首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 9 毫秒
1.
吕鹏涛  张娟  支高飞 《应用声学》2015,23(11):10-10
为提高智能车对多车道的实际道路车辆行驶环境的适应性,提出了一种基于三车道模型的车辆检测方法。方法在预处理的基础上利用极角及位置约束的Hough变换得到可能的车道线信息并利用消失点对车道线进行筛选;利用三车道四线模型对车道线进行匹配;对于每条车道,分别利用车辆灰度信息对车道线内车辆进行识别,并利用视频的连贯性对车辆识别结果进行修正并跟踪车辆。该算法通过对车道线的二次筛选,提高了三车道模型的准确率,进一步提高了对于不同车道车辆识别的正确率。实验结果表明,在结构化道路上,对于不同路况,算法均具有较好的实时性和鲁棒性。  相似文献   

2.
于劲松  刘浩  张平  廖灿星  李芳亮 《应用声学》2014,22(6):1835-1838
针对健康管理智能算法与推理模型性能的验证与评估需求,设计了一种航空机电作动器健康管理验证系统;通过分析航空机电作动器的故障机理,提出了电机、控制器、齿轮减速器的数学建模方法和对应的主要失效模式的故障注入方法,设计了验证系统硬件平台、基于组件模式的通用软件运行环境及支持实时显示功能的验证与评估模块;仿真结果表明,该平台能够支持各种健康管理算法与系统模型的加载和调用,并能够实现验证与评估信息的在线显示。  相似文献   

3.
As a variant of Single-Shot Parameter Assessment by Retrieval from Signal Encoding, Velocity Single-Shot Parameter Assessment by Retrieval from Signal Encoding, a single-shot imaging method, has been developed to realize fast and straightforward flow quantification by solving inverse problems. A robust signal model, including its local magnetization and its phase evolution during signaling (resulting in a more precise representation of the sampled signal) is described here. Magnitude, velocity, relaxation rate and frequency information can be retrieved without any extra reference image acquisitions, as demonstrated by phantom studies. In the presence of stationary background, retrieved magnitude maps and velocity maps show results comparable to those obtained by phase-contrast methods (r>.99, P=.005), even with brief single-shot 70-ms acquisition.  相似文献   

4.
Quality assessment of stitched images is an important element of many virtual reality and remote sensing applications where the panoramic images may be used as a background as well as for navigation purposes. The quality of stitched images may be decreased by several factors, including geometric distortions, ghosting, blurring, and color distortions. Nevertheless, the specificity of such distortions is different than those typical for general-purpose image quality assessment. Therefore, the necessity of the development of new objective image quality metrics for such type of emerging applications becomes obvious. The method proposed in the paper is based on the combination of features used in some recently proposed metrics with the results of the local and global image entropy analysis. The results obtained applying the proposed combined metric have been verified using the ISIQA database, containing 264 stitched images of 26 scenes together with the respective subjective Mean Opinion Scores, leading to a significant increase of its correlation with subjective evaluation results.  相似文献   

5.
利用近红外光谱技术对354个废旧涤/棉混纺织物进行研究,通过偏最小二乘法(partial least squares ,PLS )和定性鉴别系数建立了不同光谱特征的涤/棉混纺织物近红外定性分析模型。染色涤/棉混纺织物N IR光谱主要有两大类,一类具有正常涤/棉光谱特征,另一类光谱由于样本中染料、颜料和消光剂等化学助剂的影响,使光谱谱线成斜线,失去其光谱特征。如以全部样本建模,模型识别率较低。故将样本分为两类:斜线光谱样本和正常光谱样本,分别建立NIR定性分析模型。NIR定性分析模型建立后,根据验证结果分别对建模的谱区、预处理方法和主因子数进行优化,以提高模型的稳健性和可靠性。结果表明,样本分别建模后,模型的识别率大大提高,用验证集样本进行内部验证,正常光谱和斜线光谱所建模型的识别率均达99%,其校正集相关系数 RC 均为0.991,验证集相关系数 RP 分别为0.983和0.984、校正标准差S EC分别为0.887和0.453、预测标准差SEP分别为1.131和0.573。用150个界外样本分别对正常光谱样本模型和斜线光谱样本模型进行外部预测检验,模型识别率分别达91.33%和88.00%,表明所建NIR定性分析模型能够较好地在回收现场进行涤/棉混纺织物的鉴别。  相似文献   

