When an unruptured aneurysm is found, deciding whether to operate or follow up is one of the most important issues. There are guidelines for making the best final decision on treatment, taking into account the effecti...When an unruptured aneurysm is found, deciding whether to operate or follow up is one of the most important issues. There are guidelines for making the best final decision on treatment, taking into account the effectiveness of diagnostic and therapeutic devices and the risk-benefit ratio of patients, caregivers, and healthcare professionals. The guidelines evidence-based of large clinical data for this purpose are presented by national medical societies. As one of the rupture risk indicators, there is the hazard risk ratio derived by the UCAS Japan research group based on the statistical method of 6697 aneurysms in 5720 patients with cerebral aneurysms of 3 mm or more. Therefore, we investigated the biomechanical significance of this hazard risk ratio using a spherical aneurysm model. It was revealed that 1) the reason why the frequency of aneurysm rupture is relatively high up to about 10 mm, 2) the UCAS hazard risk ratio corresponds to stress of the aneurysm wall, and the true stress can be calculated by multiplying the patient’s blood pressure, and 3) the factors that cause the daughter’s sac (irregular protrusion of the aneurysm wall). In addition, our two methods for measuring the strength of the blood vessel wall of an individual patient were described.展开更多
Due to the potential capacity-boosting for wireless communications,radio vortex wireless communication(RowComm)over orthogonal states/modes of orbital angular momentum(OAM)has been paid much attention to in recent yea...Due to the potential capacity-boosting for wireless communications,radio vortex wireless communication(RowComm)over orthogonal states/modes of orbital angular momentum(OAM)has been paid much attention to in recent years.A uniform circular array(UCA),as an efficient and convenient antenna structure,can transmit/receive multiple OAM beams with different OAM-modes simultaneously when the transmitter and receiver are aligned.However,for high-order OAMmodes,the OAM beams are divergent accompanied by severe attenuation.Thus,it is difficult to directly use high-order OAM-modes to achieve high capacity for RowComms.To obtain high capacity potentially offered by OAM-modes,in this paper we transform the singular UCA into the concentric UCAs,where high capacity can be achieved using multiple parallel low-order OAM-modes instead of all high-order OAM-modes,to increase the capacity of transmitter-receiver aligned Row-Comms.In particular,we study two cases:1).concentric UCAs based RowComms without co-mode interference;2).concentric UCAs based RowComms with co-mode interference.We propose a co-mode-interference-free and a co-mode-interference-contained mode-decomposition schemes to recover transmitted signals for these two cases,respectively.Additionally,we develop optimal power allocation schemes to maximize the capacity for these two cases.Numerical simulations are presented to validate and evaluate that our developed concentric UCAs based low-order RowComms can significantly increase the capacity as compared with that of singular UCA based RowComms.展开更多
A dimension decomposition(DIDE)method for multiple incoherent source localization using uniform circular array(UCA)is proposed.Due to the fact that the far-field signal can be considered as the state where the range p...A dimension decomposition(DIDE)method for multiple incoherent source localization using uniform circular array(UCA)is proposed.Due to the fact that the far-field signal can be considered as the state where the range parameter of the nearfield signal is infinite,the algorithm for the near-field source localization is also suitable for estimating the direction of arrival(DOA)of far-field signals.By decomposing the first and second exponent term of the steering vector,the three-dimensional(3-D)parameter is transformed into two-dimensional(2-D)and onedimensional(1-D)parameter estimation.First,by partitioning the received data,we exploit propagator to acquire the noise subspace.Next,the objective function is established and partial derivative is applied to acquire the spatial spectrum of 2-D DOA.At last,the estimated 2-D DOA is utilized to calculate the phase of the decomposed vector,and the least squares(LS)is performed to acquire the range parameters.In comparison to the existing algorithms,the proposed DIDE algorithm requires neither the eigendecomposition of covariance matrix nor the search process of range spatial spectrum,which can achieve satisfactory localization and reduce computational complexity.Simulations are implemented to illustrate the advantages of the proposed DIDE method.Moreover,simulations demonstrate that the proposed DIDE method can also classify the mixed far-field and near-field signals.展开更多
