To solve the problem of the sky-wave interference in radio positioning system operating in CDMA mode, an algorithm of sky-ground-wave separation is provided. Based on the MLE （maximum likelihood estimate）, and by es...To solve the problem of the sky-wave interference in radio positioning system operating in CDMA mode, an algorithm of sky-ground-wave separation is provided. Based on the MLE （maximum likelihood estimate）, and by estimating the amplitude and the phase of the sky-wave signal, the provided algorithm for separating skyground-wave is implemented. The mathematics model used for signal processing is established, and the possible solutions are provided. The structure and signal processing flow implementing the presented algorithm in the receiver are presented. A multi-channels signal searching idea is adopted, some of which process the sky-wave signal, and some of which process the ground-wave signal. Numerical analysis and simulation show that the proposed algorithm has higher accuracy, more rapid processing speed, and simpler implementation for the estimation of the sky-wave signal parameter, and can separate the sky-wave signal and ground-wave signal from the arrival combination signal effectively.展开更多
Background:This study aimed to investigate the value of high field-strength intraoperative magnetic resonance imaging(iMRI)-guided stereotactic biopsy in the surgery of intracranial space-occupying lesions.Methods:A t...Background:This study aimed to investigate the value of high field-strength intraoperative magnetic resonance imaging(iMRI)-guided stereotactic biopsy in the surgery of intracranial space-occupying lesions.Methods:A total of 87 patients who underwent stereotactic biopsy of intracranial lesions in the Peking University International Hospital from March 2016 to August 2018 were retrospectively surveyed;among these,50 patients underwent MRI-guided stereotactic biopsy using the Leksell frame(iMRI group)and 37 cases received traditional stereotactic biopsy using the Leksell frame(control group).The accuracy rates and complications of the two groups were compared.Results:A 100%positive diagnosis was observed in all cases(n=50)in the iMRI group.In 4 cases,the biopsy site was clearly found to have deviated from the target point,and the biopsy was performed again.The control group had 33 cases(86.5%)with positive diagnosis.No severe complications like neural functional deficit were observed in the iMRI group,while two patients developed bleeding at the puncture site(1 case receiving surgery to remove the hematoma)in the control group.There were no deaths in either group.Conclusion:iMRI-assisted stereotactic biopsy can confirm the target position and adjust the puncture path in real time.Compared to the traditional stereotactic biopsy technique,the iMRI method has a higher positive diagnostic rate,though surgical trauma and complications have no significant difference.展开更多
文摘To solve the problem of the sky-wave interference in radio positioning system operating in CDMA mode, an algorithm of sky-ground-wave separation is provided. Based on the MLE （maximum likelihood estimate）, and by estimating the amplitude and the phase of the sky-wave signal, the provided algorithm for separating skyground-wave is implemented. The mathematics model used for signal processing is established, and the possible solutions are provided. The structure and signal processing flow implementing the presented algorithm in the receiver are presented. A multi-channels signal searching idea is adopted, some of which process the sky-wave signal, and some of which process the ground-wave signal. Numerical analysis and simulation show that the proposed algorithm has higher accuracy, more rapid processing speed, and simpler implementation for the estimation of the sky-wave signal parameter, and can separate the sky-wave signal and ground-wave signal from the arrival combination signal effectively.
文摘Background:This study aimed to investigate the value of high field-strength intraoperative magnetic resonance imaging(iMRI)-guided stereotactic biopsy in the surgery of intracranial space-occupying lesions.Methods:A total of 87 patients who underwent stereotactic biopsy of intracranial lesions in the Peking University International Hospital from March 2016 to August 2018 were retrospectively surveyed;among these,50 patients underwent MRI-guided stereotactic biopsy using the Leksell frame(iMRI group)and 37 cases received traditional stereotactic biopsy using the Leksell frame(control group).The accuracy rates and complications of the two groups were compared.Results:A 100%positive diagnosis was observed in all cases(n=50)in the iMRI group.In 4 cases,the biopsy site was clearly found to have deviated from the target point,and the biopsy was performed again.The control group had 33 cases(86.5%)with positive diagnosis.No severe complications like neural functional deficit were observed in the iMRI group,while two patients developed bleeding at the puncture site(1 case receiving surgery to remove the hematoma)in the control group.There were no deaths in either group.Conclusion:iMRI-assisted stereotactic biopsy can confirm the target position and adjust the puncture path in real time.Compared to the traditional stereotactic biopsy technique,the iMRI method has a higher positive diagnostic rate,though surgical trauma and complications have no significant difference.
