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Transient thermal analysis as measurement method for IC package structural integrity

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Chinese Physics B 2015年第6期24卷 47-64页

作者： Alexander Han Maximilian Schmid E Liu Gordon Elger technische hochschule Ingolstadt

Practices of IC package reliability testing are reviewed briefly, and the application of transient thermal analysis is examined in great depth. For the design of light sources based on light emitting diode （LED） efficient and accurate reliability testing is required to realize the potential lifetimes of 105 h. Transient thermal analysis is a standard method to determine the transient thermal impedance of semiconductor devices, e.g. power electronics and LEDs. The temperature of the semiconductor junctions is assessed by time-resolved measurement of their forward voltage （Vf）. The thermal path in the IC package is resolved by the transient technique in the time domain. This enables analyzing the structural integrity of the semiconductor package. However, to evaluate thermal resistance, one must also measure the dissipated energy of the device （i.e., the thermal load） and the k-factor. This is time consuming, and measurement errors reduce the accuracy. To overcome these limitations, an innovative approach, the relative thermal resistance method, was developed to reduce the measurement effort, increase accuracy and enable automatic data evaluation. This new way of evaluating data simplifies the thermal transient analysis by eliminating measurement of the k-factor and thermal load, i.e. measurement of the lumen flux for LEDs, by normalizing the transient Vf data. This is especially advantageous for reliability testing where changes in the thermal path, like cracks and delaminations, can be determined without measuring the k-factor and thermal load. Different failure modes can be separated in the time domain. The sensitivity of the method is demonstrated by its application to high- power white InGaN LEDs. For detailed analysis and identification of the failure mode of the LED packages, the transient signals are simulated by time-resolved finite element （FE） simulations. Using the new approach, the transient thermal analysis is enhanced to a powerful tool for reliability

关键词： transient thermal analysis thermal resistance reliability light emitting diode

Towards a versatile point-of-care systemcombining femtosecond laser generatedmicrofluidic channels and direct laserwritten microneedle arrays

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Microsystems & Nanoengineering 2019年第1期5卷 606-614页

作者： Anika Trautmann Gian-Luca Roth Benedikt Nujiqi Thomas Walther Ralf Hellmann Applied Laser and Photonics Group University of Applied Sciences AschaffenburgWuerzburger Strasse 4563743 AschaffenburgGermany Institute of Applied Physics Technische Universität DarmstadtSchlossgartenstrasse 764289 DarmstadtGermany

Microneedle-based microfluidic systems have a great potential to become well-accepted medical devices for simple,accurate,and painless drug delivery and lab-on-a-chip *** this work,we report on a novel hybrid approach combining femtosecond direct laser written microneedles with femtosecond laser generated microfluidic channels providing an important step towards versatile medical point-of-care *** microneedle arrays are fabricated by a laser system designed for two-photon polymerization *** tests of two different types of truncated cone-shaped microneedle arrays prepared from OrmoComp^(■)give information about the microneedle mechanical strength,and the results are compared to skin insertion ***-dimensional microchannels are directly created inside PMMA bulk material by an ultrashort pulse laser system with vertical channels having adjustable cross-sectional areas,which allow attaching of microneedles to the microfluidic system.A comprehensive parameter study varying pulse duration and repetition rate is performed on two-photon polymerization to identify an optimal laser power range for fabricating microneedles using the same pulse duration and repetition rate as for *** addresses the advantage of a single laser system process that overcomes complex fabrication methods.A proof of concept flow test with a rhodamine B dye solution in distilled water demonstrates that the combination of microneedles and microchannels qualifies for microfluidic injection and extraction applications.

关键词： arrays versatile needle

Efficient Noninvasive FHB Estimation using RGB Images from a Novel Multiyear,Multirater Dataset

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Plant Phenomics 2023年第3期5卷 533-545页

作者： DominikRößle LukasPrey LudwigRamgraber AnjaHanemann DanielCremers Patrick OleNoack TorstenSchön AImotion Bavaria Technische Hochschule IngolstadtIngolstadtGermany hochschule Weihenstephan-Triesdorf WeidenbachGermany Saatzucht Josef Breun GmbH and Co.KG HerzogenaurachGermany Technical University of Munich MunichGermany

