不同能见度条件下飞机图象视觉识别效能的研究

本研究旨在探讨不同能见度时目标识别效能的变化规律，为制定保障在雾天安全飞行与着陆（着舰）的规定提供科学依据。利用自制的气雾箱模拟实验系统，录出5种能见度（0．20、0．22、0．34、0．41、1．09km）下5种飞机模型（B－5、F－6、F－7、F－8、A－5）的图象（共125幅）。模拟观察距离为200m。然后由54名飞行人员对录出的图象作辨认测试，记录其反应时和正确率。结果显示，记录图象时的能见度愈大，识别正确率愈高，反应时愈短。当能见度达0．34km以上时，平均目标识别率达96％以上，反应时接近1s。而能见度为0．22km时，识别率急剧下降到61％，反应时急剧增长到1．7s。本研究结果提示，不同能见度下视觉辨认的明显变化发生在能见度0.3km附近，能见度降到0．3km以下，将对飞行安全带来极大危害。     

全身振动对跟踪作业工效及视觉—运动反应的影响

为探讨全身振动对跟踪作业工效及视觉－运动反应的影响，对１７名健康男性青年进行了双重任务测试及追踪瞄准纸笔测试。结果表明：视觉－运动反应总正确率ＡＲ、靶刺激反应正确率ＴｓＡＲ，０．３ｇｚ振动暴露组较对照组显著降低，０．１５ｇｚ振动暴露组与对照组比较则变化不显著。追踪瞄准纸笔测试中，两振动暴露组与对照组比较，两项打点数之和及打点速度均显著降低。结论：２０Ｈｚ、０．３ｇｚ的全身振动暴露３０ｍｉｎ后，对跟     

运动对歼击机飞行员抗荷耐力影响的研究

目的 回顾性分析不同类型、强度、频率、时间的运动对歼击机飞行员抗荷耐力的影响,探索提高歼击机飞行员抗荷耐力的运动处方。方法 遴选121名在空军杭州特勤疗养中心进行航空医学鉴定的歼击机飞行员,通过问卷调查和实地验证了解其运动习惯,用抗荷抗缺氧检测仪检测其抗荷耐力,回顾性分析不同类型、强度、频率、时间的运动对其抗荷耐力的影响。结果 有氧运动可显著提高抗荷耐力,且不同强度、频率和时间组的差异有统计学意义（F=3.146、6.054、3.114,P<0.05）;与低强度（或低频率,或短时间）有氧运动组相比,中、高强度,中、高频率和较长、长时间有氧运动组抗荷耐力明显增高（P<0.05）;中、高强度有氧运动组间,中、高频率有氧运动组间,以及较长时间、长时间有氧运动组间抗荷耐力差异均无统计学意义（P>0.05）。无氧运动可明显提高抗荷耐力,且不同强度、频率和时间组的差异有统计学意义（F=22.461、3.742、3.416,P<0.05）;与低强度（或低频率,或短时间）无氧运动组相比,中、高强度,中、高频率和较长、长时间无氧运动组抗荷耐力均明显增高（P<0.05）;高强...     

海军舰载机飞行员的心理评估和选拔借鉴研究CSCD

随着我海军航母的快速发展,培养大批舰载机飞行人才成为战斗力生成的关键。研究表明,舰基飞行对飞行员的心理素质有着极高的要求。舰载机起降难度高、风险大,海上飞行环境恶劣以及飞行任务强度高等舰基飞行特点对舰载机飞行员认知能力、应激能力、空间定向、心理运动能力等心理能力的要求要远远高于普通陆基飞行员。国外研究表明,在所有海军航空事故中,超过70％的事故在某种程度上归因于飞行人员的人因素问题,     

近意识丧失：对战斗机飞行员飞行效能的考验CSCD

加速度所致意识丧失（G‐induced loss of con‐sciousness ,G‐LOC）是战斗机飞行员受到的最严重的威胁之一。世界上首例G‐LOC是在第一次世界大战中由英国发现的。美国则在1922年的一次飞机竞赛中首次报道出现 G‐LOC。第二次世界大战期间,飞行员作战飞行时屡有G‐LOC发生导致飞行事故。航空医学研究认为,G‐LOC是加速度力作用引起人体大脑缺氧,从而导致飞行员意识丧失,由此研发的战斗机飞行员气动抗荷服,有效地防护空中G‐LOC的发生。     

