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Kopchak, Andrii, Anna Romanova i Oleksandr Mykhailenko. "Detection of Titanium Particles in Soft Tissues Adjacent to the Fixators in Patients with Facial Fractures and Bone Defects". Journal of Diagnostics and Treatment of Oral and Maxillofacial Pathology 2, nr 1 (30.03.2018): 25–42. http://dx.doi.org/10.23999/j.dtomp.2018.1.9.
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Background: Open reposition and rigid internal fixation are the main methods of treatment for traumatic injuries of the facial skull and an important stage of bone-plastic, reconstructive, and orthognathic surgery. In contemporary maxillofacial surgery, fixators, implants, and endoprostheses made of titanium or its alloys are widely used due to the high corrosion resistance and biocompatibility. However, recent studies have shown that none of the metal implants used in maxillofacial surgery, orthopedics or traumatology is completely inert. Moreover, they always interact with the surrounding biological environment. Thus, a number of studies have revealed the release of titanium to the adjacent soft tissues. Material and Methods: Titanium fixators (plates and screws) removed in 12 patients in late terms after osteosynthesis, as well as biopsies of the periosteum and fibrous capsule adjacent to the fixation elements made of titanium were investigated. Microscopic fluorescence spectroscopic analysis (M4 TORNADO micro-ray fluorescence spectrometer; Bruker, Bremen, Germany) was used to determine the elemental composition of the removed soft tissue fragments. Scanning electron microscopy (microscope model JSM-6060; JEOL, Japan) was used to study structural changes on the surface of titanium plates and screws. The obtained results were analized with the use of Spirman correlation coefficient, calculated by the IBM SPSS Statistics v.23 software. Results: X-ray fluorescence analysis revealed the inclusion of titanium in all investigated samples with an average content of titanium 48.14% ± 31.1% in metal deposition areas. For samples removed in patients with traumatic facial fractures after metallosteosynthesis, the average content of titanium was 55.6%, and for reconstructive surgeries – 37.72%. The acquired maps of the element deposition showed no topographic inhomogenity of titanium particles distribution. The main distribution patterns were the following: 1) areas of clearly outlined intensive titanium inclusions (90.9-800 μm), and 2) diffuse titanium inclusions which were poorly demarcated. Electronic microscopy of the investigated fixators revealed deformation of the thread, bending of screws, deformation and surface defects of the plates caused by mechanical damage, including microcracks, sharp edges, scratches, dimples.
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Alonso Ruiz, Patricia, i Evgeny Spodarev. "Entropy-based Inhomogeneity Detection in Fiber Materials". Methodology and Computing in Applied Probability 20, nr 4 (27.11.2017): 1223–39. http://dx.doi.org/10.1007/s11009-017-9603-2.
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Xin, Hang, Jingyun Zhang, Cuihong Yang i Yunyun Chen. "Direct Detection of Inhomogeneity in CVD-Grown 2D TMD Materials via K-Means Clustering Raman Analysis". Nanomaterials 12, nr 3 (27.01.2022): 414. http://dx.doi.org/10.3390/nano12030414.
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It is known that complex growth environments often induce inhomogeneity in two-dimensional (2D) materials and significantly restrict their applications. In this paper, we proposed an efficient method to analyze the inhomogeneity of 2D materials by combination of Raman spectroscopy and unsupervised k-means clustering analysis. Taking advantage of k-means analysis, it can provide not only the characteristic Raman spectrum for each cluster but also the cluster spatial maps. It has been demonstrated that inhomogeneities and their spatial distributions are simultaneously revealed in all CVD-grown MoS2, WS2 and WSe2 samples. Uniform p-type doping and varied tensile strain were found in polycrystalline monolayer MoS2 from the grain boundary and edges to the grain center (single crystal). The bilayer MoS2 with AA and AB stacking are shown to have relatively uniform p-doping but a gradual increase of compressive strain from center to the periphery. Irregular distribution of 2LA(M)/E2g1 mode in WS2 and E2g1 mode in WSe2 is revealed due to defect and strain, respectively. All the inhomogeneity could be directly characterized in color-coded Raman imaging with correlated characteristic spectra. Moreover, the influence of strain and doping in the MoS2 can be well decoupled and be spatially verified by correlating with the clustered maps. Our k-means clustering Raman analysis can dramatically simplify the inhomogeneity analysis for large Raman data in 2D materials, paving the way towards direct evaluation for high quality 2D materials.
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Netzelmann, U., J. Pelzl, D. Fournier i A. C. Boccara. "Nondestructive evaluation of magnetic materials by ferromagnetic-resonance photothermal-deflection spectroscopy". Canadian Journal of Physics 64, nr 9 (1.09.1986): 1307–10. http://dx.doi.org/10.1139/p86-228.
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Detection of ferromagnetic resonance (FMR) by photothermal beam deflection has been used to study the spatial inhomogeneity of magnetic properties. The technique has been applied to measure the depth dependence of FMR in layered recorder tapes and to determine the lateral variation of the demagnetizing field in metal–glass ribbons.
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Chady, Tomasz, i Ryszard Łukaszuk. "Examining Ferromagnetic Materials Subjected to a Static Stress Load Using the Magnetic Method". Materials 14, nr 13 (22.06.2021): 3455. http://dx.doi.org/10.3390/ma14133455.
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This paper discusses the experimental examination of anisotropic steel-made samples subjected to a static stress load. A nondestructive testing (NDT) measurement system with a transducer, which enables observation of local hysteresis loops and detection of samples’ inhomogeneity, is proposed. Local hysteresis loops are measured on two perpendicular axes, including one parallel to the rolling direction of the samples. The results confirm that the selected features of the local hysteresis loops provide important information about the conditions of ferromagnetic materials. Furthermore, it is shown that the selected parameters of the statistical analysis of the achieved measurements are beneficial for evaluating stress and fatigue changes induced in the material.
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Xiao, Ling, Zhuguan Liang, Yawen Li, Jian Wang, Kailin Zhou, Ping Li, Xiaohua Xu, E. I. Rau i Wenguo Hu. "In SEM a New Method of Internal Micrographic Visualization of Semiconductor Materials and IC by Crossing the Surface". Microscopy and Microanalysis 7, S2 (sierpień 2001): 484–85. http://dx.doi.org/10.1017/s143192760002849x.
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In the paper, we firstly publish a new method of internal micrographic visualization of semiconductor and IC. The quality and reliability of the semiconductor materials (SM) and the integrated circuits (IC) have always been concerned Having a high resolution, high reliable and nondestructive detection method is the key element for their improvements.Silicon oxide layers are used to provide the electrical insulation in the multi-structured ICs. The IC device surfaces are often protected by silicon oxide and silicon nitride layers. Therefore, these insulation layers also cover any inhomogeneity and defect located within the IC devices. It is necessary to have an examining method to detect those defects that are under the insulation layers without damaging the samples. However, the conventional scanning electron microscope (SEM) cannot be utilized to image and examine the surfaces that are positioned below the insulation layers.Novel nondestructive and contactless method has been developed in our laboratory to obtain the internal micrograph that crosses the surface of the semiconductor material and the integrated circuit.
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Rolland, J. P., i H. H. Barrett. "Effect of random background inhomogeneity on observer detection performance". Journal of the Optical Society of America A 9, nr 5 (1.05.1992): 649. http://dx.doi.org/10.1364/josaa.9.000649.
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Chandra, Vedant, Hsiang-Chih Hwang, Nadia L. Zakamska, Simon Blouin, Andrew Swan, Thomas R. Marsh, Ken J. Shen i in. "The SN Ia runaway LP 398-9: detection of circumstellar material and surface rotation". Monthly Notices of the Royal Astronomical Society 512, nr 4 (13.04.2022): 6122–33. http://dx.doi.org/10.1093/mnras/stac883.
