bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wind Tunnel Investigation and Numerical Analysis of Fume Behavior in the Vicinity of Rectangular Building Under Moderate Velocity Wind
Authors: Mahjoub Hammouda , Abdulkadhim Ammar , Ben Romdhane Sahar , Mahjoub Said Nejla , Bournot Hervé , Mejbel Abed Isam 
Published: February 2022

Abstract
A research was conducted to examine the dispersion of pollutants ejected from a chimney around three-dimensional rectangular building. Regarding the experimental study, the wind tunnel experiment comprises data acquired through the dispersion of continuous source tracer discharges from a punctual source situated in a regular network of building-like obstacle, and these data include measurements of mean velocity and turbulence parameters. The relevant data are followed using Particle Image Velocimetry to track various instantaneous and mean dynamic characteristics. Concerning the numerical study, the suggested model simulates both the dynamics and the heat transfer flow field using the overall mean three-dimensional Navier-Stokes equations with an RSM turbulence closure model. The findings of a deep comparison of turbulent flow and dispersion between a full wind tunnel experiment and the model predictions are reported. A high degree of concordance was obtained with the experimental flow and numerical simulation data. The detailed investigation, in which numerical and wind tunnel studies, was performed to evaluate the impact of wind velocity on the pollutant dispersion issued from a chimney around the building in their vicinity. the results clearly showed how wind velocity influenced the environmental air flows and pollutant dispersal pathways. The results of this study show that the shape of the building and the resulting interaction between the wind structure play a determining factor in the distribution of pollutants around a building, thereby affecting the air quality in the various parts of the building.
Experimental Investigation of the Pre-Stall and Stall Evolution in a Centrifugal Compressor With a Volute
Authors: Zhang Hanzhi , Yang Ce , Wang Wenli , Yang Changmao , Li Yanzhao 
Published: February 2022

Abstract
Stall and surge behaviors deteriorate the compressor performance and stability of the operating range. To avoid the effect of stall and surge behaviors, the characteristics of the pre-stall disturbance have been considered in recent years. However, investigations of the pre-stall and stall disturbances in centrifugal compressors remain insufficient owing to the various geometric structures in centrifugal compressors. In this study, a centrifugal compressor with a volute and vaneless diffuser was studied using high-response static pressure measurements and numerical simulations. The pressure disturbance evolution from near-choke to near-surge conditions was obtained, and the characteristics of the pre-stall and stall disturbances were analyzed. The results showed that the compressor instability route could be divided into pre-stall and stall stages, which could be accurately predicted based on the periodic static pressure irregularity and skewness. The pre-stall stage was dominated by the rotating instability (RI) phenomenon, and the frequency of the RI was 43% of the blade passing frequency at 70% Nmax. The experimental results demonstrated that the first onset of RI occurred at the 120 deg–180 deg circumferential position and maintained a local pattern; then, RI occurred over the whole annulus when the flowrate was decreased. RI was induced by the vortex structure attached to the casing wall, leading to a sharp pressure trough in the static pressure trace. The RI exhibited an evolution pattern of initially increasing and then fading, which can be explained by the enlargement and movement of the impeller inlet vortex. The large blockage effect of RI triggered a stall with disturbances at 20% and 80% of the impeller shaft frequency, and these disturbance frequencies had a trend of shifting to one dominant frequency of 22% the impeller shaft frequency. Furthermore, stall cell merging and the coexistence of RI/stall phenomena occurred during the stall stage.
A Microinjector Free of Satellite Drops and Characterization of the Ejected Droplets
Authors: Tseng Fan-Gang , Kim Chang-Jin “CJ” , Ho Chih-Ming 
Published: February 2022

Abstract
This paper presents the droplet characteristics of a newly developed thermally driven microinjector, which uses asymmetric bubbles to increase the injection frequency significantly. Through special heater and chamber design, bubbles are generated to surround the nozzle in such a way to cut off the droplet tail and eliminate satellite droplets. Visualization systems are developed to verify the droplet ejection free of satellite droplets and to characterize the ejection and trajectory. A simple Stokes-flow model is also used to estimate the droplet ejection trajectory.
A Simple and Flexible Micro Reactor for Investigations on Heterogeneous Catalytic Gas Phase Reactions
Authors: Veser G. , Friedrich G. , Freygang M. , Zengerle R. 
Published: February 2022

