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Статті в журналах з теми "Thermal NDT methods"
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Marinetti, S., L. Finesso, and E. Marsilio. "Matrix factorization methods: Application to thermal NDT/E." NDT & E International 39, no. 8 (December 2006): 611–16. http://dx.doi.org/10.1016/j.ndteint.2006.04.008.
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Dattoma, Vito, Francesco Panella, Alessandra Pirinu, and Andrea Saponaro. "Advanced NDT Methods and Data Processing on Industrial CFRP Components." Applied Sciences 9, no. 3 (January 24, 2019): 393. http://dx.doi.org/10.3390/app9030393.
Повний текст джерелаАнотація:
In this work, enhanced thermal data processing is developed with experimental procedures, improving visualization algorithm for sub-surface defect detection on industrial composites. These materials are prone to successful infrared nondestructive investigation analyses, since defects are easily characterized by temperature response under thermal pulses with reliable results. Better defect characterization is achieved analyzing data with refined processing and experimental procedures, providing detailed contrasts maps where defects are better distinguished. Thermal data are analyzed for different CFRP specimens with artificial defects and experimental procedures are verified on real structural aeronautical component with internal anomalies due to impact simulation. A better computation method is found to be useful for simultaneous defect detection by means of automatic mapping of absolute contrast, optimized to identify defect boundaries.
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Nowacki, J., and N. Sieczkiewicz. "Prospective NDT methods for assessing the quality of polymer composites under production conditions." Archives of Materials Science and Engineering 2, no. 87 (October 1, 2017): 66–74. http://dx.doi.org/10.5604/01.3001.0010.7447.
Повний текст джерелаАнотація:
Purpose: Analysis of non-destructive testing systems polymer composite in terms of current solutions in the area of methodology and devices. Analysis of contemporary standards for non-destructive testing of polymer composites established by ASTM. Analysis of Flir ONE camera capabilities in non-destructive testing composite carbon-epoxy composites. Design/methodology/approach: The thermal imaging tests of the carbon-epoxy composite discontinuity were carried out using a thermal imaging camera and Flir One accessory for an iOS phone. The tests were performed on carbon-epoxy composite samples measuring 100x100 mm. In order to simulate the discontinuity in a sample by the Resin Transfer Molding (RTM) method, a 30x30 mm PTFE film was inserted between the reinforcement layers. The thickness of the sample with discontinuity was 2 mm. Water was added to the selected sample sites. Samples were placed on a 50°C heated plate to record thermal images and thermal images combined with visual contours of samples with simulated defects. Area Calculator – SketchAndCalc Icalc, Inc. was used to describe the size and location of the defects. Findings: As a result of the tests, the use of the Flir One thermal imaging device in epoxycarbon composite discontinuity tests has been demonstrated, and a methodology has been proposed to measure geometrical features of defects. Research limitations/implications: The description of welded joint structure and mechanical properties was based on welding toughened steels by using an innovative welding method and a filler that has been proposed. Practical implications: The development of thermal imaging studies of polymer composite discontinuity using the Flir One thermal imaging camera and accessory with iOS opens up the possibility of conducting a basic inspection of composite materials in production plants, and even for simplicity – also in small laboratories. Originality/value: In order to improve the quality of imaging of small items using the Flir One mobile camera, the use of cheap and readily available lenses used in laser optics has been tested positively.
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Plšková, Iveta, Michal Matysík, and Zdeněk Chobola. "Monitoring of Thermal Damage Evolution in Concrete Parts by Acoustic NDT Methods." Key Engineering Materials 808 (June 2019): 159–64. http://dx.doi.org/10.4028/www.scientific.net/kem.808.159.
Повний текст джерелаАнотація:
The paper presents the results of the experimental work which was focused on the use of the Impact-echo method for testing of concrete specimens damaged by high-temperature. The test specimens were heated to 600 and 800 °C for sixty, one hundred twenty and three hundred minutes. After heating, the samples were continuously cooled to room temperature and tested by Impact-echo method.
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Land, Patrick, Petros Stavroulakis, Richard Crossley, Patrick Bointon, Harvey Brookes, Jon Wright, Svetan Ratchev, and David Branson. "Evaluation of Thermal Roll Formed Thick Composite Panels Using Surface NDT Methods." SAE International Journal of Materials and Manufacturing 11, no. 1 (September 19, 2017): 37–42. http://dx.doi.org/10.4271/05-11-01-0005.
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Kostyleva, Liliya Yu, Oleg V. Loginovskiy, Evgeniya A. Retc, and Igor M. Yachikov. "Possibilities of using mathematical models for thermal nondestructive testing of defects in multilayer bimetallic plates." Bulletin of the South Ural State University. Ser. Computer Technologies, Automatic Control & Radioelectronics 22, no. 1 (January 2022): 53–64. http://dx.doi.org/10.14529/ctcr220104.
Повний текст джерелаАнотація:
There is an actual task of delamination detection in multilayer bimetallic materials. Various methods of nondestructive testing (NDT) are used to solve it, including the method of transient thermal NDT. This method consists in remote registration, visualization and analysis of thermal (temperature) fields, which depend on thermophysical and geometric characteristics, thermal effect capacity and internal structure features of the object. The internal structure defects cause the appearance of abnormal temperature zones on the object surface. Their analysis allows us to judge the presence of changes in the material as a whole or in individual areas. It is possible to understand whether there is a defect under the anomalous site, and what its parameters are, if there is an adequate mathematical model that theoretically describes the dependence of the measuring results on the properties of the object and the selected technological modes. This model is a significant component of thermal NDT systems. For the same object or process, a certain set of mathematical models can be compiled, differing in the number of factors taken into account, the assumptions made, the completeness and accuracy of the description of the state of the object or the conditions of the process. The set of factors is determined by the purpose of the study, and in order to unambiguously determine the model of the thermal state, it is necessary to describe the characteristics of the object (geometric shape and thermophysical characteristics of the material) and the heat exchange process (characteristics of heat sources, initial and boundary conditions). Aim. To analyze the existing mathematical models for the research object – a multilayer bimetallic plate with delaminations between the outer and inner layers, and to identify common approaches to modeling the processes of thermal NDT of multilayer objects. Materials and methods. The structure of the mathematical model of the thermal state of the object is determined. An analytical review of mathematical models of thermal NDT of multilayer objects is performed. Results. The requirements, assumptions and limitations for a mathematical model of thermal NDT of a multilayer bimetallic plate with delamination defects are formulated. Conclusion. On the basis of the considered approaches to the mathematical modeling of the thermal state of multilayer objects with ideal layers contact and delamination defects, the necessary factors for the development of a model for the transient thermal NDT processes of the studied objects are determined.
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Qu, Zhi, Peng Jiang, and Weixu Zhang. "Development and Application of Infrared Thermography Non-Destructive Testing Techniques." Sensors 20, no. 14 (July 10, 2020): 3851. http://dx.doi.org/10.3390/s20143851.
Повний текст джерелаАнотація:
Effective testing of defects in various materials is an important guarantee to ensure its safety performance. Compared with traditional non-destructive testing (NDT) methods, infrared thermography is a new NDT technique which has developed rapidly in recent years. Its core technologies include thermal excitation and infrared image processing. In this paper, several main infrared thermography nondestructive testing techniques are reviewed. Through the analysis and comparison of the detection principle, technical characteristics and data processing methods of these testing methods, the development of the infrared thermography nondestructive testing technique is presented. Moreover, the application and development trend are summarized.
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Schmid, Maximilian, Sri Krishna Bhogaraju, E. Liu, and Gordon Elger. "Comparison of Nondestructive Testing Methods for Solder, Sinter, and Adhesive Interconnects in Power and Opto-Electronics." Applied Sciences 10, no. 23 (November 28, 2020): 8516. http://dx.doi.org/10.3390/app10238516.
Повний текст джерелаАнотація:
Reliability is one of the major requirements for power and opto-electronic devices across all segments. High operation temperature and/or high thermomechanical stress cause defects and degradation of materials and interconnects, which may lead to malfunctions with costly or even life-threatening consequences. To avoid or at least reduce failures, nondestructive testing (NDT) methods are common within development and production of power and opto-electronics. Currently, the dominating NDT methods are X-ray, scanning acoustic microscopy (SAM), and transient thermal analysis (TTA). However, they have different strengths and weaknesses with respect to materials and mechanical designs. This paper compares these NDT methods for different interconnect technologies, i.e., reflow soldering, adhesive, and sintered interconnection. While X-ray provided adequate results for soldered interfaces, inspection of adhesives and sintered interconnects was not possible. With SAM, evaluation of adhesives and sintered interconnects was also feasible, but quality depended strongly on the sample under test. TTA enabled sufficiently detailed results for all the interconnect applications. Automated TTA equipment, as the in-house developed tester used within this investigation, enabled measurement times compatible with SAM and X-ray. In the investigations, all methods revealed their pros and cons, and their selection has to depend on the sample under tests and the required analysis depth and data details. In the paper, guidelines are formulated for an appropriate decision on the NDT method depending on sample and requirements.
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Ba, Abdoulaye, Huu Kien Bui, Gérard Berthiau, Didier Trichet, and Guillaume Wasselynck. "Simulation of induction thermography NDT technique using SIBC." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 39, no. 5 (July 3, 2020): 1071–83. http://dx.doi.org/10.1108/compel-01-2020-0007.
Повний текст джерелаАнотація:
Purpose This paper aims to present a lightened 3D finite element model (FEM) for coupled electromagnetic thermal simulation of the induction thermography non-destructive testing (NDT) technique to reduce the computation time. Design/methodology/approach The time harmonic electromagnetic problem is expressed in A – ϕ formulation and lightened by using the surface impedance boundary condition (SIBC) applied to both the massive induction coil surface and the surface of conductor workpiece including open cracks. The external circuit is taken into account by using the impressed voltage or the impressed current formulation. The thermal diffusion in the workpiece is solved by using surface electromagnetic power density as thermal source. Findings The accuracy and the usefulness of the method for the design of the induction thermography NDT technique have been shown with acceptable deviation compared with a full FEM model. It is also observed that at high frequency, when the ratio between the local radius of the conductor and the skin depth is high, a very good accuracy can be obtained with the SIBC methods. At lower frequency, the effect of the curvature of the surface becomes significant. In this case, the use of the Mitzner’s impedance can help to correct the error. Originality/value The SIBC can be used for both massive coil and workpieces with open cracks to alleviate 3D FEMs of the coupled electrothermal model. The implementation in matrix form of the coupled electrothermal formulation is given in details. The comparisons with reference analytical solution and full 3D FEM show the accuracy and performance of the method. In the test case presented, the computation time is 6.6 times lower than the classical model.