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ABSTRACT A promising progenitor scenario for Type Ia supernovae (SNeIa) is the thermonuclear detonation of a white dwarf in a close binary system with another white dwarf. After the primary star explodes, the surviving donor can be spontaneously released as a hypervelocity runaway. One such runaway donor candidate is LP 398-9, whose orbital trajectory traces back ≈105 yr to a known supernova remnant. Here, we report the discovery of carbon-rich circumstellar material around LP 398-9, revealed by a strong infrared excess and analysed with follow-up spectroscopy. The circumstellar material is most plausibly composed of inflated layers from the star itself, mechanically and radioactively heated by the past companion’s supernova. We also detect a 15.4 h periodic signal in the UV and optical light curves of LP 398-9, which we interpret as surface rotation. The rotation rate is consistent with theoretical predictions from this supernova mechanism, and the brightness variations could originate from surface inhomogeneity deposited by the supernova itself. Our observations strengthen the case for this double-degenerate SNIa progenitor channel, and motivate the search for more runaway SNIa donors.
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Pochtar’, A. A., I. G. Vasil’eva i V. V. Malakhov. "Detecting spatial inhomogeneity manifestations in the chemical composition of functional materials by stoichiographic methods". Journal of Structural Chemistry 55, nr 6 (listopad 2014): 1160–65. http://dx.doi.org/10.1134/s0022476614060262.
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Chen, Kai, Libing Bai, Yifan Chen, Yuhua Cheng, Shulin Tian i Peipei Zhu. "Defect Automatic Identification of Eddy Current Pulsed Thermography". Journal of Sensors 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/326316.
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Eddy current pulsed thermography (ECPT) is an effective nondestructive testing and evaluation (NDT&E) technique, and has been applied for a wide range of conductive materials. Manual selected frames have been used for defects detection and quantification. Defects are indicated by high/low temperature in the frames. However, the variation of surface emissivity sometimes introduces illusory temperature inhomogeneity and results in false alarm. To improve the probability of detection, this paper proposes a two-heat balance states-based method which can restrain the influence of the emissivity. In addition, the independent component analysis (ICA) is also applied to automatically identify defect patterns and quantify the defects. An experiment was carried out to validate the proposed methods.
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Garshelis, Ivan J., i Guillaume Crevecoeur. "Nondestructive Detection of Inhomogeneity in the Magnetic Properties of Materials With a Moving Magnet Hysteresis Comparator". IEEE Transactions on Magnetics 48, nr 11 (listopad 2012): 4409–12. http://dx.doi.org/10.1109/tmag.2012.2201458.
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Demirli, Ramazan, Moeness G. Amin, Xizhong Shen i Yimin D. Zhang. "Ultrasonic Flaw Detection and Imaging through Reverberant Layers via Subspace Analysis and Projection". Advances in Acoustics and Vibration 2012 (18.07.2012): 1–10. http://dx.doi.org/10.1155/2012/957379.
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Ultrasonic flaw detection and imaging through reverberant layers are challenging problems owing to the layer-induced reverberations and front surface reflections. These undesired signals present a strong clutter and mask the flaw echoes. In this paper, a subspace-based approach is developed for removing, or significantly reducing, the unwanted reverberations, enabling proper flaw detection and imaging. The technique utilizes a set of independent clutter-only reference measurements of the material through the layer. If these measurements are not available, array measurements of the material with flaws are used instead. The clutter, due to its high strength relative to the flaw reflections, forms a subspace spanned by the eigenvectors corresponding to the dominant eigenvalues of the data covariance matrix. The clutter subspace is estimated and removed using orthogonal subspace projection. The clutter usually occupies multidimension subspace that is dependent on the level of coupling, material inhomogeneity, surface roughness, and the sampling rate of the measurements. When the clutter-only reference is not available, information theoretic techniques are used to estimate the dimension of the clutter subspace so that clutter signals are sufficiently suppressed without distorting the flaw signals. The effectiveness of the proposed approach is demonstrated using simulations and real measurement results.
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Da, Wei, Peng-wei Wang, Yi-fu Wang, Ming-fei Li i Liang Yang. "Inhomogeneity of Free Volumes in Metallic Glasses under Tension". Materials 12, nr 1 (29.12.2018): 98. http://dx.doi.org/10.3390/ma12010098.
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In this work, the deformation of Zr2Cu metallic glass (MG) under uniaxial tensile stress was investigated at the atomic level using a series of synchrotron radiation techniques combined with molecular dynamics simulation. A new approach to the quantitative detection of free volumes in MGs was designed and it was found that free volumes increase in the elastic stage, slowly expand in the yield stage, and finally reach saturation in the plastic stage. In addition, in different regions of the MG model, free volumes exhibited inhomogeneity under stress, in terms of size, density, and distribution. In particular, the expansion of free volumes in the center region was much more rapid than those in the other regions. It is interesting that the density of free volumes in the center region abnormally decreased with strain. It was revealed that the atomic-level stress between different regions may contribute to the inhomogeneity of free volumes under stress. In addition, the inhomogeneous change of free volumes during the deformation was confirmed by the evolution of local atomic shear strains in different regions. The present work provides in-depth insight into the deformation mechanisms of MGs.
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Prager, Jens, Christian Höhne i Mehbub Ur Rahman. "Synthetic Aperture Focusing Technique for Detecting Transverse Cracks in Austenitic and Dissimilar Welds". Key Engineering Materials 569-570 (lipiec 2013): 1036–43. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.1036.
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The inspection of austenitic and dissimilar welds using ultrasound demands for sophisticated testing techniques. The application of reconstruction methods like the Synthetic Aperture Focusing Technique (SAFT) on the measurement results provides an appropriate approach for defect characterization and sizing. Nevertheless, the reconstruction algorithm has to consider the aniso-tropic wave propagation inside the inhomogeneous weld material. In recent years the detection of transverse cracks has become increasingly important for ensuring the structural integrity of pipes in the primary circuit of nuclear power plants or longitudinally welded, cladded pipes. However, relia-ble inspection techniques are hardly available. In this particular case, it is expected that the compar-atively long propagation path of the ultrasonic wave field inside the inhomogeneous weld material enhances the effect of anisotropy and influences the accuracy and the signal-to-noise-ratio of the reconstruction result. In this contribution we suggest an advanced ultrasonic testing technique for detecting and sizing of transversal cracks in austenitic and dissimilar welds. The method applies a SAFT reconstruction algorithm considering the anisotropy and the inhomogeneity. A V-arrangement of the transducers in pitch-catch technique is chosen to avoid a direct coupling on the weld face. The reconstruction algo-rithm is based on an extended 3-dimensional weld model and uses a ray-tracing approach for de-termining the wave propagation paths. Along with the reconstruction algorithm the transducer set-up and experimental results of different specimens with artificial transverse flaws are presented. The availability of the proposed method for crack sizing is assessed in comparison to conventional testing techniques.
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Ying-Heng Yeo i Kin-Sam Yen. "Impurities Detection in Intensity Inhomogeneous Edible Bird’s Nest (EBN) Using a U-Net Deep Learning Model". International Journal of Engineering and Technology Innovation 11, nr 2 (1.04.2021): 135–45. http://dx.doi.org/10.46604/ijeti.2021.6891.
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As an important export, cleanliness control on edible bird’s nest (EBN) is paramount. Automatic impurities detection is in urgent need to replace manual practices. However, effective impurities detection algorithm is yet to be developed due to the unresolved inhomogeneous optical properties of EBN. The objective of this work is to develop a novel U-net based algorithm for accurate impurities detection. The algorithm leveraged the convolution mechanisms of U-net for precise and localized features extraction. Output probability tensors were then generated from the deconvolution layers for impurities detection and positioning. The U-net based algorithm outperformed previous image processing-based methods with a higher impurities detection rate of 96.69% and a lower misclassification rate of 10.08%. The applicability of the algorithm was further confirmed with a reasonably high dice coefficient of more than 0.8. In conclusion, the developed U-net based algorithm successfully mitigated intensity inhomogeneity in EBN and improved the impurities detection rate.
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Tan, Ryan, Jessica Charest, Bogdan Dryzhakov, Chris Busch, Lance Drouet, Bin Hu, Mahshid Ahmadi i Eric Lukosi. "Characterization of solution grown 3D polycrystalline methylammonium lead tribromide for x-ray detection". Journal of Applied Physics 132, nr 20 (28.11.2022): 204503. http://dx.doi.org/10.1063/5.0100362.