文摘When an unruptured aneurysm is found, deciding whether to operate or follow up is one of the most important issues. There are guidelines for making the best final decision on treatment, taking into account the effectiveness of diagnostic and therapeutic devices and the risk-benefit ratio of patients, caregivers, and healthcare professionals. The guidelines evidence-based of large clinical data for this purpose are presented by national medical societies. As one of the rupture risk indicators, there is the hazard risk ratio derived by the UCAS Japan research group based on the statistical method of 6697 aneurysms in 5720 patients with cerebral aneurysms of 3 mm or more. Therefore, we investigated the biomechanical significance of this hazard risk ratio using a spherical aneurysm model. It was revealed that 1) the reason why the frequency of aneurysm rupture is relatively high up to about 10 mm, 2) the UCAS hazard risk ratio corresponds to stress of the aneurysm wall, and the true stress can be calculated by multiplying the patient’s blood pressure, and 3) the factors that cause the daughter’s sac (irregular protrusion of the aneurysm wall). In addition, our two methods for measuring the strength of the blood vessel wall of an individual patient were described.
文摘Due to the potential capacity-boosting for wireless communications,radio vortex wireless communication(RowComm)over orthogonal states/modes of orbital angular momentum(OAM)has been paid much attention to in recent years.A uniform circular array(UCA),as an efficient and convenient antenna structure,can transmit/receive multiple OAM beams with different OAM-modes simultaneously when the transmitter and receiver are aligned.However,for high-order OAMmodes,the OAM beams are divergent accompanied by severe attenuation.Thus,it is difficult to directly use high-order OAM-modes to achieve high capacity for RowComms.To obtain high capacity potentially offered by OAM-modes,in this paper we transform the singular UCA into the concentric UCAs,where high capacity can be achieved using multiple parallel low-order OAM-modes instead of all high-order OAM-modes,to increase the capacity of transmitter-receiver aligned Row-Comms.In particular,we study two cases:1).concentric UCAs based RowComms without co-mode interference;2).concentric UCAs based RowComms with co-mode interference.We propose a co-mode-interference-free and a co-mode-interference-contained mode-decomposition schemes to recover transmitted signals for these two cases,respectively.Additionally,we develop optimal power allocation schemes to maximize the capacity for these two cases.Numerical simulations are presented to validate and evaluate that our developed concentric UCAs based low-order RowComms can significantly increase the capacity as compared with that of singular UCA based RowComms.
基金supported by the National Natural Science Foundation of China(62022091,61921001).
文摘A dimension decomposition(DIDE)method for multiple incoherent source localization using uniform circular array(UCA)is proposed.Due to the fact that the far-field signal can be considered as the state where the range parameter of the nearfield signal is infinite,the algorithm for the near-field source localization is also suitable for estimating the direction of arrival(DOA)of far-field signals.By decomposing the first and second exponent term of the steering vector,the three-dimensional(3-D)parameter is transformed into two-dimensional(2-D)and onedimensional(1-D)parameter estimation.First,by partitioning the received data,we exploit propagator to acquire the noise subspace.Next,the objective function is established and partial derivative is applied to acquire the spatial spectrum of 2-D DOA.At last,the estimated 2-D DOA is utilized to calculate the phase of the decomposed vector,and the least squares(LS)is performed to acquire the range parameters.In comparison to the existing algorithms,the proposed DIDE algorithm requires neither the eigendecomposition of covariance matrix nor the search process of range spatial spectrum,which can achieve satisfactory localization and reduce computational complexity.Simulations are implemented to illustrate the advantages of the proposed DIDE method.Moreover,simulations demonstrate that the proposed DIDE method can also classify the mixed far-field and near-field signals.
