Purpose – Straightness measurement of rail weld joint is of essential importance to railway maintenance. Dueto the lack of efficient measurement equipment, there has been limited in-depth research on rail weld joint ...Purpose – Straightness measurement of rail weld joint is of essential importance to railway maintenance. Dueto the lack of efficient measurement equipment, there has been limited in-depth research on rail weld joint with a5-m wavelength range, leaving a significant knowledge gap in this field.Design/methodology/approach – In this study, the authors used the well-established inertial referencemethod (IR-method), and the state-of-the-art multi-point chord reference method (MCR-method). Two methodshave been applied in different types of rail straightness measurement trollies, respectively. These instrumentswere tested in a high-speed rail section within a certain region of China. The test results were ultimatelyvalidated through using traditional straightedge and feeler gauge methods as reference data to evaluate the railweld joint straightness within the 5-m wavelength range.Findings – The research reveals that IR-method and MCR-method produce reasonably similar measurementresults for wavelengths below 1 m. However, MCR-method outperforms IR-method in terms of accuracy forwavelengths exceeding 3 m. Furthermore, it was observed that IR-method, while operating at a slower speed,carries the risk of derailing and is incapable of detecting rail weld joints and low joints within the track.Originality/value – The research compare two methods’ measurement effects in a longer wavelength rangeand demonstrate the superiority of MCR-method.展开更多
Based on the meteorological data from 1951 to 2015 in Beijing,the reference crop evapotranspiration(ET_0)in Beijing was estimated using the FAO 56 Penman-Monteith method,the FAO PPP-17 Penman method,the Hargreaves met...Based on the meteorological data from 1951 to 2015 in Beijing,the reference crop evapotranspiration(ET_0)in Beijing was estimated using the FAO 56 Penman-Monteith method,the FAO PPP-17 Penman method,the Hargreaves method,and the Priestley-Taylor method.The results showed that the monthly and annual changing trends of ET0 estimated by the four methods are basically the same.In general,the ET0 values estimated by the Hargreaves method are the closest to those of the standard method FAO 56 Penman-Monteith,while the difference between the FAO PPP-17 Penman method and the standard method is the biggest.The Hargreaves method is the most suitable method for the estimation of ET0 in Beijing.展开更多
Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material reali...Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material realization of the ITRS defined in IERS Conventions. The main input includes the time series of weekly solutions （or fortnightly for SLR 1983-1993） of observational data for satellite techniques and session-wise normal equations for VLBI. The set of estimated unknowns includes 3- dimensional Cartesian coordinates at the reference epoch 2005.0 of the stations distributed globally and their rates as well as the time series of consistent Earth Orientation Parameters （EOPs） at the same epochs as the input. Besides the final solution, namely SOL-2, generated by using all the inputs before 2015.0 obtained from short-term observation processing, another reference solution, namely SOL- 1, was also computed by using the input before 2009.0 based on the same combination of procedures for the purpose of comparison with ITRF2008 and DTRF2008 and for evaluating the effect of the latest six more years of data on the combined results. The estimated accuracy of the x-component and y-component of the SOL- 1 TRF-origin was better than 0.1 mm at epoch 2005.0 and better than 0.3 mm yr- 1 in time evolution, either compared with ITRF2008 or DTRF2008. However, the z-component of the translation parameters from SOL-1 to ITRF2008 and DTRF2008 were 3.4 mm and -1.0 ram, respectively. It seems that the z-component of the SOL-1 TRF-origin was much closer to the one in DTRF2008 than the one in ITRF2008. The translation parameters from SOL-2 to ITRF2014 were 2.2, -1.8 and 0.9 mm in the x-, y- and z-components respectively with rates smaller than 0.4 mmyr-1. Similarly, the scale factor transformed from SOL-1 to DTRF2008 was much smaller than that to ITRF2008. The scale parameter from SOL-2 to ITRF2014 was -0.31 ppb with a rate lower than 0.01 ppb yr-1. The external precision （WRMS） compared with IERS EOP 08 C04 of the combined EOP series was smaller than 0.06 mas for the polar motions, smaller than 0.01 ms for the UT1-UTC and smaller than 0.02 ms for the LODs. The precision of the EOPs in SOL-2 was slightly higher than that of SOL-1.展开更多
A novel fiber Bragg grating （FBG） sensor array system based on digital phase generated carrier （PGC） demodulation and reference compensation method is proposed and set up. Experimental results confirm that the dig...A novel fiber Bragg grating （FBG） sensor array system based on digital phase generated carrier （PGC） demodulation and reference compensation method is proposed and set up. Experimental results confirm that the digital PGC demodulation can be used for wavelength-division-multiplexed FBG sensor array and the reference compensation method can reduce the environmental interference by approximately 40 dB in the frequency range from 20 Hz to 2 kHz. The minimum detectable wavelength-shift of the sensor system is 1 × 10^-3 pm/Hz^1/2.展开更多
