bluuebunny/crossref_metadata_2025 huggingface dataset:
How Do We Believe?
Authors: Sloman Steven A.
Published: November 2021

My first 30‐odd years of research in cognitive science has been driven by an attempt to balance two facts about human thought that seem incompatible and two corresponding ways of understanding information processing. The facts are that, on one hand, human memories serve as sophisticated pattern recognition devices with great flexibility and an ability to generalize and predict as long as circumstances remain sufficiently familiar. On the other hand, we are capable of deploying an enormous variety of representational schemes that map closely onto articulable structure in the world and that support explanation even in unfamiliar circumstances. The contrasting ways of modeling such processes involve, first, more and more sophisticated associative models that capture progressively higher‐order statistical structure and, second, more powerful representational languages for other sorts of structure, especially compositional and causal structure. My efforts to rectify these forces have taken me from the study of memory to induction and category knowledge to causal reasoning. In the process, I have consistently appealed to dual systems of thinking. I have come to realize that a key reason for our success as cognizers is that we rely on others for most of our information processing needs; we live in a community of knowledge. We make use of others both intuitively—by outsourcing much of our thinking without knowing we are doing it—and by deliberating with others.
An aggressive CD4−CD8− T‐cell neoplasm in young English bulldogs
Authors: Frankhouse Kari A. , Rout Emily D. , Hughes Kelly L. , Labadie Julia D. , Yoshimoto Janna A. , Lana Susan E. , Avery Paul R. , Avery Anne C.
Published: November 2021

T‐cell leukemia/lymphoma accounts for roughly 30% of all types of lymphoproliferative neoplasia in dogs. Two forms of T‐cell lymphoma (T‐zone and peripheral T‐cell lymphoma) exhibit breed‐specific predilections. During the course of routine immunophenotyping, we observed a breed‐specific presentation of a unique form of T‐cell leukaemia in young English bulldogs. To describe the clinical presentation and outcome of a novel T‐cell leukaemia in English bulldogs and determine the frequency of this neoplasm in other breeds. The Clinical Hematopathology database, containing immunophenotyping data from peripheral blood of nearly 11 900 dogs, was queried for the phenotype observed in young English bulldogs: CD45+CD4−CD8−CD5+CD3+ class II major histocompatibility complex (MHC)‐low T‐cell leukaemia. Clinical presentation, treatment, and survival data were collected for a subset of cases. Fifty‐five English bulldog cases and 64 cases of other breeds were identified. No other breed was represented by >5 cases. Complete medical records were obtained for 50 bulldogs. Median age at diagnosis was 3 years and 76% of cases were male. Median lymphocyte count was 44 286 lymphocytes/μl (range, 1800–317 684/μl) and lymphocytes were described as small to intermediate‐sized. Many dogs were thrombocytopenic and had liver and spleen involvement, but not lymphadenopathy. Bulldogs that received multi‐agent chemotherapy had longer median survival times (83 days) compared to dogs that received no treatment (6 days) or less aggressive therapy (15 days) (p = .001). Non‐bulldogs had similar outcomes. CD4−CD8− class II MHC‐low T‐cell leukaemia has an aggressive clinical course and predilection for young English bulldogs. Breed‐specific presentation suggests an underlying genetic cause.
Living mulch persistence in an apple orchard and its effect on the weed flora in temperate climatic conditions
Authors: Żelazny Wiktor Rafał , Licznar‐Małańczuk Maria
Published: November 2021

Replacing herbicide fallow with alternative floor management can conserve soil and reduce agrochemical use in an orchard. Increased perennial weed resistance to foliar preparations has recently become an additional motivation to abandon herbicides. This study explores apple tree understory weed flora alteration after introducingFestuca ovinaliving mulch to the rows. Delayed cover crop sowing was tested as a possible approach to address the problem of high perennial weed dominance when a living mulch is introduced in the year of orchard establishment, in addition to reducing competition. The effect of replacing the M.9 dwarfing rootstock with the M.26 and P 60 semi‐dwarfing rootstocks to foster tree competitiveness was also investigated, and the influence of the mulch dominance on apple yield was analysed. Abundant perennial weed flora developed in the living mulch regardless of the mitigation strategy, and one of the cover crop cohorts exhibited unsatisfactory persistence when maintained under trees on P 60. This pattern was attributed to an interactive effect of shadowing by the more vigorous trees and byGlechoma hederaceaandArtemisia vulgarisweeds, which abounded due to insufficient mowing frequency. More intensive tree understory management is recommended, especially in semi‐dwarf orchards, andG. hederaceashould be studied more as a candidate mulch species, potentially superior toF. ovina.
Roof Deformation and Collapse of Stamps With Isolated Grooves: A Contact Mechanics Approach
Authors: Jin Fan , Tang Changyu , Guo Xu , Bai Longteng
Published: November 2021

