Doppler

摘要： BACKGROUND Early scar pregnancy(CSP)in the lower uterine segment after cesarean section is a type of ectopic pregnancy that can cause major complications if left untreated.Transabdominal ultrasound is a common procedure but is influenced by external factors.Thus,intracavitary ultrasound may have better diagnostic efficiency for CSP.AIM To assess the value of intracavitary ultrasound for diagnosing CSP in the lower uterine segment after cesarean section.METHODS Patients diagnosed with CSP in our hospital from October 2019 to April 2021 were recruited.Transabdominal and intracavitary ultrasound examinations were performed to compare the diagnostic differences for CSP and its types.RESULTS Sixty-three patients were diagnosed during the study period.The diagnostic accuracy for CSP was higher in intracavitary ultrasound(96.83%)than in transabdominal ultrasound(84.13%)(P0.05).For the diagnostic rates for the CSP types,the rates for gestational sac(100.00%vs 90.48%),heterogeneous mass(93.75%vs 75.00%),and part of the uterine cavity(80.00%vs 60.00%)were higher in intracavitary ultrasound than in transabdominal ultrasound,but the difference was not statistically significant(P>0.05).For gestational sac CSP patients,intracavitary ultrasound showed that the gestational sac was located in the lower uterine segment scar with abundant peripheral blood flow;the distance between the gestational sac and the serosal layer was 2.42±0.50 cm.Intracavitary ultrasound for heterogeneous mass CSP patients indicated that the mass mainly occurred in the lower anterior uterine wall,protruding into the bladder,and was surrounded by abundant internal and peripheral blood flow;the distance between the mass and serosal layer was 1.79±0.30 cm.For CSP type partly located in the uterine cavity,the gestational sac was partly located in the lower uterine cavity and partly in the scar with abundant internal and peripheral blood flow;the distance between the gestational sac and the serosal layer was 2.29±0.28 cm.CONCLUSION Intracavitary ultrasound had a higher diagnostic accuracy and application value for diagnosing CSP than transabdominal ultrasound,with reduced risk of missed diagnoses and misdiagnosis,thereby preventing delayed treatment.

摘要： This paper formulates the light timing calculations for each interferometer arm;one that is parallel to the direction of motion of the interferometer through space and the other that is perpendicular. The calculations are done for a vacuum-mode interferometer and then for a gas-mode interferometer. The calculations show that no light timing difference is detectable in a vacuum-mode interferometer, but once an optical medium is present in the light path down the arms of the interferometer, this is no longer the case and a timing difference is detectable. Further to this, the timing equations obtained from the analysis are used to model the historical experiments of Michelson-Morley and Miller (Mt Wilson) and predictions are made by the model that accurately match the actual recorded results from those experiments. Thus, this timing analysis confirms that there is a light speed anisotropy in a reference frame that is moving through space, indicating the presence of a preferred Aether reference frame through which the Earth is moving.

摘要： Objective:To investigate the effects of a single oxytocin injection on plasma steroid concentrations,testicular blood flow measures(resistive and pulsatility indexes),and testicular echogenicity in Baladi goats.Methods:Twelve Baladi goat bucks were randomly allocated into 2 groups and received an intravenous injection of either 0.7 IU/kg oxytocin or normal saline 0.9%.Venous blood samples were collected,and testicular blood flow Doppler parameters(i.e.,peak systolic velocity,end-diastolic velocity,time average maximum velocity,resistive index,and pulsatility index)were assessed for supratesticular arteries in the left and right testes immediately before(0),and at 5,30,60,and 120 min after injection.Results:Plasma concentrations of testosterone significantly decreased in the oxytocin group at 60 min post-treatment compared to the control group,whereas plasma concentrations of estradiol-17βwere not affected(P>0.05).Both resistive index and pulsatility index declined in the oxytocin group at 60 min post-treatment compared to the control group(P<0.05).Testicular pixel intensity increased at 30 min post-treatment in the oxytocin group compared to the control group(P<0.05).Conclusions:Oxytocin treatment significantly increases testicular blood flow and decreases plasma testosterone concentrations in male Baladi goats.

