bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Cooling Enhancements in a Heated Channel Using Flow-Induced Motion
Authors: Verma Mayank , De Ashoke
Published: November 2021

The paper presents the comparative study of the vortex-induced cooling of a heated channel for the four different cross-sections of the rigid cylinder, i.e., circular, square, semi-circular, and triangular, with or without the rigid/flexible splitter plate at the Reynolds number (based on the hydraulic diameter) of 200. The study presents a comprehensive analysis of the flow and thermal performance for all the cases. For flexible plate cases, a partitioned approach is invoked to solve the coupled fluid-structure-convection problem. The simulations show the reduction in the thermal boundary layer thickness at the locations of the vortices resulting in the improved Nusselt number. Furthermore, the thin plate's flow-induced motion significantly increases the vorticity field inside the channel, resulting in improved mixing and cooling. It is observed that the plate-motion amplitude is maximum when the plate is attached to the cylinder with the triangular cross-section. The power requirement analysis shows that the flexible plate reduces the power required to pump the channel's cold fluid. Thus, based on the observations of the present study, the authors recommend using the flexible plate attached to the cylinder for improved convective cooling.
A Heritage Approach to Risk Based Design
Authors: Fragola Joseph R.
Published: November 2021

Designers seldom, if ever, create designs “out of whole cloth”. They might begin with a clean piece of paper but their designs, no matter how creative or pioneering, must always embrace the technological heritage within which they are imbedded, at least to a degree. If they fail to do so they will almost certainly have great difficulty in being implemented, and even greater difficulty being successful. In this way the words “heritage” and “risk” have been linked, since time immemorial, in the design process and therefore in the designer’s mind’s eye. While this linkage is, in this sense, nothing new, the linkage has until recently been done heuristically and informally based upon the judgment and expertise of the individual designer, perhaps supplemented by the judgment and expertise of those peers of personal acquaintance.

Recently, as an outgrowth of the broader application of probabilistic technology, a more formal and systematic link between design heritage and design risk has been attempted. While the number of actual applications are few, those that have been attempted seem to forecast that significant benefits might accrue from further development of the concept and its wider application especially in the case of the advanced technical designs so characteristic of aerospace systems. While the process of risk-based design is still in development, the individual steps in the process are beginning to evolve.

These steps, which are listed in summary form in Figure 1 below, will be discussed in the presented paper as they apply to the design of a container to return samples from Mars.
Partitioning System Architecture to Optimize Reliability While Limiting the Impact of Cost, Weight and Schedule
Authors: Wasiloff James M. , Regan Robert J.
Published: November 2021

A method using discrete design optimization to maximize product reliability and customer satisfaction through uniquely partitioning system architecture is developed and presented in this paper. Using integer programming, constraints such as cost, weight and physical volume are incorporated into a mathematical model to improve system reliability through the introduction of system architectural redundancies. An advanced automatic transmission electronic shift control system is examined as a potential application for the aforementioned methodology. A significant improvement in system reliability is achieved through the application of this optimization tool in the shift control design problem. A generic model is proposed for architectural optimization of emerging advanced technology systems with requisite critical reliability requirements.
Design of Hydraulic Motor Spindle for High Speed Machining
Authors: Agba Emmanuel I. , Babai Majid
Published: November 2021

This paper presents the design of a hydraulic motor driven spindle for the processing of metals and composite materials at high rotational speeds. Existing technologies applicable to spindles and spindle holders under severe operating conditions were reviewed. A conceptual design of the hydraulic spindle system was developed. A strong indication of distinct increase in spindle life and gains in cutting power at higher rotational speeds when compared to the conventional electric motor driven spindles underscored the need for the new spindle system.
Design the Angular Feature for Manufacturability With Tolerance Chart
Authors: Xue Jianbin , Ji Ping
Published: November 2021

Many products have angular features for certain special functions. Although the design engineers have considered the capability of manufacturing process when they design the parts of a product, some hidden problems about the manufacturability of the angular features are still difficult to be discovered by most of the design engineers. In this paper tolerance charts are used to design the angular features for manufacturability. Using the tolerance chart for a simple tapered part, the work dimensions and tolerances at each operation stage of manufacturing are obtained. A very tight tolerance on adjacent surfaces is created because of the tapered feature. This problem will not be discovered until the tolerance chart is employed to analyze the designed tolerances and the operation sequence. Therefore, either the design of the tolerance or the process plan of the workpiece should be modified in order to fabricate the part at a small cost of manufacturing.
Interoperability, Shape Representation, and Geometric Processing for Network-Enabled Virtual Prototyping
Authors: Lee Jae Yeol , Lee Joo-Haeng , Kim Hyun , Han Sung-Bae
Published: November 2021