6.
从全国24个省(市)收集到222个秸秆样品,包括172个稻秸样品和50个麦秸样品。采用近红外光谱技术,结合主成分回归、偏最小二乘回归和改进的偏最小二乘回归建立了秸秆热值的定量分析校正模型。近红外光谱模型的建立与优化过程中使用了不同的散射校正方法和光谱导数处理来帮助改善模型精度。对得到的54个模型采用统计学的方法分析外部验证的结果,通过比较外部验证的系统偏差(Bias)和Bias校正的预测标准差(SEP(C)),考察了不同光谱预处理和回归方法对秸秆热值的近红外模型预测性能的影响。结果表明:近红外光谱技术能够快速、准确地分析秸秆的热值,模型的SEP(C)在134~178 J·g-1之间;对外部验证结果的统计分析,能够有效地选择较好的建模方法,确定较优模型。  相似文献   

7.
1IntroductionDigitalhologramsareasequenceofcomputergeneratedimageswhichdon’tnedtorecordthelightdistributionoftheobjects,unli...  相似文献   

8.
The COVID-19 pandemic has raised many questions on how to manage an epidemiological and economic crisis around the world. Since the beginning of the COVID-19 pandemic, scientists and policy makers have been asking how effective lockdowns are in preventing and controlling the spread of the virus. In the absence of vaccines, the regulators lacked any plausible alternatives. Nevertheless, after the introduction of vaccinations, to what extent the conclusions of these analyses are still valid should be considered. In this paper, we present a study on the effect of vaccinations within the dynamic stochastic general equilibrium model with an agent-based epidemic component. Thus, we validated the results regarding the need to use lockdowns as an efficient tool for preventing and controlling epidemics that were obtained in November 2020.  相似文献   

9.
The implantation of an artificial intraocular lens (IOL) into a capsular bag in place of an extracted natural, but nontransparent lens is a standard therapy method in the case of cataract. Any decentration or tilt of the IOL can cause a deterioration of the retinal image quality, thus decreasing the vision quality. The analysis of the relative position of Purkinje images being a reflection of the point light source from the refracting surfaces of the eyeball determines the location of IOL inside the eye and thus enables to state its wrong or correct location. The paper describes the Purkinje experimental setup consisting of an illuminator (several infrared LEDs arranged in a circle), an imaging telecentric lens and image recording CCD camera and reports details of the system calibration The usefulness of the experimental setup has been proven both in laboratory conditions using artificial model of the eyeball and in measurements on human subjects. Simulations of the retinal image with different decentrations or tilts are shown.  相似文献   

10.
同时精确测量高温物体温度及发射率的系统   总被引:4,自引:0,他引:4  
利用一种新的方法设计能够同时精确测量高温物体的温度及单色发射率的系统。该系统主要由光学系统、信号放大与处理系统及显示系统三部分组成。介绍了该系统的工作原理与结构,讨论了其中的技术难点及其相应的解决方法,分析了测量波长的选择、扇形板关闭时的L1及开启时的L2的测量精度对单色发射率及温度测量精度的影响  相似文献   

11.
Light propagation in the digital head phantom for virtual near infrared spectroscopy and imaging is calculated by diffusion theory. In theory, diffusion approximation is not valid in a low-scattering cerebrospinal fluid (CSF) layer around the brain. The optical path length and spatial sensitivity profile predicted by the finite element method based upon the diffusion theory are compared with those predicted by the Monte Carlo method to validate a practical implementation of diffusion approximation to light propagation in an adult head. The transport scattering coefficient of the CSF layer is varied from 0.01 to 1.0 mm−1 to evaluate the influence of that layer on the error caused by diffusion approximation. The error is practically ignored and the geometry of the brain surface such as the sulcus structure in the digital head phantom scarcely affects the error when the transport scattering coefficient of the CSF layer is greater than 0.3 mm−1.  相似文献   

12.
STF是KEK为国际直线对撞机(ILC)建立的试验装置. 在STF中, 数字微波低电平系统用于控制超导腔的RF相位和幅度. 在没有实际腔运行的情况下, 设计了一个基于FPGA技术的实时超导腔模拟器, 用于测试微波低电平系统的硬件和算法. 超导腔的数字控制器用FPGA实现, 其中采用了PI反馈控制和前馈控制算法. 测试表明, 超导腔模拟器和控制器都工作良好, 可用于STF微波低电平系统的进一步开发.  相似文献   

13.
苏孝钐  田凌 《应用声学》2012,(6):1473-1475,1488
对于典型的集成电路制造装备,提出了一种面向自动测试系统的多层次测试模型;使用层次化建模方法进行建模,将典型集成电路制造装备的测试模型按层次划分为装备级、子系统级和仪器级;利用XML建立了模块化的测试模型的描述,并使用引用的方式实现测试模型的重用;提出了使用时间信息和GUID确定被引用测试模型可用性的算法;该模型被用于具有工艺腔室的典型集成电路制造装备中,提高了测试模型的重用性,并拓展了对不同层次被测对象的测试能力。  相似文献   

14.

