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Frontiers of Optoelectronics 2015年第2期8卷 170-176页

作者： jian gao Xiao PENG Peng LI Zhihua DING Junle QU Hanben NIU Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic Engineering Shenzhen University Shenzhen 518060 China State Key Laboratory of Modem Optical Instrumentation Department of Optical Engineering Zhejiang University Hangzhou 310027 China

Doppler optical coherence tomography or optical Doppler tomography （ODT） has been demonstrated to spatially localize flow velocity mapping as well as to obtain images of microstructure of samples simulta- neously. In recent decades, spectral domain Doppler optical coherence tomography （OCT） has been applied to observe three-dimensional （3D） vascular distribution. In this study, we developed a spectral domain optical coherence tomography system （SD-OCT） using super luminescent diode （SLD） as light source. The center wavelength of SLD is 835 nm with a 45-nm bandwidth. Theoretically, the transverse resolution, axial resolution and penetration depth of this SD-OCT system are 6.13 μm, 6.84 μm and 3.62 mm, respectively. By imaging mouse model with dorsal skin window chamber, we obtained a series of real-time OCT images and reconstructed 3D images of the specific area inside the dorsal skin window chamber by Amira. As a result, we can obtain the clear and complex distribution images of blood vessels of mouse model.

关键词： optical coherence tomography (OCT) mouse,dorsal skin window chamber vascular distribution

Prevalence of low back pain among soldiers at an army base

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Chinese Medical Journal 2013年第4期126卷 679-682页

作者： HOU Zhen-hai SHI jian-guo YE Hong NI Zhi-ming YAO Jun ZHENG Long-bao LIU Zhi-rong gao Ying WANG jian Department of Orthopedics the 117th People's Liberation Army Hospital Hangzhou Zhejiang 310004 China Institute of Sports Science and Technology Zhejiang University Hangzhou Zhejiang 310010 China

Background Low back pain （LBP） is a major medical and social problem among working populations and is associated with high medical expense, loss of productivity, and disability. The aim of this study is to investigate the prevalence of LBP among soldiers and evaluate the possible causative factors in military training. The results may provide an insight into changes needed in military training that will reduce the occurrence of LBP among soldiers. Methods A cross-sectional survey was conducted in a group of young soldiers in China to estimate the prevalence of LBP and evaluate possible causative factors in military training. Results The survey was distributed to 1659 soldiers, of whom 1624 responded. LBP was reported by 425 of the 1624 （26.2%） soldiers. The prevalence of LBP was higher in the armored force （51.3%） than in the artillery （27.5%） or infantry （11.9%）. A multivariate logical regression analysis identified night training, 5 km cross-country race, and grenade-throwing training as military training risk factors for LBP. Conclusions The relatively high incidence of LBP among soldiers was related to night training, 5 km racing, and grenade throwing. Modifications in these training methods should enhance the health of recruits and lower the incidence of LBP.

关键词： soldiers back pain, low physical fitness questionnaires risk factors

Accuracy of multi-echo Dixon sequence in quantification of hepatic steatosis in Chinese children and adolescents

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World Journal of Gastroenterology 2019年第12期25卷 1513-1523页

作者： Yu-Zhen Zhao Yun-Gen Gan jian-Li Zhou Jia-Qi Liu Wei-Guo Cao Shu-Mei Cheng Da-Ming Bai Meng-Zhu Wang Fang-Qin gao Shao-Ming Zhou Department of Gastroenterology Shenzhen Children's Hospital Department of Radiology Shenzhen Children's Hospital Department of Physical Examination Futian District Maternity and Child Healthcare Hospital Department of MR Scientific Marketing Siemens Healthineers Department of MR Clinical Marketing Siemens Healthineers

BACKGROUND Nonalcoholic fatty liver disease(NAFLD) is currently the outstanding cause of chronic liver disease in children and adolescents, especially in overweight and obese groups. Liver biopsy is the reference standard to diagnose NAFLD but invasive, thus it is not the best choice in clinical diagnosis and *** resonance(MR) is widely used in clinical trials to noninvasively quantify liver fat content in adults and children in foreign countries. While currently, it is rarely used in Chinese children and adolescents. We postulated that quantifying hepatic steatosis by MR could be extended to children and adolescents in *** To investigate the accuracy of MR imaging(MRI) in quantifying liver fat with MR spectroscopy(MRS) as a reference. A secondary goal was to assess the prevalence of NAFLD in overweight and obese Chinese children and *** were 86 children and adolescents enrolled in this study, including 65 overweight and obese children and 21 healthy children. The participants underwent MRI and MRS. MRI and MRS were performed using multi-echo Dixon and HISTO sequences, respectively, to calculate hepatic proton density fat fraction(PDFF). Hepatic steatosis was diagnosed using MRS-PDFF > 5% as the threshold. Spearman's analysis was used to evaluate the correlation between MRI and MRS. The agreement between these two methods was assessed by BlandAltman *** The MRI-PDFF in the MRS region of interest and the entire liver was 9.9% ±10.3% with a range of 0.3%-39.9%, and 10.6% ± 9.4% with a range of 1.9%-38.9%,respectively. The MRS-PDFF was 9.1% ± 10.0%, with a range of 0.5%-37.8%. The incidence of hepatic steatosis detected by MRS-PDFF was 46.5%(40/86) of all participants, all of whom belonged to the overweight and obese ***'s analysis indicated an excellent correlation between multi-echo Dixon and MRS(r > 0.9, P < 0.01). Bland-Altman analysis also demonstrated a good agreement between these two ***

