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Interfacial adhesion between embedded fibre optic sensors and epoxy matrix in composites
摘要： Fibre optic (FO) sensors are becoming increasingly popular for different applications in structural monitoring. Among their excellent properties, a strong interest for this type of sensors are represented by the possibility of embedding FOs inside composite components. In this case, one of the factors that significantly influence the efficiency of the whole Structural Health Monitoring (SHM) system is the interfacial adhesion between FO sensors and the host material. The main objective of this work is to investigate the interfacial adhesion between embedded fibre optic sensors and epoxy matrix to find the best type of optical fibre to be used in epoxy matrices to produce smart composites. Four types of optical fibres with different diameters and coatings (i.e. polyimide, polyacrylate and ormoceramic) were used. Pull-out tests were carried out and different methods were used to obtain the composite/optical fibre interfacial properties. Finally, an optical microscopy and Scanning Electron Microscopy (SEM) analysis were performed to characterize the fibre/matrix interfaces. It was found that the optical fibre that presented the highest energy required for interface rupture and, consequently, less invasiveness to the host material was the ormoceramic fibre with the smallest diameter.
关键词： Structural health monitoring,Pull-out test,interfacial adhesion,fibre optics sensors
更新于2025-09-23 15:23:52
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Long-term analysis of PV module with large-area patterned anti-reflective film
摘要： Due to the PV modules are exposed to the external environment, it is necessary to clean or replace the protective glass upon contamination. In this study, we demonstrate a large-area and flexible anti-reflective film with moth-eye pattern fabricated by using a highly straightforward process: nanoimprint lithography. In addition, the fabricated anti-reflective film exhibits self-cleaning capability owing to the hydrophobic self-assembled-monolayer-coated surface. The fabricated anti-reflective film was attached to the surface of photovoltaic (PV) modules and placed outdoor to conduct a seven-month field test in order to observe the increase in the conversion efficiency of the PV modules as a result of the effect of the anti-reflective film. Two types of patterns, moth-eye pattern and micro-cone pattern, were used as the anti-reflective patterns; these were conveniently fabricated by the ultraviolet-nanoimprint lithography process, which does not use vacuum or high-temperature process. In the seven-month analysis, the moth-eye patterned film was observed to exhibit a transmittance that is 5.0% higher than that of the flat film, whereas the PV module with the moth-eye patterned film on its surface exhibited a conversion efficiency that is 2.85% higher than that of the PV module with the flat film.
关键词： Field test,Long-term,Moth-eye,Anti-reflective,Nanoimprint lithography
更新于2025-09-23 15:23:52
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Fibre Bragg grating sensor applications for structural health monitoring
摘要： Purpose – Structural health monitoring (SHM) has become an attractive subject in aerospace engineering ?eld considering the opportunity to avoid catastrophic failures by detecting damage in advance and to reduce maintenance costs. Fibre Bragg Grating (FBG) sensors are denoted as one of the most promising sensors for SHM applications as they are lightweight, immune to electromagnetic effects and able to be embedded between the layers of composite structures. The purpose of this paper is to research on and demonstrate the feasibility of FBG sensors for SHM of composite structures. Design/methodology/approach – Applications on thin composite beams intended for SHM studies are presented. The sensor system, which includes FBG sensors and related interrogator system, and manufacturing of the beams with embedded sensors, are detailed. Static tension and torsion tests are conducted to verify the effectiveness of the system. Strain analysis results obtained from the tests are compared with the ones obtained from the ?nite element analyses conducted using ABAQUS? software. In addition, the comparison between the data obtained from the FBG sensors and from the strain gauges is made by also considering the noise content. Finally, fatigue test under torsion load is conducted to observe the durability of FBG sensors. Findings – The results demonstrated that FBG sensors are feasible for SHM of composite structures as the strain data are accurate and less noisy compared to that obtained from the strain gauges. Furthermore, the convenience of obtaining reliable data between the layers of a composite structure using embedded FBG sensors is observed. Practical implications – Observing the advantages of the FBG sensors for strain measurement will promote using FBG sensors for damage detection related to the SHM applications. Originality/value – This paper presents applications of FBG sensors on thin composite beams, which reveal the suitability of FBG sensors for SHM of lightweight composite structures.