Purpose

The long-term goal of our research is to develop a patient-specific biomechanical model of the supraspinatus muscle and tendon for analyzing the effects of fatty infiltration and pennation angle changes. One input of the model will be the amount and distribution of fat within the muscle. Therefore, the objective of this project was to adapt and validate a novel magnetic resonance imaging pulse sequence for quantifying the extent of fatty infiltration for the supraspinatus muscle.

Methods

Samples of incremental combinations of muscle and fat from a cow were prepared and scanned with our quantitative MR technique. The MR results were compared to actual fat measurements taken using a Soxtec extraction analyzer.

Results

The MR fat quantification results closely match those values determined by Soxtec analysis (R2=.98, root mean square deviation=4.9).

Conclusions

Our MR fat quantification protocol can be used to accurately quantify fatty infiltration in skeletal muscle. This ability to evaluate skeletal muscle tissue noninvasively will improve the efficacy of evaluation of fatty degeneration in assessing tissue quality preoperatively. This can be important in surgical planning of any musculoskeletal repairs, particularly rotator cuff tears.  相似文献   

15.
磁共振成像信号的数字化接收系统设计   总被引:3,自引:3,他引:0  
李睿  肖亮  王为民 《波谱学杂志》2009,26(3):359-368
磁共振成像信号的采集是磁共振成像系统当中最重要的环节之一,设计性能良好的信号接收系统直接关系到成像质量的好坏. 本文根据磁共振信号强度弱、频率高、带宽窄的特性对接收系统进行了统一设计. 详细地对可控增益放大、高速A/D、数字解调以及抽样滤波器等几个部分进行了讨论,给出一整套设计方案,尤其对多级抽样滤波器,根据磁共振成像的性能需求和滤波器的不同特性给出了抽样系数分配和滤波器设计的一般方法. 根据该方案设计出的磁共振信号接收系统有较高的信噪比,已经应用在临床医疗诊断当中.   相似文献   

16.
一种三维数字成像系统的多视点姿态估计方法   总被引:1,自引:1,他引:1  
为校准多视场深度数据,提出基于条纹投影的三维数字成像系统的多视点姿态估计方法。该方法至少在两个视点分别向被测物体投射出一组正交条纹图,利用条纹投影和相位重建技术,将相位图映射为物体的三维空间坐标。进而,利用投影仪的投射过程是摄像机成像过程的逆过程,建立投影仪的投射平面和摄像机的成像平面的对应关系,将“极线几何约束”应用到基于条纹投影的主动三维视觉的姿态估计问题,并在考虑测量数据受噪声影响的条件下,建立了求解视点姿态参量的数学模型。通过优化求解非线性方程可以获得多视点的姿态估计参量。所设计的实验及结果证明了所提出方法的有效性。  相似文献   

17.
孙玉杰  汪岳峰  牛燕雄 《应用光学》2003,24(5):47-48,46
介绍一种应用计算机技术和数字图像处理技术数字化测试分辨率的方法和系统.此测试方法和系统有别于通常的目测方法和装置,避免了目测方法的主观随意性。经证明,适合评测电视跟踪系统的成像性能.  相似文献   

18.
介绍了100MeV射频低电平控制系统的设计及其桌面实验的组成. 通过实测, 验证了他激模式下幅度控制环路和相位控制环路中实现数字式控制的可行性. 初步测试数据及调试过程均表明数字式控制可用于100MeV回旋加速器的射频低电平控制系统.  相似文献   

19.
As the thickness of a disk base is varied, the variation of spherical aberration becomes remarkable. An objective lens system with compensating lenses on the light source side is designed. By moving the compensating lenses along the optical axis backward or forward, the spherical aberration caused by the variation in thickness of the disk base is corrected.  相似文献   

20.
针对校园用电严重浪费问题,为实现校园节能,结合物联网和多种数据传输技术,设计了一种对学校教学楼各教室内电器集中化、网络化和智能化的监控系统。该系统以监控网关为自动控制中心,对ZigBee网络的终端节点采集的每个教室光强、温度、人员活动以及所有教室常用电器开关状态等信息,自动做出智能判断并向ZigBee网络终端下达开关常用电器以及门窗的指令;同时,连接至校园网的监控网关也作为服务器,采用浏览器/服务器和客户端/服务器模式,在Windows客户端、Android手机客户端和Web浏览器实时远程查看每个教室用电器的工作状态,并可以远程人为干预各教室门窗和用电器的开关。该系统不但实现了远程人为控制用电器,而且可根据各教室的光强、温度以及人员活动等情况,自动智能控制每个教室内常用电器及门窗的开关。实际测试表明,该系统具有良好的可靠性和稳定性,大大减少了校园的能源浪费。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号