Amplitudes have been found to be a function of incident angle and offset. Hence data required to test for amplitude variation with angle or offset needs to have its amplitudes for all offsets preserved and not stacked...Amplitudes have been found to be a function of incident angle and offset. Hence data required to test for amplitude variation with angle or offset needs to have its amplitudes for all offsets preserved and not stacked. Amplitude Variation with Offset (AVO)/Amplitude Variation with Angle (AVA) is necessary to account for information in the offset/angle parameter (mode converted S-wave and P-wave velocities). Since amplitudes are a function of the converted S- and P-waves, it is important to investigate the dependence of amplitudes on the elastic (P- and S-waves) parameters from the seismic data. By modelling these effects for different reservoir fluids via fluid substitution, various AVO geobody classes present along the well and in the entire seismic cube can be observed. AVO analysis was performed on one test well (Well_1) and 3D pre-stack angle gathers from the Tano Basin. The analysis involves creating a synthetic model to infer the effect of offset scaling techniques on amplitude responses in the Tano basin as compared to the effect of unscaled seismic data. The spectral balance process was performed to match the amplitude spectra of all angle stacks to that of the mid (26°) stack on the test lines. The process had an effect primarily on the far (34° - 40°) stacks. The frequency content of these stacks slightly increased to match that of the near and mid stacks. In offset scaling process, the root mean square (RMS) amplitude comparison between the synthetic and seismic suggests that the amplitude of the far traces should be reduced relative to the nears by up to 16%. However, the exact scaler values depend on the time window considered. This suggests that the amplitude scaling with offset delivered from seismic processing is only approximately correct and needs to be checked with well synthetics and adjusted accordingly prior to use for AVO studies. The AVO attribute volumes generated were better at resolving anomalies on spectrally balanced and offset scaled data than data delivered from conventional processing. A typical class II AVO anomaly is seen along the test well from the cross-plot analysis and AVO attribute cube which indicates an oil filled reservoir.展开更多
We show an example of a bounded potential on the half-line obtained as the image of an Inverse Transformation Operator of the Bessel singular potential of the Reduced Radial Schrödinger Equation, and show us ...We show an example of a bounded potential on the half-line obtained as the image of an Inverse Transformation Operator of the Bessel singular potential of the Reduced Radial Schrödinger Equation, and show us the Estimates of the A(α) amplitude.展开更多
To increase the storage capacity in holographic data storage(HDS),the information to be stored is encoded into a complex amplitude.Fast and accurate retrieval of amplitude and phase from the reconstructed beam is nece...To increase the storage capacity in holographic data storage(HDS),the information to be stored is encoded into a complex amplitude.Fast and accurate retrieval of amplitude and phase from the reconstructed beam is necessary during data readout in HDS.In this study,we proposed a complex amplitude demodulation method based on deep learning from a single-shot diffraction intensity image and verified it by a non-interferometric lensless experiment demodulating four-level amplitude and four-level phase.By analyzing the correlation between the diffraction intensity features and the amplitude and phase encoding data pages,the inverse problem was decomposed into two backward operators denoted by two convolutional neural networks(CNNs)to demodulate amplitude and phase respectively.The experimental system is simple,stable,and robust,and it only needs a single diffraction image to realize the direct demodulation of both amplitude and phase.To our investigation,this is the first time in HDS that multilevel complex amplitude demodulation is achieved experimentally from one diffraction intensity image without iterations.展开更多
Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60were prepared,and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric...Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60were prepared,and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric stress amplitudes.The samples were subjected to 10,000 loading-unloading cycles with a frequency of 8 Hz.At each level of confining pressure,the applied cyclic deviatoric stress amplitude was increased incrementally until excessive deformation of the jointed rock specimen was observed.Analysis of the test results indicated that there existed a critical cyclic deviatoric stress amplitude(i.e.critical dynamic deviatoric stress)beyond which the jointed rock specimens yielded.The measured critical dynamic deviatoric stress was less than the corresponding static deviatoric stress.At cyclic deviatoric stress amplitudes less than the critical dynamic deviatoric stress,minor cumulative residual axial strains were observed,resulting in hysteretic damping.However,for cyclic deviatoric stresses beyond the critical dynamic deviatoric stress,the plastic strains increased promptly,and the resilient moduli degraded rapidly during the initial loading cycles.Cyclic triaxial test results showed that at higher confining pressures,the ultimate residual axial strain attained by the jointed rock specimen decreased,the steadystate dissipated energy density and steady-state damping ratio per load cycle decreased,while steadystate resilient moduli increased.展开更多
This paper is dedicated to applying the Fourier amplitude sensitivity test(FAST)method to the problem of mixed extension and inflation of a circular cylindrical tube in the presence of residual stresses.The metafuncti...This paper is dedicated to applying the Fourier amplitude sensitivity test(FAST)method to the problem of mixed extension and inflation of a circular cylindrical tube in the presence of residual stresses.The metafunctions and the Ishigami function are considered in the sensitivity analysis(SA).The effects of the input variables on the output variables are investigated,and the most important parameters of the system under the applied pressure and axial force such as the axial stretch and the azimuthal stretch are determined.展开更多
