bluuebunny/crossref_metadata_2025_split huggingface dataset:
A latent profile analysis of math anxiety and core beliefs toward mathematics among children
Authors: Orbach Lars , Fritz Annemarie 
Published: November 2021

AbstractRecent findings on the negative impacts of math anxiety (MA) have raised questions for educational and clinical research regarding effective intervention programs. One basic approach for developing intervention programs in the field of cognitive behavioral therapy is to gain an in‐depth understanding of the cognitive beliefs of children with a specific mental problem. By applying latent profile analysis (LPA), the present study aimed at identifying different patterns of MA and providing further insights into its cognitive phenomenology. For this purpose, trait‐MA, state‐MA, attitudes toward math, academic self‐concepts, fixed/growth mindsets, executive functions, and math performance of 475 fourth and fifth graders (48.2% girls) were assessed. LPA indicated seven distinct profiles characterized by different dimensions and patterns of state‐MA, trait‐MA, and core beliefs toward math. Furthermore, the profiles showed clearly different math performances. The weakest performances were found for a profile with highest state‐MA, high trait‐MA, and negative cognitive beliefs toward math and a profile with average state‐MA, high trait‐MA, and negative cognitive beliefs toward math, whereas the highest achieving profile had no state‐MA, high trait‐MA, and very positive cognitive beliefs toward math. The findings underline the complexity of MA and emphasize the necessity to develop interventions with careful consideration of the heterogeneous patterns.
The role of phase and orientation for ERP modulations of spectrum‐manipulated fearful and neutral faces
Authors: Bruchmann Maximilian , Schindler Sebastian , Dinyarian Mandana , Straube Thomas 
Published: November 2021

AbstractPrioritized processing of fearful compared to neutral faces has been proposed to result from evolutionary adaptation of the contrast sensitivity function (CSF) to the features of emotionally relevant faces and/or vice versa. However, it is unknown whether a stimulus merely has to feature the amplitude spectrum of a fearful face to be prioritized or whether the relevant spatial frequencies have to occur with specific phases and orientations. Prioritized processing is indexed by specific increases of Event‐Related Potentials (ERPs) of the EEG and occurs throughout different early processing stages, indexed by emotion‐related modulations of the P1, N170, and EPN. In this pre‐registered study, we manipulated phase and amplitude properties of the Fourier spectra of neutral and fearful faces to test the effect of phase coherence (PC, face vs. scramble) and orientation coherence (OC, original vs. rotational average) and their interactions with differential emotion processing. We found that differential emotion processing was not present at the level of P1 but strongly affected N170 and EPN. In both cases, intact phase coherence was required for enhanced processing of fearful faces. OC did not interact with emotion. While faces produced the typical N170 effect, we observed a reversed effect for scrambles. Additional exploratory independent component analysis (ICA) suggests that this reversal could signal a mismatch between an early "perceptual hypothesis" and feedback of configural information. In line with our expectations, fearful‐neutral differences for the N170 and EPN depend on configural information, i.e., recognizable faces.
Race and class patterns of income inequality during postrecession periods
Authors: DiPasquale Giacomo , Gomies Matthew , Rodriguez Javier M. 
Published: November 2021

AbstractRecent research on increasing income inequality focuses on recessions’ role on the income distribution and racial disparities in the United States.ObjectiveThis study expands this research by focusing on the evolution of racial income inequality during postrecession periods. We hypothesize that differential recovery trends by race and income rank during postrecession periods exacerbate between‐ and within‐race income inequality. Specifically, we examine postrecession trajectories of race‐specific weekly earnings for the bottom and top 10 percent in the U.S. weekly earnings distribution.MethodWe apply a break‐spline regression approach to quarterly weekly earnings data (2001–2018) collected from the Bureau of Labor Statistics and the Federal Reserve Bank of Saint Louis for the 2001 Recession, the Great Recession, and between‐recession periods.ResultsResults show an increase in income inequality between the bottom and top 10 percent in the weekly earnings distribution during recovery periods. For all races, the bottom 10 percent recovered from recessions slower and later than the top 10 percent. We also find that Asian Americans’ weekly earnings influence between‐ and within‐race income inequality during postrecession periods.ConclusionIncome inequality—overall and across races—is entrenched as racial/ethnic minorities and the poor are particularly vulnerable to recessions and are neither catching up nor recovering during upturns of the economy.
A Novel Variable Extensometer Method for Measuring Ductility Scaling Parameters From Single Specimens
Authors: Smith Adam J. , Maxwell Hannah L. , Mirmohammad Hadi , Kingstedt Owen T. , Berke Ryan B. 
Published: November 2021

