bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow and Thermal Resistance Network Modeling of Finned Heat Sinks With Bypass Mounted in Rectangular Enclosure
Authors: Fukada Masaya , Fukue Takashi , Sugimoto Yasuhiro , Hatakeyama Tomoyuki , Ishizuka Masaru 
Published: November 2021

Abstract
This study describes a thermal design method of forced convection cooling in high-density packaging electronic equipment for upstream design processes by flow and thermal resistance network analysis. Forced convection cooling by combining fans and heat sinks is the most standard strategy for dissipating heat from electronic equipment. In recent years, the thermal design of electronic equipment becomes more critical, and fast thermal design is required due to the rapid development of final products. We have been developing the flow and thermal resistance network analysis as the quick thermal design method for electronic equipment. However, an accurate prediction of forced convection cooling performance by finned heat sinks mounted in high-density packaging electronic equipment is generally tricky. Some bypasses, which are clearances between the heat sinks and enclosure walls or other components, exist around the heat sinks. Therefore, a flow rate distribution between the heat sink fins and the bypasses should be predicted. Many researchers have investigated hydrodynamic characteristics and heat transfer characteristics of finned heat sinks. However, many previous studies have been conducted on the finned heat sink performance when there are no bypasses. In order to achieve an optimum design of the finned heat sinks in the upstream configuration regardless of the heat sink dimensions, a systematic database of hydrodynamic characteristics and heat transfer characteristics of the finned heat sinks with bypasses should be investigated.
This paper discusses the development of function models of pressure drop, flow rate distribution, and heat transfer of the finned heat sinks with the bypasses for the resistance network analysis through experiments and CFD analysis. Several types of finned heat sinks with 40 mm in width and 80 mm in length were prepared, and these were mounted in a rectangular enclosure with 45 mm in width and height. First, the pressure drop characteristic around the heat sink was investigated. In addition, the flow rate distribution between the heat sink and the bypass was evaluated separately.
A flow branching coefficient was developed to predict the flow rate distribution around the heat sink combined with the pressure drop coefficient. Using the developed flow branching coefficient, the flow and thermal resistance network model around the finned heat sink was developed. The results from the proposed resistance network model showed good agreement with those from the experiment.
Efficient Thermal Analysis of Lab-Grown Diamond Heat Spreaders
Authors: Yuan Zihao , Zhang Tao , Van Duren Jeroen , Coskun Ayse K. 
Published: November 2021

Abstract
Lab-grown diamond heat spreaders are becoming attractive solutions compared to traditional copper heat spreaders due to their high thermal conductivity, the ability to directly bond them on silicon, and allow for an ultra-thin silicon layer. Researchers have developed various thermal models and prototypes of lab-grown diamond heat spreaders to evaluate their cooling performance and heat spreading ability. The majority of existing thermal models are built using finite-element method (FEM) based simulators such as COMSOL and ANSYS. However, such commercial simulators are computationally expensive and lead to long solution times along with large memory requirements. These limitations make commercial simulators unsuitable for evaluating numerous design alternatives or runtime scenarios for real-world high-performance processors. Because of this modeling challenge, none of the existing works have evaluated the thermal behavior of lab-grown diamond heat spreaders on real-world high-performance processors running realistic application benchmarks. Recently, we have developed a parallel compact thermal simulator, PACT, that is able to carry out fast and accurate steady-state and transient thermal simulations and can be extended to support emerging integration and cooling technologies. In this paper, we use PACT to evaluate the steady-state and transient cooling performance of lab-grown diamond heat spreaders against traditional copper heat spreaders on various real-world high-performance processors (e.g., Intel i7 6950X, IBM Power9, and PicoSoC). By using PACT with architectural performance and power simulators such as Sniper and McPAT, we are able to run transient simulations with realistic benchmarks. Simulation results show that lab-grown diamond heat spreaders achieve maximum temperature and thermal gradient reductions of up to 26.73 °C and 13.75 °C when compared to traditional copper heat spreaders, respectively. The maximum steady-state and transient simulation times of PACT for the real-world high-performance chips and realistic applications used in our experiments are 259 s and 22 min, respectively.
Performance and Durability Validation of Voltage Blocking Technologies to Enable Direct Cooled High-Voltage, High-Power Modules
Authors: Iradukunda Ange-Christian , Huitink David , Gebrael Tarek , Miljkovic Nenad 
Published: November 2021