关键词： Nonalcoholic fatty liver disease Magnetic resonance imaging Magnetic resonance spectroscopy Children and adolescents Hepatic steatosis

Determination of cut-off time of accelerated aging test under temperature stress for LED lamps

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Frontiers of Information Technology & Electronic Engineering 2017年第8期18卷 1197-1204页

作者： jian HAO Lei JING Hong-liang KE Yao WANG Qun gao Xiao-xun WANG Qiang SUN Zhi-jun XU University of Chinese Academy of Sciences Beijing 100049 China Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of Physics CAST Lanzhou 730000 China Opto_Electronics Technology Center Changchun Institute of Optics Fine Mechanics and Physics Chinese .4cademy of Sciences Changchun 130033 China

To acquire a rational minimum cut-off time and the precision of lifetime prediction with respect to cut-off time for the accelerated aging test of LED lamps, fifth-order moving average error estimation is adopted in this paper. Eighteen LED lamps from the same batch are selected for two accelerated aging tests, with 10 samples at 80 ℃ and eight samples at 85 ℃. First, the accelerated lifetime of each lamp is acquired by exponential fitting of the lumen maintenances of the lamp for a certain cut-offtime With the acquired lifetimes of all lamps, the two-parameter Weibull distribution of the failure probability is obtained, and the medium lifetime is calculated. Then, the precision of the medium lifetime prediction for different cut-off times is obtained by moving average error estimation. It is shown that there exists a minimum cut-off time for the accelerated aging test, which can be determined by the variation of the moving average error versus the cut-offtime. When the cut-off time is less than this value, the lifetime estimation is irrational. For a given cut-off time, the precision of lifetime prediction can be computed by average error evaluation, and the error of lifetime estimation decreases gradually as the cut-off time- increases. The minimum cut-off time and medium lifetime of LED lamps are both sensitive to thermal stress. The minimum cut-off time is 1104 h with the lifetime esti- mation error of 1.15% for the test at 80 ~C, and 936 h with the lifetime estimation error of 1.24% for the test at 85 ℃. With the lifetime estimation error of about 0.46%, the median lifetimes are 7310 h and 4598 h for the tests at 80 ℃ and 85℃, respectively.

关键词： LED lamp Accelerated aging test Medium lifetime Moving average error

基于GOMP及其改进的OFDM系统稀疏信道估计

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北京理工大学学报 2016年第9期36卷 956-959页

作者：高飞彭云柯薛艳明北京理工大学信息与电子学院北京100081

研究在正交频分复用(OFDM)系统的稀疏信道估计问题.由于在许多通信系统中信道具有稀疏性,因此可以把信道估计问题转化为稀疏信号的恢复问题,应用压缩感知理论求解,把现有的恢复算法——广义正交匹配追踪算法(GOMP)运用到信道估计中,并... 详细信息

研究在正交频分复用(OFDM)系统的稀疏信道估计问题.由于在许多通信系统中信道具有稀疏性,因此可以把信道估计问题转化为稀疏信号的恢复问题,应用压缩感知理论求解,把现有的恢复算法——广义正交匹配追踪算法(GOMP)运用到信道估计中,并对它加以改进.仿真结果表明,与广义正交匹配追踪算法(GOMP)相比,正交匹配追踪算法(OMP)运行时间少,计算复杂度低,但是估计的最小均方误差略差.为了进一步提高该算法的性能,提出了改进的广义正交匹配追踪算法,性能得到了较大的提高.

关键词：正交频分复用信道估计压缩感知正交匹配追踪

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不对称非线性蔡氏电路产生的混沌现象分析

系统工程与电子技术 2007年第12期29卷 2029-2031页

作者：王育飞姜建国上海交通大学电气工程系上海200240

为了更确切地描述实际系统中的混沌现象,提出了一种变形蔡氏电路,它含有一个不对称非线性阻性元件。对该电路进行了深入的数学分析;并在MATLAB环境下,对其产生的混沌现象进行了仿真分析。分析结果表明:改变电路中的线性电阻值R,可以观... 详细信息

为了更确切地描述实际系统中的混沌现象,提出了一种变形蔡氏电路,它含有一个不对称非线性阻性元件。对该电路进行了深入的数学分析;并在MATLAB环境下,对其产生的混沌现象进行了仿真分析。分析结果表明:改变电路中的线性电阻值R,可以观察到直流平衡态、Hopf分岔、倍周期分岔、单涡卷混沌吸引子、周期性窗口和不对称双涡卷混沌吸引子等非线性动力学行为;混沌系统对初始条件极其敏感;不对称非线性蔡氏电路有其特殊的性质。