摘要： 速度是载体导航中必不可少的信息。GNSS时间差分载波相位(time difference carrier phase,TDCP)可求取历元间的高精度位移增量,进而可导出历元间的平均速度,但通常平均速度与瞬时速度的偏差较大;Doppler观测值可求取载体的瞬时速度,但观测噪声较大,精度较低。车载实测试验结果表明:该方法相比Doppler测速在X、Y、Z三个方向上的RMS分别提升44%、57%、46%,相比TDCP测速在三个方向上分别提升了40%、47%、50%,显著提高了测速的精度、可用性与鲁棒性。

摘要： Accurate assessment of the hemodynamic status is vital for appropriate management of patients with critical illness.As such,there has been a constant quest for reliable and non-invasive bedside tools to assess and monitor circulatory status in order to ensure end-organ perfusion.In the recent past,point of care ultrasonography(POCUS)has emerged as a valuable adjunct to physical examination in various specialties,which basically is a clinician-performed bedside ultrasound to answer focused questions.POCUS allows visualization of the internal anatomy and flow dynamics in real time,guiding apt interventions.While both arterial(forward flow)and venous(organ outflow or afterload)limbs of hemodynamic circuit are important for tissue perfusion,the venous side remains relatively under-explored.With recent data underscoring the deleterious consequences of iatrogenic volume overload,objective evaluation of venous congestion is gaining attention.Bedside Doppler ultrasound serves this purpose and aids in diagnosing and monitoring the congestion/venous blood flow pattern.In this article,we summarize the rationale for integrating this technology into routine care of patients with volume-related disorders,discuss the normal and abnormal waveforms,limitations,and future directions.

摘要： 速度是载体导航中必不可少的信息.GNSS时间差分载波相位(time difference carrier phase,TDCP)可求取历元间的高精度位移增量,进而可导出历元间的平均速度,但通常平均速度与瞬时速度的偏差较大;Doppler观测值可求取载体的瞬时速度,但观测噪声较大,精度较低.车载实测试验结果表明:该方法相比Doppler测速在X、Y、Z三个方向上的RMS分别提升44％、57％、46％,相比TDCP测速在三个方向上分别提升了40％、47％、50％,显著提高了测速的精度、可用性与鲁棒性.

摘要： 随着高速铁路近几年的迅猛发展,下一代交通技术也正渐渐突破桎梏.当前制约轮轨高铁发展的关键因素是稠密大气,真空管道高速飞行列车是一种新型轨道交通技术,它突破了介质限制,利用磁浮技术,可实现列车在接近真空的密闭管道中超高速(大于1 000 km/h)行驶.为解决列车运行在全封闭金属管道中,路边基站信号无法穿透管道壁与列车建立无线链路的问题,文中采用漏泄波导方式来实现管道内无线覆盖.通过特殊的漏泄波导缝隙设计,使得漏泄电磁波在管道腔体内以柱面波形式向列车辐射,从而有效抑制超高速带来的极高Doppler频移.在列车侧,提出一种车顶电磁介质透镜结构,漏泄波导辐射信号可透过透镜直达车内用户,从而实现车载结构与漏泄波导间有效的、无缝的上、下行通信.基于人工介质厚度与相位的定量关系来设计电磁透镜,使得电磁波透过透镜后从柱面波转化为平面波,从而实现更均匀的车厢内无线覆盖.

摘要： Shunt dysfunction is a major complication of transjugular intrahepatic portosystemic shunt(TIPS). Ultrasonography is a preferred method of shunt follow-up after TIPS, but some misjudgments can occur in cases of shunt dysfunction due to peculiarities of the VIATORR stent. Here we report one case and suggest that the first ultrasound evaluation for patients who received TIPS procedure with VIATORR stent should be performed one month after the procedure.

摘要： 水声通信环境比无线电通信环境复杂,尽管水声通信速率相对较低,提高水声通信的稳健性和吞吐率的难度远远高于无线电通信。笔者从水声通信环境物理意义出发,借鉴正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM),提出了OMFSK (Orthogonal Multiple Frequency Shift Keying, OMFSK),在计算机仿真基础上,又在浙江嵊泗海域验证了该方法的可行性。

摘要： 水声通信环境比无线电通信环境复杂,尽管水声通信速率相对较低,提高水声通信的稳健性和吞吐率的难度远远高于无线电通信。笔者从水声通信环境物理意义出发,借鉴正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM),提出了OMFSK (Orthogonal Multiple Frequency Shift Keying, OMFSK),在计算机仿真基础上,又在浙江嵊泗海域验证了该方法的可行性。

摘要： 水声通信环境比无线电通信环境复杂,尽管水声通信速率相对较低,提高水声通信的稳健性和吞吐率的难度远远高于无线电通信。笔者从水声通信环境物理意义出发,借鉴正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM),提出了OMFSK (Orthogonal Multiple Frequency Shift Keying, OMFSK),在计算机仿真基础上,又在浙江嵊泗海域验证了该方法的可行性。