Abstract
Macro-scale ductility is not an intrinsic material property but is dependent on the overall geometry of the specimen. To account for variety in specimen geometries, multiple ductility scaling laws have been developed, which scale ductility between different specimen sizes. Traditionally, these ductility laws rely on testing multiple different specimens of varying sizes to obtain material parameters, often done by varying gauge lengths. With the use of digital image correlation (DIC), this study presents a technique where multiple different gauge lengths are extracted from a single specimen to obtain ductility scaling parameters from a single experiment. This technique provides orders of magnitude more data from each specimen than previous techniques. This variable extensometer method is then validated by testing multiple different geometries, and select scaling laws are then compared.
An Assessment of Effects of Nanofluids on Heat Transfer Performance of Two-Phase Cooling Systems
Authors: Korobko Alexander V. , Fateh Sana 
Published: November 2021

Abstract
The recent increase in complexity of computations and the expansion of edge computing have led to the emergence of high power density data centers with an urgent demand for more advanced thermal management systems. Two-phase passive cooling systems such as thermosyphons and heat pipes have been widely used in industry to maintain the temperature of the servers below the threshold of failure and carry away a large quantity of heat from a small area. Such systems are economically viable and sustainable since they have no moving parts and consume lower power. However, an upgrade to these cooling systems is imminent due to the ever-increasing power densities of the data centers and more challenging thermal management issues faced by the industry. Nanofluids have emerged recently as a new class of cooling liquids claiming to enhance the heat transfer performance in single and two-phase cooling systems. As per several studies presented in this paper, the thermal performance of thermosyphons is shown to be enhanced by employing nanofluids. In this paper, a comprehensive review is presented on the effect of nanofluids in improving the Critical Heat Flux (CHF) and Heat Transfer Coefficient (HTC) in two-phase cooling systems. The boiling phenomenon and working principles of thermosyphons will be discussed to understand the underlying mechanisms affecting heat transfer in the evaporator region, where the heat is absorbed from the source. The impact of nanoparticle features, concentration, and deposition pattern on HTC enhancement will also be studied. Additionally, estimates of the heat dissipation improvement by using nanofluids along with the bottlenecks and challenges faced in applying such fluids practically are reviewed as well. In conclusion, recommendations are made for future research needed to overcome the risks and commercialize the nanofluids in two-phase cooling systems for providing significant improvement in heat transfer performance as compared to conventional working fluids.
Phase Change Material’s (PCMs) Effectiveness Index for Rapid Assessment in Thermal Management of Transient Pulse Electronics
Authors: Olivera Adrian , Rosales Jhonathan , Quintero Pedro O. 
Published: November 2021

