bluuebunny/crossref_metadata_2025 huggingface dataset:
User Performance in a GUI Pointing Task With a Low-Cost Force-Feedback Computer Mouse
Authors: Hasser Christopher J. , Goldenberg Alex S. , Martin Kenneth M. , Rosenberg Louis B.
Published: January 2022

Force feedback has been shown to improve user performance in many teleoperation and virtual reality tasks. This paper investigates the ability of a force feedback computer mouse to improve performance in a graphical user interface (GUI) pointing task. Two studies are presented: a pilot study, and a second study with a more refined experimental design. Evaluation is performed using a Fitts’ Law paradigm. Results of the two studies show that the addition of force feedback can improve targeting performance by 61% and decrease targeting errors by 70% for the pointing task examined.
The Virtual Teacher
Authors: Gillespie R. Brent , O’Modhrain M. Sile , Tang Philip , Zaretzky David , Pham Cuong
Published: January 2022

This paper introduces the virtual teacher, a device or agent that supplements an environment in order to facilitate acquisition by a human user of a manual skill. Like the virtual fixture, a virtual teacher generally acts as an aide or facilitator to task execution, but unlike the virtual fixture, the virtual teacher is present only during training periods. During eventual task performance the teacher is absent. The virtual teacher’s objective, implicitly understood by the user, is to promote independent mastery over the task. We review and organize common paradigms for the teaching of manual skills in real-world settings and use these as inspiration for the design of virtual teachers. In particular, we are interested in the ways in which a teacher, real or virtual, can demonstrate a strategy or impart a ‘feel’ for a task by guiding movement of the pupil’s hand. A pilot study involving 24 participants was used to test the virtual teacher concept with a simulated crane moving task. The present virtual teacher implementation did not significantly improve learning curves. However, further performance interpretations indicate that the lack of positive effect can be remedied with modifications to the virtual teacher that address component skills and ensure suitability to various initial skill levels.
An Improved Method for Haptic Tracing of a Sculptured Surface
Authors: Johnson David E. , Cohen Elaine
Published: January 2022

We present an improved method for directly tracing a sculptured surface. This method extends previous work by adding second-order surface information to a closest point tracking algorithm which greatly increases the stability and also improves the accuracy of the algorithm. As part of the derivation of the new method, we examine in detail the system of equations that tracks the closest point on the surface and highlight surface features that can cause problems. We then address these potential problems.
FE Analysis of the Dynamic Characteristics of the Human Finger Pad in Contact With Objects With/Without Surface Roughness
Authors: Maeno Takashi , Kobayashi Kazumi
Published: January 2022

We calculate the transient dynamic response of human finger skin and the distribution of the strain energy density at the tactile receptors focusing on the effect of epidermal ridges on tactile sensation. Using a FE (finite element) model which we create from geometric and material properties measured from an actual human index finger, we introduce a method of dynamic contact analysis which we use to analyze the dynamic contact between a finger with/without epidermal ridges and an object with/without surface roughness. It is found that the epidermal ridges increase the sensitivity of the tactile receptors. The presence of epidermal ridges change either the distribution pattern or the amplitude of the strain energy density at the tactile receptors. It is also found that the Meissner’s corpuscles are relatively sensitive for detecting the surface roughness, whereas Merkel’s discs are relatively sensitive for detecting indentations in objects.
Education in Mechatronic Systems at the Ohio State University
Authors: Rizzoni G. , Keyhani A. , Washington G. , Chandrasekaran B. , Baumgartner G.
Published: January 2022

The aim of the present paper is to describe an ongoing curriculum development effort in Mechatronic Systems education at the Ohio State University, in collaboration among the departments of electrical and mechanical engineering, and of computer and information sciences. The paper presents the motivation for such a development, the history of mechatronics education at OSU, the current structure of the curriculum, and plans for future development.
The Effect of Grinding Machine Stiffness on Surface Integrity of Silicon Nitride
Authors: Yang Fulun , Zhang Bi , Wang Jiexin , Zhu Zhenqi , Monahan Richard
Published: January 2022

A theoretical model based on mechanics and machine dynamics is presented to describe the effect of machine stiffness on surface integrity of ground silicon nitride. Experimental results are also presented to verify the model. The damage depth of ground workpieces is assessed against different machine stiffnesses. The modeling and experimental results demonstrate that there exists a critical machine stiffness in grinding of ceramics. When machine stiffness is higher than the critical stiffness, no chatter should occur in the grinding process. In this case, damage depth increases with the increase of machine stiffness under the single pass grinding process. In contrast, if machine stiffness is lower than the critical stiffness, chatter can occur in the grinding process that may induce grinding damage. The theoretical model can also be used to predict the critical machine stiffness for other types of structural ceramics.
Robust Nonlinear Control Based on Describing Function Methods
Authors: Taylor James H.
Published: January 2022

