In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc...In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc networks is proposed.In this scheme, a sender can simultaneously signcrypt n messeges for n receivers, and a receiver can unsigncrypt the ciphertext to get his message with his own private key.An analysis of this scheme indicates that it achieves authenticity and confidentiality in the random oracle model while being of lower computation and communication overhead.Finally, for the application of our scheme in ad hoc, a threshold key updating protocol for ad hoc networks is given.展开更多
The machining principle and realization method for the continuous generative grinding face gear by a worm wheel are introduced. Based on a five-axis linked CNC grinding machine, a new method is presented to deprive th...The machining principle and realization method for the continuous generative grinding face gear by a worm wheel are introduced. Based on a five-axis linked CNC grinding machine, a new method is presented to deprive the equation of face gear error tooth surface by assuming the tool surface as the error surface, where actual tool installation position error is introduced into the equation of virtual shaper cutter. Surface equations and 3-D models for the face gear and the worm wheel involving four kinds of tool installation errors are established. When compared, the face gear tooth surface machined in VERICUT software for simulation based on this new method and the one obtained based on real process(grinding face gear by using a theoretical worm wheel with actual position errors) are found to be coincident, which proves the validity and feasibility of this new method. By using mesh planning for the rotating projection plane of the face gear work tooth surface, the deviation values of the tooth surface and the difference surface are acquired, and the influence of four kinds of errors on the face gear tooth surface is analyzed. Accordingly, this work provides a theoretical reference for assembly craft of worm wheel, improvement of face gear machining accuracy and modification of error tooth surface.展开更多
China announced plans on April 1,2017 to create Xiong＇an New Area,a new economic zone about 110 km southwest of Beijing.The new area of national significance covers the three counties of Xiongxian,Rongcheng and Anxin...China announced plans on April 1,2017 to create Xiong＇an New Area,a new economic zone about 110 km southwest of Beijing.The new area of national significance covers the three counties of Xiongxian,Rongcheng and Anxin in Hebei Province,and is home to Baiyangdian,a major wetland in northern China.It will cover around 100 km2 initially（called ＂Starting Zone＂） and will be expanded to 200 km2 in the mid-term and about 2000 km2 in the long term.In this context,it is important to assess the land use pattern for the new area＇s planning and development.Based on remote sensing interpretation of Landsat OLI images,we examine the current land use features,the potential for built-up land saving and intensive use,and the spatial variation of arable land quality.The results indicate that the arable lands,built-up lands and wetlands account for around 60%,20% and 10%,respectively.The potential for rural built-up land saving and intensive use is quite large.The arable land quality and use intensity in Rongcheng and Anxin counties are much better than that of Xiongxian.The pros and cons for three potential options for the Starting Zone are listed and compared.The eastern area of Rongcheng county,to the north of Baiyangdian,is believed to be the most suitable Starting Zone.Policy recommendations for built-up land expansion,farmland saving and flood risk mitigation for Xiong＇an New Area are also proposed in this paper.展开更多
文摘In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc networks is proposed.In this scheme, a sender can simultaneously signcrypt n messeges for n receivers, and a receiver can unsigncrypt the ciphertext to get his message with his own private key.An analysis of this scheme indicates that it achieves authenticity and confidentiality in the random oracle model while being of lower computation and communication overhead.Finally, for the application of our scheme in ad hoc, a threshold key updating protocol for ad hoc networks is given.
基金Projects(51535012,U1604255)supported by the National Natural Science Foundation of ChinaProject(2016JC2001)supported by the Key Research and Development Project of Hunan Province,China
文摘The machining principle and realization method for the continuous generative grinding face gear by a worm wheel are introduced. Based on a five-axis linked CNC grinding machine, a new method is presented to deprive the equation of face gear error tooth surface by assuming the tool surface as the error surface, where actual tool installation position error is introduced into the equation of virtual shaper cutter. Surface equations and 3-D models for the face gear and the worm wheel involving four kinds of tool installation errors are established. When compared, the face gear tooth surface machined in VERICUT software for simulation based on this new method and the one obtained based on real process(grinding face gear by using a theoretical worm wheel with actual position errors) are found to be coincident, which proves the validity and feasibility of this new method. By using mesh planning for the rotating projection plane of the face gear work tooth surface, the deviation values of the tooth surface and the difference surface are acquired, and the influence of four kinds of errors on the face gear tooth surface is analyzed. Accordingly, this work provides a theoretical reference for assembly craft of worm wheel, improvement of face gear machining accuracy and modification of error tooth surface.
基金National Natural Science Foundation of China(41430861)National Key Research and Development Program(2016YFC0503501)Youth Innovation Promotion Association of Chinese Academy of Sciences(2014040)
文摘China announced plans on April 1,2017 to create Xiong＇an New Area,a new economic zone about 110 km southwest of Beijing.The new area of national significance covers the three counties of Xiongxian,Rongcheng and Anxin in Hebei Province,and is home to Baiyangdian,a major wetland in northern China.It will cover around 100 km2 initially（called ＂Starting Zone＂） and will be expanded to 200 km2 in the mid-term and about 2000 km2 in the long term.In this context,it is important to assess the land use pattern for the new area＇s planning and development.Based on remote sensing interpretation of Landsat OLI images,we examine the current land use features,the potential for built-up land saving and intensive use,and the spatial variation of arable land quality.The results indicate that the arable lands,built-up lands and wetlands account for around 60%,20% and 10%,respectively.The potential for rural built-up land saving and intensive use is quite large.The arable land quality and use intensity in Rongcheng and Anxin counties are much better than that of Xiongxian.The pros and cons for three potential options for the Starting Zone are listed and compared.The eastern area of Rongcheng county,to the north of Baiyangdian,is believed to be the most suitable Starting Zone.Policy recommendations for built-up land expansion,farmland saving and flood risk mitigation for Xiong＇an New Area are also proposed in this paper.
