bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flash-Boiling Characterization During Ingress of Coolant Event for Dust Issue in ITER
Authors: Blaisot Benjamin , Porcheron Emmanuel , Praud Olivier , Roig Véronique 
Published: February 2022

Abstract
Dust resuspension inside the vacuum vessel (VV) is one of the safety issues of the fusion reactor ITER. Plasma interaction with the plasma facing components (PFC) leads to their erosion, generating dust. One of the accident scenarios leading to dust resuspension is the ingress of coolant event (ICE) where a leak of the coolant pipes inside the VV conducts to injection and flash atomization of the cooling water. The metallic dust, produced by the erosion, is then oxidized by water throughout an exothermic reaction that produces hydrogen leading to a loss of confinement risk due to hydrogen and dust combustion. The steam flow, produced by the flash atomization of the liquid leaking from the breach, is considered to be the main source of dust resuspension. Therefore, experimentations about the two-phase flow generated by the flashing liquid jet are important to identify the main physical phenomena involved in the aerosol particles resuspension for ITER-like conditions that impose in particular low pressure level. Flash-boiling experiments were conducted under primary vacuum conditions. We studied the behavior and the structure of the flow resulting from superheated water injection into low pressure environment. Using shadowgraphy and particle image velocity (PIV), qualitative information and quantitative measurements on the two-phase flow that develops for different superheat conditions were gathered. The measured spray lateral spreading and droplets velocity are shown to increase with the superheat level. The use of a transparent nozzle also confirmed the strong coupling between the external structure of the atomized spray and the two-phase flow that develops upstream of the coolant circuit breach.
Steady-State Subchannel Thermalhydraulic Assessment of a Full-Scale Pressurized Water Reactor-Small Modular Reactor Fuel Assembly With Conventional and Advanced Fuels
Authors: Bayomy Ayman M. , Bromley Blair P. , Nava Dominguez Armando , Kelly Samuel 
Published: February 2022

Abstract
Thermalhydraulic analyses using subchannel codes (e.g., ASSERT-PV) are performed as a support tool to evaluate safety margins and the key parameters. Advanced fuels have recently attracted the international community's interest to improve safety margins during normal operation and accident scenarios by utilizing special coatings and barriers in a heterogeneous, multiregion, multicoating, multiclad annular fuel. In addition, advanced fuels improve the performance characteristics such as a higher burnup and better uranium utilization. Therefore, there is a need to understand the implications of such advanced unconventional fuels for the landscape of the Canadian nuclear industry and Canadian policy for energy development. In this work, subchannel thermalhydraulic analysis of a small modular reactor based on pressurized water reactor technology (PWR-small modular reactor (SMR)) core is performed using ASSERT-PV. A benchmark of a 17 × 17 fuel assembly with conventional fuel elements in comparison to PWR-SMR specification was conducted. The advanced fuel element system is also investigated and compared with the conventional one. The results indicated that the advanced fuel achieves a significant reduction in fuel element temperature by 15%. In addition, the results revealed that the proposed advanced fuel could achieve a minimum critical heat flux ratio (MCHFR) higher than the conventional fuel by 17%.
Transient Charging Characteristics of Shell and Tube Latent Heat Storage System—A Novel Two-Dimensional Analytical Approach
Authors: Agrawal Abhishek , Rakshit Dibakar 
Published: February 2022

Abstract
Energy storage using latent heat of solid–liquid phase change material (PCM) is an efficient option due to high energy density and low volume variation during phase change. Such type of storage is suitable to exploit untapped solar energy and waste heat energy. The present work explores the analytical approach to study the unsteady charging behavior of PCM inside latent heat thermal energy storage (LHTES) system. The radial, axial as well as temporal effects on the melting of PCM are investigated analytically. Relation between time, temperature, radius, and axial distance of storage system is developed using energy equation in cylindrical coordinates. The 49% reduction in melting time of PCM was noted with an increase in heat transfer fluid inlet temperature from 185 °C to 200 °C. It was also observed that melt front moves 1.28 times faster when axial position changes from 100 mm to 200 mm. Convection heat transfer plays a vital role during the charging process, and it is found that the melt front moves radially outward and axially upward during the melting of PCM. It can also be concluded that analytical tools like the one presented in this study can be instrumental in analyzing the thermal performance of storage units.
Effect of a Ceramic Matrix Composite Surface on Film Cooling
Authors: Wilkins Peter H. , Lynch Stephen P. , Thole Karen A. , Vincent Tyler , Quach San , Mongillo Dominic 
Published: February 2022

