Early prediction of myocardial viability after acute myocardial infarction by two-dimensional speckle tracking imaging

Background Identifying the transmural extent of myocardial necrosis and the degree of myocardial viability in acute myocardial infarction （AMI） is important clinically. The aim of this study was to assess myocardial viability using two-dimensional speckle tracking imaging （2D-STI） in patients with AMI. Methods 2D-STI was performed at initial presentation, three days, and six months after primary percutaneous coronary intervention （PCI） in 30 patients with AMI, who had a left anterior descending coronary artery （LAD） culprit lesion. In addition, 20 patients who had minimal stenotic lesions （〈 30% stenosis） on coronary angiography were also included in the control group. At six months dobutamine echocardiography was performed for viability assessment in seven segments of the LAD territory. According to the recovery of wall motion abnormality, segments were classified as viable or non-viable. Results A total of 131 segments were viable, and 44 were nonviable. Multivariate analysis revealed significant differences between the viable and nonviable segments in the peak systolic strain, the peak systolic strain rate at initial presentation, and peak systolic strain rate three days after primary PCI. Among these, the initial peak systolic strain rate had the highest predictive value for myocardial viability （hazard ratio： 31.22, P 〈 0.01）. Conclusions 2D-STI is feasible for assessing myocardial viability, and the peak systolic strain rate might be the most reliable predictor of myocardial viability in patients with AMI.

Coupling Analysis of Moment of Inertia & Dynamic on Optoelectronic Tracking Turntable

With photoelectric tracking system as the research object,based on the theorem of moment of momentum and Euler dynamic equation,Nonlinear biaxial coupling dynamic model of tracking turntable is established.Effects of moment of inertia coupling,speed coupling and the dynamic coupling between tracking turntable shafts were studied,the analytical relation between them was given in theory.Verify the change trend of theoretical model.And it provides the theory reference and model base,for the future design of the high precision tracking controller And control parameter selection and optimization.In the end,specific measures are made for structure optimization.

Light pen whole space coordinate measuring system based on a tracking turntable

Light pen coordinate measuring system(LPCMS)is a kind of portable coordinate measuring technique based on vision metrology.In classical LPCMS,the measuring range is limited to the camera’s field of view.To overcome this defect,a new LPCMS is designed in this paper to fulfil whole space coordinate measurement.The camera is installed on a turntable instead of a tripod,so that the camera can rotate to track the movement of the light pen.The new system can be applied to large scale onsite measurement,and therefore it notably extends the application of LPCMS.To guarantee the accuracy of the new system,a method to calibrate the parameters of the tracking turntable is also proposed.Fixing the light pen at a stationary position,and changing the azimuth angles of the turntable’s two shafts,so that the camera can capture the images of the light pen from different view angles.According to the invariant spatial relationship between the camera and the pedestal of the tracking turntable,a system of nonlinear equations can be established to solve the parameters of the turntable.Experimental results show that the whole space coordinate measuring accuracy of the new system can reach 0.25 mm within 10 m.It can be concluded that the newly designed system can significantly expand the measuring range of LPCMS without losing too much accuracy.

Value of myocardial function in children with Kawasaki disease by two-dimensional and three-dimensional ultrasound speckle tracking