Abstract
The use of nanocomposites phase change materials (PCMs) as transient passive thermal solution for high power electronics have been growing in the last few years. Typical application loads are in timescales of seconds, milliseconds, or nanoseconds; where the use of traditional cooling solutions, designed for steady state conduction/convection, are no longer effective. Common combinations for nanocomposites, with a PCM matrix and metal nanoparticle fillers, are Wax-Ag/Au or Sugars-Ag/Au. However, there is a lack of a performance parameter to guide the decision making during the co-design process. In this investigation we propose the formulation of an effectiveness parameter (index), in terms of response time and effective PCM volume selection, to assist the tradeoff analysis required for complex systems. The index is defined by the ratio of the PCM volume’s phase change time to the melting time. When heating a PCM, with a finite thickness, a melt front is formed as soon as the interface with the heat source begins melting while the heat source continues adding energy into the material. This melting front will achieve a constant velocity through the thickness owing to the high volumetric latent heat; therefore, the volume changes phase with an accompanying linear temperature increase. This non-isothermal phenomenon drives the definition of our proposed phase change energy term, or modified latent heat, for non-isothermal transient phase changing systems such as those encountered in pulsed power electronics. The calculated modified latent heat was validated, with a 1.68% difference, when compared to Field’s metal experimental data using a 12W heater and the Temperature-Energy diagram. Furthermore, a 0.39% difference was obtained between the calculated modified latent heat of organic PCM PT-58 and the experimental data with a 2W heater.
Operational Map and Thermal Performance of a Thermosyphon Cooling System for Compact Servers
Authors: Amalfi Raffaele L. , Hoang Cong H. , Enright Ryan , Cataldo Filippo , Marcinichen Jackson B. , Thome John R. 
Published: November 2021

Abstract
This paper advances the state-of-the-art in novel passive two-phase systems for more efficient cooling of datacenters and telecom central offices compared to the traditional air-based cooling solutions (e.g. aisle-based containment systems). The proposed passive two-phase technology uses numerous server-level thermosyphons to dissipate the heat generated by critical components, such as central processing units, accelerators, etc., with the flexibility of selecting the rack-level and room-level cooling elements depending on the deployment scenarios. The main goal of this paper is to experimentally investigate the thermal performance and maximum heat removal capability of a server-level thermosyphon for cooling compact servers. The experimental apparatus, built at Nokia Bell Labs, incorporates a single 7-cm high liquid-cooled thermosyphon that fits within a 2U server (smaller form factors can be achieved by a proper design that would further reduce the thermosyphon’s height). The heat source is represented by a pseudo-chip, composed of six parallel cartridge heaters installed in a copper block that incorporates local temperature measurements and is able of dissipating a total power of ≈ 500 W over a footprint area of 3.5 cm × 3.5 cm (corresponding heat flux of ≈ 41 W/cm2). Steady-state experiments were carried out at various heat loads up to 240 W (corresponding heat flux of ≈ 20 W/cm2), filling ratios and secondary side inlet conditions (coolant temperatures and mass flow rates), using R1234ze(E) and deionized water as the working fluids on the primary and secondary side, respectively. Test results demonstrate high heat transfer performance of the server-level thermosyphon over a wide range of conditions, and operating points are identified and classified into an operational map. Thermosyphon-based cooling systems across multiple length scales can significantly improve operation in terms of lowering energy consumption, allowing for higher hardware density, increased processing speed and reliability.
Thermal-Hydraulic Analytical Models of Split-Flow Microchannel Liquid-Cooled Cold Plates With Flow Impingement
Authors: Kisitu Deogratius , Ortega Alfonso 
Published: November 2021

Abstract
Impingement split flow liquid-cooled microchannel cold plates are one of several flow configurations used for single-phase liquid cooling. Split flow or top-in/side-exit (TISE) cold plates divide the flow into two branches thus resulting in halved or reduced flow rates and flow lengths, compared to traditional side-in /side-exit (SISE) or parallel flow cold plates. This has the effect of reducing the pressure drop because of the shorter flow length and lower flow rate and increasing the heat transfer coefficient due to thermally developing as opposed to fully developed flow. It is also claimed that the impinging flow increases the heat transfer coefficient on the base plate in the region of impingement. Because of the downward impinging and turning flow, there are no exact analytical models for this flow configuration. Computational and experimental studies have been performed, but there are no useful compact analytical models in the literature that can be used to predict the performance of these impingement cold plates. Results are presented for novel physics-based laminar flow models for a TISE microchannel cold plate based on an equivalent parallel channel flow approach. We show that the new models accurately predict the thermal-hydraulic performance over a wide range of parameters.
Effect of Mechanical Cycling at Elevated Temperatures on The Constitutive Properties and Microstructure of Lead Free Solder Alloys
Authors: Hoque Mohd Aminul , Haq Mohammad Ashraful , Suhling Jeffrey C. , Lall Pradeep 
Published: November 2021

