航空发动机性能图像纹理片段划分方法

为了解决深度学习在航空发动机性能异常检测中出现的数据不平衡的问题,在高频次纹理片段对应性能稳定状态、低频次纹理片段对应异常波动状态的合理假设下,提出了一种航空发动机性能图像纹理片段划分方法。通过研究性能数据空间与RGB彩色空间的映射,提出高维性能数据图像化。引入分形盒维理论,定义纹理特征维数表征性能图像纹理特征,提出基于高频次生长树的图像纹理片段划分方法,实现性能图像按纹理出现频次的精细划分,建立正常样本和异常样本数量接近的数据集。选取多个航段发动机性能数据,与时频图和采样法生成的数据集进行对比验证。验证结果表明:该方法可以生成数量相当且真实客观的正常样本和异常样本,在ResNet50模型上的准确率达91.72%,减小了数据不平衡对准确率的影响。

基于FPGA的高性能CMOS图像采集系统设计

针对高性能CMOS图像传感器数据传输速度快、数据量大的特点,为了满足高性能图像采集系统的设计要求,基于高性能CMOS图像传感器CIS2521芯片,通过研究图像传感器芯片的工作方式及驱动控制特点,设计了一套以FPGA芯片作为控制核心处理器件,搭载CameraLink作为传输接口,以此来实现对高速图像数据的采集、缓存和传输等功能,为此本文给出了详细的硬件设计和实验结果验证。实验结果表明:该系统具有高性能、速度快、体积小、重量轻、速度快、集成度高等优点。

基于图像化变差函数的性能数据异常判别

为提升发动机性能监控的智能化水平,实现性能数据的高效利用,提出了基于图像化变差函数的发动机性能数据异常判别方法。通过研究发动机性能数据的标准化修正方法和图像转化方法,将数值型表示的发动机性能数据转化为发动机性能图像。通过引入变差函数理论,采用4方向的变差函数值表示性能特征值,融合不同时刻不同参数的性能数据。在提取发动机性能图像关键特征点的基础上,定义性能图像间的差异距离,实现基于变差函数的发动机性能图像异常判别方法,从而实现对发动机性能状态的判别。选用若干组实际发动机性能数据对方法进行验证。验证结果表明:该方法运算高效,实现了高维性能数据的降维和对性能图像运行状态的分类,从而判别发动机性能数据的运行状态。

基于质量控制的磁共振成像系统周期性图像性能测试方法

磁共振成像（MRI）系统质量控制的目的是为保证MRI设备图像质量,确保MRI图像的真实可靠,以满足临床诊断对图像质量的需求。依据国家医药行业标准以及医疗诊断对MRI技术的要求,采用周期性图像性能测试方法,对图像信噪比、均匀性、伪影、几何畸变、层厚及空间分辨力等性能参数进行周期性测试;按照数据偏差的严重性将检测周期规定为3~6个月。将测试数据结果进行分析,判断设备各项系统性能是否达到质量评价标准和稳定性质量保证,确保医学影像符合诊断标准,保证影像质量,降低设备的故障率,发现更优的测试方法。通过对MRI影像检查的图像质量进行控制,为临床诊断提供优质的MR图像。

高性能双波段图像融合处理机

报道了自主研制成功的以TMS32 0C6 2 0 1数字信号处理器 (DSP)为核心的高速数字图像融合系统。由于采用了最新高性能DSP及多种硬件、软件方面的优化结构设计 ,因此该系统可以灵活地应用多种融合算法实现可见光———长波红外双通道数字图像的实时或准实时融合处理 ,同时具备手动的像素平移配准功能 。

红外图像多帧检测过程对性能的影响

结合红外图像序列检测算法的具体过程,分析了多帧检测的性能,从概率的角度推导了目标的辐射特性、运动特性、航迹关联算法与多帧检测性能的关系式,并从理论上就这些单个具体的因素对检测性能指标的影响进行了定量的分析计算.

