bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscopic Study on Heat Transfer and Thermophysical Properties of Composite Material
Authors: Nakabeppu Osamu , Igeta Masanobu , Hijikata Kunio
Published: March 2022

Microscale thermal measurement by the atomic force microscope (AFM) with a thermocouple probe has been investigated. Temperature distribution measurement of a small heater and thermal visualization of a composite material, carbon fiber reinforced plastic (CFRP), were conducted with controlling an ambient air pressure. In the temperature measurement, it has been shown a temperature image is affected by heat conduction through the ambient air in a spatial resolution and contrast. The performance is evaluated at 30 μm spatial resolution in a high contrast image under the atmospheric pressure condition, while less than 1 μm resolution in a noisy image under the low pressure condition. In the microscale thermal characteristics measurement, carbon fiber and epoxy resin in the CFRP are thermally distinguished by detecting contact point temperature, implying thermal visualization is possible. The heat conduc-tion simulation shows the thermal image displays overall thermal conductance of the sample from the back side to the contact point which is decided by contact scale, thermo-physical properties and material structure.
Exact Solution of Heat Conduction in Composite Materials and Application to Inverse Problems
Authors: Aviles-Ramos C. , Haji-Sheikh A. , Beck J. V.
Published: March 2022

Calculation of temperature in high temperature materials is of current interest to engineers. Aerospace industry encounters cooling problems in aircraft skins during the flight of high-speed air vehicles and in high-Mach-number re-entry of spacecraft. Generally numerical techniques are used to deal with conduction in composite materials. This study uses the exact series solution to predict temperature distribution in a two-layer body: one orthotropic and one isotropic. Often the exact series solution contains an inherent singularity at the surface that makes the computation of heat flux difficult. This singularity is removed, introducing a differentiable auxiliary function that satisfies the nonhomogeneous boundary conditions. An inverse heat conduction technique is used to predict surface temperature and/or heat flux.
Experimental Investigation of Heat Transfer and Pressure Drop Through Deep Microchannels in a (110) Silicon Substrate
Authors: Harms Todd M. , Kazmierczak Michael , Gerner Frank M. , Hölke A. , Henderson H. T. , Pilchowski J. , Baker Karl
Published: March 2022

Experimental results have been obtained for single-phase forced convection in deep rectangular microchannels. The microchannels were fabricated in a 2 mm thick silicon substrate by means of chemical etching. The tested configuration has 251 μm wide channels and 119 μm thick channel walls. The channel depth is 1030 μm and the channels cover a total projected area of 2.5 cm by 2.5 cm. A thin-film heater is deposited on the back side of the silicon substrate, corresponding to the entire projected channel area. The silicon substrate measures 2.9 cm by 2.9 cm, with only a 2 mm wide edge surrounding the channel area. All tests were performed with deionized water as the working fluid, where the liquid flow rate ranged from 5.47 cc/s to 118 cc/s. A critical Reynolds number of 1500 was found for this configuration, contrary to that of larger channels. The theoretical analysis as well as previous data found in the literature agree reasonable well with the experimental findings. This channel configuration has been shown to reduce temperature non-uniformity in the substrate compared to previous studies by utilizing relatively high flow rates. In addition, the theoretical analysis shows that increasing the channel depth can significantly improve the flow and heat transfer performance.
Turbulent Heat Transfer in a Forced and Unforced Two Dimensional Air Jet Impinging on an Isoflux Surface
Authors: Singer Edmund A. , Ortega Alfonso
Published: March 2022

Mean heat transfer and flow characteristics of a two-dimensional air jet impinging on a uniform heat flux surface were investigated. Measurements were made in a steady unforced jet, and in a jet with externally introduced forcing. The jet issued from a 24:1 aspect ratio rectangular nozzle. The heat transfer characteristics are parameterized by jet Reynolds number based on the hydraulic diameter and on the nozzle-to-plate spacing. Flow conditions (mean, turbulent fluctuations and power spectra) exiting the jet were measured and used to interpret their influences on the stagnation point heat transfer. A comparison of an unforced impinging jet to a forced impinging jet showed enhancements in the heat transfer rate of up to 57% with forcing.
The Effects of Inlet Turbulence on the Development of Fluid Flow and Heat Transfer in a Helically Coiled Pipe
Authors: Lin C. X. , Ebadian M. A.
Published: March 2022

In this paper, the effects of inlet turbulence on the development of turbulent flow and heat transfer in the entrance region of a helically coiled pipe are investigated by means of a fully elliptic numerical study. The k-ε standard two-equation turbulence model is used to simulate the three-dimensional turbulent flow and heat transfer. The governing equations are solved by a Control-Volume Finite Element Method with an unstructured nonuniform grid system. Numerical results presented in this paper cover a Prandtl number range of 0.02–100, and an inlet turbulence intensity range of 2–40 percent. The development of velocity field, temperature field, bulk turbulent kinetic energy, average friction factor, and average Nusselt number are discussed. It is found that bulk turbulent kinetic energy far from the entrance is not affected by the inlet turbulence level. Significant effects of the inlet turbulence level on the development of the friction factor and Nusselt number occur within a short axial distance from the entrance only.
Development of a High Flux Conduction Calibration Apparatus
Authors: Grosshandler William L. , Blackburn David
Published: March 2022

