In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as an...In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia.展开更多
This study endeavors to deal with the least square spectral analysis on the time series, to find present significant frequencies, to analyze 40 tide components using harmonic methods and to show relationship between d...This study endeavors to deal with the least square spectral analysis on the time series, to find present significant frequencies, to analyze 40 tide components using harmonic methods and to show relationship between discovered frequencies and 40 components of tide. For the purpose of collecting data of altimetry satellites of Topex/Poseidon (T/P), Jason 1, Jason 2 and coastal tide gauges of Bandar Anzali, Noshahr, and Nekah were utilized. In this time series formed by cross over points of altimetry satellite and then using least square spectral analysis on time series derived from altimetry satellite and coastal tide gauges the significant components were found and annual, biannual, and monthly components were discovered. Then, analysis of 40 tide components was conducted using harmonic method to find the amplitude and phase. It represented that solar annual (Sa) plays the most significant role on Caspian Sea corresponded to the least square spectral analysis of the time series. The results shows that the annual (Sa) and semi-annual Solar (Ssa) constituents on all of the ports listed have the highest amplitude in comparison with the other constituents which are respectively 16 cm, 18 cm and 15 cm for annual constituent and 2.8 cm, 5.4 cm and 3.7 cm for semi-annual constituent.展开更多
About 30 years of measurements made by the rain gauges located in Piedmont (Italy) have been analyzed. Rain gauges have been divided into 4 datasets considering the complex orography near Turin, namely the flatlands, ...About 30 years of measurements made by the rain gauges located in Piedmont (Italy) have been analyzed. Rain gauges have been divided into 4 datasets considering the complex orography near Turin, namely the flatlands, mountains, hills and urban areas. For each group of gauges, the Generalized Extreme Values (GEV) distributions are estimated considering both the entire dataset of available data and different sets of 3 years of data in running mode. It is shown that the GEV estimated parameters temporal series for the 3 years dataset do not present any specific trend over the entire period. The study presented here is preliminary to a future extreme rainfall event analysis using high temporal and spatial resolution X-band weather radar with a limited temporal availability of radar maps covering the same area.展开更多
1.Some definitions and notions 1.1. Hausdorff gauge and Packing gaugeA funciton h:[0.1]→ R is said to be a dimension function if it has the following properties:(1)h(t)is continuous and increasing, h(0)=0, h(t)>0 ...1.Some definitions and notions 1.1. Hausdorff gauge and Packing gaugeA funciton h:[0.1]→ R is said to be a dimension function if it has the following properties:(1)h(t)is continuous and increasing, h(0)=0, h(t)>0 when t>0.(2)there exists a constant M>0, h(2t)<Mh(t) for any t>0.展开更多
With permanent down-hole gauges （PDGs） widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of res...With permanent down-hole gauges （PDGs） widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of research interests in further developing pressure transient processing and analysis techniques. Transient pressure measurements from PDG are characterized by long term and high volume data. These data are recorded under unconstrained circumstances, so effects due to noise, rate fluctuation and interference from other wells cannot be avoided. These effects make the measured pressure trends decline or rise and then obscure or distort the actual flow behavior, which makes subsequent analysis difficult. In this paper, the problems encountered in analysis of PDG transient pressure are investigated. A newly developed workflow for processing and analyzing PDG transient pressure data is proposed. Numerical well testing synthetic studies are performed to demonstrate these procedures. The results prove that this new technique works well and the potential for practical application looks very promising.展开更多
In an effort to assess the reliability of satellite altimeter systems, the authors conduct a comparative analysis of sea level data that were collected from the TOPEX/POSEIDON (T/P) altimeter and 10 tide gauges (TG) n...In an effort to assess the reliability of satellite altimeter systems, the authors conduct a comparative analysis of sea level data that were collected from the TOPEX/POSEIDON (T/P) altimeter and 10 tide gauges (TG) near the satellite passing ground tracks. The analysis is made using datasets collected from marginal sea regions surrounding the Korean Peninsula at T/P cycles of 2 to 230, which correspond to October 1992 to December 1998. Proper treatment of tidal errors is a very critical step in data processing because the study area has very strong tide. When the T/P data are processed, the procedures of Park and Gamberoni (1995) are adapted to reduce errors associated with the tide. When the T/P data are processed in this way, the alias periods of M2, S2, and K1 constituents are found to be 62.1, 58.7, and 173 days repectively. The compatibility of the T/P and TG datasets are examined at various filtering periods. The results indicate that the low-frequency signals of the T/P data can be interpreted more safely with longer filtering periods (such as up to the maximum selected value of 200 days). When RMS errors for the 200-day low-pass filter period are compared with all 10 tidal stations, the values span the range of 2.8 to 6.7 cm. The results of a correlation analysis for this filtering period also show a strong agreement between the T/P and TG datasets across all stations investigated (e.g.,p- values consistently less than 0.001). Hence according to the analysis, the conclusion is made that the analysis of surface sea level using satellite altimeter data can be made safely with reasonably extended filtering periods such as 200 days.展开更多
Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are ...Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are enhanced when the two circularly polarized lights have comparable intensities.In addition,the curves of ionization rate versus the field amplitude ratio of the two colors for counter-rotating and co-rotating fields coincide with each other in the length gauge case at the total laser intensity 5×10^14 W/cm^2,which agrees with the experimental observation.Moreover,the degree of the coincidence between the ionization rate curves of the two bicircular fields decreases with the increasing field amplitude ratio and decreasing total laser intensity.With the help of the ADK theory,the above characteristics of the ionization rate curves can be well interpreted,which is related to the transition from the tunneling to multiphoton ionization mechanism.展开更多
The height changes of tide gauges directly influence sea level observation. For research of sea level variation in large region or globe, the land vertical displacement must be considered. Two sessions of GPS and abso...The height changes of tide gauges directly influence sea level observation. For research of sea level variation in large region or globe, the land vertical displacement must be considered. Two sessions of GPS and absolute gravity observations in 2001 and 2003 are used to determine the horizontal and vertical motion of China coast in ITRF2000 and Eurasia frame. The difference between results of continuous observation and periodic observation is discussed.展开更多
Single Alter shielded T-200BM3 weighing precipitation gauges are widely used in the measurement of all precipitation types(rainfall,snow and mixed precipitation)in unattended boreal or alpine regions,but their origina...Single Alter shielded T-200BM3 weighing precipitation gauges are widely used in the measurement of all precipitation types(rainfall,snow and mixed precipitation)in unattended boreal or alpine regions,but their original datasets must be adjusted for undercatch errors caused by wind in snowy,windy and harsh environments.Therefore,previous researchers have developed many adjustment methods for all precipitation types on different time scales.However,which adjustment method is suitable for T-200BM3 weighing gauge wind-induced error adjustment in harsh alpine regions is unclear.Therefore,precipitation measurement intercomparison experiments were conducted in the Qilian Mountains from July 2018 to July 2021,and eight adjustment methods;were evaluated for wind-induced errors for daily,individual precipitation event,hourly,and half-hourly time scales.Z2004 outperformed the other adjustment methods in regard to the daily measurements of snow and mixed precipitation.Regarding individual snowfall events,M2007 reduced the absolute value of RMSE(bias)from 1.44 to 1.32 mm(0.77-0.24 mm)and could be recommended for snowfall event adjustment.K2017-1 attained a better performance than K2017-2 in regard to half-hourly snowfall and mixed sample adjustment and was more suitable for half-hourly snowfall sample adjustment.K2017-1 reduced the absolute value of bias from 0.07 to 0.00 mm for snowfall.Finally,Z2004,M2007,and K2017-1 yielded better adjustment results for the daily accumulation precipitation amount(>2 mm d−1),individual snowfall events(>2 mm per event),and half-hourly accumulation snowfall or mixed samples(>1 mm 30 min−1),respectively.However,further intercomparison in different climate regions is needed for trace precipitation samples.展开更多
Precipitation data is vital fundamental data for climate change.However,obtaining precise gauge-measured precipitation in high-altitude mountains is challenging,and the precipitation obtained from various gauge types ...Precipitation data is vital fundamental data for climate change.However,obtaining precise gauge-measured precipitation in high-altitude mountains is challenging,and the precipitation obtained from various gauge types at the same station may vary.To understand the differences in precipitation observations among the three commonly used gauges in China(Chinese Standard Precipitation Gauges(CSPG),Total Rain weighing Sensor(TRwS),and Geonor T-200B(T200B))in high-altitude mountains and to recommend a stable and cost-effective weighing gauge,a precipitation intercomparison experiment was conducted at Hulu-1 station in the Qilian Mountains.The wind-induced error in measurement was corrected with the‘universal’transfer function recommended by the Word Meteorological Organization.The comparison results,adjusted for systematic errors,showed that the rain,snow and mixed precipitation of CSPG and TRwS equipped with the same octagonal vertical double fence shields(CSPGDF and TRwSDF)and single-Alter shields(CSPG_(s)and TRwSs)were close,while the precipitation of Tretyakov-shielded T200B was notably higher than that of CSPG_(s)and TRwSs.The average differences in annual and daily precipitation between CSPGDF and TRwSDF from 2017 to 2021 were 12.9 mm and 0.10 mm,respectively.The daily precipitation difference between CSPG_(s)and TRwSs from April 2019–December 2021 was 0.10 mm,while the differences between T200Bs and CSPG_(s)and TRwSs was 0.28 mm and 0.38 mm,respectively.The wind shield performance of Alter and Tretyakov was not much different at Hulu-1 site with low wind speed,thus the measurement principle of T200Bs was the primary cause of the high observations.Taking the corrected CSPGDF measurement as the standard,the dynamic loss of CSPG_(s)was 17.6%,while that of CSPGUn was 55.6%,indicating that the single-Alter shield could effectively reduce the impact of wind on precipitation measurement.Considering the comparison results and the price difference of the instruments,it was recommended to use a single-Alter shielded TRwS gauge for precipitation observation in high-altitude mountains.展开更多
