共查询到19条相似文献，搜索用时 421 毫秒
1.
X射线实时成像检测图像最佳放大倍数和最小检出缺陷 总被引：2，自引：1，他引：2
曾祥照 《CT理论与应用研究》2002,11(4):13-16
根据射线检测的基本理论，推导出X射线产时成像检测图像的最佳放大倍数和最小检出缺陷公式，对实时成像检测工艺具有指导作用。 相似文献
2.
通过对钢板试件的数字透射成像检测试验,分析并研究了非晶硅面阵探测器成像检测系统、透照参数、检测工艺与检测图像质量的关系,并给出了检测过程中应该注意的问题.具体试验表明:面阵探测器X射线数字成像系统在一定厚度范围内的像质计灵敏度优于同厚度的射线照相B级要求. 相似文献
3.
目前国内碳纤维复合材料气瓶的定期检验对于内部缺陷还没有成熟的无损检测方法,射线检测可以对内部缺陷进行定性检测,CT检测技术可实现缺陷的精确定位和定量。针对某型号呼吸器用碳纤维复合材料气瓶的结构特点,依据有关定期检验标准,制作各种缺陷,开展CT检测实验研究。结果表明该技术对表面缺陷和纤维层内部缺陷都有很好的检出效果。以厚度2姗的铝内胆为基础,对缺陷的位置和深度进行了估算。 相似文献
4.
数字实时成像(DR)与X射线胶片成像对比分析 总被引：1，自引：0，他引：1
本文简要介绍了数字实时成像技术与X射线胶片成像技术的基本原理,从几个方面对两种技术的特点做了比较分析,并初步讨论了X射线成像技术的发展动向。 相似文献
5.
X-射线检测图像识别的讨论 总被引：1，自引：1，他引：0
曾祥照 《CT理论与应用研究》2004,13(1):29-31
概述了X-射线检测图像识别的影响因素;采取人工识别图像是可行和适宜的;人工、智能化识别图像是发展方向.介绍气瓶对接焊缝X射线实时成像检测. 相似文献
6.
本文关注的是高能双能X射线透视成像以及成像中物体的识别和检测,按照从单能到低能双能再到高能双能的发展脉络介绍了双能X射线DR成像技术背景,详细阐述了高能双能X射线DR成像物质识别原理方法、技术特点和针对性改进,着重讨论了该方法能够用于物质识别的本质,并介绍了该领域面临的挑战和最新进展。 相似文献
7.
本文针对油气管道焊缝射线检测胶片的实际情况,提出一种用于气孔缺陷检测的方法,应用数字图像处理技术对气孔缺陷进行量化分析,并实现计算机辅助评片. 相似文献
8.
为了实现对板状构件的截面重建与缺陷检测,建立了X射线层析截面重建系统。对该系统的成像方法、重建精度、层析截面重建算法等进行研究。首先,提出并论述了采用特殊的成像方式获取X射线透视图像实现分层摄影功能的方法和层析截面重建原理。接着,对上述成像系统进行重建精度分析和运动系统校准。然后,根据上述成像方法获取已知形状检测工件的透视图像,并根据校准结果进行修正,对获取的图像按层析截面重建方法进行重建实验。最后,根据实验重建结果,进行仿真实验并优化重建参数。实验结果表明：探测器旋转步进角为0.5°时,重建图像伪影减小,使用S-L滤波器后,轮廓边缘更为清晰。该层析截面重建方法能有效重建X射线最大入射角内的信息,增大入射角并适当调整检测物角度,可获得清晰的截面图像。 相似文献
9.
X射线三维显微镜及其典型应用 总被引：3，自引：0，他引：3
X射线三维显微镜（显微CT）是目前发展最热门、成长最快的CT成像技术门类之一,在微纳制造技术、新材料以及电子科学等领域起着十分重要的作用并得到广泛的应用。X射线三维显微镜能够以亚微米的细节分辨能力对被检测对象内部结构进行无损的三维成像,是一种新型的检测设备。本文介绍了三英精密仪器有限公司研制的nano Voxel-2000系列X射线三维显微镜的结构和工作原理,展示了该仪器在系统设计、成像方法及应用分析方面的特色。该系列的X射线三维显微镜最大管电压为150 k V,采用5μm的微焦源实现低于500 nm的成像分辨率,能够进行不同尺寸样品、不同分辨率的成像。在此基础上,探讨了X射线显微镜的典型应用,主要对样品的内部结构、形貌进行表征。希望典型应用的实例能起到抛砖引玉的作用,吸引更多学者利用X射线三维显微成像技术开展科学研究,拓宽X射线三维显微镜的应用领域。 相似文献
10.