Abstract
Power densification and rising module heat losses cannot be managed by traditional “external-to-case” cooling solutions. This is especially pronounced in high voltage systems, where intervening layers of insulating material between the power devices and cooling solution need to be sufficiently thick to provide adequate voltage isolation. As operating voltages increase, the required thicknesses for these insulating layers become so large that they limit the ability to extract the heat. A direct cooling approach that addresses voltage separation issues represents a unique opportunity to deliver coolant to the hottest regions, while opening up the opportunity for increased scaling of power electronics modules. However technical concerns about long-term performance of coolants and their voltage isolation characteristics coupled with integration challenges impede adoption. Here, the reliability and performance of voltage blocking strategies, namely dielectric fluids and dielectric surface coatings, are examined to advance the feasibility of a direct cooling approach for improved thermal management of high-voltage, high-power module. The breakdown voltage of the dielectric fluid is characterized through relevant temperatures, flow, and electric fields with the ultimate goal of developing design rules for direct integrated cooling schemes. The development and electrical characterization of conformal dielectric surface coatings to provide further protection of the electronics is also undertaken. Results showed the ability for layers of Parylene C to maintain their insulating capacity when subject to E-fields as high as 33.5V/μm.
Ultra-High-Density Interconnect Enabled by Hybrid Bonding for Heterogeneous Integration: Interfacial Characteristics
Authors: Lu Mei-Chien 
Published: November 2021

Abstract
Hybrid bonding has been explored for more than a decade and implemented recently in high volume production at wafer-to-wafer level for image sensor applications to enable high performance chip-stacking architectures with ultra-high-density chip-to-chip interconnect. The feasibility of sub-micron hybrid bond pitch leading to ultra-high-density chip-to-chip interconnect has been demonstrated due to the elimination of solder bridging issues from microbump method. Hybrid bonding has also been actively considered for logic and memory chip-stacking, chiplets, and heterogeneous integration in general but encountering additional challenges for bonding at die-to-wafer or die-to-die level. Overlay precision, throughput, wafer dicing are among the main causes. Widening the process margin against overlay error by designing innovative hybrid bonding pad structure is highly desirable. This work proposes a method to evaluate these hybrid bonding pad structure designs and to assess the potential performance metrics by analyzing interfacial characteristics at design phase. The bonding areas and ratios of copper-copper, copper-dielectric, and dielectric-dielectric are the proposed key parameters. The correlation between bonding area ratios and overlay errors can provide insights on the sensitivity to process margins. Nonetheless, the impact of copper recess or protrusion associated with bonding area ratios are also highlighted. The proposed method is demonstrated by examining and analyzing the hybrid bonding pad structure design concepts from a few cases reported in literatures as examples. Concerns are identified for elaboration in future designs and optimizations.
Thermal Performance of Modular Microconvective Heat Sinks for Multi-Die Processor Assemblies
Authors: May Chris , Mizerak Jordan , Earley David , Malouin Bernard 
Published: November 2021

Abstract
As processors continually seek greater computational output, the traditional single die processor configuration is giving way to emerging multi-die processor assemblies. As a result, dies of varying powers are spatially distributed in processor packages, causing local areas of high heat density and non-uniform temperature patterns. If not properly addressed, local hot spots may limit the total device operating power, increase leakage current to lower processor efficiency, and accelerate thermal induced semiconductor deterioration to reduce device lifetime.
In this article, a modular microconvective heat sink (M2HS) is developed as a high effectiveness, high flexibility cooling solution for multi-die assemblies. Microconvective cooling, featuring optimized single-phase impingement cooling and effluent fluid flow control, provides high power density heat removal from localized heat flux zones on semiconductor dies. An AMD Threadripper 3960X is chosen as a multi-die test vehicle for the M2HS to test thermal performance in a liquid cooled experimental flow loop. Experimental results in overclocked thermal stress tests are presented, achieving power draws of up to 75% higher than the nominal processor TDP. Further, compared to a recommended product pairing of the CPU serving as a baseline heat sink, the M2HS showed a 51% improvement in CPU power draw performance. When operating at nominal, non-overclocked conditions, reduced temperature operation of the CPU using M2HS solutions resulted in a CPU efficiency increase of up to 10% compared to the baseline heat sink, providing opportunities for reduced PUE in large scale data centers. The study concludes that the M2HS shows promise as a high effectiveness, implementation-friendly cooling solution for emerging multi-die processor assemblies.
Prognostics and RUL Estimations of SAC305, SAC105 and SnAg Solders Under Temperature and Vibration Using Long Short-Term Memory (LSTM) Deep Learning
Authors: Lall Pradeep , Thomas Tony , Blecker Ken 
Published: November 2021