Before the implementation of offshore oil and gas exploitation,it is essential to understand the various factors that influence the stability of submarine sediments surrounding the project.Considering the factors such...Before the implementation of offshore oil and gas exploitation,it is essential to understand the various factors that influence the stability of submarine sediments surrounding the project.Considering the factors such as cost and operability,it is not feasible to assess the physical-mechanical properties of sediments covering the entire region by borehole sampling.In this study,the correlation between near seafloor seismic amplitude and the mean shear strength of shallow sediments was explored using seismic and core testing data from the northern continental slope area of the South China Sea.Results showed that the mean water content of sediments in the layer up to 12 m below the seafloor(mbsf)gradually increased with increasing water depth,and the mean shear strength tended to decrease rapidly near the 1000 m depth contour.The near seafloor seismic amplitude could reflect the mean shear strength of sediments in the 12 mbsf layer under seismic frequency of 65 Hz and wave velocity of 1600 m/s.When the mean shear strength was greater than 10 kPa or the water depth was less than 1000 m,there was a significant linear positive correlation between mean shear strength and near seafloor seismic amplitude.Otherwise,there was a significant linear negative correlation between mean shear strength and near seafloor seismic amplitude.On the basis of these correlations,the pattern of shear strength was estimated from near seafloor seismic amplitude and mapped.The mean shear strength of sediments above 12 mbsf gradually decreased with increasing water depth in the continental slope area,whereas little change occurred in the continental shelf and the end of the canyon.Within the canyon area,the mean shear strength of sediments was characterized by larger values in both sides of the canyon walls and smaller values in the canyon bottom,which was consistent with the infinite slope stability theory.The study provides a method for using near seafloor seismic amplitude data to guide sediment sampling design,and presents a continuous dataset of sediment strength for the simulation of regional sediment stability.展开更多
Although chaotic signals are considered to have great potential applications in radar and communication engineering,their broadband spectrum makes it difficult to design an applicable amplifier or an attenuator for am...Although chaotic signals are considered to have great potential applications in radar and communication engineering,their broadband spectrum makes it difficult to design an applicable amplifier or an attenuator for amplitude conditioning.Moreover, the transformation between a unipolar signal and a bipolar signal is often required. In this paper, a more intelligent hardware implementation based on field programmable analog array(FPAA) is constructed for chaotic systems with complete amplitude control. Firstly, two chaotic systems with complete amplitude control are introduced, one of which has the property of offset boosting with total amplitude control, while the other has offset boosting and a parameter for partial control. Both cases can achieve complete amplitude control including amplitude rescaling and offset boosting. Secondly,linear synchronization is established based on the special structure of chaotic system. Finally, experimental circuits are constructed on an FPAA where the predicted amplitude control is realized through only two independent configurable analog module(CAM) gain values.展开更多
Today ultrasonic power technique is consider a mandatory technique which is always entered in many processes such as in metal and plastic welding to overcomes many issues,with aided of applying force(pressure)and supp...Today ultrasonic power technique is consider a mandatory technique which is always entered in many processes such as in metal and plastic welding to overcomes many issues,with aided of applying force(pressure)and supplied high frequency vibration,a solid-state weld can be generated by ultrasonic metal welding technique.That gives a technique the ability to join not only a small component,whereas also to join thicker specimens,which depends on a proper control of matching welding conditions.Therefore a welding performance can be studied and compared after designed welding horn to resonance at frequencies of 20 kHz and 40 kHz.The analyses of the designed horn are completed through use a vibration mathematical expressions,modal and harmonic analyses to ensure the weldability due to applying ultrasonic power to the working area and also to compare the performance of joint at using two resonance frequencies of 20 kHz and 40 kHz.The dimensions of the horns were determined to match the selected resonance frequencies,which the lengths were calculated as 132 mm and 66 mm respectively.The analysis of the exciting model indicates that the axial vibration modes of 19,584 Hz and 39,794 Hz are obtained in 10th mode,while the two frequency values are recorded 19,600 Hz and 39,800 Hz from the frequency response of the two horns.The weld strength between Al and Cu specimens with a thickness 0.5 mm was evaluated using a tensile test,which the analyses were obtained under using different welding pressure and varied amplitudes.The results were recorded within exciting a horn with two different resonance frequencies,show the enhancement of weld strength and quality through control of stepping amplitude,the enhancement means obtain good strength of the weld,reduce sticking horn to specimen,and lower specimen marking.展开更多
I propose a new algorithm that uses recursive relations to compute spectroscopic factor, pair transfer amplitude and cluster transfer amplitude. I demonstrate the algorithm that it can be calculated very quickly and s...I propose a new algorithm that uses recursive relations to compute spectroscopic factor, pair transfer amplitude and cluster transfer amplitude. I demonstrate the algorithm that it can be calculated very quickly and stored within small computer memory consumption. In BCS case, the particle number is always conserved and the time-consuming projection is avoided. I drive analytical expressions for the pair transfer amplitude and the cluster transfer amplitude expressed by asymmetry many-pair density matrix. This algorithm practically could be used in all of the nuclear double beta decay fields, the heavy cluster emission fields and the single-nucleon transfer of the odd-mass isotopes.展开更多
