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[IEEE 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED) - Toulouse, France (2019.8.27-2019.8.30)] 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED) - Parametric degradation model of OLED using Design of Experiments (DoE)
摘要： This article presents an original parametric degradation model using Design of Experiments. This method is based on the estimation of a Weibull function under accelerated conditions. It is applied on cold white organic light emitting diodes OLEDs from Philips with a 10000 hrs theoretical lifetime. Accelerated degradation using thermal and electrical stress is tested. The predicted degrading model is a function of time, temperature, current density and their interaction. It illustrates the behaviour of the degradation of the OLED using multiple stress factors without really knowing the physics of these degradations. The proposed model is tested on experimental data for different luminances. The average error of the predicted model compared to real values is around 3 %. The proposed model is then compared to a previously developed lifespan model. The results obtained with the present approach are closer to the real values.
关键词： Degradation,Electrical stresses,Modeling,Thermal stresses,Design for Experiments,Accelerated aging,Organic light emitting diodes,Weibull distribution,Lifetime estimation
更新于2025-09-12 10:27:22
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Novel laser textured surface designs for improved zirconia implants performance
摘要： The development of new surface designs to enhance the integration process between surgically placed implants and biological tissues remains a challenge for the scientific community. In this way and trying to overcome this issue, in this work, laser technology was explored to produce novel textures on the surface of green zirconia compacts produced by cold pressing technique. Two strategies regarding line design (8 and 16 lines design) and different laser parameters (laser power and number of laser passages) were explored to assess their influence on geometry and depth of created textures. The produced textures were evaluated with Scanning Electron Microscopy (SEM) and it was observed that well-defined textured surfaces with regular geometric features (cavities or pillars) were obtained by laser combining different strategies lines design and parameters. The potential of proposed textures was also evaluated regarding surface wettability, friction performance (static and dynamic coefficient of friction evolution) against bone, aging resistance and flexural strength. Results demonstrated that all the produced textures display a super hydrophilic or hydrophilic behavior. Regarding the friction behavior, it was experimentally observed a high initial static coefficient of friction (COF) for all produced textures. Concerning the aging resistance, all the textured surfaces revealed a low monoclinic content, less than 25% after 5?h of hydrothermal aging. The flexural strength results showed that the mechanical resistance of zirconia was not significantly compromised with the laser action. Based on the obtained results, it is possible to prove that the processing route used for manufacturing the new and different surface designs (cold pressing technique followed by laser texturing) showed to be particularly effective for the production of zirconia implants with customized surface designs according to the properties required in a specific application. These new surface designs besides to enhance the surface wettability and also to improve the fixation at the initial moment of the implantation, do not significantly compromise the resistance to aging and the mechanical performance of zirconia. Hence, a positive impact on the long-term performance of the zirconia implants may be expected with the proposed novel laser textured surface designs.
关键词： Flexural strength,Aging resistance,Zirconia,Surface wettability,Coefficient of friction,Laser surface texturing
更新于2025-09-12 10:27:22
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Monitoring of Thermal Aging of Aluminum Alloy via Nonlinear Propagation of Acoustic Pulses Generated and Detected by Lasers
摘要： Nonlinear acoustic techniques are established tools for the characterization of micro-inhomogeneous materials with higher sensitivity, compared to linear ultrasonic techniques. In particular, the evaluation of material elastic quadratic nonlinearity via the detection of the second harmonic generation by acoustic waves is known to provide an assessment of the state variation of heat treated micro-structured materials. We report on the first application for non-destructive diagnostics of material thermal aging of finite-amplitude longitudinal acoustic pulses generated and detected by lasers. Finite-amplitude longitudinal pulses were launched in aluminum alloy samples by deposited liquid-suspended carbon particles layer irradiated by a nanosecond laser source. An out-of-plane displacement at the epicenter of the opposite sample surface was measured by an interferometer. This laser ultrasonic technique provided an opportunity to study the propagation in aluminum alloys of finite-amplitude acoustic pulses with a strain up to 5 × 10?3. The experiments revealed a signature of the hysteretic quadratic nonlinearity of micro-structured material manifested in an increase of the duration of detected acoustic pulses with an increase of their amplitude. The parameter of the hysteretic quadratic nonlinearity of the aluminum alloy (Al6061) was found to be of the order of 100 and to exhibit more than 50% variations in the process of the alloy thermal aging. By comparing the measured parameter of the hysteretic quadratic nonlinearity in aluminum alloys that were subjected to heat-treatment at 220 ?C for different times (0 min, 20 min, 40 min, 1 h, 2 h, 10 h, 100 h, and 1000 h), with measurements of yield strength in same samples, it was established that the extrema in the dependence of the hysteretic nonlinearity and of the yield strength of this alloy on heat treatment time are correlated. This experimental observation provides the background for future research with the application goal of suggested nonlinear laser ultrasonic techniques for non-destructive evaluation of alloys’ strength and rigidity in the process of their heat treatment.