Abstract
Ceramic matrix composite (CMC) parts create the opportunity for increased turbine entry temperatures within gas turbines. To achieve the highest temperatures possible, film cooling will play an important role in allowing turbine entry temperatures to exceed acceptable surface temperatures for CMC components, just as it does for the current generation of gas turbine components. Film cooling over a CMC surface introduces new challenges including roughness features downstream of the cooling holes and changes to the hole exit due to uneven surface topography. To better understand these impacts, this study presents flowfield and adiabatic effectiveness computational fluid dynamics (CFD) for a 7–7–7 shaped film cooling hole with a 5 Harness Satin CMC weave at two orientations. To understand the ability of steady RANS to predict flow and convective heat transfer over a CMC surface, the weave surface is initially simulated without film and compared to previous experimental results. The simulation of the weave orientation of 0 deg, with fewer features projecting into the flow, matches fairly well to the experiment and demonstrates a minimal impact on film cooling leading to only slightly lower adiabatic effectiveness compared to a smooth surface. However, the simulation of the 90-deg orientation with a large number of protruding features does not match the experimentally observed surface heat transfer. The additional protruding surface produces degraded film cooling performance at low blowing ratios but is less sensitive-to-blowing ratio, leading to an improved relative performance at higher blowing ratios, particularly in regions far downstream of the hole.
Micro-Stereolithography for MEMS
Authors: Zhang X. , Jiang X. N. , Sun C. 
Published: February 2022

Abstract
Micro stereolithography (μSL) is a novel micro-manufacturing process which builds the truly 3D microstructures by solidifying the liquid monomer in a layer by layer fashion. In this work, an advanced micro stereolithography (μSL) apparatus is designed and developed which includes an Ar+ laser, the beam delivery system, computer-controlled precision x-y-z stages and CAD design tool, and in situ process monitoring systems. The 1.2 μm resolution of μSL fabrication has been achieved with this apparatus. The micro tubes with high aspect ratio of 16 and real 3D microchannels and micro cones arc fabricated on silicon substrate. For the first time, micro stereolithography of ceramic micro gears has been successfully demonstrated.
An Implicit Numerical Model for Electrophoretic Systems
Authors: Giridharan M. G. , Krishnan Anantha 
Published: February 2022

Abstract
An implicit finite-volume approach has been developed to solve the equations governing the electrophoretic process. The numerical procedure involves the sequential solution of the species conservation ionization equilibria and electro-neutrality equations in an iterative fashion until convergence. This implicit procedure is numerically stable and allows for faster steady-state solutions or larger time steps for time-accurate simulations. Temporal evolutions of pH, species concentrations and electrolyte conductivity are predicted. The results obtained using various higher order numerical schemes are compared and assessed. Results are presented for the isoelectric focussing, moving boundary electrophoresis, and capillary electrophoresis of amino acids and a protein. The predictions for the isoelectric focussing of albumin protein are in qualitative agreement with published experimental data.
Peristaltically Driven Flows for Micro-Mixers
Authors: Selverov Kiril P. , Stone Howard A. 
Published: February 2022

Abstract
Flows driven by a transverse travelling wave, propagating along a boundary of a closed rectangular container are examined, motivated by mixing with applications in MEMS. The steady, time-independent flow is computed analytically in the asymptotic limit of high frequencies and the boundary-layer structure is described. The results could be useful for modeling devices where streaming fluid motion needs to be produced without any internal moving parts.
Fabrication and Testing of a Multilayer Silicon Fluidic Laminar Proportional Amplifier
Authors: Piekarski Brett H. , Zeto Robert J. , Tenney Steve M. , Ervin Matthew H. 
Published: February 2022

