An improved positioning model of deep-seafloor datum point at large incidence angle

The inhomogeneous sound speed in seawater causes refraction of sound waves,and the elimination of the refraction effect is essential to the accuracy of underwater acoustic positioning.The raytracing method is an indispensable tool for effectively handling problems.However,this method has a conflict between localization accuracy and computational quantity.The equivalent sound speed profile(ESSP)method uses a simple sound speed profile(SSP)instead of the actual complex SSP,which can improve positioning precision but with residual error.The residual error is especially non-negligible in deep water and at large beam incidence angles.By analyzing the residual error of the ESSP method through a simulation,an empirical formula of error is presented.The data collected in the sailing circle mode(large incidence angle)of the South China Sea are used for verification.The experiments show that compared to the ESSP method,the improved algorithm has higher positioning precision and is more efficient than the ray-tracing method.

Kappa angles in different positions in patients with myopia during LASIK

AIM： To investigate the difference in kappa angle between sitting and supine positions during laser-assisted in situ keratomileusis（LASIK）.·METHODS： A retrospective study was performed on395 eyes from 215 patients with myopia that received LASIK. Low, moderate, and high myopia groups were assigned according to diopters. The horizontal and vertical components of kappa angle in sitting position were measured before the operation, and in supine position during the operation. The data from the two positions were compared and the relationship between kappa angle and diopters were analyzed.· RESULTS： Two hundred and twenty-three eyes（56.5%） in sitting position and 343 eyes（86.8%） in supine position had positive kappa angles. There were no significant differences in horizontal and vertical components of kappa angle in the sitting position or horizontal components of kappa angle in the supine position between the three groups（P 〉0.05）. A significant difference in the vertical components of kappa angle in the supine position was seen in the three groups（P 〈0.01）. Differences in both horizontal and vertical components of kappa angles were significant between the sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angles（P 〈0.05） were found and vertical components of kappa angle in sitting and supine positions were negatively correlated with the degree of myopia（sitting position： r =-0.109; supine position： r =-0.172; P 〈0.05）.·CONCLUSION： There is a correlation in horizontal and vertical components of kappa angle in sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angle in sitting and supine positions till the end of the results. This result still needs further observation. Clinicians should take into account different postures when excimer laser surgery needs to be performed.

Effects of laser beam divergence angle on airborne LIDAR positioning errors

The influence of laser beam divergence angle on the positioning accuracy of scanning airborne light detection and ranging （LIDAR） is analyzed and simulated. Based on the data process and positioning principle of airborne LIDAR, the errors from pulse broadening induced by laser beam di vergence angle are modeled and qualitatively analyzed for different terrain surfaces. Simulated results of positioning errors and suggestions to reduce them are given for the flat surface, the downhill of slope surface, and the uphill surface.

Effect of body position on the pathogenesis of asymmetric primary open angle glaucoma

AIM： To explore the pathogenesis of asymmetric primary open angle glaucoma（POAG） in both eyes by comparing the intraocular pressure（IOP） of patients who sleep in different positions and to investigate the relationship between IOP variations and sleep positions.METHODS： One hundred and thirty-one patients with asymmetric POAG and forty-six healthy volunteers were enrolled. All participants completed a questionnaire that provided information about their sleep laterality. The cup disc ratio（C/D） and visual field defect established binocular asymmetry. The IOP of both eyes was measured using i Care parameters after the patients were asked to change body position. The ＂worse＂ and ＂better＂ eyes were identified according to the diagnosis, whereas the ＂dependent＂ and ＂independent＂ eyes were defined according to the lateral position. RESULTS： No significant difference in sleep laterality was observed between healthy people and patients with POAG（F=3.195, P=0.362）. Among the enrolled patients, the IOP of the dependent eye was always greater than that of the independent eye in the lateral position（P〈0.05）. In the patients with binocular asymmetric POAG, the questionnaire clearly showed that 85.7% of left side preferences were found their left eyes to be the worse eyes and the right eyes of 71.4% patients with a right side preference were the more serious. When the asymmetric C/D ratio was greater than or equal to 0.2, the worse eye of patients with POAG and a preferred sleeping position was the dependent eye（χ~2=16.762, P=0.001）.CONCLUSION： A higher IOP was measured in the dependent eye in the lateral position. The long-term tendency to choose a lateral sleeping position might lead the dependent eye to manifest more severe symptoms than the independent eye. Thus, the lateral sleeping position might be one cause of asymmetric POAG.