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Solution grown metal halide perovskites (MHPs) are a class of low-cost, direct conversion semiconducting materials with the potential to meet the need for large areas, high stopping power, and high sensitivity x-ray detectors. While polycrystalline MHP thin films have shown significant potential for meeting this need, their efficiencies for detecting x rays are limited by their thickness. This article presents an MHP variant, methylammonium lead tribromide (MAPB) in the form of 3D polycrystalline mosaic wafers with relatively high hole transport properties that demonstrated stable sensitivity during irradiation. An expedited and efficient detector fabrication method that did not include polishing or sintering was evaluated, and a radiograph of a brass key was produced using electron collection from the resulting wafer. However, a high dose rate was required due to very low sensitivity values. The effects of surface inhomogeneity and radiation damage were investigated as explanatory factors, and these phenomena were further characterized through IV measurements, current response as a function of electric field and x-ray dose rate, and alpha particle irradiation. The results indicated that although compromising surface quality for fabrication efficiency was the primary hindrance to the x-ray detection performance of 3D polycrystalline MAPB, stable performance could still be achieved under reasonable dose rates.
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Zhao, Yan, Franz B. Spingler, Yatish Patel, Gregory J. Offer i Andreas Jossen. "Localized Swelling Inhomogeneity Detection in Lithium Ion Cells Using Multi-Dimensional Laser Scanning". Journal of The Electrochemical Society 166, nr 2 (2019): A27—A34. http://dx.doi.org/10.1149/2.0011902jes.
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Teti, Roberto, Tiziana Segreto, Alessandra Caggiano i Luigi Nele. "Smart Multi-Sensor Monitoring in Drilling of CFRP/CFRP Composite Material Stacks for Aerospace Assembly Applications". Applied Sciences 10, nr 3 (21.01.2020): 758. http://dx.doi.org/10.3390/app10030758.
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Composite material parts are typically laid out in near-net-shape, i.e., very close to the finished product configuration. However, further machining processes are often required to meet dimensional and tolerance requirements. Drilling, edge trimming and slotting are the main cutting processes employed for carbon fiber-reinforced plastic (CFRP) composite materials. In particular, drilling stands out as the most widespread machining process of CFRP composite parts, chiefly in the aerospace industrial sector, due to the extensive use of mechanical joints, such as rivets, rather than welded or bonded joints. However, CFRP drilling is markedly challenging: due to CFRP abrasiveness, inhomogeneity and anisotropic properties, tool wear rates are inherently high leading to superior cutting forces and detrimental effects on workpiece surface quality and material integrity. Damage such as delamination, cracks or matrix thermal degradation is often observed as the result of uncontrolled tool wear or improper machining conditions. Sensor monitoring of drilling operations is, therefore, highly desirable for process conditions’ optimization and tool life maximization. The development of this kind of automated control technologies for process and tool state evaluation can notably contribute to the reduction of scraps and tool costs as well as to the improvement of process productivity in the drilling of CFRP composite material parts. In this paper, multi-sensor process monitoring based on thrust force and torque signal detection and analysis was applied during drilling of CFRP/CFRP laminate stacks for the assembly of aircraft fuselage panels with the scope to evaluate the tool wear state. Different signal-processing methods were utilised to extract diverse types of features from the detected sensor signals. A machine-learning approach based on an artificial neural network (ANN) was implemented to make smart decisions on the timely execution of tool change, which is highly functional for CFRP drilling process automation.
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Zheng, Jia, Chuan Tang, Yuanxi Sun, Mingchi Feng i Congzhe Wang. "An Enhanced U-Net Approach for Segmentation of Aeroengine Hollow Turbine Blade". Mathematics 10, nr 22 (12.11.2022): 4230. http://dx.doi.org/10.3390/math10224230.
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The hollow turbine blade plays an important role in the propulsion of the aeroengine. However, due to its complex hollow structure and nickel-based superalloys material property, only industrial computed tomography (ICT) could realize its nondestructive detection with sufficient intuitiveness. The ICT detection precision mainly depends on the segmentation accuracy of target ICT images. However, because the hollow turbine blade is made of special superalloys and contains many small unique structures such as film cooling holes, exhaust edges, etc., the ICT image quality of the hollow turbine blades is often deficient, with artifacts, low contrast, and inhomogeneity scattered around the blade contour, making it hard for traditional mathematical model-based methods to acquire satisfying segmentation precision. Therefore, this paper presents a deep learning-based approach, i.e., the enhanced U-net with multiscale inputs, dense blocks, focal loss function, and residual path in the skip connection to realize the high-precision segmentation of the hollow turbine blade. The experimental results show that our proposed enhanced U-net can achieve better segmentation accuracy for practical turbine blades than conventional U-net and traditional mathematical model-based methods.
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Kopnov, Gregory, Sudhansu Sekhar Das i Alexander Gerber. "Effect of Fractal Topology on the Resistivity Response of Thin Film Sensors". Sensors 23, nr 5 (22.02.2023): 2409. http://dx.doi.org/10.3390/s23052409.
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We discuss the effect of topological inhomogeneity of very thin metallic conductometric sensors on their response to external stimuli, such as pressure, intercalation, or gas absorption, that modify the material’s bulk conductivity. The classical percolation model was extended to the case in which several independent scattering mechanisms contribute to resistivity. The magnitude of each scattering term was predicted to grow with the total resistivity and diverge at the percolation threshold. We tested the model experimentally using thin films of hydrogenated palladium and CoPd alloys where absorbed hydrogen atoms occupying the interstitial lattice sites enhance the electron scattering. The hydrogen scattering resistivity was found to grow linearly with the total resistivity in the fractal topology range in agreement with the model. Enhancement of the absolute magnitude of the resistivity response in the fractal range thin film sensors can be particularly useful when the respective bulk material response is too small for reliable detection.
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Grasso, Marco. "In Situ Monitoring of Powder Bed Fusion Homogeneity in Electron Beam Melting". Materials 14, nr 22 (19.11.2021): 7015. http://dx.doi.org/10.3390/ma14227015.
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Increasing attention has been devoted in recent years to in situ sensing and monitoring of the electron beam melting process, ranging from seminal methods based on infrared imaging to novel methods based on backscattered electron detection. However, the range of available in situ monitoring capabilities and solutions is still quite limited compared to the wide number of studies and industrial toolkits in laser-based additive manufacturing processes. Some methods that are already industrially available in laser powder bed fusion systems, such as in situ detection of recoating errors, have not yet been investigated and tested in electron beam melting. Motivated by the attempt to fill this gap, we present a novel in situ monitoring methodology that can be easily implemented in industrial electron beam melting machines. The method is aimed at identifying local inhomogeneity and irregularities in the powder bed by means of layerwise image acquisition and processing, with no external illumination source apart from the light emitted by the hot material underneath the currently recoated layer. The results show that the proposed approach is suitable to detect powder bed anomalies, while also highlighting the link between the severity of in situ detected errors and the severity of resulting defects in the additively manufactured part.
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Li, Ruihua, Hao Li i Bo Hu. "Damage Identification of Large Generator Stator Insulation Based on PZT Sensor Systems and Hybrid Features of Lamb Waves". Sensors 18, nr 9 (21.08.2018): 2745. http://dx.doi.org/10.3390/s18092745.
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Large generators are the principal pieces of equipment in power systems, and their operation reliability critically depends on the stator insulation. Damages in stator insulation will gradually lead to the failure and breakdown of generator. Due to the advantages of Lamb waves in Structural health monitoring (SHM), in this study, a distributed piezoelectric (PZT) sensor system and hybrid features of the Lamb waves are introduced to identify stator insulation damage of large generator. A hierarchical probability damage-imaging (PDI) algorithm is proposed to tackle the material inhomogeneity and anisotropy of the stator insulation. The proposed method includes three steps: global detection using correlation coefficients, local detection using Time of flight (ToF) along with the amplitude of damage-scattered Lamb wave, and final images fusion. Wavelet Transform was used to extract the ToF of Lamb wave in terms of the time-frequency domain. Finite Element Modeling (FEM) simulation and experimental work were carried out to identify four typical stator insulation damages for validation, including inner void, inner delamination, puncture, and crack. Results show that the proposed method can precisely identify the location of stator insulation damage, and the reconstruction image can be used to identify the size of stator insulation damage.
