bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wafer Level Underfill Processing
Authors: Nguyen Luu , Quentin Christopher , Nguyen Phuong 
Published: November 2021

Abstract
Underfill materials play a major role in the reliability of flip chip packages. These adhesives have been the subject of much research and development in the last few years, and much improvement in material performance has been obtained. However, the assembly method still remains unchanged, with the underfill being dispensed at the individual die level after flip chip reflow. Even with the arrival of “no-flow” underfills, assembly still requires depositing the underfill material onto the flip chip site prior to positioning the flip chip die. Processing underfill at the wafer level brings in a new paradigm shift to the area of flip chip packaging. Precoating the wafer with the underfill will create significant savings in both time and money. The application cycle time of the wafer level process becomes equivalent to a single dispensing operation for all the good dies on the wafer.
This paper will present results obtained with screen printing used as the application method for the wafer level process. An experimental underfill was printed onto un-bumped silicon wafers and cured, and the resultant films were analyzed. Process conditions affecting film thickness and surface roughness were evaluated. Preliminary results with bumped wafers are also discussed.
Parametric Design and Reliability Analysis of WIT Wafer Level Packaging
Authors: Lin Y. T. , Tang P. J. , Chiang K. N. 
Published: November 2021

Abstract
The demands of electronic packages toward lower profile, lighter weight, and higher density of I/O lead to rapid expansion in the field of flip chip, chip scale package (CSP) and wafer level packaging (WLP) technologies. The urgent needs of high I/O density and good reliability characteristic lead to the evolution of the ultra high-density type of non-solder interconnection such as the wire interconnect technology (WIT). The new technology using copper posts to replace the solder bumps as interconnections shown a great improvement in the reliability life. Moreover, this type of wafer level package could achieve higher I/O density, as well as ultra fine pitch. This research will focus on the reliability analysis of the WIT package structures in material selection and structural design, etc. This research will use finite element method to analyze the physical behavior of packaging structures under thermal cycling condition to compare the reliability characteristics of conventional wafer level package and WIT packages. Parametric studies of specific parameters will be performed, and the plastic and temperature dependent material properties will be applied to all of the models.
Micro-Mechanics of Creep-Fatigue Damage in Pb-Sn Solder Due to Thermal Cycling
Authors: Sharma Pradeep , Dasgupta Abhijit 
Published: November 2021

Abstract
This paper presents a micro-mechanistic approach for modeling fatigue damage initiation due to cyclic creep in eutectic Pb-Sn solder. Damage mechanics due to cyclic creep is modeled with void nucleation, void growth and void coalescence model based on micro-structural stress fields. Micro-structural stress states are estimated under viscoplastic phenomena like grain boundary sliding and its blocking at 2nd phase particles, and diffusional creep relaxation. A conceptual framework is provided to quantify the creep-fatigue damage due to thermo-mechanical cycling. Some parametric studies are provided to better illustrate the utility of the developed model.
Applications of World Wide Web in Teaching Large Scale Machinery Diagnostics
Authors: Shoureshi Rahmat , Terry Benjamin 
Published: November 2021

Abstract
As industrial competition intensifies, more emphasis is placed on increased productivity and reduction of cost. In every industry, a major component of manufacturing cost is associated with operation and maintenance expenses. Thus, there has been a significant interest expressed by industry in the development of means and methodologies for the reduction of operation and maintenance expenses.
Unfortunately, most engineering students go through an engineering curriculum that does not contain any formal courses or training on monitoring and diagnostics. Issues such as cost of operation, technical manpower, maintenance, safety, availability of space, etc. are examples of important factors that prevent universities from establishing such facilities.
This paper presents a new concept that overcomes such barriers and difficulties and introduces an engineering health monitoring and diagnostic curriculum by means of an integrated effort between academia and industry. The resulting real and virtual experimental facilities and curriculum in the area of health monitoring and on-line diagnostics are presented and described.
An Apparatus for Visualizing Frequency Response
Authors: Layton Richard A. , Pai Devdas 
Published: November 2021

Abstract
A second-order, mass-spring-damper apparatus was developed to help students visualize amplification, resonance, attenuation, and phase angle in mechanical systems. The apparatus was developed as a design project involving both graduate and undergraduate students. A prototype of the apparatus is complete and work is underway to correct design deficiencies and produce an improved apparatus. This paper describes the work in progress to develop a final apparatus for student use.
Signal Distortion Compensation of Linear Time-Invariant Measurement System
Authors: Wang Changting , Gao Robert X. 
Published: November 2021