A new conduction calibration apparatus has been designed to deliver heat fluxes up to a maximum of 100 kW/m2 with an established goal of ± 5 % precision. This system will provide a close to purely diffusive (as opposed to radiative) heat flux boundary condition and, when compared to the gauge’s response in the National Institute of Standards and Technology (NIST) radiative calibration facility, act as a check on the sensitivity of a heat flux gauge to the mode of heat transfer. A platinum-plated copper block heated electrically with 2 kW power is designed to produce uniform temperatures up to 750 K across its face. A cold plate will be maintained around 290 K through pool boiling using a liquid refrigerant and a remote condenser. A 1 mm wide helium filled gap between the hot plate and the sensing surface of a cooled heat flux gauge will provide the high conductive fluxes desired (while limiting radiation to a few per cent and avoiding the uncertainties associated with contact resistance). Detailed numerical modeling of the device is being used to identify limitations and evaluate alternatives in the design, and to analyze the level of uncertainty associated with the facility. A description of the apparatus and the results of preliminary modeling are reported.
Laminar Forced Convection Near an Asymmetric Contraction in a Channel
Authors: McAuliffe Wayne E. , Wirtz R. A.
Published: March 2022

The flow and heat transfer characteristics in the region of an asymmetric contraction in a two-dimensional channel are studied numerically. The contraction is in the form of a step on one of the channel walls. Channel wall-to-wall spacing ranges from 2 step heights to 10 step heights, with Reynolds numbers, based on channel hydraulic diameter, ranging from 500 to 2500.

Separation and recirculation regions occur upstream from the contraction; the flow generally separates on the order of one step height upstream from the step and re-attaches approximately one-half the distance up the step face. In some cases there is a recirculation region on the top of the step, beginning just downstream from the leading edge of the step, and typically a few step heights in extent. Heat transfer is reduced in the recirculation regions, relative to that of a parallel-wall flow. In addition, there is heat transfer augmentation on the wall opposite the step, not only because of the contraction itself, but also enhanced by the flow around the recirculation regions. Correlations are reported for friction factor and for heat transfer augmentation and reduction, and results are reported for location of separation and reattachment points and for heat transfer across the entire region.
Thermal Transport Phenomena in Turbulent Gas Flows Through a Tube With High Constant Wall Temperature
Authors: Torii Shuichi , Yang Wen-Jei
Published: March 2022

A numerical study is performed to investigate thermal transport phenomena in turbulent gas flow through a tube with high uniform wall temperature. A k-ε turbulence model is employed to determine the turbulent viscosity and the turbulent kinetic energy. The turbulent heat flux is expressed by Boussinesq approximation in which the eddy diffusivity of heat is determined by a t2¯-εt heat-transfer model. The governing boundary-layer equations are discretized by means of a control volume finite-difference technique and numerically solved using a marching procedure. It is disclosed from the study that: (i) Like in a pipe with high uniform wall heat flux, laminarization takes place in a turbulent gas flow through a pipe with high uniform wall temperature, (ii) Once laminarization occurs, both velocity and temperature gradients at the wall diminish along the flow, resulting in a substantial reduction in both the turbulent kinetic energy and temperature variance across the whole tube cross section, and (iii) these attenuations cause a deterioration in heat transfer performance.
Acoustic-Wave Liquid Mixer
Authors: Zhu Xu , Kim Eun Sok
Published: March 2022

This paper presents a novel approach for microfluid mixing by loosely-focused acoustic waves (generated by piezoelectric Zinc Oxide thin film). Initial results show that our acoustic-wave liquid mixer (AWLM) produces a convection flow in liquid very efficiently, when it is driven by a sinusoidal wave with frequencies corresponding to the thickness-mode resonances (e.g. 240 and 480 MHz) of the piezoelectric film. The AWLM operates without any significant temperature increase in liquid, and will be very attractive for mixing temperature-sensitive fluids.
Microactuators Based on Electrothermal Expansion of Clamped-Clamped Beams
Authors: Chiao Mu , Lin Liwei
Published: March 2022

Thermally driven microactuators based on clamped-clamped beams have been successfully demonstrated. A theoretical model which includes both electrothermal and thermo-elastic responses of the micro beams has been established. These micro beams are made of heavily phosphorus doped polysilicon by a surface micromachining process. Theoretically, a 2 μm wide, 2.2 μm thick and 100 μm long beam can have a actuated displacement at the center point of about 2.7 μm under a 6 mA input current. The analytical results are consistent with experimental measurements which use computer image processing schemes to measure the lateral displacements.
Strength and Fracture of Micromachined Silicon Structures
Authors: Suwito Wan , Dunn Martin L. , Cunningham Shawn J.
Published: March 2022