This paper has revisited the roof deformation and collapse of stamps with isolated grooves based on a contact mechanics approach, with emphasis on establishing the nonadhesive and adhesive contact solutions for surfaces containing a shallow rectangular groove with the effects of applied load and interfacial adhesion taken into account. By solving singular integral equations and using the energy release rate approach, closed-form solutions are derived analytically for the deformed groove shapes, interfacial stress distributions, and equilibrium relations between load and contact size, which reduce to the previously proposed solutions without adhesion or without applied load. Finite element (FE) analysis is performed to validate the nonadhesion solutions, while experiment results of stamp collapse reported in the literature are adopted to examine the adhesion solutions. By introducing the Johnson parameter α to represent a competition between surface energy and elastic strain energy of the groove, four kinds of contact behaviors of the groove roof can be characterized appropriately: nonadhesion, weak adhesion, intermediate adhesion, and strong adhesion. Hysteresis loop and energy loss due to distinct load/unloading paths are revealed in the cases of intermediate and strong adhesion. We have also provided the critical applied pressure to achieve roof collapse and the corresponding equilibrium contact size for full range of α.
Design, analysis and test of a novel cylinder-driven mode applied to microgripper
Authors: Chen Xiaodong , Xie ZM , Tan Huifeng
Published: November 2021

How to enlarge the output displacement is a key issue in the research field of microgrippers. It is difficult to further enlarge the output displacement for the traditional displacement transmission mechanism (DTM). In this research, a two-stage amplification cylinder-driven DTM based on the compliant mechanisms is designed to realize the displacement output expansion. The opening and closing of the clamping jaws is driven by the air cylinder to enlarge the output displacement of the microgripper. According to the analysis of statics model of the mechanism, the relationship between the output displacement of the microgripper and the driving pressure of the cylinder is established. The magnification of the microgripper is obtained using a dynamic model. Moreover, based on the finite element analysis, the mechanical structure parameters are optimized. The microgripper was fabricated by utilizing wire electro discharge machining (WEDM) technique, and then a series of experiments were carried out to obtain the relationship between the displacement and the driving pressure. It is found that the maximum output displacement measured is 1190.4μm under the pressure of 0-0.6 Mpa, corresponding to the magnification of 47.63. Compared with the results of finite element analysis and theoretical calculation, the test results have a discrepancy of 2.39% and 6.62%, respectively. The microgripper has successfully grasped a variety of micro-parts with irregular shapes, and parallel grasping can be achieved, demonstrating the potential application of this design in the field of micromanipulation.
Confined Transducer Geometries to Enhance Sensitivity to Thermal Boundary Conductance in Frequency-Domain Thermoreflectance Measurements
Authors: Warzoha Ronald J. , Wilson Adam A. , Donovan Brian F. , Clark Andy , Cheng Xuemei , An Lu , Lee Ezra , Liu Xiaosong , Feng Gang
Published: November 2021

Quantifying the resistance to heat flow across well-bonded, planar interfaces is critical in modern electronics packaging architectures, particularly as device length scales are reduced and power demands continue to grow unabated. However, very few experimental techniques are capable of measuring the thermal resistance across such interfaces due to limitations in the required measurement resolution provided by the characterization technique (i.e., Rth < 0.1 mm2·K/W in steady-state configurations) and restrictions on the thermal penetration depth that can be achieved as a result of the heating event that is typically imposed on a sample’s surface (for optical pump-probe thermoreflectance techniques). A recent numerical fitting routine for Frequency-domain Thermoreflectance (FDTR) developed by the authors1 offers a potential avenue to rectify these issues if the transducer’s geometry can be confined. This work utilizes numerical simulations to evaluate the sensitivity of FDTR to a range of thermal boundary resistance (TBR) values as a function of the thermal resistance of adjacent material layers. Experimental measurements are performed across a handful of different material systems to validate our computational results and to demonstrate the the extent to which confined transducer geometries can improve our sensitivyt to the TBR across so-called “buried” interfaces when characterized with FDTR.
Experimental Investigation of Boiling Heat Transfer in a Liquid Chamber With Partially Soluble Nanofluids
Authors: Unno Noriyuki , Yuki Kazuhisa , Kibushi Risako , Nogita Rika , Mitani Atsuyuki
Published: November 2021

Boiling heat transfer (BHT) is a promising technique to remove a high heat flux emitted from next-generation electronic devices. However, critical heat flux (CHF) is a big problem in BHT because it restricts the maximum performance of the cooling devices using BHT. Nanofluid has been widely used to improve the CHF. In this study, the authors investigated the BHT of a compact cooling device at low pressure using a special nanofluid: that is made with partially soluble particles in water. The experimental result found that the CHF with the special nanofluid is 170 W/cm2 and is higher than that with nanofluid made with an insoluble nanoparticle.
Hotspot Cooling Performance for Submerged Confined Two-Phase Jet Impingement Cooling
Authors: Chowdhury Tanvir Ahmed , Putnam Shawn A.
Published: November 2021