视觉和触觉信息对飞行员俯仰轴向操纵的效应

前言 大多数现代飞机的仪表是通过视觉向飞行员传达信息。为了降低飞行员工作负荷,海军航空航天医学研究所(NAMRL)开发了一种姿态显示装置。该装置用了从前未被利用的触觉感觉。即使无可见天地线或在视线暂短离开仪表板的时间里,陀螺驱动触觉     

人体前方平面上目标点拾取运动特性及工效研究

目的 研究人体上肢对前方平面不同区域目标点的拾取运动特性和工效.方法 设计并进行了目标拾取实验,得到了人体上肢拾取前方平面上目标点所需时间、速度、运动轨迹线长度、功率等实验数据.结果 通过实验分析,初步揭示了不同区域目标点的拾取运动特性存在较大的差异.结论 右利手者拾取前方平面上目标点时,左上区目标点的拾取运动工效最好,右下区目标点的拾取运动工效最差.     

海军高性能歼击机飞行员表象扫描加工水平研究

目的探讨飞行训练对飞行员表象扫描加工能力的影响。方法20名海军歼击机飞行员作为试验组，对照组为20名大学生及医师，在年龄、利手和文化程度上均与试验组相匹配。试验以反应时附加因素法研究范式测定，并以Kosslyn高水平视觉加工模型对表象扫描加工特性进行分析。结果除简单任务的反应时外，试验组与对照组相比在各表象扫描距离上的反应时和正确率均未表现出明显的优势。结论飞行员表象扫描加工的能力并不因系统的飞行训练而明显提高，提示该能力的可塑性较低。     

聋人与正常人枕叶视皮层对亮度敏感性的功能磁共振成像研究

目的　利用血氧水平依赖性功能磁共振成像 (BOLD fMRI)技术 ,探讨聋人在固定频率、不同亮度的点光源刺激下 ,枕叶视皮层的兴奋情况 ,并比较兴奋区的分布、范围、强度与正常人是否一致。方法　对 12例聋人和 15例正常人给予闪烁频率为 8Hz、亮度为 0 7、2 2、5 0 0、180 0lm的点光源刺激 ,同时应用GE 1 5TSignaHorizonLX超导型磁共振成像系统 ,采集其脑部的BOLD fMRI数据。通过AFNI软件进行统计分析得到脑功能活动的图像。结果　在 4种不同亮度的点光源刺激下 ,聋人与正常人的枕叶视皮层均有明显兴奋区 ,且主要兴奋区位于枕叶矩状裂周围的视皮层内 ;随着亮度的增加 ,聋人与正常人视皮层兴奋区内的活动像素数 (numberofactivatedpixels)显著增加 (F正常人 =4 2 7,P <0 0 5 ;F聋人 =6 41,P <0 0 5 ) ,且在较高亮度刺激下 ,聋人枕叶视皮层的兴奋性高于正常人 ,但两者差异无显著性意义 (F =2 17,P >0 0 5 ) ;聋人与正常人视皮层内所有兴奋像素的平均活动水平(activationlevel)随亮度的增加变化不大 ,而在 4种亮度刺激下均兴奋的像素的平均活动水平却随着亮度的增加而有较明显的增加 ,但无显著性差异 (F正常人 =0 79,P >0 0 5 ;F聋人 =1 6 ,P >0 0 5 )。结论聋人与正常人对亮度的基本反应特性是相     

The effect of visual field manipulations on standing balance control in people with multiple sclerosis