Abstract
Solder joints in electronic packages often experience fatigue failures due to cyclic mechanical stresses and strains in fluctuating temperature environments. These stresses and strains are induced by mismatches in coefficients of thermal expansion, and lead to damage accumulation that contributes to crack initiation, crack propagation, and eventually to failure. In this study, we have tried to compare the effects of elevated mechanical cycling on SAC305 and SAC+Bi (SAC_Q). Initially, small uniaxial cylindrical samples of both alloys were prepared and reflowed in a reflow oven. These samples were then mechanically cycled for various durations at testing temperatures of 100 °C. The measured cyclic stress-strain curves were used to characterize the evolution of the hysteresis loop properties (peak stress, hysteresis loop area, and plastic strain range) with high temperature mechanical cycling. In addition, uniaxial tensile tests and creep tests were also conducted on specimens that had been previously mechanically cycled for various durations (e.g 0, 50, 100, 200, and 300 cycles) at an elevated temperature. This allowed us to study the evolution of the constitutive behavior of the solder alloys that occurred during the high temperature mechanical cycling due to the fatigue damage that builds up in the specimens. The reductions in the properties that occur during high temperature mechanical cycling were also correlated with the corresponding changes in the microstructure of the specimens. Rectangular cross-sectioned samples of the two lead free solder alloys were polished and selected regions indented to track the changes in the microstructure of a fixed region with mechanical cycling at T = 100 °C. Using the results of this study, we are working to develop better fatigue criteria for lead free solders which are subjected to variable temperature applications.
Design for Reliability of Automotive Chip Scale Packages by Calibrated Virtual Prototyping
Authors: Döring Ralf , Dudek R. , Rzepka S. , Scheiter L. , Noack E. , Seiler B. 
Published: November 2021

Abstract
The thermomechanical reliability of the package and interconnections of assembled flip chip ball grid arrays (FC-BGA) is investigated in comparison to a reference chip scale package (CSP). Comparison is made using finite element (FE-) simulation.
A combined measuring-simulation technique is applied to calibrate the finite element simulations on a reference object. Adjustment is made based on the in-plane deformation field evaluated by both simulation and optical measurement. For the latter an optical sensor for in-plane deformation and strain field analysis is used based on grey scale correlation method. A methodology is presented and to extrapolate the knowledge gained to alternative package types of different but similar design in order to evaluate their suitability for the desired application before the physical fabrication (virtual prototyping).
Determination of High and Low Temperature High Strain Rate Mechanical Properties for SAC-R After Exposure to Isothermal Aging of 50°C Up To 8 Months
Authors: Lall Pradeep , Saha Mrinmoy , Suhling Jeff , Blecker Ken 
Published: November 2021

Abstract
Electronic parts may be subjected to continuous activity at high temperatures as well as high strain-rate loads in the oil exploration industry, military, automotive, avionics, and space applications, and parts may be stored in non-climate-controlled enclosures prior to deployment. Material properties evolve at even moderate temperatures after a long period of storage, according to previous studies on undoped SAC alloys. To reduce the aging effects, a number of alloy formulations have been proposed. Data on the mechanical properties of lead-free solder alloys used for interconnection in electronic packaging at high strain rates and high storage temperatures is very important for design optimization of electronic package sustainability at extreme temperatures, since SAC soldiers have shown degradation of mechanical properties after prolonged exposure to storage temperature. The use of dopants in SAC solder has been proposed as a solution to minimize degradation. In this study, After keeping the samples in storage at 50°C for 1–8 months, a doped SAC solder called SAC-R (Ecolloy) was subjected to high strain rate testing. Uniaxial impact hammer tensile tests were conducted on samples with no aging and samples that had been aged for up to 8 months to assess the mechanical properties of SAC-R at high and low operating temperatures ranging from −65°C to 200°C and the Mechanical properties has been compared with an undoped solder SAC 105. The constants for the Anand Visco-Plasticity model were calculated using the material data for SAC-R. By comparing model predictions of the uniaxial tensile test with experimental results, the model’s ability to reflect material constitutive behavior has been quantified.
Performance Characteristics of Additively Printed Strain Gauges Under Different Conditions of Temperature and High Stress Loads
Authors: Lall Pradeep , Thomas Tony , Narangaparambil Jinesh 
Published: November 2021