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Balasubramaniam, Kaleeswaran, Dominika Ziaja, Michał Jurek, Piotr Fiborek, and Paweł Malinowski. "Experimental and Numerical Analysis of Multiple Low-Velocity Impact Damages in a Glass Fibered Composite Structure." Materials 14, no. 23 (November 28, 2021): 7268. http://dx.doi.org/10.3390/ma14237268.
Повний текст джерелаАнотація:
Glass fiber-reinforced polymer structures (GFRPS) are widely used in civil and mechanical fields due to their light weight and corrosion resistance. However, these structures are prone to damage with very-low-energy impacts. The reliability of such structures is of prime importance before their installation and usage. This study aimed to identify, visualize, localize, and verify multiple barely visible impact damage (BVID) in a GFRPS using a combination of guided waves (GW)-based online structural health monitoring (SHM) and thermal strain-based nondestructive testing (NDT) approaches. Global NDT techniques like the use of a laser Doppler vibrometer (LDV) and digital image correlation (DIC) were used in the experimental analysis. The effectiveness of the experimental LDV-GW process was also checked numerically with the spectral element method (SEM). A threshold-based baseline free SHM approach to effectively localize the damages was proposed along with quick DIC verification of composite structure with thermal loading based on short-pulse heating as an excitation source. This study analyzed combined experimental- and numerical-based SHM-NDT methods in characterizing the multiple BVIDs located in a GFRPS.
Дисертації з теми "Thermal NDT methods"
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Славков, Віктор Миколайович. "Розробка цифрового фотографічного методу теплового контролю металів при високих температурах". Thesis, НТУ "ХПІ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/17036.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.13 - прилади і методи контролю та визначення складу речовин. Національний технічний університет "Харківський політехнічний інститут", Харків, 2015 р.
Дисертацію присвячено розробці методу теплового контролю металів при температурах понад 600 °С із використанням, у якості детектора теплового випромінювання, цифрового фотоапарата. На основі встановлених теоретичних положень методу розроблені програмні алгоритми обробки цифрових зображень, що дозволили: провести процедуру калібрування цифрового фотоапарата у діапазоні яскравісних температур 500…1800 °С та встановити калібрувальні залежності у вигляді математичних рівнянь; здійснити тепловий контроль металевих пластин, об'ємних металевих зразків та встановити присутні в них дефекти; вирішити додаткові задачі теплового контролю металів, а саме встановити значення питомої масової теплоємності металу; моделювати рівномірні температурні поля на поверхні металевих пластин; встановити розподілення коефіцієнта теплового випромінювання поверхні металевих пластин.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.11.13 - devices and methods of testing and materials composition determination. - National Technical University "Kharkiv Politechnical Institute", Kharkiv, 2015. The dissertation is devoted to development of a thermal control metals method at temperatures above 600 °C using as thermal radiation detector, digital camera. On the basis of the established method of theoretical positions were developed software algorithms for digital image processing that allowed: to carry a digital camera calibration brightness temperature in the range of 500...1800 °C and set the calibration curve in the form of mathematical equations; perform thermal control of metal plates, bulk metallic samples and established the presence of defects; to solve additional tasks of thermal metals control, namely to establish the value of the specific heat capacity of the metal mass; simulate uniform temperature field on the surface of the metal plates; determine the distribution coefficient of thermal radiation from the metal plates surface.
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Славков, Віктор Миколайович. "Розробка цифрового фотографічного методу теплового контролю металів при високих температурах". Thesis, НТУ "ХПІ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/17002.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.13 - прилади і методи контролю та визначення складу речовин. Національний технічний університет "Харківський політехнічний інститут", Харків, 2015 р.
Дисертацію присвячено розробці методу теплового контролю металів при температурах понад 600 °С із використанням, у якості детектора теплового випромінювання, цифрового фотоапарата. На основі встановлених теоретичних положень методу розроблені програмні алгоритми обробки цифрових зображень, що дозволили: провести процедуру калібрування цифрового фотоапарата у діапазоні яскравісних температур 500…1800 °С та встановити калібрувальні залежності у вигляді математичних рівнянь; здійснити тепловий контроль металевих пластин, об'ємних металевих зразків та встановити присутні в них дефекти; вирішити додаткові задачі теплового контролю металів, а саме встановити значення питомої масової теплоємності металу; моделювати рівномірні температурні поля на поверхні металевих пластин; встановити розподілення коефіцієнта теплового випромінювання поверхні металевих пластин.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.11.13 - devices and methods of testing and materials composition determination. - National Technical University "Kharkiv Politechnical Institute", Kharkiv, 2015. The dissertation is devoted to development of a thermal control metals method at temperatures above 600 °C using as thermal radiation detector, digital camera. On the basis of the established method of theoretical positions were developed software algorithms for digital image processing that allowed: to carry a digital camera calibration brightness temperature in the range of 500...1800 °C and set the calibration curve in the form of mathematical equations; perform thermal control of metal plates, bulk metallic samples and established the presence of defects; to solve additional tasks of thermal metals control, namely to establish the value of the specific heat capacity of the metal mass; simulate uniform temperature field on the surface of the metal plates; determine the distribution coefficient of thermal radiation from the metal plates surface.
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Luz, Andre Miguel Godinho da. "Predictive modelling and multiscale NDE methods in failure assessment of thermal barrier coatings." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9065.
Повний текст джерелаАнотація:
The use of thermal barrier coatings (TBCs) allows advanced gas turbine engines to operate at a temperature higher than the incipient melt temperature of the superalloy from which the engine components are made, thereby enhancing the performance and efficiency of the engine. However, delamination cracks initiated in these coatings during service limit their applications. This investigation analysed the effects of thermal cycling on the structure, thermo-mechanical properties and lifetime of Ni-based superalloy samples coated with a TBC. The results indicate that the coating system exhibits substantial changes during its life, with the thermo-mechanical properties of the TBC layers being highly sensitive to temperature and cyclic oxidation. The current study also presents a new finite element model that describes the evolution of the stress state within a thermal barrier coating subjected to thermal cycling loading. This computational framework was used to identify the optimal design parameters through a newly proposed sensitivity index, so that TBCs can be engineered with improved lifetime. Photoluminescence piezo-spectroscopy has been used to identify non-destructively the onset of microcracks and monitor their propagation through a proposed local damage factor that combines spectral shape evolution with peak shift. The computational spectral simulation was based on coupling the finite element model for the calculation of stress with an external routine for the prediction of luminescence spectra. A new non-destructive multi-sensor diagnostics procedure based on the combination of imaging- and laser-based techniques was presented. It has been demonstrated that it can accurately determine the remaining life of high-temperature coatings, and therefore it represents an important development direction for improving the reliability of TBCs. It is concluded that the results obtained in this research were quite satisfactory, which suggests that further model development and field testing of the non-destructive methodology are warranted for predictive failure assessment of thermal barrier coating systems. Keywords Thermal barrier coating Material properties Finite element modeling Photoluminescence piezo-spectroscopy Non-destructive evaluation
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MINDA, ELISE. "SENSITIVITY STUDIES ON NONDESTRUCTIVE EVALUATION (NDE) METHODS FOR MONITORING FATIGUE AND THERMAL EMBRITTLEMENT IN AUSTENITIC AND FERRITIC STEEL NUCLEAR REACTOR PLANT (NRP) COMPONENTS." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1195611890.
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Eiras, Fernández Jesús Nuño. "Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/71439.
