bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Computational Study of the Thermodynamic Conditions Leading to Autoignition in Nanosecond Pulsed Discharges
Authors: Gururajan Vyaas , Scarcelli Riccardo , Karpatne Anand , Breden Douglas , Raja Laxminarayan , Biswas Sayan , Ekoto Isaac 
Published: December 2019

Abstract
Nanosecond pulsed discharges have attracted the attention of engine manufacturers due to the possibility of attaining distributed ignition sites that accelerate burn rates while resulting in very little electrode erosion. Multidimensional modeling tools currently capture the electrical structure of such discharges accurately, but resolving the chemical structure remains a challenging problem owing to the disparity of time-scales in streamer propagation (nanoseconds) and ignition phenomena (microseconds). The purpose of this study is to extend multidimensional results towards resolving the chemical structure in the wake of streamers (or the afterglow) by using a batch reactor model. This can afford the use of very detailed chemical kinetic information. The full non-equilibrium nature of the electrons is taken into account, along with fast gas heating, shock wave propagation, and thermal diffusion. The results shed light on ignition phenomena brought about by such discharges.
Numerical Investigation of a Central Fuel Property Hypothesis Under Boosted Spark-Ignition Conditions
Authors: Pal Pinaki , Kalvakala Krishna , Wu Yunchao , McNenly Matthew , Lapointe Simon , Whitesides Russell , Lu Tianfeng , Aggarwal Suresh K. , Som Sibendu 
Published: December 2019

Abstract
In the present work, a central fuel property hypothesis (CFPH), which states that fuel properties are sufficient to provide an indication of a fuel’s performance irrespective of its chemical composition, was numerically investigated. In particular, the objective of the study was to determine whether Research Octane Number (RON) and Motor Octane Number (MON), as fuel properties, are sufficient to describe a fuel’s knock-limited performance under boosted spark-ignition (SI) conditions within the framework of CFPH. To this end, four TPRF-bioblendstock surrogates having different compositions but matched RON (= 98) and MON (= 90), were first generated using a non-linear regression model based on artificial neural network (ANN). Three unconventional bioblendstocks were included in the analysis: Di-isobutylene (DIB), Isobutanol and Anisole. Skeletal reaction mechanisms were generated for the TPRF-DIB, TPRF-isobutanol and TPRF-anisole blends from a detailed kinetic mechanism. Thereafter, numerical simulations were performed for the fuel surrogates using the skeletal mechanisms and a virtual cooperative fuel research (CFR) engine model, under a representative boosted operating condition. In the computational fluid dynamics (CFD) model, the G-equation approach was employed to track the turbulent flame front and the well-stirred reactor model combined with multi-zone binning strategy was used to capture auto-ignition in the end-gas. In addition, laminar flame speed was tabulated for each blend as a function of pressure, temperature and equivalence ratio a priori, and the lookup tables were used to prescribe laminar flame speed as an input to the G-equation model. Parametric spark timing sweeps were performed for each fuel blend to determine the corresponding knock-limited spark advance (KLSA) and 50% burn point (CA50) at the respective KLSA timing. It was observed that despite same RON, MON and engine operating conditions, the TPRF-Anisole blend exhibited markedly different knock-limited performance from the other three blends. This deviation from the octane index (OI) expectation was shown to be caused by differences in laminar flame speed (LFS). However, it was found that relatively large fuel-specific differences in LFS (&gt; 20%) would have to be present to cause any appreciable deviation from the OI framework. Otherwise, RON and MON would still be robust enough to predict a fuel’s knock-limited performance.
Numerical Analysis of Pulse Laser Assisted Curing Region of Photocurable Resins
Authors: Nakamura Yuta , Fushinobu Kazuyoshi , Tamura Asato 
Published: December 2019

