bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Analytical Estimate of Global CTE Mismatch Displacement in Areal-Array Solder Joints
Authors: Heinrich S. M. , Shakya S. , Lee P. S.
Published: July 2023

An analytical expression is derived for determining the maximum solder joint shearing displacement occurring in an areal-array interconnect under global CTE mismatch loading. The result may be viewed as a “load correction factor,” to be applied to the commonly used estimate which is based on the free thermal expansion of component and substrate. The new expression for the correction factor includes the following parameters: (a) dimensions and material properties of component and substrate, (b) array size and population, (c) material properties of solder, and (d) geometric parameters of the individual joints. The theoretical result is based on modeling the assembly as two circular elastic disks connected by a shear-type “elastic foundation” whose distributed shear stiffness is related to the joint/array characteristics. The analytical expression and the graphical aids presented herein may provide convenient alternatives to performing time-consuming and expensive finite element “macro-analyses” on the assembly for the purpose of specifying boundary conditions for a subsequent “micro-analysis” on a single joint.
Reversible Permeabilization of Plasma Membranes With Engineered Nano-Scale Switchable Pores
Authors: Russo Michael J. , Bayley Hagan , Toner Mehmet
Published: July 2023

By using an engineered, self-assembling, proteinaceous, nano-scale pore equipped with a metal-actuated switch, a technique to deliberately and reversibly permeabilize the plasma membrane to small molecules (∼1000 Da) has been developed. We have demonstrated the dose dependent permeabilization of fibroblasts by 2 nm pores designed to be blocked and unblocked by the addition and removal of μM concentrations of Zn2+. Further, we have shown that the activity of the switch allows permeabilized cells to maintain viability following unconstrained flux of small molecules. This ability to control the transmembrane influx and efflux of molecules and thereby vary the intracellular environment yet maintain cell viability will impact an array of biological and medical problems.
Development of a Noninvasive Blood Perfusion Probe
Authors: O’Reilly Thomas B. , Gonzales Terry L. , Diller Thomas E.
Published: July 2023

Development of a noninvasive biomedical probe for tissue blood perfusion measurements is described. Simultaneous measurements of the local temperature and heat flux during a thermal cooling event at the surface of the skin is used to determine blood perfusion in the underlying tissue. The probe incorporates a combination heat flux and temperature sensor, which is placed in contact with the tissue and cooled by jets of room temperature air. For safety reasons no electric power or heating is applied to the probe; its low level signals are generated by the small temperature difference produced by air cooling. The small, light-weight probe can be taped to the skin, much like a surface electrode, for repeated measurements.

A combination of analytical and experimental results are reported to describe the measurement system. The effect of thermal contact resistance between the probe and tissue is included in the model. Experimental results indicate good heat flux sensitivity and measurement repeatability. Comparison of analytical heat flux predictions and experimental measurements is good. Although not yet fully tested, this non-invasive technique has promise of providing quantitative blood perfusion measurements.
An Interferometer for Measuring the Surface Displacement of a Reflecting Biological Tissue Surface
Authors: Yablon Andrew D. , Nishioka Norman S. , Mikic Borivoje B. , Venugopalan Vasan
Published: July 2023

An interferometer capable of precise time-resolved monitoring of the surface displacement of biological tissue has been designed and built. This interferometer is particularly useful because it can work with both diffuse and specular surfaces. The device is a modified Mach-Zehnder interferometer employing a standard HeNe laser and monitors a 15 μm diameter region on the surface of the tissue target. The instrument rise time is typically 5 ns and the measurement duration is limited only by the number of data points stored. The interferometer can also determine the direction of target surface motion because the signal is modulated by a 110 MHz acousto-optical modulator (AOM). Surface displacement accuracy depends on surface quality but generally ranges from 1 to 10 nm for the samples tested. Composite two dimensional time-resolved surface maps are created by assembling data obtained from different positions on the surface during separate events. The interferometer has been successfully employed to track the surface motion of gelatin tissue phantoms, porcine reticular dermis, and bovine corneal stroma subjected to 20 ns ArF excimer laser pulses, 40 ns Q-switched Er:YSGG laser pulses, and 180 ns TEA CO2 laser pulses. The interferometer can provide information about the mechanical effects of pulsed laser irradiation of biological tissue and it may also have applications as a diagnostic tool if it can be shown to be sensitive to the mechanical properties of the target tissue.
Investigation of Bleed-and-Feed Procedures for Mitigating the Consequence of a Total Loss-of-Feedwater Transient: IIST Experiments
Authors: Lee C. H. , Liu T. J. , Chang C. Y. , Hong W. T. , Chan Y. K. , Hwang I. M. , Chang C. J.
Published: July 2023

