Nowadays, most positioning systems carry out locational calculation based on the accurate location information of some devices in the network. However there is a deviation in the locational information of the part of ...Nowadays, most positioning systems carry out locational calculation based on the accurate location information of some devices in the network. However there is a deviation in the locational information of the part of the device, we need to reduce it in order to obtain higher positioning accuracy. In this paper, we proposed a new centralized D2D(Device-to-Device) co-location algorithm. This algorithm uses DBSACN(Density-Based Spatial Clustering of Applications with Noise) clustering to reduce the deviation of device location information. Numerical results show that the positioning accuracy of the centralized D2D co-localization algorithm is improved by 62.7% compared with the SPAWN algorithm, which positioning performance superior to the traditional co-localization algorithm.展开更多
An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides(p-QMs)and aza-para-quinone methides(aza-p-QMs)with H-phosphorus oxides via dehydration/1,6-addit...An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides(p-QMs)and aza-para-quinone methides(aza-p-QMs)with H-phosphorus oxides via dehydration/1,6-addition under ultrasonic irradiation is described.This methodology provides a rapid and green approach for the construction of diarylmethyl phosphorus oxides bearing phosphorus-substituted quaternary carbon centers in high yields(up to 98%yield)within merely 5min.This environmentally benign protocol represents a unique example of 1,6-conjugate additions of propargylic p-QMs and aza-p-QMs for site-selective C-P bond formation in an operationally simple and atom-economical manner.The use of readily available Brønsted acid catalyst,operationally simplicity,high yields,and high atom economy make this protocol very facile,practical,easily scaled-up and environmentally friendly.展开更多
To make a rapid comfort assessment and a reasonable dynamic parameters choice of wheelchair robots,this paper proposes a dynamic comfort coefficientκand analytically optimizes the cushion damping.Firstly,a traveling ...To make a rapid comfort assessment and a reasonable dynamic parameters choice of wheelchair robots,this paper proposes a dynamic comfort coefficientκand analytically optimizes the cushion damping.Firstly,a traveling vibration model of the occupantwheelchair system for wheelchair robots running on random roads was created.Secondly,the analytic formula of the occupant RMS(root mean square)acceleration was deduced.Moreover,the dynamic coefficientκwas proposed and its influence laws were revealed.Finally,the cushion system optimal damping ratio was calculated based onκ.The results show that theκvalue is only determined by the parameters of the occupant-wheelchair system.The smaller theκvalue is,the better the dynamic comfort is for wheelchair robots running on random roads.By minimizingκ,the occupant-wheelchair system can achieve a statistically optimal dynamic comfort effect.展开更多
基金financially supported by the National Key Research&Development Program under Grant No.2018YFC0809702。
文摘Nowadays, most positioning systems carry out locational calculation based on the accurate location information of some devices in the network. However there is a deviation in the locational information of the part of the device, we need to reduce it in order to obtain higher positioning accuracy. In this paper, we proposed a new centralized D2D(Device-to-Device) co-location algorithm. This algorithm uses DBSACN(Density-Based Spatial Clustering of Applications with Noise) clustering to reduce the deviation of device location information. Numerical results show that the positioning accuracy of the centralized D2D co-localization algorithm is improved by 62.7% compared with the SPAWN algorithm, which positioning performance superior to the traditional co-localization algorithm.
基金We are grateful for financial support from the National Natural Science Foundation of China(No.21762005)Natural Science Foundation of Guangxi Province(No.2021GXNSFDA075005).
文摘An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides(p-QMs)and aza-para-quinone methides(aza-p-QMs)with H-phosphorus oxides via dehydration/1,6-addition under ultrasonic irradiation is described.This methodology provides a rapid and green approach for the construction of diarylmethyl phosphorus oxides bearing phosphorus-substituted quaternary carbon centers in high yields(up to 98%yield)within merely 5min.This environmentally benign protocol represents a unique example of 1,6-conjugate additions of propargylic p-QMs and aza-p-QMs for site-selective C-P bond formation in an operationally simple and atom-economical manner.The use of readily available Brønsted acid catalyst,operationally simplicity,high yields,and high atom economy make this protocol very facile,practical,easily scaled-up and environmentally friendly.
基金the National Natural Science Foundation of China(51575325).
文摘To make a rapid comfort assessment and a reasonable dynamic parameters choice of wheelchair robots,this paper proposes a dynamic comfort coefficientκand analytically optimizes the cushion damping.Firstly,a traveling vibration model of the occupantwheelchair system for wheelchair robots running on random roads was created.Secondly,the analytic formula of the occupant RMS(root mean square)acceleration was deduced.Moreover,the dynamic coefficientκwas proposed and its influence laws were revealed.Finally,the cushion system optimal damping ratio was calculated based onκ.The results show that theκvalue is only determined by the parameters of the occupant-wheelchair system.The smaller theκvalue is,the better the dynamic comfort is for wheelchair robots running on random roads.By minimizingκ,the occupant-wheelchair system can achieve a statistically optimal dynamic comfort effect.