Dependence of epoch-wise two-way nested ANOVA estimates of variances of unmodeled effects present in relative GPS positioning on satellite elevation cutoff angle and PDOP mask

Impact of satellite elevation cutoff angle and position dilution of precision(PDOP)mask change on epoch-wise variance components of unmodeled effects that accompany relative Global Positioning System(GPS)positioning is presented herein.Data used for this study refer to the winter and summer periods of the years with minimal(2008)and maximal(2013)solar activity.These data were collected every 30 s in static mode,at two permanent GPS stations located in Montenegro,establishing a mediumdistance(116-km-long)baseline with a height difference of approximately 760 m between its endpoints.The study showed that changing satellite elevation cutoff angle,with a fixed PDOP mask,affects epochwise two-way nested ANOVA estimates of variances related to the‘far-field’multipath(considered as the nested factor herein)and the combined unmodeled effect of tropospheric and ionospheric refraction(considered as the nesting factor herein).However,changing of PDOP mask,with a fixed satellite elevation cutoff angle,doesn’t affect epoch-wise two-way nested ANOVA estimate of variance of the combined unmodeled effect of tropospheric and ionospheric refraction,but,generally,affects the estimate of variance of the‘far-field’multipath(possibly mixed with a part of a‘shorter-term’ionospheric refraction),which is especially pronounced for the summer period.It should also be noted that there is a significant influence of satellite elevation cutoff angle change on both epoch-wise horizontal and vertical position accuracy,only for the summer period,especially in the presence of maximal solar activity,while there is no significant impact of PDOP mask change on epoch-wise positional accuracy.

Accurate Source-Receiver Positioning Method for a High-Resolution Deep-Towed Multichannel Seismic Exploration System

The near-seabed multichannel seismic exploration systems have yielded remarkable successes in marine geological disaster assessment,marine gas hydrate investigation,and deep-sea mineral exploration owing to their high vertical and horizontal resolution.However,the quality of deep-towed seismic imaging hinges on accurate source-receiver positioning information.In light of existing technical problems,we propose a novel array geometry inversion method tailored for high-resolution deep-towed multichannel seismic exploration systems.This method is independent of the attitude and depth sensors along a deep-towed seismic streamer,accounting for variations in seawater velocity and seabed slope angle.Our approach decomposes the towed line array into multiline segments and characterizes its geometric shape using the line segment distance and pitch angle.Introducing optimization parameters for seawater velocity and seabed slope angle,we establish an objective function based on the model,yielding results that align with objective reality.Employing the particle swarm optimization algorithm enables synchronous acquisition of optimized inversion results for array geometry and seawater velocity.Experimental validation using theoretical models and practical data verifies that our approach effectively enhances source and receiver positioning inversion accuracy.The algorithm exhibits robust stability and reliability,addressing uncertainties in seismic traveltime picking and complex seabed topography conditions.

A Combined Antenna Array Deployment with High Positioning Accuracy and Low Angular Measurement Error

In this paper,an antenna array composed of circular array and orthogonal linear array is proposed by using the design of long and short baseline“orthogonal linear array”and the circular array ambiguity resolution design of multi-group baseline clustering.The effectiveness of the antenna array in this paper is verified by sufficient simulation and experiment.After the system deviation correction work,it is found that in the L/S/C/X frequency bands,the ambiguity resolution probability is high,and the phase difference system error between each channel is basically the same.The angle measurement error is less than 0.5°,and the positioning error is less than 2.5 km.Notably,as the center frequency increases,calibration consistency improves,and the calibration frequency points become applicable over a wider frequency range.At a center frequency of 11.5 GHz,the calibration frequency point bandwidth extends to 1200 MHz.This combined antenna array deployment holds significant promise for a wide range of applications in contemporary wireless communication systems.

