bluuebunny/crossref_metadata_2025_split huggingface dataset:
Failure Mechanisms and Modeling in High Power Optical Device Packaging: Semiconductor Laser Diodes — A Case Study
Authors: Dhamdhere Ajit R. , Schmidt W. F. , Malshe Ajay P. , Brown W. D. , Yedave S. N. 
Published: November 2021

Abstract
High power semiconductor laser diodes are finding increasing applications in diverse areas such as the biomedical field, materials processing, cosmetics, etc. Dissimilar materials integration and thermal management are some of the primary challenges in the fabrication and packaging of reliable laser diode systems. For example, in a specific case, a high power diode must be mounted with its epitaxy-side down, so as to achieve efficient heat transfer. The device and package junction, particularly the die attach interface, is desired to be void-free (i.e., micro-defect free), stress-managed, and contamination-free for uniform optical delivery and reliable optical alignment. Soft solders used in optoelectronic applications are typically subjected to extreme service conditions that may exceed two-thirds of the melting point. As a result, it is expected that the solder microstructure will be metastable and subjected to nearly constant modification during processing and device operation. In this study, we investigated high power laser diode packages aged under various conditions. Die attach interface, device stress, and microscopic defect analyses were carried out using primarily metallography, scanning electron microscopy (SEM), scanning acoustic microscopy, and micro-Raman spectroscopy. It was observed that the intermetallic compounds and microscopic physical defects at the die attach interface are detrimental to transient heat transfer, and thus, overall package reliability. Further, accurate device modeling can be used to assist in the overall understanding of the effect of packaging-induced stress on the performance and reliability of semiconductor lasers. The purpose of this modeling work was to better understand the interplay between electrical, optical, mechanical, and thermal effects in the operation of laser diodes. Micro-Raman spectroscopy was employed to explore the degradation of high power lasers due to mechanical stresses that appear in an active region of the diode during its growth, packaging, and operation. Using micro-Raman spectroscopy, we found that, although stress increases with aging, the shape of the stress profile and the strength changes randomly from one active region of the diode to another.
Creep Behavior of PB-Free Solders
Authors: Hua F. , Garner C. M. , Song H. G. , Morris J. W. 
Published: November 2021

Abstract
This study reports results of shear creep behavior of four Pb-free solders, Sn-3Ag-0.5Cu, Sn-3.5Ag, Sn-0.7Cu and Sn-10In-3.1Ag at 95θC and 130θC. At the stress levels tested, all the four solders showed the stress components close or larger than 5, typical for matrix creep. The calculated activation energies for Sn-0.7Cu, Sn-3.5Ag and Sn-3Ag-0.5Cu are from 103kJ/mol to 117kJ/mol, which are very close to the pure Sn self-diffusion activation energy (107kJ/mol). It suggested that the creep process is controlled by Sn bulk self-diffusion rate. The creep activation energy for Sn-10In-3.1Ag is higher in the range of 173–193kJ/mol.
The Sn-0.7Cu, Sn-3Ag-0.5Cu and Sn-10In-3.1Ag solder joints were also prepared with two different cooling rates, 3.5θC/min. (furnace-cooling) and 2.7θC/S (air-cooling) and tested at 130θC. It was observed that faster cooled solder joints have faster creep strain rates than slower cooled solder joints at the stress levels tested for all three solders, due to the fine and even distribution of intermetallic particles.
Viscoelastic Effects in Helical Flows of Polymer Fluids
Authors: Jeong Jae-Hyeuk , Leonov Arkady I. 
Published: November 2021

Abstract
The paper shows that detailed viscoelastic properties of helical flow can be exactly determined from those known for simple shearing as soon as a constitutive equation is specified. This paper also demonstrates the calculated characteristics of helical flow compared with experimental data.
PIV Measurements of Recirculation Patterns in a Stirred Tank
Authors: Hammad Khaled J. , Papadopoulos George 
Published: November 2021