关键词： Torsion test,Tension test,Structural health monitoring,Composite beams,Fibre Bragg grating sensors
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - Sheffield (2018.7.8-2018.7.11)] 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - An Adaptive Sequential Competition Test for Beam Selection in Massive MIMO Systems
摘要： To solve the problem of beam selection or capturing the highest possible signal power, we propose a sequential test that can adapt to the SNR operating point and speed up the selection procedure in terms of the number of required observations in comparison to a perfectly tuned fixed length test assuming genie knowledge. The speed up gets higher for lower SNR and becomes of particular interest in massive Multiple Input Multiple Output (MIMO) systems using beamforming, where the number of candidate beams is large and exhaustive search can cause intolerable delay due to limited channel coherence time.
关键词： Generalized Likelihood Ratio Test,Millimeter wave,Sequential Test,Beam Selection,Massive MIMO
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Iasi, Romania (2018.10.18-2018.10.19)] 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Aspects Regarding Disturbances Produced by Fluorescent Tubes
摘要： This paper has a strong applicative character. There is presented a modern system for monitoring dynamic states, carried out with the help of a data acquisition board. It is insisted upon an original monitoring program conceived by the paper team. There are presented then two applications of using this system: a) (experimental) analysis of disturbances produced by a fluorescent tube; b) analysis of disturbances produced by a LED tube. A special attention is paid to the experimental aspects which emphasize the waveforms of the currents corresponding to some fluorescent tubes (in a few representative operation states). Finally, there are presented conclusions, which have been obtained by finalizing the research and the afferent bibliography.
关键词： LED tube,harmonic analysis,test,fluorescent tube,disturbances
更新于2025-09-23 15:22:29
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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - Low Temperature (80 °C) Sinterable Particle Free Silver Ink for Flexible Electronics
摘要： For the emerging field of flexible printed electronics, ink compatibility with substrate is always required. However, most of the commercial silver nanoparticle-based inks are not compatible with flexible substrates, as they need high- sintering temperatures (~150-250 0C). In addition, silver nanoparticle-based inks have several serious problems such as a complex synthesis protocol, high cost, particle aggregation, nozzle clogging, reduced shelf life, and jetting instability. These shortcomings in conductive inks are barriers for their wide spread use in practical applications. In this work, we demonstrate a silver-organo-complex (SOC) based particle free silver ink which can decompose at 80 0C and becomes conductive at this low temperature. The inkjet-printed film from this ink exhibits not only high conductivity but also excellent jetting and storage stability. To demonstrate the suitability of this ink for flexible electronics, an inkjet-printed film on flexible polyimide substrate is subjected to bending and crushing tests. The results before and after flexing and crushing are very similar, thus verifying the excellent tolerance against bending and crushing for this ink as compared to the commercial nanoparticles based ink.
关键词： low-temperature sintering,silver-organo-complex (SOC) ink,bending and crushing test,inkjet-printing,flexible
更新于2025-09-23 15:22:29
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Numerical and experimental analysis of the effect of metal tie layers on improving electrical properties of gold coated poly (dimethylsiloxane) flexible multi-layered films during folding
摘要： To improve folding electrical properties of flexible electronics, this study presents a new adhesive stress analysis of depositing an adhesion layer between the conductive film electrode and the flexible substrate during folding test by a folding test platform. The folding test platform controls folding curvature of the flexible conductive substrates, folding times, and velocities in this study. Moreover, the electrical properties of flexible conductive substrates are measured during folding testing by the folding test platform. Eventually, this study successfully analyzes residual strain, adhesive stress, and electrical properties of flexible gold coated on polydimethylsiloxane substrates with chromium, nickel, and titanium adhesion layers up to 0.5/cm folding curvature during folding testing. The chromium adhesion layer had the best performance based on the largest adhesive stress, only 3.74 X resistance increase and 4.53 X maximum resistance up to 0.5/cm folding curvature during folding test by a folding test platform. The experimental result with chromium adhesion layer is consistent with adhesive stress analysis and provides a better adhesive strength between gold and polydimethylsiloxane than nickel and titanium materials for folding test. Therefore, adhesive stress analysis is adapted to evaluate the foldable electronics performance for improving folding characteristics easier.