Abstract
Non-distortion is an important aspect in precision measurement, calibration and signal processing. In this paper, the distortion error of a linear time-invariant measurement system is derived for periodical and non-periodical signal inputs, using Fourier Series and Fourier Transformation. The signal distortion is measured by the error-to-signal energy ratio. A charge amplifier circuit has been analyzed as an example, which shows that the distortion of an LTI system can not be simply neglected if precision measurement is required. Direct compensation and adaptive control methods have been discussed to reduce the LTI system distortion. The applications of these two methods to the charge amplifier design are discussed, which demonstrated good results.
A Simple Method for In Situ Determination of Linear Thermal Expansion Coefficients of Thin Films
Authors: Pan Chi Hsiang 
Published: November 2021

Abstract
This work presents a simple method for determination of linear thermal expansion coefficients (LTEC) of thin films with a compact microstructure. The microstructure comprises of a pair of cantilever beams with different lengths connected by a short tip. By heating the microstructure, the thermal strain causes two beams to deflect each other, thereby magnifying the deflection, which is measured by the tip directly under an optical microscope with the specimen placed in a heating stage. An analytical model is derived to relate the measured displacement to thermal strain, therefore, LTEC of thin films can be calculated. The analytical model is free from any correction factor. Furthermore, the accuracy of LTEC measurement is significantly enhanced because the measured displacement is independent of some physical values, namely the Young’s modulus, Poisson’s ratios and thickness of the substrate and the thin film, and the LTEC of the substrate. Finite element model is also used to support the analytical model and to perform nonlinear analysis. Experimental results with SiO2 films as well as undoped LPCVD polysilicon films are used herein to demonstrate the effectiveness of the proposed method.
Cartesian Versus Joint Space Command Shaping for a Ship Boom Crane
Authors: Agostini Michael J. , Parker Gordon G. , Groom Kenneth , Robinett Rush D. , Leban Frank 
Published: November 2021

Abstract
This paper presents a command shaping control method for suppressing operator induced payload swing in rotary, ship-based, boom cranes. The crane configuration studied consists of a payload mass that swings on the end of a spherical pendulum of varying lift-line length (hoisting). The lift-line is attached to a boom capable of elevation (luffing). The boom can rotate about an axis perpendicular to the ship’s deck (slewing). Positioning of the payload is accomplished through luff, slew, and hoist commands issued in real-time by an operator. A Cartesian space command shaping method is developed and compared to a previously documented joint space approach. Although both methods are appropriate for low rate crane maneuvers, the Cartesian method provides better performance under the tested operating conditions. Simulation results are presented to compare their performance.
Development of a Vision Based Orientation Sensor
Authors: Garner Harry , Lee Kok-Meng 
Published: November 2021

Abstract
The development of a vision based orientation sensor for the measurement of the orientation of a spherical body is presented. A specially designed grid pattern used to encode absolute orientation information onto a spherical surface in terms of latitude and longitude angles is discussed. A novel algorithm for the analysis of images of this grid pattern based on tracking along the grid lines is also developed that is designed to overcome limitations of other traditional image analysis techniques in terms of speed and accuracy. A procedure for recovering the absolute orientation of a spherical surface encoded with the special grid pattern using the line tracking algorithm, camera calibration, and Horn’s (1987) technique is also presented. Finally, experimental results of this procedure applied to a sequence of images are presented and discussed.
Experimental Study of a Neural Generalized Predictive Force Control for a Hydraulic Actuator
Authors: He S. , Sepehri N. 
Published: November 2021

Abstract
In this paper, multilayer feedforward neural networks (NNs) are used for modeling and force control of a hydraulic actuator. The predictability of the instantaneous linearized neural model is examined and is used along with the generalized predictive control (GPC) algorithm to control the force exerted on the environment. Experimental results show that the neural-based generalized predictive control can handle different contact environments despite high nonlinearity and uncertainty in the hydraulic functions.
A New Control Approach to Nonlinear Systems Undergoing Changes in a System Parameter
Authors: Nho Hyuk C. , Meckl Peter 
Published: November 2021

Abstract
Conventional model-based computed torque control fails to produce good trajectory tracking performance in the presence of payload uncertainty and modeling error. The problem is how to provide accurate dynamics information to the controller. A new control architecture that incorporates a neural network, fuzzy logic and a simple proportional-derivative (PD) controller is proposed to control an articulated robot carrying a variable payload. A feedforward (multilayer) neural network is trained off-line to capture the nonlinear inverse dynamics of the system. The network is placed in the feedforward path to minimize tracking error. The network receives the same input signals as conventional computed torque as well as the payload mass estimate, which comes from a fuzzy logic mass estimator. The fuzzy logic, trained off-line to optimize the membership function, is developed to estimate the changing payload mass. The fuzzy logic estimator is based on joint acceleration error to improve the speed of detection and estimation of payload mass change. The effectiveness of the proposed architecture is demonstrated by experiment on a two-link planar manipulator with changing payload mass. Experiment results show that this control architecture achieves excellent tracking performance in the presence of payload uncertainty. The results of the control architecture are also compared with those of a model-based control architecture. This approach can be employed in any nonlinear mechanical system with a sudden change in a parameter.
Aggregation of a Class of Large-Scale, Interconnected, Nonlinear Dynamical Systems
Authors: Darbha Swaroop , Rajagopal K. R. 
Published: November 2021