关键词：不对称非线性阻性元件蔡氏电路混沌

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部分参考型图像质量的模糊分类评价

西安电子科技大学学报 2013年第5期40卷 200-204页

作者：侯伟龙何立火高飞西安电子科技大学电子工程学院陕西西安710071

图像质量的客观评价是图像处理领域中的一个重要分支.其评价指标可以作为一种测度或者准则用来校准图像处理系统,或用于图像处理算法的优化及参数的优选.部分参考型图像质量客观评价方法已经成为图像质量评价领域研究的热点之一.考虑到... 详细信息

图像质量的客观评价是图像处理领域中的一个重要分支.其评价指标可以作为一种测度或者准则用来校准图像处理系统,或用于图像处理算法的优化及参数的优选.部分参考型图像质量客观评价方法已经成为图像质量评价领域研究的热点之一.考虑到人眼对图像质量感知的模糊性,将图像质量空间划分为若干模糊集,利用自然场景统计特征,将图像质量评价问题转化为模糊分类问题,提出了一种快速、有效的部分参考型图像质量评价方法.该方法与经典的部分参考型图像质量评价方法相比,主观感知的相关系数平均提高,计算代价显著降低,与人类主观感知有很好的一致性.

关键词：图像质量评价部分参考型模糊分类

高浓度氩气稀释气体爆轰波临界管径和临界间距关系

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爆炸与冲击 2015年第4期35卷 603-608页

作者：喻健良高远闫兴清高伟大连理工大学化工机械学院辽宁大连116024

建立圆管及环形管道系统研究临近极限下爆轰波在管道内传播失效机理。选用C2H2+2.5O2+70%Ar气体,采用光纤探针测量爆轰波在管道内传播速度,用烟迹法记录管道内爆轰波胞格结构。结果表明:初始压力远大于爆轰极限压力时,爆轰波在管道内以... 详细信息

建立圆管及环形管道系统研究临近极限下爆轰波在管道内传播失效机理。选用C2H2+2.5O2+70%Ar气体,采用光纤探针测量爆轰波在管道内传播速度,用烟迹法记录管道内爆轰波胞格结构。结果表明:初始压力远大于爆轰极限压力时,爆轰波在管道内以稳定速度传播;随着初始压力的减小,爆轰波速度逐渐降低;当初始压力一定时,爆轰波速度随着管道尺寸的减小而逐渐减小;当初始压力达到临界压力时,爆轰波在进入到管道内后其速度会逐渐衰减直至爆轰波完全失效。对于不同几何尺寸的圆管与环管,通过引入无量纲参数d/λ及w/λ(d为圆管管径,w为环管间距,λ为爆轰胞格尺寸)得出,爆轰波在管道内传播的临界圆管直径为环形间距的2倍,与理论模型结果相吻合,验证了稳态气体基于爆轰波波面曲率的失效机理。

关键词：爆炸力学爆轰极限临界直径临界间距爆轰波波面曲率

基于压缩感知的OFDM稀疏信道估计导频优化算法

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北京理工大学学报 2017年第5期37卷 511-514页

作者：薛艳明彭云柯高飞北京理工大学信息与电子学院北京100081

研究了在正交频分复用(OFDM)系统中基于压缩感知信道估计的导频图案设计问题.为了优化信道估计的性能,提出了优化算法,在基于压缩感知的测量矩阵互相关最小化准则的基础上,通过增大随机生成数进行分组,分别计算每组的互相关值,再进行比... 详细信息

研究了在正交频分复用(OFDM)系统中基于压缩感知信道估计的导频图案设计问题.为了优化信道估计的性能,提出了优化算法,在基于压缩感知的测量矩阵互相关最小化准则的基础上,通过增大随机生成数进行分组,分别计算每组的互相关值,再进行比较求互相关的最大值从而获得导频图案.仿真结果表明,与使用基于测量矩阵互相关最小化准则的导频图案相比,该优化算法得到的信道估计的最小均方误差要低30%.

关键词：正交频分复用压缩感知信道估计导频

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船舶蒸汽系统管道仿真方法研究

系统仿真学报 2006年第4期18卷 835-837页

作者：田兆斐张志俭哈尔滨工程大学核科学与技术学院核动力仿真研究中心黑龙江哈尔滨150001

根据船舶饱和蒸汽系统管道的工作特点和结构特点,将复杂的蒸汽管网分为大直径蒸汽管道和小直径蒸汽管网两类仿真对象,根据质量守恒、能量守恒定律针对这两类仿真对象分别建立了两相箱体模型和流体网络模型。考虑了流体网络中网络节点与... 详细信息

根据船舶饱和蒸汽系统管道的工作特点和结构特点,将复杂的蒸汽管网分为大直径蒸汽管道和小直径蒸汽管网两类仿真对象,根据质量守恒、能量守恒定律针对这两类仿真对象分别建立了两相箱体模型和流体网络模型。考虑了流体网络中网络节点与外界环境的散热,提出了流体网络节点压力、温度、焓的修正方法。在某核动力装置模拟器上进行的仿真实验表明,该模型能够较好地反映船舶饱和蒸汽系统管道运行的动态特性。

关键词：蒸汽系统两相箱体模型流体网络模型船舶仿真