bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Numerical Study of Three-Dimensional Natural Convective Heat Transfer From a Plate With a “Wavy” Surface
Authors: Oosthuizen Patrick H. , Garrett Matt 
Published: November 2021

Abstract
Natural convective heat transfer from a wide isothermal plate which has a “wavy” surface, i.e., has a surface which periodically rises and falls, has been numerically studied. The surface waves run parallel to the direction of flow over the surface and have a relatively small amplitude. Two types of wavy surface have been considered here — saw-tooth and sinusoidal. Surfaces of the type considered are approximate models of situations that occur in certain window covering applications, for example, and are also sometimes used to try to enhance the heat transfer rate from the surface. The flow has been assumed to be laminar. Because the surface waves are parallel to the direction of flow, the flow over the surface will be three-dimensional. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces, this being treated by means of the Boussinesq type approximation. The governing equations have been written in dimensionless form, the height of the surface being used as the characteristic length scale and the temperature difference between the surface temperature and the temperature of the fluid far from the plate being used as the characteristic temperature. The dimensionless equations have been solved using a finite-element method. Although the flow is three-dimensional because the surface waves are all assumed to have the same shape, the flow over each surface thus being the same, and it was only necessary to solve for the flow over one of the surface waves. The solution has the following parameters: the Grashof number based on the height, the Prandtl number, the dimensionless amplitude of the surface waviness, the dimensionless pitch of the surface waviness, and the form of the surface waviness (saw-tooth or sinusoidal). Results have been obtained for a Prandtl number of 0.7 for Grashof numbers up to 106. The effects of Grashof number, dimensionless amplitude and dimensionless pitch on the mean heat transfer rate have been studied. It is convenient to introduce two mean heat transfer rates, one based on the total surface area and the other based on the projected frontal area of the surface. A comparison of the values of these quantities gives a measure of the effectiveness of the surface waviness in increasing the mean heat transfer rate. The results show that while surface waviness increases the heat transfer rate based on the frontal area, the modifications of the flow produced by the surface waves are such that the increase in heat transfer rate is less than the increase in surface area.
An Interferometric Study of Convective Heat Transfer From an Irradiated Complex Window Assembly
Authors: Collins M. , Harrison S. J. , Naylor D. , Oosthuizen P. H. 
Published: November 2021

Abstract
The present experimental study examines the influence of heated, horizontal, and rotateable louvers on the convective heat transfer from a heated or cooled vertical isothermal surface. The system represents an irradiated Venetian blind adjacent to the indoor surface of a window. Detailed temperature field and local surface flux data were obtained using a Mach-Zehnder Interferometer for two window temperatures (warm and cool compared to ambient) and irradiation levels, two louver to plate spacings, and three louver angles. The results have been used to validate a previous numerical study, in which a steady, laminar, two-dimensional, conjugate conduction / convection / radiation finite element model of this problem had been developed.
The effect of the heated louvers on the heat transfer rate from the plate surface has been demonstrated and the results of the previous numerical study have been validated. With few exceptions, steady but periodic heat flux along the plate has been confirmed. More importantly, increased independence of the results from the louver angle as louver to plate distance increased was observed. Blind temperatures measured during the experiment also correlated well with those predicted numerically.
Tracer Dispersion in Stochastically Reconstructed Porous Media
Authors: Galani A. N. , Kainourgiakis M. E. , Kikkinides E. S. , Stubos A. K. , Chatzichristos C. , Muller J. , Papaioannou A. 
Published: November 2021

Abstract
Aim of the present study is the simulation of tracer transport in porous media. Three-dimensional images of porous materials are generated using stochastic reconstruction techniques. Two phases, one mobile and one immobile, fill the pore space. A simulated annealing algorithm determines the spatial distribution of the immobile phase. A finite amount (slug) of tracer is injected at a certain position of the domain and its concentration at the outlet is monitored with respect to time. The resulting response curves depend on the spatial distribution of the immobile phase, the diffusivity ratio and the relative solubility of the tracer in the two phases. A sensitivity study is performed to investigate the effect of the tracer partitioning coefficient and its diffusive properties in water and oil, on the predicted outlet concentration curve.
Effect of Subcooling on the Quenching of a Simulated Nuclear Fuel Rod
Authors: Sinha J. , Hochreiter L. E. , Cheung F. B. 
Published: November 2021