We present our recent efforts to understand and characterize the mechanical behavior of micromachined single crystal silicon structures. This includes efforts directed toward the design and fabrication of free-standing thin film test structures and toward micromechanical tensile testing. We observed that in many cases, fracture of the test structures initiates at sharp corners that arise from the anisotropic wet etching process. Existing approaches do not appear to be suitable to correlate fracture initiation from these sharp corners. To remedy this, we propose a new approach that is able to describe the apparent strength scaling with specimen size that is observed experimentally. This scaling has obvious ramifications with regard to the design of reliable structures for microelectromechanical systems, without exhaustive verification testing.
Tr-1A Rocket Experiment on Nucleate Pool Boiling Heat Transfer Under Microgravity
Authors: Ohta H. , Kawaji M. , Azuma H. , Kawasaki K. , Tamaoki H. , Ohta K. , Takada T. , Okada S. , Yoda S. , Nakamura T.
Published: March 2022

To clarify the reason of inconsistent trends in the existing heat transfer data in microgravity nucleate boiling, the method to acquire the local heat transfer data and to observe in detail the bubble behavior from underneath was developed and introduced in the experiment by the use of the NASDA TR-1A ballistic rocket. The pool boiling experiment was conducted using ethanol as test liquid at an almost constant temperature of 25 to 30°C. The system pressure was varied from 0.01 to 0.48MPa with corresponding liquid subcooling from 3 to 95K. The steady state heat transfer is realized in microgravity at the conditions of moderate and high subcooling where the bubble size is determined so that the rate of evaporation of microlayer balances that of condensation at the bubble surface. On the other hand, the transition to burnout is unavoidable even at low heat flux when the liquid of low subcooling is concerned. The nucleate boiling heat transfer is dominated by the isolated or primary bubbles just generated on the heat transfer surface even in the high heat flux or the low liquid subcooling region where these bubbles lift the large coalesced one covering the entire heating surface. Two opposite trends of the heat transfer enhancement and deterioration are possible depending on the behavior of dry patches extending in the microlayer underneath the bubbles contacting directly with the surface.
Double Diffusive Convection in a Stratified Fluid Layer Induced by Thermal and Solutal Capillary Motion
Authors: Chan C. L. , Chen C. F.
Published: March 2022

Salt-finger convection in a double-diffusive system is a motion caused by the release of gravitational potential due to differential diffusion rates. The normal expectation is that, when gravitational field is reduced, salt-finger convection together with other convective motions driven by buoyancy forces will be rapidly suppressed. However, because the destabilizing effect of the concentration gradient is amplified by the Lewis number, with values varying from 102 for aqueous salt solutions to 104 for liquid metals, salt-finger convection may be generated at much reduced gravity levels. In the microgravity environment, the surface tension gradient assumes a dominant role in causing fluid motion. In this paper, we report experimental and numerical results showing the generation of salt-finger convection due to capillary motion on the surface of a stratified fluid layer.
A Second Law in Engineering Education
Authors: El-Sayed Yehia M. , Gaggioli Richard , Ringhausen David P. , Smith Joseph L. , Gyftopoulos Elias , Sama Dominick , Fiszdon Jerzy K.
Published: March 2022

Several panel sessions sponsored by the System Analysis Technical Committee of the ASME Advanced Energy Systems Division were held as a part of 1996 IMECE’s Symposium on Thermodynamics and the Design, Analysis, and Improvement of Energy Systems in Atlanta, GA. Panel Session on the Second Law in Engineering Education was one of them. Panelists included representatives of both, academia and industry. Discussion included the need to educate undergraduate engineers in the Second Law of Thermodynamics and to what depth this education should be. Educational approaches used by participants were also the subject of discussion.
An Investigation on Bubble Growth in Superheated Liquid During Rapid Decompression
Authors: Liu Chao , Zeng Danling
Published: March 2022

A mathematical model of bubble growth in superheated liquid during rapid decompression was built up on the basis of non-equilibrium thermodynamics. According to the principles of thermodynamics it is asserted that the bubble growth process can be described by a polytropic process rather than assuming that it goes along the saturation curve as usually suggested in existing article. The value of the polytropic exponent n is restrict to a ranges of 1 ≤ n ≤ nσ < k to guarantee the existence of a positive driving force to drive the phase transition process. Numerical simulation of the bubble growth process was performed for water by using the model proposed. The results obtained were compared with experimental data provided by other authors. Good agreement was achieved.
Conversion of Ocean Thermal Energy With the “Salt Cycle”
Authors: Saikia Siddarth
Published: March 2022

A temperature gradient exists between the top and the depths of oceans, the “Salt Cycle” is targeted at converting this thermal energy. The phases of certain solutions (liquid-liquid or solid-liquid) separate out at lower temperatures enabling the separation of the solute. By placing the solute behind a semipermeable membrane, at a higher temperature, an osmotic pressure can developed. The pressure released into a turbine can generate power or may be put to other uses like desalination.
The Constructal Law of Structure Formation in Natural Systems With Internal Flows
Authors: Bejan Adrian
Published: March 2022

This paper outlines a series of recent developments that provide a theoretical basis for the formation of shape and structure in nonequilibrium (flow) systems subjected to overall constraints. It is shown that geometrical form can be deduced from a single principle: the geometric minimization of resistance to flow. This is illustrated in two ways: by minimizing the flow resistance between a finite volume and one point, and by minimizing the time of travel between a finite area and one point.