Jet impingement can be particularly effective for removing high heat fluxes from local hotspots. Two-phase jet impingement cooling combines the advantage of both the nucleate boiling heat transfer with the single-phase sensible cooling. This study investigates two-phase submerged jet impingement cooling of local hotspots generated by a diode laser in a 100 nm thick Hafnium (Hf) thin-film on glass. The jet/nozzle diameter is ∼1.2 mm and the normal distance between the nozzle outlet and the heated surface is ∼3.2 mm. Novec 7100 is used as the coolant and the Reynolds numbers at the jet nozzle outlet range from 250 to 5000. The hotspot area is ∼ 0.06 mm2 and the applied hotspot-to-jet heat flux ranges from 20 W/cm2 to 220 W/cm2. This heat flux range facilitates studies of both the single-phase and two-phase heat transport mechanisms for heat fluxes up to critical heat flux (CHF). The temporal evolution of the temperature distribution of the laser heated surface is measured using infrared (IR) thermometry. This study also investigates the nucleate boiling regime as a function of the distance between the hotspot center and the jet stagnation point. For example, when the hotspot center and the jet are co-aligned (x/D = 0), the CHF is found to be ∼ 177 W/cm2 at Re ∼ 5000 with a corresponding heat transfer coefficient of ∼58 kW/m2.K. While the CHF is ∼ 130 W/cm2 at Re ∼ 5000 with a jet-to-hotspot offset of x/D ≈ 4.2.
CFD - Based Investigation of Effects of Obstruction in Front of Small Axial Cooling Fan and Deterioration of Supply Flow Rate
Authors: Fukuda Tetsushi , Masuda Yukio , Fukue Takashi , Sugimoto Yasuhiro , Hatakeyama Tomoyuki , Ishizuka Masaru , Koizumi Katsuhiro
Published: November 2021

This study describes the deterioration of a small axial fan’s supply flow rate in high-density packaging electronic equipment. A cooling fan flow rate can be predicted by its P-Q curve, which shows a relationship between a pressure rise at a fan (ΔP) and a supply flow rate (Q). However, in high-density packaging electronic equipment, the fan performance is affected by the mounting components around the fans, and the accurate prediction of the supply flow rate becomes difficult. This paper tried to do flow visualization around a small axial cooling fan’s impellers when the obstruction was mounted in front of the fan through CFD analysis. A relationship between the supply flow rate by the fan and the flow pattern around the impellers was investigated while changing the distance between the test fan and the obstruction. Through this study, the following results can be obtained. The fan’s flow is stable in the rotating stall region and the higher flow rate operating points regardless of whether or without the obstruction. At the lower flow rate conditions, the formation of a complex unsteady flow is reproduced. As the flow rate decreases, the flow’s separation point becomes closer to the leading edge of the impeller. In the case of obstruction, the change of the flow pattern causes a larger attack angle. As a result, fan performance is degraded.
Measuring the Thermal Contact Resistance Between Cu Foams and Substrates for On-Chip Cooling Applications in Data Centers
Authors: Arrivo Lucas , Schon Steven , Wemhoff Aaron P.
Published: November 2021

Data centers housing high performance computing equipment have large and growing rack densities, which pushes the limits of traditional air cooling technologies because of limited heat transfer coefficients. Therefore, on-chip cooling using so-called cold plates is emerging as a necessary cooling option for high-density electronics. The use of mini-channels or pins fins to enhance internal heat transfer area inside cold plates requires extensive micro-machining that is relatively time consuming and expensive for mass production. As an alternative approach, inserting and bonding pre-manufactured metal foams into hollow bodies are explored as a potentially inexpensive means to enhance the interior heat transfer area of cold plates. One key aspect of the performance of metal foams in cold plates is the thermal contact resistance in the bonding between the foam and the substrate. This project predicts the contact resistance using measurements of different foam types (pure Cu and Cu with oxide), porosities (63%, 80%, 93%, and 95%) and thicknesses (4 mm, 8 mm, and 10 mm). These measurements are carried out with and without the use of thermal interface material (TIM) pads. A theory is proposed and implemented to estimate the contact and foam thermal resistances, but further work is needed to gain confidence in the results. Observations suggest that different thermal behavior is seen for the Cu foams compared to the Cu with oxide foams, and that the use of TIM pads can achieve 10x to 40x reduction in overall thermal resistance for highly porous foams bonded on Cu substrates.
Temperature Cycling Study of Aerosol-Jet Printed Conductive Silver Traces in Printed Electronics
Authors: Zhao Beihan , Riso Christopher , Leslie David , Dasgupta Abhijit , Das Siddhartha , Fleischer Jason , Hines Daniel
Published: November 2021

Aerosol-Jet Printing (AJP) provides a new method for electronic component manufacturing. Understanding the reliability of electronics printed using the AJP process is essential to take full advantage of this technology and realize its industrial potential.

In the current study, we have designed and tested AJP printed samples and conducted failure analysis of those samples that have exhibited early failures. Failures first occurred in the short traces that connect the main traces to the silver pads, due to local stress-raisers caused by local geometric features in the printing geometry. Thermal-Mechanical Finite-Element-Modeling (FEM) has been performed to analyze the cyclic history of thermo-mechanical stress distribution and plastic strain distribution.
Transient Performance and Melt Front Characterization of Phase Change Materials
Authors: Stamps Tyler , Huitink David
Published: November 2021