Reference crop evapotranspiration (ET_0) is a critical part in water cycle and water balance of ecosystem, which is greatly important to effective utilization of agricultural water resources and for making reasonable ...Reference crop evapotranspiration (ET_0) is a critical part in water cycle and water balance of ecosystem, which is greatly important to effective utilization of agricultural water resources and for making reasonable irrigation system. In order to propose a suitable method for computing ET_0 in North Xinjiang, based on daily meteorological data from May 1 to September30, 2010 provided by Weather Station of Fuhai County, we used FAO56 Penman-Monteith as the standard formula to compute ET_0, compared the differences and relations between such the method and other 4 calculation formulas, and analyzed the cause of the deviation, finally evaluated the applicability of computational method in North Xinjiang. The results showed that the calculation results by FA056 PM Method was approximate to that by FAO Penman method and IA method, of which the relative error was 9.26% and 13.51% respectively, the ET_0 results calculated by PT method and HS method were generally greater than the results by FAO56 PM, and their deviation was very obvious.展开更多
Eleven recently completed toxicological studies were critically reviewed to identify toxicologically significant endpoints and dose-response information. Dose-response data were compiled and entered into the USEPA＇s ...Eleven recently completed toxicological studies were critically reviewed to identify toxicologically significant endpoints and dose-response information. Dose-response data were compiled and entered into the USEPA＇s benchmark dose software （BMDS） for calculation of a benchmark dose （BMD） and a benchmark dose low （BMDL）. After assessing 91 endpoints across the nine studies, a total of 23 of these endpoints were identified for BMD modeling, and BMDL estimates corresponding to various dose-response models were compiled for these separate endpoints. Thyroid, neurobehavior and reproductive endpoints for BDE-47, -99, -209 were quantitatively evaluated. According to methods and feature of each study, different uncertainty factor （UF） value was decided and subsequently reference doses （RfDs） were proposed. Consistent with USEPA, the lowest BMDLs of 2.10, 81.77, and 1698 I^g/kg were used to develop RfDs for BDE-47, -99, and -209, respectively. RfDs for BDE-99 and BDE-209 were comparable to EPA results, and however, RfD of BDE-47 was much lower than that of EPA, which may result from that reproductive/developmental proves to be more sensitive than neurobehavior for BDE-47 and the principal study uses very-low-dose exposure.展开更多
The Hartree-Fock equation is non-linear and has, in principle, multiple solutions. The ωth HF extreme and its associated virtual spin-orbitals furnish an orthogonal base Bω of the full configuration interaction spac...The Hartree-Fock equation is non-linear and has, in principle, multiple solutions. The ωth HF extreme and its associated virtual spin-orbitals furnish an orthogonal base Bω of the full configuration interaction space. Although all Bω bases generate the same CI space, the corresponding configurations of each Bω base have distinct quantum-mechanical information contents. In previous works, we have introduced a multi-reference configuration interaction method, based on the multiple extremes of the Hartree-Fock problem. This method was applied to calculate the permanent electrical dipole and quadrupole moments of some small molecules using minimal and double, triple and polarized double-zeta bases. In all cases were possible, using a reduced number of configurations, to obtain dipole and quadrupole moments in close agreement with the experimental values and energies without compromising the energy of the state function. These results show the positive effect of the use of the multi-reference Hartree-Fock bases that allowed a better extraction of quantum mechanical information from the several Bω bases. But to extend these ideas for larger systems and atomic bases, it is necessary to develop criteria to build the multireference Hartree-Fock bases. In this project, we are beginning a study of the non-uniform distribution of quantum-mechanical information content of the Bω bases, searching identify the factors that allowed obtain the good results cited展开更多
This study deals with temporal trends in the Penman-Monteith reference evapotranspiration estimated from standard meteorological observations, observed pan evaporation, and four related meteorological variables during...This study deals with temporal trends in the Penman-Monteith reference evapotranspiration estimated from standard meteorological observations, observed pan evaporation, and four related meteorological variables during 1970-2000 in the Yangtze River catchment. Relative contributions of the four meteorological variables to changes in the reference evapotranspiration are quantified. The results show that both the reference evapotranspiration and the pan evaporation have significant decreasing trends in the upper, the middle as well as in the whole Changjiang （Yangtze） River catchment at the 5% significance level, while the air temperature shows a significant increasing trend. The decreasing trend detected in the reference evapotranspiration can be attributed to the significant decreasing trends in the net radiation and the wind speed.展开更多