Abstract
Micro reactors, i.e. chemical reactors with characteristic dimensions in the sub-millimeter range, hold great promise for novel chemical process routes (Lerou 1996, Wengeng 1996). Among their potential advantages for chemical processes are: the very small thermal inertia, allowing for a very direct control of temperature as a very critical reaction parameter; their inherent safety due to both the small reactant volume being present at any time in the reactor and the well controllable reactor and reaction conditions; and their small dimensions, making them easy to integrate into existing processes or to use them where space requirements are critical. Furthermore, for heterogeneously catalysed gas phase reactions, micro reactors offer the additional advantage of allowing for a very large surface to volume ratio. This should at least theoretically allow for an effective suppression of homogeneous gas phase reactions, since free surfaces typically are strong sinks for radical species which are required to keep the homogeneous reaction alive. Therefore, it should be possible to conduct a heterogeneously catalysed reaction involving a mixture of potentially flammable (if not explosive) gases in a micro reactor without any danger of open flames and explosion. This has the two-fold advantage, that not only the reaction becomes intrinsically safe, but it should also be possible to study heterogeneously catalysed high-temperature reactions without influences by parallel homogeneous reaction Pathways, making it a very valuable tool for research into this class of reactions.
Design, Testing, and Simulation of Microscale Gas Chromatography Columns
Authors: Hudson Mary L. , Kottenstette Richard , Matzke Carolyn M. , Frye-Mason Greg C. , Shollenberger Kim A. , Adkins Doug R. , Wong C. Channy 
Published: February 2022

Abstract
A microscale gas chromatography column is one component in a microscale chemistry laboratory for detecting chemical agents. Several columns were fabricated using the Bosch etch process which allows deep, high aspect ratio channels of rectangular cross-section. A design tool, based on analytical models, was developed to evaluate the effects of operating conditions and column specifications on separation resolution and time. The effects of slip flow, channel configuration, and cross-sectional shape were included to evaluate the differences between conventional round, straight columns and the microscale rectangular, spiral columns. Experimental data were obtained and compared with the predicted flowrates and theoretical number of plates. The design tool was then employed to select more optimum channel dimensions and operating conditions for high resolution separations.
Modification of Golay’s Theory for Rectangular Microfabricated Gas Chromatographic Columns
Authors: Spangler Glenn E. 
Published: February 2022

Abstract
The effect of band broadening in gas chromatography is specified by the height-equivalent-to-a-theoretical-plate (HETP) for the column. The HETP takes into account both longitudinal diffusion and resistance-to-mass-transfer in the gas and liquid phases. The original theory supporting HETP calculations was developed by Golay in 1958. Golay developed his theory for open-tubular and square columns, but not rectangular columns. This paper describes modifications that can be applied to Golay’s theory to address band broadening in a microfabricated rectangular column. For a given column length, microfabricated columns can have lower HETP’s than conventional capillary columns. A good rule of thumb is that resolution can be adjusted by selecting the column depth (provided it is much less than the column width), and the volumetric flow of carrier gas can be adjusted by selecting the cross-sectional area. A satisfactory compromise for operating parameters is to use a low inlet pressure that also provides an HETP that remains constant over a range of pressures.
Experimental Characterization of Printed Circuit Board-Based Cantilever Air Valves
Authors: Cheung Patrick , Berlin Andrew A. , Biegelsen David K. , Jackson Warren B. , Lau Rachel 
Published: February 2022