Internet technology opens up another domain for building future CAD/CAM environment. The environment will be global, network-centric, and spatially distributed. In this paper, we present a new approach to network-centric virtual prototyping (NetVP) in a distributed design environment. The presented approach combines the current virtual assembly modeling and analysis technique with distributed computing and communication technology for supporting virtual prototyping activities over the network. This paper focuses on interoperability, shape representation, and geometric processing for distributed virtual prototyping. STEP standard and CORBA-based interfaces allow the bi-directional communication between the CAD model and virtual prototyping model, which makes it possible to solve the problems of interoperability, heterogeneity of platforms, and data sharing. STEP AP203 is utilized as a means of transferring and sharing product models. In addition, Attributed Abstracted B-rep (AAB) is introduced as 3D shape abstraction for transparent and efficient transmission of 3D models and for the maintenance of naming consistency between CAD models and virtual prototyping models over the network. Further, this paper discusses geometric processings needed for distributed virtual prototyping activities such as collision detection and interactive assembly modeling.
Electrostatic Latch and Release: A Theoretical and Empirical Study
Authors: O’Brien Gary J. , Monk David J. , Lin Liwei
Published: November 2021

Two new theoretical electrostatic actuator models describing MEMS cantilever beam deflection are presented. The 1st proposed model uses beam theory to predict electrostatic pull-in to occur at a beam tip displacement of 46% the initial actuator gap. The proposed beam theory model is comprised of a cantilever with an applied moment at the free end to represent the electrostatic force across the beam. The 2nd proposed model describes cantilever beam electrostatic pull-in occurring where the cantilever beam tip deflection represents 44% of the initial actuator gap as a function of the cantilever beam deflection angle. System non-linearity is addressed using a more accurate electrical capacitance model near the deflected cantilever beam tip where electrostatic forces are maximized. Empirical pull-in voltage measurements of polysilicon cantilever beam arrays correlate to both presented models with better performance than previously presented theoretical models without the use of correction factors. Extension of the 2nd model to describe a class of torsional electrostatic actuators is also demonstrated. Electric field fringing is neglected regarding capacitance model calculations.
Out-of-Plane Comb-Drive Lever Actuator
Authors: Lin Hung-Yi , Fang Weileun
Published: November 2021

In the present study, an out-of-plane motion actuator driven by the electrostatic force is designed and fabricated. The electrostatic force generated by the gap closing electrodes and the comb electrodes will be studied. Moreover, a lever motion transmitting mechanism is proposed to modulate the motion of the actuators. Although the space between the driving electrodes is limited, the lever motion transmitting mechanism could enlarge the traveling distance. The applications of the out-of-plane motion actuator are remarkably increased due to the assistant of the transmitting mechanism.
Down-Scale Problems of Resonant Mode SiC Devices
Authors: Kazinczi R. , Mollinger J. R. , Bossche A.
Published: November 2021

Silicon carbide (SiC) is a promising candidate to replace conventional silicon based electronics and micro electromechanical devices in various applications. The present study characterizes material properties of SiC thin films and addresses reliability issues focused on down-scaled resonant mode future devices. The Young’s modulus was calculated from resonant measurements on SiC cantilever beams. The long-term stability of the resonator was studied in various environments. Thin cantilevers operating in air and in humid air exhibit stiffening effect due to surface oxidation. Mechanical shocks generate cracks in the surface oxide layer which results in drop of the resonance frequency. This unstable behaviour leads to failure of the resonant mode devices. Non-oxidising media, such as nitrogen and argon enhances the stability, which offers convenient packaging solutions.
Analysis and Design of Electrothermal Actuators Fabricated From Single Crystal Silicon
Authors: Maloney John M. , DeVoe Don L. , Schreiber David S.
Published: November 2021

Thermal actuators that deflect laterally by resistive heating have been fabricated in single crystal silicon (SCS) by deep reactive ion etching (DRIE). With heights of 50 μm, these high-aspect actuators produce significantly larger forces than similar polysilicon devices. Problems with stiction are also avoided through the use of silicon-on-insulator (SOI) technology. An analytical model is applied to U-beam and V-beam actuator shapes fabricated on SOI wafers. The electrothermal component of the analysis uses an axial conduction model to predict temperature distribution; the thermomechanical component employs elastic beam theory to calculate deflection due to thermal strain. Experimental results are compared to analytical predictions. Deflections of 29 μm for a 1200 μm long, 12 μm wide V-beam actuator were observed, corresponding to a predicted force of 7.6 mN.
A Microactuator for a High-Density Hard Disk Drive
Authors: Cho Dong-Woo , Kim Jong-Young , Lee Sang-Jo , Park Ji-Whang , Choi Seok-Moon , Ahn Seung-Do
Published: November 2021

