementation. The evidence available points to challenges in the ITS performance measurement processes. This paper evaluated the state of practice of performance measurement for ITS across the US and provided insights. A comprehensive literature review assessed the use of performance measures by DOTs for monitoring implemented ITS programs. Based on the gaps identified through the literature review, a nationwide qualitative survey was used to gather insights from key stakeholders on the subject matter and presented in this paper. From the data gathered, performance measurement of ITS is fairly integrated into ITS programs by DOTs, with most agencies considering the process beneficial. There, however, exist reasons that prevent agencies from measuring ITS performance to greater detail and quality. These include lack of data, fragmented or incomparable data formats, the complexity of the endeavor, lack of data scientists, and difficulty assigning responsibilities when inter-agency collaboration is required. Additionally, DOTs do not benchmark or compare their ITS performance with others for reasons that include lack of data, lack of guidance or best practices, and incomparable data formats. This paper is relevant as it provides insights expected to guide DOTs and other agencies in developing or reevaluating their ITS performance measurement processes.展开更多
Introduction: The elements and perception of beauty vary between populations around the world. To obtain better results, surgical techniques should be planned based on anthropometric characteristics of the race, locat...Introduction: The elements and perception of beauty vary between populations around the world. To obtain better results, surgical techniques should be planned based on anthropometric characteristics of the race, location, and body mass index (BMI). Objectives: To determine which are the standard measurements and anatomical proportions of the breast in a healthy Mexican women population. Materials and Methods: Female Mexican volunteers between 20 and 60 years of age, without any history of breast illness or breast surgery were studied. Demographic information and standard breast anthropometric measurements were collected manually by one of the authors. For the statistical analysis a Student-T test was performed, and the Pearson correlation coefficient was obtained using the latest version of SPSS software. Results: 78 volunteers were included in the analysis. Mean height, weight and BMI were 1.6 m, 68.9 Kg, and 26.6 Kg/m2 respectively. The mean anthropometric values found were: Supra Sternal notch to nipple distance (SSN:N) 22 cm, Breast volume (BV) 372.6 cm3, Upper breast pole length (UBPL) 11 cm, Lower Breast Pole length (LBPL) 7.7 cm, Midline to Nipple distance (ML:N) 10.2 cm, Transverse diameter of the Nipple areola complex (NAC-T) 4.1 cm, Height of the Nipple Areola Complex (NAC-H) 4.1 cm, Base of the breast (BB) 13.4 cm, Upper Pole to Lower Pole Ratio (UPP:LPP) 58.9:41.1. A statistically significant difference between Right and left breast was not found. The UPP/ LPP ratio in our population is far different from what is considered internationally aesthetic (45:55). A positive correlation was found between weight/ BMI and SSN:N, BV, BB, ML:N and LBPL. Also between age and SSN:N, LBPL, BV and BB. Conclusion: This study sets the Anthropometric grounds in Mexican population for an objective individual patient analysis and comparison with the female population of this and other nations.展开更多
As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. Thi...As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.展开更多
NOAA AVHRR data from the Bay of Biscay between 1988 and 1990 have been examined in order to extract information on the fluctuations of sea surface temperature (SST) at the diurnal time scale. The temporal and spatial ...NOAA AVHRR data from the Bay of Biscay between 1988 and 1990 have been examined in order to extract information on the fluctuations of sea surface temperature (SST) at the diurnal time scale. The temporal and spatial distributions of diurnal warming in the area are obtained. The diurnal warming occurs during the summer months. Large diurnal warming in excess of 1℃ is found within 100 km along the west coast of France and within 30 km along the north coast of Spain. In the central Bay of Biscay the diurnal warming is typically about 0.5℃. The diurnal warming up to 6℃ is observed occasionally in the coastal areas where the wind speed is very low. A one-dimensional oceanic mixed-layer model has been used to simulate the diurnal warming. The results demonstrate that the diurnal warming increases with the decrease of the wind speed and the increase of the net heat flux. The comparison shows that the model results are in good agreement with the satellite measurements.展开更多