An fKdV equation of two-layer flow and an averaged fKdV equation（AfKdV equation）with respect to phase are derived to determine the theoreticalamplitude and period of the precursor solitons in the present paper.In te...An fKdV equation of two-layer flow and an averaged fKdV equation（AfKdV equation）with respect to phase are derived to determine the theoreticalamplitude and period of the precursor solitons in the present paper.In terms ofthe AfKdV equation derived by the authors,a new theory on the precursor solitongeneration based on Lee et al.’s concept is presented.Concepts of asymptotic meanhydraulic fall and level are introduced in our analysis,and the theoretical amplitudeand period both depend on the asymptotic mean levels and stratified parameters.From the present theoretical results,it is obtained that when the moving velocityof the topography is at the resonant points,there exist two general relations:（1）amplitude relation （?）=2F,（2）period relation（?）=-8m1m<sub>3</sub><sup>-1</sup>6m<sub>4</sub>m<sub>3</sub><sup>-1</sup><sup>1/2</sup>.F,in which（?）and （?）are the amplitude and period of the precursor solitons at the resonantpoints respectively,m<sub>1</sub>,m<sub>3</sub> and m<sub>4</sub> are coefficients of the fKdV equation,and F isan asymptotic mean half-hydraulic fall at subcritical cutoff points.The theoreticalresults of this paper are compared with experiments and numerical calculations of two-layer flow over a semicircular topography and all these results are in good agreement.Due to the canonical character of the coefficients of fKdV equations,this theory alsoholds for any two-dimensional system,which can be reduced to fKdV equations.展开更多
With the large-scale construction of underground gas storage in salt deposit, much more efforts have been made to assess the fatigue properties of rock salt. The fatigue damage processes the primary, steady,and accele...With the large-scale construction of underground gas storage in salt deposit, much more efforts have been made to assess the fatigue properties of rock salt. The fatigue damage processes the primary, steady,and accelerated phases, which is similar to the axial irrecoverable deformation compiled from the loci of the loading cycles of rock salt. The cumulative fatigue damage increases with a decrease in the loading frequency and with an increase in the stress amplitude within the range tested. To take into account the effects of loading frequency and amplitude on the fatigue behavior of rock salt subjected to cyclic loading, a low cycle fatigue damage model was exclusively established combined with the Manson–Coffin formula. The proposed damage evolution equation was validated with experimental results and proved to be efficient in the prediction of fatigue damage tendency of rock salt under different loading frequencies and amplitudes.展开更多
The Liwan(Lw) gas field located in the northern slope of the South China Sea(SCS) is extremely complex for its seafloor topograghy, which is a huge challenge for the safety of subsea facilities. It is economically imp...The Liwan(Lw) gas field located in the northern slope of the South China Sea(SCS) is extremely complex for its seafloor topograghy, which is a huge challenge for the safety of subsea facilities. It is economically impractical to obtain parameters for risk assessment of slope stability through a large amount of sampling over the whole field. The linkage between soil shear strength and seabed peak amplitude derived from 2D/3D seismic data is helpful for understanding the regional slope-instability risk. In this paper, the relationships among seabed peak, acoustic impedance and shear strength of shallow soil in the study area were discussed based on statistical analysis results. We obtained a similar relationship to that obtained in other deep-water areas. There is a positive correlation between seabed peak amplitude and acoustic impedance and an exponential relationship between acoustic impedance and shear strength of sediment. The acoustic impedance is the key factor linking the seismic amplitude and shear strength. Infinite slope stability analysis results indicate the areas have a high potential of shallow landslide on slopes exceeding 15? when the thickness of loose sediments exceeds 8 m in the Lw gas field. Our prediction shows that they are mainly located in the heads and walls of submarine canyons.展开更多
Low cycle fatigue behavior of extruded AZ80 magnesium alloy was investigated under uniaxial tension-compression at different strain amplitudes and strain rates.The results show that the extruded AZ80 magnesium alloy e...Low cycle fatigue behavior of extruded AZ80 magnesium alloy was investigated under uniaxial tension-compression at different strain amplitudes and strain rates.The results show that the extruded AZ80 magnesium alloy exhibits cyclic hardening at strain amplitudes ranging from 0.4%to 1.0%,the asymmetry of hysteresis loops becomes increasingly obvious when the strain amplitude increases.Higher strain rates correspond to higher stress amplitudes,high mean stresses and short fatigue life.{10–12}extension twins play a role in the cyclic deformation under higher strain amplitudes(0.8%,1.0%).The relationship between total strain energy density and fatigue life can be described by the modified Morrow model.The effect of strain rate on the fatigue life can also be predicted by the model.展开更多
AIM: To investigate the effects of body mass index (BMI) on intraocular pressure (IOP) and ocular pulse amplitude(OPA). METHODS: Totally 140 healthy individuals without any systemic diseases were included in the study...AIM: To investigate the effects of body mass index (BMI) on intraocular pressure (IOP) and ocular pulse amplitude(OPA). METHODS: Totally 140 healthy individuals without any systemic diseases were included in the study. BMI (kg/m2) was calculated for every individual. IOP and OPA were measured with Pascal Dynamic contour tonometer (DCT). Blood pressure was also measured along with the DCT. The patients were divided into three groups according to BMI as: Group1, BMI<25; Group2, 25≤BMI<30; Group3, BMI≥30. Mean values of IOP, OPA, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were used in statistical analysis.RESULTS: In Group1, the means of IOP, OPA, were 16.8±2.3mmHg, 2.7±0.7mmHg respectively; and SBP, DBP were 120.0±6.1mmHg, and 77.4±5.6mmHg respectively. In group2, the mean IOP, OPA, SBP, and DBP were found to be 16.6±2.1mmHg, 2.4±0.7mmHg, 121.7±5.3mmHg, and 79.5±4.9mmHg respectively. In group3, the mean IOP, OPA, SBP, and DBP were found to be 17.3±1.7mmHg, 2.1±0.7mmHg, 122.4±5.7mmHg, and 79.7±5.2mmHg respectively. There were no statistically significant difference between groups in terms of IOP, SBP and DBP, while OPA values were significantly lower in group3 (P=0.001). CONCLUSION: Decreased OPA values in individuals with higher BMI may indicate that subjects with higher BMI have lower choroidal perfusion and lower ocular blood flow.展开更多