This paper reports the design and fabrication of a micro-electro-mechanical-system (MEMS)-based electrostatic angular microactuator for a dual-stage servo. We propose a new driving scheme that uses the vector sum of the force generated by parallel plate and comb-finger. To maximize the driving moment, the moving and fixed electrodes are arranged to make the driving force perpendicular to the rotating moment of arm. We designed a 2-mm diameter microactuator that can position the pico-slider over ± 1 μm stroke using under 18 volts with a 1 kHz flexural natural frequency for a 2 kHz fine-tracking servo.
MEMS Flip-Up Micro-Coil Inductors
Authors: O’Brien Gary , Monk David J. , Lin Liwei
Published: November 2021

Surface micromachined micro-coils rotated 180° out of the wafer substrate plane have been demonstrated using a hinged support frame structure. A slotted mechanical latch was used to maintain the flip-up (assembled) configuration of the micro-coil support frame. Assembled micro-coils were evaluated regarding potential use as integrated circuit inductors and micro-heaters. Inductance measurements were performed before and after micro-coil assembly. The single polysilicon layer micro-coil inductance was measured as 0.95nH and 4.60nH, pre and post assembled respectively. This represents a 480% improvement as compared to a planar micro-coil implementation. The single polysilicon layer micro-coil is comprised of 4 turns with inner and outer spiral diameters of 40 and 100 microns respectively. Micro-coil support frames were assembled (latched) manually using probe needles. A batch assembly attempt using compressed gas bursts to flip-up the structures resulted in a quasi-latched state of the micro-coil support frame.
Non-Destructive, Non-Contact Handling and Concentration of μm-Sized Particles in Liquid Using Superposition Method of Ultrasound
Authors: Yasuda Kenji
Published: November 2021

The non-destractive, non-contact concentrating method using ultrasound for biological analysis was studied. Using the superposition method, which is a kind of fourier synthesis of higher harmonics of ultrasounds, we can arrange the desired shape of acoustic potential well and can concentrate biomaterials effectively without any contact, and damage. We also applied the superposition method for continuous concentration and found the method improved the concentration efficiency substantially.
HDD Tracking Microactuator and Its Integration Issues
Authors: Hirano Toshiki , Fan Long-Sheng , Kercher Dan , Pattanaik Surya , Pan Tzong-Shii
Published: November 2021

Integration issues of a micro-actuator for HDD tracking servo were investigated, and many innovative technologies were developed. In order to electrically connect magnetic head to the external electronics, we devised “integrated flexible wire” structure, which is a micro-fabricated flexible electrical wire. Connection between micro-actuator’s bonding pad to the suspension was realized by an “inter-connect module,” which is a micro-fabricated miniature flexible printed circuit. Connection between components was done by “solder bumper” process, a precise solder ball placement/laser-reflow technology. The size of a micro-actuator must be small enough so that it has minimum impact on the dynamics and packaging density. We have designed extremely area-efficient micro-actuator, which can produce large force by small device area. The thickness of micro-actuator was also reduced to 160 μm by backside grinding of silicon substrate.
A Novel Bleached Fluorescence Imaging Technique for Microfluidics
Authors: Mosier Bruce P. , Mikkelsen James C. , Santiago Juan G.
Published: November 2021

A bleached fluorescence imaging technique for visualizing microscale flow fields and obtaining scalar diffusion and convection information has been developed. In order to make the technique quantitative, experiments have been conducted to measure the electrophoretic mobilities of fluorescein and fluorescein-dextran conjugates as well as the diffusion coefficients of a fluorescein-dextran conjugate. The technique offers the ability to track undisturbed fluorophores and to use fluorescent conjugates already present in the system. Typical polymer and glass microfluidic substrates will not significantly attenuate the laser light illumination as only visible light wavelengths are required. Applications of the technique to electroosmotically and pressure-driven flows are presented.
Development of a Planar Electrokinetic Micropump
Authors: Chen Chuan-Hua , Zeng Shulin , Mikkelsen James C. , Santiago Juan G.
Published: November 2021

Electrokinetic (EK) micropumps use electroosmotic flow to produce high pressures in a compact design with no moving parts. An EK micropump has been fabricated on a 50 × 75 × 1.2 mm soda-lime glass substrate using standard microlithography and chemical wet etching techniques. The pump is 1 mm long in the flow direction and 0.9 μm × 38 mm in cross section. A preliminary model has been developed to characterize the flow rate, pressure capacity and thermodynamic efficiency of the pump. Experiments have been conducted using deionized (DI) water (pH = 5.6, conductivity = 1 × 10−3 S/m) as working fluid. Experimental data show a linear relationship between flow rate and counter pressure, which agrees well with the pump model. The data also show a nonlinear increase of flow rate with increasing applied voltage, which indicates temperate rise of the working fluid due to Joule heating. The flow rate of the pump at 1 kV degrades from 15 μl/min to 0.2 μl/min over a period of two months, while the pressure capacity remains around 0.3 atm and current of pump circuit remains around 2 μA. This long-term degradation, although still under investigation, is probably due to a collapse and bonding of the glass in the region of the thin (0.9 μm) pump channel.
Fluidic Capacitance Model of Capillary-Driven Stop Valves
Authors: Zeng Jun , Deshpande Manish , Greiner Ken B. , Gilbert John R.
Published: November 2021

This paper presents current research in design analysis of passive micro-fluidic stop valves driven by capillary forces. Capillary valves are used in controlling the liquid position by presenting a capillary pressure barrier due to a sudden change in cross-section. Valves of this type have multiple advantages on precise control in micro-fluidic devices over conventional ones.