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Chen, Yulei, Tongtong Li, Guoqiang Chai, Dawei Wang, Bin Lu, Aixin Guo i Jin Tian. "Enhancing Spin-Based Sensor Sensitivity by Avoiding Microwave Field Inhomogeneity of NV Defect Ensemble". Nanomaterials 12, nr 22 (8.11.2022): 3938. http://dx.doi.org/10.3390/nano12223938.
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The behavior of the magnetic field sensitivity of nitrogen-vacancy (NV) centers as a function of microwave power and the inhomogeneous distribution of MW fields was systematically studied. An optimal structure for exciting spin structures by MW signals was designed using two parallel loop antennas. The volume of the homogeneous regions was approximately 42 mm3, and the associated diameter of the diamond reached up to 5.2 mm with 1016 NV sensors. Based on this structure, the detection contrast and voltage fluctuation of an optically detected magnetic resonance (ODMR) signal were optimized, and the sensitivity was improved to 5 nT/√Hz. In addition, a pulse sequence was presented to fully eliminate the MW broadening. The magnetic field sensitivity was improved by approximately one order of magnitude as the π-pulse duration was increased to its coherence time. This offers a useful way to improve the sensitivity of spin-based sensors.
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Ley, Sebastian, Jürgen Sachs, Bernd Faenger, Ingrid Hilger i Marko Helbig. "MNP-Enhanced Microwave Medical Imaging by Means of Pseudo-Noise Sensing". Sensors 21, nr 19 (4.10.2021): 6613. http://dx.doi.org/10.3390/s21196613.
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Magnetic nanoparticles have been investigated for microwave imaging over the last decade. The use of functionalized magnetic nanoparticles, which are able to accumulate selectively within tumorous tissue, can increase the diagnostic reliability. This paper deals with the detecting and imaging of magnetic nanoparticles by means of ultra-wideband microwave sensing via pseudo-noise technology. The investigations were based on phantom measurements. In the first experiment, we analyzed the detectability of magnetic nanoparticles depending on the magnetic field intensity of the polarizing magnetic field, as well as the viscosity of the target and the surrounding medium in which the particles were embedded, respectively. The results show a nonlinear behavior of the magnetic nanoparticle response depending on the magnetic field intensity for magnetic nanoparticles diluted in distilled water and for magnetic nanoparticles embedded in a solid medium. Furthermore, the maximum amplitude of the magnetic nanoparticles responses varies for the different surrounding materials of the magnetic nanoparticles. In the second experiment, we investigated the influence of the target position on the three-dimensional imaging of the magnetic nanoparticles in a realistic measurement setup for breast cancer imaging. The results show that the magnetic nanoparticles can be detected successfully. However, the intensity of the particles in the image depends on its position due to the path-dependent attenuation, the inhomogeneous microwave illumination of the breast, and the inhomogeneity of the magnetic field. Regarding the last point, we present an approach to compensate for the inhomogeneity of the magnetic field by computing a position-dependent correction factor based on the measured magnetic field intensity and the magnetic susceptibility of the magnetic particles. Moreover, the results indicate an influence of the polarizing magnetic field on the measured ultra-wideband signals even without magnetic nanoparticles. Such a disturbing influence of the polarizing magnetic field on the measurements should be reduced for a robust magnetic nanoparticles detection. Therefore, we analyzed the two-state (ON/OFF) and the sinusoidal modulation of the external magnetic field concerning the detectability of the magnetic nanoparticles with respect to these spurious effects, as well as their practical application.
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Steinbild, P. J., N. Wieja, J. Condé-Wolter, A. Winkler, T. Ehrig, P. Kostka i N. Modler. "Changes in electric resistance of cracked copper-coated, pitch-based carbon fibres for structural health monitoring in a glider wing". Journal of Physics: Conference Series 2526, nr 1 (1.06.2023): 012066. http://dx.doi.org/10.1088/1742-6596/2526/1/012066.
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Abstract Structural health monitoring based on detecting strain enables further exploitation of the lightweight potential of aircraft structures. Since carbon fibres (CF) can be easily integrated into aircraft structures made of fibre-reinforced plastics (FRP), their use in sensor applications has become subject of research. One of many novel approaches is the use of cracked CF for strain detection. During loading and unloading, the fibre cracks are opening and closing respectively, resulting in substantial changes in the electric resistance of the CF. The high dependence of the electric resistance on the mechanical strain enables spatially resolved strain sensing along the CF based on the electric time domain reflectometry (ETDR) principle. However, due to high inhomogeneity of the used pitch-based CF and the resulting electric properties, the ETDR-signal is degraded largely by impedance mismatch along the transmission line, which limits the measuring length of a spatially resolved sensor. In this contribution, a concept for a spatially resolved CF-based strain sensor is described, outlining the challenges that need to be addressed. One approach for the extension of the measuring length is lowering the base resistivity of the used CF, which is discussed in detail. In order to achieve a low base resistivity while maintaining the characteristic of opening and closing fibre cracks, copper-coated CF are investigated. The copper-coated pitch-based CF are integrated into test specimens consisting of a composite material and are subjected to tensile loading. Simultaneously to the deflection, the electrical resistance is measured. Consequently, the sensitivity to strain of the CF is determined and discussed.
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Vértesy, Gábor, Antal Gasparics i Ildikó Szenthe. "Investigation of Potential Material Inhomogeneity in the Magnetically Detected Neutron-Irradiation-Generated Structural Degradation of Nuclear Reactor Pressure Vessel Steel". Applied Sciences 12, nr 22 (16.11.2022): 11640. http://dx.doi.org/10.3390/app122211640.
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A novel nondestructive method called magnetic adaptive testing has been previously applied to detect the neutron-irradiation-generated structural changes in reactor pressure vessel steel material. This method has been found to be a useful tool for this purpose, and good correlation—as a tendency—has been found between the estimated ductile-to-brittle transition temperature and magnetic parameters. However, a significant scattering of measured points was also observed for the investigated set of Charpy specimens. The main result of the work was that by magnetic selection of samples, the scatter can be notably reduced. As a conclusion, the magnetically measured parameters seemed to be precise and reliable for the detection of embrittlement of the reactor pressure vessel steel, with lower scattering of points than in the conventionally used destructive mechanical characteristics (ductile-to-brittle transition temperature). This result is surprising and needs further verification. The purpose of the present work is to repeat the measurement on irradiated reactor steel blocks. In this work, instead of the DBTT transition temperature, individually measured Vickers hardness (VH) data were used to help characterize the mechanical properties of the material. The so-called “property transformation” is a known and applied technique in the nuclear industry. The mechanical property characterized by the transition temperature cannot be determined individually for each specimen; instead, it can be obtained only on a set of samples by statistical fitting. Therefore, the individually measured Vickers hardness values can be utilized in order to predict the individual transition temperature values by the help of the property transformation technique. In this paper, however, not these derived transition temperature values, but their origins, the Vickers hardness values, are studied in a direct manner. The same behavior of blocks was observed as in the case of Charpy specimens, which is considered to validate the previously published results. As a possible reason for the scattering of points, large magnetic inhomogeneity of samples cut even from the same block was also proved. The magnetic parameters and Vickers hardness correlate well with each other. This result justifies the potential future application of magnetic techniques in practice aimed at the regular inspection of nuclear reactors.
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Kim, Jun Sung, Sang-Kyu Park i Haeshin Lee. "Sniffer worm, C. elegans, as a toxicity evaluation model organism with sensing and locomotion abilities". PLOS ONE 18, nr 8 (2.08.2023): e0289493. http://dx.doi.org/10.1371/journal.pone.0289493.