In this paper, an analogue correction method of errors （ACE） based on a complicated atmospheric model is further developed and applied to numerical weather prediction （NWP）. The analysis shows that the ACE can eff...In this paper, an analogue correction method of errors （ACE） based on a complicated atmospheric model is further developed and applied to numerical weather prediction （NWP）. The analysis shows that the ACE can effectively reduce model errors by combining the statistical analogue method with the dynamical model together in order that the information of plenty of historical data is utilized in the current complicated NWP model, Furthermore, in the ACE, the differences of the similarities between different historical analogues and the current initial state are considered as the weights for estimating model errors. The results of daily, decad and monthly prediction experiments on a complicated T63 atmospheric model show that the performance of the ACE by correcting model errors based on the estimation of the errors of 4 historical analogue predictions is not only better than that of the scheme of only introducing the correction of the errors of every single analogue prediction, but is also better than that of the T63 model.展开更多
A method is developed to calculate probability of collision. Based on geometric features of space objects during the encounter, it is reasonable to separate the radial orbital motions from those in the cross section f...A method is developed to calculate probability of collision. Based on geometric features of space objects during the encounter, it is reasonable to separate the radial orbital motions from those in the cross section for most encounter events that occur in a near-circular orbit. Therefore, the probability of collision caused by differences in both altitude of the orbit in the radial direction and the probability of collision caused by differences in arrival time in the cross section are calculated. The net probability of collision is expressed as an explicit expression by multiplying the above two components. Numerical cases are applied to test this method by comparing the results with the general method. The results indicate that this method is valid for most encounter events that occur in near-circular orbits.展开更多
Considering the importance of reference evapotranspiration (RET) in agriculture, hydrology and meteorology, the research problem was taken to assess the RET during winter season under projected climatic situation of W...Considering the importance of reference evapotranspiration (RET) in agriculture, hydrology and meteorology, the research problem was taken to assess the RET during winter season under projected climatic situation of West Bengal, India. The Penman-Monteith method was used in the study as it is the most accurate method of estimating RET. However, validation of the output of the equation was done with the help of observed data set. The data analysis was carried out using NCAR Command Language (NCL). The result clearly shows that the reference ET of the study area will be increased in the tune of 13% to 32% in the year 2050 compared to present RET level. Analysis of actual rainfall data shows a decreasing trend of winter rainfall in the study region. The projected rainfall data also follows the same pattern. Thus, the combination of low rainfall and higher ET value will demand more irrigation requirement for winter crops in West Bengal. The temporal changes of RET on decadal basis and spatial variation of RET for each decade have been observed and discussed in the paper.展开更多
Salvianolic acid A(Sal A),a water-soluble ingredient in Danshen,has various biological activities.Sal A and its impurities have similar physical and chemical properties,as well as strong reducibility;therefore,they ar...Salvianolic acid A(Sal A),a water-soluble ingredient in Danshen,has various biological activities.Sal A and its impurities have similar physical and chemical properties,as well as strong reducibility;therefore,they are difficult to prepare and purify.In this study,high-purity Sal A was obtained by purification of sephadex chromatography and preparative chromatography.Furthermore,HPLC-DAD tandem ECD and HPLC-DAD tandem MS methods were used for non-volatile organic impurity analysis,ICP-MS method was used for non-volatile inorganic impurities and mass balance method and quantitative nuclear magnetic resonance were employed to certify the product.The structures of Sal A and its relative impurities were validated by nuclear magnetic resonance spectroscopy and mass spectrometry,and their contents were quantified as well.Following the principles of ISO Guides 34:2009 and 35:2005,a Sal A reference material was certified,covering homogeneity studies,stability studies,characterization,and uncertainty estimations.展开更多