The robust control problem for nonlinear systems is discussed from the standpoint of the amplitude sensitivity of the nonlinear plant and final control system. Failure to recognize and accommodate this factor may give rise to nonlinear control systems that behave differently for small versus large input excitation, or perhaps exhibit limit cycles or instability. Sinusoidal-input describing functions (sidfs) are shown to be effective in dealing with amplitude sensitivity in two areas: modeling (providing plant models that achieve an excellent trade-off between conservatism and robustness) and nonlinear control synthesis. In addition, sidf-based modeling and synthesis approaches are broadly applicable. Several practical SIDF-based nonlinear compensator synthesis approaches are presented and illustrated via application to a position control problem.
Closed-Form Optimal Controllers for Nonlinear Uncertain Systems
Authors: Krstić Miroslav , Deng Hua
Published: January 2022

We review our recent results on stabilization and optimal disturbance attenuation for nonlinear systems with uncertainties. The systems are affine in the control and the disturbance but otherwise general. We treat both deterministic and stochastic disturbances. In both cases the disturbance attenuation problem is posed as a differential game (in the stochastic case the player opposed to control is not the noise itself but its covariance). The results are based on control Lyapunov function techniques. The full account of the results is given in our new monograph (Stabilization of Nonlinear Uncertain Systems, Springer, 1998).
Development of NDE Technology for Health Monitoring of Load-Support Systems of Superconducting Magnets for MAGLEV
Authors: Aoyama Hiroshi , Watanabe Hiroyuki , Terai Motoaki
Published: January 2022

Magnetically levitated vehicles (MAGLEVS) using superconducting magnets have been under development in Japan. One of the load-support systems for the superconducting magnet consisits of a biconical, alumina-fiber-reinforced-plastic (FRP) structure. Safe operation of the superconducting magnet will be jeopardized if the mechanical condition of the load-support system begins to degrade. One of the factors that influences the soundness of the superconducting magnet is the stiffness of the load-support system. Here, it is important to know the relation between the degradation in stiffness and the growth of defects. So we carried out the fatigue test of the load-support system. The various defects (matrix cracking and delamination of FRP laminates) were revealed during this fatigue testing. Two types of non-destructive-evaluation (NDE) methods (ultrasonic evaluation and transmitted light technique through FRP) were applied to monitor and assess the soundness of alumina/epoxy load-support systems.
An Assessment of the Textile Preform Technology for Structural Composites
Authors: Chou Tsu-Wei , Kamiya Ryuta , Cheeseman Bryan A.
Published: January 2022

By reviewing the design methodology of textile structural composites, the relationship between the various textile forming techniques and some basic structural elements under various loading configurations is detailed. Additionally, an analytical technique to predict the stiffnesses of the resulting textile composite is discussed and a comparison between the predicted and measured in-plane stiffnesses for three different textile architectures is reviewed. Finally, an examination is made of the Mode I fracture toughness characterization of a stitched textile composite.
A Note on Helmholtz Attenuators With Air Cavity and Membrane
Authors: Wang Xiaodong , Feng Zhigang
Published: January 2022

In this paper, we present an analytical expression for the resonance frequency of Helmholtz attenuators with air cavity and membrane. We derive the characteristic equations based on one-dimensional isentropic acoustic models and illustrate the effects on the resonance frequency of certain design variations.
Active Vibration Isolation of Plate Structures Using a Kalman Estimator-Based Feed-Forward Controller
Authors: El-Sinawi Ameen H. , Kashani Reza
Published: January 2022

Active isolation of plate structures subject to base excitation using a novel Kaiman estimator-based, feed-forward controller is studied. The controller is always 2nd order irrespective of the complexity of the structure being controlled. Moreover, it does not require real-time adaptation and yet stays effective when the attributes of the base excitation change. Using the proposed controller, the vibration attenuation of a plate (the size of a computer board) with two different boundary conditions are demonstrated.
On Enhancing Eutectic Solder Joint Reliability Using a 2nd-Reflow-Process Approach
Authors: Chiang Kuo-Ning , Cheng Hsien-Chie
Published: January 2022

A three-dimensional solder liquid formation model is developed for predicting the geometry, the restoring force and the reliability of solder joints in an area array type of interconnects (e.g., ball grid array (BGA), flip chip) under various pad configurations. In general, the restoring force and the reliability of the solder joints depend on the thermal-mechanical behaviors of the solder, the geometry configuration of the solder ball, and the geometry layout/material properties of the package. A good solder pad configuration could lead to a larger restoring force along the gravitational direction (a higher standoff height and a blunter contact angle) with a better reliability characteristic achieved. In this research, a 2nd-reflow-process approach is applied for the reliability enhancement of typical BGA assemblies, including PBGA and SuperBGA assemblies. The results show that the 2nd-reflow-process approach could significantly increase the fatigue life of the solder joint.
Numerical Study on the Axial Flow Force of a Spool Valve
Authors: Wang Linxiang , Chen Ying , Lu Yongxiang
Published: January 2022