Modified algorithm of combined GPS/GLONASS precise point positioning for applications in open-pit mines

A modified algorithm of combined GPS/GLONASS precise point positioning （GG-PPP） was developed by decreasing the number of unknowns to be estimated so that accurate position solutions can be achieved in the case of less number of visible satellites. The system time difference between GPS and GLONASS （STDGG） and zenith tropospheric delay （ZTD） values were firstly estimated in an open sky condition using the traditional GG-PPP algorithm. Then, they were used as a priori known values in the modified algorithm instead of estimating them as unknowns. The proposed algorithm was tested using observations collected at BJFS station in a simulated open-pit mine environment. The results show that the position filter converges much faster to a stable value in all three coordinate components using the modified algorithm than using the traditional algorithm. The modified algorithm achieves higher positioning accuracy as well. The accuracy improvement in the horizontal direction and vertical direction reaches 69% and 95% at a satellite elevation mask angle of 50°, respectively.

New System to Measure the Yaw and PitchAngles of Rocket in Launch Phase

Aim To describe a news system for measuring the and pitch angles of rocket during the launch phase Methods Optical system was to reflect the spot that represents the angular movement of rocket to the position sensitive detector that can convert analogue signal into digital one.Results Compared with conventional optical lever test system which had been applied to measure rocket attitude angle,the new system used the position sensitive detector to replace the screen and high-speed photographic instrumentation as grapher,which can avert photointerpretive data reduction and apply to field experiment more easily and pre- cisely .Conclusion Experimental results show that the test system can be used in measuring the yaw and pitch angles of rocket effectively.

Development of photon beam position feedback system based on two PBPMs at HLS

In this paper,in order to stabilize the position and angle of the light source point,a new photon beam position feedback system based on the Photon Beam Position Monitors was developed on Hefei Light Source,and used to correct the position drift and angle variation of the light source at the same time.On introducing the feedback principle,the transfer function matrix is calibrated,indicating that the new system is workable and effective.

Advances in the Clinical Application of Trendelenburg Position

The Trendelenburg position and reverse Trendelenburg position are frequently employed during lower abdominal surgery to achieve optimal surgical field visualization and complete exposure of the operative site, particularly under pneumoperitoneum conditions. However, these positions can have significant impacts on the patient’s physiological functions. This article overviews the historical background of Trendelenburg position and reverse Trendelenbury position, their effects on various physiological functions, recent advancements in their clinical applications, and strategies for preventing and managing associated complications.

Head Position of Patients with Right Hemisphere Damage during a Visual Search Task in a Large Field

Spatial neglect syndrome with cerebral lesions is characterized by the ina-bility to orient, report, or respond to relevant visual stimuli contralateral to the lesions. In this study, we investigated the pattern of horizontal visual search in a large space;this search was performed by patients with right hemisphere damage caused by cerebrovascular disease. The neck rotation angle and search time in each increment were continuously recorded during the task, and quantitative data of the measurements were collected. Head position during the visual search task in a large space (%) was then calculated. We set angular bands in increments of 5 degrees from the midline on the left and right sides, and calculated the total search time in each angular band. In patients with unilateral spatial neglect (USN), the search time in the angular band of 5 - 9 on the right side was significantly longer (with USN 16.7%, without USN 4.5%, t = 2.52, df = 16, p < 0.05). Furthermore, in patients with neglect in the leftmost end area in a large space, the search time was significantly shorter in the angular band of 1 - 4 degrees to the left (with neglect 13.1%, without neglect 23.7%, t = 2.13, df = 16, p < 0.05), and tended to be long in the angular band of 5 - 9 to the right. The neck rotation angle and pattern during the search task in a large field deviated slightly to the right, and the search time slightly to the left was short. We believe that these results support the rightward deviation of the search pattern and frame of USN patients.

