bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advancing in Data Centers Thermal Management: Experimental Assessment of Two-Phase Liquid Cooling Technology
Authors: Heydari Ali , Al-Zu'bi Omar , Manaserh Yaman , Gharaibeh Ahmad R. , Tipton Russ , Mehrabikermani Mehdi , Rodriguez Jeremy , Sammakia Bahgat 
Published: November 2024

Abstract
In response to the exponential growth of online platforms and the rise of web-based Artificial Intelligence (AI), the demand for computational power and the expansion of data centers have surged significantly. This trend necessitates advanced cooling strategies and heightened energy efficiency to address the increasing power densities of Information Technology (IT) equipment and the consequent rise in energy consumption. Consequently, there is a significant pivot towards efficient cooling mechanisms that emphasize thermal management and energy efficiency. Against this backdrop, our study thoroughly evaluates a two-phase direct-to-chip liquid cooling system’s ability to effectively manage and dissipate heat in high-density rack environments. Central to our research is the deployment of a highly efficient Refrigerant-to-Liquid (R2L) Coolant Distribution Unit (CDU) across multi-racks, which face high thermal demands. This innovative system, featuring an in-row pumped two-phase CDU with a cooling capacity of 160 kW, is intricately integrated with row and rack manifolds and server cooling loops to ensure optimal cooling performance. To accurately simulate the thermal loads encountered in real-world data center operations, the study employs Thermal Testing Vehicles (TTVs). These 3U TTVs are equipped with 2.5 kW heaters, covering an extensive area of 2500 mm2, thereby effectively replicating server thermal loads up to 10 kW. The investigation starts with a detailed description of the system’s design and continues with the commissioning process. This process includes extensive hydraulic and thermal testing, along with a comprehensive assessment of the impact of pressure drops across the system, focusing on supply manifolds, cooling loops, dry breaks, and return manifolds, utilizing Cooling Loops (CLs) each containing four Cold Plates (CPs). The study culminates in the analysis of experimental data from heating the TTVs, focusing on the efficiency of two-phase cooling in transferring heat from the TTVs to chilled water using R134a refrigerant as the performance benchmark. Future directions include exploring eco-friendly cooling practices by investigating alternative green refrigerants with low Global Warming Potential (GWP) to replace R134a, aligning with global sustainability goals and the imperative to reduce greenhouse gas emissions. The observed maximum values were calculated at a specific volumetric flow rate of 0.48 LPM/kW and a Tcase as low as 56.4 °C was achieved. These results demonstrate the system’s capability to significantly enhance thermal management in data centers, tackle the challenges presented by high-power density chips, and encourage broader adoption of two-phase cooling technologies as a sustainable strategy for thermal regulation in the face of increasing computational demands.
Enhanced Pool Boiling Heat Transfer Using Re-Entrant Surfaces
Authors: Zhou Yimin , Adera Solomon 
Published: November 2024

Abstract
Boiling is an essential heat and mass transfer process that is employed in numerous applications ranging from power generation and seawater desalination to thermal management of electronic components. Nucleate boiling, where vapor bubbles nucleate, grow, and depart from active nucleation sites, provides high heat transfer coefficient due to the large latent heat of phase change and the enhanced mixing of liquid near the heated surface caused by continuous bubble departure. Strategies for enhancing the nucleate boiling heat transfer include increasing active nucleation site density with micro/nano-sized roughness, improving vapor/gas entrainment in cavities, and increasing the apparent contact angle of the working fluid. Millimeter- or submillimeter-scale re-entrant grooves fabricated on metallic surfaces have been shown to enhance the heat transfer coefficient during nucleate boiling. Here, we experimentally measure the heat transfer coefficient of surfaces with microscale re-entrant cavities during pool boiling of de-ionized water. Boiling experiments were conducted on silicon surfaces with different surface structures, including vertical/cylindrical and re-entrant microcavities. The results reveal that, compared to the vertical microcavity surfaces, the reentrant microcavity surface reaches a maximum of 50% higher heat transfer coefficient under the same heat flux. Importantly, we observed a sudden temperature drop and heat flux rise at the onset of nucleate boiling for re-entrant microcavity surfaces. The heat transfer enhancement is attributed to the stronger vapor entrapment ability (that is, resistance to wetting by the working fluid) of the re-entrant microcavities. The results of this study provide design guidelines for re-entrant cavities for enhancing boiling heat transfer rate.
Thermal Management System of an Outer-Rotor-Motor-Based Traction Drive With Integrated Power Electronics in its Central Cavity
Authors: Kekelia Bidzina , Cousineau J. Emily , Chaudhary Rajneesh , Tomerlin Jeff , Narumanchi Sreekant , Rallabandi Vandana , Wilkins Jon , Chowdhury Shajjad , Barua Himel , Mohammad Mostak , Ozpineci Burak 
Published: November 2024