Considering that there is no single full reference image quality assessment method that could give the best performance in all situations, some multi-method fusion metrics were proposed. Machine learning techniques ar...Considering that there is no single full reference image quality assessment method that could give the best performance in all situations, some multi-method fusion metrics were proposed. Machine learning techniques are often involved in such multi-method fusion metrics so that its output would be more consistent with human visual perceptions. On the other hand, the robustness and generalization ability of these multi-method fusion metrics are questioned because of the scarce of images with mean opinion scores. In order to comprehensively validate whether or not the generalization ability of such multi-method fusion IQA metrics are satisfying, we construct a new image database which contains up to 60 reference images. The newly built image database is then used to test the generalization ability of different multi-method fusion IQA metrics. Cross database validation experiment indicates that in our new image database, the performances of all the multi-method fusion IQA metrics have no statistical significant different with some single-method IQA metrics such as FSIM and MAD. In the end, a thorough analysis is given to explain why the performance of multi-method fusion IQA framework drop significantly in cross database validation.展开更多
The fast slewing rate and wide band of the VLBI2010 Global Observing System(VGOS) telescopes are beneficial to procure more observations and to obtain VLBI reference points(RPs) of high precisions.Meanwhile, with the ...The fast slewing rate and wide band of the VLBI2010 Global Observing System(VGOS) telescopes are beneficial to procure more observations and to obtain VLBI reference points(RPs) of high precisions.Meanwhile, with the development of synchronous tracking of fixed targets on telescopes during the observing, the RPs also can be determined in near real time based on a frame defined by other techniques. These opportunities provide us a possibility to explore the high geodetic resolution of VGOS telescopes. We design a thermal variation in RP as true values, and schedule a synchronous session of VGOS and target point(TP) series observing. Then VGOS delays and TP series are simulated and solved via piecewise functions. The results show that the accuracy of vertical component of the RP could be determined at an accuracy of 0.5 ± 0.3 mm in an hour using TP series, whereas the vertical components of RP solved by using VGOS delay measurements have a greater uncertainty due to the random error in the simulated atmosphere and bad radio source sky coverage in a shorter time interval. Some details in the data processing and accuracy evaluation are also introduced.展开更多
In this paper, the integration methods of dynamics equations of relative motion of variable mass nonlinear nonholonomic system are given such as the gradient method, the single-component method and the field method. F...In this paper, the integration methods of dynamics equations of relative motion of variable mass nonlinear nonholonomic system are given such as the gradient method, the single-component method and the field method. Firstly, the dynamics equations are written in the canonical form and the field form. Secondly, the gradient method, the single-component method and the field method are used to integrate the dynamics equations of the corresponding constant mass holonomic system in inertial reference frame respectively. With the restriction of nonholonomic constraints to the initial conditions being considered, the solutions of the dynamics equations of variable mass nonlinear nonholonomic system in noninertial reference frame are obtained.展开更多
This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then ...This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then obtains differential equations of motion of variable mass nonholonomic nonconservative system in noninertial reference frame.展开更多
Considering the fact that the results of laboratory tests provide useful information about the state of health of patients, determination of reference value is considered an intrinsic part in the development of labora...Considering the fact that the results of laboratory tests provide useful information about the state of health of patients, determination of reference value is considered an intrinsic part in the development of laboratory medi-cine. There are still huge differences in the analytical methods used as well as in the associated reference intervals which could consequently significantly affect the proper assessment of patient health. In a constant effort to increase the quality of patients' care, there are numerous international initiatives for standardiza-tion and/or harmonization of laboratory diagnostics in order to achieve maximum comparability of laboratory test results and improve patient safety. Through the standardization and harmonization processes of analytical methods the ability to create unique reference intervals is achieved. Such reference intervals could be applied globally in all laboratories using methods traceable to the same reference measuring system and analysing the biological samples from the populations with similar socio-demographic and ethnic characteristics. In this review we outlined the results of the harmonization processes in Croatia in the field of population based reference intervals for clinically relevant blood and serum constituents which are in accordance with ongoing activity for worldwide standardization and harmonization based on traceability in laboratory medicine.展开更多