An effective and safe gastric endoscopic submucosal dissection in the right lateral position using an inverted overtube

Previously, we reported the efficacy of a newly developed inverted overtube in shortening the hemostatic time and obtaining a clear endoscopic view in emergency endoscopic hemostasis. This device also helped us to perform gastric endoscopic submucosal dissection(ESD) more safely by changing the direction of gravity in the right lateral position. To perform a safe ESD, it is important to make an appropriate angle and distance between the electric knife and the gastric mucosa. In this position, the distance to gastric mucosa is reduced, and the angle of the electric knife changes from vertical to somewhat oblique, facilitating safer cutting.

Accurate Angle-of-Arrival Measurement Using Particle Swarm Optimization

As one of the major methods for location positioning, angle-of-arrival (AOA) estimation is a significant technology in radar, sonar, radio astronomy, and mobile communications. AOA measurements can be exploited to locate mobile units, enhance communication efficiency and network capacity, and support location-aided routing, dynamic network management, and many location-based services. In this paper, we propose an algorithm for AOA estimation in colored noise fields and harsh application scenarios. By modeling the unknown noise covariance as a linear combination of known weighting matrices, a maximum likelihood (ML) criterion is established, and a particle swarm optimization (PSO) paradigm is designed to optimize the cost function. Simulation results demonstrate that the paired estimator PSO-ML significantly outperforms other popular techniques and produces superior AOA estimates.

旋变二次谐波测角误差自校正

旋变幅值误差和正交误差在角速度频谱上表现为旋变转频的二次谐波,是旋变测角误差的主要来源,影响伺服系统角速度控制精度和稳定度。本文提出了一种基于特征频率参考的二次谐波误差自校正方法。首先,分析旋变测角误差产生的机理,获知其幅值误差和正交误差的互不相关性,并证明对旋变输出信号进行幅值调整和相位差调整可实现二次谐波误差校正。然后,在旋变和旋变数字信号转换器(Resolver-to-Digital Converter,RDC)之间设计基于比例放大的幅值校正器和基于交叉调节的相角校正器。最后,根据误差信号在线性控制系统中特征频率不变的特性,对伺服系统进行匀速控制,以角速度频谱中二次谐波频率的幅值为参考基准,分别调整幅值校正器和相角校正器,校正二次谐波误差。实验结果表明:本方法可将旋变二次谐波测角误差幅值降低78.5%,伺服系统速率波动量降低40.5%。本方法实现了旋变二次谐波测角误差的自校正,大幅提升了旋变的测角精度和伺服系统的转速控制稳定度。

基于二维混合式位置编码的高精度测角

针对具有精密旋转轴系类的高端制造装备或精密测量仪器,其旋转角度采用传统圆光栅难以消除偏心误差对测量角度精度的影响,提出了一种基于二维混合式位置编码的旋转角度高精度测量方法。该测角系统由一个二维混合式位置编码盘、两个CCD相机和远心镜头组成,二维混合式位置编码盘被固定在精密旋转轴系上以获得其旋转角度。然后,建立了测角模型并从数学上证明了测角精度与安装偏心无关。利用多齿分度台对已提出测角系统精度进行检测,测量角度误差在±1″。最后,利用已提出测量方法对直驱转台的角度定位精度进行测量,角度定位误差在±5″内。与传统圆光栅测角相比,该方法不需要考虑安装偏心误差对测角精度的影响,具有稳定性好、使用简单等特点,可用于角度定位误差的检测。