Objective:To investigate the value of two-dimensional ultrasound speckle tracking(2D-STI)and three-dimensional ultrasound speckle tracking(3D-STI)in evaluating myocardial function in children with Kawasaki disease.Methods 92 children with Kawasaki disease admitted to our hospital from February 2017 to February 2019 were retrospectively analyzed.50 children who underwent 3D-STI examination were taken as observation group and 42 children who underwent 2D-STI examination were taken as control group.The left ventricular systolic function index,storage time and analysis time of the image,the diameter of coronary artery,the strain difference of left ventricular basal segment,middle segment,apical segment and whole segment were observed.Results The levels of left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),left ventricular myocardial mass(LVMI)in the observation group were higher than those in the control group(P<0.05),but there was no statistical difference in left ventricular ejection fraction(LVEF)between the two groups(P>0.05).The storage time and analysis time of the image in the observation group were significantly lower than those in the control group(P<0.05).The left coronary artery(LCA)and right coronary artery(RCA)in the observation group were higher than those in the control group(P<0.05).There was no statistical difference between left anterior descending(LAD)in the two groups(P>0.05).The longitudinal peak systolic strain(LS),circumferential peak systolic strain(CS)and radial peak systolic strain(RS)in the observation group were higher than those in the control group(P<0.05).The global longitudinal peak strain(GLS),global circumferential peak strain(GCS)and global radial peak strain(GRS)in the observation group were higher than those in the control group(P<0.05).LS and CS in the middle segment of the observation group were higher than those in the control group(P<0.05).Conclusions Compared with 2D-STI,3D-STI can objectively and accurately reflect the myocardial function of children with Kawasaki disease.

Evaluation of the Effect of Sigmoid-Shaped Interventricular Septum on Left Ventricular Systolic Function in Patients with Essential Hypertension by Two-Dimensional Speckle Tracking Echocardiography

Objective: To evaluate left ventricular regional and global systolic function by measuring left ventricular longitudinal strain (LS) in hypertensive patients with sigmoid-shaped interventricular septum (SIS) by two-dimensional speckle tracking (2D-STE);in order to explore whether the sigmoid-shaped interventricular septum affects the left ventricular systolic function in patients with hypertension. Methods: Routine echocardiographic parameters were measured in 30 hypertensive patients with SIS (SIS group) and 30 hypertensive patients without SIS (non-SIS group). The left ventricular segments and global LS were measured by 2D-STE, and the two sets of parameters were compared. Results: The value of the thickness of the basal segment of the interventricular septum (IVSBT), the thickness of the middle segment of the interventricular septum (IVSMT) and the ratio of the basal segment of the ventricular septum to the middle segment of the interventricular septum (IVSBT/IVSMT) in SIS group was higher than that in non-SIS group. However, the value of left ventricular outflow tract diameter (LVOTD) in SIS group was lower than that in non-SIS group. There was a significant difference between the two groups (all P Conclusion: SIS affects left ventricular regional systolic function of patients with hypertension. 2D-STE can early evaluate left ventricular longitudinal systolic function in hypertensive patients with SIS.

Value of two-dimensional speckle tracking imaging in quantitative assessment of left ventricular function in patients with OSAS

Objective: To research the clinical application of two-dimensional speckle tracking imaging (2D-STI) in quantitative assessment of left ventricular function in patients with obstructive sleep apnea-hypopnea syndrome (OSAS). Method: From July 2016 to December 2018, 86 patients with OSAS were selected as OSAS group. According to sleep apnea hypopnea index (AHI), they were divided into mild OSAS group (24 cases), moderate OSAS group (29 cases) and severe OSAS group (33 cases). Another 50 healthy volunteers who underwent physical examination in our hospital during the same period were selected as the control group. The left ventricular function of all patients was quantitatively assessed by 2D-STI. The left ventricular function of all patients was quantitatively assessed by 2D-STI. The results of routine echocardiography and left ventricular global strain parameters of the OSAS group, the control group and the OSAS patients with different severity were compared and analyzed. Result: There were no significant differences in the levels of left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDd), left ventricular end systolic diameter (LVESd) between the two groups and OSAS patients with different severity (P>0.05). The levels of IVST, LVPW and LVMI in the OSAS group were significantly higher than those in the control group, the levels of end-diastolic interventricular septal thickness (IVS), left ventricular posterior wall thickness (LVPW), left ventricular mass index (LVMI) in the severe OSAS group were significantly higher than those in the mild and moderate OSAS group, and the levels of IVST, LVPW and LVMI in the moderate OSAS group were significantly higher than those in the mild OSAS group, there were significant differences between groups (P<0.05). The levels of GLS, GRS and GCS in the OSAS group were significantly lower than those in the control group (P<0.05). GLS, GRS and GCS levels in the severe OSAS group were significantly lower than those in the mild OSAS group and the moderate OSAS group, while the levels of global longitudinal strain (GLS), global radial strain (GRS) and global circumferential strain (GCS) in the moderate OSAS group were significantly lower than those in the mild OSAS group (P<0.05). Conclusion: The left ventricular systolic function of OSAS patients is obviously impaired. Left ventricular function in OSAS patients can be assessed timely and accurately by two-dimensional speckle tracking imaging.