Metal foil strain gauges remain the state-of-the-art transducers for wind tunnel balances.While strain gauge technology is very mature,piezoresistive semiconductor sensors offer alternatives that are worth exploring t...Metal foil strain gauges remain the state-of-the-art transducers for wind tunnel balances.While strain gauge technology is very mature,piezoresistive semiconductor sensors offer alternatives that are worth exploring to assess their unique benefits,such as better strain resolution and accuracy,which would enable balances to be designed with higher factors to safety and hence longer fatigue lifetimes.A new three-component balance,based on temperature compensated semiconductor strain gauges,is designed,calibrated and tested in a hypersonic low density wind tunnel.The static accuracy of the semiconductor balance is calibrated better than 0.3%FS,and the dynamic accuracy of the balance is established using a HB-2 standard model in a Mach 12 hypersonic flow.Good experimental repeatability is confirmed to be better than 2.5%FS,and the effectiveness of the balance is demonstrated by comparing the forces and moments of measured data with computational fluid dynamics simulations,as well as reference wind tunnel results under similar conditions.展开更多
The Global Precipitation Climatology Project （GPCP） monthly rainfall data and the rainfall records observed by 740 rain gauges in the mainland of China are used to analyze similarities and differences of the precipi...The Global Precipitation Climatology Project （GPCP） monthly rainfall data and the rainfall records observed by 740 rain gauges in the mainland of China are used to analyze similarities and differences of the precipitation in China in the period from January 1980 to December 2000. Results expose significantly consistent rainfall distributions between the both data in multi-year mean, multi-year seasonal mean, and multi-year monthly mean. Departures of monthly rainfall for each dataset also show a high correlation with an over 0.8 correlation coefficient. Analysis indicates small differences of both datasets during autumn, winter, and spring, but relative large ones in summer. Generally, the GPCP has trend of overestimating the rainfall rate. Based on above good relationship of both datasets, the GPCP data, are used to represent distributions and variations of precipitation in the Tibetan Plateau and Northwest China. Results indicate positive departures of precipitation in summer in the west part of Tibetan Plateau in the 1980s and negative departures after the 1980s. For the west part of Northwest China, analysis illustrates precipitation decreases a little, but no clear variation tendency.展开更多
Purpose-This paper aims to analyze the stress and strain distribution on the track wheel web surface and study the optimal strain gauge location for force measurement system of the track wheel.Design/methodology/appro...Purpose-This paper aims to analyze the stress and strain distribution on the track wheel web surface and study the optimal strain gauge location for force measurement system of the track wheel.Design/methodology/approach-Finite element method was employed to analyze the stress and strain distribution on the track wheel web surface under varying wheel-rail forces.Locations with minimal coupling interference between vertical and lateral forces were identified as suitable for strain gauge installation.Findings-The results show that due to the track wheel web’s unique curved shape and wheel-rail force loading mechanism,both tensile and compressive states exit on the surface of the web.When vertical force is applied,Mises stress and strain are relatively high near the inner radius of 710 mm and the outer radius of 1110mmof the web.Under lateral force,high Mises stress and strain are observed near the radius of 670mmon the inner and outer sides of the web.As the wheel-rail force application point shifts laterally toward the outer side,the Mises stress and strain near the inner radius of 710 mm of the web gradually decrease under vertical force while gradually increasing near the outer radius of 1110 mm of the web.Under lateral force,the Mises stress and strain on the surface of the web remain relatively unchanged regardless of the wheel-rail force application point.Based on the analysis of stress and strain on the surface of the web under different wheel-rail forces,the inner radius of 870 mm is recommended as the optimal mounting location of strain gauges for measuring vertical force,while the inner radius of 1143 mm is suitable for measuring lateral force.Originality/value-The research findings provide valuable insights for determining optimal strain gauge locations and designing an effective track wheel force measurement system.展开更多
We propose the new field potential by maintaining both the symmetry of the scalar gauge and the conservation law keeping N?ether’s theorem, while disregarding the symmetry of the vector gauge. The new potential forms...We propose the new field potential by maintaining both the symmetry of the scalar gauge and the conservation law keeping N?ether’s theorem, while disregarding the symmetry of the vector gauge. The new potential forms like the well-type potential where a particle behaves almost freely but is very hard to escape without external energy, which can be interpreted as local confinement and asymptotic freedom. By assuming a 2-dimensional metric tensor in 4-dimensional space-time, we suggest the existence of 3 kinds of particles that resemble QCD with 3 color charges. We also show that the mass term exists but comes to zero and derive the charge and spin values. We can regard the particle with this new potential as a gluon, and the interaction in this well-type potential as a strong interaction for the properties of mass, charge, spin, and its behavior. We suggest the eight-fold way with this new particle, which is similar to the existing method based on SU (3) symmetry. Even though the strong interaction has been analyzed in the standard model and string theory, we build a new consistent model based on the theory of relativity including Riemann geometry, and show the unification of gravitational and strong interactional field.展开更多