Thermal management systems are often over-designed for average use in order to handle spikes in heat generation, which increases the spatial and financial requirements. One way to mitigate this is via the use of phase change materials (PCMs) as thermal buffers and storage media. This paper examines the melt front behavior of a common solid to liquid PCM, paraffin, experimentally and numerically. A 16 cm3 fully enclosed melting chamber was designed and constructed to observe the melt behavior via IR imaging. The chamber applies a constant temperature heat flux to one end of the sample and a constant temperature cold boundary on the other. ARL ParaPower was used for the numerical simulation. This tool models the convection in liquid PCM as an effective thermal conductivity parameter. The MATLAB-based program offers faster computation times than high fidelity commercial FEA tools. The experimental and numerical data are then compared via a custom MATLAB script which identifies the melt front and outputs the position and velocity over time for each test case. It was concluded that ParaPower adequately depicts the melt front behavior under this set of experimental conditions. This work enables future studies using the IR-transparent melt chamber designed herein.
A Hybrid Microporous Copper Structure for High Performance Capillary-Driven Liquid Film Boiling
Authors: Soroush Farid , Liu Tanya , Wu Qianying , Zhang Chi , Asheghi Mehdi , Goodson Kenneth E. , Marco Lorenz , Christian Egger , Martin Rittner
Published: November 2021

Phase change thermal management devices including heat pipes and ultra-thin vapor chambers can remove and spread the excess heat from microprocessors more efficiently compared with the conventional heat sinks. However, the capillary and CHF limits of the evaporator section remained a challenge for high heat flux (> 100 Wcm−2) large area (> 5 × 5 mm2) applications. In this study, a hybrid microporous structure consists of copper wire meshes (CWMs) as the liquid delivery routing and copper inverse opals (CIOs) film as the boiling/evaporation platform is proposed. The feasibility of the approach and the design optimization were studied with extensive modeling and CFD simulations. For the experiment setup, the heater and the RTD sensors are fabricated over a Silicon chip using the conventional micro fabrication processes and the micro porous copper film is deposited based on template-assisted electrodeposition, resulting in CIOs structure with average 5 μm pore size, 1 μm neck, and 15 μm thickness. A copper wire mesh structure (500 μm thickness, 0.5 porosity, 71 μm wire diameter) with 4 × 4 tile openings (1 × 1 mm2 area per tile) was fixed over the CIOs film with mechanical constraints. A flow loop and vapor chamber are designed and fabricated to perform capillary boiling experiments in a saturated environment (liquid water and vapor at ∼100°C). The hybrid microporous structure was able to remove over 75 W from the 5 × 5 mm2 heater area (over 300 W cm−2 heat flux) with 9°C super heat resulting in thermal resistance of 0.03 cm2°CW−1 at the CHF. The findings of this study are largely beneficial for the design and fabrication of high performance evaporator wicks and next-generation heat routing technologies.
Reliable Additive Manufacturing Using Transient Liquid Phase Sintering
Authors: Nave Gilad , Buxbaum Clifton , McCluskey F. Patrick
Published: November 2021

Additive manufacturing is rapidly revolutionizing the way products are designed and built. Its advantages in terms of mobile manufacturing, mass customization, part reduction, waste reduction, and just-in-time sparing are causing it to be considered for many electronics applications. Many of these applications require high thermal and electrical conductivity and high strength in harsh environments. Such applications would benefit greatly from additive manufacturing of metals. However, the number of metal systems that can be successfully manufactured this way is small, with some of the highest conductivity metals (e.g. Cu, Ag) being particularly difficult. Two ways of depositing metals dominate the market. The first is direct ink writing (DIW). The other common technique is laser sintering, including direct metal laser sintering (DMLS). While the DIW process is fine in principle, the inks typically used are not optimized for harsh applications, and produce a voided and porous layer that limits the thermal and electrical conductivity. Laser sintering must be done in vacuum and requires that the laser raise the temperature of the powder to around 500°C which can result in damage to the substrate. Furthermore, this process is expensive, lacks mobility, and consumes significant energy.

This paper will discuss a new form of metal additive manufacturing that addresses the shortcomings of current direct writing and laser sintering approaches by making use of the transient liquid phase sintering process. During the TLPS process, low melting point semimetal powder of Indium will be melted at a temperature of 300°C. This liquid will then surround and diffuse with high melting temperature metal powders forming intermetallic compounds at the solid-liquid interface. These intermetallics possess a higher melting point than the low temperature semimetal. The paper will demonstrate the use of this technique to make reliable 2D lines and 3D structures. It will also discuss the deposition and sintering process and its effect on the adhesion strength, thermal conductivity, and electrical resistivity of the resulting structures.
Enhanced Processability and Thermal Fatigue Reliability With Low Melting Point SnBi Solder Alloy LMPA-Q
Authors: Vandevelde Bart , Nawghane Chinmay , Labie Riet , Lauwaert Ralph , Werkhoven Daniel
Published: November 2021

SnBi based solder alloys become an interesting alternative for standard SnAgCu as they can be used to solder components at much lower temperature. The typically 50°C lower solder reflow temperature is less damaging for PCB and components, and also prevents hot tear and head-in-pillow failures for large fine pitch BGA components. A reasonable concern for these low-melting temperature solders is the thermal cycling reliability performance, in particular for harsh conditions such as automotive products. In this work, thermal cycling testing and failure analysis have been performed on 9 × 9 mm size QFN components and large chip components (2010 and 2512) which are typically sensitive to thermal fatigue. The results are benchmarked to standard SAC alloy. Also the process advantages from the low temperature solder alloys are depicted in this paper. Finally, the effect of Pb contamination on this SnBi based solder is investigated.
Optimizing Closed-Loop Liquid Cooling Solution for Extreme High Power Multi-Packages
Authors: Panigrahy Arunima , Subrahmanyam Prabhakar , Pang Ying-Feng , Sahan Ridvan , Xia Amy
Published: November 2021