基于陀螺幅频泰勒级数展开的圆锥误差补偿方法

针对实际载体高动态运动环境中陀螺角速度经过滤波去噪且存在通带范围内增益不均匀的问题,导致传统等效旋转矢量迭代过程误差累积增加,提出一种基于陀螺频域特征的圆锥误差补偿算法。该方法构建了匹配陀螺频率特征的角速度输入函数,进而计算幅频旋转矢量增量与理想旋转矢量的差值,通过将特征函数在频域内展开泰勒级数,使频域特征项系数对应相等求解圆锥系数,补偿系数可以看作考虑频域特征后对理想系数的修正补偿量。仿真及实验结果表明,所提幅频特征补偿算法锥进轴漂移率由10^(-5)(°)/h降低为10^(-11)(°)/h,验证了算法可行性,最终在单轴转台进行位置跟踪实验,实时位置跟踪精度提高了10%,为高精度捷联惯性导航惯性器件与补偿优化算法提供了理论参考与实验基础。

二维激光跟踪转台轴系设计及动态形变误差修正

二维激光跟踪转台轴系结构的稳定性及动态形变误差补偿精度是激光跟踪仪实现高精度动态坐标测量的关键因素。为满足激光跟踪仪动态坐标测量高精度、高稳定的实际需求,本文研制了一套基于过定位双角接触轴承对轴系的二维转台。首先,基于转台性能指标要求开展二维转台轴系设计及精度分析;然后,基于所设计结构及现有装配工艺,结合弹性力学理论,开展转台动态形变误差形成机理分析,并通过刚柔耦合动力学仿真分析验证理论分析合理性。最后,提出基于共轭差动式光学自准直原理的轴系动态误差测量方法,完成对轴系稳定性和动态形变误差的测量补偿。实验结果表明:转台的动态形变误差重复性优于±0.6″,动态形变误差由补偿前的±7″降低为±1″,转台设计的稳定性和动态形变误差补偿精度满足设计需求。

搜索跟踪转台高分辨率图像的小目标检测技术研究

针对搜索跟踪转台高分辨率图像的要求,结合搜索跟踪转台的运动特点,提出了一种基于背景建模和YOLOv7的图像目标检测方法。首先,根据转台的运动参数,将提前采样的背景图像,由投影透视校正得到连续的背景图像,进而由背景差分法得到运动前景目标;其次,以YOLOv7作为该算法的目标检测器,结合转台背景信息半固定的特点,将背景图像作为训练数据进一步训练得到优化的网络参数;最后,搭建实验平台,建立了行人检测实验数据集。实验结果表明,本模型相比于原YOLOv7模型的召回率提升了6.56%,精确率提升了5.36%,可有效应用于高分辨率搜索跟踪转台的目标检测任务中。

激光发射系统轴头箱结构分析与优化

为提高轴头箱刚度,对激光发射系统的轴头箱进行结构优化。基于现有轴头箱结构,在光机装调完毕后,安装侧盖时会导致系统视轴与光轴之间的角度差变大,导致不满足使用要求。根据有限元法,对负载条件下的轴头箱进行静力学分析,得到其变形情况。相机箱体变形情况影响电视视轴指向,其角度变化可以直接用三角函数计算。反射镜法向量也会产生变化,采用最小二乘法对反射镜反射面的节点数据进行拟合,通过拟合数据获得反射镜的法向量,计算其光轴角度变化情况。通过优化轴头箱结构形式,改变轴头箱结构与箱体盖板之间的重量分配,减少装调完毕后需要增加的负载重量,从而改善跟瞄视轴与激光发射轴平行度的稳定性。根据有限元分析结果,优化后的轴头箱结构,安装侧盖对视轴与光轴之间角度差影响不超过1″。通过实验证明,优化后的轴头箱结构具有更好的刚度。