Abstract
In a previous paper, we discussed the characteristics of a “meaningful” average of a collection of dynamical systems, and introduced as well as contructed a “meaningful” average that is not usually what is meant by an “ensemble” average. We also addressed the associated issue of the existence and construction of such an average for a class of interconnected, linear, time invariant dynamical systems. In this paper, we consider the issue of the construction of a meaningful average for a collection of a class of nonlinear dynamical systems. The construction of the meaningful average will involve integrating a nonlinear differential equation, of the same order as that of any member of the systems in the collection. Such an “average” dynamical system is not only attractive from a computational perspective, but also represents the macroscopic behavior of the interconnected dynamical systems. An average dynamical system can be used in the analysis and design of hierarchical systems.
H∞ Synthesis of Nonlinear Feedback Systems in a Volterra Representation
Authors: Glass John W. , Franchek Matthew A. 
Published: November 2021

Abstract
Presented in this paper is a procedure for selecting the H∞ performance weights for a class of nonlinear feedback systems modeled by a truncated Volterra series. The performance weight selection addresses the trade-offs between closed loop performance and closed loop stability. The class of feedback systems consider regulating systems subject to step disturbances. The methodology is based on two recent results concerning closed loop stability for this class of nonlinear feedback systems [1]. These stability conditions can be formulated as an H∞ problem where the performance weights are systematically identified. This proposed synthesis procedure is applied to the idle speed control of a Ford 4.6L V-8 fuel injection engine. Through this application, the design trade-off between closed loop performance and stability is illustrated. A performance trade-off curve is then used to synthesize controller for the regulation system.
Power Feedback Control in Cylindrical Traverse Grinding
Authors: Hecker Rogelio L. , Liang Steven Y. 
Published: November 2021

Abstract
This paper describes the design of a power controller in cylindrical traverse grinding (CTG), where the power consumed by the grinding wheel is controlled by regulation of the traverse velocity.
A mathematical model relating the power to the traverse velocity was developed and quantified with machining data. The controller design was based on the power-velocity model developed and it was tuned to fulfill time response specifications including settling time and overshoot. An inner velocity loop was also designed and implemented inside the power close loop to guaranty a stable power response.
The controller was implemented and tested on an open architecture cylindrical grinding machine. The results show that the controlled system response can be regulated to meet the requirements of time specifications, over a wide range of cutting depth and input power reference.
Open Systems Formulation and Gaining Insight Using Lagrangian Bond Graphs
Authors: Redfield Robin C. 
Published: November 2021

Abstract
Models of a small-scale water rocket are developed as an example of open system modeling by both the bond graph approach and a more classical method. One goal of the development is to determine the benefits of the bond graph approach into affording insight into the system dynamics. Both modeling approaches yield equivalent differential equations as they should, while the bond graph approach yields significantly more insight into the system dynamics. If a modeling goal is to simply find the system equations and predict behavior, the classical approach may be more expeditious. If insight and ease of model modification are desired, the bond graph technique is probably the better choice. But then you have to learn it!
Design of Compliant Mechanical Amplifiers for Piezoceramic Stack Actuators Considering Stiffness Properties
Authors: Frecker Mary , Canfield Shawn 
Published: November 2021

Abstract
A topology optimization method for design of compliant mechanical amplifiers for piezoceramic stack actuators is presented. Previously the optimization was done assuming that the stack actuator provided a constant unit load to the compliant mechanism. However, it is well known that the best actuator performance occurs when the stiffness of the stack is considered and matches the stiffness of the surrounding coupling structure. In this paper an improved formulation is presented where the piezoelectric properties and stiffness of the stack are included along with an external spring representing a resisting load the actuator is working against. The optimization problem formulation, finite element implementation, solution algorithm are discussed. Two design examples are presented which illustrate the effect of the stiffness of the external spring and the size of the design domain on the topology of the solution.
Piezo Driven Mechanisms With Flexural Joints
Authors: Koster M. P. 
Published: November 2021

Abstract
The properties of flexures and piezo actuators in mechanisms perfectly fit. Piezo actuators in general are applied where accuracy is emphasized. Flexural joints take care that high accuracy is maintained throughout the mechanism. Flexures are known to have their limitations in terms of rotation and displacement. Piezo actuators generate relatively small displacements. Despite the limitations of fexible joints and of piezo actuators, piezo driven, flexural mechanisms were realized, capable of large displacements and high accuracy.
A Mesoscale Mechanism for Adaptive Mobile Manipulation
Authors: Voyles Richard M. 
Published: November 2021