The discovery is that any volume element can have its shape optimized such that its flow resistance is minimal. This principle applies at any volume scale. The given volume is covered in successive steps of optimization and construction. Optimally shaped elements are grouped into a “construct,” and then the shape of the construct is optimized. The more visible portion of the optimized volume-to-point flow path that emerges is a tree network that is completely deterministic. This solution has a definite time direction: from small to large, hence the name “constructal.” Small size and slow and shapeless flow (diffusion) come first, and larger sizes and organized flows (streams) come later.
Evaluation of Zeotropic Refrigerant Mixtures R32/R134A in Flow Condensation
Authors: Shao D. W. , Granryd E.
Published: March 2022

Experiments on flow condensation have been conducted with pure R32, R134a and R32/R134a mixtures. The results have been represented in form of local and mean heat transfer coefficient, as well as pressure drop. The heat transfer data is compared with the prediction from correlations in literature. An analysis is also carried out on potential causes of heat transfer degradation associated with NARMs.
Discharge Gas Cooling in Vacuum Pumps
Authors: Prasad B. G. Shiva
Published: March 2022

Heating of the gas is an undesirable effect of the compression process, particularly in vacuum pumps and high pressure ratio reciprocating compressors. ‘Discharge gas cooling’ is analogous to the commonly known phenomenon of ‘suction gas heating’, but unlike the latter, discharge gas cooling is beneficial to the user of a vacuum pump. This paper describes a technique for modeling the complex heat transfer process by breaking it up in to different stages and calculating the heat transferred during each stage for estimating the discharge temperature. The method was validated by comparing the results with experimental data for a vacuum pump tested over a range of operating conditions.
Pressure Pulsation of Scroll Compressor
Authors: Itoh Takahide , Fujitani Makoto
Published: March 2022

Pressure pulsation in the scroll compressor was analyzed with three dimensional FLIC (flow in cell) method which was a kind of finite volume method.

In advance of analyses, the grid generation method for numerical analysis was established in the scroll compression chamber.

According to compression progress, grids in compression chambers are transformed and each conservation quantity which transport through the grid boundary was adjusted by moving boundary velocity.

The overset grid was used between compression chamber and discharge port.

In the overset grids, grids nodes of the discharge port are not located in same points of the compression chamber grid nodes. In this case the conservation quantity on the boundary is interpolated between every adjacent grids. However, we simplified interpolation with treating the discharge port as one grid.

Using this program, it is possible to predict the suction pressure pulsation, the compression pressure pulsation and the discharge pressure pulsation in the scroll.

Finally the supercharging construction using the suction pressure pulsation was developed and it is confirmed the supercharging effect of the suction path shape and the suction path length experimentally.
Finite Difference Time Domain Simulation of Scattering From Submerged Elastic Bodies
Authors: Nagem Raymond J. , Lei Xun , Felsen Leopold B.
Published: March 2022

A two-dimensional finite difference time domain (FDTD) algorithm is implemented to simulate wave propagation and scattering in a heterogeneous fluid-elastic environment. The FDTD algorithm is fourth-order accurate in space and second-order accurate in time. The perfectly matched layer (PML) absorbing boundary condition is adapted to eliminate artificial reflections caused by the boundaries of the finite computational domain. Computational accuracy is verified by considering radiation from a periodic array of pulsed line sources and from a fluid line source near a submerged elastic layer. The finite difference results are in excellent agreement with the numerically evaluated spectral integrals which can be derived for these problems. The finite difference algorithm is then applied to scattering from a rough fluid-solid interface, and to scattering from an elastic cylinder above or buried beneath a rough fluid-solid interface. Scattered signals are processed with the Gaussian windowed transform, which provides an initial image representation for signature identification and classification algorithms.
The Effect of Toughened Composites on the Static Buckling Load and Buckled Position of Composite Laminated Plates
Authors: Jia Hongyu , Rogers Craig A.
Published: March 2022

A nonlinear analysis of the buckling and post-buckling responses of a simply supported laminated composite plate under an axial in-plane compressive load is presented. The model for symmetric cross-ply laminated composite plates made from various composite materials, such as, Graphite/Epoxy, Graphite/PEKK, Graphite/PEEK, and Kevlar/PEKK is given here. The governing equations of post-buckling composite plates with large strains are obtained by using the minimum total potential energy principle. The post-buckling behaviors of Graphite/Epoxy composite plate and toughened composite plates are studied by using this model. The critical buckling load and buckled position are determined. The stress and strain fields of the buckled composite plates are also determined. Buckling analysis is combined with failure analysis by applying Tsai-Hill theory. The effect of the toughened composites (matrix, or fibers or both) on the critical buckling load, post buckling behavior of the laminated composite plates are evaluated.
Vibroacoustic Testing of Linings of Clutches
Authors: Karagulle Hira
Published: March 2022