In the design of a device employing such valves, a model describing the behavior of these valves is highly desirable. In this paper, we describe the extraction of this model using numerical techniques validated with experiment. The numerical analyses are conducted in FlumeCAD, a design and analysis tool for micro-fluidic devices. The detailed analyses yield a fluidic capacitance model for the capillary-driven valves. Devices that are pneumatically pressurized and driven by centrifugal force are studied in this paper. The methodology presented in this article can, in principle, be applied to a wide range of devices and actuation mechanisms.
A Quality Study on the Excimer Laser Micromachining of Electro-Thermal-Compliant Micro Devices
Authors: Li Jun , Ananthasuresh G. K.
Published: November 2021

The objective of this research is to improve the quality of the KrF excimer laser micromachining of metal and silicon in fabricating Electro-Thermal-Compliant (ETC) micro devices. The ETC devices combine the actuator and the mechanism into one monolithic compliant continuum and enable a range of mechanical manipulation tasks at micron scale. An efficient method to optimize the process parameters in laser micromachining using the orthogonal array-based experimental design method is presented in this paper. The feed rate of the XY stage, the laser pulse frequency, the discharge voltage and the number of passes were used as the control parameters. The roughness of the machined edge was used as the primary indicator of cutting performance. The roughness of the edges was computed automatically from the optical image of the machined samples. The orthogonal array method enabled the optimization of the control parameters by reducing the required number of experiments compared to the traditional full factorial experiment. Furthermore, machining in a liquid environment improved the quality and eliminated more debris and recast compared to machining in the air.
The Breath of Collaboration of Academia, Industry, and Governmental Sectors in Japan
Authors: Katsuta Masafumi
Published: November 2021

The research environment of science and technology is going to change rapidly (dramatically) with the change of Japanese society change at the turn of the century. In this article, a discussion on what kind of academic policy put into the effect aiming to enhance collaborative research in Japanese universities and to foster interdisciplinary research between separate established organizations is attempted. A typical example of a successful system, The Advanced Research Institute of Science and Engineering at Waseda University, will be described.
Eight Strategies for Mass Customization
Authors: Baudin Michel
Published: November 2021

How can we satisfy every customer whim at prices that are no higher than those of competitors who offer only a few products? The following strategies have worked in many circumstances:

1. Analyze the structure of the demand. We need to be able to make what customers do order, not everything they might.

2. Standardize components. Custom products do not always have to be made from scratch. Instead, they can be made from a small number of standard components.

3. Make a catalog with a discrete set of sizes. All shoes used to be custom-made, but today, shoes made in size increments meet the needs of almost all consumers.

4. Postpone customization to the end of the process. Customization happens best at or near the end of the manufacturing process.

5. Identify a common process. Then we can treat custom products like options on standard products.

6. Maintain a database of past designs. It can be an enormous time saver in meeting requirements that appear to be new.

7. Design your custom manufacturing process. While still as a job-shop, the custom workshop must be organized for effectiveness and efficiency.

8. Set up a simple production control system. Cap the number of jobs in process, sequence WIP FIFO, do all priority shuffling prior to job release, and track progress with Ybry charts.
Florida’s Strategy for the Management of End-of-Life Computers, CRTs and Other Electronic Equipment
Authors: Clark Raoul
Published: November 2021

Recent estimates suggest that 160,000 computers will be discarded into Florida landfills in 1999, and that by 2005, this number could increase to 420,000 computers landfilled. Similarly, televisions discarded in Florida landfills may increase from 1,040,000 in 1999 to 1,200,000 in 2005. The cathode ray tubes (CRTs) in this equipment pose a major health concern, because of their lead content. Obviously, a well-planned strategy is required for managing discarded CRTs.