Abstract
An experimental study of the effect of liquid subcooling on the minimum film boiling temperature during quenching of a simulated nuclear fuel rod was performed under carefully controlled laboratory conditions. The rod was designed and fabricated with a proper combination of cladding and filler materials and was instrumented with embedded thermocouples distributed at various axial and radial locations. Quenching of the rods was done using distilled water with various degrees of subcooling as the working fluid. It was found that the rate of quenching depends strongly on the liquid subcooling. Multiple maxima were observed between film and nucleate boiling in the boiling curve for high subcoolings. Increasing subcooling had the effect of moving the entire boiling curve up and to the right, resulting in a considerably high minimum film boiling temperature. The strong effect of liquid subcooling on the quenching of a fuel rod should be properly accounted for in the study of reflood heat transfer in a nuclear reactor following a design-based accident.
Growth and Collapse of a Vapor Bubble Under Impulsive Heating
Authors: Prosperetti A. , Yuan He , Yin Zhizhong 
Published: November 2021

Abstract
In the first part of the paper a micropump based on the periodic growth and collapse of a single vapor bubble in a small channel is described. An explanation of the pumping principle and some preliminary experimental results are presented. In the implementation described the liquid is electrically conductive and is heated by passing a current through it; the same principle would be applicable to the case of non-conducting liquids by using heaters embedded in the channel walls. In the second part of the paper a model for the growth of a bubble onto a heater in a liquid is presented and some numerical results are discussed.
An Improved Time Domain Simulation for Dynamic Milling at Small Radial Immersions and Large Depths of Cut
Authors: Campomanes Marc L. , Altintas Yusuf 
Published: November 2021

Abstract
This paper presents an improved time domain model for milling, which can simulate vibratory cutting conditions at very small radial widths of cut and large depths of cut. The improved kinematics model allows simulation of very small radial immersions. The varying dynamics modeled along the cutting depth allows milling with very flexible cutters and/or flexible workpieces at very deep cuts to be simulated. The model can predict forces, surface finish, and chatter stability, accurately accounting for non-linear effects that are difficult to model analytically. The discretized cutter and workpiece kinematics and dynamic models are used to represent the exact trochoidal motion of the cutter, and to investigate the effects of forced vibrations and changing radial immersion due to deflection and vibrations on chatter stability. Three dimensional surface finish profiles are predicted and are compared to measured results. Stability lobes generated from the time domain simulation are also shown for various cases.
Using the Eigenvalues of Multivariate Spectral Matrices to Monitor Equipment
Authors: Roth John T. 
Published: November 2021

Abstract
There is a strong need in industry for monitoring techniques that are capable of tracking the health of cutting tools under varying conditions. Unfortunately, most monitoring techniques that are currently available are dependent on the cutting direction and/or the sensor orientation, limiting their effectiveness in the typical industrial environment. With this in mind, this research focuses on developing a monitoring technique that is independent of both of these factors. This is accomplished by using multivariate autoregressive models that are fit to the output from a tri-axial accelerometer. The work shows that the eigenvalues of multivariate spectral matrices, calculated at the machining frequencies, are sensitive to the condition of the tool. Furthermore, it is theoretically demonstrated that these eigenvalues are independent of the direction of cutting and the orientation of the sensor. This independence is verified experimentally through tests conducted under a variety of cutting directions and sensor orientations.
A Model for the Tool Temperature During Machining With a Rotary Tool
Authors: Kishawy Hossam A. , Gerber Andrew G. 
Published: November 2021

Abstract
In this paper a model is developed to analyze heat transfer and temperature distribution resulting during machining with rotary tools. The presented model is based on a finite-volume discretization approach applied to a general conservation of energy statement for the rotary tool and chip during machining. The tool rotational speed is modeled and its effect on the heat partitioning between the tool and the chip is investigated. The model is also used to examine the influence of tool speed on the radial temperature distribution on the tool rake face. A comparison between the predicted and previously measured temperature data shows good agreement. In general the results show that the tool-chip partitioning is influenced dramatically by increasing the tool rotational speed at low to moderate levels of tool speed. Also, there is an optimum tool rotational speed at which further increase in the tool rotational speed increases the average tool temperature.
Machining Simulation of Ductile Iron and its Constituents: Part II — Numerical Simulation and Experimental Validation of Machining
Authors: Chuzhoy L. , DeVor R. E. , Kapoor S. G. 
Published: November 2021

Abstract
To understand the influence of cast iron microstructure on its machinability, a numerical model that simulates machined material on a microstructure scale was developed. This microstructure-level model assembles individual constituents into a composite material based on microstructural composition, grain size, and distribution. Extensive experimentation was performed to determine strain, strain rate, temperature, and load history dependent material properties. The purpose of this work is to validate the microstructure-level model on machining of ductile iron and two of its constituents: pearlite and ferrite. Orthogonal cutting experiments were conducted of the three materials. The measured chip morphology and machining forces were compared with the model predictions, and a good correlation between them was found.
Stream of Variation Based Analysis and Synthesis of Measurement Schemes in Multi-Station Machining Systems
Authors: Djurdjanovic Dragan , Ni Jun 
Published: November 2021