Повний текст джерелаАнотація:
[EN] The test for determining the resonance frequencies has traditionally been used to investigate the mechanical integrity of concrete cores, to assess the conformity of concrete constituents in different accelerated durability tests, and to ascertain constitutive properties such as the elastic modulus and the damping factor. This nondestructive technique has been quite appealed for evaluation of mechanical properties in all kinds of durability tests. The damage evolution is commonly assessed from the reduction of dynamic modulus which is produced as a result of any cracking process. However, the mechanical behavior of concrete is intrinsically nonlinear and hysteretic. As a result of a hysteretic stress-strain behavior, the elastic modulus is a function of the strain. In dynamic tests, the nonlinearity of the material is manifested by a decrease of the resonance frequencies, which is inversely proportional to the excitation amplitude. This phenomenon is commonly referred as fast dynamic effect. Once the dynamic excitation ceases, the material undergoes a relaxation process whereby the elastic modulus is restored to that at rest. This phenomenon is termed as slow dynamics. These phenomena (fast and slow dynamics) find their origin in the internal friction of the material. Therefore, in cement-based materials, the presence of microcracks and interfaces between its constituents plays an important role in the material nonlinearity. In the context of the assessment of concrete durability, the damage evolution is based on the increase of hysteresis, as a result of any cracking process. In this thesis three different nondestructive techniques are investigated, which use impacts for exciting the resonant frequencies. The first technique consists in determining the resonance frequencies over a range of impact forces. The technique is termed Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). It consists in ascertaining the downward resonant frequency shift that the material undergoes upon increasing excitation amplitude. The second technique consists in investigating the nonlinear behavior by analyzing the signal corresponding to a single impact. This is, to determine the instantaneous frequency, amplitude and attenuation variations corresponding to a single impact event. This technique is termed as Nonlinear Resonant Acoustic Single Impact Spectroscopy (NSIRAS). Two techniques are proposed to extract the nonlinear behavior by analyzing the instantaneous frequency variations and attenuation over the signal ring down. The first technique consists in discretizing the frequency variation with time through a Short-Time Fourier Transform (STFT) based analysis. The second technique consists of a least-squares fit of the vibration signals to a model that considers the frequency and attenuation variations over time. The third technique used in this thesis can be used for on-site evaluation of structures. The technique is based on the Dynamic Acousto- Elastic Test (DAET). The variations of elastic modulus as derived through NIRAS and NSIRAS techniques provide an average behavior and do not allow derivation of the elastic modulus variations over one vibration cycle. Currently, DAET technique is the only one capable to investigate the entire range of nonlinear phenomena in the material. Moreover, unlike other DAET approaches, this study uses a continuous wave source as probe. The use of a continuous wave allows investigation of the relative variations of the elastic modulus, as produced by an impact. Moreover, the experimental configuration allows one-sided inspection.[ES] El ensayo de determinación de las frecuencias de resonancia ha sido tradicionalmente empleado para determinar la integridad mecánica de testigos de hormigón, en la evaluación de la conformidad de mezclas de hormigón en diversos ensayos de durabilidad, y en la terminación de propiedades constitutivas como son el módulo elástico y el factor de amortiguamiento. Esta técnica no destructiva ha sido ampliamente apelada para la evaluación de las propiedades mecánicas en todo tipo de ensayos de durabilidad. La evolución del daño es comúnmente evaluada a partir de la reducción del módulo dinámico, producido como resultado de cualquier proceso de fisuración. Sin embargo, el comportamiento mecánico del hormigón es intrínsecamente no lineal y presenta histéresis. Como resultado de un comportamiento tensión-deformación con histéresis, el módulo elástico depende de la deformación. En ensayos dinámicos, la no linealidad del material se manifiesta por una disminución de las frecuencias de resonancia, la cual es inversamente proporcional a la amplitud de excitación. Este fenómeno es normalmente denominado como dinámica rápida. Una vez la excitación cesa, el material experimenta un proceso de relajación por el cual, el módulo elástico es restaurado a aquel en situación de reposo. Este fenómeno es denominado como dinámica lenta. Estos fenómenos ¿dinámicas rápida y lenta¿ encuentran su origen en la fricción interna del material. Por tanto, en materiales basados en cemento, la presencia de microfisuras y las interfaces entre sus constituyentes juegan un rol importante en la no linealidad mecánica del material. En el contexto de evaluación de la durabilidad del hormigón, la evolución del daño está basada en el incremento de histéresis, como resultado de cualquier proceso de fisuración. En esta tesis se investigan tres técnicas diferentes las cuales utilizan el impacto como medio de excitación de las frecuencias de resonancia. La primera técnica consiste en determinar las frecuencias de resonancia a diferentes energías de impacto. La técnica es denominada en inglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Ésta consiste en relacionar el detrimento que el material experimenta en sus frecuencias de resonancia, con el aumento de la amplitud de la excitación. La segunda técnica consiste en investigar el comportamiento no lineal mediante el análisis de la señal correspondiente a un solo impacto. Ésta consiste en determinar las propiedades instantáneas de frecuencia, atenuación y amplitud. Esta técnica se denomina, en inglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Se proponen dos técnicas de extracción del comportamiento no lineal mediante el análisis de las variaciones instantáneas de frecuencia y atenuación. La primera técnica consiste en la discretización de la variación de la frecuencia con el tiempo, mediante un análisis basado en Short-Time Fourier Transform (STFT). La segunda técnica consiste en un ajuste por mínimos cuadrados de las señales de vibración a un modelo que considera las variaciones de frecuencia y atenuación con el tiempo. La tercera técnica empleada en esta tesis puede ser empleada para la evaluación de estructuras in situ. La técnica se trata de un ensayo acusto-elástico en régimen dinámico. En inglés Dynamic Acousto-Elastic Test (DAET). Las variaciones del módulo elástico obtenidas mediante los métodos NIRAS y NSIRAS proporcionan un comportamiento promedio y no permiten derivar las variaciones del módulo elástico en un solo ciclo de vibración. Actualmente, la técnica DAET es la única que permite investigar todo el rango de fenómenos no lineales en el material. Por otra parte, a diferencia de otras técnicas DAET, en este estudio se emplea como contraste una onda continua. El uso de una onda continua permite investigar las variaciones relativas del módulo elástico, para una señal transito
[CAT] L'assaig de determinació de les freqüències de ressonància ha sigut tradicionalment empleat per a determinar la integritat mecànica de testimonis de formigó, en l'avaluació de la conformitat de mescles de formigó en diversos assajos de durabilitat, i en la terminació de propietats constitutives com són el mòdul elàstic i el factor d'amortiment. Esta tècnica no destructiva ha sigut àmpliament apel·lada per a l'avaluació de les propietats mecàniques en tot tipus d'assajos de durabilitat. L'evolució del dany és comunament avaluada a partir de la reducció del mòdul dinàmic, produït com resultat de qualsevol procés de fisuración. No obstant això, el comportament mecànic del formigó és intrínsecament no lineal i presenta histèresi. Com resultat d'un comportament tensió-deformació amb histèresi, el mòdul elàstic depén de la deformació. En assajos dinàmics, la no linealitat del material es manifesta per una disminució de les freqüències de ressonància, la qual és inversament proporcional a l'amplitud d'excitació. Este fenomen és normalment denominat com a dinàmica ràpida. Una vegada l'excitació cessa, el material experimenta un procés de relaxació pel qual, el mòdul elàstic és restaurat a aquell en situació de repòs. Este fenomen és denominat com a dinàmica lenta. Estos fenòmens --dinámicas ràpida i lenta troben el seu origen en la fricció interna del material. Per tant, en materials basats en ciment, la presència de microfissures i les interfícies entre els seus constituents juguen un rol important en la no linealitat mecànica del material. En el context d'avaluació de la durabilitat del formigó, l'evolució del dany està basada en l'increment d'histèresi, com resultat de qualsevol procés de fisuración. En esta tesi s'investiguen tres tècniques diferents les quals utilitzen l'impacte com a mitjà d'excitació de les freqüències de ressonància. La primera tècnica consistix a determinar les freqüències de ressonància a diferents energies d'impacte. La tècnica és denominada en anglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Esta consistix a relacionar el detriment que el material experimenta en les seues freqüències de ressonància, amb l'augment de l'amplitud de l'excitació. La segona tècnica consistix a investigar el comportament no lineal per mitjà de l'anàlisi del senyal corresponent a un sol impacte. Esta consistix a determinar les propietats instantànies de freqüència, atenuació i amplitud. Esta tècnica es denomina, en anglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Es proposen dos tècniques d'extracció del comportament no lineal per mitjà de l'anàlisi de les variacions instantànies de freqüència i atenuació. La primera tècnica consistix en la discretización de la variació de la freqüència amb el temps, per mitjà d'una anàlisi basat en Short-Time Fourier Transform (STFT). La segona tècnica consistix en un ajust per mínims quadrats dels senyals de vibració a un model que considera les variacions de freqüència i atenuació amb el temps. La tercera tècnica empleada en esta tesi pot ser empleada per a l'avaluació d'estructures in situ. La tècnica es tracta d'un assaig acusto-elástico en règim dinàmic. En anglés Dynamic Acousto-Elastic Test (DAET). Les variacions del mòdul elàstic obtingudes per mitjà dels mètodes NIRAS i NSIRAS proporcionen un comportament mitjà i no permeten derivar les variacions del mòdul elàstic en un sol cicle de vibració. Actualment, la tècnica DAET és l'única que permet investigar tot el rang de fenòmens no lineals en el material. D'altra banda, a diferència d'altres tècniques DAET, en este estudi s'empra com contrast una ona contínua. L'ús d'una ona contínua permet investigar les variacions relatives del mòdul elàstic, per a un senyal transitori. A més, permet la inspecció d'elements per mitjà de l'accés per una sola cara.
Eiras Fernández, JN. (2016). Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/71439
TESIS
Premiado
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Ayvazyan, Vigen. "Etude de champs de température séparables avec une double décomposition en valeurs singulières : quelques applications à la caractérisation des propriétés thermophysiques des matérieux et au contrôle non destructif." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14671/document.