As the eventful year of 2023 drew to a close,China’s decisive economic rebound over the preceding 11 months continued to propel steady recovery of the flagging global economy.Last November,China’s retail sales of co...As the eventful year of 2023 drew to a close,China’s decisive economic rebound over the preceding 11 months continued to propel steady recovery of the flagging global economy.Last November,China’s retail sales of consumer goods-a major gauge of consumption strength-maintained accelerated growth,evident in a registered year-on-year increase of 10.1 percent,according to National Bureau of Statistics(NBS)data published on December 15.During the January-November period,moreover,total retail sales of the country’s consumer goods swelled to RMB 42.79 trillion-a 7.2 percent increase over the previous year.展开更多
Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transform...Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transformation does not correspond to a one-dimensional unitary group transformation U(1) of the wave function for the quantum case. In addition, with the re-examination of the relation between the magnetic field B and its vector potential A, we found that, in order to have a consistent formulation of the dynamics of the charged particle with both expressions, we must have that B=∇×A if and only if B≠0.展开更多
This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and i...This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and in the quantum regime a full renormalizable quantum gauge field theory. The three fundamental constraints (hamiltonian, gaussian and diffeomorphism) were formulated in 3-dimensional spatial form within LQG in Ashtekar formulation using the notion of the Kodama state with positive cosmological constant Λ. We introduce a 4-dimensional covariant version of the 3-dimensional (spatial) hamiltonian, gaussian and diffeomorphism constraints of LQG. We obtain 32 partial differential equations for the 16 variables E<sub>mn</sub> (E-tensor, inverse densitized tetrad of the metric) and 16 variables A<sub>mn</sub> (A-tensor, gravitational wave tensor). We impose the boundary condition: for large distance the E-generated metric g(E) becomes the GR-metric g (normally Schwarzschild-spacetime). The theory based on these Ashtekar-Kodama (AK) equations, and called in the following Ashtekar-Kodama (AK-) gravity has the following properties. • For Λ = 0 the AK equations become Einstein equations, A-tensor is trivial (constant), and the E-generated metric g(E) is identical with the GR-metric g. • When the AK-equations are developed into a Λ-power series, the Λ-term yields a gravitational wave equation, which has only at least quadrupole wave solutions and becomes in the limit of large distance r the (normal electromagnetic) wave equation. • AK-gravity, as opposed to GR, has no singularity at the horizon: the singularity in the metric becomes a (very high) peak. • AK-gravity has a limit scale of the gravitational quantum region 39 μm, which emerges as the limit scale in the objective wave collapse theory of Gherardi-Rimini-Weber. In the quantum region, the AK-gravity becomes a quantum gauge theory (AK quantum gravity) with the Lie group extended SU(2) = ε-tensor-group(four generators) as gauge group and a corresponding covariant derivative. • AK quantum gravity is fully renormalizable, we derive its Lagrangian, which is dimensionally renormalizable, the normalized one-graviton wave function, the graviton propagator, and demonstrate the calculation of cross-section from Feynman diagrams.展开更多
Let E be a cookie-cutter set with dimH E =s. It is known that the Hausdorff s-measure and the packing s-measure of the set E are positive and finite. In this paper, we prove that for a gauge function g the set E has p...Let E be a cookie-cutter set with dimH E =s. It is known that the Hausdorff s-measure and the packing s-measure of the set E are positive and finite. In this paper, we prove that for a gauge function g the set E has positive and finite Hausdorff g-measure if and only if 0 〈 liminft→0 g（t）/ts 〈 ∞. Also, we prove that for a doubling gauge function g the set E has positive and finite packing g-measure if and only if 0 〈 lim supt→0 g（t）/ts 〈 ∞.展开更多
Since 2008 a network of five sea-level monitoring stations was progressively installed in French Polynesia.The stations are autonomous and data,collected at a sampling rate of 1 or 2 min,are not only recorded locally,...Since 2008 a network of five sea-level monitoring stations was progressively installed in French Polynesia.The stations are autonomous and data,collected at a sampling rate of 1 or 2 min,are not only recorded locally,but also transferred in real time by a radio-link to the NOAA through the GOES satellite.The new ET34-ANA-V80 version of ETERNA,initially developed for Earth Tides analysis,is now able to analyze ocean tides records.Through a two-step validation scheme,we took advantage of the flexibility of this new version,operated in conjunction with the preprocessing facilities of the Tsoft software,to recover co rrected data series able to model sea-level variations after elimination of the ocean tides signal.We performed the tidal analysis of the tide gauge data with the highest possible selectivity(optimal wave grouping)and a maximum of additional terms(shallow water constituents).Our goal was to provide corrected data series and modelled ocean tides signal to compute tide-free sea-level variations as well as tidal prediction models with centimeter precision.We also present in this study the characteristics of the ocean tides in French Polynesia and preliminary results concerning the non-tidal variations of the sea level concerning the tide gauge setting.展开更多
基金the University of French Polynesiafunding by several successive“Decision Aide a la Recherche”(DAR)grants to the Geodesy Observatory of Tahiti from the French Space Agency(CNES)+2 种基金fundings from the local government of French Polynesia(Observatoire Polynesien du Rechauffement Climatique)funding by“National Natural Science Foundation of China”(Grand No.41931075)funding by“the Fundamental Research Funds for the Central Universities"(Grand No.2042022kf1198)。
文摘In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia.
