bluuebunny/crossref_metadata_2025_split huggingface dataset:
Robust Data Acquisition for Building Lighting Systems
Authors: Pearson Zak , Crenshaw Tanya L. , Dillon Heather , Paulson Erik , Warlen Nick 
Published: November 2015

In 2012, 12% of US electricity consumption was due to residential and commercial lighting. By 2030, LED lightbulbs will be more plentiful, projected to drive a 40% reduction in energy [1]. Yet today’s LED lightbulbs have bulky heat sinks that do not leverage modern thermal management techniques. Reducing the size of the heat sink offers lower cost and increased energy efficiency.
To leverage modern techniques, it is valuable to understand how thermal performance degrades light quality as people utilize lights over weeks and months. However, using current data acquisition systems to obtain such massive data sets is expensive, time-consuming, and cable-ridden.
We have developed a robust ground-to-cloud system to acquire temperature and luminosity data for building lighting systems. The data acquisition units are small and may be positioned in existing lighting installations. During acquisition, data is backed up automatically. Usability studies demonstrate that novice users can configure an experiment in less than four minutes.
A Compliance-Based Approach to Study Fatigue Crack Propagation for a Copper-Epoxy Interface
Authors: Samet David , Kwatra Abhishek , Sitaraman Suresh K. 
Published: November 2015

As the microelectronics industry continues to advance the boundaries of size and performance, focus on the impact of systems packaging has risen to the forefront of design and material considerations. As interfaces are often constructed of multiple heterogeneous layers, interfacial delamination is an important failure mechanism to consider in microelectronic packaging. This failure is due to, among other factors, the stresses arising from high mismatches in coefficient of thermal expansion (CTE). Most work to date has focused on interfacial crack propagation under monotonic loading that is incurred during fabrication steps such as deposition or curing which occur at elevated temperatures and subsequent cooling to room temperature. This is an important design consideration but it is not sufficient as the operational life of these devices involve high numbers of heating and cooling cycles which result in crack propagation under fatigue loading. As such the study of fatigue effects on these interfaces is paramount to improving the lifetime of microelectronic devices as the field pushes towards both thinner and wider packages.
One such exploration, which is the subject of this work, is to determine the interface incremental crack growth rate as it relates to cyclic loading. In this work, double cantilever beam (DCB) tests are performed at various stress ratios on samples with epoxy mold compound (EMC) atop a copper leadframe. For these tests, force versus displacement curves will be obtained. Given the small dimensions of the interfaces in question, it is desirable to develop a test methodology that does not require in-situ measurement of crack length. Thus, in these tests the compliance of the samples is determined from the force versus displacement curves and used to infer the progress of the crack through an indirect approach. The advantage of this method is that it does not require the observational measurement of the crack length potentially allowing crack monitoring absent any optical or imaging methods. Using the determined crack propagation rate with fatigue cycle under various loading conditions, a generalized fatigue crack propagation model will be developed for mold compound and copper interface, and such a model can be employed to assess packaging reliability in operating conditions.
Lab-on-a-Chip Device for Hydrogen Sulfide Sensing in Biomedical and Environmental Applications Using Electrochemical Approach
Authors: Baniya A. , Thapa S. , Borquist E. , Bailey D. , Wood D. , Dutta G. , Arumugam P. , Glawe J. , Kevil C. , Weiss L. 
Published: November 2015

Hydrogen sulfide (H2S) is rapidly emerging as a biologically significant signaling molecule. In recent studies, sulfide level in blood or plasma has been reported to be in the concentration between 10 and 300 μM suggesting it acts in various diseases. This work reports progress on a new Lab-on-a-Chip (LOC) device for these applications. The uniquely designed, hand-held device uses advanced liberation chemistry that releases H2S from liquid sample and an electrochemical approach to detect sulfide concentration from the aqueous solution.
The device itself consists of three distinct layers of Polydimethylsiloxane (PDMS) structures and a three electrode system for direct and rapid H2S concentration measurement.
In this work specifically, the oxidation of sulfide at the gold (Au) and platinum (Pt.) electrodes has been examined. This is the first known application of electrochemical H2S sensing in an LOC application. The analytical utility and performance of the device has been assessed through direct detection using chronoamperometry (CA) scan and cyclic voltammetry (CV). An electrocatalytic sulfide oxidation signal has been recorded for sulfide concentration range vs, Ag/AgCl at different pH buffers at the trapping chamber. The calibration curve in the range 1 μM to 1 M was obtained using this electrode setup. The detection limit was found to be 0.1 μM. This device shows promise for providing fast and inexpensive determination of H2S concentration in aqueous samples.
Multi-Physics Driven Co-Design of 3D Multicore Architectures
Authors: Xiao He , Yueh Wen , Mukhopadhyay Saibal , Yalamanchili Sudhakar 
Published: November 2015