摘要： 水声通信环境比无线电通信环境复杂,尽管水声通信速率相对较低,提高水声通信的稳健性和吞吐率的难度远远高于无线电通信。笔者从水声通信环境物理意义出发,借鉴正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM),提出了OMFSK (Orthogonal Multiple Frequency Shift Keying, OMFSK),在计算机仿真基础上,又在浙江嵊泗海域验证了该方法的可行性。

摘要： 水声通信环境比无线电通信环境复杂,尽管水声通信速率相对较低,提高水声通信的稳健性和吞吐率的难度远远高于无线电通信。笔者从水声通信环境物理意义出发,借鉴正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM),提出了OMFSK (Orthogonal Multiple Frequency Shift Keying, OMFSK),在计算机仿真基础上,又在浙江嵊泗海域验证了该方法的可行性。

摘要： 介绍运用超声Ｄｏｐｐｌｅｒ技术，用彩色显示出血流运动信息的二维图像的一种方法。

摘要： 介绍运用超声Ｄｏｐｐｌｅｒ技术，用彩色显示出血流运动信息的二维图像的一种方法。

摘要： 介绍运用超声Ｄｏｐｐｌｅｒ技术，用彩色显示出血流运动信息的二维图像的一种方法。

摘要： 本发明公开了一种基于Doppler传感网络的室内移动目标定位方法。包括多个无线雷达网络节点和主控节点，每个无线雷达网络节点包括基准时钟和Doppler雷达传感器，但之间没有建立时钟同步关系，由多个无线雷达网络节点的Doppler雷达传感器和主控节点组成无线链路；无线雷达网络节点探测得运动目标的多普勒信息，主控节点以时分复用的轮询方式通过无线链路读取各个无线雷达网络节点获取的多普勒信息，并融合得到运动目标在室内多径环境中的位置和位移信息。本发明具有多节点连接、低功耗传输、工作在多径室内环境，可以灵活配置传感器位置和数量、实现不同维度、不同移动目标的定位追踪的特点，具有很好的应用前景。

摘要： 针对脉冲噪声环境下分数阶傅里叶变换算法失效的问题，本发明利用一种非线性变换‑Sigmoid变换抑制脉冲噪声的干扰，并利用分数阶傅里叶变换的能量聚集特性，提出了一种对LFM脉冲雷达Doppler频移扩展因子和时延联合估计的新方法。首先将Sigmoid变换与分数阶傅里叶变换相结合，提出了基于sigmoid的分数阶傅里叶变换(Sigmoid‑FRFT)。接下来，通过Sigmoid‑FRFT峰值点搜索实现了多普勒频移扩展因子和时延的联合估计。该方法不需要噪声的先验知识，且对低信噪比噪声有较强的容忍性。实验结果表明该方法在脉冲噪声下具有较高的参数估计精度和较低的计算复杂度。

摘要： 本发明公开一种激光Doppler监测脉冲声辐射力剪切波定量估计HIFU损伤粘弹性的系统和方法，系统中：同步信号控制系统连接任意波形发生器和高速数据采集卡，任意波形发生器通过功率放大器、阻抗匹配网络连接高强度聚焦超声换能器；高强度聚焦超声换能器设置于水箱外部，被测仿体组织设置于水箱内部且连接一个三维移动装置；激光Doppler设备设置于水箱外部，且连接另一个三维移动装置；激光Doppler设备的输出端经高速数据采集卡连接PC机。本发明采用单脉冲作用于仿体组织，有效减少超声作用时间和超声辐射剂量；利用激光Doppler跟踪声辐射力剪切波，并使用2D‑FT的算法得到了剪切波波速和衰减系数，进一步解析出剪切弹性模量和剪切粘性系数，克服了现有SDUV方法的不足。

摘要： 本发明涉及一种基于修正Doppler观测值的GNSS精密测速方法，利用GNSS接收机输出的原始载波相位观测值对时间求导，得到导出Doppler观测值，导出Doppler观测值结合原始Doppler观测值，构造符号改正函数；当原始Doppler观测值与动态载体的实际运动产生的Doppler不相符时，利用所述符号改正函数对原始Doppler观测值进行判断和修正；利用经过修正的Doppler观测值进行测速，得到动态载体正确的运动速度。通过本发明，不必追究GNSS接收机内部信号处理过程，可确保在任何情况下利用GNSS的Doppler观测值计算动态载体的速度结果始终正确可靠，从而满足GNSS导航定位测速领域的技术需求，可为GNSS测速的硬件及软件产品提供技术支持。

