bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Work of Breathing in a Nonlinear Human Lung Model
Authors: Athanasiades A. , Ghorbel F. , Clark J. W. , Niranjan S. C. , Liu C. H. , Zwischenberger J. B. , Bidani A. 
Published: March 2022

Abstract
Work of breathing (WOB) functions associated with the mechanics of breathing are identified, based on a nonlinear model of the human lung and using a Lagrangian approach. Total and dissipative WOB values are computed numerically for three spontaneous breathing maneuvers (tidal, panting and forced vital capacity) of the same subject. An additional simulation reveals the effect of changing lung tissue compliance on WOB. The energy analysis provides valuable insight into the mechanics of respiration, and, in particular, the significance of individual model components. It provides the basis for sensitivity and optimization studies of the respiratory function, especially in the context of evaluating ventilator-dependent patients.
Vibration Cancellation in Complex Support Structures for Precision Robots
Authors: Rhim Sungsoo , Book Wayne 
Published: March 2022

Abstract
This paper examined the effectiveness of the Optimal Arbitrary Time-delay filter applied to cancel the undesired elastic modes of vibration in complex supporting structures for a precision robot which is under development. To achieve the desired positioning precision, suppressing the structure vibration is essential. For this to be done Optimal Arbitrary Time-delay (OAT) filtering method was chosen. Modeling of the system has been performed and using this model, simulations were done without and with the OAT filter. The ability of OAT filter to cancel the vibration of the structure was demonstrated in the simulation results. To verify the simulation, an experiment including an OAT filter within the robot control system has been done on the current version of the precision robot. Even though the dynamic response of the supporting structure in the precision robot system is inherently of small magnitude and high natural frequency, response due to the filtered command showed that the filter successfully reduced vibration in magnitude and got rid of the residual vibrations faster than the response with the unfiltered command.
Sliding Mode Control of a Magnetically Levitated Fast-Tool Servo System
Authors: Gutierrez Hector M. , Ro Paul I. 
Published: March 2022

Abstract
Magnetic Servo Levitation (MSL) is currently being investigated as an alternative to drive fast-tool servo systems that could overcome the range limitations inherent to piezoelectric driven devices while operating over a wide bandwidth. To control such systems, a feedback-linearized controller coupled with a Kalman filter has been described. Performance limitations that degrade tracking accuracy suggest the use of a more robust controller design approach, such as sliding mode design. Current literature on sliding mode deals almost exclusively with systems that are affine on the input, while the magnetic fast-tool servo is nonlinear on it when the control action is current command. This paper discusses two sliding mode-based controllers, one that overcomes the aforementioned problem by using a modified sliding condition to calculate control action, and a second one that uses affine control command by operating in voltage mode.
Control of I.C. Engines for Emissions and Idle Speed Regulation
Authors: Shah Minesh A. , Franchek Matthew A. 
Published: March 2022

Abstract
Presented in this paper is a controller design methodology for simultaneously regulating engine idle speed and air-fuel ratio in the presence of an external non-measurable torque load disturbance. Hammerstein type models are used to characterize the nonlinear dynamics associated with the air and the fuel entrainment process. A feedback and feedforward control approach based on describing functions is used to achieve the performance goal of maintaining the engine idle speed within a prespecified output tolerance while limiting excursions in the air-fuel ratio.
Model Predictive Control for Active Suspensions: Controller Design and Experimental Study
Authors: Gopalasamy Srinivasan , Osorio Carlos , Hedrick Karl , Rajamani Rajesh 
Published: March 2022