The strategy proposed here includes (1) specifying the regulatory framework to allow CRTs to exit the hazardous waste stream in certain cases; (2) promoting the recycling infrastructure by reimbursing some costs with state funds; (3) evaluating collection strategies and other management options through pilot programs; and (4) developing a state electronics recycling contract, possibly like the state fluorescent lamp recycling contract.
Multiaxial Behavior and Viscoelastic Constitutive Modeling of Epoxy Polymers
Authors: Ellyin F. , Hu Y. , Xia Z.
Published: November 2021

A nonlinear viscoelastic constitutive model previously proposed has been modified to account for hydrostatic stress influence. The modification is achieved by incorporating the hydrostatic stress in the equivalent stress definition. The present model predicts a shift of stress envelopes along equibiaxial compressive stress direction. It also predicts different octahedral shear stress versus octahedral shear strain curves for various strain paths. These trends indicate improved agreement between the model prediction and multiaxial experiment data.
Ride Comfort of Five-Axle Tractor/Semi-Trailer
Authors: Jiang Zhenyu , El-Gindy Moustafa , Streit Donald
Published: November 2021

The issue of ride comfort for vehicle operations has recently generated considerable interest especially in heavy vehicle systems since long-distance drivers are more likely to experience high levels of vibration. This paper introduces the general concept of vibration-related health problems, discusses ride comfort assessment criteria and methods, and then focuses on the methodology of using computer simulation to analyze ride comfort. The computer-based ride comfort model can be divided into three sub-models: vehicle model, driver/seat model, and road profile input model. Several vehicle models and driver/seat models are reviewed and detailed modeling techniques are introduced.

A five-axle tractor/semi-trailer/driver combination ride comfort simulation model is developed in this paper using the software DADS. Both four-spring tandem suspension and independent air spring suspension are studied. Road profiles are assumed as static zero mean Gaussian random process. Vertical acceleration at the interface between seat and driver body is obtained from simulation results. Power spectral density and root mean square (RMS) vertical acceleration are calculated based on simulation results. RMS acceleration at ISO classified good and average roads are compared with ISO 8-hour fatigue vibration limit. It is found that RMS acceleration of this particular vehicle simulated in this paper is below the ISO 8-hour fatigue limit for both good and average roads when traveling at the speed of fifty miles per hour. This implies a good ride comfort. Axle dynamic load coefficients (DLC) are calculated for four suspension configurations that are combinations of air springs and steel springs. Results show that large DLC doesn’t necessarily indicate bad ride quality.
On the Integrated Design of the Tyre-Suspension System of a Racing Car
Authors: Miano Carlo M. , Gobbi Massimiliano , Mastinu Giampiero , Cesarini Riccardo
Published: November 2021

The paper presents a procedure for the integrated design (tuning) of tyres and suspensions of racing cars.

A complete model of a racing car has been developed and implemented. The model is suitable to simulate the vehicle behaviour in extreme driving conditions.

A number of ground tests have been performed to validate the vehicle model, with fully satisfactory results.

Many different driving situations (steady state, J-turn, lane-change, power-on/off while steering, braking on a bend, passing over a kerb while steering) have been considered. By means of a Multi-criteria approach many performance indexes have been optimised by changing the parameters related both to the vehicle suspension system and to the tyre characteristics. A global-approximation model has been built (the original physical model has been substituted by another purely numerical model), allowing fast optimisations. A number of preferred solutions have been selected from the optimal set. Professional drivers tested the cars fitted with optimal suspension/tyre settings. The improvements predicted by computations were substantially confirmed. The adopted procedure has proved to be reliable and effective both for obtaining the highest performances and for reducing the number of ground tests.
Analysis of Sink Marks for Plastic Parts Molded in Steel and Aluminum Alloy Molds
Authors: Iyer Natraj , Ramani Karthik
Published: November 2021

Recently developed aluminum alloys show significant potential as injection mold materials for their ability to cool plastic parts faster than steel. These alloys maintain more uniform mold temperatures that can have significant effects in reducing post-molding shrinkage. Commercially available software can be used to predict the global shrinkage in a part. However, none of the currently available software predicts localized sink mark formation. In the present work, temperature and pressure histories from a three-dimensional molding analysis using C-Mold™ are used to determine the initial conditions for a sequentially coupled thermal and structural finite element analysis using ANSYS™. The thermal conductivity, density and specific heat of the polymer are input as temperature dependent properties. The polymer is modeled as a temperature dependent elastic material.

Correlations made between numerical and experimental data for sink mark depths in parts molded in P-20 steel and QE-7™ aluminum alloy molds validate the use of the sink mark simulation method. Numerical comparison of sink mark depths for parts molded in aluminum alloy and steel molds show that aluminum alloys reduce sink mark depths in molded parts.
Gate Location Optimization in Injection Molding Processing
Authors: Lin Baojiu , Ryim Won Gil
Published: November 2021

Improvements in part quality and cost reduction are the primary objectives of CAE use in the injection molding industry. Engineers use advanced injection molding simulation software to analyze and verify their part designs. Traditionally, engineers have had to rerun simulations to verify the effects of changes in gate locations. For complex models, simulations are very time consuming. To reduce the design cycle time, a Design Optimization Module is developed by C-MOLD. One of the functions of this new software module is to automatically select optimal gate locations. This innovative technology is the result of close R&D collaboration between C-MOLD and LG-PRC in Korea. An overview of gate location optimization technology is presented in this paper, and several examples are also presented as illustration.
The Effect of Aging on the Microstructure and Precipitation Response of an Aluminum-Lithium Alloy
Authors: Fragomeni James M.
Published: November 2021