This paper studied the fluid flow in a spool valve numerically using the k-ε two-equation model of turbulent flow, while experimental results were drawn out by means of particles image velocimetry technology. The numerical result is compared with the experimental one to verify the viability of the numerical method. Based on many times calculations, it is found that the spool valve’s steady axial flow force can be reduced considerably just by modifying the relative position of the oil ports and buckets.
Experimental Evaluation of Noise due to Flow Over Surface Steps
Authors: Farabee Theodore M. , Zoccola Paul J.
Published: January 2022

This paper presents results obtained from an experimental investigation of noise generated by the passage of a turbulent boundary layer over two generic surface irregularities: a forward-facing step and a backward-facing step. Acoustic measurements were made in a low-noise wind tunnel using a directional microphone system. The experimental arrangement used is similar to that used for earlier studies of the surface pressures upstream and downstream of steps. Two step heights were evaluated and data were acquired for two free-stream velocities. One important finding is that although noise from the backward-facing step could not be measured above background levels, noise from the forward-facing step was readily detected and broadband in nature. Noise from the forward-facing step is found to originate from the immediate vicinity of the step and scales on the seventh power of velocity. The results from this study also demonstrate the utility of a directional microphone for radiated noise measurements in a wind tunnel.
Broadband Noise From a Propeller in a Turbulent Flow
Authors: Manoha Eric
Published: January 2022

Marine propellers, operating al the aft end of vessels, interact with the turbulent boundary layer developed along the whole length of the hull. This interaction results in fluctuations of blade angle-of-attack, inducing lift fluctuations which are known to be sources of radiated broadband noise. The prediction of this noise requires the knowledge of turbulence features like velocity integral length scales or wavenumber-frequency spectra. The aim of the present experimental/numerical study is to complete such a broadband aeroacoustic prediction in the case of a propeller operating at the conical end of an axisymmetric body.

A formulation of the propeller broadband radiated noise was derived from the dipolar term of the Ffowcs Williams-Hawkings equation. It uses the free field, uniform subsonic flow, acoustic Green’s function developed on its angular modes. It also includes the lift fluctuations induced on the blade sections, which may be classically written using a 2D Sears function, the propeller design (pitch, chord, skew, rake), and the wavenumber-frequency spectrum of the velocity component normal to the blade section.

To address this velocity wavenumber-frequency spectrum, the body was mounted in the ONERA F2 windtunnel for turbulence characterization based on 2-point measurements using a cross hot-wire probe and a Laser Doppler Anemometer (LDA). This specific instrumentation provided cross-correlations for various spacings in the axial, radial and tangential directions, at several locations in the turbulent field ingested by the rotating propeller. These data were used to adjust an analytical model of the velocity cross-correlation and of the corresponding velocity wavenumber-frequency spectrum.

In the last step, the same body and propeller were tested in the ONERA CEPRA 19 anechoic wind tunnel for acoustic characterization. The measured noise spectra were compared to the spectra predicted using the above turbulence measurements and formulation applied to the CEPRA 19 experiment conditions. Measured and predicted spectra are in good qualitative agreement but predicted noise levels slightly overestimate the measured values.
Free Bending Vibrations of Composite Base Plates or Panels Reinforced by a Non-Central Stiffening Plate Strip
Authors: Yuceoglu U. , Özerciyes V.
Published: January 2022

The problem of the free bending vibrations of a composite base plate reinforced by a bonded, non-central stiffening plate strip is considered. The lower composite base plate and the upper non-central stiffening strip are assumed to be dissimilar orthotropic Mindlin plates joined by a very thin and flexible adhesive layer. The entire composite plate or panel system has two opposite edges as simply supported while the other two opposite edges may have arbitrary boundary conditions. The governing partial differential equations are first reduced to a special set of ordinary differential equations in the first order form and, then, they are integrated by the “Modified Version of the Transfer Matrix Method”. The mode shapes and the corresponding natural frequencies of the stiffened composite plate or panel system are obtained for “hard” and “soft” adhesive layer cases. The natural frequencies of the system for several boundary conditions and parameters are studied. It was found that the hardness and the softness of the adhesive layer significantly influence the mode shapes and the corresponding natural frequencies.
Theory of the Compression Wave Generated When a High-Speed Train Enters a Tunnel
Authors: Howe M. S.
Published: January 2022

A review is given of the theory of the compression wave generated when a high-speed train enters a tunnel. The train is modeled by a distribution of monopole sources whose interactions with the tunnel portal determine the detailed characteristics of the wave. The waveform can be calculated exactly at subsonic train Mach numbers for a tunnel consisting of an unflanged cylinder of semi-circular cross-section, which has been the subject of extensive experimental study. An analysis of this case reveals how an approximate theory can be developed for arbitrary tunnel portals and train Mach numbers as large as 0.4. Details are given for flanged portals of both semi-circular and rectangular cross-sections. Nonlinear steepening in a very long tunnel is responsible for an intense, environmentally harmful, micro-pressure wave, which propagates as a pulse from the distant tunnel exit when the compression wave arrives, with amplitude proportional to the maximum gradient in the compression wavefront. The analytical theory permits the design of tunnel portals that greatly increase the initial wave thickness (thereby tending to inhibit wave steepening), either by flaring the portal, or by installing a tunnel entrance hood, which allows high pressure air produced by the train to be vented to the environment through windows in the side walls. A formula is given for the ‘optimum’ flared portal, which produces a pressure gradient across the wavefront that is constant and an overall minimum, so that the pressure in the wavefront increases linearly and provides the maximal protection against shock formation. The operation of tunnel entrance hoods is discussed in terms of a continuum model in which an axial section of the tunnel extending inwards from the entrance is perforated with a distribution of small apertures.
Convective Heat Transfer and Flow Mixing in Converging-Diverging Channel Flows
Authors: Guzmán Amador M. , Amon Cristina H.
Published: January 2022