Abstract
A multilayer fluidic laminar proportional amplifier (LPA) was fabricated from silicon wafers by using state-of-the-art photolithography and silicon deep-reactive ion-etching (DRIE) technologies. The assembled silicon amplifier showed a factor of 10 improvement in null offset when compared to an amplifier fabricated with traditional stainless steel laminates. Null offset is a measure of fabrication quality.
The pressure gain, which is a measure of performance, of the silicon amplifier was lower than expected. The low gain values resulted from a more faithful fabrication of the selected LPA design in silicon, producing a constricted flow condition. The same condition did not exist in the traditional stainless steel amplifier because patterning and overetching of the control features during photochemical milling widened the gap between the control edges beyond the designed value. The fabrication capability of the DRIE process has forced a reevaluation of the current LPA design.
Collection of Airborne Bacteria With Micro-Machined Virtual Impactor Arrays
Authors: Kenning Vanessa M. , Call Charles J. , Call Patrick T. , Birmingham Joseph G. 
Published: February 2022

Abstract
Collection of airborne bacteria (bioaerosols) is of interest for a variety of public health and national security concerns. A novel microfabricated virtual impactor device is being developed to concentrate bioaerosol particles in the 1 to 3 micron size range, which is typical of a single bacterial spore. The concentration is from a large to a small volume of air, with target concentration factors between 5 and 50. A virtual impactor uses the particle’s inertia to separate it from the main flow stream. Our design represents a significant departure from existing virtual impactor technology: the particle laden flow is directed into planar rows of virtual impactor elements. This novel architecture is described in detail in this paper. The use of computational fluid dynamics has led to designs in which each impactor row is specialized. Polystyrene latex (PSL) spheres simulate the bioaerosol particulates in our experiments. The experimental results show trends that do not correlate with the simulations. The data support our hypothesis that surface roughness may result in turbulent mixing within the virtual impactor elements, thereby reducing the effectiveness of the concentrator. Additional study of the effect of surface roughness and turbulence within the virtual impactor is planned.
Development of an Electromagnetically Actuated Mercury Microvalve
Authors: Adkins Douglas R. , Wong C. Channy 
Published: February 2022

Abstract
The development of microscale fluid handling components has been recognized as a crucial element in the design of microscale chemical detection systems. Recently, work has been undertaken at Sandia National Laboratories to construct a valve that uses a small mercury droplet to control the flow of gas through capillary passages. Electromagnetic forces that are provided by small permanent magnets and a current supply are used to drive the mercury into position. Driving the mercury droplet into a tapered passage halts gas flow through a capillary, while surface tension forces prevent the mercury from passing through the passage. Models have been developed to describe the movement of the mercury droplet and the sealing of the gas passage, and millimeter-scale units have been tested to explore design options. Predictions from the model show that a valve with 10 micron sized features can seal against pressures up to 1.5 atmospheres. Experiments have highlighted the promise of mercury valves and demonstrated problems that can arise from contamination of the mercury.
3-Way Microvalve for Pneumatic Applications Fabricated by Silicon Micromachining
Authors: Messner Stephan , Müller Martin , Schaible Jochen , Sandmaier Hermann , Zengerle Roland 
Published: February 2022

Abstract
A new normally-closed 3-way microvalve for pneumatic applications is presented. The valve is driven by a bimetallic actuation principle. This paper will discuss the dimensioning and design, the fabrication and the experimental results of the 3-way valve. The valve is designed to control differential pressures of 1000 kPa. Flow rates up to 800 ml/min for dry air at 600 kPa can be achieved. The power consumption is approximately 1.5 W. The valve has been tested successfully in an ambient temperature ranging from 0° to 50°C.
A Pneumatic Frequency Generator for Experimental Analysis of Unsteady Microflows
Authors: Colin Stéphane , Anduze Marc , Caen Robert 
Published: February 2022