The high heat flux and strong thermal coupling in the 3D ICs has limited the performance gains that would otherwise be feasible in 3D structures. The common practice of adopting worst-case design margins is in part responsible for this limitation since average-case performance would be limited by worst-case thermal design margins. The coupling between temperature and leakage power exacerbates this effect. However, worst-case thermal conditions are not the common state across the package at runtime. We argue for the co-design of the package, architecture, and power management based on the multi-physics interactions between temperature, power consumption and system performance. This approach suggests an adaptive architecture that accommodates the thermal coupling between layers and leads to increased energy efficiency over a wider operating voltage range and therefore higher performance.
In this paper, we target at a 3D multicore architecture where the cores reside on one die and the last level cache (LLC) resides on the other. The DRAM stack may be stacked on top of the package (e.g., 3D) or in the same package (e.g., 2.5D). We propose a novel adaptive cache structure — the constant performance model (CPM) cache — based on voltage adaptations to temperature variations. We construct a HSPICE model for the SRAM to explore the relationship between temperature, supply voltage, and the circuit delay in the context of the LLC. This model is used to investigate, characterize, and analyze the effect of the temperature-delay dependence of the SRAM LLC configuration on the system-level performance and energy efficiency. This analysis gives rise to an intelligent scheme for dynamic voltage regulation in the LLC cache that is sensitive to the temperature of the individual cache banks. Each cache bank is thermally coupled to the associated cores and thus is sensitive to the local core-level power management. We show that this local adaptation to the temperature-delay dependence leads to a significant power reduction in the LLC cache, and improvement of system energy efficiency computed as energy per instruction (EPI). We evaluate our approach using a cycle-level, full system simulation model of a 16-core x86 homogenous microarchitecture in 16nm technology that boots a full Linux operating system and executes application binaries. The advantages of the proposed adaptive LLC structure illustrate the potential of the co-design of the package, architecture, and power management in future 3D multicore architectures.
Full Scale Simulation of an Integrated Monolithic Heat Sink for Thermal Management of a High Power Density GaN-SiC Chip
Authors: Liu Tanya , Houshmand Farzad , Gorle Catherine , Scholl Sebastian , Lee Hyoungsoon , Won Yoonjin , Asheghi Mehdi , Goodson Kenneth , Kazemi Hooman , Vanhille Kenneth 
Published: November 2015

Advances in manufacturing techniques are inspiring the design of novel integrated microscale thermal cooling devices seeking to push the limits of current thermal management solutions in high heat flux applications. These advanced cooling technologies can be used to improve the performance of high power density electronics such as GaN-based RF power amplifiers. However, their optimal design requires careful analysis of the combined effects of conduction and convection.
Many numerical simulations and optimization studies have been performed for single cell models of microchannel heat sinks, but these simulations do not provide insight into the flow and heat transfer through the entire device. This study therefore presents the results of conjugate heat transfer CFD simulations for a complex copper monolithic heat sink integrated with a 100 micron thick, 5 mm by 1 mm high power density GaN-SiC chip. The computational model (13 million cells) represents both the chip and the heat sink, which consists of multiple inlets and outlets for fluid entry and exit, delivery and collection manifold systems, and an array of fins that form rectangular microchannels. Total chip powers of up to 150 W at the GaN gates were considered, and a quarter of the device was modeled for total inlet mass flow rates of 1.44 g/s and 1.8 g/s (0.36 g/s and 0.45 g/s for the quarter device), corresponding to laminar flow at Reynolds numbers between 19.5 and 119.3. It was observed that the mass flow rates through individual microchannels in the device vary by up to 45%, depending on the inlet/outlet locations and pressure drop in the manifolds. The results demonstrate that full device simulations provide valuable insight into the multiple parameters that affect cooling performance.
Enhancement of Water Cooling Performance in Narrow Flow Passages by Using Micro Heat Sinks With Miniature Vortex Generators
Authors: Obata Kazuma , Fukue Takashi , Hirose Koichi , Kikuchi Mamoru , Ueda Yasuhiko , Kusabuka Shigekado , Miyahara Tomoyasu 
Published: November 2015