Повний текст джерелаАнотація:
La thermographie infrarouge est une méthode largement employée pour la caractérisation des propriétés thermophysiques des matériaux. L’avènement des diodes laser pratiques, peu onéreuses et aux multiples caractéristiques, étendent les possibilités métrologiques des caméras infrarouges et mettent à disposition un ensemble de nouveaux outils puissants pour la caractérisation thermique et le contrôle non desturctif. Cependant, un lot de nouvelles difficultés doit être surmonté, comme le traitement d’une grande quantité de données bruitées et la faible sensibilité de ces données aux paramètres recherchés. Cela oblige de revisiter les méthodes de traitement du signal existantes, d’adopter de nouveaux outils mathématiques sophistiqués pour la compression de données et le traitement d’informations pertinentes. Les nouvelles stratégies consistent à utiliser des transformations orthogonales du signal comme outils de compression préalable de données, de réduction et maîtrise du bruit de mesure. L’analyse de sensibilité, basée sur l’étude locale des corrélations entre les dérivées partielles du signal expérimental, complète ces nouvelles approches. L'analogie avec la théorie dans l'espace de Fourier a permis d'apporter de nouveaux éléments de réponse pour mieux cerner la «physique» des approches modales.La réponse au point source impulsionnel a été revisitée de manière numérique et expérimentale. En utilisant la séparabilité des champs de température nous avons proposé une nouvelle méthode d'inversion basée sur une double décomposition en valeurs singulières du signal expérimental. Cette méthode par rapport aux précédentes, permet de tenir compte de la diffusion bi ou tridimensionnelle et offre ainsi une meilleure exploitation du contenu spatial des images infrarouges. Des exemples numériques et expérimentaux nous ont permis de valider dans une première approche cette nouvelle méthode d'estimation pour la caractérisation de diffusivités thermiques longitudinales. Des applications dans le domaine du contrôle non destructif des matériaux sont également proposées. Une ancienne problématique qui consiste à retrouver les champs de température initiaux à partir de données bruitées a été abordée sous un nouveau jour. La nécessité de connaitre les diffusivités thermiques du matériau orthotrope et la prise en compte des transferts souvent tridimensionnels sont complexes à gérer. L'application de la double décomposition en valeurs singulières a permis d'obtenir des résultats intéressants compte tenu de la simplicité de la méthode. En effet, les méthodes modales sont basées sur des approches statistiques de traitement d'une grande quantité de données, censément plus robustes quant au bruit de mesure, comme cela a pu être observéInfrared thermography is a widely used method for characterization of thermophysical properties of materials. The advent of the laser diodes, which are handy, inexpensive, with a broad spectrum of characteristics, extend metrological possibilities of infrared cameras and provide a combination of new powerful tools for thermal characterization and non destructive evaluation. However, this new dynamic has also brought numerous difficulties that must be overcome, such as high volume noisy data processing and low sensitivity to estimated parameters of such data. This requires revisiting the existing methods of signal processing, adopting new sophisticated mathematical tools for data compression and processing of relevant information.New strategies consist in using orthogonal transforms of the signal as a prior data compression tools, which allow noise reduction and control over it. Correlation analysis, based on the local cerrelation study between partial derivatives of the experimental signal, completes these new strategies. A theoretical analogy in Fourier space has been performed in order to better understand the «physical» meaning of modal approaches.The response to the instantaneous point source of heat, has been revisited both numerically and experimentally. By using separable temperature fields, a new inversion technique based on a double singular value decomposition of experimental signal has been introduced. In comparison with previous methods, it takes into account two or three-dimensional heat diffusion and therefore offers a better exploitation of the spatial content of infrared images. Numerical and experimental examples have allowed us to validate in the first approach our new estimation method of longitudinal thermal diffusivities. Non destructive testing applications based on the new technique have also been introduced.An old issue, which consists in determining the initial temperature field from noisy data, has been approached in a new light. The necessity to know the thermal diffusivities of an orthotropic medium and the need to take into account often three-dimensional heat transfer, are complicated issues. The implementation of the double singular value decomposition allowed us to achieve interesting results according to its ease of use. Indeed, modal approaches are statistical methods based on high volume data processing, supposedly robust as to the measurement noise
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Chvatík, Štěpán. "Asynchronní motor s vnějším rotorem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377075.
Повний текст джерелаКниги з теми "Thermal NDT methods"
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Dolgov, I., Mihail Volovik, and Andrey Mahnovskiy. Thermographic signs of certain diseases of the respiratory system (acute sinusitis, pneumonia) Thermography Atlas. ru: INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/textbook_61b1ab7de6b1f9.69203696.
Повний текст джерелаАнотація:
The present issue focuses on the practice of medical thermal imaging in patients with paranasal sinusitis and pneumonia. The description of thermograms is based on a quantitative analysis of temperature gradients and trends in temperature of different body regions (Projection «head front» for paranasal sinusitis, «breast front» and «back», in a defined layout formed in «cloud» thermograms analysis program "Tvision" of «Dignosis», Russia) with values of thermographic markers that demonstrated their differentiating capabilities when compared with reference methods. Thus, the thermographic conclusion is formed not simply by thermal phenomenon «hot-cold», but on the basis of numerical values of markers, which indicate hypothetical nosological diagnosis and significantly simplifies the algorithm for those physicians who use this method as an additional.
The publication is intended for doctors of any speciality who, in their daily clinical practice, treat the patients with suspicions disease of respiratory system
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Schroeder, Daniel V. An Introduction to Thermal Physics. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192895547.001.0001.
Повний текст джерелаАнотація:
Thermal physics deals with collections of large numbers of particles—typically 1023 or so. Examples include the air in a balloon, the water in a lake, the electrons in a chunk of metal, and the photons given off by the sun. We can't possibly follow every detail of the motions of so many particles. So in thermal physics we assume that these motions are random, and we use the laws of probability to predict how the material as a whole ought to behave. Alternatively, we can measure the bulk properties of a material, and from these infer something about the particles it is made of. This book will give you a working understanding of thermal physics, assuming that you have already studied introductory physics and calculus. You will learn to apply the general laws of energy and entropy to engines, refrigerators, chemical reactions, phase transformations, and mixtures. You will also learn to use basic quantum physics and powerful statistical methods to predict in detail how temperature affects molecular speeds, vibrations of solids, electrical and magnetic behaviors, emission of light, and exotic low-temperature phenomena. The problems and worked examples explore applications not just within physics but also to engineering, chemistry, biology, geology, atmospheric science, astrophysics, cosmology, and everyday life.
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Coppola, Silvia, and Franco Valenza. Inhalation injury in the ICU. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0107.
Повний текст джерелаАнотація:
Inhalation injury represents one of the most serious associated injuries complicating the care of thermally-injured patient. It can result in severe respiratory failure and acute respiratory distress syndrome (ARDS) by three mechanisms—thermal or chemical injury, and impairment of systemic oxygen supply. Thermal injury can cause erythema, ulceration, and progressive, life-threatening oedema, particularly of the upper airways. Chemical injury is due to irritants or cytotoxic compounds, and depends on the material burned, the temperature of the fire, and the amount of oxygen present in the fire environment. It is responsible for irritation, ulceration, and oedema of the mucosal surface, and the initiation of a lung inflammatory reaction when small particles reach the alveoli. Moreover, the increased vascular permeability, and the reduced surfactant production carry a significant risk in the development of pneumonia and ARDS. Bronchospasm and upper airway oedema can occur rapidly, while lower airway oedema can be asymptomatic for up to 24 hours. Lung imaging techniques may not reveal injured areas for the first 24–48 hours. Fibre optic bronchoscopy is considered to be the most direct diagnostic method for the definitive diagnosis of inhalation injury. The patient management includes airways assessment, adequate fluid resuscitation, and mechanical ventilation when required. All victims of smoke inhalation should be always evaluated for cyanide and carbon monoxide poisoning.
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Durakov, I. A., and L. N. Mylnikova. At the Dawn of Metallurgy: Bronze Casting Production of the Ob-Irtysh Forest-Steppe Population in the Early Bronze Age. IAET SB RAS Publishing, 2021. http://dx.doi.org/10.17746/7803-0318-3.2021.
Повний текст джерелаАнотація:
Th e monograph is devoted to the problems of studying the bronze casting production of the Ust-Tartasskaya, the Odinovskaya and the Krotovskaya cultures of the Barabinsk forest-steppe Early Bronze Age. Th e work was carried out within the framework of an integrated analytical approach, which includes the use of traditional archaeological methods and data obtained as a result of the application of natural sciences methods. A method for determining the functional purpose of technical ceramics fragments is proposed. Th e archaeological context of the fi nds is described in detail and the characteristics of the bronze casting sites are given. Products of the foundry set of production equipment are represented by fragments of nozzles, molds and crucibles. For each item, full descriptions, analogies, the results of binocular analysis of molding masses and thermal studies are given. An assessment to the cultural, chronological and innovative traditions of bronze casting in certain periods of the Bronze Age is given. Th e book is addressed to specialists-archaeologists, ethnographers and everyone who is interested in the most ancient industries among the population of Siberia.
Частини книг з теми "Thermal NDT methods"
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Tserpes, Konstantinos, Elli Moutsompegka, Mareike Schlag, Kai Brune, Christian Tornow, Ana Reguero Simón, and Romain Ecault. "Characterization of Pre-bond Contamination and Aging Effects for CFRP Bonded Joints Using Reference Laboratory Methods, Mechanical Tests, and Numerical Simulation." In Adhesive Bonding of Aircraft Composite Structures, 51–117. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-319-92810-4_2.
Повний текст джерелаАнотація:
AbstractIn this chapter, the pre-bond contamination and ageing effects on carbon fiber reinforced plastic (CFRP) adherends and CFRP bonded joints are characterized by means of reference laboratory non-destructive testing (NDT) methods, mechanical tests, and numerical simulation. Contaminations from two fields of application are considered, namely in aircraft manufacturing (i.e. production) and for in-service bonded repair. The production-related scenarios comprise release agent, moisture, and fingerprint, while the repair-related scenarios comprise fingerprint, thermal degradation, de-icing fluid, and a faulty curing of the adhesive. For each scenario, three different levels of contamination were pre-set and applied, namely low, medium and high level. Furthermore, two types of samples were tested, namely coupons and pilot samples (a stiffened panel and scarf repairs). The CFRP adherends were contaminated prior to bonding and the obtained surfaces were characterized using X-ray photoelectron spectroscopy. After bonding, the joints were tested by ultrasonic testing. To characterize the effects of each contamination on the strength of the bonded joints, mode-I and mode-II fracture toughness tests, and novel centrifuge tests were conducted on the coupons, while tensile tests were performed on the scarfed samples. Additionally, numerical simulation was performed on CFRP stiffened panels under compression using the LS-DYNA finite element (FE) platform.
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Kumarapu, Kumar, M. Shashi, and K. Venkata Reddy. "Development of Thermal Remote Sensing NDT Method for Early Age Strength Estimation of Concrete." In Advances in Sustainable Construction Materials, 211–22. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3361-7_16.
Повний текст джерела
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Bracci, D. J., P. Garikepati, D. C. Jiles, and O. Buck. "NDE Methods for Determination of Thermal History and Mechanical Properties of Al-Li Alloys." In Review of Progress in Quantitative Nondestructive Evaluation, 1395–402. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1893-4_157.
Повний текст джерела
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Bracci, D. J., P. Garikepati, D. C. Jiles, and O. Buck. "Search for NDE Methods to Characterize Thermal History and Mechanical Properties of Al-Li Alloys." In Review of Progress in Quantitative Nondestructive Evaluation, 1255–62. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0979-6_45.
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Samuelsson, Anders, Falko Schröter, Gerhard Sedlacek, Christian Müller, Alain Nussbaumer, Bernt Johansson, Torsten Höglund, Peter Collin, and Alberto Miazzon. "High-Performance Steels in Europe." In Use and Application of High-Performance Steels for Steel Structures, 99–146. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2005. http://dx.doi.org/10.2749/sed008.099.