A reduced-height and reduced-pressure (RHRP) INER (Institute of Nuclear Energy Research) Integral System Test (IIST) facility has been built for simulating the thermal hydraulics (T/H) behavior of Westinghouse three-loop pressurized water reactor (PWR). Experiments on loss of all feedwater (LOFW) with no operator action and with reactor coolant system (RCS) bleed and feed were conducted at the IIST facility. The experimental results not only explore the key (T/H) phenomena during LOFW transients but also show the validation of RCS bleed-and-feed procedures for mitigating the consequence of LOFW transient.
Rapid Response Manufacturing in Distributed Environments: The Important Roles of Process Planning and Open Architectures
Authors: Park Hisup , Stori James A. , Wright Paul K.
Published: July 2023

We focus on the “architecture” of a hardware and software test-bed for an integrated approach to rapid prototyping and rapid response manufacturing using conventional milling techniques. A central knowledge base is proposed that links the sub-systems and permits open, networked communication throughout the design to manufacture process. There are three essential steps for this to attain reality. First, we are developing a variety of solid object “features” that the designer can use to create components. Second, we are developing a process planning interface that initially advises the designer on the correctness of the design and then creates the necessary process plan. Third, we are developing the machining routines on an open-architecture machine tool that allow automatic component generation over the Internet. Videomanufacturing demonstrations have been carried out between the designer and the remote machines.
A Systems Approach for Simulation and Production Implementation of Thru-Feed Centerless Grinding of Ceramics
Authors: Gust Darryl J. , Shih Albert J. , Tricard Marc , Subramanian K.
Published: July 2023

An approach for simulation and production implementation of thru-feed centerless grinding of Transformation Toughened Zirconia ceramic using vitrified diamond grinding wheels is presented. A set of grinding tests was designed and conducted, to identify the effects of: abrasive product (diamond grit size, wheel bond type), work material type and operational factors (stock removal, thru-feed rate, number of thru-feed passes and truing and dressing methods); on grinding performance. Evaluation parameters of surface finish, grinding forces, wheel wear, and G ratio were utilized to determine machine tool features. Very fine surface finishes, in the 0.05 to 0.1 μm (2–4 μin) Ra range, could be achieved using vitrified bonded micro-grit diamond grinding wheels from grinding, without additional part processing. Such a level of surface finish on ground ceramics has traditionally been generated only by using resinoid bonded diamond wheels in batch production operation. These test results were used to design and manufacture a full-sized composite or sandwiched diamond grinding wheel, with three grades of abrasives. This grinding wheel has been successfully applied in high-volume ceramic production, which in turn has verified the proposed approach. Simultaneous and strategic consideration of these four input groups: machine tool, abrasive product, work material and operational factors is essential to achieve quantum improvements in production grinding processes. This system approach is briefly described and the results from such methodology are also noted in this paper.
A Step-Compatible Approach for IC Packaging Scheduling System
Authors: Liu Thu-Hua , Trappey Amy J. C. , Chan Fu-Wei
Published: July 2023