This paper presents a method to estimate beam pointing of phased array radar by the pulse amplitude train, which is significant in radar electronic reconnaissance and electronic support measure. Firstly, the antenna p...This paper presents a method to estimate beam pointing of phased array radar by the pulse amplitude train, which is significant in radar electronic reconnaissance and electronic support measure. Firstly, the antenna patterns modeling of the phased array system is exploited to build the radar sweeping model and the signal propagation model. Secondly, the relationship between the variation of the radiated power and the antenna beam pointing angles in the given airspace is analyzed. Based on the above two points, the sample with obvious amplitude characteristics of the pulse amplitude train can be screened out after detecting the train peaks. Finally, the sample is matched to the subsequent pulse amplitude train based on the Hausdorff distance. The proposed methods have less prior knowledge and higher efficiency and are easier to process. By cross correlating the sample of the pulse amplitude train with the sample data of the antenna follow-up radiation, the probability of detection of the beam pointing direction becomes larger in case that the subsequent antenna beam returns to the specific position.展开更多
A conventional multi-channel pulse amplitude analyzer acquires single energy spectrum,but provides no information on its tendency with time.To address the limitation,we propose a scheme of time-sharing multichannel pu...A conventional multi-channel pulse amplitude analyzer acquires single energy spectrum,but provides no information on its tendency with time.To address the limitation,we propose a scheme of time-sharing multichannel pulse amplitude analyzer(TSMCA).A dual-port random access memory is divided into two storage spaces,one for current energy spectrum data acquisition and another for previous energy spectrum data storage.The two tasks can be performed simultaneously,and the time-related variation tendency of energy spectrum can be obtained.A prototype system of TSMCA is designed.It performs nicely,with maximum channel number of 4096 in capacity of 2^(32)/Ch,minimal time-sharing slice of 25 ms,the differential nonlinearity of <1.5%,and the integral nonlinearity of <0.3%.展开更多
BACKGROUND Diabetes mellitus is a metabolic disorder characterized by prolonged elevation of blood glucose due to various causes.Currently,the relationship between diabetic retinopathy(DR)and altered connectivity of b...BACKGROUND Diabetes mellitus is a metabolic disorder characterized by prolonged elevation of blood glucose due to various causes.Currently,the relationship between diabetic retinopathy(DR)and altered connectivity of brain function is unclear.AIM To investigate the relationship between this brain activity and clinical manifestations and behaviors of DR patients by using the amplitude of low-frequency fluctuation(ALFF)technique.METHODS Twenty-four DR patients and 24 healthy controls(HCs)matched for age and gender were enrolled.We measured and recorded average ALFF values of DR patients and HCs and then classified them using receiver operating characteristic(ROC)curves.RESULTS ALFF values of both left and right posterior cerebellar lobe and right anterior cingulate gyrus were remarkably higher in the DR patients than in the HCs;however,DR patients had lower values in the bilateral calcarine area.ROC curve analysis of different brain regions demonstrated high accuracy in the area under the curve analysis.There was no significant relationship between mean ALFF values for different regions and clinical presentations in DR patients.Neuronal synchronization abnormalities in some brain regions of DR patients were associated with cognitive and visual disorders.CONCLUSION Abnormal spontaneous brain activity was observed in many areas of DR patients’brains,which may suggest a possible link between clinical manifestations and behaviors in DR patients.展开更多
Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the pres...Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the presence of a local RF(LO RF)field.In this study,we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation(AM)of the LO RF field;that is,the phase of the SIG RF field is related to both the amplitude and phase of the beat signal.When the AM frequency of the LO RF field is the same as the frequency of the beat signal,the beat signal will further interfere with the AM of the LO RF field inside the atom,and then the amplitude of the beat signal is related to the phase of the SIG RF field.The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 toπ/2 when the phase of the AM is set with a differenceπ/4 from the phase of the LO RF field.The minimum phase resolution can be as small as 0.6°by optimizing the experimental conditions according to a simple theoretical model.This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.展开更多
The variations in the wave energy and the amplitude along the energy dispersion paths of the barotropic Rossby waves in zonally symmetric basic flow are studied by solving the wave energy equation,which expresses that...The variations in the wave energy and the amplitude along the energy dispersion paths of the barotropic Rossby waves in zonally symmetric basic flow are studied by solving the wave energy equation,which expresses that the wave energy variability is determined by the divergence of the group velocity and the energy budget from the basic flow.The results suggest that both the wave energy and the amplitude of a leading wave increase significantly in the propagating region that is located south of the jet axis and enclosed by a southern critical line and a northern turning latitude.The leading wave gains the barotropic energy from the basic flow by eddy activities.The amplitude continuously climbs up a peak at the turning latitude due to increasing wave energy and enlarging horizontal scale(shrinking total wavenumber).Both the wave energy and the amplitude eventually decrease when the trailing wave continuously approaches southward to the critical line.The trailing wave decays and its energy is continuously absorbed by the basic flow.Furthermore,both the wave energy and the amplitude oscillate with a limited range in the propagating region that is located near the jet axis and enclosed by two turning latitudes.Both the leading and trailing waves neither develop nor decay significantly.The jet works as a waveguide to allow the waves to propagate a long distance.展开更多