Abstract
Phase-resolved PIV measurements were performed to reveal the detailed flow features within a triple impeller stirredtank. Two tests were performed: low and high rotational speeds, 175 and 575 RPM, respectively. The tests used an optically transparent mixing vessel to measure the 2D flow field characteristics along a vertical plane passing through the tank center. The measurements disclosed interesting in-plane vortical behavior that when measured at two angular positions with respect to the blade passage further indicated the three-dimensional flow behavior. For the low RPM case, a laminar flow nature was apparent, whereby vortical toroidal structures spanned around the stirrer vertical axis. Six such structures were dominant. For the high RPM case and for θ = 0° six dominant vortical structures were apparent. Their r-z plane location and size were different from that for the low RPM case. With blade passage four of these vortical structures appeared to merge into two, suggesting that constant toroidal vortical structures spanning around the stirrer axis were absent from the high RPM case. A switch between six distinct and four distinct in-plane vortical structures as the blades pass through the measurement plane further suggested a transitional flow field at 575 RPM.
Parameter Estimation in a Hydrostatic System Using Extended Kalman Filter
Authors: Chinniah Yuvin A. , Burton Richard , Habibi Saeid 
Published: November 2021

Abstract
In this paper, the Extended Kalman Filter (EKF) estimation technique is applied to a novel hydrostatic actuation system referred to as the Electrohydraulic Actuator (EHA). A state space model of the EHA is developed and the effective bulk modulus is estimated in simulation. The EHA is a high performance actuation system capable of moving large loads with very high accuracy and precision. In a practical situation, this parameter is very difficult to measure directly as it depends on entrained air which cannot be known at a particular point of time. The bulk modulus is critical for system response and a low bulk modulus as a result of air in the system can seriously hinder the performance of EHA and cause safety problems.
Correlations of Fin-Tube Heat Exchanger Performance Data Using Genetic Algorithms, Simulated Annealing and Interval Methods
Authors: Pacheco-Vega Arturo , Sen Mihir , Yang K. T. , McClain Rodney L. 
Published: November 2021

Abstract
We consider the prediction of the performance of an air-water fin-tube compact heat exchanger using correlations of the power-law type. Measurements of the in-tube and over-tube mass flow rates, inlet temperatures and heat transfer rates, with water as the in-tube fluid and air as the over-tube fluid, are used to show that a regression analysis for the best-fit correlation of a prescribed form does not provide a unique answer in the heat rate predictions and that a global, rather than a local, search for the best correlation should be conducted. To this end, we propose the application of three different global optimization techniques to find the constants in a prescribed correlating function which can then be used to predict the performance of this heat exchanger under different operating conditions. Comparisons of the different results are then made to determine the relative advantages and disadvantages among the methods in terms of efficiency, accuracy and certainty of the results. Every method is found to have advantages over the others, and the results demonstrate that all three techniques are able to predict well the performance of this heat exchanger.
An Advanced Multiblock Solution Procedure and its Application to Silicon Tube Growth by EFG Technique
Authors: Sun D. , Zhang H. , Prasad V. , Mackintosh B. , Kalejs J. P. 
Published: November 2021

Abstract
The Edge-defined Film-fed Growth (EFG) is a widely used technique for the growth of polycrystalline silicon from its melt in the form of ribbon and hollow cylinders. The current octagonal tube growth technique has been modified successfully to produce 50 cm diameter circular tube for photovoltaic application by ASE Americas, Inc. A comprehensive growth model has been developed that accounts for conduction, convection and radiation heat transfer in the growth system, electromagnetic heating, and solidification. To improve the efficiency and accuracy of the model, two sets of grid system have been employed. A single structured grid system is used to calculate the magnetic potential field generated by radio-frequency induction heater, and a non-matching multi-block grid system to solve the temperature field with fine grids in the vicinity of the die-tip and silicon tube. Two sets of grid system overlap each other. A multi-block solution procedure has been developed satisfying the flux conservation at the block interfaces. The new solution procedure is used to simulate the existing octagonal silicon tube growth. The results obtained by different solvers, e.g., TDMA, CGSTAB, BiCGSTAB, SIP solver, are compared. It is evident that the CPU time is reduced dramatically if a fast solver, such as SIP or multigrid method, is used in the multi-block system.
Comparison of Sharp Interface Dendritic Growth Simulation With Microscopic Solvability Theory
Authors: Udaykumar H. S. , Mittal R. , Mao L. 
Published: November 2021

Abstract
We present and validate a numerical technique for computing dendritic growth of crystals from pure melts. The solidification process is computed in the diffusion-driven limit. The mixed Eulerian-Lagrangian framework treats the immersed phase boundary as a sharp solid-fluid interface and a conservative finite volume formulation allows boundary conditions at the moving surface to be exactly applied. The case of discontinuous material properties is also computed. The results from our calculations are compared with two-dimensional microscopic solvability theory. It is shown that the method predicts dendrite tip details in good agreement with solvability theory. The ability of the method to treat the front as a sharp entity and therefore to respect discontinuous material property variation at the solid-liquid interface is also shown to produce results in agreement with solvability and with other sharp interface simulations.
Thermally Optimum Natural Convection Cooled Longitudinal-Plate Heat Sinks With Horizontal Base Plates
Authors: Sikka K. K. , George C. 
Published: November 2021