Повний текст джерелаАнотація:
<p>Since the first application of steel in steel structures in the 19th century the development of steel construction has been closely linked to the development in material properties and production methods. Significant achievements concerning strength, economy, design versatility, fabrication and erection techniques and service performance would not have been possible without the substantial improvements of steel. Especially with the application of "new" production processes for carbon steels such as the thermo-mechanical rolling and the quenching and tempering process, steel with a high construction strength but guaranteeing also good fabrication properties such as weldability was introduced into the construction market.</p>
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"Thermal methods." In Emerging Technologies in NDT, 189–226. CRC Press, 2008. http://dx.doi.org/10.1201/9781482266269-11.
Повний текст джерела
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Matysík, M., I. Plšková, and Z. Chobola. "Detection of concrete thermal load time by acoustic NDT methods." In Advances and Trends in Engineering Sciences and Technologies III, 191–96. CRC Press, 2019. http://dx.doi.org/10.1201/9780429021596-30.
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Lee, P. J. "Other Assessment Methods—An Overview." In Statistical Methods for Estimating Petroleum Resources, edited by Jo Anne DeGraffenreid. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195331905.003.0013.
Повний текст джерелаАнотація:
Resource evaluation procedures have evolved along distinct paths, involving a variety of statistical, geochemical, and geological approaches because of different types of data and various assumptions that have driven their development. Many methods have been developed so far, but only those methods that have been published and have significantly influenced subsequent development of evaluation procedures are discussed here. The purpose of this chapter is to present an overview of the principles of these methods and identify the direction of future research in this area. Methods discussed include the following: • Geological approach—volumetric yield by analogy, basin classification • Geochemical approach—petroleum systems, burial and thermal history • Statistical approach (methods that were not discussed in previous chapters are discussed here) • Finite population methods—Arps and Roberts’, Bickel’s, Kaufman’s anchored, and Chen and Sinding–Larsen’s geoanchored • Superpopulation methods—USGS log-geometric, Zipf’s law, creaming, and Long’s • The regression method • The fractal method Specific data and assumptions can be applied to each of these methods. Some of the assumptions can be validated by the data whereas others cannot. These methods have their own merits and disadvantages. The geological approach has been used for the past several decades and is a qualitative method. This section discusses the volumetric yield method and the basin classification method. Volumetric yield using the analogous basin method was the earliest method of petroleum resource evaluation applied to frontier basins. It requires knowledge of the volume of a basin and its characteristics (e.g., tectonic, sedimentation, thermal generation, migration, and accumulation). Based on comparative studies, geologists are able to apply a hydrocarbon yield factor per unit volume (i.e., barrels of oil/cubic unit of sediment) from one known basin to an unknown basin with similar characteristics. Thus, for conceptual basins, this provides some information about the richness of an unknown basin. The advantages are the following: 1. It is suitable for the evaluation of conceptual basins. 2. It is easy to understand. 3. It combines geochemical data and/or experience from mature basins.
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Satapathy, Suchismita, and Jitendra Narayan Biswal. "Thermal Power Sector Sustainability." In Handbook of Research on Ergonomics and Product Design, 381–401. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5234-5.ch021.
Повний текст джерелаАнотація:
Sustainable supply chain management (SSCM) practices in thermal power plants is dependent on mostly three pillars: social factor, economic factor, and environmental factor. So, in this chapter, sustainable supply chain management of Indian thermal power sector is evaluated. Artificial neural network (ANN) method is implemented to measure whether the benefits of sustainable supply chain management are achieved after practices of sustainable supply chain management in Indian thermal power sector. This chapter also designs a framework by QFD (quality function deployment) method to find solution for some unsatisfactory measures (inputs in sustainable factors) that are not achieved against outputs. As sustainable supply chain management practices in thermal power plants are influenced by a significant number of interrelated enablers and barriers, the drivers or enablers of SSCM are taken as the design requirement to improve SSCM in thermal power industries, and the most important driver is prioritized against the unsatisfied measurands in thermal power sector.
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Bakalos, Nikolaos, Iason Katsamenis, Eleni Eirini Karolou, and Nikolaos Doulamis. "Unsupervised Man Overboard Detection Using Thermal Imagery and Spatiotemporal Autoencoders." In Frontiers in Artificial Intelligence and Applications. IOS Press, 2021. http://dx.doi.org/10.3233/faia210103.
Повний текст джерелаАнотація:
Man overboard incidents in a maritime vessel are serious accidents where the rapid detection of the even is crucial for the safe retrieval of the person. To this end, the use of deep learning models as automatic detectors of these scenarios has been tested and proven efficient, however, the use of correct capturing methods is imperative in order for the learning framework to operate well. Thermal data can be a suitable method of monitoring, as they are not affected by illumination changes and are able to operate in rough conditions, such as open sea travel. We investigate the use of a convolutional autoencoder trained over thermal data, as a mechanism for the automatic detection of man overboard scenarios. Morever, we present a dataset that was created to emulate such events and was used for training and testing the algorithm.
Тези доповідей конференцій з теми "Thermal NDT methods"
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Florin, Christian. "Thermal Testing Methods As New Tool In NDT." In Technical Symposium Southeast, edited by Robert P. Madding. SPIE, 1987. http://dx.doi.org/10.1117/12.940498.
Повний текст джерела
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Pelletier, J. F., E. Grinzato, R. Dessi, and X. Maldague. "Shape and uneven heating correction for NDT on cylinders by thermal methods." In 1996 Quantitative InfraRed Thermography. QIRT Council, 1996. http://dx.doi.org/10.21611/qirt.1996.043.
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Ivashov, Sergey I., Vladimir V. Razevig, Andrey V. Zhuravlev, Timothy Bechtel, and Margarita A. Chizh. "Comparison of Different NDT Methods in Diagnostics of Rocket Cryogenic Tanks Thermal Protection Coating." In 2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS). IEEE, 2019. http://dx.doi.org/10.1109/comcas44984.2019.8958157.
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Luz, A. M. G., D. Balint, and K. Nikbin. "A Multiscale NDT System for Damage Detection in Thermal Barrier Coatings." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10694.
Повний текст джерелаАнотація:
Progress in aero-engines and land-based gas turbines is continuously linked with a rise of the operating temperature. TBCs are multilayered structures which function together to effectively lower the temperature of its load-bearing superalloy substrate while simultaneously providing oxidation protection against high temperature combustion environments during operation. They typically comprise of a ceramic top coat for thermal insulation and a metallic bond coat that provides oxidation/corrosion resistance and enhances the adhesion of the YSZ to the superalloy substrate. Due to high-temperature oxidation of the bond coat, a thermally grown oxide (TGO) scale of continuous Al2O3 is formed between the ceramic top coat and the bond coat. The formation and growth of the TGO increases the mismatch of thermal expansion coefficients among the multilayered TBC and induce high thermal stresses leading to spallation of the YSZ coat from the underlying metal. Hence, nondestructive diagnostic tools that could reliably probe the subsurface damage state of TBCs are essential to take full advantage of these systems. In this contribution, a new concept of multiscale NDT system is presented. The instrument uses a combination of imaging-based methods with photoluminescence piezospectroscopy, a laser-based method. Imaging-based methods like mid-infrared reflectance, laser optical backscatter and infrared tomography were used to predict the overall lifetime of the coated component. When TBCs approach the end of life, micro-crack nucleation and propagation at the top coat/bond coat interface increases the amount of reflected light. This rise in reflectance was correlated with the lifetime of the component using a neural network that merges the mean and standard deviation value of the gray level. Photoluminescence piezospectroscopy was subsequently used to give information about the structural integrity of the hot spots identified in the image analysis. This laser-based technique measures in-situ the residual stress in the TGO at room temperature. Damage leads to a relaxation of the local stress which is in turn reflected in the luminescence spectrum shape. However, presently there is no agreement on the best spectral parameters that should be used as a measure of the damage accumulation in the coatings. Therefore, the evolution of luminescence spectrum from as-manufactured to critically damaged TBCs was determined using the finite element method. This approach helped to identify the most suitable spectral parameters for damage detection, improving the reliability of photoluminescence piezospectroscopy as a failure assessment tool for TBCs.
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Lugscheider, E., P. Remer, C. Herbst, and G. Barbezat. "A Potential NDT Method for Rapid Quality Control of Thermal Sprayed Coatings." In ITSC 1996, edited by C. C. Berndt. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.itsc1996p0933.
Повний текст джерелаАнотація:
Abstract An overview on potential non-destructive testing (NDT) methods for the inspection of thermally sprayed coatings in production lines is given. The suitability of several NDT techniques has been investigated with view on their sensitivity for the detection of defect sizes possibly being critical for Thermal Spray coatings. Eventually, a method is presented that shows qualification for detection of subsurface flaws in coatings such as delaminations and cracks and offers flaw distinction by image analysis procedures. A storage and archiving of test results is possible thus completing full quality control and meeting possible warranty claims. The major advantage of the NDT process is its very high detection speed which guarantees high productivity even for high volume production systems. Thus a full-area detection of large coated components becomes possible. The process is not restricted to plain components, but is usable for the detection of internally coated cylinders as well.
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Walaszek, Henri. "Impact of New Imaging Non Destructive Methods in Testing and Monitoring of Composite and Metallic Components." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-98136.
Повний текст джерелаАнотація:
The non-destructive testing techniques (NDT) are now undergoing significant changes associated with the development of new sensors and digital techniques for storing and processing information. Thus, new ultrasonic methods now provide a view of the entire component in the form of a traceable image. These new methods include ultrasonic TOFD methods (to inspect metal products), and the Phased Array method (metallic and composite products), which can image the inside of components. The simulation of ultrasonic testing brings a strong contribution in ultrasonic inspection preparation. Another major trend of the development of NDT methods is the rise of active thermal infrared methods, enabling high resolution imaging of surface and near surface defects of components. A remarkable application of new radiographic technology consists also in Computed Tomography, which now allows 3D imaging within the mechanical components. These technologies are now available in the market with affordable prices, to test more reliably and faster the health of mechanical components. Thus, it helps to increase the quality of components, especially in the Pressure Vessel and piping industry, and to improve the safety of industrial pressure equipment. Developments in the more advanced testing methods are presented, with examples of applications on pressure vessel and piping components.