Abstract
The choice of a measurement strategy in multi-station machining systems is crucial for subsequent successful identification of the root causes of machining errors. The measurement strategy selection is currently not a systematic process and it involves human and expert intervention. Recent advances in the linear state-space modeling of multi-station machining processes facilitate a more formal characterization of measurements in machining and a more systematic approach in the selection of the features that need to be measured. In this paper, we employ the Stream of Variation methodology to evaluate various measurement schemes in multi-station machining systems. Based on this evaluation, measurement synthesis procedures are presented, such that the resulting measurement scheme achieves a tradeoff between measurement uncertainty and the cost of measurements.
Heat Input Control in 3D Laser Cladding Based on Infrared Sensing
Authors: Hu Dongming , Wu Yunxin , Kovacevic Radovan 
Published: November 2021

Abstract
Solid Freeform Fabrication (SFF) methods for building metallic part, such as 3D laser cladding, are generally less stable and less repeatable than other rapid prototyping methods. The infrared image of the molten pool is a promising sensing technique for the closed-loop control of the cladding process. In this paper, the closed-loop control of heat input based on infrared image sensing in 3D laser cladding is introduced. A high frame-rate (up to 800frame/s) camera is installed coaxially at the top of the laser-nozzle setup. A full view of the infrared images of the molten pool can be acquired with a short nozzle-substrate distance in different scanning directions, eliminating the noise from the metal powder. The features of the images show a clear relationship with the variation of the cladding process parameters. The closed-loop control results show a great improvement in the geometrical accuracy and microstructure of the built part.
Development of the Cylindrical Wire Electrical Discharge Machining Process
Authors: Qu Jun , Shih Albert J. , Scattergood Ron 
Published: November 2021

Abstract
Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. The design of an underwater rotary spindle is first introduced. The spindle is added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometry. Mathematical models for material removal rate and surface finish in cylindrical wire EDM of the free-form cylindrical workpiece are derived. Experiments are conducted for cylindrical and 2D wire EDM of brass and carbide work-materials. Comparing to the conventional 2D wire EDM of the same work-material, higher maximum material removal rates could be achieved in the cylindrical wire EDM. The surface finish and roundness of parts generated by cylindrical wire EDM at different part rotational speeds and wire traverse speeds are measured and analyzed.
A Precision Alignment Method to &lt;100&gt; Direction on (110) Silicon Wafer
Authors: Tseng Fan-Gang , Chang Kai-Chen 
Published: November 2021

Abstract
This paper proposes a novel pre-etch method to determine the lt;100gt; direction on (110) silicon wafers for bulk etching. Series of circular windows were arranged in an arc of radius 48.9 mm, and bulk-etched to form hexagonal shapes for crystal orientation finding. The corners of the hexagons can be used as an alignment reference for the indication of the lt;100gt; direction on (110) silicon wafers. This innovative approach has been demonstrated experimentally to give an orientation-alignment accuracy of ± 0.03° for (110) wafers with 4-inch diameter.
The Resonant Micro Fan for Fluidic Transport, Mixing and Particle Filtering
Authors: Linderman Ryan J. , Sett Subham , Bright Victor M. 
Published: November 2021

Abstract
A novel micro actuator for fluidic transport, mixing and particle filtering is presented. The technology uses a torsionally supported plate driven with an electrostatic signal at first-mode resonance to produce long-term reliable fluidic interactions at the chip level. Resonant frequencies from 10–20kHz have been tested with maximum fan deflections of approximately 30 microns. The resonant fans are fabricated using surface micro-machining techniques and flip-chip assembly. A simple flow visualization technique is also presented using laser illuminated smoke particles contained within the device packaging. The flow visualization setup allows for both overhead and side views as well as infinite ceiling and channel flow simulation in order to fully characterize the three dimensional flow produced by the resonant fans. Flow speeds of over 10 mm/s have been observed to exit single micro fans with large fan arrays producing over 2mL/min of volumetric flow. Fan testing in 600-micron deep channels has demonstrated the potential for suspended particle collection and filtering applications.
A Sub-Millimeter Solenoid Device for Trapping Paramagnetic Microbeads
Authors: García Luis D. , Cheung Lawrence C. , Mikkelsen James C. , Santiago Juan G. , Bernhardt Anthony F. , Malba Vincent 
Published: November 2021

Abstract
We present the design and preliminary evaluation of a paramagnetic microsphere trapping and separation device consisting of a copper solenoid wrapped around a 1.3 mm diameter glass capillary. The magnetization and subsequent dipole-dipole interaction of paramagnetic spheres under an applied magnetic field results in the formation of bead chains that persist and grow under the applied field, but quickly disperse upon field removal. The chaining of paramagnetic spheres is important to the design of magnetic-based separation devices because the viscous-drag-limited velocities of chains are typically several times larger than that of individual particles. We have performed a set of experiments designed to evaluate the performance of a sub-millimeter solenoid device including measurements of the temperature versus field strength of the device, observations of the controlled chain formation process, and preliminary observations regarding the maximum flow rate over which the bead chains can be held in place by magnetic forces. These results are applicable to the design and characterization of magnetically induced microsphere trapping and separation systems which use pressure driven flow.
Pt Heater/Sensor Microarray for Distributed Fluidic Cooling Assessment
Authors: Yoon Yong-Kyu , Allen Mark G. 
Published: November 2021