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Additive manufacturing, or 3D printing, has revolutionized the way we create objects. However, its layer-by-layer process may lead to an increased incidence of local defects compared to traditional casting-based methods. Factors such as light intensity, depth of light penetration, component inhomogeneity, and fluctuations in nozzle temperature all contribute to defect formations. These defective regions can become sources of toxic component leakage, but pinpointing their locations in 3D printed materials remains a challenge. Traditional toxicological assessments rely on the extraction and subsequent exposure of living organisms to these harmful agents, thus only offering a passive detection approach. Therefore, the development of an active system to both identify and locate sources of toxicity is essential in the realm of 3D printing technologies. Herein, we introduce the use of the nematode model organism, Caenorhabditis elegans (C. elegans), for toxicity evaluation. C. elegans exhibits distinctive ’sensing’ and ’locomotion’ capabilities that enable it to actively navigate toward safe zones while steering clear of hazardous areas. This active behavior sets C. elegans apart from other aquatic and animal models, making it an exceptional choice for immediate and precise identification and localization of toxicity sources in 3D printed materials.
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Mikuła, Edyta, i Kamila Malecka-Baturo. "An Overview of the Latest Developments in the Electrochemical Aptasensing of Neurodegenerative Diseases". Coatings 13, nr 2 (19.01.2023): 235. http://dx.doi.org/10.3390/coatings13020235.
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Neurodegenerative diseases (NDs) are becoming a major global health problem. They constitute an incurable diverse group of disorders characterized by the progressive degeneration of the structure and function of the central or peripheral nervous system. There is an enormous unmet demand worldwide for methods for the early detection of ND biomarkers. The complexity of the molecular mechanisms underlying neuronal degeneration as well as the inhomogeneity of the patient population pose a great challenge for the development of early diagnostic tools. Various analytical technologies have been developed to meet this challenge. Among the various approaches reported so far, biosensors are powerful analytical implements that have been applied to detect biomarkers of NDs. Over the past decade, electrochemical aptasensors have been at the forefront of this development not only thanks to their low cost and simple design but also due to advances in nanomaterials modifying the surface of the transducers involved. The design of electrochemical aptasensors for the detection of ND biomarkers such as α-synuclein, amyloid β peptide, tau protein and human cellular prion protein were summarized and compared. Innovative strategies for increasing their sensitivity and selectivity were also pointed out. Undoubtedly, there is still a need for low-cost, fast and easy-to-use systems for the early detection of NDs.
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Bosse, Stefan, Dennis Weiss i Daniel Schmidt. "Supervised Distributed Multi-Instance and Unsupervised Single-Instance Autoencoder Machine Learning for Damage Diagnostics with High-Dimensional Data—A Hybrid Approach and Comparison Study". Computers 10, nr 3 (18.03.2021): 34. http://dx.doi.org/10.3390/computers10030034.
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Structural health monitoring (SHM) is a promising technique for in-service inspection of technical structures in a broad field of applications in order to reduce maintenance efforts as well as the overall structural weight. SHM is basically an inverse problem deriving physical properties such as damages or material inhomogeneity (target features) from sensor data. Often models defining the relationship between predictable features and sensors are required but not available. The main objective of this work is the investigation of model-free distributed machine learning (DML) for damage diagnostics under resource and failure constraints by using multi-instance ensemble and model fusion strategies and featuring improved scaling and stability compared with centralised single-instance approaches. The diagnostic system delivers two features: A binary damage classification (damaged or non-damaged) and an estimation of the spatial damage position in case of a damaged structure. The proposed damage diagnostics architecture should be able to be used in low-resource sensor networks with soft real-time capabilities. Two different machine learning methodologies and architectures are evaluated and compared posing low- and high-resolution sensor processing for low- and high-resolution damage diagnostics, i.e., a dedicated supervised trained low-resource and an unsupervised trained high-resource deep learning approach, respectively. In both architectures state-based recurrent artificial neural networks are used that process spatially and time-resolved sensor data from experimental ultrasonic guided wave measurements of a hybrid material (carbon fibre laminate) plate with pseudo defects. Finally, both architectures can be fused to a hybrid architecture with improved damage detection accuracy and reliability. An extensive evaluation of the damage prediction by both systems shows high reliability and accuracy of damage detection and localisation, even by the distributed multi-instance architecture with a resolution in the order of the sensor distance.
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Bache, Martin R., Christopher D. Newton, John Paul Jones, Stephen Pattison, Louise Gale, Pascual Ian Nicholson i Eleri Weston. "Advances in Damage Monitoring Techniques for the Detection of Failure in SiCf/SiC Ceramic Matrix Composites". Ceramics 2, nr 2 (15.05.2019): 347–71. http://dx.doi.org/10.3390/ceramics2020028.
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From a disruptive perspective, silicon carbide (SiC)-based ceramic matrix composites (CMCs) provide a considerable temperature and weight advantage over existing material systems and are increasingly finding application in aerospace, power generation and high-end automotive industries. The complex structural architecture and inherent processing artefacts within CMCs combine to induce inhomogeneous deformation and damage prior to ultimate failure. Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in CMCs. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. This is important if CMCs are to be utilised to their full potential within industrial applications. Bulk measurements of strain via extensometry or even localised strain gauging would fail to characterise the ensuing inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research has, therefore, applied digital image correlation (DIC), electrical resistance monitoring and acoustic emission techniques to the room and high-temperature assessment of ceramic matrix composites under axial tensile and fatigue loading, with particular attention afforded to a silicon carbide fibre-reinforced silicon carbide composite (SiCf/SiC) variant. Data from these separate monitoring techniques plus ancillary use of X-ray computed tomography, in-situ scanning electron microscopy and optical inspection were correlated to monitor the onset and progression of damage during mechanical loading. The benefits of employing a concurrent, multi-technique approach to monitoring damage in CMCs are demonstrated.
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Rabbi, MS, i K. Teramoto. "A0-Mode Lamb Wave Based Detection of Corrosion under Coating Film in Plate-Like Metallic Structures: Analytical, Finite Element and Experimental Studies". GUB Journal of Science and Engineering 5, nr 1 (28.06.2018): 37–44. http://dx.doi.org/10.3329/gubjse.v5i1.47899.
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The fundamental order antisymmetric mode (A0-mode) Lamb wave based a quantitative acoustical imaging technique is proposed in this paper to classify the corroded region under coating film within the metallic structure. This method estimates versatility qualities of the zone of intrigue to some degree inhomogeneity differentiated to the encompassed materials. However, a converging region consisting of incident wave field and scattered wave field difficult to demonstrate from the observed signals. The proposed method focuses on reconstructing the image of the defect by calculating the shear strains. The shear strains deduced from the observed normal displacement of the specimen. A covariance matrix has been constructed using the shear strains and meaningful determinant values of the matrix reveal the overlapping region. As the beginning overlapping region developed at the edge of the defect, thus image of the defect can be reconstructed by this technique. This paper discussed the analytical approach of computing the incoming, outgoing, as well as the transmitting wave fields. Physical interpretation of the analytical prediction is explored via numerical simulations and acoustical observations.
GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 5(1), Dec 2018 P 37-44
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Zumr, David, Václav David, Josef Krása i Jiří Nedvěd. "Geophysical Evaluation of the Inner Structure of a Historical Earth-Filled Dam". Proceedings 2, nr 11 (3.08.2018): 664. http://dx.doi.org/10.3390/proceedings2110664.
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Small earth dams usually lack the detailed seepage monitoring system that would provide high resolution data on changes in seepage flow. Alternative solution is monitoring of the temperature and electrical resistivity in the body of the dams. Geophysical methods are useful techniques for a non-destructive exploration of the subsurface. We have utilized the combination of electrical resistivity tomography (ERT), ground penetrating radar (GPR) and multi-depth electromagnetical conductivity meter (CMD) techniques to observe the inner structure, especially internal failures, of the historical earth-filled dams. Longitudinal and transversal profiles of four typical fishpond dams in the Czech Republic were measured within this research. The dams were constructed as early as in the 15th century, some of them went through minor reconstruction. The aim of the application of geophysical methods for investigation of old fishpond dams was to detect and localize the boundary of the dam foundation, new earth material from the reconstruction works, cone of water depression, technical objects location, potential internal erosion, cavities, inhomogeneity in the water content pattern and any other anomalies. The primary results show that the ERT is suitable to observe the dam stratification, dam foundation, bedrock below the dam and large anomalies. GPR is suitable for small objects and anomalies detection in the shallow depths.