Current technological developmental efforts for high performing liquid assisted air-cooling solution (LAAC) is presented in this research. The roadmap needs of high-power packages such as client, datacenter and graphics product segments are addressed. Systematic evaluation and qualification process for developing cost effective LAAC solutions to provide cooling capabilities for multiple socketed packages are also discussed. This effort includes qualifying high performing heat exchanger (finned radiator) and cold plate with different fin designs. Thermal simulations were conducted and correlated with experimental data. The concept of power density approach is introduced for predicting the cooling capability of newly developed LAAC solution for different lidded package form factors. The paper presents supporting data of performance evaluation from graphics segment that extends the solution capability to data center segment. The technology developed here will address the increasing cooling capability needed for future products with high power dissipation and multiple socket cooling configuration.
Microchannel Heat Sink for Thermal Management of Concentrated Photovoltaic Cells
Authors: Varghese Dinumol , Sefelnasr Ahmed , Sherif Mohsen , Alnaimat Fadi , Mathew Bobby
Published: November 2021

This article conceptualizes a single-phase microchannel heat sink for thermal management of concentrated photovoltaic cells; details of the model-based parametric study that is carried out on the heat sink is also detailed in this article. The heat sink consists of multiple serpentine microchannels. The mathematical model consists of continuity equation, Navier-Stokes equations and energy equations. Fluent module of Ansys Workbench is used for solving the model. The performance of the device is quantified in terms two metrics such as thermal resistance and pumping power. Studies are done for Reynolds number ranging from 100 to 1250. It is observed that increase in Reynolds number decreases the thermal resistance while increasing the pumping power irrespective of the geometric parameters of the heat sink. Decrease in hydraulic diameter of the microchannel reduces the thermal resistance while increasing the pumping power. Increase in the length segment of the serpentine microchannel increases and decreases the thermal resistance and pumping power, respectively. With increase in the offset width of the serpentine microchannel the thermal resistance and pumping power decreases and increases, respectively.
Reliability and SOH Degradation of Thin Li-ion Batteries Under Various Flexing Conditions
Authors: Lall Pradeep , Jang Hyesoo , Soni Ved , Miller Scott
Published: November 2021

Reliability of Li-ion batteries (LIB) is major concern for FHE devices due to needs of flexibility without degradation of state of health (SOH) of the LIB. In this regard, a thin form factor based LIB below 1mm of thickness is regarded as the candidate material to meet such needs because it is able to be fold, bent and twisted with limited performance drop. In addition to this, LIB has high specific power (W/Kg) and high specific energy (Wh/Kg) and a lower memory effect which could make the LIB more attractive for wearable applications. While studies on chemo-physical effect such as SEI growth, material decay, etc. due to repeated charging and discharging LIB has been conducted greatly, but such effects due to the flexing LIB have been rarely conducted. In this study, degradation of thin-flexible power source reliability has been studied under twist, flexing, flex-to-install of magnitude to replicate stresses of daily motion of human body using motion-control setups in a lab-environment. Additionally, AI-based regression model has been developed to predict the SOH of the battery with multiple variables including physical, ambient and chemo-mechanical experimental conditions which could be challenged to be treated by the manpower. The developed models can be used to predict the life of the battery and analyze acceleration factors between test conditions and use conditions for variety of test conditions based on the individual variables and their interactions.
Mechanical Properties of Doped Solder SAC-Q for High Strain Rate Testing at Extreme Surrounding Temperatures for 6 Months of Isothermal Aging
Authors: Lall Pradeep , Mehta Vishal , Suhling Jeff , Blecker Ken
Published: November 2021

Electronic parts may often get exposed to high strains during shocks, vibrations and drop conditions in both commercial and defense applications. In addition, such electronic parts can often be simultaneously exposed to extreme surrounding temperatures between −65°C and 200°C after storage in non-climate-controlled conditions. Electronic equipment can be subjected to strain rates of 1 to 100 per second in shock and vibration. Many of the doped SAC soldering alloys in the electronic components, including SAC-Q, SAC-R, Innolot have found applications in long-term thermal exposure environments. Low temperature high strain-rate properties are needed to assure durability under high temperature storage followed by shock and vibration. There is scarcity of high strain-rate data on alloys exposed to high temperature aging operating at extreme low-temperatures and extremely-high temperatures. For this study, SAC-Q material was tested and analyzed at temperatures from −65°C to 200°C and at a strain rates of from 10 to 75 per second. Following the production and retrieval of the specimens, specimens were stored for isothermal aging for up to 6 months at 100°C temperature, before performing tensile test experiments at various operating temperatures. Stress vs strain curves are formed for the wide range of strain rates and surrounding temperatures. In addition, test results and data were complemented by the Anand viscoplasticity model and by calculating stress-strain behavior, evaluated in a wide range of working temperatures and strains rates.
Low Temperature Material Characterization of Lead-Free SAC Solder Alloy at High Strain Rate After Prolonged High Temperature Storage
Authors: Lall Pradeep , Yadav Vikas , Suhling Jeff , Locker David
Published: November 2021