Abstract
Longitudinal-plate fin heat sinks are optimized under natural convection conditions for the horizontal orientation of the heat sink base plate. The thermal performance of the heat sinks is numerically modeled. The fin height, thickness and spacing and heat sink width are systematically varied. The numerical results are validated by experimentation.
Results show that the thermal resistance of a heat sink minimizes for a certain number of fins on the base plate. The fin spacing-to-length ratio at which the minimum occurs is weakly dependent on the fin height and thickness and heat sink width. The flow fields reveal that the minimum occurs for the heat sink geometry in which the number of fins are maximized such that the flow velocity as the air exits the fins is fully developed. A correlation of the heat transfer with the heat sink geometrical parameters is also developed.
Non-Equilibrium Thermal Effects in Power Transistors
Authors: Raman Ashok , Walker D. G. , Fisher T. S. 
Published: November 2021

Abstract
The present work considers electro-thermal simulation of LDMOS devices and associated non-equilibrium effects. Simulations have been performed on three kinds of LDMOS i.e. bulk Si, partial SOI and full SOI. From the analysis, the extent of thermal non-equilibrium is determined from phonon temperature contours and electron energies in each case. The results indicate that, under similar operating conditions, non-equilibrium is more significant in the case of full SOI devices. Time development of acoustic phonon and lattice temperatures, obtained using two different heat source terms, was studied. This study provided insight into the difference between localized device heating in the electrically active region. The variation of optical and acoustic phonon temperatures with time is presented, and is used to identify time scales where thermal non-equilibrium would be significant.
Comparative Analysis of Implant Effectiveness in Maintaining the Stability of the Reverse Obliquity Hip Fracture
Authors: Kerr Kevin A. , Hashemi Javad , Post Jordan , Ngo Khai , Dabezies Eugene 
Published: November 2021

Abstract
The reverse obliquity hip fracture is an unstable intertrochanteric fracture. The existing treatments of the reverse obliquity hip fracture have a high failure rate leading to re-operation. The objective of this study was to design an experimental setup to systematically evaluate and quantitatively document the effectiveness of various fixation devices used to treat the reverse obliquity hip fracture.
The fixation devices tested and analyzed were 1) the 135 Degree Dynamic Hip Screw with a Trochanteric Stabilizing Plate (DHS/TSP)®, 2) the 95 Degree Condylar Hip Screw (CHS)®, and 3) the Recon Nail®. These devices were implanted in composite sawbone specimens with material properties close to that of human bone. All devices were tested under identical cyclic loading conditions. Based on a quantitative stability analysis, the 95 Degree CHS® showed the most promise for treatment of non-comminuted reverse obliquity hip fractures. The Recon nail® caused the bone to fracture at areas of high stress concentration and the 135 Degree DHS/TSP® was associated with high values of stress shielding. In this paper, the experimental set-up will be presented, the generated data will be discussed, and the performance of each fixation device will be analyzed.
Valued Insight or Act of Insubordination? How Context Shapes Coaches’ Perceptions of Challenge-Oriented Followership
Authors: Gottlieb Marcus , Eys Mark , Hardy James , Benson Alex J. 
Published: November 2021

Effective leadership is a collaborative effort, requiring a degree of complementarity in how people enact roles of leadership and followership. Using a novel online vignette methodology, we experimentally tested how three contextual factors influenced coaches’ responses to challenge-oriented acts of followership, as well as investigated two potential mechanisms. Coaches (N = 232) watched videos of an athlete provided unsolicited challenge-oriented feedback to a coach. Videos varied by the (a) athlete’s status, (b) presence of third-party observers, and (c) stage of the decision-making process. Following the video, we assessed coaches’ evaluations of the athlete. Challenge-oriented followership was perceived more favorably when enacted by an athlete in one-on-one (vs. in a group) and before a decision has been reached (vs. after a decision is reached). Coaches may appreciate proactivity from athletes in positions of followership, but challenge-oriented followership behaviors enacted at the wrong time and place can elicit negative reactions.
Effective actions for loop quantum cosmology in fourth-order gravity
Authors: Miranda Marcello , Vernieri Daniele , Capozziello Salvatore , Lobo Francisco S. N. 
Published: November 2021