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Tian, Gui Yun, Liang Cheng, Yuhua Cheng, and Fan Yang. "Electromagnetic Non-Destructive Evaluation for Safety Critical Components and Material." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16858.
Повний текст джерелаАнотація:
After review of defects in nuclear reactor plants, this paper exhibits novel electromagnetic (EM) non-destructive testing and evaluation (NDT & E) for defect and material characterisation of nuclear fuel materials. Through comparison with traditional method for nuclear material inspection, e.g. X-Ray and phase array, EM NDT&E show advantages in non-contact inspection. Several recent development EM NDT & E techniques are reported and several case studies are investigated and discussed. Results show pulsed eddy current (PEC) can measure the stress and defect via the normalised ΔBZ features. The bigger stress results in the larger amplitude on normalised ΔBZ response. Magnetic Barkenhasuen noise (MBN) can measure the strain status via the RMS of Barkhausen noise amplitude. The RMS value decreases as the increase in strain. Eddy current pulsed thermography (ECPT) can be used for welding detection and characterisation through ‘highlighting’ the welding in thermal images. ECPT and MBN methods are also compared with traditional X-Ray and phase array methods for the inspection of welding samples. The comparison shows the competitive capability of ECPT in welding detection and evaluation. This paper demonstrates PEC, MBN and ECPT as good candidates for nuclear fuel materials.
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Furlong, Cosme, and Ryszard J. Pryputniewicz. "Novel Experimental-Computational Method for Quantitative Applications in Electronic Packaging." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/epp-24732.
Повний текст джерелаАнотація:
Abstract Rapid advances in microelectronics require design and optimization of components and packages, for new and ever more demanding applications, in relatively short periods of time while satisfying electrical, thermal, and mechanical specifications, as well as cost and manufacturability expectations. In addition, reliability and durability have to be taken into consideration. As a consequence, some of the most sophisticated analytical, computational, and experimental methods are being used for development, optimization, and quantitative characterization of electronic packages. In this paper, a novel experimental-computational method, based on combined use of recent advances in laser-based optics and computational modeling, is described and its application is demonstrated by case studies of microelectronic components subjected to electro-thermo-mechanical loads. Results of these studies show that this methodology provides an effective engineering tool for nondestructive testing (NDT) applications in electronic packaging and provides indispensable quantitative data for development, optimization, and applications in electronic packaging.
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Hossain, Md Shahjahan, Russell Krenek, Hossein Taheri, and Fadwa Dababneh. "Ultrasonic Phased Array Technique for Defect Detection and Sizing in Heavy-Walled Cast Components." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23319.
Повний текст джерелаАнотація:
Abstract Cast metal parts are extensively found in many engineering products such as pump casing and engines. Thermal effects exhibited during metal casting processes, such as solidification can generate defects in the cast components. Effective nondestructive testing (NDT) for detection and sizing of defects in cast parts prevents extra cost and time associated with repair and maintenance. Surface-breaking cracks and porosity are among the common types of defects in large cast components. There are several limitations in using conventional NDT methods for as built cast parts due to surface conditions, coarse-grain structure, and characteristics of potential defects. Ultrasonic adaptive imaging based on the Phased Array Ultrasonic Testing (PAUT) technology is proposed for coarse-grain heavy-walled cast material inspection. The capability of aperture focusing in PAUT provides the opportunity for better imaging results. A comprehensive understanding about the ultrasonic beam focusing and the selection of an appropriate transducer and wedges is necessary for successful defect characterization. Cast aluminum and iron samples having on-purpose made defects were successfully inspected using the PAUT. Unlike conventional techniques, the results indicated that the PAUT is a promising method for inspecting as-built cast parts with rough surface finish conditions. The proposed method helps to decrease the inspection time, machining requirements, and preparation costs. Moreover, the enhanced defect sizing approach provides useful information for repair and maintenance decision making such as amount of material grinding and post-welding procedure.
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Meyendorf, Norbert G., Jochen Hoffmann, Liming Shen, and Henrik Rösner. "Trends in NDE Using Thermal Inspection Methods." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/nde-25810.
Повний текст джерелаАнотація:
Abstract This paper gives a brief overview of present NDE techniques that use infrared cameras. Starting with physical basics, current state of the art and future trends are discussed. Two new methods for materials characterization that use heat dissipation and hot air for heat stimulation will be presented. A new technique called fan thermography, has high potential for corrosion detection under intact coatings. Using this technique, low-cost uncooled infrared cameras are sufficient for obtaining excellent, highly sensitive imaging results.
Звіти організацій з теми "Thermal NDT methods"
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Clausen, Jay, Christopher Felt, Michael Musty, Vuong Truong, Susan Frankenstein, Anna Wagner, Rosa Affleck, Steven Peckham, and Christopher Williams. Modernizing environmental signature physics for target detection—Phase 3. Engineer Research and Development Center (U.S.), March 2022. http://dx.doi.org/10.21079/11681/43442.
Повний текст джерелаАнотація:
The present effort (Phase 3) builds on our previously published prior efforts (Phases 1 and 2), which examined methods of determining the probability of detection and false alarm rates using thermal infrared for buried object detection. Environmental phenomenological effects are often represented in weather forecasts in a relatively coarse, hourly resolution, which introduces concerns such as exclusion or misrepresentation of ephemera or lags in timing when using this data as an input for the Army’s Tactical Assault Kit software system. Additionally, the direct application of observed temperature data with weather model data may not be the best approach because metadata associated with the observations are not included. As a result, there is a need to explore mathematical methods such as Bayesian statistics to incorporate observations into models. To better address this concern, the initial analysis in Phase 2 data is expanded in this report to include (1) multivariate analyses for detecting objects in soil, (2) a moving box analysis of object visibility with alternative methods for converting FLIR radiance values to thermal temperature values, (3) a calibrated thermal model of soil temperature using thermal IR imagery, and (4) a simple classifier method for automating buried object detection.
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Scobie, Linda, Liam O'Connor, Martin D’Agostino, Nigel Cook, Jonathan Wells, Sarah Berry, Louise Kelly, Anne Wood, and Sue Keenan. Thermal Inactivation Model for Hepatitis E Virus (HEV). Food Standards Agency, February 2022. http://dx.doi.org/10.46756/sci.fsa.sdt366.
Повний текст джерелаАнотація:
Hepatitis E is an emerging issue, with the number of confirmed cases in the UK increasing in 2009-2015, and decreasing slightly in 2016 and 2017. There is some epidemiological evidence of an association of this virus with undercooked pork and pork products. Currently, there is no standardized method for evaluating thermal stability of HEV and also a lack of a suitable assay that can distinguish between intact HEV that can cause an infection and damaged virus which is not capable of causing an infection. This has raised concerns as it is extremely difficult to extrapolate the risk from pork products in relation to cooking practices. We are seeking to address this knowledge gap, which will not only inform our risk assessment, but will also provide an indication if cooking is sufficient to inactivate the virus in foods
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Rouseff, Russell L., and Michael Naim. Characterization of Unidentified Potent Flavor Changes during Processing and Storage of Orange and Grapefruit Juices. United States Department of Agriculture, September 2002. http://dx.doi.org/10.32747/2002.7585191.bard.
Повний текст джерелаАнотація:
Citrus juice flavor quality traditionally diminishes after thermal processing and continuously during storage. Our prior studies found that four of the five most potent off-aromas formed during orange juice storage had not been identified. The primary emphasis of this project was to characterize and identify those potent flavor degrading aroma volatiles so that methods to control them could be developed and final flavor quality improved. Our original objectives included: 1 Isolate and characterize the most important unidentified aroma impact compounds formed or lost during pasteurization and storage. 2. Determination of thiamine and carotenoid thermal decomposition and Strecker degradation pathways in model solutions as possible precursors for the unidentified off-flavors. 3. Evaluate the effectiveness of an "electronic nose" to differentiate the headspace aromas of from untreated and heat pasteurized orange and grapefruit juices. 4. Use model systems of citrus juices to investigate the three possible precursor pathways (from 2) for flavor impact compounds formed or lost during pasteurization or storage. RESULTS - The components responsible for citrus storage off flavors and their putative precursors have now been identified. Certain carotenoids (b-carotene) can thermally degrade to produce b-ionone and b-damascenone which are floral and tobacco smelling respectively. Our GC-O and sensory experiments indicated that b-damascenone is a potential storage off-flavor in orange juice. Thiamine (Vitamin B1) degradation produces 2-methyl-3-furan thiol, MFT, and its dimer bis(2- methyl-3-furyl) disulfide which both produce meaty, savory aromas. GC-O and sensory studies indicated that MFT is another storage off-flavor. Methional (potato aroma) is another off flavor produced primarily from the reaction of the native amino acid, methionine, and oxidized ascorbic acid (vitamin C). This is a newly discovered pathway for the production of methional and is more dominant in juices than the classic Maillard reaction. These newly identified off flavors diminish the flavor quality of citrus juices as they distort the flavor balance and introduce non-typical aromas to the juice flavor profile. In addition, we have demonstrated that some of the poor flavor quality citrus juice found in the market place is not only from the production of these and other off flavors but also due to the absence of desirable flavor components including several potent aldehydes and a few esters. The absence of these compounds appears to be due to incomplete flavor volatile restoration after the making of juice concentrates. We are the first to demonstrate that not all flavor volatiles are removed along with water in the production of juice concentrate. In the case of grapefruit juice we have documented which flavor volatiles are completely removed, which are partially removed and which actually increase because of the thermal process. Since more that half of all citrus juices is made into concentrate, this information will allow producers to more accurately restore the original flavor components and produce a juice with a more natural flavor. IMPLICATIONS - We have shown that the aroma of citrus juices is controlled by only 1-2% of the total volatiles. The vast majority of other volatiles have little to no direct aroma activity. The critical volatiles have now been identified. The ability to produce high quality citrus juices requires that manufacturers know which chemical components control aroma and flavor. In addition to identifying the critical flavor components (both positive and negative), we have also identified several precursors. The behavior of these key aroma compounds and their precursors during common manufacturing and storage conditions has been documented so manufacturers in Israel and the US can alter production practices to minimize the negative ones and maximize the positive ones.