Abstract
Increasing power densities of electric vehicle traction drive systems necessitates combining the electric motor and the power electronics into one unit. A compact, integrated traction drive unit with fewer components also drives production costs down, enabling wider adoption of electric vehicles. However, the integration of power electronics in the electric machine is associated with challenges of designing an effective thermal management solution for the combined traction drive system. This paper focuses on the thermal management approach selected for Oak Ridge National Laboratory’s outer-rotor-motor-based integrated traction drive and evaluates its potential performance. The outer-rotor-motor configuration provided an opportunity for integration of the six-phase inverter in the available space in the central cavity of the internal stator. A cylindrical inverter enclosure with integrated coolant (water-ethylene glycol) channels in its walls was designed to enable heat removal from the power electronics. Numerical thermal-fluid modeling and initial channel/fin optimization results for the cylindrical heat sink are presented here. As permanent magnets are integrated in a high-speed (20 000 RPM) outer rotor, forced air convection provides cooling for the magnets. The magnets were segmented axially to mitigate the eddy current losses. Heat generated in the stator windings and laminations is removed by water-ethylene glycol coolant circulating in interpolar T-shape ceramic heat exchangers inserted between windings. General design concepts and numerical thermal-fluid simulations illustrating the electric motor thermal management solution are also presented.
Numerical Study of Two-Phase Immersion Cooling Limits for Bare Die Packages With Novec 649
Authors: Liu Tanya , Khalili Sadegh , Padilla Jorge , Iyengar Madhusudan 
Published: November 2024

Abstract
As chip power densities continue to increase, there is renewed interest in using two-phase immersion cooling (2PIC) as a passive thermal management mechanism to improve data center power density and operating efficiency. Traditional air cooling approaches are challenging to scale for high power chips due to costly requirements on cooling footprint, fan power, and increasingly untenable levels of acoustic noise. Single-phase liquid cooling can address some of these challenges but requires the introduction of complex fluid delivery manifolds, cold-plate loops and active pumps.
In this study, we use a semi-empirical, numerical approach to investigate two-phase immersion cooling limits for bare die packages with Novec 649, a low global warming potential (GWP) coolant. This simplified modeling method enables rapid parametric studies to extract relevant 2PIC thermal system design information without requiring experimental tanks or computationally expensive two-phase simulations.
From the results, we identify 2PIC thermal design power limits for bare die packages of various sizes with different distributions of heat sources and different boiler plate designs. We also identify key contributors to the 2PIC thermal resistance stack up and provide recommendations on potential improvements to overall junction to fluid resistance. Finally, we compare the 2PIC results against a single-phase, water-cooled coldplate case study and discuss pros and cons of both.
Numerical Study of Single-Phase Immersion Cooling Limits for Bare Die Packages
Authors: Khalili Sadegh , Liu Tanya , Padilla Jorge , Iyengar Madhusudan 
Published: November 2024