Abstract
This paper discusses the design of a Model Predictive Controller for a vehicle active suspension system and presents the experimental results obtained in the evaluation of the controller performance. The Model Predictive Control methodology described here, utilizes the road profile ahead of the vehicle as preview information and also takes into explicit consideration the physical constraints on the suspension travel. The advantages in the use of preview information in active suspension control have been studied by several researchers. The explicit consideration of the physical limits on the suspension travel becomes an important factor under rough road conditions such as the ones encountered by off-road vehicles. A computationally efficient version of the predictive controller was developed so as to be implementable on-line. The experimental evaluation of the controller was performed on the UC Berkeley Active Suspension Test Rig.
Fuzzy Logic Semi-Active Control of a Suspension for Off-Road Vehicles
Authors: Kashani Reza , Strelow Joseph E. 
Published: March 2022

Abstract
A fuzzy-logic approach to semi-active vehicle suspension design is developed, with the goal of improving the speed of the vehicle over very rough, off-road, terrain. The ride metric used for quantifying improvements is the absorbed power of the sprung mass of the vehicle. Particular attention is made to the proper modeling of the suspension using both the full kinematic constraints and the more convenient two degree of freedom model of the quarter vehicle suspension. Nonlinearities of the suspension, including tire stiffness and bumpstops are included at all stages to demonstrate the controller performance advantages. The semi-active control law is developed on the less complex model, and the results of tuning in the fully constrained environment are compared.
The results of this work have broad appeal, from the ease of development of the fuzzy-logic based algorithms, to the cost effectiveness of the semi-active hardware implementation. Improvements in the performance of the suspension system are desirable to the increasingly popular sport utility and light truck markets, as well as to military and emergency vehicle designs.
Statistical Energy Analysis Model and Connectors for Automotive Vibration Isolation Mounts
Authors: Byam Brooks P. , Radcliffe Clark J. 
Published: March 2022

Abstract
Consumer comfort is a top priority in today’s vehicle design. Reduction of noise and vibration enhances comfort and improves the overall quality of the vehicle. Linear elastic vibration isolation mounts are traditionally applied within complex structures to combat noise and vibration. Statistical Energy Analysis (SEA) is becoming an established and tested noise and vibration modeling methodology that is frequently used to model the flow of noise and vibration in complex structures. A SEA model of a linear elastic vibration isolation mount is developed here which enables SEA analysis of elastically isolated systems for the first time.
A vibration isolation mount model has been absent from SEA models because of the lack of an SEA formulation. Linear elastic vibration isolation mount SEA equations are developed here for the first time. The basis of SEA theory is energy sharing among vibrational mode groups. Traditionally, vibration isolation mounts were thought of as compliant elements with no modes suitable to SEA analysis. An example mount is defined and the number of energy storage modes computed. The results show that a linear elastic vibration isolation mount should be modeled in SEA analysis and provide the equations for a SEA isolation mount model. Also included is the analysis for three unique SEA connectors, a mount to acoustic volume connector, a beam to mount connector, and a mount to flat plate connector.
Velocity Profiles Through and Over Arrays of Impermeable Cylinders
Authors: Bijeljic B. , Sederman A. G. , Mantle M. D. , Gladden L. F. , Papathanasiou T. D. 
Published: March 2022

Abstract
We study experimentally (through the non-intrusive technique of Magnetic Resonance Imaging - MRI) and computationally (using the Boundary Element Method - BEM) the distribution of fluid velocities across square arrays of uniform cylinders placed inside a Hele-Shaw cell and oriented with their axes perpendicular to the direction of flow. To simulate the presence of gaps between mold walls and preform in liquid composite molding applications, the cylinders are placed in such a way that an open channel, narrow enough to force a significant part of the flow through the array but wider than the distance between individual cylinders, exists in one side of the array. We are interested in the distribution of velocity in these systems and in particular, the distribution of flow between the two regions (that is, the ‘open’ channel and the cylinder array) and in any velocity transitions from the ‘open’ channel to the interior of the array. Both experimental and computational results show that, for the size of cylinders studied, this transition is complete within the first row of cylinders. Thus, we have not been able to detect any transitions from open-channel flow to flow inside the cylinder array; this will require use of larger number of smaller cylinders. Model predictions are in reasonable agreement with measurements; the observed discrepancies point towards stringent design requirements for such flow cells if the obtained information is to be quantitatively useful.
Ensemble Averaging Technique in the Mechanics of Suspensions
Authors: Buyevich Yu. A. , Theofanous T. G. 
Published: March 2022