Abstract
It is shown that the frequency analysis of pneumatic microchannels is experimentally limited to low frequencies, because of the large difference between the microchannels and the current pressure sensors areas. From this remark, a new pneumatic low-frequency generator has been devised. Firstly, the good quality of the sinusoidal pressure signal has been checked. Secondly, first experimental data have been obtained for microtubes about 100 μm in diameter; regarding the gain and the phase of the pressure signal, they show a good agreement with a previously elaborated model. Finally, the feasibility of performing measurements on smaller microchannels, with hydraulic diameters about 1 μm, has been demonstrated. Since it requires to associate several microchannels in parallel, first experimental measurements with a few microtubes in parallel have been made; they have confirmed theoretical predictions, with discrepancies in the same region as for data about millimetric systems reported in the literature.
General Contact and Hysteresis Analysis of Multi-Dielectric MEMS Devices Under Thermal and Electrostatic Actuation
Authors: He Yie , Marchetti James , Gallegos Carlos 
Published: February 2022

Abstract
Many MEMS devices which are thermally and/or electrostatically actuated contain moveable components which may undergo contact. The behavior is further complicated when hysteresis is exhibited after contact [1,2]. Generally, MEMS devices consist of multiple materials with different mechanical and electrical properties. These factors pose a challenge for modeling highly non-linear MEMS behavior.
This paper presents an improved approach to modeling contact and hysteresis between any two bodies in a MEMS device. In particular, the three assumptions are relaxed. First, previous methods for modeling contact were able to model only a single dielectric layer. The new approach is capable of modeling multi-dielectric layers. Second, previous modeling methods required the specification of contact faces. This restriction has been generalized to specifying contact entities. Third, previously, modeling methods required an air stop gap assumption above a conductor to avoid numerical difficulties in electrostatic calculations. The new approach developed removes the air stop gap assumption. More realistic mechanical contact is emulated. Electrostatic and thermal driven actuation is considered.
A number of case examples is presented to demonstrate the utility of the new contact and hysteresis approach. First a suspended test-beam structure is analyzed under different sets of boundary constraints and loading. Then, contact of an electrostatically actuated deformable mirror is analyzed.
Fabrication of 109.5° Micro V-Grooves Using a Two-Step Anisotropic Etching Technique
Authors: Chien Wen-Tien Chang , Lin Liwei , Lo Yi-Chung , Chang Chia-Ou 
Published: February 2022

Abstract
Design and fabrication of 109.5° V-grooves based on two-step anisotropic etching techniques are demonstrated and reported. This new process can expose planes other than the commonly used {111} surfaces to form new geometrical shapes. V-grooves of 109.5° are demonstrated by etching and exposing {112} planes on (100) wafers with anisotropic KOH etchants. Theoretical foundations are analyzed with experimental verifications. This new class of two-step etching process extends the capability of MEMS manufacturing to make new geometrical shapes and may have potential applications for device fabrications that requires non-conventional contours.
A Constrained Thermal Expansion Micro-Actuator
Authors: Cragun Rebecca , Howell Larry L. 
Published: February 2022

Abstract
This paper describes a series of thermal micro-actuators fabricated from polycrystalline silicon. These actuators use geometric constraints to amplify motion from thermal expansion. Compliant mechanism theory, particularly the pseudo-rigid-body model, was used to aid in the visualization of the device’s behavior. Nonlinear finite element analysis was used to analyze the actuators and refine the designs. The resulting mechanisms were fabricated and tested. Maximum deflections of over 20 μm were obtained with a total cycle time faster than 4 milliseconds. A bi-directional actuator capable of 6 μm displacements in both directions is also described.
Mechanical Optimization of a Dual-Axis Piezoresistive Force Sensor
Authors: Liang Yiching , Kenny Thomas 
Published: February 2022

Abstract
Micromachined cantilevers have been demonstrated to be effective measuring devices for small forces and displacements. Applications for such micro-electro mechanical systems include imaging of surface topography, data storage, and atomic force microscopy (AFM). Researchers at Stanford University have developed a piezoresistive sensor with independent vertical and lateral force detection capability using oblique ion implantation and high aspect-ratio plasma etching [1–3]. An SEM image of the device is shown in Figure 1. Although this device has been successfully used to obtain data and for servo control of a tracking system for a data storage device, its mechanical behavior has not been carefully studied. This device can be used to measure forces or deflections in various applications. This paper demonstrates how the device performance can be optimized for a specific set of requirements. Applications with different stiffness or bandwidth requirements may be designed using similar methods.
Ceramic Tape-Based Meso Systems Technology
Authors: Bau Haim H. , Ananthasuresh Suresh G. K. , Santiago-Avilés Jorge J. , Zhong Jihua , Kim Moon , Yi Mingqiang , Espinoza-Vallejos Patricio , Sola-Laguna Luis 
Published: February 2022