Mixing and heat transfer enhancement due to chaotic advection in a converging-diverging channel flow is characterized and quantified by spectral element direct numerical simulations of the time-dependent Navier-Stokes, continuity and energy equations. The computational simulations are performed in a two-dimensional converging-diverging channel model composed of sinusoidal walls. Results are presented for laminar and transitional flow regimes, in the Reynolds number range 110 < Re < 600.

Eulerian and Lagrangian flow characteristics, such as vortex dynamics and Lagrangian Lyapunov exponents, are evaluated to characterize the flow pattern and to determine the chaotic mixing as a function of the Reynolds number. Heat transfer parameters, such as the temporal evolution of the temperature distributions and Nusselt numbers, are obtained to determine the heat transfer performance. Lagrangian Lyapunov exponent evaluations indicate that the onset of chaotic mixing occurs at Re∼130, as the flow evolves from a laminar to a transitional state. Results reveal that the heat transfer enhancement is due to chaotic mixing of fluid particles whose Lagrangian trajectories diverge exponentially fast. It is also found that chaotic mixing is stronger m the vortical regions and spreads to other flow regions as the Reynolds number increases.
Channel Flow in Porous Media in the Limit as Porosity Approaches Unity
Authors: Travkin V. S. , Catton I. , Hu K.
Published: January 2022

A mathematical model that predicts turbulent flow and heat transfer for plane two-dimensional channel flow in a porous medium in the limit as porosity approaches unity is developed. The development is carried out in two steps. The first is based on partial differential equations for momentum and energy conservation in the fluid and solid phases (two temperatures) in the channel derived from volume averaging theory (VAT) for a medium with a continuously changing of porosity and specific surface area. The second is to make changes to the porous layer morphology on the surfaces of the channel. After constructing closure models for the above equations, the features of momentum in the channel are shown to smoothly converge to the transport characteristics of a plane channel.
Heat Transfer Education: Keeping it Relevant and Vibrant
Authors: Khounsary Ali M. , Mondt James R. , Simon Terry , Agonafer Dereje , DeWitt David P. , Figliola Richard S. , Grosshandler William L. , Kreith Frank
Published: January 2022

The motivation for a fresh look at heat transfer education, both in content and in methodology, is generated by a number of trends in engineering practice. These include the increasing demand for engineers with interdisciplinary skills, rapid integration of technology, emergence of computerized and interactive problem-solving tools, shortening time of concept-to-market, availability of new technologies, and an increasing number of new or redesigned products and processes in which heat transfer plays a part. Examination of heat transfer education in this context can be aided by considering the changes, both qualitatively and quantitatively, in the student, educator, and researcher populations, employment opportunities, in the needs of corporations, government, industry, and universities, and in the relevant technical problems and issues of the day.

Such an overview provides the necessary background for charting a response to the difficult question of how to maintain excellence and continuity in heat transfer education in the face of rapid, widespread, and complex changes. The present paper addresses how to make heat transfer education more relevant and stimulating. This paper represents a written summary of a 1996 panel discussion at the 1996 International Mechanical Engineering Conference and Exhibition (IMECE) of the American Society of Mechanical Engineers (ASME) in Atlanta, Georgia, on “Heat Transfer Education: Keeping it Relevant and Vibrant,” with significant expansion and amplification by the authors and the panelists in the 1997–98 period.

The consensus of the participants is that the steps necessary to ensure the desired outcome in heat transfer education should include: (1) a better understanding of the interaction between the student, course content, and market needs; (2) an appreciation of the need in multidisciplinary industrial environments for engineers trained with a broad background; (3) a revision of the introductory heat transfer course to incorporate illustrative and insightful industrial examples and case studies reducible to order-of-magnitude analyses; (4) a reinforcement of real-world problem-solving abilities in students by introducing them to examples that emphasize multidisciplinary issues in modern thermal management problems; and finally (5) industrial collaboration that would provide the educator with meaningful thermal management case studies (and possible funding), the student with an appreciation of industrial practices, and the industrial sponsor with access to academia for assistance in problem solving. Also suggested is an effective regular review program to provide assessment, feedback, and suggestions for quality control to interested institutions on their teaching methodology and materials.
Micro Channel Heat Exchanger for Cooling Electrical Equipment
Authors: Kawano Koichiro , Minakami Ko , Iwasaki Hideo , Ishizuka Masaru
Published: January 2022