文摘This study endeavors to deal with the least square spectral analysis on the time series, to find present significant frequencies, to analyze 40 tide components using harmonic methods and to show relationship between discovered frequencies and 40 components of tide. For the purpose of collecting data of altimetry satellites of Topex/Poseidon (T/P), Jason 1, Jason 2 and coastal tide gauges of Bandar Anzali, Noshahr, and Nekah were utilized. In this time series formed by cross over points of altimetry satellite and then using least square spectral analysis on time series derived from altimetry satellite and coastal tide gauges the significant components were found and annual, biannual, and monthly components were discovered. Then, analysis of 40 tide components was conducted using harmonic method to find the amplitude and phase. It represented that solar annual (Sa) plays the most significant role on Caspian Sea corresponded to the least square spectral analysis of the time series. The results shows that the annual (Sa) and semi-annual Solar (Ssa) constituents on all of the ports listed have the highest amplitude in comparison with the other constituents which are respectively 16 cm, 18 cm and 15 cm for annual constituent and 2.8 cm, 5.4 cm and 3.7 cm for semi-annual constituent.
文摘About 30 years of measurements made by the rain gauges located in Piedmont (Italy) have been analyzed. Rain gauges have been divided into 4 datasets considering the complex orography near Turin, namely the flatlands, mountains, hills and urban areas. For each group of gauges, the Generalized Extreme Values (GEV) distributions are estimated considering both the entire dataset of available data and different sets of 3 years of data in running mode. It is shown that the GEV estimated parameters temporal series for the 3 years dataset do not present any specific trend over the entire period. The study presented here is preliminary to a future extreme rainfall event analysis using high temporal and spatial resolution X-band weather radar with a limited temporal availability of radar maps covering the same area.
文摘1.Some definitions and notions 1.1. Hausdorff gauge and Packing gaugeA funciton h:[0.1]→ R is said to be a dimension function if it has the following properties:(1)h(t)is continuous and increasing, h(0)=0, h(t)>0 when t>0.(2)there exists a constant M>0, h(2t)<Mh(t) for any t>0.
基金Science Foundation of China University of Petroleum, Beijing (No.YJRC-2011-02)for the financial support during this research
文摘With permanent down-hole gauges （PDGs） widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of research interests in further developing pressure transient processing and analysis techniques. Transient pressure measurements from PDG are characterized by long term and high volume data. These data are recorded under unconstrained circumstances, so effects due to noise, rate fluctuation and interference from other wells cannot be avoided. These effects make the measured pressure trends decline or rise and then obscure or distort the actual flow behavior, which makes subsequent analysis difficult. In this paper, the problems encountered in analysis of PDG transient pressure are investigated. A newly developed workflow for processing and analyzing PDG transient pressure data is proposed. Numerical well testing synthetic studies are performed to demonstrate these procedures. The results prove that this new technique works well and the potential for practical application looks very promising.
文摘In an effort to assess the reliability of satellite altimeter systems, the authors conduct a comparative analysis of sea level data that were collected from the TOPEX/POSEIDON (T/P) altimeter and 10 tide gauges (TG) near the satellite passing ground tracks. The analysis is made using datasets collected from marginal sea regions surrounding the Korean Peninsula at T/P cycles of 2 to 230, which correspond to October 1992 to December 1998. Proper treatment of tidal errors is a very critical step in data processing because the study area has very strong tide. When the T/P data are processed, the procedures of Park and Gamberoni (1995) are adapted to reduce errors associated with the tide. When the T/P data are processed in this way, the alias periods of M2, S2, and K1 constituents are found to be 62.1, 58.7, and 173 days repectively. The compatibility of the T/P and TG datasets are examined at various filtering periods. The results indicate that the low-frequency signals of the T/P data can be interpreted more safely with longer filtering periods (such as up to the maximum selected value of 200 days). When RMS errors for the 200-day low-pass filter period are compared with all 10 tidal stations, the values span the range of 2.8 to 6.7 cm. The results of a correlation analysis for this filtering period also show a strong agreement between the T/P and TG datasets across all stations investigated (e.g.,p- values consistently less than 0.001). Hence according to the analysis, the conclusion is made that the analysis of surface sea level using satellite altimeter data can be made safely with reasonably extended filtering periods such as 200 days.