During operations, handling, and storage in extreme environmental applications including aerospace, defense and automotive, the electronics may be exposed to high and low operating temperatures. In automotive underhood applications, the temperature can vary especially from −65 to +200 °C. Under prolonged storage, SnAgCu solder materials have been shown to continually evolve in the mechanical properties. New doped SAC solder alloys have recently been introduced with the addition of Ni, Co, Au, P, Ga, Cu and Sb to SAC solder alloy to increase the robustness under prolonged thermal exposure. High strain-rate data on SAC solder alloys after prolonged storage operating at low operating temperatures is not available in published literature. In this paper, materials characterization of SAC (SAC105 and SAC-Q) solder after prolonged storage at low operating temperatures (−65°C–0 °C) and at high strain rates (10–75 per sec) has been studied. The fabricated SAC leadfree solder specimens were isothermally aged up to 12 months at 50°C before testing. Anand Viscoplastic model has been used to compute 9 anand parameters from measured Tensile data to describe the material constitutive behavior. The computed 9 anand parameters were used to verify the accuracy of the Anand model. A good correlation was found between experimental data and Anand predicted data.
Evolution of Prony Parameters for Underfills Subjected to High Temperature Long Term Aging
Authors: Lall Pradeep , Zhang Yunli , Wu Haotian , Suhling Jeff , Davis Edward
Published: November 2021

Advanced drive assist systems and support power systems reside underhood where operating temperatures are much higher than in traditional consumer applications. Temperatures in automotive underhood electronics may range from −40 °C to +150°C for long periods of time during operation. Much of the advanced functionality is enable through the use of advanced architectures including flip-chip ball-grid arrays. Underfills are used to enhance the solder joint reliability between the chip and the substrate. However, there is insufficient information about the viscoelasticity of Underfills stored in sustained high temperature for long period of time. In this paper, two different types of Underfills have been cured and aged under two different temperatures: 100 °C and 150 °C. Multi-frequency scan dynamic mechanical analyzer (DMA) test has been conducted to study the viscoelasticity evolution from pristine, 30 days, 60 days, 90 days and 120 days. The master curve has been obtained and the pony pairs of UFs have been calculated. The linear viscoelastic behavior of two kinds of Underfills as the function of aging time and aging temperature has been investigated. Elastic modulus, loss modulus and glass transition temperature are extracted from the results of dynamic loading tests. The aging effect of linear viscoelasticity has been discussed.
Solderability and Reliability of Sintered Nano-Ag Bond Pads of Printed Re-Distribution Layer (RDL)
Authors: Lee S. W. R. , Lo J. C. C. , Qiu X. , Tu N.
Published: November 2021

Re-distribution layer (RDL) is one key enabling technology for advance packaging. RDL is usually fabricated in wafer level by photolithography process. An alternative approach for implementing RDL by additive manufacturing (AM) method is proposed in this study. This allows RDL to be fabricated on singulation chip. Nano-silver (nano-Ag) ink is printed on the silicon chip to form routing traces and bond pads. However, the Ag pad may be consumed by solder quickly if the process is not properly controlled. This paper studied the effect of nano-Ag ink sintering condition on the solderability of Ag pad. The solder joint mechanical integrity was evaluated by solder ball shear test. High temperature storage test was also carried out to evaluate the solder joint reliability. Experiment results showed that Ag pad fabricated by AM is SMT compatible. High temperature storage did not cause early failure to the samples. There was not significant change in the Ag3Sn IMC layer thickness and mechanical strength. The finding of the present study will serve as a very useful reference for future practice of forming solder joints on sintered nano-Ag pads.
Comparison of CO and CO2 rf plasma treatment of SnO2 nanoparticles for gas sensing materials
Authors: Hiyoto Kimberly A. M. , Stuckert Erin P. , Fisher Ellen R.
Published: November 2021

CO and CO2 plasmas were used to modify SnO2 nanoparticles (NPs) to understand the role of key gas-phase species and to explore a potential route for improving these materials as solid-state gas sensors. Excited state species in both plasmas were monitored using optical emission spectroscopy and the NP were analyzed after plasma exposure with x-ray photoelectron spectroscopy. These studies reveal that in the CO2 plasma, CO2 decomposes to CO and O, leading to etching of the SnO2 lattice. Conversely, in the CO plasma, very little O is formed, leading to the deposition of a carbonaceous film on the SnO2 NP. Sensors fabricated with the CO2 modified SnO2 NP demonstrate a higher response to CO, benzene, and ethanol and improved response and recovery behavior when compared with untreated devices. CO plasma modification, however, had a detrimental effect on the gas sensing performance of this material.
Using static linear response theory to describe field emission field enhancement and a field-induced insulator-conductor transition
Authors: de Castro Caio P. , de Assis Thiago A. , Rivelino Roberto , Mota Fernando de B. , de Castilho Caio M. C.
Published: November 2021