Abstract
An approach based on ensemble averaging ideas is elaborated for suspensions of fine particles in a Newtonian fluid. Both field conservation equations and constitutive laws are derived within a unified theoretical frame. The structural form of the field averaged equations of conservation and interpretation of their various terms, particularly phase stresses and interphase interaction force constituents, are clearly revealed. The approach is suggested as an effective paradigm for better understanding of and extending to more complex multiphase flow and heat transfer situations.
Rheological and Thermal Properties of Phenolic Resin and Polymeric Isocyanate and Their Blends
Authors: Bakhtiyarov Sayavur I. , Overfelt Ruel A. 
Published: March 2022

Abstract
Viscous and thermal properties of a phenolic resin (Part I) and a polymeric isocyanate (Part II), and their blends were investigated by using rotational viscometry. The elastic properties of the blends were investigated by means of a jet thrust technique, using a straight tube. The rheological and thermal properties of the blends were dependent on the blend composition. Although both materials are Newtonian liquids, their blends exhibit non-Newtonian liquid flow behavior and elasticity. A thermo-reaction has been observed and investigated after mixing the two parts.
Numerical Prediction of the Molding of Composite Parts
Authors: Dupret F. , Verleye V. , Languillier B. 
Published: March 2022

Abstract
This paper concerns the prediction of the effect of Hele Shaw flow upon the orientation of a suspension of short fibers. A numerical method to solve the decoupled free boundary flow problem and to calculate the fiber orientation is elaborated. Recent developments in the theory of the 3D natural closure approximation are presented and discussed.
Finite Strain, Visco-Elastic Constitutive Models for Kinematically Constrained Materials
Authors: Martin Todd A. 
Published: March 2022

Abstract
The manufacture and increasingly widespread use of thermosetting/thermoplastic pre-preg fabrics suggests that new finite strain material models are needed to describe their behaviour during forming. Determining the appropriate models to apply involves the correct description of the anisotropic visco-elastic behaviour of these materials and the development of methods for measuring the material properties. This paper addresses the former issue, by presenting a logical method for formulating the equations of state for an incompressible continuum reinforced with inextensible fibres. Utilising body tensor fields and the internal variable concept, various thermo-rheological constitutive models are derived, based on the free energy and the dissipation function, which arise naturally in the Clausius Duhem inequality. The inherent assumptions leading to the finite strain Maxwell and Kelvin-Voigt material models are discussed. The method outlined here is general, therefore it allows the formulation of constitutive equations with a clear understanding of the limitations embodied in the resulting models.
Electrorheological Fluids Under AC and DC Excitation and the Influence of Solid Phase Size
Authors: Sproston John L. , Wahed Ali K. El , Stanway Roger 
Published: March 2022

Abstract
This paper is concerned with an experimental investigation of a comparison of the rheological performance of an ER fluid in oscillatory squeeze-flow under DC and AC conditions. The fluid is sandwiched between two parallel plane electrodes, the upper one stationary and the lower one oscillating normal to its plane. The magnitude of the transmitted force across the fluid in the AC case is seen to be highly dependent on the shape of the input waveform and on the electrical excitation frequency. In all cases this force is found to be smaller than that seen in the corresponding DC case.
It is seen that the performance of the ER fluid depends dramatically on the size of the dispersed solid phase and has an optimum value which is dependent on the inter-electrode gap. Finally the implications of the results to vibration control and the trend of future work into squeeze flow behaviour are discussed.
On Short Wave Elastic Instabilities in Parallel Plate Flow
Authors: Olagunju David O. 
Published: March 2022

