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[IEEE 2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Stockholm, Sweden (2018.9.26-2018.9.28)] 2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Structural analysis and modelling of packaged light emitting devices by thermal transient measurements at multiple boundaries
摘要： The paper presents a comprehensive methodology for modeling the electrical, optical, and thermal domains of high-power LEDs, focusing on the XPE2 type from Cree. It introduces optimization algorithms (OPT1 and OPT2) to extract parameters such as series resistance (RS), ideality factor (m), and saturation current (I0) from forward voltage (VF) measurements. A quadratic model for radiant voltage (Vrad) is developed to describe the optical output, and thermal modeling is addressed through structure functions derived from transient thermal measurements. The approach enables accurate prediction of LED performance across varying currents and temperatures, with applications in thermal management and design optimization.
关键词： ideality factor,thermal management,structure function,LED modeling,radiant flux,forward voltage,saturation current,series resistance
更新于2025-09-23 15:23:52
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Enhanced Structure-Function Relationship in Glaucoma With an Anatomically and Geometrically Accurate Neuroretinal Rim Measurement
摘要： PURPOSE. To evaluate the structure–function relationship between disc margin–based rim area (DM-RA) obtained with confocal scanning laser tomography (CSLT), Bruch’s membrane opening–based horizontal rim width (BMO-HRW), minimum rim width (BMO-MRW), peripapillary retinal nerve fiber layer thickness (RNFLT) obtained with spectral-domain optical coherence tomography (SD-OCT), and visual field sensitivity. METHODS. We examined 151 glaucoma patients with CSLT, SD-OCT, and standard automated perimetry on the same day. Optic nerve head (ONH) and RNFL with SD-OCT were acquired relative to a fixed coordinate system (acquired image frame [AIF]) and to the eye-specific fovea-BMO center (FoBMO) axis. Visual field locations were mapped to ONH and RNFL sectors with fixed Garway-Heath (VFGH) and patient-specific (VFPS) maps customized for various biometric parameters. RESULTS. Globally and sectorally, the structure–function relationships between DM-RA and VFGH, BMO-HRWAIF and VFGH, and BMO-HRWFoBMO and VFPS were equally weak. The R2 for the relationship between DM-RA and VFGH ranged from 0.1% (inferonasal) to 11% (superotemporal) whereas that between BMO-HRWAIF and VFGH ranged from 0.1% (nasal) to 10% (superotemporal). Relatively stronger global and sectoral structure–function relationships with BMO-MRWAIF and with BMO-MRWFoBMO were obtained. The R2 between BMO-MRWAIF and VFGH ranged from 5% (nasal) to 30% (superotemporal), whereas that between BMO-MRWFoBMO and VFPS ranged from 5% (nasal) to 25% (inferotemporal). The structure–function relationship with RNFLT was not significantly different from that with BMO-MRW, regardless of image acquisition method. CONCLUSIONS. The structure–function relationship was enhanced with BMO-MRW compared with the other neuroretinal rim measurements, due mainly to its geometrically accurate properties.
关键词： glaucoma,structure–function relationship,visual field,optic nerve head,automated perimetry
更新于2025-09-23 15:21:01
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Deep inelastic scattering on a nucleus using holography
摘要： We consider deep inelastic scattering (DIS) on a nucleus described using a density expansion. In leading order, the scattering is dominated by the incoherent scattering on individual nucleons distributed using the Thomas-Fermi approximation. We use the holographic structure functions for DIS scattering on single nucleons to make a nonperturbative estimate of the nuclear structure function in leading order in the density. Our results are compared to the fits from data in the large-x regime.