基于伤椎高度、Cobb角评估棘突与椎板外缘定位椎弓根技术治疗胸腰椎骨折的疗效

目的通过伤椎高度、Cobb角评估棘突与椎板外缘定位椎弓根技术研究治疗胸腰椎骨折的疗效。方法选择2017年9月至2020年9月在衡水市第四人民医院收治的胸腰椎骨折患者116例,其中男性61例,女性55例;年龄38~71岁,平均年龄48.59岁;骨折节段,L137例,L223例,L1121例,L1235例。按照数字表法将患者分为观察组58例和对照组58例,两组患者均行椎弓根技术治疗。对照组患者给予上关节突外缘垂直线与横突平分线交点(Magerl法)定位椎弓根钉。观察组患者给予棘突与椎板外缘定位椎弓根钉。对比两组患者的Oswestry功能障碍指数(ODI)、伤椎矢状面Cobb角及伤椎前缘高度压缩率、骨代谢、骨愈合、炎症反应、肿胀及疼痛程度。结果两组患者术前、术后1周、术后1年的ODI比较,差异无统计学意义(P>0.05)。术前、术后1周两组患者的伤椎矢状面Cobb角比较,差异无统计学意义(P>0.05)。术后1年观察组伤椎矢状面Cobb角低于对照组[(9.8±2.9)°vs(13.5±3.0)°。P<0.05]。术前、术后1周两组患者的伤椎前缘高度压缩率比较,差异无统计学意义(P>0.05)。术后1年对照组伤椎前缘高度压缩率高于观察组[(14.2±3.4)%vs(8.6±2.2)%。P<0.05]。观察组患者的血清碱性磷酸酶(ALP)、Ⅰ型前胶原羧基端前肽(PICP)及骨钙素(BGP)指标均高于对照组[(219.23±6.34)μg/L vs(182.54±5.17)μg/L、(112.72±2.18)μg/L vs(93.67±2.69)μg/L、(7.52±0.36)μg/L vs(4.21±0.14)μg/L。P<0.05]。观察组可溶性细胞间黏附分子-1(sLCAM-1)、胰岛素样生长因子-1(IGF-1)指标均高于对照组[(107.58±4.25)μg/L vs(92.12±4.19)μg/L、(296.57±8.04)μg/L vs(237.28±7.82)μg/L。P<0.05]。观察组患者肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)及白细胞介素-1(IL-1)指标均低于对照组[(1.20±0.27)μg/L vs(1.52±0.51)μg/L、(1.06±0.14)μg/L vs(1.35±0.28)μg/L、(0.98±0.27)μg/L vs(1.19±0.42)μg/L。P<0.05]。第1天、第5天、第10天、第15天、第20天两组患者的肿胀程度及疼痛评分均逐渐降低,除第1天观察组肿胀程度高于对照组外[(3.88±0.54)分vs(3.31±0.43)分。P<0.05],其他不同时间对照组疼痛评分及肿胀程度高于观察组(P<0.05)。结论棘突与椎板外缘定位椎弓根技术治疗胸腰椎骨折可降低患者的伤椎高度、Cobb角,提高骨代谢,降低炎症反应、肿胀及疼痛程度,促进骨愈合,临床疗效显著。

调整体位角度护理对极低出生体重儿胃食管反流和胃排空的影响

目的探讨不同体位角度下极低出生体重儿(VLBWI)的胃食管反流与胃排空情况,为规避VLBWI吸入风险提供参考。方法以2022年9月至2023年9月我院收治的120例VLBWI为研究对象,用随机数字表法分为3组,予以不同喂养体位护理方案。试验组40例,近似坐位(90°)喂养,喂养后近似坐位30 min+头高足低60°30 min+头高足低30°保持。对照1组40例,头高足低60°喂养,喂养后头高足低60°30 min+头高足低30°保持。对照2组40例,头高足低30°喂养,喂养后头高足低30°保持。喂养期间,统计3组溢乳/呕吐与呼吸暂停的发生例次,计算3组呼吸暂停与气管内呛咳的发生率,评价胃食管反流情况。统计3组胃残留、减量喂养与停喂的发生例次,评价胃排空情况。结果试验组溢乳/呕吐发生例次少于对照1组,溢乳/呕吐与呼吸暂停发生例次少于对照2组,呼吸暂停和气管内呛咳发生率低于对照2组(P<0.05)。试验组胃残留、减量喂养与停喂发生例次少于对照1组和对照2组,对照1组胃残留、减量喂养与停喂发生例次少于对照2组(P<0.05)。结论采用近似坐位喂养VLBWI,喂养后保持近似坐位30 min,再调至头高足低位60°保持30 min,最后降至头高足低30°并保持的体位护理方案,可以加快VLBWI胃排空,减少胃食管反流。

