Le silicium poreux est un matériau qui est actuellement utilisé dans de nombreux domaines, tels que la biologie ou la microélectronique, grâce à ses propriétés remarquables. De nombreuses applications sont étudiées au sein du laboratoire GREMAN, telles que la fabrication de vias électrique ou de capacités 3D. Le matériau étudié au sein de cette thèse est du mésoporeux, qui est utilisé comme substrats dans les applications RF. La caractérisation non destructive de ce matériau est encore limitée, soit selon l’épaisseur de la couche poreuse, soit selon la taille des pores. Cela limite ainsi l’industrialisation des procédés de fabrication de silicium poreux. Une technique ultrasonore de caractérisation est proposée dans cette thèse afin de permettre un suivi de la gravure in situ et en temps réel. Ainsi les variations de gravure peuvent être contrôlées. / Porous silicon is a material that is currently used in many fields such as biology and microelectronics, thanks to its remarkable properties. Non-destructive characterization of this kind of material is still limited, mostly due to thickness of porous layer and pore size. The aim of this work is the development of an ultrasonic characterization method to allow monitoring of in situ etching in real time. First, the study of electrochemical etching and tanks where it is made to have the estimated microgeometric parameters of the porous layer. Through knowledge of the pore size and orientation, the mechanical constants md the values of permeability and tortuosity are estimated. Second, propagation of the ultrasonic waves within the material bi-porous Si-Si layer is examined. Modelling of the porous i layer is performed through the Biot model to estimate the longitudinal speed to calculate the theoretical spectrum transmission through the etched wafer. A measurement using an insertion-substitution method allows a determination of transmission spectrum. The parameters of the porous layer (thickness and porosity ) are determined by an inverse problem resolution, based on a genetic algorithm. A comparison with destructive measurements shows the interest of the ultrasonic measurement.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2009 / Sophisticated measurement methods are currently used extensively to determine the residual stresses in materials. The capabilities of the Hole-Drilling Method, Debro-30 Ultrasonic System and Digital Shearography to determine residual stresses have been explored. The accuracy of these techniques in measuring residual stresses in mild steel specimens is thoroughly examined and discussed. The results obtained from the experiments are consistent with the expected outcomes. Related literature review, experimental procedures, results and their discussion have been outlined. It is hoped that the information provided in this thesis will be of importance to end users, especially engineers and technologists who use these non-destructive methods to evaluate residual stresses in components and materials.

This research focuses on the theoretical analysis, development and experimental evaluation of a water cooled Electromagnetic Acoustic Transducer (EMAT) specifically designed for high-temperature Guided Wave Testing (GWT). Its novel design and detailed calculation of its optimum operating conditions resulted in its effectiveness at high temperatures for both short (500oC) and long-term inspection (250oC). All the steps followed for the theoretical and experimental investigation of the limitations of the existing technology and the development of a probe that can overcome these boundaries are presented. Finite Element Analysis (FEA) was performed for the optimization of the EMAT design and estimation of its ultrasonic and thermal properties at room and high temperatures over time. The wave mode purity profile of the Periodic Permanent Magnet (PPM) EMAT was theoretically studied as well as the effect of temperature rise on its ultrasonic performance. Thermal and Computational Fluid Dynamics (CFD) analysis was accomplished for the EMAT design optimization and calculation of its optimum operating conditions. The experimental validation of the theoretical study was also accomplished. The novel water cooled EMAT was developed and experimentally evaluated regarding its ultrasonic and thermal response at room and high temperatures. An empirical method for the enhancement of EMAT performance and its SNR was established. The wave mode purity characteristics of PPM EMAT were experimentally investigated via Laser vibrometry tests, which agreed with FEA results. The impedance analysis and ultrasonic evaluation of the EMAT at both room and high temperatures against various operating conditions were linked and compared to the results obtained from the ultrasonic, thermal and fluid FEA. In all cases, the experimental study is in good agreement with the theoretical results.