文摘Amplitudes have been found to be a function of incident angle and offset. Hence data required to test for amplitude variation with angle or offset needs to have its amplitudes for all offsets preserved and not stacked. Amplitude Variation with Offset (AVO)/Amplitude Variation with Angle (AVA) is necessary to account for information in the offset/angle parameter (mode converted S-wave and P-wave velocities). Since amplitudes are a function of the converted S- and P-waves, it is important to investigate the dependence of amplitudes on the elastic (P- and S-waves) parameters from the seismic data. By modelling these effects for different reservoir fluids via fluid substitution, various AVO geobody classes present along the well and in the entire seismic cube can be observed. AVO analysis was performed on one test well (Well_1) and 3D pre-stack angle gathers from the Tano Basin. The analysis involves creating a synthetic model to infer the effect of offset scaling techniques on amplitude responses in the Tano basin as compared to the effect of unscaled seismic data. The spectral balance process was performed to match the amplitude spectra of all angle stacks to that of the mid (26°) stack on the test lines. The process had an effect primarily on the far (34° - 40°) stacks. The frequency content of these stacks slightly increased to match that of the near and mid stacks. In offset scaling process, the root mean square (RMS) amplitude comparison between the synthetic and seismic suggests that the amplitude of the far traces should be reduced relative to the nears by up to 16%. However, the exact scaler values depend on the time window considered. This suggests that the amplitude scaling with offset delivered from seismic processing is only approximately correct and needs to be checked with well synthetics and adjusted accordingly prior to use for AVO studies. The AVO attribute volumes generated were better at resolving anomalies on spectrally balanced and offset scaled data than data delivered from conventional processing. A typical class II AVO anomaly is seen along the test well from the cross-plot analysis and AVO attribute cube which indicates an oil filled reservoir.
文摘We show an example of a bounded potential on the half-line obtained as the image of an Inverse Transformation Operator of the Bessel singular potential of the Reduced Radial Schrödinger Equation, and show us the Estimates of the A(α) amplitude.
基金We are grateful for financial supports from National Key Research and Development Program of China(2018YFA0701800)Project of Fujian Province Major Science and Technology(2020HZ01012)+1 种基金Natural Science Foundation of Fujian Province(2021J01160)National Natural Science Foundation of China(62061136005).
文摘To increase the storage capacity in holographic data storage(HDS),the information to be stored is encoded into a complex amplitude.Fast and accurate retrieval of amplitude and phase from the reconstructed beam is necessary during data readout in HDS.In this study,we proposed a complex amplitude demodulation method based on deep learning from a single-shot diffraction intensity image and verified it by a non-interferometric lensless experiment demodulating four-level amplitude and four-level phase.By analyzing the correlation between the diffraction intensity features and the amplitude and phase encoding data pages,the inverse problem was decomposed into two backward operators denoted by two convolutional neural networks(CNNs)to demodulate amplitude and phase respectively.The experimental system is simple,stable,and robust,and it only needs a single diffraction image to realize the direct demodulation of both amplitude and phase.To our investigation,this is the first time in HDS that multilevel complex amplitude demodulation is achieved experimentally from one diffraction intensity image without iterations.
文摘Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60were prepared,and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric stress amplitudes.The samples were subjected to 10,000 loading-unloading cycles with a frequency of 8 Hz.At each level of confining pressure,the applied cyclic deviatoric stress amplitude was increased incrementally until excessive deformation of the jointed rock specimen was observed.Analysis of the test results indicated that there existed a critical cyclic deviatoric stress amplitude(i.e.critical dynamic deviatoric stress)beyond which the jointed rock specimens yielded.The measured critical dynamic deviatoric stress was less than the corresponding static deviatoric stress.At cyclic deviatoric stress amplitudes less than the critical dynamic deviatoric stress,minor cumulative residual axial strains were observed,resulting in hysteretic damping.However,for cyclic deviatoric stresses beyond the critical dynamic deviatoric stress,the plastic strains increased promptly,and the resilient moduli degraded rapidly during the initial loading cycles.Cyclic triaxial test results showed that at higher confining pressures,the ultimate residual axial strain attained by the jointed rock specimen decreased,the steadystate dissipated energy density and steady-state damping ratio per load cycle decreased,while steadystate resilient moduli increased.
文摘This paper is dedicated to applying the Fourier amplitude sensitivity test(FAST)method to the problem of mixed extension and inflation of a circular cylindrical tube in the presence of residual stresses.The metafunctions and the Ishigami function are considered in the sensitivity analysis(SA).The effects of the input variables on the output variables are investigated,and the most important parameters of the system under the applied pressure and axial force such as the axial stretch and the azimuthal stretch are determined.
基金The National Natural Science Foundation of China under contract No.41706065the Basic Scientific Fund for National Public Research Institutes of China under contract No.2015G08+1 种基金the NSFC-Shandong Joint Fund for Marine Science Research Centers of China under contract No.U1606401the National Program on Global Change and Air-sea Interaction of China under contract No.GASI-GEOGE-05.