The density of a clutch lining is an important parameter for its quality. In this work, a nondestructive vibroacoustic test is studied for evaluating the quality of linings. First, the mechanics of the test is studied. The theoretical model shows that the high frequency components of the nondestructive impact force transmitted to the structure decrease if the contact stiffness decreases. The acoustic signals (0–20 kHz) and acousto-ulstrasonic signals (0–40 kHz) are generated by tapping on the linings. 7 linings in good quality with an average density of 1.96 g/cm and 7 linings in bad quality with an average density of 1.65 g/cm3 are considered. The linings are the product of a commercial company. A microphone is used to detect acoustic signals and an acoustic-emission sensor is used to detect the acousto-ultrasonic signals. The signals are captured by a data acquisition card and are analyzed in a personal computer. The spectra of the signals are smoothed by the cepstral analysis. The amplitudes of the smoothed spectra are compared in various frequency bands. The difference in the amplitudes for good and bad quality linings are compared. It is observed that the difference in high frequency components can be used as an indicator of the quality of friction linings.
Fatigue Damage of Glass/Vinyl Ester Thick Composites
Authors: Haque A. , Johnson J. , Vaidya U. K. , Jeelani S.
Published: March 2022

The focus of this study is to investigate the compression-compression fatigue damage of S2-glass/vinyl ester woven composites manufactured through Vacuum Assisted Resin Transfer Molding (VARTM). The compressive behavior and the relevant failure modes of composites are investigated prior to applying the cyclic load. The panels of thicknesses (0.15 in./3.81mm – 0.45 in./11.43 mm) are considered to quantify the process related defect such as void contents and fiber waviness in the thick composite laminates. Void content of each panel is determined through a bum-off test method using a Thermal Gravitational Analyzer (TGA). An optical microscope attached with a grid pattern transparent film is used to measure the waviness parameters of the laminate. The ultrasonic C-scan, A-scan and microscopic examinations are used to identify the manufacturing flaws related to VARTM. The effects of such defects on static compression and compression-compression cyclic behavior of thick composites are investigated. The failure strength, failure strain, modulus and number of cycles to failure at different stress levels for various laminate thicknesses are determined. Weibull plots are generated using both static compression strength and fatigue life cycles. Although the range of the thickness of the laminate was in the ratio of one to three, the variation in compressive strength data was rather nominal. The fatigue performance is observed to improve with the increase in thickness. In-situ monitoring of progressive damage under compressive and cyclic loading is conducted using acoustic emission (AE) method. AE parameters in the form of amplitude, energy and time plots are generated. The compressive and fatigue failure modes are identified by optical and scanning electron microscopic examinations. These failure modes are correlated with acoustic emission Non Destructive Evaluation (NDE) parameters.
Simulation of the Noise Radiated From an Operating Diesel Engine
Authors: Vlahopoulos Nickolas , Kalish Yury , Stark Richard D.
Published: March 2022

Numerical methods can be used to compute the vibration of powertrain systems or components and the corresponding radiated noise. Specifically, the finite element method can be utilized in computing the structural vibration[l-3]. The structural response constitutes the boundary conditions for the acoustic analysis. The boundary element method is utilized in computing the radiated noise[4–6]. In order to achieve reliable noise predictions it is important to have accurate information for the structural vibration since it is the source of the noise. In this work a methodology for applying the loads on the structure is presented. It allows to exert as excitation a combination of measured accelerations, and forces or pressures. It is utilized in simulating the noise radiated from a running engine and determining the effects of design changes. Numerical results for the radiated noise are compared to test data for a baseline design. The effect of two structural design modifications on the radiated noise is computed, and conclusions are deducted.
Flow Noise Source: Resonator Coupling
Authors: Pollack Martin L.
Published: March 2022

This paper investigates the coupling mechanism between flow noise sources and acoustic resonators. Analytical solutions are developed for the classical cases of monopole and dipole types of flow noise sources. The effectiveness of the coupling between the acoustic resonator and the noise source is shown to be dependent on the type of noise source as well as its location on the acoustic pressure mode shape. For a monopole source, the maximum coupling occurs when the noise source is most intense near an acoustic pressure antinode (i.e., location of maximum acoustic pressure). A numerical study with the impedance method demonstrates this effect. A dipole source couples most effectively when located near an acoustic pressure node.
Designing Applications for an OSACA Control
Authors: Sperling Wolfgang , Lutz Peter
Published: March 2022

Within the ESPRIT III project OSACA (Open System Architecture for Controls within Automation systems) of the European Commission the necessary specifications for an open control system were worked out and first prototypes of the system platform were realized. The system platform is the basis of the OSACA architecture and acts as the framework for the integration of application-oriented functionality in a control system.