基于TOA与AOA算法的室内定位方法

为了解决传统室内定位技术成本较高、稳定性差以及难于部署等问题,提出一种将到达时间(time of arrival,TOA)与到达角(angle of arrival,AOA)相结合的室内定位系统.该系统由定位基站与被控定位单元组成,其特征在于使用对射式布置的超声波传感器获取定位基站与被控定位单元之间的距离特征,利用角度传感器获取被控定位单元相对于定位基站的角度特征,以单基站就实现了精确的室内定位过程.分析了该系统基本结构与原理,建立定位与控制模型,在一定范围内对其定点定位精度与跟随定位精度进行了实验验证.实验结果表明:该系统结构简单,易于安装布置,鲁棒性强,在测试范围内的最大定点定位误差不超过5 cm,跟随定位误差不超过15 cm.

不同角度俯卧位通气在急性呼吸窘迫综合征患者中的应用效果

目的评估不同角度俯卧位通气在急性呼吸窘迫综合征(ARDS)患者中的应用效果。方法本研究为一项前瞻性、随机、对照临床试验,纳入2021年7月至2023年6月广东省第二中医院重症医学科(ICU)收治的ARDS患者共96例,随机分为A组(0°俯卧位通气)、B组(30°俯卧位通气)、C组(45°俯卧位通气),每组32例。A组男19例,女13例;年龄(50.25±11.31)岁;体重指数(BMI)(23.42±3.16)kg/m^(2)。B组男17例,女15例;年龄(51.93±12.48)岁;BMI(22.72±4.15)kg/m^(2)。C组男20例,女12例;年龄(52.39±12.82)岁;BMI(24.76±4.31)kg/m^(2)。观察时间为5 d。A组患者每天持续0°俯卧位通气16 h,每2 h将其托起一次防止压力性损伤。B组:维持0°俯卧位2 h后,使用30°翻身垫将患者身体向左倾斜30°,维持2 h;然后向右倾斜30°,同样维持2 h;最后恢复至0°俯卧位,如此循环,直至完成16 h俯卧位通气。C组:维持0°俯卧位2 h后,使用45°翻身垫将患者身体向左倾斜45°,维持2 h;然后向右倾斜45°,同样维持2 h;最后恢复至0°俯卧位,如此循环,直至完成16 h俯卧位通气。比较3组氧合指标[氧合指数(PaO_(2)/FiO_(2))、动脉血氧饱和度(SaO_(2))、动脉血氧分压(PaO_(2))、动脉血二氧化碳分压(PaCO_(2))]、血流动力学指标[心率(HR)、平均动脉压(MAP)、中心静脉压(CVP)]、Murray肺损伤评分(MLIS)、急性生理学及慢性健康状况评价Ⅱ(APACHEⅡ)评分、多器官功能障碍综合征(MODS)评分的变化,观察压力性损伤发生率。采用单因素方差分析、LSD法、配对t检验、χ^(2)检验。结果俯卧位通气5 d后,3组PaO_(2)/FiO_(2)、SaO_(2)、PaO_(2)、PaCO_(2)均较通气前改善,且A组、B组改善幅度均优于C组(均P<0.05);俯卧位通气前和通气5 d后,3组HR、MAP、CVP差异均无统计学意义(均P>0.05);俯卧位通气5 d后,3组MLIS、APACHEⅡ、MODS评分均较通气前降低,且A组、B组均低于C组[(1.72±0.37)分比(1.54±0.16)分比(1.89±0.26)分、(11.02±2.69)分比(11.01±2.01)分比(12.87±2.06)分、(5.64±0.37)分比(5.34±0.67)分比(6.19±0.43)分](均P<0.05);B组和C组压力性损伤发生率低于A组[15.63%(5/32)比18.75%(6/32)比40.63%(13/32)](P<0.05)。结论不同角度俯卧位通气均可以改善ARDS患者氧合和减轻病情,其中30°俯卧位通气改善最明显,并且可以降低压力性损伤发生率。