关键词： Thomas-Fermi approximation,deep inelastic scattering,nuclear structure function,holography,nucleus
更新于2025-09-23 15:19:57
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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) - Calculation of the optical losses in perovskite solar cells
摘要： Terminal network reliability problems appear in many real-life applications, such as transportation grids, social and computer networks, communication systems, etc. In this paper, we focus on monotone binary systems with identical component reliabilities. The reliability of such systems depends only on the number of failure sets of all possible sizes, which is an essential system invariant. For large problems, no analytical solution for calculating this invariant in a reasonable time is known to exist, and one has to rely on different approximation techniques. An example of such a method is Permutation Monte Carlo. It is known that this simple plan is not sufficient for adequate estimation of network reliability due to the rare-event problem. As an alternative, we propose a different sampling strategy that is based on the recently pioneered Stochastic Enumeration algorithm for tree cost estimation. We show that, thanks to its built-in splitting mechanism, this method is able to deliver accurate results while employing a relatively modest sample size. Moreover, our numerical results indicate that the proposed sampling scheme is capable of solving problems that are far beyond the reach of the simple Permutation Monte Carlo approach.
关键词： System structure function,splitting,network reliability,rare events,stochastic enumeration,permutation Monte Carlo
更新于2025-09-19 17:13:59
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Thermal analysis and heat dissipation improvement for quantum cascade lasers through experiments, simulations, and structure function
摘要： We quantified the thermal resistance of quantum cascade lasers (QCLs) using their structure functions and increased the laser output by employing ridge structures in which thermal resistance was reduced. To improve heat properties, three different QCL devices were prepared as follows. One was a device whose ridge was covered with SiO2, another was a device whose ridge was embedded with Au, and the other was a device whose ridge was embedded with Cu. The temperature distributions were measured with a thermoviewer and were analyzed with three-dimensional simulations. From the results, improved heat dissipation by embedding the ridge was clarified. Furthermore, the structure functions obtained by static mode measurement suggested that the thermal resistance was improved from 9.3 to 6.5 K W?1 by embedding the ridge. As a result of the improvement, the QCL with the Au-embedded ridge had a 1.5-fold higher laser power than the QCL with the SiO2-covered ridge.
关键词： thermal resistance,laser output,heat dissipation,structure function,quantum cascade lasers
更新于2025-09-19 17:13:59
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Structure–Function Relationship in Glaucoma Using Ganglion Cell–Inner Plexiform Layer Thickness Measurements
摘要： PURPOSE. To evaluate the structure–function relationship between ganglion cell–inner plexiform layer (GCIPL) thickness at the macula and 10-2 standard automated perimetry (SAP) in glaucoma and to evaluate the relationship using a recently proposed linear model. METHODS. In a cross-sectional analysis, structure–function relationship was determined in 50 glaucomatous eyes (40 patients, mean deviation: (cid:2)15.4 6 7.5 dB) and 21 control eyes (13 subjects, mean deviation: (cid:2)3.4 6 3.0 dB), which had undergone 10-2 SAP and GCIPL imaging on the same day. Functional loss was derived from total deviation numerical values on 10-2 SAP and calculated on both a linear (reciprocal of Lambert) and a decibel scale after accounting for the retinal ganglion cell displacement at the macula. Strength of relationship was reported as coef?cient of determination (R2) of the linear regression models ?tted to the data separately for different sectors. The relationship was also evaluated using a linear model. RESULTS. The R2 for the associations between GCIPL thickness sectors and the corresponding sector SAP total deviation values ranged from 0.19 (for superonasal GCIPL sector) to 0.60 (for average GCIPL thickness) when functional loss was calculated on the decibel scale and 0.16 (for superonasal sector) to 0.54 (for inferior sector) on the linear scale. All associations were statistically signi?cant (P < 0.05). The linear model ?tted the data reasonably well. CONCLUSIONS. Signi?cant structure–function associations were found between GCIPL thickness measurements at the macula and the functional loss measured on 10-2 SAP in glaucoma. Best ?t was found for the inferior and average GCIPL sector thickness. The linear model was useful to study the structure–function relationship.