The consequence of thermal treatment on the precipitation response of intermetallic precipitates in the microstructure microstructure and subsequent mechanical properties of an Al-2.6wt.%Li-0.09wt.%Zr alloy was studied. The alloy was solution heat treated and artificially aged for a series of aging times and temperatures at various precipitation hardening conditions. The underaged, peak-aged and overaged microstructures of the alloy were analyzed. Quantitative particle size measurements were performed to determine the size, distribution, morphology and coarsening rate for both δ′(Al3Li) and δ′(Al3Li)/Al3Zr precipitates. The average particle size, distribution, spacing and volume fraction of the intermetallic precipitates were related to the heat treating process. For all of the aging times studied, the δ′(Al3Li)/Al3Zr particles were much larger in size than the δ′(Al3Li) and Al3Zr-free particles. The particle coarsening rate, determined from the Lifshitz, Slyozov and Wagner coarsening rate theory, was more accelerated for the δ′(Al3Li)/Al3Zr particles than for the δ′(Al3Li) precipitates. The presence of the Al3Zr phase was found to accelerate the aging kinetics of the alloy. Therefore, a small amount of zirconium in the alloy resulted in a faster particle coarsening rate of the overall combined particle size distribution and thus led to more rapid precipitation aging response.
The Contour Method: Simple 2-D Mapping of Residual Stresses
Authors: Prime Michael B.
Published: November 2021

An entirely new method for measuring residual stress that is extremely simple to apply yet more powerful than existing techniques is presented. In this method, a part is carefully cut in two. The contour of the resulting new surface is measured, which gives the displacements caused by the release of the residual stresses. By Bueckner’s superposition principle, analytically forcing the surface back to its original flat state gives the residual stresses that originally existed normal to the plane of the cut. The main advantage of this method is that the measured data can be used to solve directly for the stresses, whereas other methods require a complex inversion process.
The Approximate, High Frequency Response of a Panel With Attached Masses
Authors: Reynolds Robert R.
Published: November 2021

The high frequency response of a panel with attached masses is approximated using transient, asymptotic modal analysis (AMA). These relations are derived by applying asymptotic simplifications to classical solutions in both the time and frequency domains. The geometry consists of several masses that are attached to a panel to which impulsive excitations are applied. Predictions are made of the mean-squared, transverse displacement history and the localized responses near the added masses. These are compared to classical solutions and it is shown that for a few masses that are separated by more than a mean wavelength, the panel behavior can be estimated well by the AMA expressions. The approximate solutions are shown to require less than 20% of the computational time and memory of the classical solutions and are applicable to general forms of excitation.

The resulting capability can be used to estimate acoustic emissions from vibrating equipment and to model structure-borne sound and its effects on sensitive equipment.
Experimental Study of Heat Transfer Properties of Policapillary Materials
Authors: Veksler Eugene M. , Tuchinsky Lev J. , Loutfy Raouf O.
Published: November 2021

Experimental study has been carried out to investigate convective heat transfer properties of air-cooled multi-channel tubes, fabricated using polycapillary materials technology, subjected to external heating. Practically important expressions for Nusselt number and hydraulic resistance coefficient were obtained for Re = 200–5000 and compared with existing correlations.
A Numerical Study of Turbulent Boundary Layer Flow Over a Flat Surface With a Single Dimple
Authors: Kithcart Mark E. , Klett David E.
Published: November 2021

Turbulent boundary layer flow over a flat surface with a single dimple has been investigated numerically using the FLUENT CFD software package, and compared to an experiment by Ezerskii and Shekhov [1989], which studied the same configuration. The impetus for this work developed as a result of previous studies. Kithcart and Klett [1996], and Afanas’yev and Chudnovskiy [1992], showed that dimpled surfaces enhance heat transfer comparably to surfaces with protrusion roughness elements, but with a much lower drag penalty. However, the actual physical mechanisms involved in this phenomena were only partially known prior this study. Results obtained numerically are in good agreement with the experiment, most notably the confirmation of the existence of a region of enhanced heat transfer created by interaction of the flow with the dimple. In particular, the simulation indicates that heat transfer augmentation is a consequence of the development of a stagnation flow region within the dimple geometry, and the existence of coherent vortical structures which create a periodic flow-field within and immediately downstream of the dimple. This periodicity appears to govern the magnitude of the heat transfer augmentation.
The Use of Decomposition for the Large Scale Synthesis/Design Optimization of Highly Coupled, Highly Dynamic Energy Systems: Part II—Applications
Authors: Muñoz Jules R. , von Spakovsky Michael R.
Published: November 2021