We present systematic investigations on the physics,detection performance and inversion of logging-while-drilling extradeep azimuthal resistivity measurements(EDARM).First,the definitions of EDRAM measurements are dis...We present systematic investigations on the physics,detection performance and inversion of logging-while-drilling extradeep azimuthal resistivity measurements(EDARM).First,the definitions of EDRAM measurements are discussed,followed by the derivation of the attenuation and phase-shift geometrical factors to illustrate the relative contributions of formation units to the observed signals.Then,a new definition of detection depth,which considers the uncertainty of inversion results caused by the data noise,is proposed to quantify the detection capability of ED ARM.Finally,the B ayesian theory associated with Markov chain Monte Carlo sampling is introduced for fast processing of EDARM data.Numerical results show that ED ARM is capable of detecting the azimuth and distance of remote bed boundaries,and the detection capability increases with increasing spacing and resistivity contrast.The EDARM tool can accommodate a large range of formation resistivity and is able to provide the resistivity anisotropy at arbitrary relative dipping angles.In addition,multiple bed boundaries and reservoir images near the borehole are readily obtained by using the Bayesian inversion.展开更多
A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-ge...A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.展开更多
The presence of embedded convection in stratiform clouds strongly affects ice microphysical properties and precipitation formation.In situ aircraft measurements,including upward and downward spirals and horizontal pen...The presence of embedded convection in stratiform clouds strongly affects ice microphysical properties and precipitation formation.In situ aircraft measurements,including upward and downward spirals and horizontal penetrations,were performed within both embedded convective cells and stratiform regions of a mixedphase stratiform cloud system on 22 May 2017.Supercooled liquid water measurements,particle size distributions,and particle habits in different cloud regions were discussed with the intent of characterizing the riming process and determining how particle size distributions vary from convective to stratiform regions.Significant amounts of supercooled liquid water,with maxima up to 0.6 g m−3,were observed between−3℃ and−6℃ in the embedded convective cells while the peak liquid water content was generally less than 0.1 g m−3 in the stratiform regions.There are two distinct differences in particle size distributions between convective and stratiform regions.One difference is the significant shift toward larger particles from upper−15℃ to lower−10℃ in the convective region,with the maximum particle dimensions increasing from less than 6000μm to over 1 cm.The particles larger than 1 cm at−10℃ are composed of dendrites and their aggregates.The other difference is the large concentrations of small particles(25–205μm)at temperatures between−3℃ and−5℃ in the convective region,where rimed ice particles and needles coexist.Needle regions are observed from three of the five spirals,but only the cloud conditions within the convective region fit into the Hallett-Mossop criteria.展开更多
The terrestrial time-variable gravity measurements are characterized by a high signal-to-noise ratio and sensitivity to the sources of mass change in the Earth's crust.These gravity data have many applications,suc...The terrestrial time-variable gravity measurements are characterized by a high signal-to-noise ratio and sensitivity to the sources of mass change in the Earth's crust.These gravity data have many applications,such as surface deformation,groundwater storage changes,and mass migration before and after earthquakes.Based on repeated terrestrial gravity measurements at 198 gravity stations in the Sichuan-Yunnan region(SYR)from 2015 to 2017,we determine a time series of degree 120 gravity fields using the localized spherical harmonic(Slepian)basis functions.Our results show that adopting the first 6 Slepian basis functions is sufficient for effective localized Slepian modeling in the SYR.The differences between two gravity campaigns at the same time of year show an obvious correlation with tectonic features.The degree 120 timevariable gravity models presented in this paper will benefit the study of the regional mass migration inside the crust of the SYR and supplement the existing geophysical models for the China Seismic Experimental Site.展开更多
A Kelvin probe was used as reference in this study on electrochemical measurements of a simulatedmarine atmospheric corrosion system (electrode covered by a very thin electrolyte layer). The experimentalsetups for imp...A Kelvin probe was used as reference in this study on electrochemical measurements of a simulatedmarine atmospheric corrosion system (electrode covered by a very thin electrolyte layer). The experimentalsetups for improved measurements proved satisfactory for the conventional steady-state electrochemicalmeasurements in atmospheric studies.展开更多
基金The authors would like to acknowledge financial support from NSFC Basic Research Program on Deep Petroleum Resource Accumulation and Key Engineering Technologies(U19B6003-04-03)National Natural Science Foundation of China(41930425)+2 种基金Beijing Natural Science Foundation(8222073),R&D Department of China National Petroleum Corporation(Investigations on fundamental experiments and advanced theoretical methods in geophysical prospecting applications,2022DQ0604-01)Scientific Research and Technology Development Project of PetroChina(2021DJ1206)National Key Research and Development Program of China(2018YFA0702504).