Non-destructive technologies have been applied on predicting the stiffness and strength properties of timber for decades. However, these technologies have rarely been investigated on predicting the properties of thermally modified timber. This study was performed to investigate the non-destructive technologies on estimating of the strength and stiffness properties of thermally modified timber. The material that was utilized for study is full-size structural Norway spruce. Twenty-five thermally modified boards were investigated by applying both non-destructive technologies and static bending test; 25 unmodified boards were used as a control group. Timber grader MTG and Sylvatest Trio are two non-destructive tools that were used for the determining the modulus of elasticity (MOE): MTG is an application of resonance frequency technology and Sylvatest Trio is an application of time-of-flight technology (TOF). The results show that both non-destructive technologies provide good results (??2=0.70 from MTG and??2=0.58 from Sylvatest Trio) on estimating the stiffness properties while poor resultson predicting the strength properties of thermally modified boards.The result shows anoverestimation of modulus of elasticity (MOE) from time-of-flight test compared withthe MOEs gathered from static bending test and resonance frequency test for both thermally modified boards and unmodified ones. The stiffness properties of boards after thermal modification reduced slightly (6.5%) compared with unmodified timbers; while strength properties of thermally modified boards decreased (37.5%) significantlycompared with control group.This study is a part of a bigger study performed at Linneaus University by Joran vanBlokland.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22489号 / 農博第2393号 / 新制||農||1076(附属図書館) / 学位論文||R2||N5269(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 近藤 直, 准教授 小川 雄一, 教授 飯田 訓久 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

This research focuses on the creation, validation, automation, and deployment of a nondestructive vertical electrical impedance (VEI) bridge deck assessment apparatus. A multichannel impedance analyzer with a moving platform is developed that can assess the deterioration state of a bridge deck without stationary traffic control. The multichannel apparatus is capable of taking over 500 impedance samples a second and can scan a bridge deck over 500 times faster than more traditional techniques. This research also shows VEI measurements are inversely proportional to the diffusivity of ions through concrete and that an impedance measurement frequency of 25 kHz is the most predictive measurement frequency of diffusivity. Finally, this research demonstrates the utility of VEI measurements by inspecting five asphalt overlaid bridges. VEI measurements were sensitive to defects in membranes and are one of the only nondestructive measurements that provide useful information about the deterioration state of asphalt overlaid bridge decks.

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No / Fourier transform (FT) Raman spectroscopy was evaluated as a non-destructive analytical tool for assessing the degradative state of archaeological and forensic hair samples. This work follows the successful application of FT-Raman spectroscopy to studies of both modern hair and ancient keratotic biopolymers, such as mummified skin. Fourteen samples of terminal scalp hair from 13 disparate depositional environments were analysed for evidence of structural alteration. Degradative change was evidenced by alteration to the amide I and III modes near 1651 and 1128 cm−1, respectively, and loss of definition to the (CC) skeletal backbone and the impact of environmental contaminants was noted.

Atlikus projekto analizę, buvo pasirinktas optimalus, ekonomiškiausias ir racionaliausias projekto variantas, padėsiantis užtikrinti mažiausias statybos ir eksploatavimo sąnaudas, taip pat ilgiausią tilto eksploatavimo laiką. Ruošiant suvirinimo procedūrų aprašus atlikti ardomieji ir neardomieji bandymai virintinėms jungtims. Bandymai užtikrina, kad virintinės jungties kokybė atitiks standartų keliamus reikalavimams. Neardomieji tyrimo metodai: apžiūrimoji kontrolė, skvarbiųjų dažalų kontrolė, ultragarso kontrolė. Ardomieji tyrimo metodai: tempimas, lenkimas, smūginis tąsumas, kietumas, mikroskopinis ir makroskopinis tyrimai. Darbą sudaro 6 dalys: įvadas, literatūros šaltinių apžvalga, tilto techninio projekto apžvalga, medžiagų skaičiuotiniai stipriai, išvados, literatūros sąrašas. Darbo apimtis – 74 p. teksto be priedų, 43 iliustr., 12 lent., 4 grafikai, 49 bibliografinių šaltinių. / After completing the project analysis, the most optimal, economical and rational project option was chosen, which will secure the lowest construction and manufacturing costs as well as the longest exploitation time. Making welding procedure specification, destructive and non destructive parts were tested for welding joints. The tests showed that the quality of welded joints will be sufficient for the standard requirement. Non destructive research methods: visual testing, penetrant testing, ultrasonic testing, destructive research methods: tensile test, bend test, impact test, hardness test, microscopic and macroscopic tests. The structure of work : introduction, theory research, overview of the bridges' project, calculated strengths of the materials, conclusions, bibliography. Thesis consist of - 74 pages of text, 43 illustrations, 12 tables, 4 graphs, 49 sources.