Experiments on field electron emission (FE) of single carbon nanotubes (CNTs) indicate that they exhibit a nearly linear Fowler–Nordheim plot, and the field enhancement factor (FEF) near the CNT apex is independent of the applied (macroscopic) field (FM) for small radii field emitters. Recent results, based on density functional theory calculations considering CNTs with small radii, retrieved the constancy of the FEF defined in terms of the corresponding induced electron density. As a consequence, it has been reported that the constancy of the FEF with FM could be connected with the linear response of the CNT. In this paper, we reinforce this connection, considering the problem of a floating (6,6) hybrid single-walled nanotube, whose cylindrical body is an insulating one and composed of alternating boron and nitrogen atoms end-capped with carbon atoms. Our results show that the constancy of the FEF is achieved when a linear dependence between the longitudinal component of the induced system dipole moment (μi,z) and FM is observed. Two regimes of constant polarizabilities have been found at sufficiently low and high FM-values. In the intermediate range 0.3V/nm≲FM≲5 V/nm, a crossover from insulating-to-conducting behavior, exhibiting a nonlinear dependence of μi,z on FM, is found accompanied by an increase of the FEF with FM. This result reveals circumstances that could lead to dependence of the FEF on FM, being timely for interpretation of FE characteristics in the context of vacuum nanoelectronic devices.
ACOUSTICAL SOCIETY OF AMERICA Silver Medal in Signal Processing in Acoustics 2021: William S. Hodgkiss
Authors: Hodgkiss William S.
Published: November 2021

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Mitigating the toilet flush noise: A psychometric analysis of noise assessment and design of labyrinthine acoustic Meta-absorber for noise mitigation
Authors: Kumar Sanjay , Shan Chua Wei , Aow Jie Wei , Lee Heow Pueh
Published: November 2021

Modern apartments in major cities are usually made of lightweight structures with inadequate acoustic properties, leading to a growing number of noise complaints by residents of inadequate sound insulation in high-rise buildings. When a toilet is flushed, loud and irregular sounds like humming, gurgling, or bubbling, “explosive” fury from vacuum-assisted toilets are generated. Though these toilet flushing sounds are not very harmful, they can still be perceived as nuisances by users nearby. The toilet flushing noise has posed a serious concern among apartment occupants and adjacent residents, causing health problems like sleep disturbance and irritation. In this study, the psychoacoustical investigations have been performed in four stages. In the first stage, the toilet flushing noise was recorded for several toilets with two designs: a close-coupled floor-mount toilet and a back-to-wall mount toilet. The second stage evaluated the physical and psychoacoustical characteristics of those recorded flushing sounds using psychoacoustic analysis software. The noise qualities were determined in the third stage by assessing autocorrelation function/interaural cross correlation function factors from the post-processed recorded sound data. Finally, we designed and successfully demonstrated an innovative acoustic meta-absorber prototype for mitigating the toilet flushing noise. The results have revealed a significant reduction in loudness because of meta-absorbers.
Sound speed, submesoscale, and spice: The role of rapidly evolving instabilities in setting upper ocean properties
Authors: MacKinnon Jennifer
Published: November 2021

Sound speed characteristics in the upper ocean are sometimes thought to be set by a combination of mostly one-dimensional vertical mixing processes and (slow) mesoscale advection and stirring. However, a series of recent projects have showcased the role of small-scale (tens of meters to tens of km horizontally), rapidly evolving (hours to days) submesoscale instabilities in setting both stratification and sound speed properties. The observations also reveal that sound speed structure set by such processes is fundamentally three dimensional, with significant lateral gradients at a broad range of scales. Some relevant processes are frontogenetic and create sometimes rapid secondary circulations near lateral density gradients. Some are associated with wind-driven near-inertial oscillations or internal waves. Some of the more interesting recent observations concern the intersection of submesoscale and internal wave processes. Here, I will review a few highlights from the last decade of observations on unbalanced, nonlinear processes that conspire to set density, spice, and sound speed profiles in several contrasting oceans.
Mixed layers and surface ducts
Authors: Porter Michael B.
Published: November 2021

The upper ocean is strongly effected by the sun and the wind. In an idealized view, this leads to a warm mixed layer with a nearly constant temperature and salinity. Then, the increase in pressure with depth causes an increase of about 1.7 m/s in sound speed for every 100 m in depth (i.e., a gradient of 0.017/s). This gradient forms an acoustic surface duct, which is a nearly universal feature of the world’s oceans. They can be just tens of meters thick or several hundred meters in the Southern Ocean or the North Atlantic during periods of winter storms. Not surprisingly, the surface duct is very important in terms of sound propagation; However, as we shall describe, the surface duct has some peculiar acoustic properties and can produce vast shadow zones inside the duct. This simplified description is a good beginning; however, “mixed” layers are generally not well-mixed. It is more precise to speak of the upper ocean as a zone where there may be periods of mixing and heating driven by changes in winds and cloud cover. Upper ocean models predict this evolution and often lead to much more complicated sound speed structures. This, in turn, has lead to a wide variety of ways of characterizing the features of the surface duct. This talk will touch on the interesting acoustics of surface ducts and how variations in different (oceanographic) upper ocean models effect the sound propagation.
Change in pitch and voice quality of L2 speakers of English as a function of similarity between their L1 and English
Authors: Koo Hahn
Published: November 2021