Abstract
This paper presents the design, fabrication, and characterization of a one-dimensional microscale heater array testbed that allows assessment of the spatial variation of temperature. Each pixel of the array acts as both a heater and a resistive temperature sensor simultaneously. The heater/sensor array is designed to mimic heat generation by line arrays of vertical-cavity surface emitting lasers (VCSELs), in order to assess microfluidic cooling schemes for these laser arrays. The array discussed in this paper is a linear micro array consisting of 100 heater elements, each of which has a 75μm pitch, and a nominal 20μmx20μm resistive heating area. Platinum is used for the heater as well as the resistive thermal sensor, since the resistance of platinum as a function of temperature shows extremely good linearity. A total of 101 probe pads are placed between the pixels to apply current for the heater function or to determine temperature for the sensor function. The array is fabricated on a silicon substrate and is diced to a size of 1.2mm × 8mm to match a typical VCSEL array size. Local heating and local cooling experiments (i.e., individual heater pixel or pixel groups) have been performed and demonstrate the versatility of the fabricated thermal testbed.
Fabrication of an Electromagnetic Micropump for Cerebrospinal Fluid Shunt
Authors: Kim Myung Sik , Kwon Kee Young , Lee Sang Wook , Yang Sang Sik 
Published: November 2021

Abstract
This paper presents the design and fabrication of a micropump for cerebrospinal fluid shunt. The micropump is to be implanted in hydrocephalus patients, The micropump consist of a corrugated parylene diaphragm and a set of nozzle and diffuser. The electromagnetic force drives the diaphragm. The static or dynamic characteristics of the fabricated devices have been obtained experimentally. The size of the micropump is 14 × 12 × 8mm3. The increased flow rate of the micropump is about 50 μl/min at operational range.
Characterization of Drying Techniques for Micro-Stereolithography
Authors: Wu Dongmin , Fang Nicholas , Sun Cheng , Zhang Xiang 
Published: November 2021

Abstract
Micro-stereolithography (μSL) is an advanced technology that enables fabrication of highly complex three-dimensional polymer microstructures out of UV curable resin. However, releasing of polymerized structures from un-polymerized resin is found to influence substantially the fabrication reliability of μSL, as the surface tension tends to push the fine structures together and cause collapse or adhesion. A theoretical model is developed to analyze the deflection and adhesion between thin polymer beams under capillary force. The detachment length of the test structures and solid surface tension of a typical μSL polymer (HDDA) are obtained experimentally. In this paper, we applied sublimation process to overcome the adhesion problem With the new drying process, no adhesion phenomenon was observed.
Sound Radiation From a Flow-Excited Rectangular Plate With Visco-Elastic Supports
Authors: Park Junhong , Siegmund Thomas , Mongeau Luc 
Published: November 2021

Abstract
In road vehicles, one dominant “wind noise” generating mechanism is the flow-induced vibration of side-glass windows. Side-glass windows are excited by unsteady surface pressures associated with turbulent flows over the vehicle body. In this study, experiments were performed in order to investigate the sound radiated by a seal-supported, rectangular aluminum panel excited by separated/reattached flow. The primary goal of this investigation was to assess the influence of seal mechanical properties and geometries on the sound transmission loss of the side-glass window. Experimental modal analysis test was conducted to accurately measure the resonance frequencies and the modal damping ratios of the panel. Surface pressure measurements were performed using small-diameter condenser microphones. The influence of the excitation spectrum on the radiated noise level was determined. The results were compared with theoretical predictions obtained using an analytical model based on a variational formulation of the problem. The flow-excited vibration response was predicted accurately for two different turbulent flows. The vibration energy dissipation at the sealing system reduced the amplitude of the plate vibration at resonance and the radiated sound.
Shape Sensitivity Analysis Applied to Exterior Acoustics
Authors: Feijóo Gonzalo R. , Oberai Assad A. , Pinsky Peter M. 
Published: November 2021

Abstract
We present a method to calculate the derivative of a functional that depends on the shape of a body immersed in an acoustic media. The functional depends implicitly on the shape through the solution of an exterior acoustic problem. The derivative is calculated in terms of the solution of the primal problem and an auxiliary problem, the adjoint problem. An important aspect of this method is that the cost of calculating the derivative is independent of the number of parameters used to represent the shape of the body. This allows for efficient solution of optimization problems in structural acoustics.