X射线安全检查技术综述 总被引：15，自引：3，他引：12
近年来,X射线安全检查技术受到航空安全等需要的驱使,得到迅速发展.本文对国内外现有的用X射线探测行李中的爆炸物和其他违禁品的几个主要方法做了一个回顾,阐述了用单能法、双能法、双视角、散射、计算机断层成像法和立体匹配分层成像法进行物质识别的基本原理,并对各种方法的优缺点作了比较和讨论,最后对X射线安全检查技术的未来发展前景进行了展望. 相似文献
11.
长输管道抗震研究的新进展 总被引：2，自引：0，他引：2
本文主要从以下4个方面:地震对长输管道的危害、长输管道震害的研究方法、管道抗震分析和管道抗震的措施,介绍了近几年长输管道抗震方面的研究进展,指出了今后长输管道的研究方向。 相似文献
12.
Sediment detachment and transport processes associated with internal erosion of soil pipes 
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下载免费PDF全文 Subsurface flow can be an important process in gully erosion through its impact on decreasing soil cohesion and erosion resistance as soil water content or pressure increases and more directly by the effects of seepage forces on particle detachment and piping. The development of perched water tables fosters lateral flow that can result in seepage at the surface and/or formation of soil pipes by internal erosion of preferential flow paths. Continued internal erosion of soil pipes can lead to gullies, dam and levee failures. However, the processes involved in particle and aggregate detachment from soil pipe walls and transport processes within soil pipes have not been well studied or documented. This paper reviews the limited research on sediment detachment and transport in macropores and soil pipes and applies the knowledge learned from the much more extensive studies conducted on streams and industrial pipes to hydrogeologic conditions of soil pipes. Knowledge gaps are identified and recommendations are made for future research on sediment detachment and transport in soil pipes. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
13.
富水区隧道合理防排水型式及注浆加固参数研究 总被引：3，自引：0，他引：3
以在建的某近接水库公路隧道为工程依托,建立其渗流场和应力场的双场流固耦合计算模型;选取3种不同的防排水型式为研究对象,对注浆圈厚度、注浆圈渗透系数、控制排水量等因素对隧道内排水量和衬砌外水压力的影响规律进行探究,提出了合理的注浆圈加固参数、控制性排水量以及最优的防排水方式等。研究结果表明：增大注浆圈厚度或降低注浆圈渗透系数均能实现减小衬砌外水压力的目的,但并不意味着注浆圈厚度越厚、渗透系数越低,对隧道涌水量的控制效果就越好,而是存在一个相对经济合理的注浆圈加固参数值;隧道控制排水量以及排水型式对于控制衬砌结构外水压力的大小起到决定性的作用;采用环向排水管及盲管＋墙脚设泄水孔的排水型式,这对衬砌结构受力最为有利。 相似文献
14.
The seismic response analysis of buried pipelines at fault crossings is a complex problem requiring nonlinear 3D soil-structure and large deformation analyses. Such analyses are computationally expensive and the results are hard to evaluate. Therefore, a simple numerical model is needed for engineering and design offices to determine the seismic demand of steel pipes at fault crossings. This paper presents a simplified numerical model for buried steel pipes crossing strike-slip faults and oriented perpendicular to the fault. Two pipes with different diameter to thickness (D/t) ratios and steel grades are used in the study. The proposed model permits plastic hinge formations in the pipe due to incrementally applied fault movements, allows determination of the critical length of the pipeline and measure strains developed on the tension and compression sides in the pipe. The model also considers the effect of bending as well as axial strains due to stretching. 相似文献
15.
埋地双排复合式管体结构在SH波作用下的动力分析 总被引：1，自引：0，他引：1
以波动理论为基础,采用复变函数法,给出了地下双排复合式管体结构在SH波作用下的解析解。分析了入射波角度、频率变化,管体埋深、内管的厚度变化等参数对管体动应力集中的影响。结果表明:复合式管体内侧的动应力集中峰值明显高于外侧;高频入射时,双排管体在给定距离之间的相互影响较大,动应力集中峰值向邻侧偏移;复合式管体内管越薄,动应力集中峰值越大;垂直入射时,动应力集中峰值受埋深的影响呈周期性变化。 相似文献
16.
Subsurface conducting pipes can be either a target or a noise source in geophysical surveying. Their effect as a noise source in resistivity imaging can be so severe as to render the geophysical data uninterpretable. A method is developed here for identifying, locating and removing the effects of subsurface conducting pipes from image data, thus revealing the background resistivity structure.
A previously known analytic solution for the potential distribution produced by current injection in a uniform half‐space containing an infinitely long conducting cylinder is used to calculate apparent resistivities corresponding to electrode arrays on the surface of the half‐space. Most results concern the Wenner array and an examination is made of the effects produced by varying the electrode spacing and the depth, size and orientation of the pipe with respect to the array. A method is developed for locating pipes in resistivity image data by cross‐correlation of the analytic solution with the measured field data. Pipe effects are then removed by multiplying each datum point in the measurements by the reciprocal of the corresponding value in the analytic solution. The success of the method is demonstrated by applications to synthetic data sets involving one or two pipes embedded in non‐uniform half‐spaces.