The micro channel heat exchanger, which has many small channels (10–100 μm order), is a promising device to cool an integrated circuit, which generates a large amount of heat. In order to investigate the performance of the micro channel heat exchanger, three-dimensional numerical simulations and experiments on heat transfer behavior and pressure loss were carried out. So far as the heat transfer phenomena is concerned, results obtained using a silicon tip micro channel model a very small thermal resistance, about 0.1(K cm2/W) at Re = 300. And, in the designing of heat exchanger, the pressure loss phenomenon is of practical importance. In the present study, measured pressure loss was good agreement with that of analytical result obtained on the basis of fully developed laminar pipe flow assumption.

Furthermore, a practical setup was made with a micro channel heat exchanger to clarify the possibility of using the micro channel heat exchanger in electrical equipment. As a result, it was confirmed that the performance of the micro channel heat exchanger system is sufficient to cool a silicon chip which generates a large amount of heat, and the scale of the system is compact compared to that of the whole setup of electrical equipment.
Heat Transfer in Generator Armature Bar Region Near a Resistance Temperature Detector
Authors: Tong Wei
Published: January 2022

This paper presents a simplified heat transfer analysis of the generator armature bar region near a resistance temperature detector (RTD). During generator operations, heat is generated in the generator due to the various losses. With conventional indirect cooling, heat is removed from copper conductors to the steel core through the conductor insulation. It is desired to minimize the thermal resistance to achieve the highest heat transfer rate.

Heat transfer characteristics in the generator armature bar region were obtained using an FEM model. Results show that the RTD temperature is primarily determined by the boundary temperatures on the copper conductor and silicon-iron walls, and thermal conductivity of RTD and armature bar insulations. Sensitivity studies have been performed to help engineers to optimize generator designs.
Investigation of Enhanced Heat Transfer in Low Reynolds Number Flows in a Plate Heat Exchanger
Authors: Muley Arun , Manglik Raj M.
Published: January 2022

Steady-state heat transfer and pressure drop data for single-phase low Reynolds number flows (2 ≤ Re ≤ 400) in a plate heat exchanger (PHE) with chevron plates are presented. Three different chevron plate arrangements, with two symmetric (β = 30°/30° and 60°/60°) and one mixed (β = 30°/60°) plates, are considered in a single-pass, U-type, counter-flow PHE. The effects of the corrugation inclination angle β, and flow conditions on Nu and f characteristics of the PHE are investigated using vegetable oil as test fluid (130 < Pr < 290). The results indicate that as β increases, up to 3 times higher Nu are obtained in chevron plates compared to an equivalent flat-plate pack; the concomitant f, however, are up to 9 times higher. Correlations of the functional form

Nu(Re, Pr, β, de/L, μ/μw) and f(Re, β)

are developed, and they predict all available data within ±10%. Finally, the performance of chevron plates is evaluated relative to an equivalent flat-plate channel for two different operating constraints: (1) Fixed geometry and constant pumping power, and (2) fixed heat load and pressure drop.
Effect of Porous Fin in a Plate-Fin Heat Exchanger
Authors: Kim Seo Young , Kim Jin-Ho , Kang Byung Ha
Published: January 2022

The present experimental study investigates the impact of porous fin on the pressure drop and heat transfer in a state-of-the-art plate-porous fin heat exchanger. Systematic experiments have been carried out in a simplified model of plate-porous fin heat exchanger at the controlled test environment. The porous fins are made of aluminum-alloy foam materials with several permeabilities and a high porosity. The experimental results show that the porous fins can enhance the performance of plate-fin heat exchangers. The pressure drop and the heat transfer coefficients are significantly affected by the permeability of porous fin. The simple correlations of friction factor and Colburn j-factor are also given for future design purpose.
Molecular Tagging Velocimetry Applied to Buoyancy-Driven Convective Phenomena During Solidification
Authors: Wirtz K. , Koochesfahani M. , McGrath J. J. , Benard A.
Published: January 2022

Molecular Tagging Velocimetry (MTV) has been applied to quantify velocity fields associated with convective phenomena which occur during solidification in aqueous ammonium chloride solution (NH4Cl-H2O), a popular transparent low-temperature analog of metal alloys.

A phosphorescent line pattern was “written” into the melt to quantify one component of the velocity field within a plume and in the fluid surrounding the plume. These results represent the first quantitative, continuous field measurements of velocity for such studies. The data compare well with the magnitude of the maximum plume velocities estimated in the literature using particle tracking methods. Asymmetric and symmetric plume velocity profiles were quantified. Velocity fields associated with downward flowing sheaths of fluid surrounding the plume were quantified. Although the shape of the velocity profile measured using MTV compares reasonably well with that predicted by an analytical model proposed in the literature, significant differences were detected. The extension of the MTV method using a tagged plane, rather than a tagged line of phosphorescent fluid, for qualitative 3-D dynamic, visualization is described. This realization of the MTV method has the potential for revealing the basic three-dimensional structure of the velocity field.