This paper first analyzes the features of two classes of numerical methods for global analysis of nonlinear dynamical systems, which regard state space respectively as continuous and discrete ones. On basis of this un...This paper first analyzes the features of two classes of numerical methods for global analysis of nonlinear dynamical systems, which regard state space respectively as continuous and discrete ones. On basis of this understanding it then points out that the previously proposed method of point mapping under cell reference (PMUCR), has laid a frame work for the development of a two scaled numerical method suitable for the global analysis of high dimensional nonlinear systems, which may take the advantages of both classes of single scaled methods but will release the difficulties induced by the disadvantages of them. The basic ideas and main steps of implementation of the two scaled method, namely extended PMUCR, are elaborated. Finally, two examples are presented to demonstrate the capabilities of the proposed method.展开更多
文摘Purpose – Straightness measurement of rail weld joint is of essential importance to railway maintenance. Dueto the lack of efficient measurement equipment, there has been limited in-depth research on rail weld joint with a5-m wavelength range, leaving a significant knowledge gap in this field.Design/methodology/approach – In this study, the authors used the well-established inertial referencemethod (IR-method), and the state-of-the-art multi-point chord reference method (MCR-method). Two methodshave been applied in different types of rail straightness measurement trollies, respectively. These instrumentswere tested in a high-speed rail section within a certain region of China. The test results were ultimatelyvalidated through using traditional straightedge and feeler gauge methods as reference data to evaluate the railweld joint straightness within the 5-m wavelength range.Findings – The research reveals that IR-method and MCR-method produce reasonably similar measurementresults for wavelengths below 1 m. However, MCR-method outperforms IR-method in terms of accuracy forwavelengths exceeding 3 m. Furthermore, it was observed that IR-method, while operating at a slower speed,carries the risk of derailing and is incapable of detecting rail weld joints and low joints within the track.Originality/value – The research compare two methods’ measurement effects in a longer wavelength rangeand demonstrate the superiority of MCR-method.
基金Supported by National Natural Science Foundation of China(41371065)
文摘Based on the meteorological data from 1951 to 2015 in Beijing,the reference crop evapotranspiration(ET_0)in Beijing was estimated using the FAO 56 Penman-Monteith method,the FAO PPP-17 Penman method,the Hargreaves method,and the Priestley-Taylor method.The results showed that the monthly and annual changing trends of ET0 estimated by the four methods are basically the same.In general,the ET0 values estimated by the Hargreaves method are the closest to those of the standard method FAO 56 Penman-Monteith,while the difference between the FAO PPP-17 Penman method and the standard method is the biggest.The Hargreaves method is the most suitable method for the estimation of ET0 in Beijing.
基金supported by the Ministry of Science and Technology of China(2015FY310200)the National Key Research and Development Program of China(2016YFB0501405)+1 种基金the National Natural Science Foundation of China(11173048 and 11403076)the State Key Laboratory of Aerospace Dynamics and the Crustal Movement Observation Network of China(CMONOC)
文摘Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material realization of the ITRS defined in IERS Conventions. The main input includes the time series of weekly solutions （or fortnightly for SLR 1983-1993） of observational data for satellite techniques and session-wise normal equations for VLBI. The set of estimated unknowns includes 3- dimensional Cartesian coordinates at the reference epoch 2005.0 of the stations distributed globally and their rates as well as the time series of consistent Earth Orientation Parameters （EOPs） at the same epochs as the input. Besides the final solution, namely SOL-2, generated by using all the inputs before 2015.0 obtained from short-term observation processing, another reference solution, namely SOL- 1, was also computed by using the input before 2009.0 based on the same combination of procedures for the purpose of comparison with ITRF2008 and DTRF2008 and for evaluating the effect of the latest six more years of data on the combined results. The estimated accuracy of the x-component and y-component of the SOL- 1 TRF-origin was better than 0.1 mm at epoch 2005.0 and better than 0.3 mm yr- 1 in time evolution, either compared with ITRF2008 or DTRF2008. However, the z-component of the translation parameters from SOL-1 to ITRF2008 and DTRF2008 were 3.4 mm and -1.0 ram, respectively. It seems that the z-component of the SOL-1 TRF-origin was much closer to the one in DTRF2008 than the one in ITRF2008. The translation parameters from SOL-2 to ITRF2014 were 2.2, -1.8 and 0.9 mm in the x-, y- and z-components respectively with rates smaller than 0.4 mmyr-1. Similarly, the scale factor transformed from SOL-1 to DTRF2008 was much smaller than that to ITRF2008. The scale parameter from SOL-2 to ITRF2014 was -0.31 ppb with a rate lower than 0.01 ppb yr-1. The external precision （WRMS） compared with IERS EOP 08 C04 of the combined EOP series was smaller than 0.06 mas for the polar motions, smaller than 0.01 ms for the UT1-UTC and smaller than 0.02 ms for the LODs. The precision of the EOPs in SOL-2 was slightly higher than that of SOL-1.
