摘要 :
With the broad application of satellite navigation technique in the society and economy development, the satellite navigation technique has been facing with more and more hidden dangers of being attacked in such key fields as fina...
展开
With the broad application of satellite navigation technique in the society and economy development, the satellite navigation technique has been facing with more and more hidden dangers of being attacked in such key fields as finance, public security, civil aviation and public rescue. In light of the vulnerability of satellite navigation receiver against replay attack in the above fields, this paper proposes several anti-replay attack techniques of low complexity, i.e., inertial positioning test, clock skew test and Doppler shift test. The simulation results show that Doppler shift test can resist replay attack effectively without additional hardware to the receiver. In addition, compared to SNR test, absolute power test and the other techniques, Doppler shift test has the advantages of low implementation difficulty and high adaptability, which can provide technical support for the security applications of satellite navigation technology in the fields of great concern.
收起
摘要 :
With the broad application of satellite navigation technique in the society and economy development, the satellite navigation technique has been facing with more and more hidden dangers of being attacked in such key fields as fina...
展开
With the broad application of satellite navigation technique in the society and economy development, the satellite navigation technique has been facing with more and more hidden dangers of being attacked in such key fields as finance, public security, civil aviation and public rescue. In light of the vulnerability of satellite navigation receiver against replay attack in the above fields, this paper proposes several anti-replay attack techniques of low complexity, i.e., inertial positioning test, clock skew test and Doppler shift test. The simulation results show that Doppler shift test can resist replay attack effectively without additional hardware to the receiver. In addition, compared to SNR test, absolute power test and the other techniques, Doppler shift test has the advantages of low implementation difficulty and high adaptability, which can provide technical support for the security applications of satellite navigation technology in the fields of great concern.
收起
摘要 :
Considering the dynamic nonlinear characteristics of soil by equivalent linear method, one-dimensional wave models were established to study the seismic effects along depth of deep soft sites under far-field ground motions of grea...
展开
Considering the dynamic nonlinear characteristics of soil by equivalent linear method, one-dimensional wave models were established to study the seismic effects along depth of deep soft sites under far-field ground motions of great earthquake. The results show that the magnified effect of acceleration response spectrum of each layer present more outstanding under far-field ground motions than under Suzhou artificial waves, with the increasing of bedrock peak ground acceleration, there is probability that the peak of long-period component of acceleration response spectrum appears higher than that of the short-period within 15m depth, which may adversely affect the long-period building structures. However, the reduction coefficient of peak ground acceleration (PGA) along depth according to the three levels of earthquake fortification standard was relatively higher when inputting far-field ground motions of great earthquake. As the curve fitted by Longjun Xu et al. based on records collected California Strong Motion Instrumentation Program geotechnical arrays of the United States and Hosokura Mine arrays of Japan, is not suitable for Suzhou area, suited quantitative formula about reduction coefficient curve of PGA with depth in deep soft site is given. Besides, maximum shear strain at the depth of approximately 15m and 40m present to be greatly changed when inputting far-field ground motions of great earthquake, with the growth of inputting bedrock peak ground acceleration, the layer in the depth of about 15m comes to be the most unfavorable position of shear deformation.
收起
摘要 :
Considering the dynamic nonlinear characteristics of soil by equivalent linear method, one-dimensional wave models were established to study the seismic effects along depth of deep soft sites under far-field ground motions of grea...
展开
Considering the dynamic nonlinear characteristics of soil by equivalent linear method, one-dimensional wave models were established to study the seismic effects along depth of deep soft sites under far-field ground motions of great earthquake. The results show that the magnified effect of acceleration response spectrum of each layer present more outstanding under far-field ground motions than under Suzhou artificial waves, with the increasing of bedrock peak ground acceleration, there is probability that the peak of long-period component of acceleration response spectrum appears higher than that of the short-period within 15m depth, which may adversely affect the long-period building structures. However, the reduction coefficient of peak ground acceleration (PGA) along depth according to the three levels of earthquake fortification standard was relatively higher when inputting far-field ground motions of great earthquake. As the curve fitted by Longjun Xu et al. based on records collected California Strong Motion Instrumentation Program geotechnical arrays of the United States and Hosokura Mine arrays of Japan, is not suitable for Suzhou area, suited quantitative formula about reduction coefficient curve of PGA with depth in deep soft site is given. Besides, maximum shear strain at the depth of approximately 15m and 40m present to be greatly changed when inputting far-field ground motions of great earthquake, with the growth of inputting bedrock peak ground acceleration, the layer in the depth of about 15m comes to be the most unfavorable position of shear deformation.