Fusarium head blight(FHB)is one of the most prevalent wheat diseases,causing substantial yield losses and health *** phenotyping of FHB is crucial for accelerating resistance breeding,but currently used methods are time-consuming and *** present article suggests a noninvasive classification model for FHB severity estimation using red–green–blue(RGB)images,without requiring extensive *** model accepts images taken from consumer-grade,low-cost RGB cameras and classifies the FHB severity into 6 ordinal *** addition,we introduce a novel dataset consisting of around 3,000 images from 3 different years(2020,2021,and 2022)and 2 FHB severity assessments per image from independent *** used a pretrained EfficientNet(size b0),redesigned as a regression *** results demonstrate that the interrater reliability(Cohen’s kappa,κ)is substantially lower than the achieved individual network-to-rater results,e.g.,0.68 and 0.76 for the data captured in 2020,*** model shows a generalization effect when trained with data from multiple years and tested on data from an independent ***,using the images from 2020 and 2021 for training and 2022 for testing,we improved the F_(1)^(w) score by 0.14,the accuracy by 0.11,κ by 0.12,and reduced the root mean squared error by 0.5 compared to the best network trained only on a single year’s *** proposed lightweight model and methods could be deployed on mobile devices to automatically and objectively assess FHB severity with images from low-cost RGB *** source code and the dataset are available at https://***/cvims/FHB_classification.

关键词： network consuming breeding

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

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Friction 2021年第3期9卷 583-597页

作者： Florian KÖNIG Christopher SOUS Georg JACOBS Institute for Machine Elements and Systems Engineering Rheinisch-Westfälische Technische Hochschule Aachen UniversitySchinkelstraße 10Aachen 52062Germany

With the increased use of automotive engine start-stop systems,the numerical prediction and reduction of frictional losses in sliding bearings during starting and stopping procedures has become an important *** engineering practice,numerical simulations of sliding bearings in automotive engines are performed with statistical asperity contact models with empirical values for the necessary surface *** aim of this study is to elucidate the applicability of these approaches for the prediction of friction in sliding bearings subjected to start-stop *** this purpose,the friction performance of sliding bearings was investigated in experiments on a test rig and in transient mixed elasto-hydrodynamic simulations in a multi-body simulation environment(mixed-EHL/MBS).In mixed-EHL/MBS,the extended Reynold’s equation with flow factors according to Patir and Cheng has been combined on the one hand with the statistical asperity contact model according to Greenwood and Tripp and on the other hand with the deterministic asperity contact model according to *** detailed comparison of simulation and experimental results clarifies that the application of statistical asperity contact models with empirical values of the necessary inputs leads to large deviations between experiment and *** actual distribution and position of surface roughness,as used in deterministic contact modelling,is necessary for a reliable prediction of the frictional losses in sliding bearings during start-stop operation.

关键词： sliding bearing friction wearing-in contact model,mixed elasto-hydrodynamic simulation

Discussions on the correspondence of dissipative particle dynamics and Langevin dynamics at small scales

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Applied Mathematics and Mechanics(English Edition) 2018年第1期39卷 31-46页

作者： D. AZARNYKH S. LITVINOV X. BIAN N.A. ADAMS Department of Mechanical Engineering Technical University of Munich Munchen 85748 Germany Eidgen Sssische technische hochschule Zfirich Zurich CH-8092 Switzerland

We investigate the behavior of dissipative particle dynamics （DPD） within different scaling regimes by numerical simulations. The paper extends earlier analytical findings of Ripoll, M., Ernst, M. H., and Espafiol, P. （Large scale and mesoscopic hy- drodynamics for dissipative particle dynamics. Journal of Chemical Physics, 115（15）, 7271-7281 （2001）） by evaluation of numerical data for the particle and collective scaling regimes and the four different subregimes. DPD simulations are performed for a range of dynamic overlapping parameters. Based on analyses of the current auto-correlation functions （CACFs）, we demonstrate that within the particle regime at scales smaller than its force cut-off radius, DPD follows Langevin dynamics. For the collective regime, we show that the small-scale behavior of DPD differs from Langevin dynamics. For the wavenumber-dependent effective shear viscosity, universal scaling regimes are observed in the microscopic and mesoscopic wavenumber ranges over the considered range of dynamic overlapping parameters.