BackgroundMultiple sclerosis (MS) is associated with an increased risk of falls, degeneration of sensory organization, and possible increased reliance on vision for balance control.Research questionThe aim of this study was to assess differences in standing postural control between people with MS and age and sex matched controls during medial-lateral (ML) oscillations of the visual field, with and without blinders to the lower periphery.MethodsTen persons with MS (mean age 54.0 ± 5.3 years) and ten age and sex matched controls (mean age: 56.3 ± 6.0 years) participated in this study. Balance control was assessed while participants stood in a Christie Cave system while wearing stereoscopic glasses that projected an immersive forest scene. Visual conditions consisted of 2 m ML visual oscillations of the scene at five frequencies (0.0, 0.3, 0.6, 0.7 and 0.8 Hz) with and without blinders to block the lower periphery.Results and significanceThe results demonstrated that, in comparison to controls, participants with MS had a significantly larger center of pressure sway in both the ML and AP direction to ML visual oscillations. Additionally, participants with MS and controls both increased center of pressure frequency content to the visual oscillation frequency, while participants with MS also increased relative power at the visual oscillation frequency in the AP direction. Blinders of lower periphery reduced the percent power at the visual oscillation frequency in both groups and reduced overall sway in participants with MS during visual oscillations. Overall, results indicate that postural balance is sensitive to visual feedback in people with MS. The elicited AP sway to ML visual oscillation could reflect errors in visual processing for the control of balance, and decreased sway in response to blocking vision of the lower peripheral field could indicate an increased reliance on visual cues to maintain balance.     

The effects of visual cognitive tasks on landing stability and lower extremity injury risk in high-level soccer players

BackgroundVisual cognition plays a pivotal role in sports. It is widely recognized that there is an intriguing coupling that they could affect each other through interaction between visual cognition and motor control, but few studies linked the effects of visual cognitive tasks on landing stability to postural control and injury risk.Research questionWhether visual cognitive tasks affect the landing stability and lower limb injury risk of professional soccer players?MethodsThe current study used a three-dimensional Multiple Object Tracking (MOT) task to simulate visual cognitive difficulties experienced in soccer matches. Fifteen male high-level soccer athletes (height: 181.43 ± 7.36 cm, weight: 75.37 ± 10.67 kg, training years: 10.07 ± 2.98 yr) from our school team were recruited and completed a landing action from a high platform with and without MOT tasks. Vicon infrared high-speed motion capture system and three-dimensional force measuring platform were used to collect various outcomes simultaneously.ResultsThe Time to Stabilization (TTS) during landing was significantly prolonged, while the Medial-Lateral Stability Index (MLSI), Anterior-Posterior Stability (APSI), Dynamic Postural Index Stability Index (DPSI), the trajectory lengths, and envelope area of COP during landing were also increased during MOT dual-task.DiscussionThe decline of these indicators reflected the deterioration in postural stability and greater requirements for maintaining balance which could increase the risk of injury in soccer athletes. We advocate that adequate visual attention and visual information processing might play critical roles in maintaining dynamic balance through the supraspinal neural network.     

Effect of fatigue and the absence of visual feedback on shoulder motor control in an healthy population during a reaching task

IntroductionThe main role of the upper limb is to position the hand in order to carry out varied activities requiring coordinated multi-joint movement, which requires mobility and stability at the glenohumeral joint. This is made possible by the interaction between active and passive structures as well as the integration of information coming from multiple systems. This interaction can be compromised by factors such as muscle fatigue and lack of visual feedback, leading to decreased performance. Several studies have investigated their isolated effect without looking at their combined effect.ObjectiveTo measure the specific and the combined effects of shoulder muscles fatigue and of lack of visual feedback on shoulder motor control during a reaching task with the arm in an elevated position.Methods60 healthy participants were randomly assigned to one of four experimental groups: 1) control with visual feedback; 2) control without visual feedback; 3) fatigue with visual feedback; 4) fatigue without visual feedback. Subjects had to perform 10 trials of a reaching task in the KINARM robotic arm. Kinematic variables of interest were time taken to complete the task, final error, initial angle of deviation and area under curve. Non-parametric ANOVAs were used.ResultsAnalyses showed that there were statistically significant differences (p < 0,01) for the time taken to complete the task (1.15 s compared to 0.70 s), the area under the curve (0.015m² compared to 0.009m²) and the final error (0.025 m compared to 0,011 m) between those who had visual feedback and those who did not. No statistically significant fatigue or feedback X fatigue interaction effects were found for all kinematic variables.ConclusionFindings show that lack of visual feedback had an impact on the reaching task performance while fatigue did not. In addition, fatigue did not increase the effect of the lack of visual feedback.     