Bilingual speakers sometimes change their pitch and voice quality when they switch from one language to the other. For example, when speaking in L2 rather than L1, German learners of French pronounce vowels with less adduction of the vocal folds (Pützer et al., 2016), and Korean learners of English with a lower pitch (Cheng, 2020). Here, I present a corpus study which suggests that the extent to which L2 learners of English change their pitch and voice quality may depend on how similar their L1 is to English. I extracted 68 211 vowels—51 857 in L1 and 16 354 in L2—from 1617 speakers with 21 different L1 backgrounds (including English) in the CSLU: 22 Languages Corpus and measured F0, harmonics-to-noise ratio (HNR), and H1i–H2 for each vowel. I then computed two cluster distances for each L1 and for each measure: (1) vowels from the native English speakers versus L1 vowels from the learners and (2) L1 vowels versus L2 vowels from the learners. I found strong correlations between (1) and (2): r = 0.416 for F0 (p = 0.068), r = 0.531 for HNR (p = 0.016), and r = 0.374 for H1–H2 (p = 0.105).
Limits of Cantonese advantage on English stress discrimination: Rising pitch accent pattern and vowel reduction
Authors: Choi William
Published: November 2021

Can non-natives outperform natives on speech discrimination? Surprisingly, Cantonese listeners discriminated English stress more accurately than English listeners did. To ascertain its generalizability, I further asked whether this Cantonese advantage on English stress discrimination was equally potent across pitch accent and vowel reduction contexts. Sixty Cantonese and English listeners completed four blocks of English stress discrimination task with varying pitch accent and vowel reduction contexts. In the absence of rising pitch accent pattern and vowel reduction, the Cantonese listeners outperformed the English listeners on discriminating English stress. However, the Cantonese advantage disappeared when either rising pitch accent pattern or vowel reduction was present. When both rising pitch accent pattern and vowel reduction were present, the Cantonese listeners even performed poorer than the English listeners did. The findings underscore two constraints of the Cantonese advantage on English stress discrimination—rising pitch accent pattern and vowel reduction.
Recent ecological insights into the endangered Cook Inlet beluga via acoustic monitoring
Authors: Castellote Manuel , Polasek Lori , Olnes Justin , Garner Christopher , Taras Brian , Brewer Arial , Jenniges Justin , Gage Tom
Published: November 2021

The endangered Cook Inlet beluga population is non-migratory and located in south-central Alaska. Estimated at <300 individuals, it is declining more rapidly than previously thought. The Recovery Plan highlights a paucity of information on basic ecology impeding proper management decisions. The Alaska Department of Fish and Game and the National Marine Fisheries Service are collaborating on a passive acoustics monitoring program to address crucial information gaps. Year-round seasonal distribution and feeding occurrence is described for key areas within the critical habitat. Acoustic detections are greater in the upper inlet during summer, peaking in known concentration areas. Foraging peaks coincide with the presence of various anadromous fish runs from spring to fall. Low levels of feeding activity in winter suggest a lack of feeding aggregations in these areas. Thirteen sources of anthropogenic noise occur within the critical habitat, many exceeding behavioral harassment levels. Using a case-controlled approach in which periods with and without anthropogenic noise were compared, a significant negative correlation between noise levels and vocalization detections was found, However, masking by flow noise due to the strong currents in Cook Inlet might be affecting these results more than a true behavioral response. Further research remains ongoing to confirm/reject this hypothesis.
Acoustical characteristics of avian choruses in a western migratory bird refuge
Authors: Moats Levi T. , Cook Mylan R. , Teusch Claire L. , Hall Lucas K. , Gee Kent L. , Transtrum Mark K.
Published: November 2021

Migratory bird refuge soundscapes are seasonally dynamic due to changes in wildlife populations. Some of the most prominent acoustical events in a bird refuge are the morning and evening avian choruses, particularly during spring and early summer when breeding activity of birds is high. For this study, near-continuous spectral data were collected at the U.S. Federal Fish and Wildlife Services Bear River Migratory Bird Refuge. Although data fidelity can be compromised by wind and rain, changes in the avian chorus characteristics over time are observed. Likely correlations with avian migration and refuge land management are discussed.
Envelope modulation as a communicative cue mediating male–male interactions in bullfrogs
Authors: Simmons Andrea M. , Kloepper Laura
Published: November 2021

Chorusing male bullfrogs (Rana catesbeiana) modify the envelope waveforms of the individual notes in their advertisement calls in a stereotyped pattern. Natural advertisement calls begin with an unmodulated first note, with subsequent notes typically exhibiting increasing numbers of modulations. We asked whether these envelope modulations serve a male-male communicative function. In a playback design, we presented to actively chorusing males a series of notes with varying numbers of envelope modulations. We quantified the numbers of vocal responses as well as the total acoustic energy in calls of all males in the chorus. Over 12 experiments at two chorus sites, neither numbers of responses nor total energy differed significantly between stimuli. These two measures were highly correlated, indicating that the energy measure captured chorus dynamics. Modifications of envelope waveform do not appear to convey information to other males, and instead may be a byproduct of vocal production mechanics.