Abstract
Advances in packaging and semiconductor manufacturing have driven relentless increases in chip performance and power. As a result, air cooling powerful processors is becoming less effective and expensive. Single-phase immersion cooling has emerged as one of prominent technologies to enhance both cooling performance and efficiency. This paper aims to explore the boundaries of cooling performance of single-phase immersion cooling with a focus on the impacts of chip heat density and system-level constraints. Computational fluid dynamics (CFD) simulations were employed to conduct a parametric study on the influence of chip heat density and heat concentration on the cooling capabilities of immersion cooling. To push limitations of immersion cooling, forced convection immersion cooling is investigated. Furthermore, cooling capability limitations of immersion cooling are analyzed using a pseudo-ideal heatsink. Finally, results of single-phase immersion cooling are compared with direct liquid cooling (DLC) with cold plates.
Process-Performance Interactions Under Exposure to Sustained High Temperature for Additively Manufactured Electronics and SMT Assembly With Low-Temperature Curable Adhesives
Authors: Lall Pradeep , Bimali Sabina , Miller Scott 
Published: November 2024

Abstract
Rapid progress in technology necessitates an in-depth understanding of the enduring reliability of flexible printed circuitry constructed using different connecting materials. The adaptability of flexible printed circuits and their potential applications in a wide range of electronic devices, from automotive systems to wearable electronics, has garnered substantial interest in recent years. Thermal aging is an important factor that might potentially compromise the structural integrity and performance of electronic assemblies used in real-world applications. The reliability of flexible printed circuit assembly, particularly the bonding materials employed, is critical to the effective integration of flexible printed circuits into various applications. To gain a better understanding of the adhesive’s reliability under thermal aging, this study intends to carefully examine the effects of thermal aging on flexible printed circuitry. The objective of this study is to fill a gap in the literature by thoroughly investigating how thermal aging affects flexible printed circuit assemblies that are fabricated with room-temperature curable adhesives and high-temperature curable adhesives. This paper investigates processes aimed at achieving interconnects suitable for room-temperature processes, along with the use of water-based inks in printed electronics. The research delves into the examination of electrical performance and reliability tests within functional electronic circuitry. A comparison is made between the performance of low-temperature processable interconnects, coupled with water-based inks, and high-temperature processable interconnects for both test designs: individual components test and functional circuit test. The study includes the realization of a differentiator circuit through aerosol jet printing, employing low-temperature interconnects for component attachment. The circuit’s response is then compared with the simulated output. Finally, both the fabricated circuits are subjected to a thermal aging test for 1000 hours at a temperature of +85°C.
Performance and Reliability of In-Mold Direct-Write Signal Processing Circuits in Sustained High-Temperature Operation
Authors: Lall Pradeep , Sarwar Md Golam , Miller Scott 
Published: November 2024

Abstract
As additive in-mold technologies gain traction in the automotive sector, there is a growing need for long-term reliability data under harsh conditions and acceleration factors to predict the technology’s lifespan. This paper aims to investigate how the performance and reliability of a system or device evolve over time under continuous, elevated temperature conditions. The research methodology involves thorough investigations into materials, manufacturing processes, and testing procedures to assess the reliability of in-mold flexible electronics. To simulate the harsh conditions typically encountered by automotive components, printed thermoformed samples are subjected to prolonged exposure to high temperatures in this study. The nScrypt direct write platform is utilized for printing connection materials and conductive traces. Stretchable electrically conductive adhesive (ECA) is the connecting medium, while in-mold capable silver ink is utilized for the conductive traces. Thermoformable polycarbonate sheets are employed as substrate materials, with Formech-508FS utilized for thermoforming purposes. To evaluate the performance of the additively printed thermoformed circuit, an impedance analyzer is employed. A functional circuit schematic is constructed and tested using OrCAD PSpice to simulate the application. The actual output of the printed thermoformed circuit before exposure to high thermal conditions and during High-Temperature Operating Life (HTOL) testing is compared with the simulated performance of the circuit.
Oscillator Performance on Thermoformed Additive In-Mold Electronics for Automotive Applications
Authors: Lall Pradeep , Harsha Aditya , Kulkarni Shriram , Miller Scott 
Published: November 2024

