当目标临近最近通过点(Closest Point of Approach,CPA)时,与水听器之间的距离随时间呈非线性变化,基于干涉条纹斜率的波导不变量测距方法受限。本文提出一种利用简正波水平波数差与波导不变量的关系式实现目标参数估计方法。利用运动...当目标临近最近通过点(Closest Point of Approach,CPA)时,与水听器之间的距离随时间呈非线性变化,基于干涉条纹斜率的波导不变量测距方法受限。本文提出一种利用简正波水平波数差与波导不变量的关系式实现目标参数估计方法。利用运动目标通过CPA位置时在水平阵两端阵元产生的宽带连续谱干涉条纹,获得其最近通过时间t_(cpa1)和t_(cpa2),再利用几何关系和简正波水平波数差与波导不变量的关系式得到阵元1和阵元2的最近通过距离r_(cpa1)和r_(cpa2)以及目标运动速度v_(0),最终估计出运动目标相对接收阵几何中心的距离随时间变化曲线。数值仿真表明,本文方法可有效利用临近CPA位置处的时间频率域一定曲率的干涉条纹,实现运动目标参数估计。展开更多
Cerebellopontine angle (CPA) lesions account for up to 10% of all intracranial tumors. Most CPA tumors are benign, but can cause nerve damage or compress the surrounding structures if left untreated. The typical prese...Cerebellopontine angle (CPA) lesions account for up to 10% of all intracranial tumors. Most CPA tumors are benign, but can cause nerve damage or compress the surrounding structures if left untreated. The typical presentation is with adult-onset sensorineural hearing loss or non-pulsatile tinnitus. In some patients, this goes unnoticed, and presentation is delayed until the lesion is much larger and presents with symptoms related to mass effect. We present the case study of 63 years old gentleman, who had suspected left CPA lesion on CT head done few years ago for dizziness and left-sided facial numbness. MRI could not be done at that time due to his MRI incompatible pacemaker leading to delay in his management eventually causing loss of patient to the follow up. He later developed progressive difficulty in walking which was initially attributed to as secondary to vasovagal syncope and postural hypotension. He eventually presented to us with intractable nausea and vomiting, worsening headache and ataxia. He had an urgent CT head which showed significant growth in the lesion with compression of the surrounding structures and obstructive hydrocephalus. He was given steroids which improved his nausea and vomiting, followed by undergoing surgery in regional center leading to significant improvement in his gait within few days of surgery. He unfortunately continued to have a degree of ataxia and facial numbness. This case illustrates a rare presentation of CPA tumor with symptoms of nausea and vomiting as a result of mass effect of the growing tumor. In addition, this review also shows the importance of regularly following up the patients with suspected CPA lesions on initial scans which will help with identifying the increase in size of lesion promptly and potentially preventing advanced complications of CPA tumors. We suggest regular monitoring of these patients to timely manage the lesion and avoid the potential life-threatening complications.展开更多
文摘当目标临近最近通过点(Closest Point of Approach,CPA)时,与水听器之间的距离随时间呈非线性变化,基于干涉条纹斜率的波导不变量测距方法受限。本文提出一种利用简正波水平波数差与波导不变量的关系式实现目标参数估计方法。利用运动目标通过CPA位置时在水平阵两端阵元产生的宽带连续谱干涉条纹,获得其最近通过时间t_(cpa1)和t_(cpa2),再利用几何关系和简正波水平波数差与波导不变量的关系式得到阵元1和阵元2的最近通过距离r_(cpa1)和r_(cpa2)以及目标运动速度v_(0),最终估计出运动目标相对接收阵几何中心的距离随时间变化曲线。数值仿真表明,本文方法可有效利用临近CPA位置处的时间频率域一定曲率的干涉条纹,实现运动目标参数估计。
文摘Cerebellopontine angle (CPA) lesions account for up to 10% of all intracranial tumors. Most CPA tumors are benign, but can cause nerve damage or compress the surrounding structures if left untreated. The typical presentation is with adult-onset sensorineural hearing loss or non-pulsatile tinnitus. In some patients, this goes unnoticed, and presentation is delayed until the lesion is much larger and presents with symptoms related to mass effect. We present the case study of 63 years old gentleman, who had suspected left CPA lesion on CT head done few years ago for dizziness and left-sided facial numbness. MRI could not be done at that time due to his MRI incompatible pacemaker leading to delay in his management eventually causing loss of patient to the follow up. He later developed progressive difficulty in walking which was initially attributed to as secondary to vasovagal syncope and postural hypotension. He eventually presented to us with intractable nausea and vomiting, worsening headache and ataxia. He had an urgent CT head which showed significant growth in the lesion with compression of the surrounding structures and obstructive hydrocephalus. He was given steroids which improved his nausea and vomiting, followed by undergoing surgery in regional center leading to significant improvement in his gait within few days of surgery. He unfortunately continued to have a degree of ataxia and facial numbness. This case illustrates a rare presentation of CPA tumor with symptoms of nausea and vomiting as a result of mass effect of the growing tumor. In addition, this review also shows the importance of regularly following up the patients with suspected CPA lesions on initial scans which will help with identifying the increase in size of lesion promptly and potentially preventing advanced complications of CPA tumors. We suggest regular monitoring of these patients to timely manage the lesion and avoid the potential life-threatening complications.