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Weinschenk, Craig, Keith Stakes та Robin Zevotek. Impact of Fire Attack Utilizing Interior and Exterior Streams on Firefighter Safety and Occupant Survival: Air Entrainment. UL Firefighter Safety Research Institute, грудень 2017. http://dx.doi.org/10.54206/102376/gmax3657.
Повний текст джерелаАнотація:
As research continues into how fire department interventions affect fire dynamics in the modern fire environment, questions continue to arise on the impact and implications of interior versus exterior fire attack on both firefighter safety and occupant survivability. Previous research into various types of fire ground ventilation, flow paths, and exterior fire streams has provided the fire service with an increased understanding of fire dynamics. However, in some instances, the information from the studies did not support current, experience-based practices. This gap between the research to date and the fire ground suppression experience has driven the need for further study. This study will build upon the fire research conducted to date by analyzing how firefighting tactics, specifically different fire suppression tools and tactics, affect the thermal exposure and survivability of both firefighters and building occupants and affect fire behavior in structures. The purpose of this study is to improve firefighter safety, fire ground tactics, and the knowledge of fire dynamics by providing the fire service with scientific information, developed from water flow and full-scale fire testing, in representative single-family homes. This study will build and expand upon the fire research conducted to date by analyzing how firefighting tactics, specifically suppression methods, affect the thermal exposure and survivability of both firefighters and building occupants in addition to impacting fire behavior in structures. The purpose of this study is to improve firefighter safety, fireground tactics, and the knowledge of fire dynamics by providing the fire service with credible scientific information, developed from both water flow and full-scale fire testing, in representative single family homes. The project is comprised of 3 parts: • Part I: Water Distribution • Part II: Air Entrainment • Part III: Full-Scale Residential Fire Experiments This report details the results and analysis from the air entrainment testing. These tests were conducted without the presence of fire to gain a fundamental understanding of how hose streams entrain air. Each set of experiments was intended to add to the understanding of air entrainment and pressure from fire service hose streams by evaluating the differences caused by various application methods, hose stream types, nozzle movements, pressures/flow rates, manufacturers, and ventilation configurations.
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Friedman, Shmuel, Jon Wraith, and Dani Or. Geometrical Considerations and Interfacial Processes Affecting Electromagnetic Measurement of Soil Water Content by TDR and Remote Sensing Methods. United States Department of Agriculture, 2002. http://dx.doi.org/10.32747/2002.7580679.bard.
Повний текст джерелаАнотація:
Time Domain Reflectometry (TDR) and other in-situ and remote sensing dielectric methods for determining the soil water content had become standard in both research and practice in the last two decades. Limitations of existing dielectric methods in some soils, and introduction of new agricultural measurement devices or approaches based on soil dielectric properties mandate improved understanding of the relationship between the measured effective permittivity (dielectric constant) and the soil water content. Mounting evidence indicates that consideration must be given not only to the volume fractions of soil constituents, as most mixing models assume, but also to soil attributes and ambient temperature in order to reduce errors in interpreting measured effective permittivities. The major objective of the present research project was to investigate the effects of the soil geometrical attributes and interfacial processes (bound water) on the effective permittivity of the soil, and to develop a theoretical frame for improved, soil-specific effective permittivity- water content calibration curves, which are based on easily attainable soil properties. After initializing the experimental investigation of the effective permittivity - water content relationship, we realized that the first step for water content determination by the Time Domain Reflectometry (TDR) method, namely, the TDR measurement of the soil effective permittivity still requires standardization and improvement, and we also made more efforts than originally planned towards this objective. The findings of the BARD project, related to these two consequential steps involved in TDR measurement of the soil water content, are expected to improve the accuracy of soil water content determination by existing in-situ and remote sensing dielectric methods and to help evaluate new water content sensors based on soil electrical properties. A more precise water content determination is expected to result in reduced irrigation levels, a matter which is beneficial first to American and Israeli farmers, and also to hydrologists and environmentalists dealing with production and assessment of contamination hazards of this progressively more precious natural resource. The improved understanding of the way the soil geometrical attributes affect its effective permittivity is expected to contribute to our understanding and predicting capability of other, related soil transport properties such as electrical and thermal conductivity, and diffusion coefficients of solutes and gas molecules. In addition, to the originally planned research activities we also investigated other related problems and made many contributions of short and longer terms benefits. These efforts include: Developing a method and a special TDR probe for using TDR systems to determine also the soil's matric potential; Developing a methodology for utilizing the thermodielectric effect, namely, the variation of the soil's effective permittivity with temperature, to evaluate its specific surface area; Developing a simple method for characterizing particle shape by measuring the repose angle of a granular material avalanching in water; Measurements and characterization of the pore scale, saturation degree - dependent anisotropy factor for electrical and hydraulic conductivities; Studying the dielectric properties of cereal grains towards improved determination of their water content. A reliable evaluation of the soil textural attributes (e.g. the specific surface area mentioned above) and its water content is essential for intensive irrigation and fertilization processes and within extensive precision agriculture management. The findings of the present research project are expected to improve the determination of cereal grain water content by on-line dielectric methods. A precise evaluation of grain water content is essential for pricing and evaluation of drying-before-storage requirements, issues involving energy savings and commercial aspects of major economic importance to the American agriculture. The results and methodologies developed within the above mentioned side studies are expected to be beneficial to also other industrial and environmental practices requiring the water content determination and characterization of granular materials.
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Weinschenk, Craig, Keith Stakes та Robin Zevotek. Impact of Fire Attack Utilizing Interior and Exterior Streams on Firefighter Safety and Occupant Survival: Water Mapping. UL Firefighter Safety Research Institute, грудень 2017. http://dx.doi.org/10.54206/102376/nevx1787.
Повний текст джерелаАнотація:
As research continues into how fire department interventions affect fire dynamics in the modern fire environment; questions continue to arise on the impact and implications of interior versus exterior fire attack on both firefighter safety and occupant survivability. Previous research into various types of fire ground ventilation, flow paths, and exterior fire streams has provided the fire service with an increased understanding of fire dynamics. However, in some instances, the information from the studies may not support current, experienced-based practices. This gap between the research to date and the fire ground suppression experience has driven the need for further study. Therefore, research into the various methods of fire attack will allow a broader understanding of how firefighter interventions on the fire ground can impact the outcome of both life safety and property protection. This study will build upon the fire research conducted to date by analyzing how firefighting tactics, specifically different fire suppression tools and tactics, affect the thermal exposure and survivability of both firefighters and building occupants and affect fire behavior in structures. The purpose of this study is to improve firefighter safety, fireground tactics, and the knowledge of fire dynamics by providing the fire service with scientific information, developed from water flow and full-scale fire testing, in representative single-family homes. The project will be comprised of 3 parts: • Part I: Water Distribution • Part II: Air Entrainment • Part III: Full-Scale Residential Fire Experiments This report details the results and analysis from the water distribution experiments. These tests were conducted without the presence of fire to gain a fundamental understanding of water flows into compartments. Each test was designed to quantify water distribution within a compartment by evaluating the differences caused by various application methods, hose stream types, nozzle movements, pressures/flow rates, stream locations and elevation angles.
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Hutchinson, M. L., J. E. L. Corry, and R. H. Madden. A review of the impact of food processing on antimicrobial-resistant bacteria in secondary processed meats and meat products. Food Standards Agency, October 2020. http://dx.doi.org/10.46756/sci.fsa.bxn990.
Повний текст джерелаАнотація:
For meat and meat products, secondary processes are those that relate to the downstream of the primary chilling of carcasses. Secondary processes include maturation chilling, deboning, portioning, mincing and other operations such as thermal processing (cooking) that create fresh meat, meat preparations and ready-to-eat meat products. This review systematically identified and summarised information relating to antimicrobial resistance (AMR) during the manufacture of secondary processed meatand meat products (SPMMP). Systematic searching of eight literature databases was undertaken and the resultantpapers were appraised for relevance to AMR and SPMMP. Consideration was made that the appraisal scores, undertaken by different reviewers, were consistent. Appraisal reduced the 11,000 initially identified documents to 74, which indicated that literature relating to AMR and SPMMP was not plentiful. A wide range of laboratory methods and breakpoint values (i.e. the concentration of antimicrobial used to assess sensitivity, tolerance or resistance) were used for the isolation of AMR bacteria.The identified papers provided evidence that AMR bacteria could be routinely isolated from SPMMP. There was no evidence that either confirmed or refuted that genetic materials capable of increasing AMR in non-AMR bacteria were present unprotected (i.e. outside of a cell or a capsid) in SPMMP. Statistical analyses were not straightforward because different authors used different laboratory methodologies.However, analyses using antibiotic organised into broadly-related groups indicated that Enterobacteriaceaeresistant to third generation cephalosporins might be an area of upcoming concern in SPMMP. The effective treatment of patients infected with Enterobacteriaceaeresistant to cephalosporins are a known clinical issue. No AMR associations with geography were observed and most of the publications identified tended to be from Europe and the far east.AMR Listeria monocytogenes and lactic acid bacteria could be tolerant to cleaning and disinfection in secondary processing environments. The basis of the tolerance could be genetic (e.g. efflux pumps) or environmental (e.g. biofilm growth). Persistent, plant resident, AMR L. monocytogenes were shown by one study to be the source of final product contamination. 4 AMR genes can be present in bacterial cultures used for the manufacture of fermented SPMMP. Furthermore, there was broad evidence that AMR loci could be transferred during meat fermentation, with refrigeration temperatures curtailing transfer rates. Given the potential for AMR transfer, it may be prudent to advise food business operators (FBOs) to use fermentation starter cultures that are AMR-free or not contained within easily mobilisable genetic elements. Thermal processing was seen to be the only secondary processing stage that served as a critical control point for numbers of AMR bacteria. There were significant linkages between some AMR genes in Salmonella. Quaternary ammonium compound (QAC) resistance genes were associated with copper, tetracycline and sulphonamide resistance by virtue of co-location on the same plasmid. No evidence was found that either supported or refuted that there was any association between AMR genes and genes that encoded an altered stress response or enhanced the survival of AMR bacteria exposed to harmful environmental conditions.