Abstract
In recent years there has been an emerging interest in the design, fabrication, and application of distributed air valves. Electrostatic cantilever air valves that are fabricated within a PC board process offer advantages such as low cost fabrication and potential for system integration. This paper reports on the operation and dynamics of these PCB valves. The experimental work focused on valve parameters such as cantilever flap size, material, thickness, orifice size, and dielectric thickness. Certain combinations of parameters were examined for real world operation including their flow handling capacity, switching speeds, voltage requirements, and durability. Valves that were fabricated in this work could switch in milliseconds, undertake hold-back pressures of over 2 KPa, and switch flows of over 6 SCFH. The hysteretic switching behavior is suitable for passive matrix addressing of arrays of such valves. Lifetimes exceeding 1 million cycles have been demonstrated.
Simulation and Design of Electro-Thermally Actuated MEMS Devices: A Case Study — The AFIT Piston Micromirror
Authors: Ghaddar Chahid K. , van Kuijk Joost , Gilbert John R. , Cowan William D. , Butler Jeffrey T. , Bright Victor M. 
Published: February 2022

Abstract
A finite element model has been developed using MEMCAD4.0 for the AFIT electrothermally actuated piston micromirror fabricated in the MCNC MUMPs 17 run. The model is used to quantify the residual stress in the mirror metal reflector and to simulate the mirror deflection and curvature both in vacuum and in nitrogen ambient. The numerical results are in good agreement with the measured values. The model is also used to predict the effect of the residual stress in the mirror supporting legs on the mirror deflection.
Genetic Algorithms in MEMS Synthesis
Authors: Li Hui , Antonsson Erik K. 
Published: February 2022

Abstract
Initial results have been obtained for automatic synthesis of MEMS mask-layouts using a genetic algorithm. An initial random population of mask-layouts is produced. An initial fabrication process sequence is also generated. The fabrication of each geometrically valid layout is simulated using a 3-D simulation of etching. The 3-D results of the fabrication simulation are compared to the desired 3-D shape. Resulting 3-D shapes that are determined to be sufficiently close to the desired shape are kept in the candidate population. A genetic algorithm is applied to each member of the remaining population of mask-layouts (and fabrication processes) to introduce random shape (and process) variations. The procedure is then repeated until one or more simulated shape is sufficiently close to the desired shape to stop the iteration.
Integrated Modeling and Testing of a Micro Hinged Structure for Sliding Friction Measurement
Authors: Redmond James M. , de Boer Maarten P. , Michalske Terry A. 
Published: February 2022

Abstract
This paper summarizes the design, modeling, and initial evaluation of a hinged structure for friction measurement in surface micromachining technology. While the area requirements are small, the present structure allows a much larger velocity and pressure range to be evaluated as compared to comb drive structures. The device consists of a cantilevered driver beam connected to a friction pad through a strategically located hinge. AC excitation of the beam flexure forces axial sliding of the friction pad due to beam foreshortening. Normal force is controlled by DC voltage on wings adjacent to the friction pad. While the achievable slip is small (10–30 nm), it is sufficient to disengage contacting asperities and engage new points of contact, and thus should be representative of frictional processes. Furthermore, the design enables the friction pad contact area to remain relatively constant over the excitation cycle. Computer simulation results are provided to mimic on-going experimental work. Increased friction forces are shown to enhance the size of hysteresis loops relating beam deflection to driver voltage.
Contact Resistance Modeling and Measurements of an Electrostatically Actuated Micromechanical Switch
Authors: Majumder Sumit , McGruer N. E. , Zavracky Paul M. , Morrison Richard H. , Adams George G. , Krim Jacqueline 
Published: February 2022

Abstract
An electrostatically actuated, surface micromachined microswitch is being developed and tested in the Microfabrication Laboratory at Northeastern University. In its simplest form, the microswitch consists of a nickel cantilever beam (approximately 70 :m long, 30 :m wide, and 2 :m thick), and three electrical terminals (made of gold), analogous to the drain, source and gate of an FET. Application of an actuating voltage between the gate electrode and the beam pulls the beam down so that the free end makes contact with the drain. The beam is fabricated with two or more miniature bumps at its end, with the objective of concentrating the contact force over a small area. The contact bump has a thin coating of electroplated gold creating a gold-on-gold electrical contact. Devices fabricated so far, have demonstrated threshold voltages of less than 30 V, long switching life (&gt; 109 switch cycles in a nitrogen ambient), low on-resistance (&lt; 1 ohm contact resistance), while carrying currents of 10 mA. The off-impedance exceeds 1012 Ohm. One of the primary objectives at this point is to understand the contact resistance characteristics. Contact resistance measurements are presented and compared with the results of a multi-asperity contact model of contact resistance.
Design and Fabrication of Piezoresistive Cantilever Microaccelerometer Arrays With a Symmetrically Bonded Proof-Mass
Authors: Ko Jong Soo , Cho Young-Ho , Kwak Byung Man , Park Kwanhum 
Published: February 2022

