The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and freque...The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and frequency of the wireless signal between different receivers.Therefore,ground monitoring stations need to be equipped with more than two antenna receiving stations,and multiple satellites should be able to simultaneously relay the distress signal from the target source in order to achieve the geolocation function.However,when the ground receiving system has only one antenna receiving station,or the target source is in a heavily obscured environment,the ground side is unable to receive the forwarded signals from multiple satellites at the same time,which will make it impossible to locate.To address these problems,in this paper,a time-sharing single satellite geolocations method based on different orbits is proposed for the first time.This method uses one or several low-earth orbit satellites(LEO)and mediumearth orbit satellites(MEO)in the visible area,and the receiving station only needs one pair of receiving antennas to complete the positioning.It can effectively compensate for the shortcomings of the traditional TDOA using the same moment and have better positioning accuracy compared with the single satellite in the same orbit.Due to the limited experimental conditions,this paper tests the navigation satellite using different orbit time-sharing single satellite geolocations,and proves that the positioning method has high positioning accuracy and has certain promotion and application value.展开更多
This paper discusses the “Hubble constant measurement—mystery”. Independent measurements of this cosmic parameter, referred to as <i><span style="font-family:Verdana;">H</span></i>...This paper discusses the “Hubble constant measurement—mystery”. Independent measurements of this cosmic parameter, referred to as <i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">0</span></sub><span style="font-family:Verdana;"> in abbreviated form, have all led to different values, with the highest value ≈ 74 km<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>s</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>Mpc</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> and the lowest ≈ 67 km<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>s</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>Mpc</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">, where km denotes kilometer, s second and Mpc</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> megaparsec. These measurements have mainly been obtained with space telescopes. Apparently, up to now there was no way to explain the differences. However, previously published studies seem to regard the problem of the different measurement results for </span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">0</span></sub><span style="font-family:Verdana;"> [</span><span style="font-family:Verdana;"><a href="#ref1">1</a>,</span><b><span style="font-family:Verdana;"> </span></b><span style="font-family:Verdana;"><a href="#ref2">2</a></span><span style="font-family:Verdana;">]. I have shown that due to a symmetrical expansion of the Minkowski space (SMS), each respective frame of reference for an observer, who rests in the zero point of the frame, is converted into a state of apparent rest relative to the cosmic microwave background (CMB) radiation. This SMS-relativistic effect also seems to be responsible for the different measurement results of the Hubble constant, especially through space telescopes.</span>展开更多
The highest occupied molecular orbital(HOMO) energies of fullerenes are found by quantitative first-principles calculations to be raised by negative charging, and the rising rate rank of the fullerenes is C60 >C7...The highest occupied molecular orbital(HOMO) energies of fullerenes are found by quantitative first-principles calculations to be raised by negative charging, and the rising rate rank of the fullerenes is C60 >C70 >C80 >C90>C100 >C180. Then we compare fullerenes with carbon nanotubes(CNTs) and graphene sheets(GSs) and find that the increase of the HOMO energy of a fullerene is much faster than that of CNTs and graphene sheets with the same number of C atoms. The rising rate rank is fullerene>CNT>GS, which holds no matter what the number of C atoms is or which structure the fullerene isomer is. This work paves a new path for developing all-carbon devices with low-dimensional carbon nanomaterials as different functional elements.展开更多
基金supported by National Science Foundation of China(No.91738201,U21A20450)。
文摘The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and frequency of the wireless signal between different receivers.Therefore,ground monitoring stations need to be equipped with more than two antenna receiving stations,and multiple satellites should be able to simultaneously relay the distress signal from the target source in order to achieve the geolocation function.However,when the ground receiving system has only one antenna receiving station,or the target source is in a heavily obscured environment,the ground side is unable to receive the forwarded signals from multiple satellites at the same time,which will make it impossible to locate.To address these problems,in this paper,a time-sharing single satellite geolocations method based on different orbits is proposed for the first time.This method uses one or several low-earth orbit satellites(LEO)and mediumearth orbit satellites(MEO)in the visible area,and the receiving station only needs one pair of receiving antennas to complete the positioning.It can effectively compensate for the shortcomings of the traditional TDOA using the same moment and have better positioning accuracy compared with the single satellite in the same orbit.Due to the limited experimental conditions,this paper tests the navigation satellite using different orbit time-sharing single satellite geolocations,and proves that the positioning method has high positioning accuracy and has certain promotion and application value.
文摘This paper discusses the “Hubble constant measurement—mystery”. Independent measurements of this cosmic parameter, referred to as <i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">0</span></sub><span style="font-family:Verdana;"> in abbreviated form, have all led to different values, with the highest value ≈ 74 km<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>s</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>Mpc</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> and the lowest ≈ 67 km<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>s</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>Mpc</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">, where km denotes kilometer, s second and Mpc</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> megaparsec. These measurements have mainly been obtained with space telescopes. Apparently, up to now there was no way to explain the differences. However, previously published studies seem to regard the problem of the different measurement results for </span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">0</span></sub><span style="font-family:Verdana;"> [</span><span style="font-family:Verdana;"><a href="#ref1">1</a>,</span><b><span style="font-family:Verdana;"> </span></b><span style="font-family:Verdana;"><a href="#ref2">2</a></span><span style="font-family:Verdana;">]. I have shown that due to a symmetrical expansion of the Minkowski space (SMS), each respective frame of reference for an observer, who rests in the zero point of the frame, is converted into a state of apparent rest relative to the cosmic microwave background (CMB) radiation. This SMS-relativistic effect also seems to be responsible for the different measurement results of the Hubble constant, especially through space telescopes.</span>
基金Supported by the National Natural Science Foundation of China under Grant Nos 11374174,51390471,51527803,and 51701143the National Basic Research Program of China under Grant No 2015CB654902+4 种基金the National Key Research and Development Program under Grant No 2016YFB0700402the Foundation for the Author of National Excellent Doctoral Dissertation under Grant No 201141the National Program for Thousand Young Talents of China,the Tianjin Municipal Education Commissionthe Tianjin Municipal Science and Technology Commissionthe Fundamental Research Fund of Tianjin University of Technology
文摘The highest occupied molecular orbital(HOMO) energies of fullerenes are found by quantitative first-principles calculations to be raised by negative charging, and the rising rate rank of the fullerenes is C60 >C70 >C80 >C90>C100 >C180. Then we compare fullerenes with carbon nanotubes(CNTs) and graphene sheets(GSs) and find that the increase of the HOMO energy of a fullerene is much faster than that of CNTs and graphene sheets with the same number of C atoms. The rising rate rank is fullerene>CNT>GS, which holds no matter what the number of C atoms is or which structure the fullerene isomer is. This work paves a new path for developing all-carbon devices with low-dimensional carbon nanomaterials as different functional elements.