The results presented here demonstrate that it is feasible to apply MTV as an advanced diagnostic measurement method to further improve our knowledge of convective phenomena which occur during solidification.
Dynamical Behavior of Slug Initiation Generated by Short Waves in Two-Phase Air-Water Stratified Flow
Authors: Ansari Mohammad R.
Published: January 2022

Two-phase air-water stratified flow was studied in a horizontal duct. The two-phase air-water flow was considered under atmospheric conditions. The non-linear field equations for air and water were coupled and solved using a finite difference method For this purpose, the two-phase flow analyzer ‘MINCS’ which was initially developed by Japan Atomic Energy Research Institute was used. The initial and boundary conditions were established in order to create a slug. The criterion for two-phase stratified flow instability was compared with the instability criteria based on linear analysis and the empirical correlations of other researchers. It was found that the gas velocity required for initiation of slugging is much lower than defined by the Kelvin-Helmholtz instability criteria. But the instability criteria for the on set of slugging agreed well with Mishima and Ishii prediction. The reason for the necessary lower air velocity in comparison with Kelvin-Helmholtz relation is the growth of short waves which create slugs which is discussed here. The dynamical behavior of slug initiation which was generated by short waves was presented. The results showed that as void fraction was decreased, slug generated with lower air velocities in a shorter duct length and in a shorter period of time with a bigger wetted area. Also, the higher air velocities create slug with higher growth rate in a shorter duct length.
Study of Heat Flux Gages Using Sensitivity Analysis
Authors: Dowding Kevin J. , Blackwell Ben F. , Cochran Robert J.
Published: January 2022

The response and operation of a heat flux gage is studied using sensitivity analysis. Sensitivity analysis is the process by which one determines the sensitivity of a model output to changes in the model parameters. This process uses sensitivity coefficients, which are defined as partial derivatives of field variables (e.g. temperature) with respect to model parameters (e.g. thermal properties and boundary conditions). Computing sensitivity coefficients, in addition to the response of a heat flux gage, aids in identifying model parameters that significantly impact the temperature response. A control volume finite element based code is used to implement numerical sensitivity coefficient calculations, allowing general problems to be studied. Sensitivity coefficients are discussed for the well known Gardon gage.
Validation of Methodologies for the Estimation of Blood Perfusion Using a Minimally Invasive Probe
Authors: Robinson Paul S. , Scott Elaine P. , Diller Thomas E.
Published: January 2022

Parameter estimation techniques have been utilized in the development of methodologies to noninvasively measure blood perfusion using a new thermal surface probe. The core of this probe is comprised of a small, lightweight heat flux sensor that is placed in contact with tissue and provides time-resolved signals of heat flux and surface temperature while the probe is cooled by air jets. Parameter estimation techniques were developed that incorporate heat flux and temperature data with calculated data from a biothermal model of the tissue and probe. The technique simultaneously estimates blood perfusion and thermal contact resistance between the probe and tissue. Validation of this concept was carried out by experimentation with controlled perfusion through non-biological porous media. A controlled rate of uniform flow of warm water through a fine pore sponge provided a phantom model for blood perfusion through biological tissue. The parameter estimation technique was applied to measurements taken over a range of flow rates. Heat flux and temperature measurements and the resulting perfusion estimates correlated well with the experimentally imposed perfusion rate. This research helps establish the validity of using this method to develop a practical, noninvasive probe to clinically measure blood perfusion.
Optimization of Enhanced Steam-Ejector Applied to Steam Jet Refrigeration
Authors: Kouremenos D. A. , Rogdakis E. D. , Alexis G. K.
Published: January 2022

Ejectors are used for a wide range of applications. Refrigeration systems have, a long established history. Ejector refrigerators working on steam or halocarbon refrigerants provide a high level of flexibility. Ejector can also be used in solar-powered refrigeration systems and absorption-refrigeration systems.

There are very few comprehensive theoretical studies even though several models for ejectors in literature. A new ejector theory was developed by Munday and Bagster (1977). This theory depends on the assumption of two discrete streams, the motive stream and the secondary stream. The two streams maintain their identity down the converging duct of the diffuser. At some section the secondary flow reaches sonic velocity. The shocking and mixing occur at the very end of the converging cone resulting in a transient supersonic mixed stream. There is no supersonic deceleration and a shock takes place immediately on mixing. The mixed stream will shock to the subsonic, found by the intersection of the Fanno and Rayleigh lines. After that the stream is brought to near zero velocity in the diffuser.