An application of the Iterative Local-Global Optimization (ILGO) decomposition approach developed in an accompanying paper (Muñoz and von Spakovsky, 2000b) is presented. The synthesis / design optimization of a turbofan engine coupled to an environmental control system for a military aircraft was carried out. The problem was solved for a given mission (i.e. the load / environmental profile) composed of fifteen segments. The number of decision (independent) variables used for this highly non-linear optimization problem is one hundred fifty-three, some of which are integer. Both thermodynamic and physical (weight and volume) simulations use state-of-the art tools. Two objective functions were investigated: take-off gross weight and mission fuel consumption, and no observable differences were found in the final results. In addition to the mathematical foundations for global convergence of the proposed decomposition approach presented in Muñoz and von Spakovsky (2000b), numerical support for this convergence was found by solving the entire mixed-integer non-linear programming (MINLP) problem without decomposition using a subset of the independent variables. The constant value of the marginal costs (or linear behavior of the Optimum Response Surface — OSR) played a major role in the global convergence of the ILGO.
Analysis and Test of a Proton Exchange Membrane Fuel Cell Oxidant System
Authors: Vasquez Arturo , Varanauski Donald E. , Clark Robert W.
Published: November 2021

An effort is underway to develop a Proton Exchange Membrane (PEM) Fuel Cell system for future space applications. A breadboard system has been constructed and includes the following: reactant pressure regulators, ejector-based reactant pumps, a 4-kW fuel cell stack, and a passive, membrane-based oxygen / water separator. A computer model is being developed concurrently to analytically predict fluid flow in the oxidant reactant system. Preliminary data obtained from tests performed with the breadboard system, as well as other published data, has been used to validate the analytical component models. These components have been incorporated into an integrated oxidant fluid system model. Results obtained from both the performance tests and the analytical model are presented.
Hydrodynamics and Thermodynamics of Newtonian Stars
Authors: Kwak Ho-Young , Jun Jung-Hwan
Published: November 2021

We investigated spherically symmetric solution for nonrelativistic cosmological fluid equations and thermodynamic equation of state for Newtonian stars. It was shown that the assumption of a polytropic state equation, P 0 = κ ρ 0 γ , at the center of the star only suffices to integrate the equations explicitly. Our exact solution yields many fruitful results such as stellar stability, spherical oscillation and collapses of stars. Pressure, temperature, and density profiles inside stars were obtained. Central densities, pressures and temperatures of the Newtonian stars such as Sun, Jupiter and Saturn were also calculated. Analytical results show that stars with γ ≤ 4/3 are unstable so that they are collapsing or they may expand forever. On the other hand, stars with γ > 4/3 are stables so that they could undergo spherical oscillation. The upper bound value of white dwarf mass obtained turns out to be close to the Chandrasekhar limit. Motion of the Universe was also discussed within the framework of Newtonian mechanics.
Exergy Analysis of Integration Between Air Separation Process and IGCC
Authors: Liu Zelong , Jin Hongguang , Lin Rumou
Published: November 2021

Integrated Gasification Combined Cycle (IGCC) is considered as one of the advanced clean coal power technologies. Here, we have investigated an IGCC with air separation unit (ASU) on the basis of exergy analysis, and clarified the distribution of exergy destruction in sub-systems including air separation unit, coal gasifier, coal gas clean-up unit, air compressor, combustor of gas turbine, gas turbine, heat recovery steam generation and steam turbine. Particularly, we have focused on the interaction between the ASU and the gas turbine (GT). The results obtained disclosed the significant role of the integration between air separation unit and air compressor in the GT, and the effect of nitrogen injection to the combustor on IGCC overall performance. The study also points out that larger exergy destruction take place in the processes of gasification, combustion in GT, and air separation, and so does the change of exergy destruction distribution with the air integration degree and the nitrogen injection ratio. We have demonstrated the potential for improving the IGCC system. This investigation will be valuable for the synthesis of next-generation IGCC.
Evaporative Gas Turbine Cycle: A Description of a Pilot Plant and Operating Experience
Authors: Lindquist Torbjörn O. , Rosén Per M. , Torisson Tord
Published: November 2021

In recent years the interest for new advanced thermodynamical gas turbine cycles has increased. One of the new designs is the evaporative gas turbine cycle. A lot of effort worldwide has been put into predicting the possible efficiency, pollutants, and dynamic behaviour of the evaporative gas turbine cycle, but all results so far have been affected by uncertain assumptions. Until now this cycle has not been demonstrated in a pilot plant. The purpose of this work has been to identify the potential of this cycle, by erecting a pilot plant at the Lund Institute of Technology. The project was financed on a 50/50 basis from the Swedish National Energy Administration and the industrial partners.