关键词： visual ?eld,ganglion cell–inner plexiform layer,glaucoma,structure–function relationship
更新于2025-09-11 14:15:04
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Evaluation of Structure-Function Relationships in Longitudinal Changes of Glaucoma using the Spectralis OCT Follow-Up Mode
摘要： The detection of glaucoma progression is an essential part of glaucoma management. Subjectivity of standard automated perimetry (SAP) prevents the accurate evaluation of progression, thus the detection of structural changes by optical coherence tomography (OCT) is attracting attention. Despite its objectivity, there is controversy about the appropriateness of the use of OCT, because many previous studies have indicated OCT results may not reflect the deterioration of visual field. A reason for this dissociation may be the test-retest variability of OCT, a major cause of which is misplacement of the measurement location. Recent advantages of spectral-domain OCT (SD-OCT), especially Spectralis OCT with an eye-tracking system (follow-up mode) enable measurement at approximately the same location as previous examinations. In addition to utilizing Spectralis follow-up mode, we introduced structure-function relationship map and nonlinear relationship between SAP and OCT results in considering structure-function relationship in longitudinal changes. The introduction of these two ideas in our study population improved the correlation between the SAP and OCT (R = 0.589 at most). The results of this study support the practical use of OCT in glaucoma progression but also stress the importance of focus on the corresponding focal changes and the consideration of disease severity.
关键词： longitudinal study,standard automated perimetry,optical coherence tomography,structure-function relationship,glaucoma progression
更新于2025-09-10 09:29:36
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Theoretical study of charge-transport and optical properties of indeno[1,2- <i>b</i> ]fluorene-6,12-dione-based semiconducting materials
摘要： The conducting and optical properties of a series of indeno[1,2-b]fluorene-6,12-dione (IFD)-based molecules have been systematically studied and the influences of butyl, butylthio and dibutylamino substituents on the reorganization energies, intermolecular electronic couplings and charge-injection barriers of IFD have been discussed. The quantum-chemical calculations combined with electron-transfer theory reveal that the incorporation of sulfur-linked side chains decreases reorganization energy associated with hole transfer and optimizes intermolecular π–π stacking, which results in excellent ambipolar charge-transport properties (μh = 1.15 cm2 V?1 s?1 and μe = 0.08 cm2 V?1 s?1); in comparison, addition of dibutylamino side chains increases intermolecular steric interactions and hinders perfect intermolecular π–π stacking, which results in the weak electronic couplings and finally causes the low intrinsic hole mobility (μh = 0.01 cm2 V?1 s?1). Furthermore, electronic spectra of butyl-IFD, butylthio-IFD and dibutylamino-IFD were simulated and compared with the reported experimental data. Calculations demonstrate that IFD-based molecules possess potential for developing novel infrared and near-infrared probe materials via suitable chemical modifications.
关键词： intrinsic electron mobility,structure–function relationship,indeno[1,2-b]fluorene-6,12-dione-based molecules,density functional theory (DFT),intrinsic hole mobility,electronic spectra
更新于2025-09-09 09:28:46
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Understanding macroscale functionality of metal halide perovskites in terms of nanoscale heterogeneities
摘要： Hybrid metal halide perovskites have shown an unprecedented rise as semiconductor building blocks for solar energy conversion and light-emitting applications. Currently, the field moves empirically towards more and more complex chemical compositions, including mixed halide quadruple cation compounds that allow optical properties to be tuned and show promise for better stability. Despite tremendous progress in the field, there is a need for better understanding of mechanisms of efficiency loss and instabilities to facilitate rational optimization of composition. Starting from the device level and then diving into nanoscale properties, we highlight how structural and compositional heterogeneities affect macroscopic optoelectronic characteristics. Furthermore, we provide an overview of some of the advanced spectroscopy and imaging methods that are used to probe disorder and non-uniformities. A unique feature of hybrid halide perovskite compounds is the propensity for these heterogeneities to evolve in space and time under relatively mild illumination and applied electric fields, such as those found within active devices. This introduces an additional challenge for characterization and calls for application of complimentary probes that can aid in correlating the properties of local disorder with macroscopic function, with the ultimate goal of rationally tailoring synthesis towards optimal structures and compositions.
关键词： halide perovskites,structure-function relationship,nanoscale heterogeneities,recombination
更新于2025-09-09 09:28:46