Several initiatives — under them the German project HÜMNOS — are developing application modules for the OSACA architecture. This paper describes the results that have come out of the OSACA initiative so far, and explains the general structure and design of control applications for the provided framework. Special emphasis is put on the reference architecture which guarantees the interoperability between the single control-specific, vendor-neutral application modules. As illustration, the interaction of an HMI application with OSACA compliant controllers of different vendors is presented.
Intelligent Process Monitoring for Rough Milling Operations Based on Digital Drive Currents and Machine Integrated Sensors
Authors: Kaever Michael , Weck Manfred
Published: March 2022

In Europe a consortium has been formed to develop a Sensor Fused Intelligent Monitoring System for Machining (SIMON). Starting from a generic module structure for process monitoring systems, the system architecture of a fully control integrated monitoring system for rough milling operations is presented based on digital drive signals. Machine integrated sensors are used for calibration and for wear monitoring. The potential of such a system is shown by previous work at WZL. Experimental results demonstrate successful tool overload and tool breakage monitoring for milling and drilling, based on drive current signals. Comprised only of software modules, directly linked into an industrial open system controller, the base system does not need any sensor or signal processing hardware to monitor 06mm drilling or 08mm end milling tools machining steel workpieces. Signal correction has been designed for monitoring during acceleration. Machine integrated sensors are presented to extend the range of reliable monitoring.
Solder Joint Formation Simulation and Component Tombstoning Prediction During Reflow
Authors: Wu Xiaohua , Dou Xinyu , Yeh Chao-pin , Waytt Karl
Published: March 2022

The failure of electrical devices associated with solder joints has become one of the most critical reliability issues for surface-mounted devices. Solder joint reliability performance has been found to be highly dependent on the solder joint configuration, which, in turn, is governed by bond pad size, alloy material, and leadframe structure, as well as solder reflow characteristics. To investigate Tombstone effect causing solder joint failure during leadless component reflow process, this work has focused on 1) developing numerical model for the simulations of the solder joint formation during the reflow process; 2) determining possibility that a tombstone effect for the leadless component may occur by analyzing the force and torque in the problem. Using this methodology, the Tombstone effect associated with different pad geometry configurations has been analyzed though the application of the software tool Surface Evolver. Simulations show that the tombstoning is very sensitive to pad / component geometry design, solder surface tension, paste volume, wetting area and wetting angle. This model simulation can be used to determine optimal solder paste volume, pad geometry configurations and solder material for avoiding Tombstone effect.
Applications of Digital Correlation Method to Microscopic Strain Measurement and Materials’ Property Characterization
Authors: Lu H.
Published: March 2022

The method of digital speckle correlation is introduced, so is the hardware system to implement the method. The advantages and the features of the technique are discussed and application examples are given. Owing to the high spatial resolution that this technique can achieve, the method is especially useful to measure small areas of an object, or a small component in an assembly, whether the surfaces under probing are planar or not. The applications have proved that the technique is a promising tool for the reliability study of microelectronic packages.
An Experimental Investigation on Application of Basic Orthogonal Cutting Model to Ultra-Precision Diamond Cutting
Authors: Okuda Koichi , Hasegawa Motoyoshi , Moriwaki Toshimichi
Published: March 2022

The orthogonal cutting tests were carried out on an ultra precision fly-cutting machine at various depths of cut from 3 μm down to 0.0015 μm (1.5 nm). The cutting force, thickness of chip and contact length between the chip and the rake face of tool were measured in the experiments. The effect of the depth of cut on the cutting force, the shear angle, the tool-chip contact length and the cutting heat were presented and compared with the results of conventional orthogonal cutting process. The compatibility and the limitation of application of basic orthogonal cutting model to ultra-precision cutting was investigated. The experimental data obtained by ultra-precision diamond cutting have a good agreement with the shear angle equations based on basic orthogonal cutting model under the conditions of depth of cut more than 0.2 μm but not at depths of cut smaller than 0.2 μm due to the rounded edge of tool.
Preliminary Results of Laser-Assisted Cleaning of Alumina Coated Carbide Tool Inserts
Authors: Malshe Ajay P. , Khor Kok E. , Bhat Deepak G.
Published: March 2022

This paper describes the results of a preliminary investigation of a novel non-contact surface cleaning method for the reclamation of coated cemented carbide cutting tools. Conventional cleaning processes used for cleaning of cutting tools rely either on aqueous methods which are often not very effective, mechanical methods such as grit blasting which can damage the tool cutting edges, or high-temperature chemical stripping methods which significantly reduce the strength and fracture toughness of the tools. In the present work, cobalt-bonded cemented carbide cutting tool inserts coated with titanium carbonitride (TiCN) and alumina (Al2O3) by CVD process were treated by an excimer laser-based technique to effectively remove partially delaminated or poorly bonded coating layers. The goal was to investigate the feasibility of applying a non-contact technique which is environmentally friendly, and is capable of large-scale application and automation. It is postulated that the process works by explosive and thermal shock which essentially delaminate the coating.
Composite Modeling of Human Cranial Bone
Authors: Hu Hao , Nayfeh Adnan H. , Rosenberg William S.
Published: March 2022