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Jones, Scott B., Shmuel P. Friedman, and Gregory Communar. Novel streaming potential and thermal sensor techniques for monitoring water and nutrient fluxes in the vadose zone. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7597910.bard.
Повний текст джерелаАнотація:
The “Novel streaming potential (SP) and thermal sensor techniques for monitoring water and nutrient fluxes in the vadose zone” project ended Oct. 30, 2015, after an extension to complete travel and intellectual exchange of ideas and sensors. A significant component of this project was the development and testing of the Penta-needle Heat Pulse Probe (PHPP) in addition to testing of the streaming potential concept, both aimed at soil water flux determination. The PHPP was successfully completed and shown to provide soil water flux estimates down to 1 cm day⁻¹ with altered heat input and timing as well as use of larger heater needles. The PHPP was developed by Scott B. Jones at Utah State University with a plan to share sensors with Shmulik P. Friedman, the ARO collaborator. Delays in completion of the PHPP resulted in limited testing at USU and a late delivery of sensors (Sept. 2015) to Dr. Friedman. Two key aspects of the subsurface water flux sensor development that delayed the availability of the PHPP sensors were the addition of integrated electrical conductivity measurements (available in February 2015) and resolution of bugs in the microcontroller firmware (problems resolved in April 2015). Furthermore, testing of the streaming potential method with a wide variety of non-polarizable electrodes at both institutions was not successful as a practical measurement tool for water flux due to numerous sources of interference and the M.S. student in Israel terminated his program prematurely for personal reasons. In spite of these challenges, the project funded several undergraduate students building sensors and several master’s students and postdocs participating in theory and sensor development and testing. Four peer-reviewed journal articles have been published or submitted to date and six oral/poster presentations were also delivered by various authors associated with this project. We intend to continue testing the "new generation" PHPP probes at both USU and at the ARO resulting in several additional publications coming from this follow-on research. Furthermore, Jones is presently awaiting word on an internal grant application for commercialization of the PHPP at USU.
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Wei, Fulu, Ce Wang, Xiangxi Tian, Shuo Li, and Jie Shan. Investigation of Durability and Performance of High Friction Surface Treatment. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317281.
Повний текст джерелаАнотація:
The Indiana Department of Transportation (INDOT) completed a total of 25 high friction surface treatment (HFST) projects across the state in 2018. This research study attempted to investigate the durability and performance of HFST in terms of its HFST-pavement system integrity and surface friction performance. Laboratory tests were conducted to determine the physical and mechanical properties of epoxy-bauxite mortar. Field inspections were carried out to identify site conditions and common early HFST distresses. Cyclic loading test and finite element method (FEM) analysis were performed to evaluate the bonding strength between HFST and existing pavement, in particular chip seal with different pretreatments such as vacuum sweeping, shotblasting, and scarification milling. Both surface friction and texture tests were undertaken periodically (generally once every 6 months) to evaluate the surface friction performance of HFST. Crash records over a 5-year period, i.e., 3 years before installation and 2 years after installation, were examined to determine the safety performance of HFST, crash modification factor (CMF) in particular. It was found that HFST epoxy-bauxite mortar has a coefficient of thermal expansion (CTE) significantly higher than those of hot mix asphalt (HMA) mixtures and Portland cement concrete (PCC), and good cracking resistance. The most common early HFST distresses in Indiana are reflective cracking, surface wrinkling, aggregate loss, and delamination. Vacuum sweeping is the optimal method for pretreating existing pavements, chip seal in particular. Chip seal in good condition is structurally capable of providing a sound base for HFST. On two-lane highway curves, HFST is capable of reducing the total vehicle crash by 30%, injury crash by 50%, and wet weather crash by 44%, and providing a CMF of 0.584 in Indiana. Great variability may arise in the results of friction tests on horizontal curves by the use of locked wheel skid tester (LWST) due both to the nature of vehicle dynamics and to the operation of test vehicle. Texture testing, however, is capable of providing continuous texture measurements that can be used to calculate a texture height parameter, i.e., mean profile depth (MPD), not only for evaluating friction performance but also implementing quality control (QC) and quality assurance (QA) plans for HFST.
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Brosh, Arieh, David Robertshaw, Yoav Aharoni, Zvi Holzer, Mario Gutman, and Amichai Arieli. Estimation of Energy Expenditure of Free Living and Growing Domesticated Ruminants by Heart Rate Measurement. United States Department of Agriculture, April 2002. http://dx.doi.org/10.32747/2002.7580685.bard.
Повний текст джерелаАнотація:
Research objectives were: 1) To study the effect of diet energy density, level of exercise, thermal conditions and reproductive state on cardiovascular function as it relates to oxygen (O2) mobilization. 2) To validate the use of heart rate (HR) to predict energy expenditure (EE) of ruminants, by measuring and calculating the energy balance components at different productive and reproductive states. 3) To validate the use of HR to identify changes in the metabolizable energy (ME) and ME intake (MEI) of grazing ruminants. Background: The development of an effective method for the measurement of EE is essential for understanding the management of both grazing and confined feedlot animals. The use of HR as a method of estimating EE in free-ranging large ruminants has been limited by the availability of suitable field monitoring equipment and by the absence of empirical understanding of the relationship between cardiac function and metabolic rate. Recent developments in microelectronics provide a good opportunity to use small HR devices to monitor free-range animals. The estimation of O2 uptake (VO2) of animals from their HR has to be based upon a consistent relationship between HR and VO2. The question as to whether, or to what extent, feeding level, environmental conditions and reproductive state affect such a relationship is still unanswered. Studies on the basic physiology of O2 mobilization (in USA) and field and feedlot-based investigations (in Israel) covered a , variety of conditions in order to investigate the possibilities of using HR to estimate EE. In USA the physiological studies conducted using animals with implanted flow probes, show that: I) although stroke volume decreases during intense exercise, VO2 per one heart beat per kgBW0.75 (O2 Pulse, O2P) actually increases and measurement of EE by HR and constant O2P may underestimate VO2unless the slope of the regression relating to heart rate and VO2 is also determined, 2) alterations in VO2 associated with the level of feeding and the effects of feeding itself have no effect on O2P, 3) both pregnancy and lactation may increase blood volume, especially lactation; but they have no effect on O2P, 4) ambient temperature in the range of 15 to 25°C in the resting animal has no effect on O2P, and 5) severe heat stress, induced by exercise, elevates body temperature to a sufficient extent that 14% of cardiac output may be required to dissipate the heat generated by exercise rather than for O2 transport. However, this is an unusual situation and its affect on EE estimation in a freely grazing animal, especially when heart rate is monitored over several days, is minor. In Israel three experiments were carried out in the hot summer to define changes in O2P attributable to changes in the time of day or In the heat load. The animals used were lambs and young calves in the growing phase and highly yielding dairy cows. In the growing animals the time of day, or the heat load, affected HR and VO2, but had no effect on O2P. On the other hand, the O2P measured in lactating cows was affected by the heat load; this is similar to the finding in the USA study of sheep. Energy balance trials were conducted to compare MEI recovery by the retained energy (RE) and by EE as measured by HR and O2P. The trial hypothesis was that if HR reliably estimated EE, the MEI proportion to (EE+RE) would not be significantly different from 1.0. Beef cows along a year of their reproductive cycle and growing lambs were used. The MEI recoveries of both trials were not significantly different from 1.0, 1.062+0.026 and 0.957+0.024 respectively. The cows' reproductive state did not affect the O2P, which is similar to the finding in the USA study. Pasture ME content and animal variables such as HR, VO2, O2P and EE of cows on grazing and in confinement were measured throughout three years under twenty-nine combinations of herbage quality and cows' reproductive state. In twelve grazing states, individual faecal output (FO) was measured and MEI was calculated. Regression analyses of the EE and RE dependent on MEI were highly significant (P<0.001). The predicted values of EE at zero intake (78 kcal/kgBW0.75), were similar to those estimated by NRC (1984). The EE at maintenance condition of the grazing cows (EE=MEI, 125 kcal/kgBW0.75) which are in the range of 96.1 to 125.5 as presented by NRC (1996 pp 6-7) for beef cows. Average daily HR and EE were significantly increased by lactation, P<0.001 and P<0.02 respectively. Grazing ME significantly increased HR and EE, P<0.001 and P<0.00l respectively. In contradiction to the finding in confined ewes and cows, the O2P of the grazing cows was significantly affected by the combined treatments (P<0.00l ); this effect was significantly related to the diet ME (P<0.00l ) and consequently to the MEI (P<0.03). Grazing significantly increased O2P compared to confinement. So, when EE of grazing animals during a certain season of the year is estimated using the HR method, the O2P must be re measured whenever grazing ME changes. A high correlation (R2>0.96) of group average EE and of HR dependency on MEI was also found in confined cows, which were fed six different diets and in growing lambs on three diets. In conclusion, the studies conducted in USA and in Israel investigated in depth the physiological mechanisms of cardiovascular and O2 mobilization, and went on to investigate a wide variety of ruminant species, ages, reproductive states, diets ME, time of intake and time of day, and compared these variables under grazing and confinement conditions. From these combined studies we can conclude that EE can be determined from HR measurements during several days, multiplied by O2P measured over a short period of time (10-15 min). The study showed that RE could be determined during the growing phase without slaughtering. In the near future the development microelectronic devices will enable wide use of the HR method to determine EE and energy balance. It will open new scopes of physiological and agricultural research with minimizes strain on animals. The method also has a high potential as a tool for herd management.