关键词： laser ultrasonics,thermal aging,hysteretic acoustic nonlinearity,nonlinear acoustics
更新于2025-09-11 14:15:04
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Aging Effect of a Cu(In,Ga)(S,Se) <sub/>2</sub> Absorber on the Photovoltaic Performance of Its Cd‐Free Solar Cell Fabricated by an All‐Dry Process: Its Carrier Recombination Analysis
摘要： Cd-free Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells are fabricated by an all-dry process (a Cd-free and all-dry process CIGSSe solar cell) with aged CIGSSe thin film absorbers. The aged CIGSSe thin films are kept in a desiccator cabinet under partial pressure of oxygen of ≈200 Pa for aging time up to 10 months. It is reported for the first time that aged CIGSSe thin film with increased aging time results in significant enhancement of photovoltaic performance of Cd-free and all-dry process CIGSSe solar cells, regardless of the alkali treatment. Based on carrier recombination analysis, carrier recombination rates at the interface and in the depletion region of the Cd-free and all-dry process CIGSSe solar cells are reduced owing to avoidance of sputtering damage on CIGSSe absorber surface, which is consistent with the strong electron beam-induced current signal near CIGSSe surface after the increased aging time. It is implied that the interface and near-surface qualities are clearly improved through the increased aging time, which is attributable to the self-forming of Inx(O,S)y near CIGSSe surface, which acts as a buffer layer. Ultimately, the 22.0%-efficient Cd-free CIGSSe solar cell fabricated by all-dry process is achieved with the aged Cs-treated CIGSSe absorber with the aging time of 10 months.
关键词： all-dry process,EBIC measurements,Cd-free Cu(In,Ga)(S,Se)2 solar cells,aging time,carrier recombination rate
更新于2025-09-11 14:15:04
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Hair surface quality: Laser scattering as a tool for characterizing the surface condition and deposits from shampoos and conditioners
摘要： OBJECTIVES: The hair surface condition underlies many visually perceived attributes such as shine, color, and the 3D perception of a curly hair style. Many factors can alter the hair surface such as cumulated cleansing/styling regimens or chemical treatments which can lead to degradation of the cuticle edges and surface. Similarly, pollutants, sebum, and shampoo / conditioners can build up on the hair surface which are also perceivable to an observer. METHODS: The highly directive light of a laser is reflected and scattered by the surface of hair fibers into a circular pattern. The angular and spatial characteristics of this pattern reflect the hair geometry and the quality of the hair surface, i.e. the outer cuticle layer. Dark flat hair tresses were used to measure the impact of artificial sebum and shampoo / conditioner regimens on the cuticle surfaces. Also, longer single hair fibers from 4 volunteers were characterized for their surface changes from roots to tips, i.e. over the chronological age of the hair. RESULTS: The laser scattering shows clear changes in specular reflection characteristics from treatments and allows for the extraction of the cuticle inclination angle with respect to the hair axis. Deep cleansing or clarifying shampoos do partially restore the cuticle angle by removing residues on the hair surface while more conditioning systems can lead to changes in specular reflection angle and scattering, especially when multiple cycles of shampoo + conditioner treatments. Lastly, changes in hair surface can be traced over time of hair age by this approach and are consistent with frequency and nature of hair treatments. CONCLUSIONS: The method shows great potential for characterizing cleansing regimens in terms of their impact on the hair surface, either as single or multiple washes. Coverage or damage to the hair cuticles appears readily as an angle shift of the specular reflection while the quality of the surface topology has a direct impact on the angular width of the specular reflection thus affecting the shine band on a person’s head. Hair aging from root to tip can be quantified by laser scattering and correlates well with treatment events in time.