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Apostolopoulos, G., C. Pavlaki, V. Perleros i G. Amolochitis. "Geophysical investigation and its geological interpretation in the frame of an intergrated survey prior to a dam construction in Plati River Valley, Rethymno, Greece." Bulletin of the Geological Society of Greece 47, nr 3 (21.12.2016): 1052. http://dx.doi.org/10.12681/bgsg.10948.
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A geophysical survey using electrical resistivity tomography (ERT) method(25 ERT profiles of 240m total length and 2 ERT profiles of 1000m total length) in the area of Plati River valley gave valuable information regarding the stratigraphy, related to loose sediments, various faces of flysch and limestone, the tectonic status and the detection of areas of thick and extensive sheared siltstone, that geoelectrically is similar to clay,material useful for the core of the future dam. Both branches of river and valley and in greater detail the area near the position of the dam have detected showing the underground in a 2D and 3D manner. The thickness of neogene andflysch exceeds 40m. Alternations of siltstones-sandstones are met in flysch and in places cohesive sandstones are also met without continuation in an extended area. The siltstonelayers due to their shear character present clayey characteristics in respect of their resistivities. In general zones of limestone uplift have not been detected, which may create problems of leakages apart of the dam area where lateral inhomogeneity between flysch and limestone has been detected (probable fault). The various limestone bodies met in flysch or neogene do not have continuation in depth and they are isolated.
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Wang, Yinshun, Yan Lu, Xi Xu, Shaotao Dai, Dong Hui, Liye Xiao i Liangzhen Lin. "Detecting and describing the inhomogeneity of critical current in practical long HTS tapes using contact-free method". Cryogenics 47, nr 4 (kwiecień 2007): 225–31. http://dx.doi.org/10.1016/j.cryogenics.2007.01.006.
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Castel, Vincent, Jamal Ben Youssef i Christian Brosseau. "Broadband Ferromagnetic Resonance Measurements in Ni/ZnO and Niγ-Fe2O3Nanocomposites". Journal of Nanomaterials 2007 (2007): 1–16. http://dx.doi.org/10.1155/2007/27437.
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A comparative study at the ambient temperature of the ferromagnetic resonance (FMR) spectra of Ni/ZnO andNi/γ-Fe2O3nanocomposites (NCs) is reported. A microstrip transmission line technique was used to measure the FMR profiles and linewidths in the 8–24 GHz frequency range. The samples were placed at the center of a microstrip line where the derivative of the absorbed power was measured using a standard ac field modulation technique (10 Oe amplitude) and lock-in detection. The analysis of the FMR spectra can be interpreted as arising from aggregates of magnetic nanoparticles, each of which resonates in an effective magnetic field composed of the applied field, the average (magnetostatic) dipolar field, and the randomly oriented magnetic anisotropy field. It is found that frequency and applied magnetic field strongly influence the lineshape of the FMR spectra. Two observations are identified within the FMR spectra. On the one hand, the resonance field increased linearly with frequency as expected from uniform mode theory and yielded a Landégfactor in the range 1.48–2.05. On the other hand, there is no clear correlation between FMR linewidths and frequency. Inhomogeneity-based line-broadening mechanisms, due to the damping of surface/interface effects and interparticle interaction, affect the FMR effective linewidth.
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Молодід, О. C., В. О. Поколенко, О. О. Молодід, Р. О. Плохута i І. В. Мусіяка. "DIAGNOSIS OF USEFUL USEFULNESS OF BUILDING STRUCTURES AS A PREREQUISITE FOR CONTINUING THEIR LIFE CYCLE". Building production, nr 71 (22.05.2023): 21. http://dx.doi.org/10.36750/2524-2555.71.21-27.
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Normative documents regulate the periodic inspection of buildings and structures or their parts in order to establish their technical condition at the time of the inspection to ensure further reliable and safe operation. The result of the inspection is a technical report with conclusions and recommendations on methods of eliminating the identified defects or structure damages.Usually, during the preliminary visual inspection of the building structures the presence of damage defects is established and the need for additional special inspections with the use of special equipment.To detect structural defects in the form of inhomogeneity of the material, reducing its strength, cavities and cracks in the structures, reinforcement parameters (diameter, pitch, thickness of the protective layer), etc. use mechanical, acoustic, magnetic, radiation, electric, electromagnetic, visual etc. methods. The article presents the features of each method and devices that are commonly used in Ukraine and abroad (their principles of operation, features of use and capabilities).. Methods for determining the humidity of concrete are given. Examples of using digital portable microscope and mini camcorder. Modern methods of inspection of structures of highrise buildings and structures for detection of defects and damages are analysed.Experience of inspections of building structures shows that during inspections it is necessary to pay attention to even the smallest damages and to consider action of all possible factors. After all, a wellperformed survey will allow you to choose the right and rationally justified methods of repair and restoration work.
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He, Jingang, Hang Yuan, Zhong Su, Bin Zhao, Zhe Kuang i Pengfei Song. "Analysis of Information Transmission Characteristics Based on Adaptive Ground Electrode Current Field". Applied Sciences 13, nr 7 (28.03.2023): 4297. http://dx.doi.org/10.3390/app13074297.
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The information transmission mechanism of the ground electrode current field uses a very low-frequency electrical signal, which is applied to the two electrodes driven into the soil layer or the collapsed body of the tunnel to form a current field in the rock layer or soil layer. Signal detection is created via the strong penetration of wireless information transmission. This research focuses on various electromagnetic effects, such as polarization, magnetization, and the transmission of electromagnetic waves under the influence of different media, such as rock, sand, reinforced concrete, and air voids. The influence of these adaptive electromagnetic effects on the transmission of electromagnetic waves is mainly reflected in the reflection, refraction, and attenuation of electromagnetic wave signals. The inhomogeneity of the earth medium, the influence of topographic features, and multi-path transmission all cause signal distortion, fading, or changes in the direction of electromagnetic wave propagation. By studying the three physical quantities of magnetic permeability, permittivity, and conductivity, the electromagnetic characteristics of the earth medium are described to research the information transmission characteristics of the earth electrode current field.
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Ahern, Adam T., Ramachandran Subramanian, Georges Saliba, Eric M. Lipsky, Neil M. Donahue i Ryan C. Sullivan. "Effect of secondary organic aerosol coating thickness on the real-time detection and characterization of biomass-burning soot by two particle mass spectrometers". Atmospheric Measurement Techniques 9, nr 12 (22.12.2016): 6117–37. http://dx.doi.org/10.5194/amt-9-6117-2016.
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Abstract. Biomass burning is a large source of light-absorbing refractory black carbon (rBC) particles with a wide range of morphologies and sizes. The net radiative forcing from these particles is strongly dependent on the amount and composition of non-light-absorbing material internally mixed with the rBC and on the morphology of the mixed particles. Understanding how the mixing state and morphology of biomass-burning aerosol evolves in the atmosphere is critical for constraining the influence of these particles on radiative forcing and climate. We investigated the response of two commercial laser-based particle mass spectrometers, the vacuum ultraviolet (VUV) ablation LAAPTOF and the IR vaporization SP-AMS, to monodisperse biomass-burning particles as we sequentially coated the particles with secondary organic aerosol (SOA) from α-pinene ozonolysis. We studied three mobility-selected soot core sizes, each with a number of successively thicker coatings of SOA applied. Using IR laser vaporization, the SP-AMS had different changes in sensitivity to rBC compared to potassium as a function of applied SOA coatings. We show that this is due to different effective beam widths for the IR laser vaporization region of potassium versus black carbon. The SP-AMS's sensitivity to black carbon (BC) mass was not observed to plateau following successive SOA coatings, despite achieving high OA : BC mass ratios greater than 9. We also measured the ion fragmentation pattern of biomass-burning rBC and found it changed only slightly with increasing SOA mass. The average organic matter ion signal measured by the LAAPTOF demonstrated a positive correlation with the condensed SOA mass on individual particles, despite the inhomogeneity of the particle core compositions. This demonstrates that the LAAPTOF can obtain quantitative mass measurements of aged soot-particle composition from realistic biomass-burning particles with complex morphologies and composition.