Abstract
The purely elastic instability of torsional flow a viscoelastic fluid confined between two coaxial parallel plates is considered. This problem is analyzed in the limit of small aspect ratio α = h/a, and zero Reynolds number where h is the plate separation and a is the plate radius. In this limit we derive a set of equations which can be solved analytically for the Oldroyd-B model. Our analysis shows that stability is controlled by a local elasticity number ε≡rλ2ϖ2/α, where r is the local radius, γ is the relaxation time and ϖ is the constant rotation rate. For ε less than some critical value εc the flow is linearly stable. As ε increases past this critical value the flow loses stability to a time dependent oscillatory mode. The most dangerous mode has a short wave length of the order O(α). Our results are in good agreement with those of Oztekin and Brown (1993) and Byars et al. (1994). A criterion to ensure stability to infinitesimal disturbances is proposed.
The Effect of Temperature and Humidity Exposure on Adhesion
Authors: Pearson R. A. , Hydro R. M. , Lloyd T. B. , Nied H. F. 
Published: March 2022

Abstract
Silver-filled organic adhesives are commonly used in the microelectronics industry to bond silicon chips to a wide variety of substrates. The substrates include copper, silver, nickel / palladium, polyimide, and glass-filled epoxies. In this presentation, we will examine the effect of temperature and humidity exposure on the adhesive strength between silver-filled epoxies and copper leadframe substrates. Both a mixed-mode bending specimen (MMB) and a width-tapered double cantilever beam specimen (WT-DCB) are used to determine the adhesive strength in terms of an interfacial strain energy release rate (interfacial fracture energy). The interfacial fracture energy is found to decrease significantly at high temperatures (230 C, which is typical for solder reflow) and after 168 hrs humidity exposure (85 %RH / 85 C). The origins for this behavior will be discussed.
Reliability of Underfill-Encapsulated Flip-Chip Packages
Authors: Doi Hiroaki , Kawano Kenya , Yasukawa Akio , Sato Toshihiko 
Published: March 2022

Abstract
Reducing the plastic strain in solder joints is necessary to prolong the life of the joints during the thermal cycling test for flip-chip packages. Without heat spreaders, it is known that underfills with suitable mechanical properties reduce the plastic strain in the solder joints for underfill encapsulated flip-chip packages. From the stress analyses of the heatspreader fixed packages, it is shown that although the heat spreader increases the strain in the joints, the underfills also have an effect on the reduction of the joint strain. Furthermore, the mechanical properties of the underfill that produces the least strain in the joints are the same as those for packages without heat spreaders.
For the heat spreader fixed package, the delamination between the solder joint and the chip surface occurs. This is caused by the extension of the delamination in the interface between the underfill and the chip surface. From the stress analyses, it is made clear that this delamination is due to the stress in the underfill at the edge of the chip and this stress is significantly affected by the fillet shape of the underfill.
Thermal cycling tests were conducted to relate the FEM analysis results with those of the tests. The effects of the heat spreader, the mechanical properties of the underfill, and the fillet shape of underfill on the mode of fracture and the life of the solder joint are investigated.
Stress Analysis of High Density Bare Chip Packaging Technologies
Authors: Tsukada Yutaka , Mizumoto Shogo , Kodama Yasuyuki , Nishimura Hideo 
Published: March 2022

Abstract
A bare chip packaging with an encapsulated flip chip joint on an epoxy base carrier is now emerging into an electronic packaging industry due to its high density, high performance and low cost capability. Generally, one of the key points of the bare chip packaging is to overcome thermal stress caused by a mismatch of coefficient of thermal expansion (CTE) between the chip and carrier. Initially, a ceramic carrier was used because of its low CTE which minimizes the mismatch of CTE. A technical break through was made to use an epoxy base carrier as the chip carrier instead of ceramic one by resolving a large CTE mismatch with an epoxy encapsulant which fills the space between the chip and carrier [Tsukada et al., 1992].
This technology is basically applied to implement a package of bare chip attach on mother board and now expanding to provide a chip attach in a BGA package. Though such packages are become to be used for various products, the reliability characteristics are not sufficiently explored yet. This paper describes the solder joint life comparison as the one of such items between these two package types, bare chip and BGA on planar, and two way of assembling to carrier, single side and double side assembly.
Comparison of Acoustic Microscope, X-Ray Radiography, Dye Penetrant and Destructive Physical Analysis Data for Die Attachment Analysis
Authors: Gilmour Duane A. , Reilly James F. , Calabrese Donald W. 
Published: March 2022