文摘Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and time-lapse seismic surveillance of both conventional and unconventional reservoir and overburden performances.A Seismic Elastic Moduli Module has been developed,based on the forced-oscillations method,to experimentally investigate the frequency dependence of Young's modulus and Poisson's ratio,as well as the inferred attenuation,of cylindrical samples under different confining pressure conditions.Calibration with three standard samples showed that the measured elastic moduli were consistent with the published data,indicating that the new apparatus can operate reliably over a wide frequency range of f∈[1-2000,10^(6)]Hz.The Young's modulus and Poisson's ratio of the shale and the tight sandstone samples were measured under axial stress oscillations to assess the frequency-and pressure-dependent effects.Under dry condition,both samples appear to be nearly frequency independent,with weak pressure dependence for the shale and significant pressure dependence for the sandstone.In particular,it was found that the tight sandstone with complex pore microstructure exhibited apparent dispersion and attenuation under brine or glycerin saturation conditions,the levels of which were strongly influenced by the increased effective pressure.In addition,the measured Young's moduli results were compared with the theoretical predictions from a scaled poroelastic model with a reasonably good agreement,revealing that the combined fluid flow mechanisms at both mesoscopic and microscopic scales possibly responsible for the measured dispersion.
文摘In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.
基金Project supported by Indian Institute of Engineering Science and Technology, Shibpur, India
文摘We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is known to Alice while the two-qubit state which is a non-maximally entangled Bell state is known to Candy. The three parties are connected through a single entangled state which acts as a quantum channel. We first describe the protocol in the ideal case when the entangled channel under use is in a pure state. After that, we consider the effect of amplitude damping(AD) noise on the quantum channel and describe the protocol executed through the noisy channel. The decrement of the fidelity is shown to occur with the increment in the noise parameter. This is shown by numerical computation in specific examples of the states to be created. Finally, we show that it is possible to maintain the label of fidelity to some extent and hence to decrease the effect of noise by the application of weak and reversal measurements. We also present a scheme for the generation of the five-qubit entangled resource which we require as a quantum channel. The generation scheme is run on the IBMQ platform.
基金supported by the National Science Fund for Distinguished Young Scholars(No.61925102)the National Natural Science Foundation of China(No.62201086,92167202,62201087,62101069)BUPT-CMCC Joint Innovation Center,and State Key Laboratory of IPOC(BUPT)(No.IPOC2023ZT02),China。
文摘Visible light communication(VLC)has attracted much attention in the research of sixthgeneration(6G)systems.Furthermore,channel modeling is the foundation for designing efficient and robust VLC systems.In this paper,we present extensive VLC channel measurement campaigns in indoor environments,i.e.,an office and a corridor.Based on the measured data,the large-scale fading characteristics and multipath-related characteristics,including omnidirectional optical path loss(OPL),K-factor,power angular spectrum(PAS),angle spread(AS),and clustering characteristics,are analyzed and modeled through a statistical method.Based on the extracted statistics of the above-mentioned channel characteristics,we propose a statistical spatial channel model(SSCM)capable of modeling multipath in the spatial domain.Furthermore,the simulated statistics of the proposed model are compared with the measured statistics.For instance,in the office,the simulated path loss exponent(PLE)and the measured PLE are 1.96and 1.97,respectively.And,the simulated medians of AS and measured medians of AS are 25.94°and 24.84°,respectively.Generally,the fact that the simulated results fit well with measured results has demonstrated the accuracy of our SSCM.
基金supported by Nanyang Technological University,Singapore under the Wallenberg-NTU Presidential Postdoctoral Fellowship and the Natural Science Foundation in Heilongjiang Province,China(YQ2022F003).
文摘This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.
文摘Excavation with tunnel boring machine(TBM)can generate vibrations,causing damages to neighbouring buildings and disturbing the residents or the equipment.This problem is particularly challenging in urban areas,where TBMs are increasingly large in diameter and shallow in depth.In response to this problem,four experimental campaigns were carried out in different geotechnical contexts in France.The vibration measurements were acquired on the surface and inside the TBMs.These measurements are also complemented by few data in the literature.An original methodology of signal processing is pro-posed to characterize the amplitude of the particle velocities,as well as the frequency content of the signals to highlight the most energetic bands.The levels of vibrations are also compared with the thresholds existing in various European regulations concerning the impact on neighbouring structures and the disturbance to local residents.