Abstract
The concept of In-Mold Electronics (IME) has emerged as a highly transformative technology. IME offers huge potential for innovation by enabling automobile manufacturers to smoothly integrate electronic circuits with varied structures and surfaces across different products. Nevertheless, there is a lack of comprehensive study of the electrical attributes related to the IME circuits, specifically the screen-printed circuits on polycarbonate substrate followed by the thermoforming process to use in automobile applications. This study aims to investigate the influence of manufacturing parameters related to screen-printing and thermoforming on IME circuit performance, which is dedicated to its application in the automobile industry.
Additively Printed Circuits Using Biodegradable Substrates on Aerosol-Jet With Aqueous-Based Silver Conductive Paste Using ECA and Low-Temperature Interconnects
Authors: Lall Pradeep , Karakitie Daniel , Miller Scott 
Published: November 2024

Abstract
Traditionally, the manufacture of printed circuits relied on volatile organic solvent-based inks, a practice now scrutinized due to growing environmental concerns. There’s a notable shift towards water-based inks, offering a reduced environmental footprint by replacing volatile solvents with water as the carrier medium. However, despite their promising attributes, the functionalities and performances of circuits created with these sustainable inks remain relatively unexplored compared to their non-sustainable counterparts. This study addresses this knowledge gap, focusing on the innovative use of biodegradable PET substrates in the aerosol jet printing process. The research includes a comprehensive analysis of circuits created with sustainable water-based inks, with a specific focus on their application on biodegradable PET substrates. Key components were attached to these circuits using electrically conductive adhesives and low-temperature adhesives to compare the various effects of interconnects on the component attachment and the performance of the circuit using these interconnect adhesive materials. The evaluation involved a detailed analysis of component performance, particularly RLC components, in relation to operating frequency, and electron dispersive x-ray spectroscopy analysis. Extensive testing was performed to delineate the electrical and mechanical properties of the resulting circuits, with a specific focus on resistance values across varying sintering temperatures and durations. Preliminary findings indicate that modifying these parameters can enhance electrical properties, and optical methods were employed to characterize the printed trace outcomes.
Sequential High-Temperature Aging and High Humidity Exposure of Chip/Underfill Interfaces to Investigate the Evolution of Interfacial Stress Intensity Factor in FCBGA Stress Intensity
Authors: Lall Pradeep , Pandurangan Aathi , Choudhury Padmanava 
Published: November 2024

Abstract
In the realm of automotive applications, the reliability of Flip-Chip Ball Grid Array (FCBGA) packages is critical, and this study delves into the sequential effects of high-temperature aging and high humidity exposure on chip/underfill interfaces within FCBGA packages. The primary objective is to comprehensively investigate the evolution of interfacial stress intensity factors, crucial for predicting and mitigating potential failures in FCBGA packages used in automotive applications. Through systematic experimentation, the chip/underfill specimens undergo rigorous aging processes at elevated temperatures and subsequent exposure to high humidity conditions. High temperature and moisture-induced failures are some of the major contributing factors to failure in underhood automotive electronics. Exposure to high temperature and moisture weakens the critical interfaces in the FCBGA packages. Conventional studies on package-level interfaces often concentrate on the effects of individual environmental factors. Yet, real-world automotive electronics encounter a multitude of harsh conditions. The critical need to assess the impact of mechanical loads creates a substantial knowledge gap in our comprehension of these interfacial behaviors. Delamination at the chip/underfill (UF) interfaces is a common failure mode, evaluating interfacial fracture toughness crucial for assessing reliability. Any crack in this interface could propagate to the solder joints, leading to system failure. This study aims to investigate the failure modes of chip/UF Interfaces. Calculate the fracture toughness parameter and strain energy release rate for the interface fracture. Understand the effect of high-temperature aging at the chip/underfill and EMC/substrate Interface.
Investigation of Interfacial Reliability and Comparison Non-PFAS Underfills in FCBGAs Under Humidity and High-Temperature Exposure
Authors: Lall Pradeep , Pandurangan Aathi , Choudhury Padmanava 
Published: November 2024