Abstract
A novel, centimeter-scale crawling robot is described. Intended for military and civilian surveillance and search-and-rescue applications, the robot must be small, rugged, and lightweight with robust, reconfigurable capabilities. As a result, a dual-use design employing two arms for both manipulation and locomotion was conceived. The robot consists of two, three-degree-of-freedom arms that can stow completely inside the 75 mm diameter cylindrical body for ballistic deployment. This paper describes the mechanism and design motivation as well as three novel locomotion gaits and a fourth conventional gait. An outline for gait adaptation is suggested for future work.
The Effects of Real and Computer Generated Friction on Human Performance in a Targeting Task
Authors: Richard Christopher , Cutkosky Mark 
Published: November 2021

Abstract
We present the results of haptic interaction with real and virtual Coulomb friction. Tests were conducted to explore the effects of various types of friction on human performance in a Fitts-style targeting task. The results indicate that haptically rendered friction affects subject performance in a manner quite similar to that of real physical friction. Furthermore, moderate low-stiction friction tends to improve subject performance both in terms of speed and accuracy. High-stiction friction, however, degrades subjects performance, especially in terms of speed.
Analysis of Bonded Shrink Fitted Joints Under Push-Off Forces: The Effect of Joint Size on the Joint Strength
Authors: Sawa Toshiyuki , Yoneno Masahiro , Matsunami Yasuo 
Published: November 2021

Abstract
Shrink fitted joints have been widely used in mechanical structures. Recently, joints combining shrink fitted with an anaerobic adhesive have been developed in order to increase the joint strength. This joint is named the bonded shrink fitted joint. In this paper, push-off tests were carried out to measure the joint strength of bonded shrink fitted joints. In addition, the strength of the shrink fitted joints without the anaerobic adhesive was also measured. In the experiments, the effect of shrinking allowance, the outer diameter of the shafts, and the engagement length on the joint strength are examined. In addition, the size effect of joints is also examined in the experiments taking into account the surface roughness, and the roundness. The stress distribution of the joints subjected to a push-off load is analyzed using axisymmetrical theory of elasticity as a four-body contact problem. Using the stress distribution, the joint strength is estimated. The experimental results are in a fairly good agreement with the numerical results. It is found that the push-off strength of the bonded shrink fitted joints is greater than that of the shrink fitted joint.
Ductile Damage Evolution Under Different Strain Rate Conditions
Authors: Bonora Nicola , Gentile Domenico , Milella Pietro Paolo , Newaz Golam , Iacoviello Francesco 
Published: November 2021

Abstract
Failure of ductile metals is always controlled at microstructural level by the formation and growth of microcavities that nucleate from inclusions embedded in the ductile matrix, also at high deformation rate. Many damage models have been proposed to describe both evolutions of these cavities under the action of increasing plastic deformation, and the associated effects on the material behavior. Basically, two classes of damage models are currently available: the Gurson’s type model and continuum damage mechanics (CDM). In the framework of CDM, Bonora (1997) proposed a non-linear damage model for ductile failure that overcome the main limitations presented by others formulations: the model is material independent and its validity under multiaxial state of stress conditions has been verified for a number of class of metals, (Bonora, 1998, Bonora and Newaz, 1997). In addition, this model has the main feature to require a limited number of physically based parameters that can be easily identified with ad hoc tensile tests. In this paper, for the first time, the effect of the strain rate on ductile damage evolution has been studied in a quantitative manner evaluating the material loss of stiffness under dynamic loading. Damage measurements on SA537 Cl 1 steel have been performed according to the multiple strain gauge technique on hourglass shaped rectangular tensile specimen. Dynamic effect was introduced performing the test at different imposed displacement rates. An extensive scanning electron microscopy analysis has been performed in order to correlate damage effects with the microstructure morphological modification as a function of the applied deformation rate.
Computational Approach for Adhesively Bonded Composite Joints
Authors: Anwar Iqbal , Newaz Golam 
Published: November 2021

Abstract
A computational intensive study was performed to assess an efficient way to model adhesively bonded glass fiber reinforced composite joints in automotive applications. Three different finite element modeling techniques had been implemented. First, adhesive was represented by 1D-spring elements. Spring stiffness was calculated from adhesive property. This model is inadequate to assess stresses developed in the adhesive layer directly. So adhesive was modeled with 2D elements for better assessment of state of stress in the adhesive and the substrate. Both the model provide limit load, but crack initiation and failure of the bond can not be captured. The third approach adopted was the nodal failure model. In the nodal failure model, to understand the failure of adhesively bonded joints, bond strength had been specified to the interface nodes of the composite substrate. Combined failure criteria had been used. Cracks propagated and interface debonded when interface stress exceeded the failure limit. Finite element model results compared well with the experimental data. This modeling approach was later adopted for dynamic modeling of adhesively bonded joints, which shows promise.