CR/DR图像性能检测方法研究

医用数字摄影(CR/DR)系统的广泛应用,每一个环节都可能对影像质量产生影响,使得其照片或者图像的质量控制显得尤为重要。该文研究CR/DR图像性能相关的技术规范或标准,对检测方法和手段进行讨论,对医学计量检定或医院开展质控工作具有一定的积极作用。

金属离子对喷墨打印纸涂层显色性能的影响

介绍了在涂料中添加不同用量的Cu2+、Fe2+和PDADMAC固色剂对喷墨打印纸涂层的白度、抗水性、吸油墨性(K&N值),打印图像色密度、色差、耐水性、耐光性等性能的影响。研究表明,金属离子对喷墨打印纸打印性能具有改善作用,并得出其最佳的用量。

基于HSI空间伪彩色异构多传感器图像融合仿真

文章从人的视觉系统出发提出一种新的基于HSI空间伪彩色异类多传感器图像融合方法,可以用于解决异构多传感器的图像融合问题,在HSI色彩空间可以大大简化图像分析和处理的工作量。图像融合仿真实验充分验证了该方法可以帮助在人眼和机器识别下克服了由RGB空间伪彩色法造成的融合图像分辨率的下降,同时保留了异类传感器的完整信息,仿真实例证明该算法得到的融合图像的灰度图像其空间分辨率,该算法利于人眼的判读和机器的识别,具有较大的应用价值。

基于尺度不变特征的图像分类技术研究

该文提出基于Bag of words模型,提取图像的SIFT特征,然后用K-medoids算法对其进行聚类,生成词典查询所需用的关键字,最后用adaboosting算法构建分类器,实验采用pascal图像库中的数据进行训练和测试,实验证明,该算法具有训练和测试速度快,分类精度高等特点,特征提取速度和分类速度非常快。

基于Bag of Features模型的害虫图像分类技术研究

将Bag of Features模型结合OpenCV开源图像库提取害虫图像的特征,然后用Kmedoids算法对其进行聚类,生成关键字,最后用AdaBoosting算法构建分类器,实验采用Pascal Voc图像库中的数据进行训练和测试,实验表明,该算法分类精度高、特征提取速度和分类速度也比较快。

Determination of local constitutive behavior and simulation on tensile test of 2219-T87 aluminum alloy GTAW joints

The local and global mechanical responses of gas tungsten arc welds（GTAW） of a 2219-T87 aluminum alloy were investigated with experiment and numerical simulation.Digital image correlation（DIC） was used to access the local strain fields in transversely loaded welds and to determine the local stress-strain curves of various regions in the joint.The results show that the DIC method is efficient to acquire the local stress-strain curves but the curves of harder regions are incomplete because the stress and strain ranges are limited by the weakest region.With appropriate extrapolation,the complete local stress-strain curves were acquired and proved to be effective to predict the tensile behavior of the welded joint.During the tensile process,the fracture initiates from the weld toes owing to their plastic strain concentrations and then propagates along the fusion line,finally propagates into the partially melted zone（PMZ）.

Performance of dual-source CT with high pitch spiral mode for coronary stent patency compared with invasive coronary angiography

Objective To investigate the performance of dual-source computed tomography （DSCT） using high-pitch spiral fliPS） mode for coronary stents patency. Methods We conducted a prospective study on 120 patients with 260 previous stents implanted due to recurred suspicious symptoms of angina scheduled for invasive coronary angiography （ICA）, while DSCT were conducted using HPS mode. Results There was no significant impact of age, body mass index or heat rate （HR） on image quality （P 〉 0.05）, while HR variability had a slight impact on that （P 〈 0.05）. Sensitivity, specificity, positive predictive value （PPV）, negative predictive value （NPV） of DSCT in detection of in-stent restenosis （ISR） based per-patient were 92.3%, 96.7%, 88.9%, and 97.8%, respectively. And those based per-stent were 87%, 96.8%, 83.3%, and 97.7% with un-assessment stents, 97.4%, 99.5%, 97.4%, and 99.5% without un-assessment stents. There was significant differ- ence on sensitivity, specificity, PPV and NPV between diameter 〉 3.0 mm group （93.3%, 97.9%, 87.5%, and 98.9%） and diameter 〈 3.0 mm group （80%, 93.3%, 80.0%, and 93.3%） （P 〈 0.05）, and that between stent number 〉 3 group （82.3%, 77.8%, 66.7%, and 60%） with 〈 3 group （97.3%, 80%, 96.5%, and 75%）. The effective dose of DSCT （1.4 ± 0.5 mSv） is significantly less than that by invasive coronary angiography [4.0 ± 0.8 mSv （P 〈 0.01）]. Conclusion DSCT using HPS mode provides good diagnostic performance on stent patency with lower effective dose in patients with HR 〈 65 beats/rain.