Abstract
AM (Additive manufacturing) technology has huge demand from industry for its high-speed fabricating, ability of fabricating complex shapes and low-cost fabrication which does not require expensive equipment such as molds. In particular, resolution of stereolithography technology is reaching to nanometer scale, and it is also expected to be utilized for nanodevice modeling.
One reason for stereolithography reaching to nanometer scale high resolution is due to the development of TPP (two-photon polymerization) technology.
As TPP requires advanced knowledge of optical, chemical and physical phenomena it is difficult to create a practical numerical method. On the other hand, there is a huge demand for prediction of curing range of resin from these parameters manufacturing of final products.
In this research, we discuss on numerical model which calculates curing region of photocurable resin by using short pulsed laser. The calculation will be conducted for line fabrication which will be more useful for practical use.
Prediction and Control Technique of the Paper Media Temperature After Fusing in Electrophotographic Process
Authors: Kawasaki Shunsuke , Kuramoto Shinichi , Fushinobu Kazuyoshi , Kato Koichi , Yamazaki Kimiharu , Hemmi Kaori 
Published: December 2019

Abstract
The production printer market is expected to increase due to the demand in high speed printing. In electrophotographic (EP) process, the printing speed is restricted by the toner cooling time. During continuous printing, if the printing speed is too high, following paper is printed before the toner on previous paper is solidified, which results in the adhesion of the toner on previous paper to the next paper. Therefore, it is important to reduce the toner cooling time to improve the printing speed. From the viewpoint of printing quality, although toner temperature is important in EP process, paper temperature is not. Therefore, to improve the printing speed without worsening printing quality, this report focuses on suppressing paper temperature rise after fusing, which means a method to predict paper temperature after fusing is required.
As one of effective approaches to predict paper temperature after fusing, numerical calculation based on physical model has been deployed. Constructing a physical model, however, has some problems such as complexity and uncertainty in particular parameter such as the thermal resistance. Printers have three dimensional and complex structure. The printing process itself is also a complex sequence to be appropriately modeled. It is also difficult to measure the thermal resistance and other properties due to the high speed motion of papers inside the machine. Therefore, as an alternative approach, machine learning can be used to correlate known inputs to the output temperature without relying on these uncertain parameters.
The objective of this research is to propose a new method for predicting and controlling the paper media temperature after fusing in electrophotographic process by machine learning.
Sensors are attached to the printer for the research. By using these sensors, temperature when printing is obtained. By using these data, machine learning is carried out to predict paper temperature after fusing.
This report constructs a new method to predict paper temperature after fusing. Our study demonstrates machine learning is an effective method for predicting and controlling the paper temperature after fusing.
Additive Manufactured, Low EMI, Non-Metallic Convective Heat Spreader Design and Optimization
Authors: Whitt Reece , Huitink David , Hudson Skyler , Nafis Bakhtiyar , Yuan Zhao , Narayanasamy Balaji , Deshpande Amol , Luo Fang , Imran Asif , Clarke Zion , Smith Sonya 
Published: December 2019

Abstract
With the increase of electronic device power density, thermal management and reliability are becoming increasingly important. First, increased density challenges the capability of conventional heat sinks to adequately dissipate heat. Secondly, higher frequency switching in wide bandgap power modules is introducing new issues in electromagnetic interference (EMI) in which metallic heat removal systems will couple and create damaging current ringing. Lastly, lightweight heat removal is required to meet the increasing needs of mobile power systems. In this effort we introduce an additive manufacturing pathway to produce custom-tailored heat removal systems using non-metallic materials, which take advantage of convective heat transfer to enable efficient thermal management. Herein, we leverage the precision of AM techniques in the development of 3D optimized flow channels for achieving enhanced effective convective heat transfer coefficients. The experimental performance of convective heat removal due to liquid impingement is compared with conventional heat sinks, with the requirement of simulating the heat transfer needed by a high voltage inverter. The implementation of non-metallic materials manufacturing is aimed to reduce EMI in a low weight and reduced cost package, making it useful for mobile power electronics.
Nanoindentation Testing of SAC305 Solder Joints Subjected to Thermal Cycling Loading
Authors: Fahim Abdullah , Hasan S. M. Kamrul , Suhling Jeffrey C. , Lall Pradeep 
Published: December 2019