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Aruna Kumar, S. V., Ehsan Yaghoubi i Hugo Proença. "A Fuzzy Consensus Clustering Algorithm for MRI Brain Tissue Segmentation". Applied Sciences 12, nr 15 (22.07.2022): 7385. http://dx.doi.org/10.3390/app12157385.
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Brain tissue segmentation is an important component of the clinical diagnosis of brain diseases using multi-modal magnetic resonance imaging (MR). Brain tissue segmentation has been developed by many unsupervised methods in the literature. The most commonly used unsupervised methods are K-Means, Expectation-Maximization, and Fuzzy Clustering. Fuzzy clustering methods offer considerable benefits compared with the aforementioned methods as they are capable of handling brain images that are complex, largely uncertain, and imprecise. However, this approach suffers from the intrinsic noise and intensity inhomogeneity (IIH) in the data resulting from the acquisition process. To resolve these issues, we propose a fuzzy consensus clustering algorithm that defines a membership function resulting from a voting schema to cluster the pixels. In particular, we first pre-process the MRI data and employ several segmentation techniques based on traditional fuzzy sets and intuitionistic sets. Then, we adopted a voting schema to fuse the results of the applied clustering methods. Finally, to evaluate the proposed method, we used the well-known performance measures (boundary measure, overlap measure, and volume measure) on two publicly available datasets (OASIS and IBSR18). The experimental results show the superior performance of the proposed method in comparison with the recent state of the art. The performance of the proposed method is also presented using a real-world Autism Spectrum Disorder Detection problem with better accuracy compared to other existing methods.
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Mori, Yuki, Chiyuri Komori i Gen Inoue. "(Digital Presentation) Prediction of an in-Plane Anomalous Current Using Numerical Simulation and Machine Learning". ECS Meeting Abstracts MA2022-02, nr 6 (9.10.2022): 604. http://dx.doi.org/10.1149/ma2022-026604mtgabs.
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Even normally shipped batteries may contain disturbing factors such as very small amounts of foreign matter or structural inhomogeneity, which can cause serious accidents such as thermal runaway or explosions. Since dismantling and identifying the cause is time-consuming and costly, nondestructive techniques for identifying the cause are required. A method for detecting abnormal current distribution by magnetic field inverse analysis has been proposed as one such method, but it is difficult to directly elucidate the factors that cause the abnormal current distribution itself. In this study, we first focused on the effect of different separator structures and analyzed the in-plane directional current distribution using machine learning in order to construct a non-destructive model for estimating the causes. A one-dimensional model based on porous electrode theory [1] was used. Constant current charging, homogeneous electrode layer structure, uniform Li concentration in active material particles, and isothermal conditions were assumed. The electrode layer was assumed to be a porous body consisting of active material, electrolyte, and auxiliary materials (conductivity assistant and binder). Using the previously reported structural information and physical properties [2], [3], Case 1 was a coin cell using LiNi1/3Co1/3Mn1/3O2 as the cathode active material, and Case 2 was a laminated cell using LiCoO2 as the cathode active material. The anode active material was graphite and the electrolyte was 1.0 M LiPF6 solution in EC・DEC solvent for both Case 1 and 2. The degree of flexure of the cathode and anode was determined using the formulas from previous studies [4]. Cross-sectional images of the actual biaxially oriented separator were obtained using a focused ion beam scanning electron microscope, and the three-dimensional simulated structure was reproduced based on these images (Sep. A). Similarly, a nonwoven fabric structure (Sep. B) and a foam structure (Sep. C) were also reproduced. Since the collector foils are connected in-plane, the potentials at both ends of the cell must be uniform. Under this constraint, the ion current distribution can be estimated depending on the in-plane structure distribution of the separator. In this study, the correlation between the local porosity (ε) of the separator and the local ion current (denoted as C-rate) was determined using a nonlinear regression method called Support Vector Regression (SVR) [5]. 100 points were taken randomly from 0.4~1.0 and 5~10 for ε and C-rate, respectively, and used as explanatory variables. Each charging curve was compared with the charging curve at the in-plane mean value of (ε, C) = (0.545, 7.5), and the RMSE (root mean square error) of the voltage was calculated as the objective variable. The in-plane reaction distribution was obtained from the voltage error predicted from ε and C-rate by SVR and the porosity distribution of the separator. The mesh size was 40 nm/pixel. For each separator, the difference between high and low reaction profiles was more clearly observed in Case 2. The reaction overvoltage distribution at a certain point in Case 2 was acquired, and it was confirmed that the reaction was concentrated near the separator of the negative electrode. This also made it possible to estimate the Li deposition point, which is the starting point of degradation. Using machine learning to analyze the in-plane current distribution, it was found that the current distribution differs depending on the electrode conditions even for the same separator. We will use this technology to develop a technique for identifying factors based on the current distribution obtained by nondestructive measurement. References [1] G. M. Goldin et al., Electrochim. Acta., 64 118 (2012). [2] G. Inoue et al., J. Chem. Eng. Japan., 54 (5) 207-212 (2021). [3] K. Ikeshita et al., ECS Trans., 75 (20) 165-172 (2017). [4] G. Inoue et al., J. Pow. Sour., 342, 476 (2017). [5] C. Cortes et al., Mach. Learn., 20 (3) 273-297 (1995).
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Yamane, Yuji, Isao Ando, Fredric L. Buchholz, Alan R. Reinhardt i Shulamith Schlick. "Detection of Spatial Inhomogeneity in Poly(acrylic acid) Gels by Measuring Time-Dependent Diffusion Coefficients of a Probe in NMR Experiments: Effect of the Degree of Cross-Linking and Degree of Swelling". Macromolecules 37, nr 26 (grudzień 2004): 9841–49. http://dx.doi.org/10.1021/ma048343v.
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Kmiecik, Barbara, i Jerzy Detyna. "Detection of inhomogeneity by the observation of the surface of the material simulating biological tissues". Bio-Algorithms and Med-Systems 15, nr 1 (22.02.2019). http://dx.doi.org/10.1515/bams-2018-0043.
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Abstract This paper presents a research which involves the observation of the movement of points presented on a material surface under the influence of mechanical extortion. Tests were performed using two 15 mm silicone layers, one of which contained 1 mm thick elements of nitrile-butadiene rubber. Analysed materials were structurally heterogeneous tissue phantoms. Test results that were obtained indicated that the developed method allows detecting inhomogeneity and its approximate location, what may be used in pathological state prevention.
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Frederikse, H. P. R., X. T. Ying i A. Feldman. "Thermal Properties of Non-Metallic Films by Means of Thermal Wave Techniques". MRS Proceedings 142 (1988). http://dx.doi.org/10.1557/proc-142-289.
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AbstractThe propagation of a thermal wave into a thin film or coating depends on the thermal properties of the material. Consequently, thermal wave generation and detection can be used to obtain the heat conductivity of the material. The method is also useful because thermal wave propagation is sensitive to inhomogeneity, porosity, inclusions, voids, and delaminations. The results of two specific applications of the thermal wave technique are presented, the heat resistance of oxide coatings and of diamond films.
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"Line-focus-beam acoustic microscope and its application to inhomogeneity detection in saw device materials". NDT International 23, nr 1 (luty 1990): 45. http://dx.doi.org/10.1016/0308-9126(90)91516-v.
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Okamoto, Yasunao, Erika Okita, Daigo Yamamoto, Satoshi Nakata i Akihisa Shioi. "Detection of Inhomogeneity After Mixing Solutions by Analyzing the Chemical Wave Pattern in the Belousov-Zhabotinsky Reaction". Frontiers in Physics 10 (4.05.2022). http://dx.doi.org/10.3389/fphy.2022.895824.