基金supported by the National 863 Program under Grant No. 2007AA03Z415.
文摘A novel fiber Bragg grating （FBG） sensor array system based on digital phase generated carrier （PGC） demodulation and reference compensation method is proposed and set up. Experimental results confirm that the digital PGC demodulation can be used for wavelength-division-multiplexed FBG sensor array and the reference compensation method can reduce the environmental interference by approximately 40 dB in the frequency range from 20 Hz to 2 kHz. The minimum detectable wavelength-shift of the sensor system is 1 × 10^-3 pm/Hz^1/2.
基金Supported by Key Scientific and Technological Research and Development Program of Xinjiang(201531115)Special Fund for Scientific Research of China Institute of Water Resources and Hydropower Research(MK2016J10)
文摘Reference crop evapotranspiration (ET_0) is a critical part in water cycle and water balance of ecosystem, which is greatly important to effective utilization of agricultural water resources and for making reasonable irrigation system. In order to propose a suitable method for computing ET_0 in North Xinjiang, based on daily meteorological data from May 1 to September30, 2010 provided by Weather Station of Fuhai County, we used FAO56 Penman-Monteith as the standard formula to compute ET_0, compared the differences and relations between such the method and other 4 calculation formulas, and analyzed the cause of the deviation, finally evaluated the applicability of computational method in North Xinjiang. The results showed that the calculation results by FA056 PM Method was approximate to that by FAO Penman method and IA method, of which the relative error was 9.26% and 13.51% respectively, the ET_0 results calculated by PT method and HS method were generally greater than the results by FAO56 PM, and their deviation was very obvious.
基金financially supported by the Natural Science Foundation of China(Grant 81072263,to Y.Z.)Chun Tsung Scholarship of Fudan University(to D.C.)
文摘Eleven recently completed toxicological studies were critically reviewed to identify toxicologically significant endpoints and dose-response information. Dose-response data were compiled and entered into the USEPA＇s benchmark dose software （BMDS） for calculation of a benchmark dose （BMD） and a benchmark dose low （BMDL）. After assessing 91 endpoints across the nine studies, a total of 23 of these endpoints were identified for BMD modeling, and BMDL estimates corresponding to various dose-response models were compiled for these separate endpoints. Thyroid, neurobehavior and reproductive endpoints for BDE-47, -99, -209 were quantitatively evaluated. According to methods and feature of each study, different uncertainty factor （UF） value was decided and subsequently reference doses （RfDs） were proposed. Consistent with USEPA, the lowest BMDLs of 2.10, 81.77, and 1698 I^g/kg were used to develop RfDs for BDE-47, -99, and -209, respectively. RfDs for BDE-99 and BDE-209 were comparable to EPA results, and however, RfD of BDE-47 was much lower than that of EPA, which may result from that reproductive/developmental proves to be more sensitive than neurobehavior for BDE-47 and the principal study uses very-low-dose exposure.
文摘The Hartree-Fock equation is non-linear and has, in principle, multiple solutions. The ωth HF extreme and its associated virtual spin-orbitals furnish an orthogonal base Bω of the full configuration interaction space. Although all Bω bases generate the same CI space, the corresponding configurations of each Bω base have distinct quantum-mechanical information contents. In previous works, we have introduced a multi-reference configuration interaction method, based on the multiple extremes of the Hartree-Fock problem. This method was applied to calculate the permanent electrical dipole and quadrupole moments of some small molecules using minimal and double, triple and polarized double-zeta bases. In all cases were possible, using a reduced number of configurations, to obtain dipole and quadrupole moments in close agreement with the experimental values and energies without compromising the energy of the state function. These results show the positive effect of the use of the multi-reference Hartree-Fock bases that allowed a better extraction of quantum mechanical information from the several Bω bases. But to extend these ideas for larger systems and atomic bases, it is necessary to develop criteria to build the multireference Hartree-Fock bases. In this project, we are beginning a study of the non-uniform distribution of quantum-mechanical information content of the Bω bases, searching identify the factors that allowed obtain the good results cited
文摘This study deals with temporal trends in the Penman-Monteith reference evapotranspiration estimated from standard meteorological observations, observed pan evaporation, and four related meteorological variables during 1970-2000 in the Yangtze River catchment. Relative contributions of the four meteorological variables to changes in the reference evapotranspiration are quantified. The results show that both the reference evapotranspiration and the pan evaporation have significant decreasing trends in the upper, the middle as well as in the whole Changjiang （Yangtze） River catchment at the 5% significance level, while the air temperature shows a significant increasing trend. The decreasing trend detected in the reference evapotranspiration can be attributed to the significant decreasing trends in the net radiation and the wind speed.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 40575036 and 40325015）.Acknowledgement The authors thank Drs Zhang Pei-Qun and Bao Ming very much for their valuable comments on the present paper.