基金the National Natural Science Foundation of China(Grant No.62001083)the Guangdong Provincial Key Research and Development Project,China(Grant No.2020B010179002).
文摘In dielectrometry,traditional analytical and numerical algorithms are difficultly employed in complex resonant cavities.For a special kind of structure(a rotating resonant cavity),the body of revolution finite-element method(BOR-FEM)is employed to calculate the resonant parameters and dielectric parameters.In this paper,several typical resonant structures are selected for analysis and verification.Compared with the resonance parameter values in the literature and the simulation results of commercial software,the error of the BOR-FEM calculation is less than 0.9%and a single solution time is less than 1 s.Reentrant coaxial resonant cavities loaded with dielectric materials are analyzed using this method and compared with simulation results,showing good agreement.Finally,in this paper,the established BOR-FEM method is successfully applied with a machined cavity for the accurate measurement of the complex dielectric constant of dielectric materials.The test specimens were machined from polytetrafluoroethylene,fused silica and Al_(2)O_(3),and the test results showed good agreement with the literature reference values.
基金supported financially by the National Natural Science Foundation of China (NSFC) (Grant No.51775378)the Key Projects in Tianjin Science&Technology Support Program (Grant No.19YFZC GX00890).
文摘Optical and visual measurement technology is used widely in fields that involve geometric measurements,and among such technology are laser and vision-based displacement measuring modules(LVDMMs).The displacement transformation coefficient(DTC)of an LVDMM changes with the coordinates in the camera image coordinate system during the displacement measuring process,and these changes affect the displacement measurement accuracy of LVDMMs in the full field of view(FFOV).To give LVDMMs higher accuracy in the FFOV and make them adaptable to widely varying measurement demands,a new calibration method is proposed to improve the displacement measurement accuracy of LVDMMs in the FFOV.First,an image coordinate system,a pixel measurement coordinate system,and a displacement measurement coordinate system are established on the laser receiving screen of the LVDMM.In addition,marker spots in the FFOV are selected,and the DTCs at the marker spots are obtained from calibration experiments.Also,a fitting method based on locally weighted scatterplot smoothing(LOWESS)is selected,and with this fitting method the distribution functions of the DTCs in the FFOV are obtained based on the DTCs at the marker spots.Finally,the calibrated distribution functions of the DTCs are applied to the LVDMM,and experiments conducted to verify the displacement measurement accuracies are reported.The results show that the FFOV measurement accuracies for horizontal and vertical displacements are better than±15μm and±19μm,respectively,and that for oblique displacement is better than±24μm.Compared with the traditional calibration method,the displacement measurement error in the FFOV is now 90%smaller.This research on an improved calibration method has certain significance for improving the measurement accuracy of LVDMMs in the FFOV,and it provides a new method and idea for other vision-based fields in which camera parameters must be calibrated.
基金supported by the National Natural Science Foundation of China (Nos.Y8113C005C and U1832132)。
文摘A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider (BEPCII). However, the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past. With a reliable kicker structure, a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII. A comparison of the numerical simulation was conducted for three kicker models, demonstrating the comprehensive advantage of the three-metal-strip kicker. Furthermore, impedance bench measurements were conducted on a prototype of a three-metal-strip kicker. The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method. A satisfactory agreement was obtained between the numerical simulations and measurements. Based on the numerical simulation data, the loss factor was 0.01721 V/pC, and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4%of the parasitic loss of the beam was deposited on the metal strips, and the total heat deposition power on the kicker was between 113.3 and 131.5 W. The obtained heat deposition powers can be considered as a reference for establishing the cooling system.
基金supported by the Leading Talent Training Project for Young and Middle-Aged Teacher(A2-0265-22-41).