The purpose of this paper was to address an equivalence between a single layer and three layered cranial bone models for intracranial content impact injuries by using composite mechanics approach. A homogenized material model was utilized to model the three layered system of cranial bones as a single layered system. A set of equivalent homogenized material properties can be formulated systematically with confidence. Numerical verifications were carried out by simulating two ball models and a 50th percentile human head model by using finite element approach, which shows that it maximizes modeling and computation economy without sacrificing solution accuracy of variables for evaluating intracranial content injuries. The discrete bone materials were assumed as linear, elastic, and isotropic. So, the resultant equivalent material was anisotropic.
The Recommended Geometry for Laminar Microchannel Heat Sinks
Authors: Lienau Jeffrey J.
Published: March 2022

Rectangular laminar microchannel heat sinks have been used for cooling banks of integrated circuits, semiconductor laser diodes, radar components and optical devices all of which may generate high heat flux. The effect of varying the fin width to channel width ratio and the channel aspect ratio was investigated for silicon heat sinks and the design which provided the minimum base temperature for a given heat transfer rate and given pumping power was recommended. The recommended design had fin width to channel width ratios of 1.3 and 2.4 and channel aspect ratios of 21.2 and 32.8 for water and Fluorinert (FC-5312) coolants respectively. The constant properties, fully developed assumptions were evaluated and were shown to be acceptable for the recommended geometry.
Contact Area and Thermal Contact Resistance in an Ideal Bolted Joint: Part 1 — Study of Contact Area
Authors: Park Chang J. , Kaminski Deborah A.
Published: March 2022

The contact area at the interface of a bolted joint was investigated analytically, experimentally and numerically. Consideration was restricted to an ideal two-plate model for which the interface was perfectly flat. The two plates made circular contact under uniform axisymmetric normal loading. These investigations included the effect of important system parameters such as plate thickness, material properties and loading radius. In the analytical study, a two-plate model with an infinite radius, which had no center (bolt) hole, was mathematically analyzed. The normal stress distribution at the interface was used to predict the contact radius. Two alternative assumptions were considered: 1) continuous contact (no separation) at the interface, 2) discontinuous contact (separation beyond the contact region) at the interface. The continuous model was solved by a Hankel transform and the discontinuous model by a Hankel transform and singular integral formulation.

In the experimental study, a visualization technique using monochromatic light was carried out with a bolted joint which consisted of a transparent polycarbonate plate and a metal plate so that direct calibration of the contact radius was possible. All the test plates had mirror-like surface finishes.

In the numerical study, the finite element method was applied to two different two-plate models: one without a hole and the other with a hole.

The results showed that the discontinuous model produced much closer agreement with the two-plate model with a hole than the continuous model, which produced a large discrepancy. The results also show that the effect of the bolt hole appeared to be insignificant. The physical behavior of the contact radius of a bolted joint can be well explained from the mathematical equation of the discontinuous model. The contact radii obtained from Part 1 were implemented in the study of the thermal contact resistance described in the companion paper.
Characterization of Plastic Packages Using (100) Silicon Stress Test Chips
Authors: Zou Y. , Suhling J. C. , Jaeger R. C. , Lin S. T. , Nguyen L. , Gee S. A.
Published: March 2022

In this work, special (100) test chips containing optimized four element dual polarity rosettes have been applied within several plastic encapsulated electronic packaging configurations. The utilized test chips are capable of evaluating four stress components, and both the in-plane normal stress difference and the in-plane shear stress can be measured in a temperature compensated manner. In this paper, results are reported for test chips encapsulated in 44 pin PLCC packages. The pre and post packaging room temperature resistances of the sensors were recorded. Using the measured resistance changes and the appropriate theoretical equations, the stresses on the surface of the die were then calculated. Also, three-dimensional nonlinear finite element simulations of the plastic encapsulated packages were performed. The experimental results are in reasonable agreement with the finite element predictions, given the limitations of the constitutive models used in the numerical calculations.
Evaluation of Die Stress Using van der Pauw Sensors
Authors: Mian A. K. M. , Suhling J. C. , Jaeger R. C. , Wilamowski B. M.
Published: March 2022

Piezoresistive sensors fabricated on (100) and (111) silicon surfaces are capable of measuring from four to all six stress components on the surface of a die. Such resistor based sensors have been successfully designed and fabricated on these wafer planes, and are being used for measurement of die stresses in electronic packaging. However, the use of resistor sensors has several drawbacks including their large size, low sensitivity, and limited functional temperature range. Van der Pauw (VDP) structures have been identified as one potential sensor candidate for overcoming the limitations of large resistor sensors. In this paper, the feasibility of using van der Pauw structures as stress sensors has been demonstrated. The sensitivity of VDP structures fabricated on both (100) and (111) silicon surfaces to uniaxial stress has been measured using four-point-bending tests, and typical results are presented. The observed VDP stress sensitivities are much higher than those of their analogous resistor sensor counterparts. Preliminary finite difference based anisotropic conduction simulation results are in general agreement with the observed measurements.
Experimental and Numerical Study of Propeller Induced Tunnel Pressures
Authors: Kimball Richard , Choi Jin Keun , Kinnas Spyros A.
Published: March 2022