文摘In this paper, an analogue correction method of errors （ACE） based on a complicated atmospheric model is further developed and applied to numerical weather prediction （NWP）. The analysis shows that the ACE can effectively reduce model errors by combining the statistical analogue method with the dynamical model together in order that the information of plenty of historical data is utilized in the current complicated NWP model, Furthermore, in the ACE, the differences of the similarities between different historical analogues and the current initial state are considered as the weights for estimating model errors. The results of daily, decad and monthly prediction experiments on a complicated T63 atmospheric model show that the performance of the ACE by correcting model errors based on the estimation of the errors of 4 historical analogue predictions is not only better than that of the scheme of only introducing the correction of the errors of every single analogue prediction, but is also better than that of the T63 model.
基金Supported by the National Natural Science Foundation of China
文摘A method is developed to calculate probability of collision. Based on geometric features of space objects during the encounter, it is reasonable to separate the radial orbital motions from those in the cross section for most encounter events that occur in a near-circular orbit. Therefore, the probability of collision caused by differences in both altitude of the orbit in the radial direction and the probability of collision caused by differences in arrival time in the cross section are calculated. The net probability of collision is expressed as an explicit expression by multiplying the above two components. Numerical cases are applied to test this method by comparing the results with the general method. The results indicate that this method is valid for most encounter events that occur in near-circular orbits.
文摘Considering the importance of reference evapotranspiration (RET) in agriculture, hydrology and meteorology, the research problem was taken to assess the RET during winter season under projected climatic situation of West Bengal, India. The Penman-Monteith method was used in the study as it is the most accurate method of estimating RET. However, validation of the output of the equation was done with the help of observed data set. The data analysis was carried out using NCAR Command Language (NCL). The result clearly shows that the reference ET of the study area will be increased in the tune of 13% to 32% in the year 2050 compared to present RET level. Analysis of actual rainfall data shows a decreasing trend of winter rainfall in the study region. The projected rainfall data also follows the same pattern. Thus, the combination of low rainfall and higher ET value will demand more irrigation requirement for winter crops in West Bengal. The temporal changes of RET on decadal basis and spatial variation of RET for each decade have been observed and discussed in the paper.
基金The authors acknowledge National Key R&D Program of China(Grant No.2016YFC1000900)The Drug Innovation Major Project(Grant No.2018ZX09711001-001-015)should be substituted by Drug Innovation Major Project(Grant No.2018ZX09711001-003-022)CAMS Innovation Fund for Medical Sciences(Grant No.2016-I2M-3-007)for financing this work.
文摘Salvianolic acid A(Sal A),a water-soluble ingredient in Danshen,has various biological activities.Sal A and its impurities have similar physical and chemical properties,as well as strong reducibility;therefore,they are difficult to prepare and purify.In this study,high-purity Sal A was obtained by purification of sephadex chromatography and preparative chromatography.Furthermore,HPLC-DAD tandem ECD and HPLC-DAD tandem MS methods were used for non-volatile organic impurity analysis,ICP-MS method was used for non-volatile inorganic impurities and mass balance method and quantitative nuclear magnetic resonance were employed to certify the product.The structures of Sal A and its relative impurities were validated by nuclear magnetic resonance spectroscopy and mass spectrometry,and their contents were quantified as well.Following the principles of ISO Guides 34:2009 and 35:2005,a Sal A reference material was certified,covering homogeneity studies,stability studies,characterization,and uncertainty estimations.