Abstract
Solder joints in electronic packages are frequently exposed to thermal cycling environment. Such exposures can occur in real life application as well as in accelerated thermal cycling tests used for the fatigue behavior characterization. Because of temperature variations and CTE mismatches of the assembly materials, cyclic temperature leads to damage accumulation and material property evolution in the solder joints. This eventually results in crack initiation, and subsequent crack growth and failure.
In this study, the nanoindentation technique was used to understand the evolution of mechanical properties (modulus, hardness and creep behavior) of SAC305 BGA solder joints and Cu pad subjected to thermal cycling loading for various durations. In addition, microstructural changes in those joints that occur during thermal cycling were observed using both SEM and optical microscopy. BGA solder joint strip specimens were first prepared by cross sectioning BGA assemblies followed by surface polishing to facilitate SEM imaging and nanoindentation testing. The strip specimens were chosen to contain several single grain solder joints. This enabled large regions of solder material with equivalent mechanical behavior, which could then be indented several times after various durations of cycling.
After preparation, the solder joint strip samples were thermally cycled from T = −40 to 125 °C in an environmental chamber. At various points in the cycling (e.g. after 0, 50, 100, and 250 cycles), the package was taken out from the chamber, and nanoindentation was performed on each single grain joint and joint Cu pads to obtain the modulus, hardness, and creep behavior at 25 °C. This allowed the evolution of the mechanical properties with the duration of thermal cycling to be determined. Moreover, microstructural changes were also observed after various durations of cycling using optical microscopy. From the nanoindentation test results, it was found that the modulus and hardness of the SAC305 solder joints dropped significantly with thermal cycling. However, the Cu pad did not show any change in the mechanical behavior during cycling. Moreover, the nanoindentation creep test results showed significant increases in the creep deformation for solder joints whereas Cu pad did now show any significant changes in creep behavior when both of them were subjected to thermal cycling up to 250 cycles.
Application of Electronics Packaging Fundamentals to Photovoltaic Interconnects and Packaging
Authors: Spinella Laura , Bosco Nick 
Published: December 2019

Abstract
The energy capacity of photovoltaic (PV) installations worldwide has increased significantly in the last decade, increasing the demand for rigorous investigation of the physical phenomena causing degradation and failures in PV modules. As PV reliability science develops, established methods and approaches from longer-standing industries can inform and expedite PV reliability advances. This work demonstrates how thermomechanical solder bond fatigue models derived for electronics packaging applications can be applied to both standard and emerging PV interconnect designs. This expertise cannot be directly translated to PV however, as target PV module lifetimes are significantly longer than most electronics and the modules must withstand the natural climate wherever they are deployed. Verification of analytical reliability models is then an additional challenge, due to model size, test time, and climate variability. Furthermore, unconventional materials, such as low-temperature solders, are now being integrated into PV designs, for which appropriate material models must be selected and material parameters derived. In this paper, the current state of PV interconnect research is explored, with an emphasis on the experimental and simulation approaches and models being used for this work. Recent results for standard module architectures as well as emerging interconnect schemes are discussed.
Numerical Investigation on Electromigration Oriented Failure of Lead Free Solder Joints With Aging Effects
Authors: Ahmed Tusher , Motalab Mohammad , Suhling Jeffrey C. 
Published: December 2019