Abstract
This paper presents the production-oriented design and microfabrication process of a piezoresistive cantilever-beam microaccelerometer with a symmetrically bonded proof-mass. The symmetrically bonded proof-mass structure is devised not only for improving the production yield, but also for reducing the transverse sensitivity of the accelerometer. The accelerometers are batch fabricated in arrays, from which individual devices are obtained by wafer sawing process. The microfabricated accelerometer shows a resonant frequency of 2.15kHz and a sensitivity of 34μV/g/V within a nonlinearity of 2% over ±30g range at 100Hz. The structure and fabrication processes of the present accelerometer provide practical and effective means for the mass production of accelerometers with high reproducibility.
Utilization of Standard CMOS Layers for Microchannels
Authors: Rasmussen Angela , Locascio Laurie E. , Gaitan Michael , Zaghloul Mona E. 
Published: February 2022

Abstract
In this paper we describe two different methods to create microchannels using the standard CMOS integrated circuit process. Two different types of channels are demonstrated. One channel is surface micromachined to create a small depth channel. The other channel is bulk micromachined to realize a large depth channel. Each channel can have variable length and width. The shallow channel has a fixed depth that is dependent on the thickness of the standard metal layers in CMOS. The larger depth channel is controllable with a minimum depth of 30μm. The advantage of this process is that sensors, actuators, and electronics are very easily integrated with the microchannels.
A High Performance Hand-Held Gas Chromatograph
Authors: Yu Conrad M. , Lucas Matthew , Koo Jackson C. , Stratton Paul , DeLima Terri , Behymer Elaine 
Published: February 2022

Abstract
The Microtechnology Center of Lawrence Livermore National Laboratory has developed a high performance hand-held, real time detection gas chromatograph (HHGC) by Micro-Electro-Mechanical-System (MEMS) technology. The total weight of this hand-held gas chromatograph is about 5 lbs., with a physical size of 8″ × 5″ × 3″ including carrier gas and battery. It consumes about 12 watts of electrical power with a response time on the order of one to two minutes. This HHGC has an average effective theoretical plate of about 40k. Presently, its thermal sensitive detector at PPM limits its sensitivity.
Like a conventional G.C., this HHGC consists mainly of three major components: 1) the sample injector, 2) the column, and 3) the detector with related electronics. The present HHGC injector is a modified version of the conventional injector. Its separation column is fabricated completely on silicon wafers by means of MEMS technology. This separation column has a circular cross section with a diameter of 100 μm. The detector developed for this hand-held G.C. is a thermal conductivity detector fabricated on a silicon nitride window by MEMS technology. A normal Wheatstone bridge is used. The signal is fed into a PC and displayed through LabView software.
Design, Fabrication and Optical Characterization of Micro Fresnel Zone Plates
Authors: Lee Wen-Hong , Lin Liwei 
Published: February 2022

Abstract
Design, fabrication and optical characterization of micro Fresnel Zone Plates (FZP) are successfully demonstrated. These micro FZPs are composed of circular rings that have a maximum size of 9.4 mm in diameter and a minimum ring width of 2 μm. The absorber material is sputtered tungsten with a thickness of 0.5 μm that is deposited on top of a 2.5 μm thick low-stress nitride membrane. An optical system that is composed of a He-Ne laser, a pin-hole, various lenses and a CCD camera, is setup to measure the optical characteristics of micro FZPs. It is found that the relative intensity can be magnified about 100% higher by using these FZPs. These FZPs are powerful tools for forming images in the spectral region of infrared light, X- and gamma-rays where regular glass lenses can not be functional.
An 8x8 Robust Capacitive Pressure Sensor Array
Authors: Chang Sung-Pil , Lee Jeong-Bong , Allen Mark G. 
Published: February 2022