Abstract
Applications of printed sensors have increased to industrial, consumer electronics, and medical fields with the advancements in the technology of printing and the adaptability of ink. These sensors are used to monitor a variety of measurements, including temperature, humidity, strain, and sweat, with different systems. This paper studies the performance characteristics of additively printed strain sensors using a nScrypt machine with a direct-write printing technique. The ink used in this study is silver ink which is thermally cured and also has a solderable property. The thermal curing temperature and trace width of the printed silver trace is optimized for better performance in the strain measurements, shear load to failure, and resistivity. Once the printing characteristics of the trace are defined, strain gauges are printed on printed wiring boards (PWB) and are tested at different loading and temperature environments. The sustainability and repeatability of the sensor measurements at high-stress conditions are studied using combined temperature and vibration loads of up to 50 degrees Celsius and 10g acceleration levels. The strain characteristics of the printed strain gauges are studied by comparing them to a commercial strain gauge at a similar position on the test substrate. The repeatability and variation of the strain profile are studied with different conditions of temperature and acceleration conditions at different time instants during vibration. The gauge factor of the printed strain gauge is quantified using a 3-point bending experiment with printed and commercial strain gauges at symmetrical locations of the substrate.
Cooling of High Powered GPUs Using Liquid Nitrogen Cold Plates Made With Additive Manufacturing
Authors: Nordlund Alec , McAfee Rachel , Ledsham Rebecca , Gess Joshua 
Published: November 2021

Abstract
Processor energy density is exceeding the capabilities of conventional air-cooling technology, but two-phase cooling has the potential to manage these resulting heat fluxes at reliable temperatures and higher electrical efficiency. When two-phase cooling is used in tandem with overclocking, data center footprints are reduced as individual chip processing power can be set at limits well beyond the manufacturer’s Thermal Design Power (TDP) or nominal operating condition. This study examines how Liquid Nitrogen (LN2) can be used with Additive Manufacturing (AM) and overclocking to increase the computational performance of a commercially available GPU. The power consumption and frequency relationship were established for both the cryogenically cooled solution and a comparative air-cooled solution. The cryogenic solution saw up to a 17.4% increase in compute efficiency and an 18.1% improvement in compute speed with comparable power efficiency at an equivalent performance level to the air-cooled solution. This study considers the computational performance and efficiency gains that can be acquired through cryogenic cooling on an individual graphics card, which can be replicated on a larger scale in data center applications.
On the last paper of Warren B. Hamilton
Authors: Hamilton* Lawrence C. 
Published: November 2021

ABSTRACT
When Warren Hamilton passed away in October 2018, he left behind the manuscript for a synthesis paper that was published in Earth-Science Reviews in 2019: “Toward a myth-free geodynamic history of Earth and its neighbors.” Integrating hundreds of detailed studies across four worlds and billions of years, the paper’s outlook is heterodox, presenting alternatives to conventional wisdom in every paragraph for almost 50 pages. During the last years of his life, Hamilton had worked steadily on this paper, which he viewed as the culmination of his long career. This chapter tells the story of how Hamilton wrote his last paper, summarizes a few of the many ideas it contains, and describes how, with help from his colleagues, the paper was posthumously completed and published.