This research develops a Computer-Aided Scheduling System (CASS) for IC packaging industry. We adopt the concept and methods of STEP enabling technologies to model and implement the system. The effort aims to achieve integration of engineering applications by standardizing the modeling and the use of product data. This paper uses IDEFO to model the IC packaging scheduling process and, then, EXPRESS language to define the data models. The IC packaging scheduling system is implemented in an integrated environment using the object-oriented language (C++) and the object-oriented database (ObjectStore). The ST-Developer is used as the kernel to interface the application language, the database, and the EXPRESS data models. The architecture of this integrated implementation environment is not only effective for scheduling task but also useful in general applications for product design, analysis and production planning.
Step-Compatible PCB Assembly Data Model for Assembly Analysis
Authors: Trappey Amy J. C. , Hwang Chii-Tong , Liu Thu-Hua
Published: July 2023

This paper focuses on the data modeling of PCB assembly and its part definition, particularly for PCB assembly analysis. We first analyze the procedure of PCB assembly. The key processes, namely insertion and soldering, which are often considered critical in PCB assembly, are discussed. Then, the factors considered in assembly analysis are described. The data related to these factors are also depicted. Most importantly, this research develops a STEP-compatible data model to define data formats for assembly analysis, mainly PCB assembly data and component data. Implementation structure of the database using the defined data model is discussed. Finally, a PCB assembly example is used to describe the data model at work. This research provides a PCB data model, which is consistent with other STEP-based and STEP-compatible data models and can achieve the product data integration for concurrent engineering practice.
Development of Step-Based Dimensioning and Tolerancing Data Model
Authors: Tsai Jhy-Cherng , Chuang Tsan-Chao , Guo De-Ning
Published: July 2023

STEP product model is an effort to develop an international product modeling standard by the International Standards Organization (ISO). The product model involves both working standard and information models. As product accuracy becomes tighter, dimensioning and tolerancing (D&T) plays an important role in product lifecycle. It is an important issue to develop a D&T data model based on STEP. This paper describes the development of a STEP-based D&T data model. Required information to build a STEP-based D&T scheme is investigated. Implementation of such a data model and construction of a product D&T specifications based on the model are then described. Three examples, including a single part with an interface for tolerance analysis application and an assembled product, are used to illustrate the usage of the data model.
Pick-to-Light System Benefits: Productivity, Quality, Process Time
Authors: Sharp Gunter P.
Published: July 2023

Recent trends in order assembly (picking) reflect greater use of paper-less picking. Little systematic evidence exists on the advantages of this technology. This paper presents the results of a survey of ten pick-to-light systems, with respect to productivity improvements and reduction in errors (quality improvement). The systems, located in four countries, were surveyed during 1993–94. Both case picking and less-than-case picking were included in some systems.

Although some of the improvements are as expected, there are surprises. Further, justification of the systems often depended on more than the cost savings and quality improvements. In those situations where no quantification was possible, qualitative aspects of the technology still played an important role. The paper presents these issues and puts them in the perspective of today’s global logistics systems. The paper also presents some current research issues and future trends in the industry in the pick-to-light industry.
Elasto-Plastic Finite Element Analysis of Isotropic Plates With U-Notches
Authors: Arslan Nurettin , Turgut Aydın , Sancaktar Erol
Published: July 2023

Elasto-plastic stress analysis of the U-notched isotropic steel plates (SAE 1060) has been carried out using the finite element method (FEM) Isoparametric rectangular elements with four nodes have been employed and the Lagrange polynomial has been used as interpolation function Mechanical properties and yield strength of the U-notched plates have been obtained experimentally using a tensile testing machine. The spreads of the plastic zones have been illustrated for varies cases. Residual stress and equivalent stresses obtained have been presented in diagrams and compared with some of the relevant studies in the literature. The tensile loads of the isotropic plates with U-notches have been shown to increase due to residual stresses which take place under plane stress conditions.
A Curriculum for Engineering Systems
Authors: Shoureshi Rahmat A. , Gosink Joan P. , Middleton Nigel T.
Published: July 2023