Abstract
Prognostics and Remaining Useful Life (RUL) estimations of complex systems are essential to operational safety, increased efficiency, and help to schedule maintenance proactively. Modeling the remaining useful life of a system with many complexities is possible with the rapid development in the field of deep learning as a computational technique for failure prediction. Deep learning can adapt to multivariate parameters complex and nonlinear behavior, which is difficult using traditional time-series models for forecasting and prediction purposes. In this paper, a deep learning approach based on Long Short-Term Memory (LSTM) network is used to predict the remaining useful life of the PCB at different conditions of temperature and vibration. This technique can identify the different underlying patterns in the time series that can predict the RUL. This study involves feature vector identification and RUL estimations for SAC305, SAC105, and Tin Lead solder PCBs under different vibration levels and temperature conditions. The acceleration levels of vibration are fixed at 5g and 10g, while the temperature levels are 55°C and 100°C. The test board is a multilayer FR4 configuration with JEDEC standard dimensions consists of twelve packages arranged in a rectangular pattern. Strain signals are acquired from the backside of the PCB at symmetric locations to identify the failure of all the packages during vibration. The strain signals are resistance values that are acquired simultaneously during the experiment until the failure of most of the packages on the board. The feature vectors are identified from statistical analysis on the strain signals frequency and instantaneous frequency components. The principal component analysis is used as a data reduction technique to identify the different patterns produced from the four strain signals with failures of the packages during vibration. LSTM deep learning method is used to model the RUL of the packages at different individual operating conditions of vibration for all three solder materials involved in this study. A combined model for RUL prediction for a material that can take care of the changes in the operating conditions is also modeled for each material.
Repeatability and Extended Time Stability Study of an Additively Printed Strain Gauge Under Different Load Conditions
Authors: Lall Pradeep , Narangaparambil Jinesh , Thomas Tony , Schulze Kyle 
Published: November 2021

Abstract
Printed electronics has found new applications in wearable electronics owing to the opportunities for integration, and the ability of sustaining folding, flexing and twisting. Continuous monitoring necessitates the production of sensors, which include temperature, humidity, sweat, and strain sensors. In this paper, a process study was performed on the FR4 board while taking into account multiple printing parameters for the direct-write system. The process parameters include ink pressure, print speed, and stand-off height, as well as their effect on the trace profile and print consistency using white light interferometry analysis. The printed traces have also been studied for different sintering conditions while keeping the FR4 board’s temperature limit in mind. The paper also discusses the effect of sintering conditions on mechanical and electrical properties, specifically shear load to failure and resistivity. The data from this was then used to print strain gauges and compared them to commercially available strain gauges. By reporting the gauge factor, the printed strain gauge has been standardized. The conductive ink’s strain sensing capabilities will be studied under tensile cyclic loading (3-point bending) at various strain rates and maximum strains. Long-term performance testing will be carried out using cyclic tensile loads.
‘You just prefer to die early!’: how socioecological context impedes treatment for people living with HIV in Iran
Authors: Ameli Vira , Taj Leila , Barlow Jane , Sabin Lora , Meinck Franziska , Haberer Jessica , Mohraz Minoo 
Published: November 2021

IntroductionDespite the low prevalence of HIV and broad provision of antiretroviral therapy, the Middle East and North Africa (MENA) remains the only region where new HIV infections and AIDS-related deaths are not declining. There is a dearth of evidence from MENA on antiretroviral therapy engagement. In this qualitative study, we sought to identify the ways in which successful treatment is hindered in Iran, which is home to 24% of HIV infections in MENA.MethodsFrom August 2018 to January 2019, we used purposive sampling and conducted 12 individual interviews and 8 focus group discussions with 27 female and 31 male patients, in addition to 5 individual interviews with HIV care providers and 1 focus group discussion with 8 care providers. Social constructivism augmented with realist-informed thematic analysis was used to understand how the socioecological context triggers cognitive and affective mechanisms that disrupt antiretroviral therapy.ResultsThe use of Thematic Network Analysis resulted in the identification of three key cognitive and affective mechanisms that appear to shape treatment experience and are triggered via HIV’s socioecological context and changing economic conditions in Iran: denial in response to societal negative perceptions of HIV; fear in response to societal lack of awareness regarding HIV and misinformation; and despair in response to HIV-related stigma and enacted discrimination, economic insecurity and social support.ConclusionsTo our knowledge, this is the first study within MENA to identify pathways through which successful treatment is hindered. It appears that lack of societal awareness regarding HIV is specific to low prevalence settings, such as MENA countries, where negative perceptions, stigma, discrimination and misinformation regarding HIV and its treatment produce denial, fear and despair, acting as mechanisms that disrupt antiretroviral therapy. The experience of despair, in response to changing economic conditions and social support, further impacts treatment experience.
Application of Multi-Criteria Decision-Making Methods in Sustainable Manufacturing Management: A Systematic Literature Review and Analysis of the Prospects
Authors: Pelissari Renata , Khan Sharfuddin Ahmed , Ben-Amor Sarah 
Published: November 2021