基金Project supported by the Key Laboratory Project of Computational Physics of National Defense Science and Technology of China(Grant No.6142A05180401)the National Key Program for S&T Research and Development of China(Grant Nos.2019YFA0307700 and 2016YFA0401100)the National Natural Science Foundation of China(Grant Nos.11847307,11425414,11504215,11774361,and 11874246).
文摘Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are enhanced when the two circularly polarized lights have comparable intensities.In addition,the curves of ionization rate versus the field amplitude ratio of the two colors for counter-rotating and co-rotating fields coincide with each other in the length gauge case at the total laser intensity 5×10^14 W/cm^2,which agrees with the experimental observation.Moreover,the degree of the coincidence between the ionization rate curves of the two bicircular fields decreases with the increasing field amplitude ratio and decreasing total laser intensity.With the help of the ADK theory,the above characteristics of the ionization rate curves can be well interpreted,which is related to the transition from the tunneling to multiphoton ionization mechanism.
文摘The height changes of tide gauges directly influence sea level observation. For research of sea level variation in large region or globe, the land vertical displacement must be considered. Two sessions of GPS and absolute gravity observations in 2001 and 2003 are used to determine the horizontal and vertical motion of China coast in ITRF2000 and Eurasia frame. The difference between results of continuous observation and periodic observation is discussed.
基金funded by the National Natural Sciences Foundation of China(42101120,42171145,41971041)Natural Science Foundation of Shandong Province,China(ZR2021QD138).
文摘Single Alter shielded T-200BM3 weighing precipitation gauges are widely used in the measurement of all precipitation types(rainfall,snow and mixed precipitation)in unattended boreal or alpine regions,but their original datasets must be adjusted for undercatch errors caused by wind in snowy,windy and harsh environments.Therefore,previous researchers have developed many adjustment methods for all precipitation types on different time scales.However,which adjustment method is suitable for T-200BM3 weighing gauge wind-induced error adjustment in harsh alpine regions is unclear.Therefore,precipitation measurement intercomparison experiments were conducted in the Qilian Mountains from July 2018 to July 2021,and eight adjustment methods;were evaluated for wind-induced errors for daily,individual precipitation event,hourly,and half-hourly time scales.Z2004 outperformed the other adjustment methods in regard to the daily measurements of snow and mixed precipitation.Regarding individual snowfall events,M2007 reduced the absolute value of RMSE(bias)from 1.44 to 1.32 mm(0.77-0.24 mm)and could be recommended for snowfall event adjustment.K2017-1 attained a better performance than K2017-2 in regard to half-hourly snowfall and mixed sample adjustment and was more suitable for half-hourly snowfall sample adjustment.K2017-1 reduced the absolute value of bias from 0.07 to 0.00 mm for snowfall.Finally,Z2004,M2007,and K2017-1 yielded better adjustment results for the daily accumulation precipitation amount(>2 mm d−1),individual snowfall events(>2 mm per event),and half-hourly accumulation snowfall or mixed samples(>1 mm 30 min−1),respectively.However,further intercomparison in different climate regions is needed for trace precipitation samples.
基金This study was funded by the National Natural Sciences Foundation of China(42101120,42171145,41971041)the Joint Research Project of Three-River Headwaters National Park,Chinese Academy of Sciences and the People's Government of Qinghai Province(LHZX-2020-11)the Gansu Natural Science Foundation(22JR5RA071).
文摘Precipitation data is vital fundamental data for climate change.However,obtaining precise gauge-measured precipitation in high-altitude mountains is challenging,and the precipitation obtained from various gauge types at the same station may vary.To understand the differences in precipitation observations among the three commonly used gauges in China(Chinese Standard Precipitation Gauges(CSPG),Total Rain weighing Sensor(TRwS),and Geonor T-200B(T200B))in high-altitude mountains and to recommend a stable and cost-effective weighing gauge,a precipitation intercomparison experiment was conducted at Hulu-1 station in the Qilian Mountains.The wind-induced error in measurement was corrected with the‘universal’transfer function recommended by the Word Meteorological Organization.The comparison results,adjusted for systematic errors,showed that the rain,snow and mixed precipitation of CSPG and TRwS equipped with the same octagonal vertical double fence shields(CSPGDF and TRwSDF)and single-Alter shields(CSPG_(s)and TRwSs)were close,while the precipitation of Tretyakov-shielded T200B was notably higher than that of CSPG_(s)and TRwSs.The average differences in annual and daily precipitation between CSPGDF and TRwSDF from 2017 to 2021 were 12.9 mm and 0.10 mm,respectively.The daily precipitation difference between CSPG_(s)and TRwSs from April 2019–December 2021 was 0.10 mm,while the differences between T200Bs and CSPG_(s)and TRwSs was 0.28 mm and 0.38 mm,respectively.The wind shield performance of Alter and Tretyakov was not much different at Hulu-1 site with low wind speed,thus the measurement principle of T200Bs was the primary cause of the high observations.Taking the corrected CSPGDF measurement as the standard,the dynamic loss of CSPG_(s)was 17.6%,while that of CSPGUn was 55.6%,indicating that the single-Alter shield could effectively reduce the impact of wind on precipitation measurement.Considering the comparison results and the price difference of the instruments,it was recommended to use a single-Alter shielded TRwS gauge for precipitation observation in high-altitude mountains.