Abstract
Ceramic tape technology was initially developed for efficiently manufacturing interconnects and hybrid microelectronics circuitry through sequential printing and firing of conductor, resistor and/or dielectric paste formulations onto a substrate. Recently, it has been recognized that ceramic tapes can also be used as an efficient and convenient medium for the manufacturing of meso-scale electro-mechanical systems. In the green (pre-fired) state, the ceramic tapes consist of alumina particles, glass frit, and organic binder; and they are soft, pliable, and easily machinable. In each layer, one can machine flow conduits and mechanical devices and print electronic circuits. Very many layers can be stacked together to form complicated, three-dimensional, monolithic structures. These layers can be laminated and sintered. During the sintering process, the organic binder burns out, the glass flows, and the material hardens. It is possible to cast tapes of various ceramic composition to obtain desirable properties.
The paper describes mechanical, chemical, and thermal machining of prefired Low Temperature Co-fired Ceramic Tapes (LTCC); the dimensional changes occurring during the lamination and sintering processes; the use of sacrificial layers to prevent the sagging of internal suspended structures during the lamination and firing processes; the bonding of tapes to alumina, silicon, glass, and metals to form a hybrid technology; and the manufacturing of microchannels and a flow sensor in ceramic tapes.
Packaging is widely considered to be the Achilles heel of silicon-based MEMS technology since it is difficult to interface silicon MEMS devices with each other and fabricate relatively large, three-dimensional structures. Low Temperature Co-fired Ceramic Tapes (LTCC), the packaging material of choice in the electronics industry, hold the promise of alleviating some of these difficulties.
Self-Assembled Microslider for Microjoinery
Authors: Huang L.-S. , Sridharan B. , Kim C.-J. , Collins S. D. , González C. , Smith R. L. 
Published: February 2022

Abstract
MicroJoinery is an attractive concept to create precise translational movement for such components as optomechanical micro-accessories due to the readiness of silicon etching techniques. Basic fabrication of the dovetail MicroJoints uses anisotropic etching of (100) silicon wafers and fusion bonding. This paper focuses on a new fabrication method of self-assembly of the translational stage using a sacrificial layer and an electroplated microriveting technique, eliminating the need for wafer bonding and manual assembly. The slider is made from a double-side polished wafer and slides on substrate guided by a guide rail. The clearance between the sliding parts defined by the thickness of sacrificial layer is much smaller and repeatable than what bulk micromachining and manual assembly could provide. The coefficient of static friction was measured to be 0.42–0.78 in air for the self-assembled microslider with an added weight (3.5 g). For manually assembled dovetail MicroJoinery devices coated with silicon nitride, friction coefficient of around 0.302 was obtained.
Design and Fabrication of an Electrostatic Variable Gap Comb Drive in Micro-Electro-Mechanical Systems
Authors: Ye W. , Mukherjee S. 
Published: February 2022

Abstract
Polynomial driving-force comb drives are synthesized using numerical simulation. The electrode shapes are obtained using the indirect boundary element method. Variable gap comb drives that produce combinations of linear, quadratic, and cubic driving-force profiles are synthesized. This inverse problem is solved by an optimization procedure. Sensitivity analysis is carried out by the direct differentiation approach (DDA) in order to compute design sensitivity coefficients (DSCs) of force profiles with respect to parameters that define the shapes of the fingers of a comb drive. The DSCs are then used to drive iterative optimization procedures. Designs of variable gap comb drives with linear, quadratic and cubic driving force profiles are presented in this paper. Based on these designs, a comb drive which produces cubic polynomial driving force has been fabricated using the SCREAM I process.