基金supported by “the Fundamental Research Funds for the Central Universities” No.2018CUCTJ081
文摘Considering that there is no single full reference image quality assessment method that could give the best performance in all situations, some multi-method fusion metrics were proposed. Machine learning techniques are often involved in such multi-method fusion metrics so that its output would be more consistent with human visual perceptions. On the other hand, the robustness and generalization ability of these multi-method fusion metrics are questioned because of the scarce of images with mean opinion scores. In order to comprehensively validate whether or not the generalization ability of such multi-method fusion IQA metrics are satisfying, we construct a new image database which contains up to 60 reference images. The newly built image database is then used to test the generalization ability of different multi-method fusion IQA metrics. Cross database validation experiment indicates that in our new image database, the performances of all the multi-method fusion IQA metrics have no statistical significant different with some single-method IQA metrics such as FSIM and MAD. In the end, a thorough analysis is given to explain why the performance of multi-method fusion IQA framework drop significantly in cross database validation.
基金supported by National Natural Science Foundation of China (1703067)
文摘The fast slewing rate and wide band of the VLBI2010 Global Observing System(VGOS) telescopes are beneficial to procure more observations and to obtain VLBI reference points(RPs) of high precisions.Meanwhile, with the development of synchronous tracking of fixed targets on telescopes during the observing, the RPs also can be determined in near real time based on a frame defined by other techniques. These opportunities provide us a possibility to explore the high geodetic resolution of VGOS telescopes. We design a thermal variation in RP as true values, and schedule a synchronous session of VGOS and target point(TP) series observing. Then VGOS delays and TP series are simulated and solved via piecewise functions. The results show that the accuracy of vertical component of the RP could be determined at an accuracy of 0.5 ± 0.3 mm in an hour using TP series, whereas the vertical components of RP solved by using VGOS delay measurements have a greater uncertainty due to the random error in the simulated atmosphere and bad radio source sky coverage in a shorter time interval. Some details in the data processing and accuracy evaluation are also introduced.
文摘In this paper, the integration methods of dynamics equations of relative motion of variable mass nonlinear nonholonomic system are given such as the gradient method, the single-component method and the field method. Firstly, the dynamics equations are written in the canonical form and the field form. Secondly, the gradient method, the single-component method and the field method are used to integrate the dynamics equations of the corresponding constant mass holonomic system in inertial reference frame respectively. With the restriction of nonholonomic constraints to the initial conditions being considered, the solutions of the dynamics equations of variable mass nonlinear nonholonomic system in noninertial reference frame are obtained.
文摘This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then obtains differential equations of motion of variable mass nonholonomic nonconservative system in noninertial reference frame.
基金Supported by The Ministry of science and technology,Zagreb,Croatia,No.55.3-01-143
文摘Considering the fact that the results of laboratory tests provide useful information about the state of health of patients, determination of reference value is considered an intrinsic part in the development of laboratory medi-cine. There are still huge differences in the analytical methods used as well as in the associated reference intervals which could consequently significantly affect the proper assessment of patient health. In a constant effort to increase the quality of patients' care, there are numerous international initiatives for standardiza-tion and/or harmonization of laboratory diagnostics in order to achieve maximum comparability of laboratory test results and improve patient safety. Through the standardization and harmonization processes of analytical methods the ability to create unique reference intervals is achieved. Such reference intervals could be applied globally in all laboratories using methods traceable to the same reference measuring system and analysing the biological samples from the populations with similar socio-demographic and ethnic characteristics. In this review we outlined the results of the harmonization processes in Croatia in the field of population based reference intervals for clinically relevant blood and serum constituents which are in accordance with ongoing activity for worldwide standardization and harmonization based on traceability in laboratory medicine.
基金supported by the National Natural Science Foundation of China (NSFC) (10872155)
文摘This paper first analyzes the features of two classes of numerical methods for global analysis of nonlinear dynamical systems, which regard state space respectively as continuous and discrete ones. On basis of this understanding it then points out that the previously proposed method of point mapping under cell reference (PMUCR), has laid a frame work for the development of a two scaled numerical method suitable for the global analysis of high dimensional nonlinear systems, which may take the advantages of both classes of single scaled methods but will release the difficulties induced by the disadvantages of them. The basic ideas and main steps of implementation of the two scaled method, namely extended PMUCR, are elaborated. Finally, two examples are presented to demonstrate the capabilities of the proposed method.