This study describes a possibility of an improvement of water cooling devices for high-power electronic devices such as inverters for electric vehicles by using a combination of micro heat sinks and miniature vortex generators. Power devices such as IGBT (Insulated Gate Bipolar Transistor) are widely used for controlling an operation of electronic vehicles and hybrid vehicles. Due to the improvement of the performance of the power devices, the heat dissipation density from these devices becomes higher. The water cooling is the commonest method for dissipating heat from the inverter of the electronic vehicles. Therefore the improvement of the water cooling technology is significantly needed in order to manage the increase of the heat dissipation density.
We are now trying to develop a high-performance water cooling device for dissipating the high heat flux from the inverters in the electric vehicles by using a combination of a fine miniature heat sink and a miniature vortex generator. The combination of the miniature heat sink and the vortex generator may increase heat transfer performance of the heat exchanger while inhibiting an increase of pressure drop by generating a swirling turbulent flow in a clearance between the heat sink fins. In this study, the water cooling performance in the narrow flow passage, which simulates the flow passage in the water cooling device, with the miniature heat sink and the miniature vortex generators was investigated by using 3-dimentional CFD analysis. From the analysis, we conclude that the combination of the miniature heat sink and the vortex generator was effective for the heat transfer enhancement in the narrow flow passage of the water cooling device while inhibiting the generation of the pressure drop when we can use the combination with the appropriate manner.
Fuming Acid Based Decapsulation Process for Copper-Aluminum Wirebond System Molded With Different EMCs
Authors: Lall Pradeep , Deshpande Shantanu , Nguyen Luu 
Published: November 2015

Decapsulation is one of the very powerful technique in failure analysis process. During this process, die and first level interconnects are exposed by dissolving molding compound around them using variety of methods. Typically decapsulation formulation uses red fuming nitric acid at elevated temperatures. This technique work for traditional Gold wire bonds, but does not work for its new alternative Copper. Gold, being inert metal does not react with acid. Copper on the other hand; tends to react with fuming nitric acid, and dissolves rapidly into acid. It is important to develop acid chemistry that can be successfully used to perform decapsulation of Cu-Al incorporated packages for different EMC’s.
In this paper, decap process based on combination of red fuming nitric acid and concentrated sulfuric acid at elevated temperatures is presented. Reduction in wire diameter was monitored for all devices. For some devices decap process was evaluated based on comparison of WB shear strength of decaped part with unmolded part. SEM was used extensively to track down degradation of copper wires. These tests were performed on packages with different EMC’s, wire diameters, pad thickness and some active dies.
Statistical principal components regression model has been developed correlating the decapsulation process parameters with the post decap wire diameter reduction. Principal component regression in conjunction with stepwise regression has been used to identify the influential variables, and to remove the multicollinearity between the predictor variables. Principal component analysis which combines two correlated variables into a single factor is a widely used image processing technique for pattern recognition and image compression. The post molded packages have then used to assess the effect of various decapsulation treatments.
Creep-Fatigue Crack for a 2¼Cr1Mo and Inconel Transition Weld
Authors: Shi Jinhua 
Published: November 2015

Transition welds have been used in some Advanced Gas-Cooled Reactors to attach a 2¼Cr1Mo spool piece to a hot reheat header, which is fabricated from 316L material. These welds were made using Inconel-82 filler and were post-weld heat-treated (PWHT) at around 705°C. In this paper, a creep-fatigue crack growth assessment has been carried out on the 2¼Cr1Mo ferritic side of the weld using the R5 procedure.
As the welds have been PWHT rather than solution heat treated, therefore there are residual welding stresses present. On the 2¼Cr1Mo ferritic side of the weld, a 60MPa through-wall bending stress has been applied in the axial direction and a 60MPa membrane stress in the hoop direction. These are consistent with the recommendations of R5 Volume 7.
Due to the differing thermal expansion coefficients of Inconel and ferritic materials, thermal mismatch stresses induced from changes in temperatures have been considered. It has been assumed that at the PWHT temperature of 705°C there are no thermal mismatch stresses. Any reduction from this temperature generates thermal mismatch stresses which are accounted for by using secondary Stress Intensification Factor values in the calculation.
On the 2¼Cr1Mo ferritic side of the weld, a 5mm deep by 50mm long circumferential defect (semi-elliptical surface-breaking surface defect) postulated to exist on both internal and external surfaces has been used. Limiting defect sizes have been calculated following the R6 procedure.
Four cases have been investigated. After presenting the investigation results, conclusions are drawn.
Investigation of In-Flow Fluidelastic Instability of Square Tube Arrays Subjected to Air Cross Flow
Authors: Nakamura Tomomichi , Hagiwara Shinichiro , Yamada Joji , Usuki Kenji 
Published: November 2015

In-flow instability of tube arrays is a recent major issue in heat exchanger design since the event at a nuclear power plant in California [1]. In our previous tests [2], the effect of the pitch-to-diameter ratio on fluidelastic instability in triangular arrays is reported. This is one of the present major issues in the nuclear industry. However, tube arrays in some heat exchangers are arranged as a square array configuration. Then, it is important to study the in-flow instability on the case of square arrays.
The in-flow fluidelastic instability of square arrays is investigated in this report. It was easy to observe the in-flow instability of triangular arrays, but not for square arrays. The pitch-to-diameter ratio, P/D, is changed from 1.2 to 1.5. In-flow fluidelastic instability was not observed in the in-flow direction. Contrarily, the transverse instability is observed in all cases including the case of a single flexible cylinder. The test results are finally reported including the comparison with the triangular arrays.
Comparison of Transition Temperature Shifts From Notch Impact and Fracture Toughness (Master Curve) Testing
Authors: Brumovsky Milan , Kytka Milos , Falcnik Michal 
Published: November 2015