船用雷达稳定跟踪转台控制系统设计

针对某船用雷达对目标精确跟踪控制的需求,设计一种纵横摇稳定平台和方位-俯仰跟踪转台的四轴闭环控制系统。系统通过高精度光纤组合惯导,获得船舶纵摇、横摇、航向姿态和转台经度、纬度、高度等信息,一方面控制驱动纵横摇稳定平台相对船舶做反相运动来克服船舶摇摆,实现安装在其上的方位-俯仰转台保持大地水平;另一方面通过网络接收跟踪目标的经度、纬度、高度等信息,解算出目标相对转台的方位和俯仰角,实现目标的两轴跟踪。经试验验证,系统在船舶摇摆状态下能够实现对动态目标的稳定、精确跟踪,各技术指标满足系统要求,对解决类似问题有一定的指导意义。

车载光电跟踪系统跟踪转台的初始标定

提出了基于坐标变换的目标跟踪转台初始标定方法,用于提高车载光电跟踪系统的跟踪精度。首先,运用坐标变换理论,建立了转台精标定的数学模型,求解了转台标定的变换矩阵;然后,根据转台标定的实际需要,通过合理地分析和近似,推导了一种转台的粗标定方案;最后,将粗标定与精标定方法相结合对跟踪转台进行初始标定实验。实验结果表明,该标定方法提高了初始标定的效率,对大于等于10km的远距离目标,精标定之后的转台跟踪误差小于0.1°,完全满足车载光电跟踪系统的精度要求。该标定方法已在一批车载光电跟踪系统中得到了成功应用。

用于三轴转台的卫星跟踪策略

针对纬轴工作范围为±20°的三轴跟踪架结构不能跟踪半球空域内所有卫星的问题,本文研究了卫星跟踪原理,结合纬轴受限的三轴结构特点,推导出了三轴之间关系的公式,并由此仿真得出了STTA卫星跟踪策略算法。跟踪仰角70°以上的卫星时,采用方位轴定位式水平式跟踪,这种跟踪方式既利用了水平式结构保精度跟踪天顶附近目标的优势,又克服了地平式结构有天顶跟踪盲区问题;跟踪仰角70°以下的卫星时,采用方位轴随动式水平式跟踪,这种跟踪方式使地平式跟踪方式和水平式跟踪方式有机地结合起来,实现优势互补,达到了更为理想的跟踪效果。该跟踪策略不仅解决了三轴转台纬轴工作范围受限问题,而且能够捕获跟踪半球空域内所有卫星,并保证卫星全程在保精度跟踪范围内。最后设计了实验,证明了该跟踪策略算法的有效性和可行性。

机载光电转台的谐振分析及自适应滤波器设计

在深入分析光电跟踪转台特性的基础上,对光电转台进行了数学建模,并利用转台的转角变化信息,提出了一种基于角度信息的自适应前馈滤波算法。该算法在不改变机械结构和阻尼因素的条件下,有效地抑制了光电转台的机械谐振。实验结果证明:该算法在一个周期后,系统自动跟踪的最大跟踪误差提高了3′,是一种易于实现,设计操作简单,实效性好的自适应滤波算法,目前已成功运用到某机载光电对抗转台中,效果良好。

基于FPGA的光电跟踪控制系统设计

为了提高光电跟踪控制系统可靠性和实时性,设计了一种基于FPGA的控制系统。该控制系统以一块FPGA芯片为核心,主要完成传感器信号处理,控制算法实现,脉宽调制方波生成,与上位机通信等任务。采用Xilinx公司的ISE7.0平台进行开发,并用层次化和模块化的方式进行设计。实验结果表明这种设计方法使系统以比较低的成本获得了很高的处理速度,从而提高了系统的性能。

