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991.
Fuel pin decontamination is the process of removing particulates of radioactive material from its exterior surface. It is an important process step in nuclear fuel fabrication. It assumes more significance with plutonium bearing fuel known to be highly radio-toxic owing to its relatively longer biological half life and shorter radiological half life. Release of even minute quantity of plutonium oxide powder in the atmosphere during its handling can cause alarming air borne activity and may pose a severe health hazard to personnel working in the vicinity. Decontamination of fuel pins post pellet loading operation is thus mandatory before they are removed from the glove box for further processing and assembly. This paper describes the setting up of ultrasonic decontamination process, installed inside a custom built fume-hood in the production line, comprising of a cleaning tank with transducers, heaters, pin handling device and water filtration system and its application in cleaning of fuel pins for prototype fast breeder reactor. The cleaning process yielded a typical decontamination efficiency of more than 99%. 相似文献
992.
The advancement and miniaturization of body implanted medical devices pose several challenges to Ultrasonic Transcutaneous Energy Transfer (UTET), such as the need to reduce the size of the piezoelectric resonator, and the need to maximize the UTET link power-transfer efficiency. Accordingly, the same piezoelectric resonator that is used for energy harvesting at the body implant, may also be used for ultrasonic backward data transfer, for instance, through impedance modulation. 相似文献
993.
In this paper, we present a novel and completely different approach to the problem of scattering material characterization: measuring the degree of predictability of the time series. Measuring predictability can provide information of the signal strength of the deterministic component of the time series in relation to the whole time series acquired. This relationship can provide information about coherent reflections in material grains with respect to the rest of incoherent noises that typically appear in non-destructive testing using ultrasonics. This is a non-parametric technique commonly used in chaos theory that does not require making any kind of assumptions about attenuation profiles. In highly scattering media (low SNR), it has been shown theoretically that the degree of predictability allows material characterization. The experimental results obtained in this work with 32 cement probes of 4 different porosities demonstrate the ability of this technique to do classification. It has also been shown that, in this particular application, the measurement of predictability can be used as an indicator of the percentages of porosity of the test samples with great accuracy. 相似文献
994.
In the present paper, we have theoretically calculated the non linear elastic constants of single crystalline Ni NWs at very broad temperature range 20–300 K validating simple interaction potential model. The temperature dependent ultrasonic attenuation and other related properties are determined using their second and third order elastic constants (SOECs/TOECs). Where possible, the results are compared with experiments from literature. There is a correlation between the thermal conductivity and ultrasonic attenuation in the temperature range 100–300 K. Also, a correlation between the resistivity and ultrasonic attenuation in the temperature range 40–100 K has been established validating the theoretical approach. 相似文献
995.
Sanjeevareddy Kolkoori Christian Hoehne Jens Prager Michael Rethmeier Marc Kreutzbruck 《Ultrasonics》2014
Quantitative evaluation of ultrasonic C-scan images in homogeneous and layered anisotropic austenitic materials is of general importance for understanding the influence of anisotropy on wave fields during ultrasonic non-destructive testing and evaluation of these materials. In this contribution, a three dimensional ray tracing method is presented for evaluating ultrasonic C-scan images quantitatively in general homogeneous and layered anisotropic austenitic materials. The directivity of the ultrasonic ray source in general homogeneous columnar grained anisotropic austenitic steel material (including layback orientation) is obtained in three dimensions based on Lamb’s reciprocity theorem. As a prerequisite for ray tracing model, the problem of ultrasonic ray energy reflection and transmission coefficients at an interface between (a) isotropic base material and anisotropic austenitic weld material (including layback orientation), (b) two adjacent anisotropic weld metals and (c) anisotropic weld metal and isotropic base material is solved in three dimensions. The influence of columnar grain orientation and layback orientation on ultrasonic C-scan image is quantitatively analyzed in the context of ultrasonic testing of homogeneous and layered austenitic steel materials. The presented quantitative results provide valuable information during ultrasonic characterization of homogeneous and layered anisotropic austenitic steel materials. 相似文献
996.
With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. However, work continues to find optimal mode and frequency selection for a given application. This “optimal” mode could give the highest sensitivity to defects or the greatest penetration power, increasing inspection efficiency. Since material properties used for modeling work may be estimates, in many cases guided wave mode and frequency selection can be adjusted for increased inspection efficiency in the field. In this paper, a novel mode and frequency perturbation method is described and used to identify optimal mode points based on quantifiable wave characteristics. The technique uses an ultrasonic phased array comb transducer to sweep in phase velocity and frequency space. It is demonstrated using guided interface waves for bond evaluation. After searching nearby mode points, an optimal mode and frequency can be selected which has the highest sensitivity to a defect, or gives the greatest penetration power. The optimal mode choice for a given application depends on the requirements of the inspection. 相似文献
997.
针对“运动的合成与分解”教学中的难点,制作了3个教具,并提出了相应的演示建议。通过实验演示,引导学生积极思考,突破教学难点。 相似文献
998.
针对中厚板铝制焊接容器的安全评价需要,论文研究了超声导波成像检测技术。通过对铝制焊接容器中不同模态超声导波的频散曲线及波结构分析,选择激励频率为2 MHz的S1模态作为中厚板铝制焊接容器健康监测的导波模态,并研制了适合铝制容器检测的2 MHz/S1模态压电晶片换能器,建立了超声导波成像系统。实验结果表明,该方法仅需经过有限次的扫查,就可以得到容器全壁厚范围内健康信息的超声导波图像,从而清晰地识别容器内的缺陷。该研究为中厚板铝制焊接容器的健康监测提供可行的技术方案。 相似文献
999.
发动机图形绘制与性能计算是火箭设计的关键步骤,通过对固体火箭发动机设计过程的分析,提出CATIA参数化图形绘制技术;以单孔管状装药发动机为例,建立了发动机燃烧室与喷管模型,在VC环境下利用CATIA Automation二次开发技术实现了燃烧室与喷管参数化设计,完成了两者装配与动态显示;利用Matcom实现内弹道压力时间曲线计算,发射段轨道分析;最后完成系统软件编制;实际使用情况表明,使用该软件可快速构造发动机,进行全面的性能分析,为固体火箭发动机方案论证与初步设计提供了有力的工具。 相似文献
1000.