简述了甚小口径天线终端(very small aperture terminal,VSAT)和超小口径天线终端(ultra small aperture terminal,USAT)站天线口径的划分及等效口径的计算方法.系统介绍了VSAT和USAT站天线性能的设计目标,即天线方向图的旁瓣特性、交...简述了甚小口径天线终端(very small aperture terminal,VSAT)和超小口径天线终端(ultra small aperture terminal,USAT)站天线口径的划分及等效口径的计算方法.系统介绍了VSAT和USAT站天线性能的设计目标,即天线方向图的旁瓣特性、交叉极化特性和偏轴等效各向同性辐射功率.指出了VSAT和USAT站卫星通信天线性能设计目标的局限性,并提出了VSAT和USAT站天线方向图第一旁瓣电平要求的建议.展开更多
近年来,空间通信卫星数量快速增长,由于卫星通信系统工作频率有限,因此当两个覆盖区有重叠的通信卫星轨道间隔较近时,区域内同频率的超小口径天线终端(Ultra Small Aperture Terminal,USAT)动中通系统之间将会产生邻星干扰。结合USAT与...近年来,空间通信卫星数量快速增长,由于卫星通信系统工作频率有限,因此当两个覆盖区有重叠的通信卫星轨道间隔较近时,区域内同频率的超小口径天线终端(Ultra Small Aperture Terminal,USAT)动中通系统之间将会产生邻星干扰。结合USAT与静止卫星单邻星干扰模型,详细阐述了邻星干扰成因,推导了卫星轨位间隔与静止卫星单邻星干扰容限的关系;同时研究了邻星干扰下的链路载干噪比门限备余量设计问题。最后基于数值仿真结果,分析了轨位间隔、干扰终端发射功率及终端天线口径对邻星干扰容限的影响,提出了几种有效的邻星干扰对策。展开更多
Thromboembolic diseases continue to be one of the most prevalent medical problems today and can lead to life-threatening conditions, such as pulmonary embolism (PE). Currently, PE diagnosis and treatment are a challen...Thromboembolic diseases continue to be one of the most prevalent medical problems today and can lead to life-threatening conditions, such as pulmonary embolism (PE). Currently, PE diagnosis and treatment are a challenge because of acute onset right ventricular strain with right-sided heart failure, sudden death, pulmonary infarction, and cardiogenic shock, which limit the time for therapeutic success.?The aim of this study was to evaluate our perception, knowledge, and concerns regarding PE, discuss the importance of promptly diagnosing PE to provide appropriate treatment options for this life-threatening condition, list the most common clinical manifestations present when PE is suspected, and review the clinical approach to patients with suspected PE in an inpatient setting.?In addition, this study reviews the risk stratification of patients with PE and treatment options beyond anticoagulation, compares new treatment options for patients presenting with acute symptomatic PE, and compares aspiration catheters (10 F Pronto .035” and 14 F XL extraction catheter (Vascular Solutions, Minneapolis, MN)) and ultrasound-assisted catheter-directed thrombolysis (USAT) versus systemic thrombolysis.This literature review was limited by the quality and number of studies available regarding new treatment options for patients presenting with acute symptomatic PE. Thus, more studies are needed to prove the validity of newer treatment options being trialed, such as aspiration catheters (10 F Pronto .035” and 14 F XL extraction catheter) and USAT, with the hope that further studies will guide patient management and increase our understanding of next generation aspiration catheters, which may provide novel insights on treating acute symptomatic PE.展开更多
文摘简述了甚小口径天线终端(very small aperture terminal,VSAT)和超小口径天线终端(ultra small aperture terminal,USAT)站天线口径的划分及等效口径的计算方法.系统介绍了VSAT和USAT站天线性能的设计目标,即天线方向图的旁瓣特性、交叉极化特性和偏轴等效各向同性辐射功率.指出了VSAT和USAT站卫星通信天线性能设计目标的局限性,并提出了VSAT和USAT站天线方向图第一旁瓣电平要求的建议.
文摘近年来,空间通信卫星数量快速增长,由于卫星通信系统工作频率有限,因此当两个覆盖区有重叠的通信卫星轨道间隔较近时,区域内同频率的超小口径天线终端(Ultra Small Aperture Terminal,USAT)动中通系统之间将会产生邻星干扰。结合USAT与静止卫星单邻星干扰模型,详细阐述了邻星干扰成因,推导了卫星轨位间隔与静止卫星单邻星干扰容限的关系;同时研究了邻星干扰下的链路载干噪比门限备余量设计问题。最后基于数值仿真结果,分析了轨位间隔、干扰终端发射功率及终端天线口径对邻星干扰容限的影响,提出了几种有效的邻星干扰对策。
文摘Thromboembolic diseases continue to be one of the most prevalent medical problems today and can lead to life-threatening conditions, such as pulmonary embolism (PE). Currently, PE diagnosis and treatment are a challenge because of acute onset right ventricular strain with right-sided heart failure, sudden death, pulmonary infarction, and cardiogenic shock, which limit the time for therapeutic success.?The aim of this study was to evaluate our perception, knowledge, and concerns regarding PE, discuss the importance of promptly diagnosing PE to provide appropriate treatment options for this life-threatening condition, list the most common clinical manifestations present when PE is suspected, and review the clinical approach to patients with suspected PE in an inpatient setting.?In addition, this study reviews the risk stratification of patients with PE and treatment options beyond anticoagulation, compares new treatment options for patients presenting with acute symptomatic PE, and compares aspiration catheters (10 F Pronto .035” and 14 F XL extraction catheter (Vascular Solutions, Minneapolis, MN)) and ultrasound-assisted catheter-directed thrombolysis (USAT) versus systemic thrombolysis.This literature review was limited by the quality and number of studies available regarding new treatment options for patients presenting with acute symptomatic PE. Thus, more studies are needed to prove the validity of newer treatment options being trialed, such as aspiration catheters (10 F Pronto .035” and 14 F XL extraction catheter) and USAT, with the hope that further studies will guide patient management and increase our understanding of next generation aspiration catheters, which may provide novel insights on treating acute symptomatic PE.