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The correlation between BZ reaction and mixing state has been studied for decades, and the researchers are trying to apply it to chemical engineering. We observed a chemical wave pattern in the Belouzov-Zhabotinsky (BZ) reaction based on the inhomogeneity after mixing BZ and ferroin solutions with a mixing method named the rotation-and-stop method. A one-dimensional chemical wave appeared for large inhomogeneity in mixing. The frequency and wavenumber decreased with decreasing degree of inhomogeneity. In an almost perfectly mixed state, the wavenumber significantly reduced and approached the global oscillation. The degree of mixing could be efficiently determined by this reported method. Perfect mixing has never been realized in natural and biological systems. The results of this study can be applied to estimate the degree of mixing in a solution that is not being stirred after the mixing process.
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Cai, Xiaojie, Qian Yu, Chang Huang, Bin Tang, Shihui Zhou, Xiaohu Wang, Xiuping Yue i Zhijia Sun. "Performance optimization of the scintillator neutron detectors for EMD in CSNS". Chinese Physics B, 25.05.2023. http://dx.doi.org/10.1088/1674-1056/acd8a2.
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Abstract Chinese Spallation Neutron Source (CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the Engineering Materials diffractometer (EMD) will be installed between 2019- 2023. This instrument requires the neutron detectors with the cover area near 3m2 in two 90° neutron diffraction angle position, the neutron detect efficiency better than 40%@1Å, and the spatial resolution better than 4mm×200mm in horizontal and vertical directions respectively. We have developed an one-dimensional position sensitive neutron detector based on the oblique 6LiF/ZnS(Ag) scintillators, wavelength shifting fibers and SiPMs (Silicon Photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, need to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20 (Beam Line 20) of CSNS. Using water sample, the neutron beam with Φ5mm exit hole was dispersed relate evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one is improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.
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Eyinla, Dorcas S., Michael A. Oladunjoye, Abel I. Olayinka i Boris B. Bate. "Rock physics and geomechanical application in the interpretation of rock property trends for overpressure detection". Journal of Petroleum Exploration and Production Technology, 21.11.2020. http://dx.doi.org/10.1007/s13202-020-01039-4.
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AbstractOne of the complexities of geomechanical study is in the classification of rock’s properties and overpressured intervals—a knowledge which is not only essential for well safety and cost-effective drilling, but crucial in evaluating exploration risk factors and ensuring a successful hydraulic fracturing program. In this study, a more robust prediction of reservoir pressure regime is presented, where the geomechanical distributions of the rock give a distinct correlation. Three wells from the Niger Delta Basin were studied using empirical equations to estimate the elastic properties, wave velocities and the rock physics parameters for each well. From the results obtained, the velocities of compressional wave (Vp) and shear wave (Vs) decrease as porosity increases. Also, a linear correlation exists between Poisson’s ratio and Vp/Vs, where both variables showed distinct behavior and similar trend serving as useful tools for lithology identification. Another significant observation is the acoustic impedance of the materials which decreases with increasing porosity. Meanwhile, the depth plot of the impedance showed divergence and scattering away from the supposed linear trend. While inhomogeneity of the rock materials and disequilibrium compaction of sediments may account for this scattering, the variation of geomechanical distributions in this study revealed that pore pressure has a first order effect on the elastic strength of formations, also, under normal pore pressure conditions, acoustic impedance increases linearly with depth.
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Chichibu, S. F., T. Sota i S. Nakamura. "Role of Localized Quantum Well Excitons in InGaN Quantum Well Structure Correlated with Microstructural Analysis". MRS Proceedings 639 (2000). http://dx.doi.org/10.1557/proc-639-g9.3.
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ABSTRACTInxGa1−xN multiple-quantum-well laser diode structure, which lased at 405 nm, was shown to have atomically-flat interfaces between each layer. Nanometer-probe compositional analysis showed that InN mole fraction, x, in the wells and barriers are approximately 6 % and 2 %, respectively, which agreed with the result obtained from high-resolution x-ray diffraction measurement. The Stokes-like shift (SS) at 300 K was 49 meV, being approximately 65 % of the luminescence linewidth. The localization depth, E0, of qunatum-well (QW) excitons was estimated to be 35 meV at 300 K though the compositional fluctuation in the well was as small as 1 % or less (detection limit) within adjacent 20-30 nm lateral length scale. Since the well thickness fluctuation is insufficient to reproduce SS or E0, effective bandgap inhomogeneity is attributed to be due to large bandgap bowing in InGaN. The spontaneous emission was thus assigned as being due to the recombination of QW excitons weakly localized in exponential tail-type potential minima in the QW. The size of localization is smaller than the quantum-disk [M. Sugawara, Phys. Rev. B 51, 10743 (1995)]-size. Such small bandgap inhomogeneity can be leveled by injecting high density carriers under lasing conditions, which can explain the general experimental finding that the quantum efficiency decreases with increasing carrier density in InGaN QW devices due to free carrier trapping into threading dislocations.
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Abuladze, Liya, Dmitriy S. Semenov, Olga Y. Panina i Yuriy A. Vasilev. "Optimized biparametric magnetic resonance imaging protocol for prostate cancer detection." Digital Diagnostics, 23.08.2022. http://dx.doi.org/10.17816/dd108484.
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Aim:
To develop a biparametric MRI protocol optimized for the existing MRI scanners for the diagnosis of PCa, allow to screen and early detect of neoplasms as early as possible. At the same time, the protocol should be as close as possible to the current PI-RADS v2.1 recommendations and meet the requirements of effective workflow in radiology department.
Materials and Methods:
Preliminary analysis of the prostate MRI scanning in medical organizations of the Moscow Health Care Department showed the absence of the unified approach. Using the method of iterative adjustment of scanning parameters, we adjusted the protocol ensuring acceptable quality with maximum available compliance with PI-RADS v2.1.
To quantify the quality of the images we used the MRI phantom recommended by the American College of Radiology (ACR).
Results:
The biparametric protocol was developed for the Excelart Vantage 1.5 T tomograph, including T2-weighted images in three planes and diffusion-weighted images, which is less than 11 minutes in total. At the same time, image quality parameters (intensity inhomogeneity, nonlinearity, resolution, and slice thickness) were within the MRI manufacturer's acceptable ranges.
Conclusion:
The prostate may be evaluated effectively by using the proposed MRI protocol. Its launching into the practice tends to have a significant influence on detection of PCa in men. It should be noted that the whole duration of the protocol provides a possibility to supplement it with any sequences, depending on the final purpose of investigation.
Keywords: prostate cancer, biparametric magnetic resonance imaging, standardization
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Khastavaneh, Hassan, i Hossein Ebrahimpour Komleh. "MMTDNN: Multi-view Massive Training Deep Neural Network for Segmentation and Detection of Abnormal Tissues in Medical Images". Frontiers in Biomedical Technologies, 22.04.2020. http://dx.doi.org/10.18502/fbt.v7i1.2722.
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Purpose: Automated segmentation of abnormal tissues in medical images is considered as an essential part of those computer-aided detection and diagnosis systems which analyze medical images. However, automated segmentation of abnormalities is a challenging task due to the limitations of imaging technologies and complex structure of abnormalities, including low contrast between normal and abnormal tissues, shape diversity, appearance inhomogeneity, and the vague boundaries of abnormalities. Therefore, more intelligent segmentation techniques are required to tackle these challenges.
Materials and Methods: In this study, a method, which is called MMTDNN, is proposed to segment and detect medical image abnormalities. MMTDNN, as a multi-view learning machine, utilizes convolutional neural networks in a massive training strategy. Moreover, the proposed method has four phases of preprocessing, view generation, pixel-level segmentation, and post-processing. The International Symposium on Biomedical Imaging (ISBI)-2016 dataset is used for the evaluation of the proposed method.
Results: The performance of the proposed method has been evaluated on the task of skin lesion segmentation as one of the challenging applications of abnormal tissue segmentation. Both qualitative and quantitative results demonstrate outstanding performance. Meanwhile, the accuracy of 0.973, the Jaccard index of 0.876, and the Dice similarity coefficient of 0.931 have been achieved.
Conclusion: In conclusion, the experimental result demonstrates that the proposed method outperforms stateof-the-art methods of skin lesion segmentation.