In further examples, the method is applied to some measured resistivity images from an ex‐industrial site (a former oil distribution terminal), where an electromagnetic survey had previously revealed a labyrinth of underground pipes. The method is shown to be successful in removing the effects of the pipes to reveal the underlying geology. 相似文献
A previously known analytic solution for the potential distribution produced by current injection in a uniform half‐space containing an infinitely long conducting cylinder is used to calculate apparent resistivities corresponding to electrode arrays on the surface of the half‐space. Most results concern the Wenner array and an examination is made of the effects produced by varying the electrode spacing and the depth, size and orientation of the pipe with respect to the array. A method is developed for locating pipes in resistivity image data by cross‐correlation of the analytic solution with the measured field data. Pipe effects are then removed by multiplying each datum point in the measurements by the reciprocal of the corresponding value in the analytic solution. The success of the method is demonstrated by applications to synthetic data sets involving one or two pipes embedded in non‐uniform half‐spaces.
In further examples, the method is applied to some measured resistivity images from an ex‐industrial site (a former oil distribution terminal), where an electromagnetic survey had previously revealed a labyrinth of underground pipes. The method is shown to be successful in removing the effects of the pipes to reveal the underlying geology. 相似文献
17.
基于土体的等效粘弹性模型,结合场地典型剖面的土体特性以及室内实验确定的各力学参数,采用时域积分和迭代的方法研究了沁河倒虹吸管道在地震作用下的反应,分析了管道截面中间底部点绝对地震位移、顶部点相对于底部点的地震动位移及管道动静综合主应力的变化规律;并根据有限元时程法的分析结果,按照混凝土承载能力极限状态设计式,对管身混凝土的抗拉、抗压安全度进行校核。结果表明,在人工地震波、调整后的E1 Centro和Pulgas地震波分别输入的情况下沁河渠道倒虹吸管道均满足抗震要求。 相似文献
18.
R. P. Smart J. Holden K. J. Dinsmore A. J. Baird M. F. Billett P. J. Chapman R. Grayson 《水文研究》2013,27(11):1523-1534
Natural soil pipes are found in peatlands, but little is known about their hydrological role. This paper presents the most complete set of pipe discharge data to date from a deep blanket peatland in Northern England. In a 17.4‐ha catchment, we identified 24 perennially flowing and 60 ephemerally flowing pipe outlets. Eight pipe outlets along with the catchment outlet were continuously gauged over an 18‐month period. The pipes in the catchment were estimated to produce around 13.7% of annual streamflow, with individual pipes often producing large peak flows (maximum peak of 3.8 l s?1). Almost all pipes, whether ephemerally or perennially flowing, shallow or deep (outlets > 1 m below the peat surface), showed increased discharge within a mean of 3 h after rainfall commencement and were dominated by stormflow, indicating good connectivity between the peatland surface and the pipes. However, almost all pipes had a longer period between the hydrograph peak and the return to base flow compared with the stream (mean of 23.9 h for pipes, 19.7 h for stream). As a result, the proportion of streamflow produced by the pipes at any given time increased at low flows and formed the most important component of stream discharge for the lowest 10% of flows. Thus, a small number of perennially flowing pipes became more important to the stream system under low‐flow conditions and probably received water via matrix flow during periods between storms. Given the importance of pipes to streamflow in blanket peatlands, further research is required into their wider role in influencing stream water chemistry, water temperature and fluvial carbon fluxes, as well as their role in altering local hydrochemical cycling within the peat mass itself. Enhanced piping within peatlands caused by environmental change may lead to changes in the streamflow regime with larger low flows and more prolonged drainage of the peat. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
19.
Centrifuge modeling of PGD response of buried pipe 总被引：1，自引：1，他引：0
MichaelO＇Rourke VikramGadicherla TarekAbdoun 《地震工程与工程振动(英文版)》2005,4(1):69-73
A new centrifuge based method for determining the response of continuous buried pipe to PGD is presented. The physical characteristics of the RPI‘s 100 g-ton geotechnical centrifuge and the current lifeline experiment split-box are described: The split-box contains the model pipeline and surrounding soil and is manufactured such that half can be offset, in flight, simulating PGD. In addition, governing similitude relations which allow one to determine the physical characteristics, (diameter, wall thickness and material modulus of elasticity) of the model pipeline are presented. Finally, recorded strains induced in two buried pipes with prototype diameters of 0.63 m and 0.95 m (24 and 36 inch) subject to 0.6 and 2.0 meters (2 and 6 feet) of full scale fault offsets and presented and compared to corresponding FE results. 相似文献