下肢动脉CT成像中不同对比剂注射方案与对比剂剂量的相关性研究

目的 比较下肢动脉CT成像中2种不同对比剂注射方案对对比剂剂量的影响.方法 收集临床上怀疑下肢动脉疾病行CTA检查的患者50例,随机分为A、B组,对比剂碘普罗胺(350 mg I/mL).A组注射流率4mL/s,对比剂用量1.2 mL/kg.B组第1期5 mL/s注射20 mL,第2期3mL/s注射剩余量;B组对比剂总量=1.2 mL/kg×体质量-4 mL/s×(B方案对比剂注射时间-A方案对比剂注射时间).对2组腹主动脉-髂动脉段、股动脉-腘动脉段、小腿动脉段、足背或足底动脉段4个动脉段图像质量进行评分;测量4个动脉段CT值,记录2组对比剂剂量.均进行独立样本t检验.结果 B组4个动脉段图像质量评分、平均CT值均低于A组,差异均无统计学意义(P＞0.05).A组和B组对比剂剂量为(89.08士11.45)mL和(72.61士10.34)mL,差异有统计学意义(P＜0.05).结论 对比剂流率5 mL/s+3 mL/s分期注射可在不影响图像质量的前提下降低下肢动脉CTA的对比剂用量.     

Effects of simulated peripheral visual field loss on the static postural control in young healthy adults

BackgroundIntegration of visual, vestibular, and proprioceptive sensations contributes to postural control. People with peripheral visual field loss have serious postural instability. However, the directional specificity of postural stability and sensory reweighting caused by gradual peripheral visual field loss remain unclear.Research questionWhat are the effects of peripheral visual field loss on static postural control?MethodsFifteen healthy young adults participated in this study. The participants were asked to stand quietly on a foam surface. Three conditions of virtual visual field loss (90°, 45°, and 15°) were provided by a head-mounted display, and ground reaction forces were collected using a force plate to calculate the displacements of the center of pressure (COP).ResultsThe root mean square (RMS), mean velocity, and 95% ellipse area of COP displacements in the horizontal plane increased, and RMS in the anteroposterior (AP) direction was unchanged under the smallest visual field condition compared to the largest one. The power spectrum density of COP displacements in the low-frequency band was decreased and that in the medium-frequency band was increased in the AP direction.SignificanceDuring quiet standing of young healthy adults with peripheral visual field loss, increased peripheral visual field loss resulted in lower postural stability. Postural stability in the AP direction was maintained contrary to the functional sensitivity hypothesis. Peripheral visual field loss reduced the weighting of the visual input and increased that of the vestibular input in the AP direction to maintain equilibrium.     

Contrast timing in computed tomography: effect of different contrast media concentrations on bolus geometry

Objective

To assess the effect of low-osmolar, monomeric contrast media with different iodine concentrations on bolus shape in aortic CT angiography.

Materials and methods

Repeated sequential computed tomography scanning of the descending aorta of eight beagle dogs (5 male, 12.7 ± 3.1 kg) was performed without table movement with a standardized CT scan protocol. Iopromide 300 (300 mg I/mL), iopromide 370 (370 mg I/mL) and iomeprol 400 (400 mg I/mL) were administered via a foreleg vein with an identical iodine delivery rate of 1.2 g I/s and a total iodine dose of 300 mg I/kg body weight. Time-enhancement curves were computed and analyzed.

Results

Iopromide 300 showed the highest peak enhancement (445.2 ± 89.1 HU), steepest up-slope (104.2 ± 17.5 HU/s) and smallest full width at half maximum (FWHM; 5.8 ± 1.0 s). Peak enhancement, duration of FWHM, enhancement at FWHM and up-slope differed significantly between iopromide 300 and iomeprol 400 (p < 0.05). Except for enhancement at FWHM there were no significant differences between iopromide 300 and iopromide 370 and iopromide 370 and iomeprol 400 (p > 0.05).

Conclusions

Low viscous iopromide 300 results in a better defined bolus with a significantly higher peak enhancement, steeper up-slope and smaller FWHM when compared to iomeprol 400. These characteristics potentially affect contrast timing.