The frequency band between 5 010 MHz and 5 030 MHz allocated as C band has been used as a candidate in the global navigation satellite systems(GNSS)along with more and more navigation services in L band.The potential ...The frequency band between 5 010 MHz and 5 030 MHz allocated as C band has been used as a candidate in the global navigation satellite systems(GNSS)along with more and more navigation services in L band.The potential benefits and technical requirements of C band for satellite navigation have been analyzed before.However the degradation of effective carrier-power-to-noise density ratio(Δ(C/N0)eff)based on code tracking spectral sensitivity coefficient(CT_SSC)as a compatibility assessment methodology for potential GNSS radio frequency compatibility in C-Band has not been discussed clearly.So the compatibility of the signals in the C band between BeiDou(BD)B1Cand GPS L1 C,L1C/A,Galileo E1 Os as the interoperability or classical signals in L band is analyzed.Simulation results reveal the interference degree between BD III B1 Cand GPS L1C/A,L1 C,Galileo E1 OS.The results can also reveal that the multiplexed binary offset carrier(MBOC)and binary phase shift keying(BPSK)modulation is not appropriate for C band.展开更多
The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive in...The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.展开更多
Within the framework of building energy assessment,this article proposes to use a derivative based sensitivity analysis of heat transfer models in a building envelope.Two,global and local,estimators are obtained at lo...Within the framework of building energy assessment,this article proposes to use a derivative based sensitivity analysis of heat transfer models in a building envelope.Two,global and local,estimators are obtained at low computational cost,to evaluate the influence of the parameters on the model outputs.Ranking of these estimators values allows to reduce the number of model unknown parameters by excluding non-significant parameters.A comparison with variance and regression-based methods is carried out and the results highlight the satisfactory accuracy of the continuous-based approach.Moreover,for the carried investigations the approach is 100 times faster compared to the variance-based methods.A case study applies the method to a real-world building wall.The sensitivity of the thermal loads to local or global variations of the wall thermal properties is investigated.Additionally,a case study of wall with window is analyzed.展开更多
基金Supported by the National High Technology Research and Development Program of China(863Program)(2011AA120502)
文摘The frequency band between 5 010 MHz and 5 030 MHz allocated as C band has been used as a candidate in the global navigation satellite systems(GNSS)along with more and more navigation services in L band.The potential benefits and technical requirements of C band for satellite navigation have been analyzed before.However the degradation of effective carrier-power-to-noise density ratio(Δ(C/N0)eff)based on code tracking spectral sensitivity coefficient(CT_SSC)as a compatibility assessment methodology for potential GNSS radio frequency compatibility in C-Band has not been discussed clearly.So the compatibility of the signals in the C band between BeiDou(BD)B1Cand GPS L1 C,L1C/A,Galileo E1 Os as the interoperability or classical signals in L band is analyzed.Simulation results reveal the interference degree between BD III B1 Cand GPS L1C/A,L1 C,Galileo E1 OS.The results can also reveal that the multiplexed binary offset carrier(MBOC)and binary phase shift keying(BPSK)modulation is not appropriate for C band.
文摘The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.
文摘Within the framework of building energy assessment,this article proposes to use a derivative based sensitivity analysis of heat transfer models in a building envelope.Two,global and local,estimators are obtained at low computational cost,to evaluate the influence of the parameters on the model outputs.Ranking of these estimators values allows to reduce the number of model unknown parameters by excluding non-significant parameters.A comparison with variance and regression-based methods is carried out and the results highlight the satisfactory accuracy of the continuous-based approach.Moreover,for the carried investigations the approach is 100 times faster compared to the variance-based methods.A case study applies the method to a real-world building wall.The sensitivity of the thermal loads to local or global variations of the wall thermal properties is investigated.Additionally,a case study of wall with window is analyzed.