The role of the engineer in society is rapidly changing. Advances in such areas as manufacturing, transportation, infrastructure systems, materials, communications, and high performance computing have introduced new demands, opportunities, and challenges for engineers. What was a solitary endeavor at a computer, a drafting table, or a work site, has become a team activity. Today’s industry requires engineers with diverse interdisciplinary skills, a total systems viewpoint, entrepreneurial acumen, and an understanding of global forces in the marketplace. Above all, today’s engineers are expected to support and enhance our way of life by synthesizing increasingly complex engineering systems using methods that are socially, economically, and environmentally responsible.
The Need for Versatility by Today’s Engineer in Dealing With Complex Engineering Systems
Authors: Rafanelli Anthony J.
Published: July 2023

The concept of teams is rapidly changing the way products are developed and produced today. With the onset of such philosophies as Total Quality Management (TQM) and Concurrent Engineering (CE), today’s engineer must learn backgrounds. Moreover, the trend of downsizing has resulted in less people doing more and, subsequently, learning many additional, as well as different, skills than one could ever have imagined.
Implementing Systems Engineering Into an Ongoing Program
Authors: Altomare Philip M.
Published: July 2023

Systems Engineering as a process for the management of large complex projects has been practiced for many years in the defense and aerospace industries. There, through experience of application, it has been developed into a standard process, or set of processes, depending on whether one is looking at the whole or its parts. The logic, and success, of the approach are such that it has been published in several standards, originally as Mil Std 499a and follow on Draft Mil Std 499b, and now as commercial standards EIA 632, and IEEE 1220. The process is now being adopted by some non-defense industries but it has not been generally recognized as a useful management tool for all types of projects, large or small, defense or non-defense. This may be due to its association with large complex Department of Defense or aerospace engineering projects, or difficulties encountered in attempting to apply the concepts. Systems engineering is a fundamental, simple process but may encounter difficult problems when implemented in large ongoing programs or projects. This paper discusses the problems and possible solutions for implementing systems engineering into ongoing programs or projects.
Extremely Large Scale Broadcast Facilities
Authors: Karam James T.
Published: July 2023

The advent of Direct Broadcast Satellites requires the associated development of origination facilities supporting hundreds of viewer channels. Such facilities use highly automated, fault tolerant control systems to facilitate cost-effective staffing levels and the flexibility to support services that are only now evolving.

We summarize the capabilities and architecture of two such facilities that are among the largest in the world: the more than 175 channel DIRECTV® Castle Rock Broadcast Center (CRBC) servicing the continental United States from Colorado, and the 72 channel DIRECTV International Inc. California Broadcast Center in Long Beach servicing Latin America and the Caribbean. For program transmission, these services use the latest, high-powered Hughes Kuband communication satellites. For program playback, each plant uses relatively conventional digital tape-based technology. Two factors make the program playout operations unique. First, their extreme size and scope. Second, all the resources in the plant are sharable and schedulable among different viewer channels to assure the plant can adapt to the services demanded by their evolving market. Some “lessons learned” are then discussed as suggestions to aid future product and facility developments.
The Role of Synthesis, Analysis, and Simulation in Engineering a Complex System: The Automotive Vehicle
Authors: Chang David C. , Rohde Steve M.
Published: July 2023

In this paper we define a “top down” systems engineering process that is driven by customer requirements, and which results in vehicle products that meet those requirements. This process is intended to effectively deal with the complexity of modern automotive systems. To implement the systems engineering paradigm, an approach that integrates functional product requirements with physical realizations, i.e., math-based synthesis is introduced. Synthesis and analysis are shown to be key to being able to define, design, and validate vehicles, vehicle subsystems and components, and processes to meet their physical and functional requirements simultaneously. This involves the utilization of mathematical models at a variety of levels of detail, and of multi-disciplinary computer based methods, e.g., computer-aided engineering (CAE). Examples of the application and benefits of the use of synthesis and analysis are shown throughout the automotive vehicle development process. The approach presented leads to shorter product development cycles at reduced cost, less prototype hardware builds, and superior quality and value for the customer.
Active Vibration Control Strategies on a Beam: Secondary Source Strength Requirements
Authors: Brennan M. J. , Elliott S. J. , Pinnington R. J.
Published: July 2023