收起
摘要 :
Considering the dynamic nonlinear characteristics of soil by equivalent linear method, one-dimensional wave models were established to study the seismic effects along depth of deep soft sites under far-field ground motions of grea...
展开
Considering the dynamic nonlinear characteristics of soil by equivalent linear method, one-dimensional wave models were established to study the seismic effects along depth of deep soft sites under far-field ground motions of great earthquake. The results show that the magnified effect of acceleration response spectrum of each layer present more outstanding under far-field ground motions than under Suzhou artificial waves, with the increasing of bedrock peak ground acceleration, there is probability that the peak of long-period component of acceleration response spectrum appears higher than that of the short-period within 15m depth, which may adversely affect the long-period building structures. However, the reduction coefficient of peak ground acceleration (PGA) along depth according to the three levels of earthquake fortification standard was relatively higher when inputting far-field ground motions of great earthquake. As the curve fitted by Longjun Xu et al. based on records collected California Strong Motion Instrumentation Program geotechnical arrays of the United States and Hosokura Mine arrays of Japan, is not suitable for Suzhou area, suited quantitative formula about reduction coefficient curve of PGA with depth in deep soft site is given. Besides, maximum shear strain at the depth of approximately 15m and 40m present to be greatly changed when inputting far-field ground motions of great earthquake, with the growth of inputting bedrock peak ground acceleration, the layer in the depth of about 15m comes to be the most unfavorable position of shear deformation.
收起
摘要 :
Due to the rapid growth in the use of wireless communication systems, there has been a recent increase in public concern regarding the exposure of humans to radio frequency (RF) electromagnetic radiation. This is particularly evid...
展开
Due to the rapid growth in the use of wireless communication systems, there has been a recent increase in public concern regarding the exposure of humans to radio frequency (RF) electromagnetic radiation. This is particularly evident in the case of mobile telephone handsets. This paper aims to provide an investigation of the effectiveness of various commercially available Specific Absorption Rate (SAR) reduction products and shielding materials that can be externally attached to the handsets in Hong Kong. Also, the SAR values of different mobile phones are measured. Results are compared to the USA and European standards and then characterized for SAR reduction applications.
收起
摘要 :
Magnetic Resonance Imaging (MRI) has been contraindicated in patients with pacemakers or implantable cardioverter-defibrillators (ICDs) due to safety concerns, such as the heating of adjacent bodily tissue due to radio frequency (...
展开
Magnetic Resonance Imaging (MRI) has been contraindicated in patients with pacemakers or implantable cardioverter-defibrillators (ICDs) due to safety concerns, such as the heating of adjacent bodily tissue due to radio frequency (RF) induced current. The ISO/IEC 10974 Joint Working Group (JWG) has developed a tiered approach in establishing the worst case RF heating conditions that active implantable devices may experience during MRI utilizing computer simulations. According to the ISO/IEC JWG tier 2 approach, we evaluated the electric fields induced in the implant regions of pacemakers and ICDs in five human body models during 1.5 T MRI scans. The maximum electrical field (Emax) can be used as a conservative estimation to test MRI induced heating. The SEMCAD software package was used to calculate the electric field distribution due to RF fields from high pass and low pass MRI birdcage coils. The variables studied in the simulations also included circularly polarized field rotations, body positions inside RF coils (landmark positions), tissue properties, and RF coil size. The Emax and 95 percentile electric field values were computed from the simulations at each of multiple implant regions.
收起
摘要 :
Magnetic Resonance Imaging (MRI) has been contraindicated in patients with pacemakers or implantable cardioverter-defibrillators (ICDs) due to safety concerns, such as the heating of adjacent bodily tissue due to radio frequency (...
展开
Magnetic Resonance Imaging (MRI) has been contraindicated in patients with pacemakers or implantable cardioverter-defibrillators (ICDs) due to safety concerns, such as the heating of adjacent bodily tissue due to radio frequency (RF) induced current. The ISO/IEC 10974 Joint Working Group (JWG) has developed a tiered approach in establishing the worst case RF heating conditions that active implantable devices may experience during MRI utilizing computer simulations. According to the ISO/IEC JWG tier 2 approach, we evaluated the electric fields induced in the implant regions of pacemakers and ICDs in five human body models during 1.5 T MRI scans. The maximum electrical field (Emax) can be used as a conservative estimation to test MRI induced heating. The SEMCAD software package was used to calculate the electric field distribution due to RF fields from high pass and low pass MRI birdcage coils. The variables studied in the simulations also included circularly polarized field rotations, body positions inside RF coils (landmark positions), tissue properties, and RF coil size. The Emax and 95 percentile electric field values were computed from the simulations at each of multiple implant regions.
收起
原文获取