关键词： flexible electronics,Folding electrical property,folding test platform,adhesive stress analysis,adhesion layer
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Statistical Signal Processing Workshop (SSP) - Freiburg im Breisgau, Germany (2018.6.10-2018.6.13)] 2018 IEEE Statistical Signal Processing Workshop (SSP) - A Group Invariance Approach to a Very Weak LFM Signal Detection
摘要： This paper considers the detection of a very low signal to noise ratio (SNR), linear frequency modulated (LFM) radar waveforms from data received by a wideband receiver. The optimal method involves a computationally intensive two dimensional search. Faster alternatives, include the discrete ambiguity approach to LFM detection/estimation which is computationally efficient but is well known to be applicable only at moderately high SNR, while the windowed Fourier transform can be used to detect low SNR signals, but only for quite small chirp rates. Here we utilize multiple time and frequency shifts applied to the received data to structure the problem as one of detection of a multi-channel unknown rank-one component in noise. Our method which involves only a one dimensional search over chirp rate, works at very low SNR and can handle multiple signals and interferers The generalized-likelihood ratio test (GLR), the Bayesian test are discussed and compare with the generalized coherence test. The detection performance are demonstrated through numerical simulations.
关键词： GLRT,LFM signal,rank-one signal,Bayesian test,generalized coherence
更新于2025-09-23 15:22:29
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Energy yield prediction of a bifacial PV system with a miniaturized test array
摘要： Because of the sensitivity on multiple additional factors, compared to monofacial standard installations, the simulation and prediction of a bifacial PV arrays yield is by far more complicated and less reliable. Accordingly, the determination of optimized installation conditions is considerably less straightforward for bifacial installations. Due to the pronounced dependencies also the assignability of otherwise applied installation conditions to similar systems is limited. Because of the low accuracy of the traditional approaches to predict the bifacial system output the use of a miniaturized test rig might be an interesting option. Provided that the results can be assigned to measurements at real systems it can be used as a cheap and flexible testing device. Miniaturized devices could be used in long-term trials for yield measurements at specific locations, to identify optimum installation conditions or to validate simulation algorithms. Running several test rigs with different configurations in parallel would enable a direct comparison. The small size of a miniaturized rig also allows a fast change of the set-up, which is an interesting feature to test the respective impact at otherwise almost unchanged conditions in short-term tests. In this paper we report on a test device which is a miniaturized (1:12) replica of an existing PV array with commercial bifacial modules. The measurement data of both systems are compared in order to investigate if there is a clear assignability. A unique feature of the large test field, a permanent and automated variation of the tilt angle, is also transferred to the miniaturized version. Accordingly, the whole tilt angle range is tested and potential tilt angle dependent effects are revealed. Based on the obtained data we give an estimation of the error in the prediction accuracy and discuss options for possible improvements.
关键词： Energy yield prediction,Bifacial,Tilt angle,Test system
更新于2025-09-23 15:22:29
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Semi-Automatic Red Blood Cells Counting in Microscopic Digital Images
摘要： The main purpose of this study is to employ the modern technologies and techniques to semi-automate the quantification process of the Red Blood Cells in Microscopic thin blood smear digital images. The process needs to be more accurate, efficient and universal then the currently practiced methods. The study considers the process to be semi-automated for two reasons, i.e. due to the critical aspect life and due to the diverse nature of the Red Blood Cells in cluster formation. The Methodology of this study involved interactive simple cuts and morphological operations for splitting clusters of Red Blood Cells while counting is carried out through labeling matrix. The Red Blood Cells counting is part of the complete blood count test and is frequently suggested by the Physician to know the number of Red Blood Cells in the patient’s body. The proposed method considers for counting process of the Red Blood Cells first split the clusters and then count the Red Blood Cells. The proposed method achieved an overall True Positive Rate (TPR) of 0.997%, True Negative Rate (TNR) of 0.00265%, accuracy of 0.998% and average error rate of 0.001375% tested on 50 images, data set also on the same number of images linear correlation coefficient R2 is 0.997 between manual and semi-automatic counting of Red Blood Cells.
关键词： rouleaux splitting,healthcare applications,Clustered red blood cells,complete blood test,occlusions
更新于2025-09-23 15:22:29