重复控制算法在转台伺服系统中的应用

针对转台伺服系统中周期性波动力矩扰动抑制问题,利用重复控制算法能以十分简单的控制器形式高精确度地完成跟踪或抑制周期性参考信号或扰动信号的优点,提出了一种基于扰动观测器的鲁棒学习控制算法。给出了基于扰动观测器的转台伺服系统结构图,并将重复控算法引入到基于扰动观测器的扰动补偿策略中。L2稳定性定理证明该方法保证了闭环系统的稳定性和对期望信号的渐近跟踪;仿真结果也表明,该方法较传统方法既有效地抑制了系统周期性波动力矩,又提高了系统运动曲线的跟踪性能。

精密光电跟踪转台的设计与伺服控制

以某型号电视制导导引头为背景,针对载体上光电跟踪系统的特点,设计研制了一种新型四轴精密光电跟踪转台。在介绍转台主要性能指标的基础上,从系统机械谐振、结构建模、元部件选型计算方面进行了详细分析和设计,给出了基于高速DSP控制器和数字滤波的复合闭环伺服控制策略和实现方案。实验测试结果达到预先制定的设计指标和精度要求,表明了系统设计方案的实用性和有效性。所设计转台能够在实验室条件下模拟弹、箭制导导引头和机载光电成像跟踪系统等的动力学特性和各种运动姿态,为实际系统的研制和改进提供重要参考依据和实验数据。

光电跟踪转台的控制模型辨识

针对大功率永磁同步电机驱动的光电跟踪转台,提出了一种基于特征系统实现算法的控制模型辨识方法。首先,根据永磁同步电机的矢量控制原理,对白噪声测试系统进行了系统配置;其次,采用功率谱密度函数的分析方法对系统的输入和输出数据序列进行了分析,得到了系统的频率响应函数;最后,通过特征系统实现算法对系统的马尔可夫参数进行了辨识,获得了光电跟踪转台的控制模型。实验结果表明:采用特征系统实现算法可以精确地辨识出光电跟踪转台的控制模型,该控制模型能够较好地反映系统的动态特性,为控制器算法的设计提供了理论依据,具有较好的实用性。

高精确度伺服转台控制系统中的扰动力矩补偿

摩擦力矩和电机波动力矩是影响高精确度伺服转台控制系统位置跟踪精确度的主要因素。针对系统中摩擦力矩和电机波动力矩等扰动力矩补偿问题,提出一种综合的扰动力矩补偿控制策略。基于摩擦观测器提出一种PD前馈控制方法,对系统中的动态摩擦力矩进行了补偿,并利用Lyapunov稳定性理论对所提出的方法进行了系统稳定性分析。结合基于重复控制器的扰动观测器进一步提出一种综合的扰动力矩补偿控制策略。一方面,摩擦补偿方法可以对系统中的摩擦力矩进行补偿;另一方面,插入的重复控制器可以很好地抑制系统中的周期性波动力矩,而扰动观测器则用来补偿重复控制及摩擦补偿时给系统带来的不确定性。仿真结果证明了所提出的方法的有效性。

卫星星间激光通信粗跟踪转台控制系统

为了满足卫星星间激光通信粗跟踪系统高的动态性能和稳态性能,针对普通PID控制存在阶跃响应超调量大、调节时间过长等问题,以永磁同步电动机为控制对象建立粗跟踪系统的三环控制模型,并进行matlab仿真分析。在普通PI控制的基础上提出一种自适应增益控制,为跟踪系统缩短调节时间改善超调等动态性能提供新的方法,在基于FPGA主控单元的控制下。地面实验表明,在187.25μrad(500码)阶跃信号的激励下,改进的自适应增益控制策略较普通PI控制,超调量由35.8%下降到10%,调节时间由100 ms缩短到70 ms,稳态精度保持在±2.247μrad(3码),控制性能得到了显著改善。在轨工况下,自适应增益控制策略能够实现星间激光通信跟踪转台的高精度控制,同时对其他高精度伺服系统设计具有借鉴意义。