Due to increasing environmental regulation and customers’ demand for environmentally friendly products, organizations have been required to adopt sustainable manufacturing practices by implementing clean technology (Cleantec) to manufacture green products. By adopting environmental practices, organizations can also achieve qualitative and quantitative benefits that help them remain competitive in the market while meeting governmental environmental policies, such as lowering energy and the cost of materials. The significant number of articles addressing sustainability in manufacturing published in the past few years attests to the importance of the topic. However, not many studies have been developed to understand the decision-making process in sustainable manufacturing. Therefore, the objective of this paper is to conduct a systematic literature review on the application of multi-attribute decision-making (MADM) methods in sustainable manufacturing. A total of 158 papers, published between 2009 and 2018, met the criteria set in the research methodology. The 158 papers were then analyzed and classified into seven categories: (i) SM domain, (ii) activity within the organization, (iii) decision goals, (iv) decision-makers involved (group or individual), (v) uncertain data, (vi) SM aspects (social, environmental, and economic), and (vii) MADM methods. Among the results, we identified that AHP is the most applied MADM method and, regarding the activities of the organization, MADM methods have been the most frequently applied to strategy management and supply chain. We also identified a tendency to consider uncertain and imprecise data in the decision-making process. Another result is that all the three domains — economic, environmental and social — were considered in most of the papers, followed by the combination of the economic and environmental perspectives. In the conclusion, some recent trends and future research directions are highlighted.
Cosmological scenario in κ(R,T) gravity
Authors: Dixit Archana , Pradhan Anirudh , Chaubey Raghavendra 
Published: November 2021

In this paper, we investigate the cosmic acceleration and the behavior of dark energy (DE) in the structure of the recently proposed [Formula: see text] gravity theory [G. R. P. Teruel, [Formula: see text] gravity, Eur. Phys. J. C 78 (2018) 660]. In this study, we obtained some fascinating cosmological features that are coherent with observational evidences and the touchstone [Formula: see text]CDM model. To find the deterministic solution, we consider a periodic deceleration parameter [Formula: see text], where [Formula: see text] [M. Shen and L. Zhao, Oscillating quintom model with time periodic varying deceleration parameter, Chin. Phys. Lett. 31 (2014) 010401], which predicts the decelerating and accelerating phases of the universe. The Equation of State (EoS) parameter also supports the idea of DE, which is the dominant component and it is responsible for the universe’s accelerated expansion. Here, we also construct cosmographic parameters, like, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and studied their evolution in spatially flat [Formula: see text] gravity. We find that these observations are sufficient in comparison with the universe’s physical and kinematic properties and also consistent with ongoing (OHD[Formula: see text][Formula: see text][Formula: see text]JLA) observation. Next, we apply the geometric diagnostics, the state-finder ([Formula: see text]) in [Formula: see text] gravity to discriminate from the [Formula: see text]CDM model. We found that our model lies in quintessence and the Chaplygin Gas region. Finally, the model approaches [Formula: see text]CDM at the present epoch of the universe.
PGC1α Regulates the Endothelial Response to Fluid Shear Stress via Telomerase Reverse Transcriptase Control of Heme Oxygenase-1
Authors: Kant Shashi , Tran Khanh-Van , Kvandova Miroslava , Caliz Amada D. , Yoo Hyung-Jin , Learnard Heather , Dolan Ana C. , Craige Siobhan M. , Hall Joshua D. , Jiménez Juan M. , St. Hilaire Cynthia , Schulz Eberhard , Kröller-Schön Swenja , Keaney John F. 
Published: November 2021

Objective:
Fluid shear stress (FSS) is known to mediate multiple phenotypic changes in the endothelium. Laminar FSS (undisturbed flow) is known to promote endothelial alignment to flow, which is key to stabilizing the endothelium and rendering it resistant to atherosclerosis and thrombosis. The molecular pathways responsible for endothelial responses to FSS are only partially understood. In this study, we determine the role of PGC1α (peroxisome proliferator gamma coactivator-1α)-TERT (telomerase reverse transcriptase)-HMOX1 (heme oxygenase-1) during shear stress in vitro and in vivo.

Approach and Results:

Here, we have identified PGC1α as a flow-responsive gene required for endothelial flow alignment in vitro and in vivo. Compared with oscillatory FSS (disturbed flow) or static conditions, laminar FSS (undisturbed flow) showed increased PGC1α expression and its transcriptional coactivation. PGC1α was required for laminar FSS-induced expression of TERT in vitro and in vivo via its association with ERRα(estrogen-related receptor alpha) and KLF (Kruppel-like factor)-4 on the
TERT
promoter. We found that TERT inhibition attenuated endothelial flow alignment, elongation, and nuclear polarization in response to laminar FSS in vitro and in vivo. Among the flow-responsive genes sensitive to TERT status, HMOX1 was required for endothelial alignment to laminar FSS.

Conclusions:
These data suggest an important role for a PGC1α-TERT-HMOX1 axis in the endothelial stabilization response to laminar FSS.