This paper first describes Phase III of the CAvitating PRopeller Experiment (CAPREX) performed at MIT’s variable pressure water tunnel. The three components of the screen generated nominal wake inflow were measured using an LDV system. The unsteady pressure field on the upper tunnel wall for the first three blade harmonics was also measured in a 5 × 5 grid above the propeller tip, for various propeller cavitation conditions from fully wetted to super-cavitating. Then, a recently developed numerical method which models the flow of a cavitating propeller inside of a tunnel is used for the calculation of the pressures on the tunnel walls. The effects of a time-varying blade cavity source and of the flexibility of the tunnel walls are included in the calculation. Lastly, the predicted pressures are compared directly to those measured in the experiment.
Relationship of Fitness Combine Results and National Hockey League Performance: A 25-Year Analysis
Authors: Cohen Jeremy N. , Thompson Kyle M.A. , Jamnik Veronica K. , Gledhill Norman , Burr Jamie F.
Published: March 2022

Purpose: Along with past performance, professional teams consider physical fitness and physiological potential in determining the value of prospective draft picks. The National Hockey League (NHL) Combine fitness results have been examined for their ability to predict draft order, but not bona fide hockey performance. Therefore, we sought to identify the relationships of combine fitness test results to short- and long-term NHL performance. Methods: During NHL Combine fitness testing (1994–2007), a standardized battery of tests was conducted. Player performance (1995–2020) was quantified using career cumulative points, time on ice, transitional period to playing in the NHL, and NHL career length. Forward and defensive positions were considered separately. Goalies were not considered. Stepwise linear regression analysis was used to identify fitness variables that predict NHL success. Results: Overall models ranged in their predictive ability from 2% to 16%. The transitional period was predicted by peak leg power and aerobic capacity (; forwards, R2 = .03, and defense, R2 = .06, both P < .01). Points and time on ice within seasons 1 to 3 were predicted by peak leg power and for forwards and defense (R2 = .02–.09, P < .01). Among players accumulating 10 NHL seasons, cumulative points were inversely related to upper-body push-strength-related variables in forwards (R2 = .11) and defense (R2 = .16; both P < .01). Conclusions: The NHL Combine fitness testing offers meaningful data that can inform the likelihood of future success. Peak leg power and predict league entry and early career success. Counterintuitively, upper-body strength is inversely related to long-term performance, which may offer insight into recruitment strategies, player development, or differential team roles.
Vasopressin-oxytocin–type signaling is ancient and has a conserved water homeostasis role in euryhaline marine planarians
Authors: Kobayashi Aoshi , Hamada Mayuko , Yoshida Masa-aki , Kobayashi Yasuhisa , Tsutsui Naoaki , Sekiguchi Toshio , Matsukawa Yuta , Maejima Sho , Gingell Joseph J. , Sekiguchi Shoko , Hamamoto Ayumu , Hay Debbie L. , Morris John F. , Sakamoto Tatsuya , Sakamoto Hirotaka
Published: March 2022

Vasopressin/oxytocin (VP/OT)–related peptides are essential for mammalian antidiuresis, sociosexual behavior, and reproduction. However, the evolutionary origin of this peptide system is still uncertain. Here, we identify orthologous genes to those for VP/OT in Platyhelminthes, intertidal planarians that have a simple bilaterian body structure but lack a coelom and body-fluid circulatory system. We report a comprehensive characterization of the neuropeptide derived from this VP/OT-type gene, identifying its functional receptor, and name it the “platytocin” system. Our experiments with these euryhaline planarians, living where environmental salinities fluctuate due to evaporation and rainfall, suggest that platytocin functions as an “antidiuretic hormone” and also organizes diverse actions including reproduction and chemosensory-associated behavior. We propose that bilaterians acquired physiological adaptations to amphibious lives by such regulation of the body fluids. This neuropeptide-secreting system clearly became indispensable for life even without the development of a vascular circulatory system or relevant synapses.
The toll of white privilege
Authors: Mervis Jeffrey
Published: March 2022

How the dominant culture in physics has discouraged diversity
Called to teach
Authors: Smart Ashley
Published: March 2022

Black physics Ph.D.s are more than twice as likely as other groups to teach in high schools and community colleges. For many, it’s a mission
Regulator halts assembly of fusion reactor
Authors: Clery Daniel
Published: March 2022

ITER must meet safety concerns before welding giant tokamak sections
Mammoth mangrove bacterium has complex cell
Authors: Pennisi Elizabeth
Published: March 2022

“Eye-opening” discovery challenges evolutionary thinking on microbes
U.N. panel warns of warming’s toll and an ‘adaptation gap’
Authors: Voosen Paul
Published: March 2022

Impact of climate change will be worst for the natural world and humanity’s most vulnerable