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- 2017
- spectral reconstruction
- interference
- polarization
- transform
- imaging spectrometer
- Optoelectronic Information Science and Engineering
- BITTT
- Zhejiang University
- Guilin University of Aerospace Technology
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Hardening Effects of In-Situ Aging for a Laser Welded Maraging Steel
摘要： Maraging steels are ultra-high strength alloys which have been successfully laser welded to obtain structural components. For most of the applications these steels are in an aged state to attain tensile strength up to 1.5 GPa, although welding induces local softening due to dissolution of precipitates. This paper aims to investigate the effect of in-situ aging of the maraging steel plates after laser welding to reduce the local softening. For a preheating at 40°C, just below the martensite finish line, the hardness of the Fusion Zone (FZ) attained between 440 and 490 HV and the Heat-Affected Zone (HAZ) attained a maximum of 570 HV compared to 300 HV of the Base Material (BM) for aging temperatures between 450°C and 520°C and periods between 10 and 30 min. The intercritical aging (570°C/1 h) also promoted an increase in local hardness of FZ 320 HV and HAZ 400 HV. Using an intercritical aging, the hardness situated between room temperature and quenched and aged coupons and was more homogeneous considering FZ, HAZ and BM. The microstructure of the intercritical aged welds is marked by duplex-ferrite and martensite micro-constituents.
关键词： Aging,Post-Welding Heat Treatment,Maraging Steels,Laser Beam Welding
更新于2025-09-19 17:13:59
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Effect of laser texturing on the surface characteristics and bonding property of 30CrMnSiA steel adhesive joints
摘要： The influence of laser texturing on the bonding property of 30CrMnSiA steel joints were investigated. Three patterns including dimple, groove and grid were laser textured on the 30CrMnSiA steel substrate by nanosecond fiber laser. The processed surface was characterized by surface morphology, surface roughness (Ra and Rz) and wettability. The single lap adhesive joints were fabricated and fracture surfaces were observed. The accelerated hygrothermal aging experiments were performed. The results indicated that surface roughness and wettability were both enhanced after laser texturing. The grid patterned substrate was improved pronouncedly, where Ra increased by 400% and Rz was 13 times higher than as-received specimens, and the contact angle was decreased from 65° to 24°. The shear strength of adhesive joints for dimple pattern was not improved evidently, while it was 14.6 MPa and 23.3 MPa in the groove and grid patterned specimens, which was increased by 219%, 348% compared to as-received ones, respectively. The coverage of adhesive layer on the fracture surface was increased and the fracture mode of dimple and groove patterned specimens was adhesive failure and a cohesive failure was achieved for those joints with grid pattern. The bonding property was decreased after hygrothermal aging, and the residual strength of specimens with grid pattern was the highest. The fracture mode was not changed in all adhesive joints.
关键词： Laser texturing,Wettability,Roughness,Adhesive strength,Hygrothermal aging
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - UV exposure: a novel processing method to fabricate nanowire solar cells
摘要： This paper presents a physics-based compact modeling approach that incorporates the impact of total ionizing dose (TID) and stress-induced defects into simulations of metal-oxide-semiconductor (MOS) devices and integrated circuits (ICs). This approach utilizes calculations of surface potential (ψs) to capture the charge contribution from oxide trapped charge and interface traps and to describe their impact on MOS electrostatics and device operating characteristics as a function of ionizing radiation exposure and aging effects. The modeling approach is demonstrated for bulk and silicon-on-insulator (SOI) MOS device. The formulation is verified using TCAD simulations and through the comparison of model calculations and experimental I-V characteristics from irradiated devices. The modeling approach is suitable for simulating TID and aging effects in advanced MOS devices and ICs, and is compatible with modern MOSFET compact modeling techniques. A circuit-level demonstration is given for TID and aging effects in SRAM cells.