Research on Robotics Application in Fruit Harvesting

The study was aimed to identify the problems and also to suggest some solutions for robotic systems applications in harvesting of kiwi and apples. The results obtained show that physicomechanical properties of the harvested fruits had an effect on the use of robotic systems. Parameters such as weight, height, width, thickness and surface area were identified as the main effect in robotic fruit harvesting. Image processing techniques also had direct effect on robotic systems operation which therefore requires careful selection procedure to achieve results accuracy. It was observed that the C# programming language used in robotic systems fruit harvesting should be parallel with the image processing to ensure accurate conversion of kinematic calculation, system input parameters and constant values. The use of hobby-type parts of a robot in the prototype study showed reliable results. However, to ensure functionality of the robotic systems application, industrial robots and servo engines should be used. It was also observed that the use of a gripper for picking the fruits from the branch must The engines that make the system work should be strong and the be made considering the physicomechanical properties of the fruit. cutting system should also be appropriate.

Novel histogram descriptor for global feature extraction and description

A novel histogram descriptor for global feature extraction and description was presented. Three elementary primitives for a 2×2 pixel grid were defined. The complex primitives were computed by matrix transforms. These primitives and equivalence class were used for an image to compute the feature image that consisted of three elementary primitives. Histogram was used for the transformed image to extract and describe the features. Furthermore, comparisons were made among the novel histogram descriptor, the gray histogram and the edge histogram with regard to feature vector dimension and retrieval performance. The experimental results show that the novel histogram can not only reduce the effect of noise and illumination change, but also compute the feature vector of lower dimension. Furthermore, the system using the novel histogram has better retrieval performance.

美国人体X射线(γ射线)安全设备技术标准研究

随着人体安全检查设备逐渐被公众认识和接受,相关标准的制定及研究也在摸索中逐渐开展。本文主要介绍美国ANSI/IEEE N42.47-2010《人体X射线(γ射线)安检设备图像性能测试标准》的基本内容,并在标准构成、测试体设计、指标限值设定及技术要求等方面进行了讨论。

Numerical simulation of direct shear tests on mechanical properties of talus deposits based on self-adaptive PCNN digital image processing

The macro mechanical properties of materials with characteristics of large scale and complicated structural composition can be analyzed through its reconstructed meso-structures.In this work,the meso-structures of talus deposits that widely exist in the hydro-power engineering in the southwest of China were first reconstructed by small particles according to the in-situ photographs based on the self-adaptive PCNN digital image processing,and then numerical direct shear tests were carried out for studying the mechanical properties of talus deposits.Results indicate that the reconstructed meso-structures of talus deposits are more consistent with the actual situation because the self-adaptive PCNN digital image processing has a higher discrimination in the details of soil-rock segmentation.The existence and random distribution of rock blocks make the initial shear stiffness,the peak strength and the residual strength higher than those of the "pure soil" with particle size less than 1.25 cm apparently,but reduce the displacements required for the talus deposits reaching its peak shear strength.The increase of rock proportion causes a significant improvement in the internal friction angle of talus deposit,which to a certain degree leads to the characteristics of shear stress-displacement curves having a changing trend from the plastic strain softening deformation to the nonlinear strain hardening deformation,while an unconspicuous increase in cohesion.The uncertainty and heterogeneity of rock distributions cause the differences of rock proportion within shear zone,leading to a relatively strong fluctuation in peak strengths during the shear process,while movement features of rock blocks,such as translation,rotation and crossing,expand the scope of shear zone,increase the required shear force,and also directly lead to the misjudgment that the lower shear strength is obtained from the samples with high rock proportion.That,however,just explains the reason why the shear strength gained from a small amount of indoor test data is not consistent with engineering practice.

Peroral cholangioscopy in the new millennium

Peroral cholangioscopy was first described in 1970s and has recently gained popularity.Peroral cholangioscopy is appealing to therapeutic endoscopists because a direct intraluminal view of the biliary duct system offers possibilities for diagnosis and interventions beyond that which other imaging or endoscopic modalities can provide.As the image quality of cholangioscopies improves,so too does their diagnostic capability,and as their durability and maneuverability increases,so too does their potential use for therapeutic applications.This editorial is intended to provide a brief review of recent developments in peroral cholangioscopy and current indications for its use.