关键词： dissipative particle dynamics (DPD) mesoscopic dynamics fluctuating hydrodynamics

Gut-liver axis improves with meloxicam treatment after cirrhotic liver resection

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World Journal of Gastroenterology 2014年第40期20卷 14841-14854页

作者： Astrit R Hamza Avdyl S Krasniqi Pramod Kadaba Srinivasan Mamdouh Afify Christian Bleilevens Uwe Klinge René H Tolba Institute for Laboratory Animal Science and Experimental Surgery University Hospital Rheinisch-Westf?lische Technische Hochschule Aachen 52074 Aachen Germany Department of AbdominalSurgery University Clinical Center of Kosova Prishtina 10000Kosovo Department of Anesthesiology University Hospital Rheinisch-Westf?lische Technische Hochschule Aachen 52074 Aachen Germany Department of Surgery University Hospital Rheinisch-Westf?lische Technische Hochschule Aachen 52074 Aachen Germany

AIM: To investigate the effect of meloxicam on the gut-liver axis after cirrhotic liver resection.

关键词： Liver cirrhosis Liver resection Gut-liver axis Meloxicam Cyclooxigenase-2 Microcirculation

An IR Study of the Dispersion Stability of Catalyst Powders Dispersed in Solutions of Linear Saturated Polyesters

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Chemical Research in Chinese Universities 1992年第1期8卷 59-63页

作者： Gunter R.Joppien Harald Urban technische hochschule Darmstadt Darmstadt F. R. GermanyTechnische Hochschule Darmstadt Darmstadt F. R. Germany

The conformation of polymers at the solid-liquid interface has been the subject of considerable interest in the fundamental theory and applied practice. In paints and printing inks, dispersions of pigment or filler powders in polymeric binder solutions have to be maintained in the colloidal state. One of the stabilizing mechanisms for paint is the steric stabilization. On the other hand, in the formation reaction of polymer at the solid-liquid interface took place between monomer solutions and solid

关键词： Infrared spectrum Dispersion stability Polyester Catalyst

GAMMA－MINIMAX　ESTIMATORS　FOR　THE　MEAN　OF　A　MULTIVARIATE　NORMAL　DISTRIBUTION　WITH　PARTIALLY　UNKNOWN　COVARIANCE　MATRIX

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Acta Mathematicae Applicatae Sinica 1995年第1期11卷 11-16页

作者：陈兰祥 Department of Mathematics Tongji University Shanghai China Fachbereich Mathematik technische hochschule Darmstadt Germany

In this paper Γ-minimax estimation of a multivariate normal mean under arbitrary squared error loss is considered where the covariance matrix of the normal distribution is a known symmetric and positive definite matrix with unknown multiple. The set F is fixed by imposing restrictions on the vector of first moments and on the matrix of second moments as well as on the first moment of the unknown factor determining of the covariance matrix. Necessary and sufficient conditions are derived which ensure that an estimator is Γ-minimax and that a prior is least favorable in Γ.

关键词： Bayes estimation minimax estimation

The Neglected Role of Risk Mitigation Perception in the Risk Governance of Underground Technologies——The Example of Induced Seismicity

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International Journal of Disaster Risk Science 2020年第5期11卷 630-639页

作者： Lisa Haemmerli Michael Stauffacher D-USYS Transdisciplinarity Lab Department of Environmental Systems Science(D-USYS)ETH Zurich(Swiss Federal Institute of Technology/Eidgenossische Technische Hochschule)8092 ZurichSwitzerland

Subsurface technologies,such as geothermal energy and carbon capture and storage,are options to help limit global *** tech no logies involve the risk of induced *** successful implementation of these technologies depends on the public perception of these *** governance frameworks propose assessing the level of public concern and designing adapted risk mitigation *** propose that concerns should not only be investigated with respect to the perceived risks but also with respect to the potential mitigation *** explore this by analyzing the perception of risk mitigation measures for different subsurface *** an online survey(N=808)in Switzerland we analyzed four technologies(in-between subject design)and four mitigation measures(within subject design).We found that risk mitigation measures are perceived differently,within and across ***,public concerns about risk mitigation really *** suggest that future research should focus on how risk mitigation measures can be applied and communicated to realize the full potential of risk governance frameworks.

关键词： Carbon capture and storage Enhanced geothermal systems Induced seismicity Risk mitigation perception Shale gas Switzerland