文摘A novel method to measure the flow rate in a wet gas is presented.Due to the presence of liquid,there is a deviation in the measurement of the gas volume flow rate obtained with standard vortex flow-meters.The proposed method is based on a correction factor determined through the application of an over-reading approach to a bluff body in mist flow.The correction factor is obtained from the slip velocity ratio,i.e.,the ratio of droplet velocity to gas velocity,based on the analysis of the fluid velocity distribution in the pipeline section.It also takes into account relevant theoretical arguments.It is shown that the predicted results fit the experimental results well.
文摘State departments of transportation’s (DOTs) decisions to invest resources to expand or implement intelligent transportation systems (ITS) programs or even retire existing infrastructure need to be based on performance evaluations. Nonetheless, an apparent gap exists between the need for ITS performance measurements and the actual implementation. The evidence available points to challenges in the ITS performance measurement processes. This paper evaluated the state of practice of performance measurement for ITS across the US and provided insights. A comprehensive literature review assessed the use of performance measures by DOTs for monitoring implemented ITS programs. Based on the gaps identified through the literature review, a nationwide qualitative survey was used to gather insights from key stakeholders on the subject matter and presented in this paper. From the data gathered, performance measurement of ITS is fairly integrated into ITS programs by DOTs, with most agencies considering the process beneficial. There, however, exist reasons that prevent agencies from measuring ITS performance to greater detail and quality. These include lack of data, fragmented or incomparable data formats, the complexity of the endeavor, lack of data scientists, and difficulty assigning responsibilities when inter-agency collaboration is required. Additionally, DOTs do not benchmark or compare their ITS performance with others for reasons that include lack of data, lack of guidance or best practices, and incomparable data formats. This paper is relevant as it provides insights expected to guide DOTs and other agencies in developing or reevaluating their ITS performance measurement processes.
文摘Introduction: The elements and perception of beauty vary between populations around the world. To obtain better results, surgical techniques should be planned based on anthropometric characteristics of the race, location, and body mass index (BMI). Objectives: To determine which are the standard measurements and anatomical proportions of the breast in a healthy Mexican women population. Materials and Methods: Female Mexican volunteers between 20 and 60 years of age, without any history of breast illness or breast surgery were studied. Demographic information and standard breast anthropometric measurements were collected manually by one of the authors. For the statistical analysis a Student-T test was performed, and the Pearson correlation coefficient was obtained using the latest version of SPSS software. Results: 78 volunteers were included in the analysis. Mean height, weight and BMI were 1.6 m, 68.9 Kg, and 26.6 Kg/m2 respectively. The mean anthropometric values found were: Supra Sternal notch to nipple distance (SSN:N) 22 cm, Breast volume (BV) 372.6 cm3, Upper breast pole length (UBPL) 11 cm, Lower Breast Pole length (LBPL) 7.7 cm, Midline to Nipple distance (ML:N) 10.2 cm, Transverse diameter of the Nipple areola complex (NAC-T) 4.1 cm, Height of the Nipple Areola Complex (NAC-H) 4.1 cm, Base of the breast (BB) 13.4 cm, Upper Pole to Lower Pole Ratio (UPP:LPP) 58.9:41.1. A statistically significant difference between Right and left breast was not found. The UPP/ LPP ratio in our population is far different from what is considered internationally aesthetic (45:55). A positive correlation was found between weight/ BMI and SSN:N, BV, BB, ML:N and LBPL. Also between age and SSN:N, LBPL, BV and BB. Conclusion: This study sets the Anthropometric grounds in Mexican population for an objective individual patient analysis and comparison with the female population of this and other nations.
文摘As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.
基金supported by the UK Science and Engineering Research Council under contract! GR3/7612.
文摘NOAA AVHRR data from the Bay of Biscay between 1988 and 1990 have been examined in order to extract information on the fluctuations of sea surface temperature (SST) at the diurnal time scale. The temporal and spatial distributions of diurnal warming in the area are obtained. The diurnal warming occurs during the summer months. Large diurnal warming in excess of 1℃ is found within 100 km along the west coast of France and within 30 km along the north coast of Spain. In the central Bay of Biscay the diurnal warming is typically about 0.5℃. The diurnal warming up to 6℃ is observed occasionally in the coastal areas where the wind speed is very low. A one-dimensional oceanic mixed-layer model has been used to simulate the diurnal warming. The results demonstrate that the diurnal warming increases with the decrease of the wind speed and the increase of the net heat flux. The comparison shows that the model results are in good agreement with the satellite measurements.