文摘Metal foil strain gauges remain the state-of-the-art transducers for wind tunnel balances.While strain gauge technology is very mature,piezoresistive semiconductor sensors offer alternatives that are worth exploring to assess their unique benefits,such as better strain resolution and accuracy,which would enable balances to be designed with higher factors to safety and hence longer fatigue lifetimes.A new three-component balance,based on temperature compensated semiconductor strain gauges,is designed,calibrated and tested in a hypersonic low density wind tunnel.The static accuracy of the semiconductor balance is calibrated better than 0.3%FS,and the dynamic accuracy of the balance is established using a HB-2 standard model in a Mach 12 hypersonic flow.Good experimental repeatability is confirmed to be better than 2.5%FS,and the effectiveness of the balance is demonstrated by comparing the forces and moments of measured data with computational fluid dynamics simulations,as well as reference wind tunnel results under similar conditions.
基金Supported by Grants of NKBRDPC (No.2004CB418304),NSFC grant of the Joint Research Fund for Overseas Chinese Young Scholars (No.40428006),NSFC (Nos.40175015 and 40375018).
文摘The Global Precipitation Climatology Project （GPCP） monthly rainfall data and the rainfall records observed by 740 rain gauges in the mainland of China are used to analyze similarities and differences of the precipitation in China in the period from January 1980 to December 2000. Results expose significantly consistent rainfall distributions between the both data in multi-year mean, multi-year seasonal mean, and multi-year monthly mean. Departures of monthly rainfall for each dataset also show a high correlation with an over 0.8 correlation coefficient. Analysis indicates small differences of both datasets during autumn, winter, and spring, but relative large ones in summer. Generally, the GPCP has trend of overestimating the rainfall rate. Based on above good relationship of both datasets, the GPCP data, are used to represent distributions and variations of precipitation in the Tibetan Plateau and Northwest China. Results indicate positive departures of precipitation in summer in the west part of Tibetan Plateau in the 1980s and negative departures after the 1980s. For the west part of Northwest China, analysis illustrates precipitation decreases a little, but no clear variation tendency.
基金funded by the Fund Project of China Academy of Railway Sciences Corporation Limited[Grant No.2022YJ194,2023YJ254].
文摘Purpose-This paper aims to analyze the stress and strain distribution on the track wheel web surface and study the optimal strain gauge location for force measurement system of the track wheel.Design/methodology/approach-Finite element method was employed to analyze the stress and strain distribution on the track wheel web surface under varying wheel-rail forces.Locations with minimal coupling interference between vertical and lateral forces were identified as suitable for strain gauge installation.Findings-The results show that due to the track wheel web’s unique curved shape and wheel-rail force loading mechanism,both tensile and compressive states exit on the surface of the web.When vertical force is applied,Mises stress and strain are relatively high near the inner radius of 710 mm and the outer radius of 1110mmof the web.Under lateral force,high Mises stress and strain are observed near the radius of 670mmon the inner and outer sides of the web.As the wheel-rail force application point shifts laterally toward the outer side,the Mises stress and strain near the inner radius of 710 mm of the web gradually decrease under vertical force while gradually increasing near the outer radius of 1110 mm of the web.Under lateral force,the Mises stress and strain on the surface of the web remain relatively unchanged regardless of the wheel-rail force application point.Based on the analysis of stress and strain on the surface of the web under different wheel-rail forces,the inner radius of 870 mm is recommended as the optimal mounting location of strain gauges for measuring vertical force,while the inner radius of 1143 mm is suitable for measuring lateral force.Originality/value-The research findings provide valuable insights for determining optimal strain gauge locations and designing an effective track wheel force measurement system.
文摘We propose the new field potential by maintaining both the symmetry of the scalar gauge and the conservation law keeping N?ether’s theorem, while disregarding the symmetry of the vector gauge. The new potential forms like the well-type potential where a particle behaves almost freely but is very hard to escape without external energy, which can be interpreted as local confinement and asymptotic freedom. By assuming a 2-dimensional metric tensor in 4-dimensional space-time, we suggest the existence of 3 kinds of particles that resemble QCD with 3 color charges. We also show that the mass term exists but comes to zero and derive the charge and spin values. We can regard the particle with this new potential as a gluon, and the interaction in this well-type potential as a strong interaction for the properties of mass, charge, spin, and its behavior. We suggest the eight-fold way with this new particle, which is similar to the existing method based on SU (3) symmetry. Even though the strong interaction has been analyzed in the standard model and string theory, we build a new consistent model based on the theory of relativity including Riemann geometry, and show the unification of gravitational and strong interactional field.