In many of the active vibration control strategies that have been implemented on beams only one secondary source has been applied. If the control strategy is one of wave-suppression which is similar to that used in the control of acoustic waves in ducts, then the secondary source requirement can be very large at certain frequencies resulting in a significant increase in vibration upstream of the secondary source. This means that to implement a wave suppression control strategy over a range of frequencies then a large actuator is required. If more than one secondary source is applied then the required secondary source strengths are much diminished. This paper presents a theoretical and experimental study into the way in which the choice of control strategy and the number of actuators affects the actuator capacities required, which is important in the practical implementation of active control. A slender aluminium beam fitted with piezoelectric actuators is used for the experimental work, and predictions of secondary source requirements are made using measured data.
Two-Degree-of-Freedom Control System for Motion Control of Flexible Cartesian Robots
Authors: Sasaki Minoru , Okuda Kouji , Fujisawa Fumio , Okamoto Ryouichi
Published: July 2023

In this paper, a two-degree-of-freedom control system for motion control of a flexible cartesian robot is presented. The two-degree-of-freedom control system consists of a feedback controller and a feedforward controller. The feedback controller is designed based on Lyapunov’s direct method while the feedforward controller is designed based on the inverse system. A feedback control of the tip motion of a flexible system is derived by considering the time rate of change of the total energy of the system. The inverse system consists of finding the feedforward input that needs to be applied at base so that the end point of the arm can follow a desired trajectory. The simulation and experimental results verify that the proposed control system is effective at controlling the tip motion of the flexible cartesian robot.
Performance Limits of Shock Isolation Mounts for Specific Deterministic Inputs
Authors: Ferri Aldo A. , Eshleman Eric D.
Published: July 2023

This paper investigates the optimal isolation mount for specific deterministic inputs. Peak, rather than mean-squared, quantities are used as metrics of optimality. Both active and passive mounts are considered. Two design techniques are evaluated: direct minimization of a performance criterion and use of linear-quadratic-regulator theory. It is shown that for a variety of shock inputs, the optimal isolation mount is a purely passive, ideal friction element. However at times, the friction mount is suboptimal and active mounts are required to minimize the performance criterion.
Experimental Evaluation of Segmented Active Constrained Layer Damping Treatments
Authors: Kapadia Rajiv K. , Kawiecki Grzegorz
Published: July 2023

The objective of this research is to demonstrate the feasibility of segmented Active Constrained Layer Damping treatments to improve low frequency vibrations damping in flexible robotic arms. The Active Constrained Layer Damping treatment, under consideration, consists of a viscoelastic layer sandwiched between two piezoelectric layers. The shear deformation of the viscoelastic layer causes loss of energy and thus damping of vibration.

This paper focuses on the effects of constraining layer segmentation. Experimental results obtained for slender beams partially treated with segmented and unsegmented Active Constrained Layer Damping treatments are presented. Tested specimens have low natural frequencies, typical for flexible robotic manipulator arms. The performance of segmented and unsegmented treatments, as well as the performance of active and passive treatments is compared. Presented results demonstrate that significant improvement in Active Constrained layer treatment performance can be achieved by an appropriate segmentation of the constraining layer.
Smart Structure Technology for Rotor Blade Tip Clearance Control Using a Beam Model
Authors: Lin Y.-J. , Wen C. , Choi B. , Saravanos D.
Published: July 2023