文摘Before the implementation of offshore oil and gas exploitation,it is essential to understand the various factors that influence the stability of submarine sediments surrounding the project.Considering the factors such as cost and operability,it is not feasible to assess the physical-mechanical properties of sediments covering the entire region by borehole sampling.In this study,the correlation between near seafloor seismic amplitude and the mean shear strength of shallow sediments was explored using seismic and core testing data from the northern continental slope area of the South China Sea.Results showed that the mean water content of sediments in the layer up to 12 m below the seafloor(mbsf)gradually increased with increasing water depth,and the mean shear strength tended to decrease rapidly near the 1000 m depth contour.The near seafloor seismic amplitude could reflect the mean shear strength of sediments in the 12 mbsf layer under seismic frequency of 65 Hz and wave velocity of 1600 m/s.When the mean shear strength was greater than 10 kPa or the water depth was less than 1000 m,there was a significant linear positive correlation between mean shear strength and near seafloor seismic amplitude.Otherwise,there was a significant linear negative correlation between mean shear strength and near seafloor seismic amplitude.On the basis of these correlations,the pattern of shear strength was estimated from near seafloor seismic amplitude and mapped.The mean shear strength of sediments above 12 mbsf gradually decreased with increasing water depth in the continental slope area,whereas little change occurred in the continental shelf and the end of the canyon.Within the canyon area,the mean shear strength of sediments was characterized by larger values in both sides of the canyon walls and smaller values in the canyon bottom,which was consistent with the infinite slope stability theory.The study provides a method for using near seafloor seismic amplitude data to guide sediment sampling design,and presents a continuous dataset of sediment strength for the simulation of regional sediment stability.
基金Project supported by the Startup Foundation for Introducing Talent of Nanjing University of Information Science&Technology,China(Grant No.2016205)the Natural Science Foundation of the Jiangsu Higher Education Institutions of Jiangsu Province,China(Grant No.16KJB120004)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Natural Science Foundation of Hebei Province,China(Grant No.A2015108010)
文摘Although chaotic signals are considered to have great potential applications in radar and communication engineering,their broadband spectrum makes it difficult to design an applicable amplifier or an attenuator for amplitude conditioning.Moreover, the transformation between a unipolar signal and a bipolar signal is often required. In this paper, a more intelligent hardware implementation based on field programmable analog array(FPAA) is constructed for chaotic systems with complete amplitude control. Firstly, two chaotic systems with complete amplitude control are introduced, one of which has the property of offset boosting with total amplitude control, while the other has offset boosting and a parameter for partial control. Both cases can achieve complete amplitude control including amplitude rescaling and offset boosting. Secondly,linear synchronization is established based on the special structure of chaotic system. Finally, experimental circuits are constructed on an FPAA where the predicted amplitude control is realized through only two independent configurable analog module(CAM) gain values.
文摘Today ultrasonic power technique is consider a mandatory technique which is always entered in many processes such as in metal and plastic welding to overcomes many issues,with aided of applying force(pressure)and supplied high frequency vibration,a solid-state weld can be generated by ultrasonic metal welding technique.That gives a technique the ability to join not only a small component,whereas also to join thicker specimens,which depends on a proper control of matching welding conditions.Therefore a welding performance can be studied and compared after designed welding horn to resonance at frequencies of 20 kHz and 40 kHz.The analyses of the designed horn are completed through use a vibration mathematical expressions,modal and harmonic analyses to ensure the weldability due to applying ultrasonic power to the working area and also to compare the performance of joint at using two resonance frequencies of 20 kHz and 40 kHz.The dimensions of the horns were determined to match the selected resonance frequencies,which the lengths were calculated as 132 mm and 66 mm respectively.The analysis of the exciting model indicates that the axial vibration modes of 19,584 Hz and 39,794 Hz are obtained in 10th mode,while the two frequency values are recorded 19,600 Hz and 39,800 Hz from the frequency response of the two horns.The weld strength between Al and Cu specimens with a thickness 0.5 mm was evaluated using a tensile test,which the analyses were obtained under using different welding pressure and varied amplitudes.The results were recorded within exciting a horn with two different resonance frequencies,show the enhancement of weld strength and quality through control of stepping amplitude,the enhancement means obtain good strength of the weld,reduce sticking horn to specimen,and lower specimen marking.
文摘I propose a new algorithm that uses recursive relations to compute spectroscopic factor, pair transfer amplitude and cluster transfer amplitude. I demonstrate the algorithm that it can be calculated very quickly and stored within small computer memory consumption. In BCS case, the particle number is always conserved and the time-consuming projection is avoided. I drive analytical expressions for the pair transfer amplitude and the cluster transfer amplitude expressed by asymmetry many-pair density matrix. This algorithm practically could be used in all of the nuclear double beta decay fields, the heavy cluster emission fields and the single-nucleon transfer of the odd-mass isotopes.