Abstract
Lead free solder materials have replaced lead based solder materials nowadays for increased environmental concern. Further miniaturization of electronic solder joints in packages has caused electromigration to dominate among all the reliability issues found in electronic packages. This current investigation deals with the review of mechanical property degradations of SAC305(Sn-96.5Ag-3.0Cu-0.5) solder materials due to thermal aging and their effects on electromigration oriented failure of small scale flip chip solder bumps. Thermal aging causes significant degradation of ultimate strength as well as elastic modulus of the SAC solder material. This degradation in stress-strain relationship plays an utterly important role in electromigration oriented mass diffusion and subsequent failure in the solder joints. This research highlights the linkage between thermal aging oriented strength degradation and its effect on electromigration oriented void propagation rate and time to failure. Structural-electric diffusion analyses with a finite element analysis software have been performed and results derived from different aging conditions (1 to 60 days of aging at 100 °C) at different electromigration temperatures have revealed that mass diffusion due to electromigration and associated stress migration actually reduces with the increment of aging time and thus increases time to failure in case of a flip chip solder joint. Simulation results have been found to be in good agreement with the experimental results available in literatures. These results can pave way to further detailed experimental investigation on effect of thermal aging on electromigration.
Effects of Shear Cycling on the Mechanical Properties of SAC and SAC+X Lead Free Solder Joints
Authors: Hoque Mohd Aminul , Chowdhury Md Mahmudur , Hamasha Sa’d , Suhling Jeffrey C. , Lall Pradeep 
Published: December 2019

Abstract
Solder joint reliability is a chief concern in electronic assemblies. Electronic packages consist of various materials, each having their own Coefficient of Thermal Expansion (CTE). When assembled packages experience high temperature gradients and thermal cycles, a mismatch in the CTE values brings about cyclic shear strains in the solder joints, which can ultimately lead to failure. Thus, it is important to understand the effects of shear cycling on the damage accumulated in solder joints.
Previous studies conducted on the effect of mechanical cycling on the material behavior of lead free solders have been performed on bulk samples subjected to tension and compression. Our goal in this study was to determine the evolution of the mechanical properties of doped lead free solder joints when subjected to mechanical shear cycling. Experiments conducted on actual solder joints would help us gain a better understanding on the real life effects of shear cycling. The test specimens consisted of a 3 × 3 array of nine solder joints of approximately 0.75 mm diameter. With the aid of specially designed test fixtures, the specimens were gripped and then subjected to mechanical cycling in the shear using an Instron Micromechanical tester. Testing was performed on both SAC305 and SACX (SAC+Bi) solder joints. The joints were cycled for certain durations, and a nanoindentation system was used to measure the evolution of the mechanical properties (elastic modulus, hardness, creep rate) as a function of the number of shear cycles.
Fatigue Delamination Crack Growth of Potting Compounds in PCB/Epoxy Interfaces Under Flexure Loading
Authors: Lall Pradeep , Dornala Kalyan , Suhling Jeff , Deep John , Lowe Ryan 
Published: December 2019

Abstract
Electronics components operating under extreme thermo-mechanical stresses are often protected with underfills and potting encapsulation to isolate the severe stresses. By encapsulating the entire PCB, the resin provides complete insulation for the unit thereby combining good electrical properties with excellent mechanical protection. In military and defense applications these components are often subjected to mechanical shock loads of 50,000g and are expected to perform with reliability. Due to the bulk of material surrounding the PCB, potting and encapsulation resins are commonly two-part systems which when mixed together form a solid, fully-cured material, with no by-products. The cured potting materials are prone to interfacial delamination under dynamic shock loading which in turn potentially cause failures in the package interconnects. The study of interfacial fracture resistance in PCB/epoxy potting systems under dynamic shock loading is important in mitigating the risk of system failure in mission critical applications. In this paper, three types of epoxy potting compounds were used as an encapsulation on PCB samples. The potting compounds were selected based on their ultimate elongation under quasi-static loading. Potting compound, A is a stiffer material with 5% of ultimate elongation before failure. Potting compound, B is a moderately stiff material with 12% ultimate elongation. Finally, potting compound C is a softer material with 90% ultimate elongation before failure. The fracture properties and interfacial crack delamination of the PCB/epoxy interface were determined using three-point bend loading with a pre-crack at the interface. The fatigue crack growth of the interfacial delamination was characterized for the three epoxy systems. A prediction of number of cycles to failure and the performance of different epoxy system resistance under cyclic bending loading was assessed.
Computational Analysis for Thermal Optimization of Server for Single Phase Immersion Cooling
Authors: Gandhi Dhruvkumar , Chowdhury Uschas , Chauhan Tushar , Bansode Pratik , Saini Satyam , Shah Jimil M. , Agonafer Dereje 
Published: December 2019