Evaluation of integrity and lifetime of reactor pressure vessels is usually based on fracture mechanics approach using empirical correlation between transition temperatures from impact tests and static fracture toughness test results in the form of “design curve”. Moreover, material degradation during operation is also usually monitored by impact surveillance specimen testing under the assumption that shifts in temperature dependencies if impact toughness and static fracture toughness are the same.
To verify this assumption, study of the correlation between these two shifts has been performed on WWER steels — 15Kh2MFA (Cr-Mo-V) and 15Kh2NMFA (Ni-Cr-Mo-V) types. Several sources of results have been used : (a) reconstitution of tested remains of Charpy V-notch impact test specimens from irradiated programs was performed to obtain pre-cracked Charpy size specimens for three point bending type fracture toughness testing, (b) comparison of tests results from surveillance programs irradiated by similar fluences, (c) experimental irradiation programs with accelerated irradiation in research reactor.
Additionally, some results from the recent study of irradiation embrittlement of high nickel weld are included — its behavior shows to some extraordinary tendency.
Thanks to the use of reconstitution, both series of specimen were irradiated under the same conditions — temperature and neutron fluence and comparison is reliable. Results show that transition temperatures from fracture toughness testing are larger than those from Charpy impact tests. Similar results have been obtained also for other two groups of results.
Elasto-Plastic Properties in Dissimilar Metal Weld Junctions: Stress-Strain Curves Determination for Constitutive Materials
Authors: Bourgeois M. , Ancelet O. , Chapuliot S. 
Published: November 2015

Within the framework of European project MULTIMETAL (Structural performance of multi-metal component), several fracture tests on different types of multi-material specimens have been performed. Present fracture toughness standard methods, e.g. ASTM E 1820 are not directly intended for Dissimilar Metal Weld (DMW). Therefore further investigations are needed in order to define the best practice in fracture mechanical tests and their analysis for DMWs.
Specimens are taken from welded plates: a narrow gap Inconel DMW junction between ferritic and austenitic stainless steels, designed and delivered by AREVA France. The aim of this work is to provide guidelines for the determination of DMW fracture properties. For that purpose, fracture specimen needs to be modelled by FE. The first task, which is the purpose of that paper, is the determination of the mechanical properties in terms of stress-strain curve of all DMW constitutive materials: austenitic stainless steel, ferritic steel, heat affected zone of the ferritic steel zone and Nickel alloy zone properties.
Conventional techniques for tensile test are not able to provide the tensile curve of the different materials constituting a weld joint. Image correlation techniques are well suitable but imply too long and difficult work for the images analysis. Therefore CEA has developed an intermediate solution based on laser sensors which provides a complete profile of the specimen during the tensile test. Using Bridgman equations, the stress and strain can be deduced from the measurement of the shape of the specimen (reduction of section but not only…). This innovative device has been used with new developments using local Bridgman equations in the post-processing of measurements. This allows to access to the material behaviour of several materials with only one specimen.
Numerical interpretation using FE methods is presented and confirms the material behaviour determined from the experimental work using Bridgman equations assumptions.
Finally, this combined experimental and numerical work has provided material data relative to all constitutive materials of the DMW junction. A hardened area in stainless steel material due to the welding process has been pointed out, and the heat affected zones of the ferritic material have been characterized in terms of stress-strain curves. The next stage of the project is to carry out tests on fracture specimens and to model these multi-materials specimens by FE. The gradient of elasto-plastic properties is now available for this next step.
Overview of Recent NUGENIA Activities Particularly in Relation to Structural Integrity
Authors: Sharples John , Keim Elisabeth 
Published: November 2015

NUGENIA, an international non-profit association founded under Belgian legislation and launched in March 2012, is dedicated to nuclear research and development (R&D) with a focus on Generation II and III power plants. NUGENIA is the integrated framework between industry, research and safety organisations for safe, reliable and competitive nuclear power production, and is aimed at running an open innovation marketplace, to promote the emergence of joint research and to facilitate the implementation and dissemination of R&D results. The technical scope of NUGENIA consists of eight technical areas. One of these areas, Technical Area 4, is associated with the structural integrity assessment of systems, structures and components.
A brief overview of recent NUGENIA activities in general is provided in this paper and a specific focus is given on developments in relation to Technical Area 4.