This paper presents the experimental development of a simple and effective vibration control scheme by employing smart structure technology. Due to high accuracy and high slew rate requirements for lightweight structures, vibration control becomes a challenging task. In this paper, it is proposed to actively control rotor blade tip vibration with collocated piezoceramic sensors and actuators. To include the flexible characteristics of rotor blades in our analysis, a flexible cantilever beam is used to simulate the dynamic behavior of the cantilever beam due to external disturbances, generated by a magnetic shaker. The shaker was installed near the tip of the simulated rotor blade to maximize the external excitations. Piezoceramic sensor and actuator were used and evenly distributed as elements of the smart structure. The mathematical model of the smart structure including the piezoceramic sensors and actuators was determined by combining both analytical and experimental schemes. Based on the derived experimental dynamic model, a proportional gain feedback controller was implemented to compensate the vibratory deflections of the underlying structure. The results of the work show that the proposed control methodology along with the smart structure can suppress more than 80% of the measured structural vibration, which is considered satisfactory.
An Electrostatically-Driven Phase Change Actuator for Vibration Control
Authors: Hallinan Kevin P. , Kashani A. Reza , Bartsch Michael
Published: July 2023

Many motion control applications rely on piezoelectric and magnetostrictive type actuation devices to achieve active control or micro-manipulation. These devices have an important drawback. They are limited in their ability to simultaneously provide large force and large displacement.

A new concept electrostatically driven phase-change actuator (EDPA) has been theoretically studied to investigate if the drawbacks inherent to these devices might be overcome. This actuator concept relies upon changes in vapor pressure to expand a pliant membrane enclosing a vapor cavity. Changes in the vapor pressure are achieved by applying an electric field across a dielectric liquid film beneath the vapor space. The field polarizes the liquid molecules reducing the liquid pressure. A reduced liquid pressure produces an associated decrease in the equilibrium vapor pressure at the liquid-vapor interface. The surrounding vapor subsequently condenses causing a reduction in the vapor pressure. As a result, the membrane retracts. When the field is removed, the equilibrium vapor pressure increases above the pressure of the surrounding vapor, causing liquid to evaporate. The evaporation increases the vapor pressure, expanding the membrane.

Simulations of the device performance have shown it capable of producing forces of over 300 N with displacements of up to millimeters and sub-millisecond response time, while maintaining a much smaller package (lengthwise) than possible using stacked magnetostrictive or piezoelectric actuators. However, the transverse dimensions required to produce this force were found to be substantial (20 mm).
Discrete Domain Analysis of Delayed Resonator
Authors: Elmali Hakan , Olgac Nejat
Published: July 2023

The Delayed Resonator (DR) is a new active vibration absorption technique which uses time delayed partial state feedback to generate ideal resonance on a passive vibration absorber. It has many attractive features such as real-time tunability, ease of implementation and total suppression of vibration for tonal frequency disturbances. The DR controller has been developed in continuous domain until now. In this paper discrete domain analysis is presented. Simulation results indicate an expected dependency of stability on the sampling period for this active control strategy. A major advantage of discrete domain analysis is the reduction of characteristic roots from infinite to finite numbers and consequent simplicity in the analysis and design of the controller. It is shown that discrete domain control design for DR yields better vibration suppression considering the sampled control structure in implementations.
Active Structure Vibration Control Using Dynamic Neural Networks: Modeling Error, Nonlinear, Parameter Imprecise and Disturbance
Authors: Lu Zheng , Shi Xizhi , Wang Xuejun , Xu Min
Published: July 2023

In structure vibration control. Most of the results in the past time are based on idealized system description. Structural nonlinearities, modeling error, parameter imprecise and disturbance are four problems which are not solved completely till now. This paper uses a new type of dynamic neural network to control structure vibration. Singular perturbation theory is used and a neurocomputing approach is developed to solve these problems at the same time. Simulation results show that this new method can solve four problems in vibration control to some extent.
Investigation on Decreasing Combustion Noise of D.I. Diesel Engines
Authors: Yuan Xue , Shao-Xi Shi
Published: July 2023

Based on the theory analysis and multi-points measurement of combustion pressure oscillation in D.I. diesel engines, each resonance modes of combustion pressure oscillation are discussed. In the paper, the influence of pressure oscillation on combustion noise is analyzed. The methods of decreasing combustion noise through reducing pressure oscillation are investigated. Resarch results show that combustion noise can be decreased and economy can be improved when some parameters of injection system in D.I.diesel engines are changed.
Fuzzy Logic Identification of Ship Motions in Response to Varying Wave Incidence
Authors: Moore Christopher T. , Telionis Demetri P.
Published: July 2023