AbstractLoop quantum cosmology (LQC) is a theory which renders the Big Bang initial singularity into a quantum bounce, by means of short-range repulsive quantum effects at the Planck scale. In this work, we are interested in reproducing the effective Friedmann equation of LQC, by considering a generic f(R, P, Q) theory of gravity, where $$R=g^{\mu \nu }R_{\mu \nu }$$

R
=

g

μ
ν

R

μ
ν

is the Ricci scalar, $$P=R_{\mu \nu }R^{\mu \nu }$$

P
=

R

μ
ν

R

μ
ν

, and $$Q=R_{\alpha \beta \mu \nu }R^{\alpha \beta \mu \nu }$$

Q
=

R

α
β
μ
ν

R

α
β
μ
ν

is the Kretschmann scalar. An order reduction technique allows us to work in f(R, P, Q) theories which are perturbatively close to General Relativity, and to deduce a modified Friedmann equation in the reduced theory. Requiring that the modified Friedmann equation mimics the effective Friedmann equation of LQC, we are able to derive several functional forms of f(R, P, Q). We discuss the necessary conditions to obtain viable bouncing cosmologies for the proposed effective actions of f(R, P, Q) theory of gravity.
Treatment-free Survival after Immune Checkpoint Inhibitor Therapy versus Targeted Therapy for Advanced Renal Cell Carcinoma: 42-Month Results of the CheckMate 214 Trial
Authors: Regan Meredith M. , Jegede Opeyemi A. , Mantia Charlene M. , Powles Thomas , Werner Lillian , Motzer Robert J. , Tannir Nizar M. , Lee Chung-Han , Tomita Yoshihiko , Voss Martin H. , Plimack Elizabeth R. , Choueiri Toni K. , Rini Brian I. , Hammers Hans J. , Escudier Bernard , Albiges Laurence , Huo Stephen , Del Tejo Viviana , Stwalley Brian , Atkins Michael B. , McDermott David F. 
Published: November 2021

Abstract

Purpose:
Patients discontinuing immuno-oncology regimens may experience periods of disease control without need for ongoing anticancer therapy, but toxicity may persist. We describe treatment-free survival (TFS), with and without toxicity.

Patients and Methods:
Data were analyzed from the randomized phase III CheckMate 214 trial of nivolumab plus ipilimumab (n = 550) versus sunitinib (n = 546) for treatment-naïve, advanced renal cell carcinoma (aRCC). TFS was estimated by the 42-month restricted mean times defined by the area between Kaplan–Meier curves for two time-to-event endpoints defined from randomization: time to protocol therapy cessation and time to subsequent systemic therapy initiation or death. TFS was subdivided as TFS with and without toxicity by counting days with ≥1 grade ≥3 treatment-related adverse event (TRAE).

Results:
At 42 months since randomization, 52% of nivolumab plus ipilimumab and 39% of sunitinib intermediate/poor-risk patients were alive; 18% and 5% surviving treatment-free, respectively. Among favorable-risk patients, 70% and 73% of nivolumab plus ipilimumab and sunitinib patients were alive; 20% and 9% treatment-free. Over the 42-month period, mean TFS was over twice as long after nivolumab plus ipilimumab than sunitinib for intermediate/poor-risk (6.9 vs. 3.1 months) and three times as long for favorable-risk patients (11.0 vs. 3.7 months). Mean TFS with grade ≥3 TRAEs was a small proportion of time for both treatments (0.6 vs. 0.3 months after nivolumab plus ipilimumab vs. sunitinib for intermediate/poor-risk, and 0.9 vs. 0.3 months for favorable-risk patients).

Conclusions:
Patients initiating first-line nivolumab plus ipilimumab for aRCC spent more survival time treatment-free without toxicity versus those on sunitinib, regardless of risk group.
Lower Cardiorespiratory Fitness Is Associated With Right Ventricular Geometry and Function – The Sedentary’s Heart: SHIP
Authors: Drzyzga Christine J. , Bahls Martin , Ittermann Till , Völzke Henry , Bülow Robin , Hammer Fabian , Ewert Ralf , Gläser Sven , Felix Stephan B. , Dörr Marcus , Markus Marcello R. P. 
Published: November 2021

Background
Lower cardiorespiratory fitness (CRF) is associated with an increased risk for cardiovascular disease. However, very little information is available about the association between lower CRF and right ventricular (RV) remodeling. We investigated the relationship between CRF and RV structure and function in a large, aging, and largely sedentary adult population–based cohort.