In the present work this theory is used as a basis, in order to develop a computerized model of ejector with particular reference to steam-ejector at various operating conditions. The results are compared with available from the literature experimental data. Also a parametric study is conducted in order to reveal the influence of the various parameters on the performance of the steam jet refrigeration.
Intelligent Computer Aided Design, Analysis and Improvement of Combined Cycle
Authors: Wu C.
Published: January 2022

This paper describes the use of an ICAI (Intelligent Computer Aided Instruction) software package for the design, analysis and improvement of the combined cycle. The traditional cycle design and analysis is long and tedious. Obtaining an accurate combined cycle performance quickly is necessary in the design process. Objectives for improvements which cannot be easily accomplished using the conventional method are emphasized. As an example of the capabilities of the package, the design, analysis and improvement of an innovative Brayton/Ericsson cycle are given.
Impact of Gas Turbine De-Rating on the Performance and on the Economics of Big-GT Cycles
Authors: Walter Arnaldo , Llagostera Jorge , Gallo Waldyr L. R.
Published: January 2022

Biomass gasification and the sequential use of the produced gas in gas turbines (the so called Biomass Integrated Gasifier - Gas Turbine cycles) is one of the technologies that can minimize carbon dioxide emissions during electricity generation.

As the primer mover of such power plants, gas turbine performance is a key parameter on the economics of BIG-GT systems. At least within the first generation of this technology, gas turbines originally designed for burning conventional fuels (natural gas and light oils) will be adapted to syngas burning. At this stage some changes on combustion chamber will be required, and some modifications on operational control parameters must be done as well. Gas turbine de-rating (reduction of gas turbine firing temperature) is the simplest control alternative to avoid problems concerned with reduction of compressor surge margin and increased thermal loads. However, from the performance view point of the gas turbine (and also for the whole system), this seems to be the worst option.

In this paper the de-rating alternative is analyzed both from a thermodynamic and an economic point of view. A BIG-CC system based on a nearly atmospheric air-blown gasifier is considered. De-rating is analyzed vis-à-vis moderate increases of compressor pressure ratio. A simulation code (developed by the authors) able to perform analysis of thermal power systems (and particularly BIG-GT systems) is applied on this study. Cost functions are used to estimate the total installed unit capital cost, allowing a proper evaluation of electricity generating costs. The results indicate that electricity costs are sensitive to de-rating either due to the reduction on electricity generating efficiency and to the increase on the unit capital cost.
A Survey on GHP Technology
Authors: Dentice d’Accadia Massimo , Sasso Maurizio , Sibilio Sergio
Published: January 2022

The Gas engine driven Heat Pump (GHP) basically consists of a reversible vapour compression heat pump with an open compressor, driven by an internal combustion gas fueled engine instead of an electric engine.

The possibility of recovering waste engine heat via a jacket and an exhaust heat exchanger, together with the use of an alternative engine closely follows the heating building load varying the engine speed continuously, can be regarded as the most important peculiarities of this equipment: these features allow higher performances and lower running costs than Electric Heat Pump (EHP).

In this paper the results of the study and research performed by the DETEC Department of the FEDERICO II University of Naples are reported; the main goal of the research was the assessment of the on-site small GHP performance but, a wider analysis on GHP was performed, covering some related topics: the historical development and market situation, the reasons for GHP use, and finally, the metrological and performances analysis.
Evaluation of the Acoustic Properties of Silica Aerogels
Authors: Conroy John F. T. , Hosticka Bouvard , Davis Scott C. , Norris Pamela M.
Published: January 2022

The acoustic transmission velocity in silica aerogel was measured as a function of the gas type and pressure in the aerogel pores. This was done with air-coupled ultrasonic transducers configured for differential pulse transit time measurements. At high pressures, the fractional reduction of acoustic velocity as a function of mean free path is identical in different gasses. This may indicate a thermal relaxation phenomenon, with the relaxation time dependent upon the rate of collision between gas molecules and the silica pore walls.
Some Experiments on the Fracture Behavior of Microcellular Polycarbonate
Authors: Barlow Chris C. , Bordia Rajendra K. , Flinn Brian , Weller John E. , Kumar Vipin
Published: January 2022

The fracture behavior of microcellular polycarbonate (PC) was investigated. A work of fracture test was conducted on double-edge-notched-tension (DENT) specimens and this produced reliable tensile failure data the work of fracture was found to decrease linearly with foam relative density. A critical initiation stress intensity factor Kc was calculated from fracture toughness tests in which compact tension specimens were pulled in tension. In all tests, the impact/fracture behavior of these foams was a strong function of foam density.
In-Line Measurement of Gas Solubility in Polystyrene and Polyethylene Terephthalate Melts During Foam Extrusion
Authors: Zhang Qiang , Xanthos Marino , Dey Subir K.
Published: January 2022

In this paper, a new in-line method was used to directly measure the gas solubility in polymer melts during foam extrusion. Metered quantities of polymer and specific gases were blended in a single screw extruder which is capable of producing polymeric foams of variable density. A specially designed optical window and flow restrictor valve placed between the die and the end of the extruder were used to generate dynamic solubility data by observing the onset of bubble formation/dissolution at the window through a microscope-CCD camera-monitor/recorder system. Solubility data were determined for systems involving nitrogen, argon and carbon dioxide in polystyrene and polyethylene terephthalate at different temperatures. Good agreement with literature data on the PS-CO2 system was obtained.
Large Displacement Piezoelectric Actuator Configurations
Authors: Dancila D. Stefan , Armanios Erian A.
Published: January 2022