基金The project supported by the foundation of The State Education Commission"The dynamics of upper ocean"the open grants of Physical Oceanography Laboratory
文摘An fKdV equation of two-layer flow and an averaged fKdV equation（AfKdV equation）with respect to phase are derived to determine the theoreticalamplitude and period of the precursor solitons in the present paper.In terms ofthe AfKdV equation derived by the authors,a new theory on the precursor solitongeneration based on Lee et al.’s concept is presented.Concepts of asymptotic meanhydraulic fall and level are introduced in our analysis,and the theoretical amplitudeand period both depend on the asymptotic mean levels and stratified parameters.From the present theoretical results,it is obtained that when the moving velocityof the topography is at the resonant points,there exist two general relations:（1）amplitude relation （?）=2F,（2）period relation（?）=-8m1m<sub>3</sub><sup>-1</sup>6m<sub>4</sub>m<sub>3</sub><sup>-1</sup><sup>1/2</sup>.F,in which（?）and （?）are the amplitude and period of the precursor solitons at the resonantpoints respectively,m<sub>1</sub>,m<sub>3</sub> and m<sub>4</sub> are coefficients of the fKdV equation,and F isan asymptotic mean half-hydraulic fall at subcritical cutoff points.The theoreticalresults of this paper are compared with experiments and numerical calculations of two-layer flow over a semicircular topography and all these results are in good agreement.Due to the canonical character of the coefficients of fKdV equations,this theory alsoholds for any two-dimensional system,which can be reduced to fKdV equations.
基金fundings and supports of the National Basic Research Program of China (No. 2013CB036005)the National Natural Science Foundation of China (Nos. 51309234, 51527810, 51304219, and 51021001)+2 种基金the Natural Science Foundation of Jiangsu Province of China (No. BK20130065)the Open Foundation of State Key Laboratory for Geomechanics and Deep Underground Engineering of China (No. SKLGDUEK1403)the China Postdoctoral Science Foundation (No. 2015M570451)
文摘With the large-scale construction of underground gas storage in salt deposit, much more efforts have been made to assess the fatigue properties of rock salt. The fatigue damage processes the primary, steady,and accelerated phases, which is similar to the axial irrecoverable deformation compiled from the loci of the loading cycles of rock salt. The cumulative fatigue damage increases with a decrease in the loading frequency and with an increase in the stress amplitude within the range tested. To take into account the effects of loading frequency and amplitude on the fatigue behavior of rock salt subjected to cyclic loading, a low cycle fatigue damage model was exclusively established combined with the Manson–Coffin formula. The proposed damage evolution equation was validated with experimental results and proved to be efficient in the prediction of fatigue damage tendency of rock salt under different loading frequencies and amplitudes.
基金funded by China National Science and Technology Major Project (No.2011ZX05056-001-02)
文摘The Liwan(Lw) gas field located in the northern slope of the South China Sea(SCS) is extremely complex for its seafloor topograghy, which is a huge challenge for the safety of subsea facilities. It is economically impractical to obtain parameters for risk assessment of slope stability through a large amount of sampling over the whole field. The linkage between soil shear strength and seabed peak amplitude derived from 2D/3D seismic data is helpful for understanding the regional slope-instability risk. In this paper, the relationships among seabed peak, acoustic impedance and shear strength of shallow soil in the study area were discussed based on statistical analysis results. We obtained a similar relationship to that obtained in other deep-water areas. There is a positive correlation between seabed peak amplitude and acoustic impedance and an exponential relationship between acoustic impedance and shear strength of sediment. The acoustic impedance is the key factor linking the seismic amplitude and shear strength. Infinite slope stability analysis results indicate the areas have a high potential of shallow landslide on slopes exceeding 15? when the thickness of loose sediments exceeds 8 m in the Lw gas field. Our prediction shows that they are mainly located in the heads and walls of submarine canyons.
基金the National Basic Research Program of China(No.2013CB632205).
文摘Low cycle fatigue behavior of extruded AZ80 magnesium alloy was investigated under uniaxial tension-compression at different strain amplitudes and strain rates.The results show that the extruded AZ80 magnesium alloy exhibits cyclic hardening at strain amplitudes ranging from 0.4%to 1.0%,the asymmetry of hysteresis loops becomes increasingly obvious when the strain amplitude increases.Higher strain rates correspond to higher stress amplitudes,high mean stresses and short fatigue life.{10–12}extension twins play a role in the cyclic deformation under higher strain amplitudes(0.8%,1.0%).The relationship between total strain energy density and fatigue life can be described by the modified Morrow model.The effect of strain rate on the fatigue life can also be predicted by the model.
文摘AIM: To investigate the effects of body mass index (BMI) on intraocular pressure (IOP) and ocular pulse amplitude(OPA). METHODS: Totally 140 healthy individuals without any systemic diseases were included in the study. BMI (kg/m2) was calculated for every individual. IOP and OPA were measured with Pascal Dynamic contour tonometer (DCT). Blood pressure was also measured along with the DCT. The patients were divided into three groups according to BMI as: Group1, BMI<25; Group2, 25≤BMI<30; Group3, BMI≥30. Mean values of IOP, OPA, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were used in statistical analysis.RESULTS: In Group1, the means of IOP, OPA, were 16.8±2.3mmHg, 2.7±0.7mmHg respectively; and SBP, DBP were 120.0±6.1mmHg, and 77.4±5.6mmHg respectively. In group2, the mean IOP, OPA, SBP, and DBP were found to be 16.6±2.1mmHg, 2.4±0.7mmHg, 121.7±5.3mmHg, and 79.5±4.9mmHg respectively. In group3, the mean IOP, OPA, SBP, and DBP were found to be 17.3±1.7mmHg, 2.1±0.7mmHg, 122.4±5.7mmHg, and 79.7±5.2mmHg respectively. There were no statistically significant difference between groups in terms of IOP, SBP and DBP, while OPA values were significantly lower in group3 (P=0.001). CONCLUSION: Decreased OPA values in individuals with higher BMI may indicate that subjects with higher BMI have lower choroidal perfusion and lower ocular blood flow.