Abstract
Complete immersion of servers in synthetic dielectric fluids is rapidly becoming a popular technique to minimize the energy consumed by data centers for cooling purposes. In general, immersion cooling offers noteworthy advantages over conventional air-cooling methods as synthetic dielectric fluids have high heat dissipation capacities which are roughly about 1200 times greater than air. Other advantages of dielectric fluid immersion cooling include even thermal profile on chips, reduction in noise and addressing reliability and operational enhancements like whisker formation and electrochemical migration. Nevertheless, lack of data published and availability of long-term reliability data on immersion cooling is insufficient which makes most of data centers operators reluctant to implement this technique. The first part of this paper will compare thermal performance of single-phase oil immersion cooled HP ProLiant DL160 G6 server against air cooled server using computational fluid dynamics on 6SigmaET®. Focus of the study are major components of the server like Central Processing Unit (CPU), Dual in Line Memory Module (DIMM), Input/output Hub (IOH) chip and Input/output controller Hub (ICH). The second part of this paper focuses on thermal performance optimization of oil immersion cooled servers by varying inlet oil temperature, flow rate and using different fluid.
The Role of Interfacial Thermal Resistance in Li-Ion Battery Thermal Management
Authors: Yang Chuanbo , Cao Lei 
Published: December 2019

Abstract
Temperature critically affects the performance, life and safety of lithium-ion batteries. Therefore, it is essential to understand heat generation and dissipation within individual battery cells and battery packs to plan a proper thermal management strategy. One of the key challenges is that interfacial heat transfer of a battery unit is difficult to quantify. The steady-state absolute method and the transient laser-flash-diffusivity method were employed to measure heat conductivities of battery layer stacks and individual battery layer separately. Results show flash diffusivity method gives higher thermal conductivity at both cross-plane and in-plane directions. The difference is primarily caused by interfacial thermal resistance so that it can be estimated by steady-state and transient measurements.
To investigate the effects of interfacial thermal transport beyond individual cell level, a multiphysics battery model is used. The model is built upon a multi-scale multi-domain modeling framework for battery packs that accounts for the interplay across multiple physical phenomena. Benefits of a battery module using thermal management materials are quantified through numerical experiments. During a thermal runaway event, it is found interfacial thermal resistance can mitigate thermal runaway in a battery module by significantly reducing heat transfer between cells.
Impaired Insulin Profiles Following a Single Night of Sleep Restriction: The Impact of Acute Sprint Interval Exercise
Authors: Sweeney Emma L. , Peart Daniel J. , Kyza Irene , Harkes Thomas , Ellis Jason G. , Walshe Ian H. 
Published: December 2019

Experimental sleep restriction (SR) has demonstrated reduced insulin sensitivity in healthy individuals. Exercise is well-known to be beneficial for metabolic health. A single bout of exercise has the capacity to increase insulin sensitivity for up to 2 days. Therefore, the current study aimed to determine if sprint interval exercise could attenuate the impairment in insulin sensitivity after one night of SR in healthy males. Nineteen males were recruited for this randomized crossover study which consisted of four conditions—control, SR, control plus exercise, and sleep restriction plus exercise. Time in bed was 8 hr (2300–0700) in the control conditions and 4 hr (0300–0700) in the SR conditions. Conditions were separated by a 1-week entraining period. Participants slept at home, and compliance was assessed using wrist actigraphy. Following the night of experimental sleep, participants either conducted sprint interval exercise or rested for the equivalent duration. An oral glucose tolerance test was then conducted. Blood samples were obtained at regular intervals for measurement of glucose and insulin. Insulin concentrations were higher in SR than control (p = .022). Late-phase insulin area under the curve was significantly lower in sleep restriction plus exercise than SR (862 ± 589 and 1,267 ± 558; p = .004). Glucose area under the curve was not different between conditions (p = .207). These findings suggest that exercise improves the late postprandial response following a single night of SR.