Abstract
This paper addresses the analysis of die attach disbonds (delaminations) of silicon die in a multichip module (MCM). A silicon die attached to a silicon substrate in an MCM requires good adhesion for thermal dissipation and reliability purposes. Traditionally, die attach is evaluated by destructively measuring adhesion or non-destructively measuring voiding through x-ray radiography. For this paper, non-destructive acoustic microscopy and destructive dye penetrant testing were used to supplement the x-ray radiography. A sample in which x-ray radiography showed little die attach voiding had significant die attach disbonds at both the die/die attach interface as well as the die attach/substrate interface. The disbonds were identified by the acoustic microscope. Interpretation of the acoustic microscopy data proved complex and required careful comparison of the C-mode images generated with the A-scans at specific locations. The nature of the disbonds at the A-scan locations was confirmed using dye penetrant testing, metallurgical cross section and optical microscopy. The disbonded areas can change the thermal dissipation characteristics and mechanical stress distribution of the sample and indicate processing problems. X-ray radiography is effective for determining density variations or voiding in the die attach and acoustic microscopy is effective for determining interface characteristics and the combination of the two techniques provides an excellent approach for evaluating die attach in MCM’s. These techniques can be applied to interfacial analysis of other structures and can be used to characterize interfaces for modeling and establish evaluation criteria for non-destructive process monitoring.
A Model for Predicting the Precipitation Strengthening Response of Precipitation Hardened Alloys Strengthened by Ordered Precipitates
Authors: Fragomeni James M. , Hillberry Ben M. 
Published: March 2022

Abstract
A model was developed for predicting the precipitation hardening response of a particle strengthened alloy determined from the microstructure, composition, and heat treatment. The precipitates in the microstructure which impede dislocation motion and control the precipitation strengthening response as a function of the aging practice were used as the basis for determining the strength depending on the actual size distribution of particles. The particle size and distribution were determined from the microstructure via the heat treatment and composition. Consequently a micromechanical model was determined for predicting the variation in yield strength with aging time, temperature, and composition. The overall micromechanical model which was determined from the particle coarsening kinetics, dislocation mechanics, thermodynamics, resolved shear strength, as well as the particle strengthening mechanisms based on the dislocation particle shearing and dislocation particle looping interaction mechanisms was used to predict the strength of the demonstration alloy based on the microstructure. The demonstration alloy selected as the vehicle to model the precipitation strengthening response was a particle strengthened aluminum-lithium-zirconium alloy. Using this demonstration alloy, the overall model predicted from the microstructure the variation in strength with aging time, aging temperature, and composition, in the underaged, peak-aged, and overaged heat-treatments. The predicted aging curves were in good agreement with the experimental results for different aging practices.
Study on Robust Fail-Safe Structural Design Method
Authors: Hiroyasu Tomoyuki , Shoji Maho , Yamakawa Hiroshi 
Published: March 2022

Abstract
The designs of structures, such as bodies of cars, hulls of ships, and frames of buildings, can be roughly divided into two flows: those are the upper flow and the lower flow of the design process. In this study, the new structural design method called “Robust Fail-safe Structural Design Method” is proposed for structures that are designed in the upper flow of the design process. By this method, the Young’s modulus and the topology of the structures are determined simultaneously. The designed structures also have the characteristics of robustness and fail-safe. The numerical example is shown to demonstrate to design a structure by this method. In the numerical example, some candidates of the robust fail-safe structures are derived and the problems are discussed.