文摘As the eventful year of 2023 drew to a close,China’s decisive economic rebound over the preceding 11 months continued to propel steady recovery of the flagging global economy.Last November,China’s retail sales of consumer goods-a major gauge of consumption strength-maintained accelerated growth,evident in a registered year-on-year increase of 10.1 percent,according to National Bureau of Statistics(NBS)data published on December 15.During the January-November period,moreover,total retail sales of the country’s consumer goods swelled to RMB 42.79 trillion-a 7.2 percent increase over the previous year.
文摘Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transformation does not correspond to a one-dimensional unitary group transformation U(1) of the wave function for the quantum case. In addition, with the re-examination of the relation between the magnetic field B and its vector potential A, we found that, in order to have a consistent formulation of the dynamics of the charged particle with both expressions, we must have that B=∇×A if and only if B≠0.
文摘This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and in the quantum regime a full renormalizable quantum gauge field theory. The three fundamental constraints (hamiltonian, gaussian and diffeomorphism) were formulated in 3-dimensional spatial form within LQG in Ashtekar formulation using the notion of the Kodama state with positive cosmological constant Λ. We introduce a 4-dimensional covariant version of the 3-dimensional (spatial) hamiltonian, gaussian and diffeomorphism constraints of LQG. We obtain 32 partial differential equations for the 16 variables E<sub>mn</sub> (E-tensor, inverse densitized tetrad of the metric) and 16 variables A<sub>mn</sub> (A-tensor, gravitational wave tensor). We impose the boundary condition: for large distance the E-generated metric g(E) becomes the GR-metric g (normally Schwarzschild-spacetime). The theory based on these Ashtekar-Kodama (AK) equations, and called in the following Ashtekar-Kodama (AK-) gravity has the following properties. • For Λ = 0 the AK equations become Einstein equations, A-tensor is trivial (constant), and the E-generated metric g(E) is identical with the GR-metric g. • When the AK-equations are developed into a Λ-power series, the Λ-term yields a gravitational wave equation, which has only at least quadrupole wave solutions and becomes in the limit of large distance r the (normal electromagnetic) wave equation. • AK-gravity, as opposed to GR, has no singularity at the horizon: the singularity in the metric becomes a (very high) peak. • AK-gravity has a limit scale of the gravitational quantum region 39 μm, which emerges as the limit scale in the objective wave collapse theory of Gherardi-Rimini-Weber. In the quantum region, the AK-gravity becomes a quantum gauge theory (AK quantum gravity) with the Lie group extended SU(2) = ε-tensor-group(four generators) as gauge group and a corresponding covariant derivative. • AK quantum gravity is fully renormalizable, we derive its Lagrangian, which is dimensionally renormalizable, the normalized one-graviton wave function, the graviton propagator, and demonstrate the calculation of cross-section from Feynman diagrams.
基金Supported by NSFC (Grant Nos.10571063,10771164)HuBei JiaoYuTing (Grant No.D20061001)
文摘Let E be a cookie-cutter set with dimH E =s. It is known that the Hausdorff s-measure and the packing s-measure of the set E are positive and finite. In this paper, we prove that for a gauge function g the set E has positive and finite Hausdorff g-measure if and only if 0 〈 liminft→0 g（t）/ts 〈 ∞. Also, we prove that for a doubling gauge function g the set E has positive and finite packing g-measure if and only if 0 〈 lim supt→0 g（t）/ts 〈 ∞.
基金funding from the“Talent Introduction Scientific Research Start-Up Fund”of Shandong University of Science and Technology(Grant number 0104060510217)the“Open Fund of State Key Laboratory of Geodesy and Earth’s Dynamics”(Grant number SKLGED2021-3-5)。
文摘Since 2008 a network of five sea-level monitoring stations was progressively installed in French Polynesia.The stations are autonomous and data,collected at a sampling rate of 1 or 2 min,are not only recorded locally,but also transferred in real time by a radio-link to the NOAA through the GOES satellite.The new ET34-ANA-V80 version of ETERNA,initially developed for Earth Tides analysis,is now able to analyze ocean tides records.Through a two-step validation scheme,we took advantage of the flexibility of this new version,operated in conjunction with the preprocessing facilities of the Tsoft software,to recover co rrected data series able to model sea-level variations after elimination of the ocean tides signal.We performed the tidal analysis of the tide gauge data with the highest possible selectivity(optimal wave grouping)and a maximum of additional terms(shallow water constituents).Our goal was to provide corrected data series and modelled ocean tides signal to compute tide-free sea-level variations as well as tidal prediction models with centimeter precision.We also present in this study the characteristics of the ocean tides in French Polynesia and preliminary results concerning the non-tidal variations of the sea level concerning the tide gauge setting.