Three different thermodynamical cycles have been tested in the pilot plant: the simple, the recuperative, and the evaporative cycle. The final pilot plant roughly consists of a 600 kW gas turbine, a hydraulic brake, a recuperator, a humidification tower, an economiser, and a flue gas condenser. All layout and functional analysis were made within the project. The pilot plant is, however, optimized neither for best efficiency nor for best emissions, due to the choice of standard components out of economical reasons. It has only been built for demonstration purpose.

Maximum simplicity, flexibility and safety have been the main emphasis in the design of the EvGT cycle. The flow mismatch that occurs between the compressor and the expander in evaporative cycles makes it hard to use a standard gas turbine unit. To be able to use a standard unit, an air bleed off system has been introduced. The water circuit can, at any time, be connected or disconnected from the humidification tower, thereby creating a possibility of controlling when humidification takes place or not by means of a water bypass past the humidification tower. Two starting sequences have been developed, one with the humidification process fully integrated from the beginning and one without. It has been shown that it is possible to reach full power output from the evaporative gas turbine cycle almost as fast as for the simple cycle. It has also been shown that the process is very stable when operated at various loads and during load transients. Furthermore, it is possible to start the power plant quickly from a remote place.
Computational Heat Transfer Analysis of a Furnace Using the WSGG Model
Authors: Omori Toshiaki , Yamaguchi Shunichi , Fusegi Toru
Published: November 2021

Accurate radiative heat transfer analysis is challenging due to the strongly spectral-dependent absorption coefficient and the requirement for satisfying both the summation and reciprocity laws in thermodynamics. In the paper, nongray radiation is treated by way of a computationally efficient Weighted Sum of Gray Gases (WSGG) model without much sacrificing prediction accuracy. In the present model, three gray gas components are used, one of which simulates the radiative window. The thermodynamic laws are simultaneously treated using a Monte Carlo method subject to a symmetrization procedure. As a test problem, radiative heat transfer in an industrial model furnace is solved to demonstrate effects of gray/nongray radiation and the grid size for CFD and radiation calculations.
Transient Radiative Transfer in Anisotropically Scattering Media Using Monotonicity-Preserving Schemes
Authors: Sakami M. , Mitra K. , Hsu P.-F.
Published: November 2021

This research work deals with the analysis of transient radiative transfer in one-dimensional scattering medium. The time-dependant discrete ordinates method was used with an upwind monotonic scheme: the piecewise parabolic scheme. This scheme was chosen over a total variation diminishing version of the Lax-Wendroff scheme. These schemes were originally developed to solve Eulerian advection problem in hydrodynamics. The capability of these schemes to handle sharp discontinuity in a propagating electromagnetic wave front was compared. The accuracy and the efficiency of the discrete ordinates method associated with the piecewise parabolic advection scheme were studied. Comparisons with Monte Carlo and integral formulation methods show the accuracy and the efficiency of this proposed method. Parametric study for optically thin and thick medium, different albedos and phase functions is then made in the unsteady state zone.
The pH Distribution During CO2 Dissolving Into Water Under Mid-Depth Sea Condition
Authors: Someya Satoshi , Nishio Masahiro , Chen Baixin , Okamoto Koji , Uchida Tsutomu
Published: November 2021

Sequestration of liquid CO2 into the intermediate depth ocean has been considered as a means to reduce atmospheric concentration of this greenhouse gas and mitigate global warming. A number of CO2 droplets are released and diluted into the intermediate ocean. The behavior of CO2 dissolution is very important in order to control the concentration of CO2 and to keep the environmental impact minimum.

Under conditions in the intermediate ocean, that is, high pressure and low temperature, the CO2 clathrate hydrate film was formed on the CO2 droplet surface. The hydrate film has been considered to decrease the dissolution rate and the CO2 concentration near the droplet surface.

The authors applied a LIF technique with a new kind of the dye as a pH indicator. The new dye in the CO2 dissolved water emitted intense fluorescence dependent on its pH. The visualized images showed the two dimensional distribution of the pH, i.e., CO2 concentration, around the CO2 droplet with or without the hydrate film.
A Mixed Environment for Effective Heat Transfer Learning
Authors: Braga Washington
Published: November 2021

This paper discusses aspects related to the undergraduate teaching of Heat Transfer in an environment using both Internet and classroom. The use of such an environment can be focused on the learning process of each student, using the classroom as formal check point for group work, sharing experiences and questioning, while the Internet is used for private follow-up, study and self evaluation. The paper describes the experience of one term using such an environment and several using Internet only as a tool for the learning process. The advantages already observed are reported, as well as the major difficulties still noticed. Internet is used continually throughout the course. Available material consists of quizzes, solved exercises, tutorials, spreadsheets, applets and others that the student may use through the Net or through a CD-Rom. Interaction between students and teacher is done mostly using an e-groups conference. Teamwork is strongly recommended, but challenging questions or exercises are expected to be solved exclusively on an individual basis. This paper supports the idea that the skill and attitude towards learning are most important to an effective life long learning.