Abstract
Poly-fluoroalkyl substances (PFAS) are fundamental to the intricate world of semiconductors, the engines powering our modern lives. Electronics on the automotive platform play a vital role in ensuring the safe and efficient operation of automobiles. In these applications, underfill materials are employed to reinforce the interfaces between substrates and semiconductor dies to enhance the durability and reliability of Flip-Chip Ball Grid Array (FCBGA) packages. They play a crucial role in various aspects of chip manufacturing, from specialized chemical formulations to intricate manufacturing tools and vital infrastructure. Due to potential health impacts, non-PFAS materials are considered as an alternative. While traditional underfill often contains PFAS, concerns about their environmental persistence and potential health effects have cast a shadow over their continued use. Recognizing this, the semiconductor industry is determined to find robust, non-PFAS alternatives. While existing studies on packages explore the effects of temperature on full FCBGA packages, a critical knowledge gap remains regarding the interfacial reliability of chip/underfill (UF) interfaces, especially with the growing demand for non-PFAs underfills and the additional complexities introduced by mechanical loads. Delamination is one of the most prevalent failure modes encountered at the chip/underfill (UF) interfaces. When assessing the reliability of these interfaces, important parameters to consider are bulk underfill characterization and interfacial fracture toughness. The samples are subjected to humidity exposure and isothermal aging. To investigate the failure modes of non-PFAs underfills in chip/UF Interfaces, tensile tests are conducted on bulk underfill samples, and fracture toughness parameters and strain energy release rate are determined for the chip/UF interfaces.
Hygrothermal Aging Evolution of Non-PFAS FCBGA Interfaces
Authors: Lall Pradeep , Choudhury Padmanava , Pandurangan Aathi , Kasturi Madhu 
Published: November 2024

Abstract
Per-polyfluoroalkyl substances, also known as forever chemicals, have uniquely useful characteristics that have made them ubiquitous in their use for industrial, commercial, and electronics applications, but there are several epidemiological studies linked to severe health effects such as liver diseases, thyroid malfunctions to these PFAS chemicals. A unified approach must be taken to remove these chemicals from electronics applications so that there is a minimum amount of waste generation of PFAS chemicals. Our solution is to show that non-PFAS materials have the same reliability in the end-use environment as in the case of PFAS so that the industry moves away from PFAS materials. The study aims to assess the interface between non-PFAS TIM/Copper and compare degradation properties with PFAS counterparts when subjected to high temperature and humidity end-use conditions.
Study of a brief online and group focusing intervention: a protocol for a randomised clinical trial
Authors: Aguiar Clara , Oliveira Cláudia , Monteiro Marina , Paiva Alexandra , Salgado João 
Published: November 2024

Introduction
Emotion dysregulation is a transdiagnostic characteristic that affects many people with many psychopathological problems. Two mechanisms that have been frequently associated with emotional regulation are immersion and distancing. Focusing is a task that combines these two mechanisms of emotion regulation through the phase of creating a working distance and subsequently the phase of reassigning meaning. However, the benefit of its use in Portuguese population without a moderate to severe symptomatology for promoting mental health remains unclear.

Methods and analysis
Participants aged between 18 and 65 years who wish to improve their awareness and understanding of their emotions will be recruited and then, randomised into two groups: the intervention group (IG) and the control group (CG; delayed intervention). The IG will have access to two focusing sessions and the CG will only have access to the intervention 4 weeks later. Both groups will be evaluated at five different times. Primary outcomes include positive and negative affect, attitudes towards focusing (emotions and bodily sensations), the ability to perform focusing and emotion regulation. Secondary outcomes include mental health and psychological well-being, depression and anxiety symptoms and self-esteem.

Ethics and dissemination
Our study has been approved by the Council of Ethics and Deontology of the University of Maia. Findings will be disseminated via manuscripts, presentations and the lead author’s thesis.

Trial registration number

NCT16974329
.