Abstract
In this work, robust substrates, such as stainless steel, have been studied as substrates for micromachined devices. The use of robust substrates may allow for the co-fabrication of micromachined devices and sensor packages. Lamination process techniques combined with traditional micromachining processes have been investigated as suitable fabrication technologies. To illustrate these principles, a capacitive pressure sensor array has been designed, fabricated, and characterized using a stainless steel substrate, Kapton polyimide film as a suspended movable plate, and an electroplated nickel fixed back electrode. The net capacitance change of this sensor over the applied pressure range (0 to 34 kPa) was approximately 0.14 pF. Multivibrator circuitry has been integrated with pressure sensors in a hybrid fashion and used for frequency-modulated output measurements. An important attribute of this design is that only the steel substrate and the pressure sensor inlet is exposed to the flow; i.e., the sensor is self-packaged.
MemCel: An Inexpensive and Efficient Tool for 3D MEMS Prototyping
Authors: Emmenegger Markus , Korvink Jan G. , Baltes Henry 
Published: February 2022

Abstract
We present a fast prototyping tool for the 3D visualisation and subsequent finite element simulation of 3D CMOS micro-electro-mechanical systems (MEMS). Our process emulation method takes as input the 2D mask layout in CIF format, together with the corresponding process description, and generates a cell representation of the 3D device. The cell representation correctly reflects the layer structure of the device in the direction perpendicular to the wafer surface. Our emulation tool MemCel currently runs in the Mathematica environment, enabling the efficient conversion of 2D design data to 3D representation good for visualisation and simulation. We illustrate the technique for typical surface micromachined and interconnect devices.
MEMS Opportunities in the Automotive Industry
Authors: Sickafus Ed 
Published: February 2022

Abstract
For nearly two decades the automobile industry has watched the MEMS area in anticipation of exciting new products with greater functionality and higher reliability. Considering the long development time that has ensued, it is a bit of a disappointment to see the limited adaptation of MEMS devices in automobiles to date. Examination of this situation points up some of the difficulties of meeting the needs of the industry for automotive sensors and actuators. A distinction that needs to be made to understand the problem is the distinction between MEMS potential for automotive applications and actual adaptation of MEMS. The potential for MEMS automotive applications will be examined first, then the actual successes will be discussed. Lastly, reasons for the limited successes of automotive-type MEMS will be examined. This will bring out some needs for new direction as well as needs to understand business decisions and MEMS comptetition.
Operationally Focused Management of Pumps in Alert: Using Analysis to Remove a High Pressure Safety Injection Pump From Increased-Frequency Test Schedule
Authors: Arnold Eli 
Published: February 2022

Abstract
Pressurized water reactor designs preclude full-flow testing of certain safety-related standby pumps during power operations. This is problematic for Group B pumps that test in the alert range under comprehensive pump test conditions that are only available during refueling outages. The ASME OM committees sought to resolve this issue when new provisions were added to ISTB-6200 in ASME OM-2012. The provisions allow analysis of pump performance in lieu of testing at an increased frequency. Palo Verde Generating Station employed these rules to satisfy OM requirements for a vibration alert range entry of its high pressure safety injection pump without having to submit for regulatory relief or shut down to perform the test. The changes to ISTB-6200 in ASME OM-2012 give plants the flexibility to ensure safe operation without undergoing extraordinary measures to accommodate testing requirements.
Augmented IST Program Requirements – Scope and Testing
Authors: Gowin Mark 
Published: February 2022

Abstract
The purpose of this presentation is to raise awareness on the requirements in 10 CFR 50.55a(f) (4) for development and implementation of an Augmented IST Program. This presentation will highlight the changes in 10 CFR 50.55a rulemaking that changed the scope of the regulatory required IST Program to include all safety related components regardless of their site specific ASME Code Class equivalent classification. This presentation will also describe the available options to address those components classified as ASME Code Class 1, 2, or 3 equivalent versus those that are not classified as ASME code equivalent which also meet the scope statement of ASME OM Code, ISTA-1100.