关键词： MOSFET,SOI,semiconductor devices,compact modeling,ionizing radiation,Aging effects
更新于2025-09-19 17:13:59
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[IEEE IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Lisbon, Portugal (2019.10.14-2019.10.17)] IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Techno-Economic Analysis of Building Integrated Photovoltaics Electrical Installations
摘要： Insulated-gate bipolar transistor (IGBT) power modules find widespread use in numerous power conversion applications where their reliability is of significant concern. Standard IGBT modules are fabricated for general-purpose applications while little has been designed for bespoke applications. However, conventional design of IGBTs can be improved by the multiobjective optimization technique. This paper proposes a novel design method to consider die-attachment solder failures induced by short power cycling and baseplate solder fatigue induced by the thermal cycling which are among major failure mechanisms of IGBTs. Thermal resistance is calculated analytically and the plastic work design is obtained with a high-fidelity finite-element model, which has been validated experimentally. The objective of minimizing the plastic work and constrain functions is formulated by the surrogate model. The nondominated sorting genetic algorithm-II is used to search for the Pareto-optimal solutions and the best design. The result of this combination generates an effective approach to optimize the physical structure of power electronic modules, taking account of historical environmental and operational conditions in the field.
关键词： power cycling (PC),Aging,fatigue,insulated-gate bipolar transistors (IGBTs),thermal cycling (TC),multiobjective,optimization methods,reliability,finite-element (FE) methods
更新于2025-09-19 17:13:59
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Quantitative spatially resolved <i>post-mortem</i> analysis of lithium distribution and transition metal depositions on cycled electrodes <i>via</i> a laser ablation-inductively coupled plasma-optical emission spectrometry method
摘要： Diminishing the loss of performance of lithium ion batteries (LIBs) is a challenge that is yet to be ful?lled. Understanding of deterioration processes and mechanisms (i.e., so-called aging) requires analytically accurate examination of aged cells. Changes in the distribution of lithium or transition metals in the LIB cells can in?uence their cycle and calendar life signi?cantly. As electrochemically treated cells and especially their electrodes do not age homogeneously and the local electrochemistry (e.g. deposition patterns) is strongly dependent on surface properties, bulk analysis is not a satisfactory investigation method. Therefore, a surface sensitive method, namely laser ablation-inductively coupled plasma-optical emission spectrometry (LA-ICP-OES) is presented. LIB cells with lithium metal oxide LiNi1/3Co1/3Mn1/3O2 (NCM111) as cathode material and graphite as anode material are investigated using a 213 nm Nd:YAG laser.
关键词： graphite,aging,laser ablation-inductively coupled plasma-optical emission spectrometry,NCM111,LA-ICP-OES,LIBs,Nd:YAG laser,lithium ion batteries
更新于2025-09-19 17:13:59
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Investigation of polymera??based composites by laser desorption ionization Study of their photoa??oxidative aging
摘要： RATIONALE The polybutadiene (PB) is one of the most widely used polymers. Its aging occurs by reaction with oxygen under illumination and may modify its mechanical and/or aesthetic properties. To modify its properties, organic and/or inorganic compounds are generally added to the PB. The aging of such composite materials is poorly known. METHODS The PB and its mixtures with TiO2 and/or the Orange 13 pigment are subjected to an accelerated photo-oxidative aging step for one week. The analysis of PB and its composites with regard to their composition and the aging time, is carried out by 266 nm and/or 355 nm laser/desorption ionization Fourier transform ion cyclotron resonance mass spectrometry (LDI FT ICR–MS). RESULTS Both PB and its degradation products are detected by (+) LDI FT–ICR MS. The oxidation mechanism of the PB is not significantly affected by the used organic or inorganic fillers, which results from the cleavage of the polymer chain and the formation of carbonyl compounds. The crosslinking of the PB is significantly reduced by the two investigated fillers. The (–) LDI FT–ICR MS ensure the specific detection of the Orange 13 pigment. CONCLUSIONS LDI FT ICR - MS has demonstrated its ability to provide relevant information on the degradation of polymer-based composites. The main advantages of this approach are its ability to probe the surface, which is specifically affected by photo-oxidation aging processes, and to access the insoluble degradation compounds.
关键词： Orange 13 pigment,titanium dioxide,photo-aging,Polybutadiene
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Parallel Computation Technology for Distributed Optical Fiber Sensing System
摘要： The gradual changes that occur in the human voice due to aging create challenges for speaker verification. This study presents an approach to calibrating the output scores of a speaker verification system using the time interval between comparison samples as additional information. Several functions are proposed for the incorporation of this time information, which is viewed as aging information, in a conventional linear score calibration transformation. Experiments are presented on data with short-term aging intervals ranging between 2 months and 3 years, and long-term aging intervals of up to 30 years. The aging calibration proposal is shown to offset the decreased discrimination and calibration performance for both short- and long-term intervals, and to extrapolate well to unseen aging intervals. Relative reductions in C(cid:2)(cid:2)r (cost of log-likelihood ratio) of 1–4% and 10–43% are obtained at short- and long-term intervals, respectively. Assuming that a system has knowledge of the time interval between samples under comparison, this approach represents a straightforward means of compensating for the detrimental impact of aging on speaker verification performance.