In the present work three configurations of compact size, large rotation piezoelectric bimorph actuators are proposed and analyzed, and their static response to control voltage is analytically modeled. The actuator configurations can be characterized as thin, coiled, single curvature bimorph piezoelectric shells with thickness polarization and electroded faces. Compared to a cantilevered bimorph, the configurations analyzed in this work are more compact and allow an increase in actuator displacement output — in this case a rotation — without degradation of blocked moment output. The analytical models developed are verified by comparison with finite element results for a set of generic geometric parameters defining each of the three configurations. Relevant electroelastic properties of a typical piezoelectric material are assumed. An excellent correlation of results is found, confirming the accuracy of the analytical modeling of response as well as the large rotation capability of this class of actuators.
Automotive Composites Consortium Generic Tube Crush Program: Resin Transfer Molded Tubes
Authors: Browne Alan L. , Houston Dan Q. , Watling Patrick J. , Lalik Larry
Published: January 2022

This paper provides a brief summary of the major findings of the RTM (Resin Transfer Molding) portion of a generic tube crush study conducted by the Energy Management Working Group (EMWG) of the Automotive Composites Consortium (ACC). A total of 147 crush tests were performed on 55 × 55 mm square hollow tubes using plug-type crush initiators. The principal fiber was E-glass and the resin used was Dow Derakane 411-C50 vinylester. Parameters considered were tube fiber architecture and wall thickness, test crush rate — static vs. dynamic —, and test temperature/humidity. Principle findings were that fiber architecture, tube wall thickness, and whether the test was a static or dynamic crush test all can produce significant differences in tube crush force and specific energy absorption (SEA); also that both tube quality and postcuring are strongly linked to the quality and generality of the information gathered/conclusions that can be drawn.
Development of a Composite Front Structure for Automotive Crashworthiness
Authors: Botkin Mark , Browne Alan , Johnson Nancy , Fidan Sukru , Jeryan Richard , Mahmood Hikmat , Wang Richard , Lalik Larry , Peterson Doug
Published: January 2022

This paper will summarize the results of a major project of the Automotive Composites Consortium (ACC) to focus on the use of composites in a vehicle front-end structure. The emphasis of the project was to replace the entire steel front structure of a production automobile with a molded composite front structure. The project focused on the development of a completely new reinforcement architecture which emphasized production feasible preforming methods: triaxially braided glass fibers over foam cores make up the upper and lower rails and the connecting panel can be formed from either thermoformed continuous strand mat or directed fiber, and utilized an Resin Transfer Molding (RTM) process. The front structure of the vehicle was redesigned and replaced with production-feasible composite components designed for crash energy management requirements as well as other overall structural considerations. The paper will describe the many design, analysis and test phases of the project which led up to a successful barrier test to verify structural crashworthiness. A fully dressed and instrumented vehicle was built up to incorporate the composite front structure and the vehicle was barrier crash tested at 56 kph. The vehicle passed the test — all performance measures were well within the Federal MVSS requirements — and all but one measure yielded improved performance over the all-steel production vehicle. In addition, the composite parts are 25% lighter than the steel parts they replace.
An Exit Burr Model for Drilling of Metals
Authors: Saunders L. Ken Lauderbaugh , Mauch Craig A.
Published: January 2022

The mechanics of the formation of exit burrs for drilling metals are analyzed. A burr formation model is developed where the material in front of the drill is modeled as a circular plate of varying thickness. The drilling thrust force is distributed as a pressure along the plate. Material removal continues until a failure condition is reached. At the point of failure of the plate the remaining material is bent out to form the burr. The model also includes temperature effects. Experimental verification was conducted on 2024-T351 aluminum and on 7075-T561 aluminum. Two types of drill geometry were considered. The model accurately predicts the trends in the data However, the burr formation model over predicts the magnitude of the burr due to the failure criteria chosen and the limitations of elastic plate models.
Global Coordinate Method for Determining Sensitivity in Assembly Tolerance Analysis
Authors: Gao Jinsong , Chase Kenneth W. , Magleby Spencer P.
Published: January 2022

Tolerance sensitivity indicates the influence of individual component tolerances in an assembly on the variation of a critical assembly feature or dimension. Important applications include assembly tolerance analysis and tolerance allocation. This paper presents a new method for determining tolerance sensitivity using vector loop assembly tolerance models. With a vector loop model, the assembly kinematic constraints or assembly functions can be established automatically as implicit functions. This method evaluates the derivatives of the kinematic constraint equations with respect to both manufactured dimensions and assembly variables. The derivative matrices are then used to calculate the tolerance sensitivity matrix. This is a closed form method which relates the derivatives of the assembly functions to the coordinates of the joints or nodes and the orientations of the vectors and the local joint axes in an assembly. It is accurate, simple and very suitable for design iterations.