关键词： shampoo,hair surface,cuticle condition,conditioner,laser scattering,hair aging
更新于2025-09-11 14:15:04
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Optical Coherence Tomography Study of Retinal Changes in Normal Aging and After Ischemia
摘要： PURPOSE. Age-related thinning of the retinal ganglion cell axons in the nerve ?ber layer has been measured in humans using optical coherence tomography (OCT). In this study, we used OCT to measure inner retinal changes in 3-month-, 1-year-, and 2-year-old mice and after experimental anterior ischemic optic neuropathy (AION). METHODS. We used OCT to quantify retinal thickness in over 200 eyes at different ages before and after a photochemical thrombosis model of AION. The scans were manually or automatically segmented. RESULTS. In normal aging, there was 1.3-lm thinning of the ganglion cell complex (GCC) between 3 months and 1 year (P < 0.0001) and no further thinning at 2 years. In studying age-related inner retinal changes, measurement of the GCC (circular scan) was superior to that of the total retinal thickness (posterior pole scan) despite the need for manual segmentation because it was not contaminated by outer retinal changes. Three weeks after AION, there was 8.9-lm thinning of the GCC (circular scan; P < 0.0001), 50-lm thinning of the optic disc (posterior pole scan; P < 0.0001), and 17-lm thinning of the retina (posterior pole scan; P < 0.0001) in the 3-month-old group. Changes in the older eyes after AION were similar to those of the 3-month-old group. CONCLUSIONS. Optical coherence tomography imaging of a large number of eyes showed that, like humans, mice exhibited small, age-related inner retinal thinning. Measurement of the GCC was superior to total retinal thickness in quantifying age-related changes, and both circular and posterior pole scans were useful to track short-term changes after AION.
关键词： vision loss,optic neuropathy,aging,retinal ganglion cell,optical coherence tomography,animal model,anterior ischemic optic neuropathy
更新于2025-09-11 14:15:04
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MALDI Imaging Mass Spectrometry Spatially Maps Age-Related Deamidation and Truncation of Human Lens Aquaporin-0
摘要： PURPOSE. To spatially map human lens Aquaporin-0 (AQP0) protein modifications, including lipidation, truncation, and deamidation, from birth through middle age using matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS). METHODS. Human lens sections were water-washed to facilitate detection of membrane protein AQP0. We acquired MALDI images from eight human lenses ranging in age from 2 months to 63 years. In situ tryptic digestion was used to generate peptides of AQP0 and peptide images were acquired on a 15T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Peptide extracts were analyzed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) and database searched to identify peptides observed in MALDI imaging experiments. RESULTS. Unmodified, truncated, and fatty acid–acylated forms of AQP0 were detected in protein imaging experiments. Full-length AQP0 was fatty acid acylated in the core and cortex of young (2- and 4-month) lenses. Acylated and unmodified AQP0 were C-terminally truncated in older lens cores. Deamidated tryptic peptides (t0.9847 Da) were mass resolved from unmodified peptides by FTICR MS. Peptide images revealed differential localization of un-, singly-, and doubly-deamidated AQP0 C-terminal peptide (239–263). Deamidation was present at 4 months and increases with age. Liquid chromatography–MS/MS results indicated N246 undergoes deamidation more rapidly than N259. CONCLUSIONS. Results indicated AQP0 fatty acid acylation and deamidation occur during early development. Progressive age-related AQP0 processing, including deamidation and truncation, was mapped in human lenses as a function of age. The localization of these modified AQP0 forms suggests where AQP0 functions may change throughout lens development and aging.