关键词： speaker variability,quality measures,Aging,calibration,speaker verification
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - a-Si:H/c-Si interface hydrogenation for implied V <sub/>oc</sub> = 755 mV in Silicon heterojunction solar cell
摘要： Insulated-gate bipolar transistor (IGBT) power modules find widespread use in numerous power conversion applications where their reliability is of significant concern. Standard IGBT modules are fabricated for general-purpose applications while little has been designed for bespoke applications. However, conventional design of IGBTs can be improved by the multiobjective optimization technique. This paper proposes a novel design method to consider die-attachment solder failures induced by short power cycling and baseplate solder fatigue induced by the thermal cycling which are among major failure mechanisms of IGBTs. Thermal resistance is calculated analytically and the plastic work design is obtained with a high-fidelity finite-element model, which has been validated experimentally. The objective of minimizing the plastic work and constrain functions is formulated by the surrogate model. The nondominated sorting genetic algorithm-II is used to search for the Pareto-optimal solutions and the best design. The result of this combination generates an effective approach to optimize the physical structure of power electronic modules, taking account of historical environmental and operational conditions in the field.
关键词： fatigue,power cycling (PC),insulated-gate bipolar transistors (IGBTs),thermal cycling (TC),reliability,optimization methods,finite-element (FE) methods,Aging,multiobjective
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - GaSb Solar Cells Grown by MOCVD via IMF on GaAs
摘要： An aging and more sedentary population requires interventions aimed at monitoring physical activity, particularly within the home. This research uses simulation, optimization, and regression analyses to assess the feasibility of using a small number of sensors to track movement and infer physical activity levels of older adults. Based on activity data from the American Time Use Survey and assisted living apartment layouts, we determined that using three to four doorway sensors can be used to effectively capture a suf?cient amount of movements in order to estimate activity. The research also identi?ed preferred approaches for assigning sensor locations, evaluated the error magnitude inherent in the approach, and developed a methodology to identify which apartment layouts would be best suited for these technologies.
关键词： successful aging,gerontology,smart homes,Biomedical monitoring,sensors,senior citizens,geriatrics
更新于2025-09-19 17:13:59
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Use of the inferior whorl to detecting age-related changes in human corneal subbasal nerve plexus with laser-scanning confocal microscopy
摘要： Purpose: To determine the effect of aging on the corneal subbasal nerve plexus (SNP) by employing a wide-field mapping technique of composite images, scanned at the location of a distinctive spiraled subbasal nerve pattern located 1 to 2 mm inferior to the corneal apex (the inferior whorl) for SNP structural quantification. Material and methods: The central corneal tactile sensitivity (CCTS) and inferior whorl length (IWL) were compared among individuals in three age groups (20–39 years, 40–59 years, and 60–79 years). Statistical analyses constituted the Kruskal-Wallis test, one-way analysis of variance (with post hoc least significant difference test), Spearman correlation coefficient, and linear regression. Results: CCTS remained stable until the age of 50 years, when it began to decrease; the mean CCTS was 58.15±2.46 mm in the group aged 20–39, 55.74±3.85 mm in the group aged 40–59, and 50.23±3.27 mm in the group aged 60–79. IWL decreased with increasing age, with a corresponding linear decline of 0.2088 mm/mm2 per year, and the mean IWL was 25.43±4.50 mm/mm2 in the group aged 20–39, 22.71±6.19 mm/mm2 in the group aged 40–59, and 18.60±4.21 mm/mm2 in the group aged 60–79. Conclusion: Our work provided a more accurate and repeatable method for corneal nerve analysis using Laser-Scanning Confocal Microscopy (LSCM). By using this technique, we confirmed that aging is associated with progressive reduction in subbasal nerve length.
关键词： aging,subbasal nerve plexus,laser-scanning confocal microscopy,inferior whorl
更新于2025-09-19 17:13:59