基金co-funded by Chinese Postdoctoral Science Foundation(2018M640663)the National Natural Science Foundation of China(41474100,41574118,41674131)National Science and Technology Major Project of the Ministry of Science and Technology of China(2017ZX05009-001)
文摘We present systematic investigations on the physics,detection performance and inversion of logging-while-drilling extradeep azimuthal resistivity measurements(EDARM).First,the definitions of EDRAM measurements are discussed,followed by the derivation of the attenuation and phase-shift geometrical factors to illustrate the relative contributions of formation units to the observed signals.Then,a new definition of detection depth,which considers the uncertainty of inversion results caused by the data noise,is proposed to quantify the detection capability of ED ARM.Finally,the B ayesian theory associated with Markov chain Monte Carlo sampling is introduced for fast processing of EDARM data.Numerical results show that ED ARM is capable of detecting the azimuth and distance of remote bed boundaries,and the detection capability increases with increasing spacing and resistivity contrast.The EDARM tool can accommodate a large range of formation resistivity and is able to provide the resistivity anisotropy at arbitrary relative dipping angles.In addition,multiple bed boundaries and reservoir images near the borehole are readily obtained by using the Bayesian inversion.
基金supported by the National Natural Science Foundation of China(Nos.11605248,11605249,11605267,and 11805032.)
文摘A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.
基金the National Key Research and Development Program of China(Grant Nos.2019YFC1510300 and 2018YFC1507900)the National Natural Science Foundation of China(Grant Nos.41575131).
文摘The presence of embedded convection in stratiform clouds strongly affects ice microphysical properties and precipitation formation.In situ aircraft measurements,including upward and downward spirals and horizontal penetrations,were performed within both embedded convective cells and stratiform regions of a mixedphase stratiform cloud system on 22 May 2017.Supercooled liquid water measurements,particle size distributions,and particle habits in different cloud regions were discussed with the intent of characterizing the riming process and determining how particle size distributions vary from convective to stratiform regions.Significant amounts of supercooled liquid water,with maxima up to 0.6 g m−3,were observed between−3℃ and−6℃ in the embedded convective cells while the peak liquid water content was generally less than 0.1 g m−3 in the stratiform regions.There are two distinct differences in particle size distributions between convective and stratiform regions.One difference is the significant shift toward larger particles from upper−15℃ to lower−10℃ in the convective region,with the maximum particle dimensions increasing from less than 6000μm to over 1 cm.The particles larger than 1 cm at−10℃ are composed of dendrites and their aggregates.The other difference is the large concentrations of small particles(25–205μm)at temperatures between−3℃ and−5℃ in the convective region,where rimed ice particles and needles coexist.Needle regions are observed from three of the five spirals,but only the cloud conditions within the convective region fit into the Hallett-Mossop criteria.
基金the National Natural Science Foundation of China(Nos.41974095,41774090,and U1939205)the Special Fund of the Institute of Geophysics,China Earthquake Administration(Nos.DQJB20X09,and DQJB21R30)The first author acknowledges support from the China Postdoctoral Science Foundation(No.2018M641424)。
文摘The terrestrial time-variable gravity measurements are characterized by a high signal-to-noise ratio and sensitivity to the sources of mass change in the Earth's crust.These gravity data have many applications,such as surface deformation,groundwater storage changes,and mass migration before and after earthquakes.Based on repeated terrestrial gravity measurements at 198 gravity stations in the Sichuan-Yunnan region(SYR)from 2015 to 2017,we determine a time series of degree 120 gravity fields using the localized spherical harmonic(Slepian)basis functions.Our results show that adopting the first 6 Slepian basis functions is sufficient for effective localized Slepian modeling in the SYR.The differences between two gravity campaigns at the same time of year show an obvious correlation with tectonic features.The degree 120 timevariable gravity models presented in this paper will benefit the study of the regional mass migration inside the crust of the SYR and supplement the existing geophysical models for the China Seismic Experimental Site.
文摘A Kelvin probe was used as reference in this study on electrochemical measurements of a simulatedmarine atmospheric corrosion system (electrode covered by a very thin electrolyte layer). The experimentalsetups for improved measurements proved satisfactory for the conventional steady-state electrochemicalmeasurements in atmospheric studies.