Methods and Results

We used cross‐sectional data of 2844 subjects (1486 women; median age, 51 years; interquartile range, 40–62 years) from the population‐based cohort SHIP (Study of Health in Pomerania) with echocardiography, of which 941 also had cardiac magnetic resonance imaging. We analyzed the associations of peak oxygen uptake with RV parameters determined by both imaging techniques using multivariable‐adjusted linear regression models. In echocardiography, a 1 L/min lower peak oxygen uptake was associated with a 1.18 mm (95% CI, 0.66–1.71;
P
<0.001) smaller RV end‐diastolic diameter and a 1.41 mm (95% CI, 0.90–1.92;
P
<0.001) narrower RV end‐diastolic outflow tract diameter. Similarly, using cardiac magnetic resonance imaging measurements, a 1 L/min lower peak oxygen uptake was associated with a 23.5 mL (95% CI, 18.7–28.4;
P
<0.001) smaller RV end‐diastolic volume, a 13.0 mL (95% CI, 9.81–16.2;
P
<0.001) lower RV end‐systolic volume, and a 10.7 mL/beat (95% CI, 8.10–13.3;
P
<0.001) lower RV stroke volume.

Conclusions
Our results indicate a significant association between CRF and RV remodeling. Lower CRF was associated with smaller RV chamber and lower RV systolic function, stroke volume, and cardiac output.
Predictors of Coronary Artery Calcium and Long‐Term Risks of Death, Myocardial Infarction, and Stroke in Young Adults
Authors: Javaid Aamir , Mitchell Joshua D. , Villines Todd C. 
Published: November 2021

Background
Coronary artery calcium (CAC) is well‐validated for cardiovascular disease risk stratification in middle to older–aged adults; however, the 2019 American College of Cardiology/American Heart Association guidelines state that more data are needed regarding the performance of CAC in low‐risk younger adults.

Methods and Results

We measured CAC in 13 397 patients aged 30 to 49 years without known cardiovascular disease or malignancy between 1997 and 2009. Outcomes of myocardial infarction (MI), stroke, major adverse cardiovascular events (MACE; MI, stroke, or cardiovascular death), and all‐cause mortality were assessed using Cox proportional hazard models, controlling for baseline risk factors (including atrial fibrillation for stroke and MACE) and the competing risk of death or noncardiac death as appropriate. The cohort (74% men, mean age 44 years, and 76% with ≤1 cardiovascular disease risk factor) had a 20.6% prevalence of any CAC. CAC was independently predicted by age, male sex, White race, and cardiovascular disease risk factors. Over a mean of 11 years of follow‐up, the relative adjusted subhazard ratio of CAC >0 was 2.9 for MI and 1.6 for MACE. CAC >100 was associated with significantly increased hazards of MI (adjusted subhazard ratio, 5.2), MACE (adjusted subhazard ratio, 3.1), stroke (adjusted subhazard ratio, 1.7), and all‐cause mortality (hazard ratio, 2.1). CAC significantly improved the prognostic accuracy of risk factors for MACE, MI, and all‐cause mortality by the likelihood ratio test (
P
<0.05).

Conclusions
CAC was prevalent in a large sample of low‐risk young adults. Those with any CAC had significantly higher long‐term hazards of MACE and MI, while severe CAC increased hazards for all outcomes including death. CAC may have utility for clinical decision‐making among select young adults.
Ubi suadebit placidos nox umida somnos (Ov. Fast. 2.635)
Authors: Coughlan Taylor S. 
Published: November 2021

Abstract
A study of a previously uncommented upon window reference of Vergil, Eclogues 1.55 through Aeneid 2.8-9 in Ovid, Fasti 2.635. The paper argues that the allusion to Ecl. 1.55 enriches our understanding of these lines on several levels. First, Ovid demonstrates his own appreciation of Vergilian intratextuality. Second, the allusion suggests a continuity between Tityrus’ pastoral locus amoenus, which Octavian was purported to have renewed, and the family cena that closes with a toast to Augustus as the pater of the Roman state. Lastly, the double reference to A. 2 and Ecl. 1 intertextually reinforces the calendrical turning away from the past and its dead to the living present initiated by the Caristia.