基金supported by the National Natural Science Foundation of China(61501501)
文摘This paper presents a method to estimate beam pointing of phased array radar by the pulse amplitude train, which is significant in radar electronic reconnaissance and electronic support measure. Firstly, the antenna patterns modeling of the phased array system is exploited to build the radar sweeping model and the signal propagation model. Secondly, the relationship between the variation of the radiated power and the antenna beam pointing angles in the given airspace is analyzed. Based on the above two points, the sample with obvious amplitude characteristics of the pulse amplitude train can be screened out after detecting the train peaks. Finally, the sample is matched to the subsequent pulse amplitude train based on the Hausdorff distance. The proposed methods have less prior knowledge and higher efficiency and are easier to process. By cross correlating the sample of the pulse amplitude train with the sample data of the antenna follow-up radiation, the probability of detection of the beam pointing direction becomes larger in case that the subsequent antenna beam returns to the specific position.
基金supported by the National Natural Science Foundation of China(Nos.11375195,11375263,and 11105143)the project of National Magnetic Confinement Fusion Energy Development Research(No.2013GB104003)
文摘A conventional multi-channel pulse amplitude analyzer acquires single energy spectrum,but provides no information on its tendency with time.To address the limitation,we propose a scheme of time-sharing multichannel pulse amplitude analyzer(TSMCA).A dual-port random access memory is divided into two storage spaces,one for current energy spectrum data acquisition and another for previous energy spectrum data storage.The two tasks can be performed simultaneously,and the time-related variation tendency of energy spectrum can be obtained.A prototype system of TSMCA is designed.It performs nicely,with maximum channel number of 4096 in capacity of 2^(32)/Ch,minimal time-sharing slice of 25 ms,the differential nonlinearity of <1.5%,and the integral nonlinearity of <0.3%.
文摘BACKGROUND Diabetes mellitus is a metabolic disorder characterized by prolonged elevation of blood glucose due to various causes.Currently,the relationship between diabetic retinopathy(DR)and altered connectivity of brain function is unclear.AIM To investigate the relationship between this brain activity and clinical manifestations and behaviors of DR patients by using the amplitude of low-frequency fluctuation(ALFF)technique.METHODS Twenty-four DR patients and 24 healthy controls(HCs)matched for age and gender were enrolled.We measured and recorded average ALFF values of DR patients and HCs and then classified them using receiver operating characteristic(ROC)curves.RESULTS ALFF values of both left and right posterior cerebellar lobe and right anterior cingulate gyrus were remarkably higher in the DR patients than in the HCs;however,DR patients had lower values in the bilateral calcarine area.ROC curve analysis of different brain regions demonstrated high accuracy in the area under the curve analysis.There was no significant relationship between mean ALFF values for different regions and clinical presentations in DR patients.Neuronal synchronization abnormalities in some brain regions of DR patients were associated with cognitive and visual disorders.CONCLUSION Abnormal spontaneous brain activity was observed in many areas of DR patients’brains,which may suggest a possible link between clinical manifestations and behaviors in DR patients.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304900 and 2017YFA0402300)the Beijing Natural Science Foundation(Grant No.1212014)+3 种基金the National Natural Science Foundation of China(Grant Nos.11604334,11604177,and U2031125)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB08-3)the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(Grant No.KF201807)the Fundamental Research Funds for the Central Universities,and Youth Innovation Promotion Association CAS.
文摘Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the presence of a local RF(LO RF)field.In this study,we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation(AM)of the LO RF field;that is,the phase of the SIG RF field is related to both the amplitude and phase of the beat signal.When the AM frequency of the LO RF field is the same as the frequency of the beat signal,the beat signal will further interfere with the AM of the LO RF field inside the atom,and then the amplitude of the beat signal is related to the phase of the SIG RF field.The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 toπ/2 when the phase of the AM is set with a differenceπ/4 from the phase of the LO RF field.The minimum phase resolution can be as small as 0.6°by optimizing the experimental conditions according to a simple theoretical model.This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.
基金This study was jointly funded by the National Natural Science Foundation of China(Grant Nos.41505042 and 41805041)the National Program on Global Change and Air−Sea Interaction(Grant No.GASI-IPOVAI-03)+1 种基金the National Basic Research Program of China(Grant Nos.2015CB953601 and 2014CB953903)the Fundamental Research Funds for the Central Universities.
文摘The variations in the wave energy and the amplitude along the energy dispersion paths of the barotropic Rossby waves in zonally symmetric basic flow are studied by solving the wave energy equation,which expresses that the wave energy variability is determined by the divergence of the group velocity and the energy budget from the basic flow.The results suggest that both the wave energy and the amplitude of a leading wave increase significantly in the propagating region that is located south of the jet axis and enclosed by a southern critical line and a northern turning latitude.The leading wave gains the barotropic energy from the basic flow by eddy activities.The amplitude continuously climbs up a peak at the turning latitude due to increasing wave energy and enlarging horizontal scale(shrinking total wavenumber).Both the wave energy and the amplitude eventually decrease when the trailing wave continuously approaches southward to the critical line.The trailing wave decays and its energy is continuously absorbed by the basic flow.Furthermore,both the wave energy and the amplitude oscillate with a limited range in the propagating region that is located near the jet axis and enclosed by two turning latitudes.Both the leading and trailing waves neither develop nor decay significantly.The jet works as a waveguide to allow the waves to propagate a long distance.