关键词： deamidation,truncation,aging,MALDI IMS,in situ digestion,posttranslational modifications,ocular lens
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Langkawi, Malaysia (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Detection of Power Transformer Fault Conditions using Optical Characteristics of Transformer Oil
摘要： Power transformers are important in the power transmission and distribution network. A continuous monitoring of the transformer is important in ensuring the prolonged service of the transformer. This paper focuses on the characterization of transformer oil using optical detection method. 10 Transformer oil samples from the main tanks and 11 oil samples from the on-load-tap-changer (OLTC) were obtained for the optical characterization from 200 to 3300 nm. Based on the conventional results interpretation using dissolved gas analysis (DGA) and Duval Triangle, the optical characteristics of the samples in 2120 to 2220 nm clearly demonstrate the detection of electrical discharges of high energy (D2), electrical discharges of low energy (D1) and thermal faults at temperatures above 700°C (T3) faults. This approach provides a quicker and cheaper method to determine the condition of power transformers based on the optical characteristics of transformer oil.
关键词： spectrophotometer,On-load-tap-changer,main transformer tank,transformer oil aging
更新于2025-09-10 09:29:36
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Aging spectral markers of tequila observed by Raman spectroscopy
摘要： In this work, were studied the aging spectral markers of three types of tequila: Blanco, Reposado, and A?ejo (white, rested, and aged, respectively) by Raman spectroscopy with the aim of qualitatively assessing the aging state of tequilas. The samples were elaborated in the same distillery to increase the correctness of the analysis since the contribution of manufacturing process factors, e.g., the type of water used for the elaboration, the origin of raw materials like agaves, sugar, barrels, and others would be similar for all the kinds of tequila. It was demonstrated that complementary information can be obtained through the employment of two excitation wavelengths: 532 and 785 nm. Fluorescence intensity increases with the aging degree of the tequilas as observed with the 532 nm line providing qualitative information about the resting time within the barrels. Additionally, by employing the 785 nm line it was possible to discern through the νs-CCO νa-CCO bands, (C–O) and (C–H) stretching modes and CH2 wagging bonds, the aging spectral markers of tequila.
关键词： Tequila,Raman spectroscopy,Beverage maturation,Cask aging
更新于2025-09-10 09:29:36
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Application of polybenzimidazole as a panchromatic ultraviolet absorber in poly(vinyl chloride) film
摘要： The exposure of poly(vinyl chloride) (PVC) materials to ultraviolet (UV) light can result in the destruction of the molecular structure and consequently a reduction of their mechanical properties. In this study, polybenzimidazole (OPBI) with panchromatic UV absorption was prepared by solution polycondensation and then used as a light stabilizer to improve the UV-resistance properties of PVC. PVC/OPBI composite films with different compositions were prepared by solution casting method, and the effects of OPBI content and UV irradiation time on the properties of these films were investigated by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, dynamic mechanical analysis and tensile test. The results show that OPBI has excellent UV absorption properties in the region of 220–420 nm and high thermal stability with a 3.0% weight loss at 550 °C in nitrogen atmosphere. The PVC/OPBI composite films also show excellent mechanical properties with a yield strength of 46.1–53.4 MPa, which can be attributed to the strong interactions among benzene rings, heterocyclic imidazole and chlorine atoms between OPBI and PVC. The special conjugated structure of OPBI allows the PVC/OPBI composite films to have high UV absorption and excellent mechanical properties, thus making it a promising light stabilizer.
关键词： Ultraviolet resistance,Polybenzimidazole,Light stabilizer,Poly(vinyl chloride),Accelerated ultraviolet aging
更新于2025-09-10 09:29:36