摘要： 本发明公开了一种用于模拟测量恒星Doppler视向速度的实验装置与方法。该装置包含模拟光源、分束器、转盘、回射胶带、电机及其控制系统、光开关和光纤及耦合系统。用卤钨灯和碘蒸气吸收池模拟类似恒星谱线；转盘在电机及其控制系统的驱动下高速旋转，转盘倾斜放置用于产生需要的视向方向速度，转盘上的回射胶带沿视向方向使光束反转并耦合进入光纤，在出射端进入待测测量系统。光开关用于控制光束通过或不通过转盘从而实现发生或未发生Doppler频移两种状态。该实验装置实现了在实验室环境下模拟恒星Doppler视向速度，具有体积小、重量轻、速度连续可调等优点，适合作为在实验室条件下模拟恒星发生Doppler红移或蓝移情况的速度变化。

摘要： 本发明公开了一种应用于FMCW&Doppler双模式毫米波雷达系统的信号源，该信号源在FMCW模式下，能够输出24~26.65 GHz连续三角波输出；在Doppler模式下，能够输出24.125GHz单频点信号。本发明既能够为24G毫米波汽车雷达系统提供FMCW信号源，其典型的啁啾带宽为2.65 GHz，调制周期为1.272 ms，对应于5.6 cm的测距分辨率和0.15 m/s的测速分辨率；也能够为雷达系统提供Doppler信号源，其典型的测速分辨率是0.43 m/s。本发明两种模式融合设计，实现单芯片多功能化，有效降低成本。

摘要： 本发明公开一种顾及Doppler的北斗修正伪距单点定位方法、系统与设备，方法具体包括以下步骤：首先构建顾及Doppler的平滑伪距观测值表达式：其中，ω为平滑因子；λ为载波波长；P与分别为原始伪距观测值与平滑伪距观测值，单位为米，下标为历元标识；然后向所述平滑伪距观测值表达式中引入权重因子调整原始伪距观测值与平滑伪距观测值的权重，则有其中，η为权重因子；为修正伪距；充分发挥独立观测值Doppler的作用，削弱北斗原始伪距观测值的误差，抑制Doppler积分累计误差的影响，由于采样间隔一般不超过30秒，故权重因子η不会无限接近0，平滑伪距能发挥修正作用保证北斗伪距单点定位的精度与可靠性。

摘要： 本发明涉及一种应用于信道模拟器平台的实现Doppler谱生成处理的方法，包括以下步骤：信道模拟器生成均匀分布的随机数；信道模拟器根据目标Doppler谱的类型，确定各个参数的功率谱以及累积分布函数；信道模拟器将随机数作为累积分布函数的输入，计算得到相应参数的分布类型；信道模拟器根据不同参数的分布类型，计算得到最终的模拟器时域冲激响应。采用了本发明的应用于信道模拟器平台的实现Doppler谱生成处理的方法，适用于信道模拟器平台，用以建立信道模拟器中的基本信道模型。本发明利用Monte Carlo方法确定合成模拟器时域冲激响应的各个正弦波的相位、Doppler频率以及时延的分布，简化了实现Doppler谱的流程，降低了信道模拟器的计算复杂度。

摘要： 本发明公开了一种基于Doppler传感网络的室内移动目标定位方法。包括多个无线雷达网络节点和主控节点，每个无线雷达网络节点包括基准时钟和Doppler雷达传感器，但之间没有建立时钟同步关系，由多个无线雷达网络节点的Doppler雷达传感器和主控节点组成无线链路；无线雷达网络节点探测得运动目标的多普勒信息，主控节点以时分复用的轮询方式通过无线链路读取各个无线雷达网络节点获取的多普勒信息，并融合得到运动目标在室内多径环境中的位置和位移信息。本发明具有多节点连接、低功耗传输、工作在多径室内环境，可以灵活配置传感器位置和数量、实现不同维度、不同移动目标的定位追踪的特点，具有很好的应用前景。

摘要： 针对脉冲噪声环境下分数阶傅里叶变换算法失效的问题，本发明利用一种非线性变换‑Sigmoid变换抑制脉冲噪声的干扰，并利用分数阶傅里叶变换的能量聚集特性，提出了一种对LFM脉冲雷达Doppler频移扩展因子和时延联合估计的新方法。首先将Sigmoid变换与分数阶傅里叶变换相结合，提出了基于sigmoid的分数阶傅里叶变换(Sigmoid‑FRFT)。接下来，通过Sigmoid‑FRFT峰值点搜索实现了多普勒频移扩展因子和时延的联合估计。该方法不需要噪声的先验知识，且对低信噪比噪声有较强的容忍性。实验结果表明该方法在脉冲噪声下具有较高的参数估计精度和较低的计算复杂度。