A fuzzy logic identification code was prepared. The program was trained with experimental data of pitch and roll of a ship model at various incidences to oncoming waves. The program can then predict the response of the model to any wave and at any incidence.
Development of a Particle-Fluid Model for Transient Analysis of Bubbly Two-Phase Flows in Parallel Channels
Authors: Pokharna H. , Mori M. , Ransom V. H.
Published: July 2023

Particle Fluid Model (PFM) is an intermediate method between the numerically intractable local instant model and the fully averaged two-fluid model for simulating transient two-phase flows. PFM uses a Lagrangian description for the dispersed phase and an Eulerian description for the continuous phase. In this paper an extension of the PFM to multiple channels with merging and branching is reported. As the treatment for boundary conditions for the discrete phase requires the use of an extra cell (ghost cell) at each end of the flow passage, the linking of boundary conditions becomes complicated. This linking process is established by overlapping the ghost cell of a channel with the first real cell of the next channel. Work is currently in progress to model parallel bubbly slug two phase flows merging into a single plenum.
The Influence of Heat Transfer on Two-Phase Flow Behavior During Pipeline Blowdown
Authors: Fairuzov Yuri V. , Erosa Jorge A. , Rosas M. Armando
Published: July 2023

The purpose of this study is to investigate the effect of heat transfer, between the fluid and the pipe wall, on the two-phase flow behavior during the blowdown of a long transmission pipeline. A mathematical model which describes transient two-phase flow and heat transfer in the pipeline was developed. A complete break of a long pipeline containing propane was simulated and ‘hree blowdown conditions were considered. These include (1) the fluid flow is adiabatic, (2) the pipeline is adiabatic, and (3) the pipeline interchanges heat with the surroundings. The model predictions were compared with limited available experimental data. The study revealed that the thermal capacitance of the pipe may have a significant influence on the two-phase flow behavior in the final stage of the blowdown.
Internal Flows by MOC: The Role of Friction
Authors: Wylie E. Benjamin
Published: July 2023

Rapidly-varying unsteady internal flows are commonly analyzed with great success using the method of characteristics. Numerical results are seldom questioned, although there are examples when the accuracy should be challenged. In this study the equations and exciter behavior are non-dimensionalized to provide a unified treatment of a class of problems. This permits statements to be made regarding accuracy and range of validity of a standard solution procedure.
Correlation of Loss Coefficients for 3D Separated Flow Through a Grille
Authors: Smith Brian , Birkett Craig A. , Shack David
Published: July 2023

A study was performed to calculate the loss coefficients for flow through thin grille shapes of various geometries. The grille shapes were stamped sheet sections with holes which caused highly separated flow when flow was applied normal to the surface. Two-dimensional and three-dimensional CFD models were first built of simple shapes and compared with known data. This provided information on mesh density and solution methods required to achieve accurate results. Next, symmetric models were built of a number of grille shapes. Loss coefficients were calculated for several Reynold’s numbers. As expected, loss coefficients were relatively independent of Reynold’s numbers. It was also found that loss coefficients depended to a large degree only on the percent area open to the flow. Thus it was possible to use a single curve to represent losses through the grille for a wide variety of shapes and air speeds. Experimental data were obtained in a wind tunnel for a subset of grille shapes. These results agreed well with the analytical solution.
Spectral Element Calculation of a Von Karman Vortex Street
Authors: Springer Marlow E.
Published: July 2023

This paper presents results for the direct numerical simulation of unsteady two-dimensional incompressible flow past a circular cylinder at a Reynolds number of 140. Conforming and nonconforming formulations of the spectral element method have been employed to compare the grid resolution reqirements for the von Karman vortex street. Results presented include the shedding frequenies, vorticity distributions, drag coefficients, and lift coefficients. Quantitative results published by others from experiments at the Reynolds number of interest were found for the shedding frequencies and drag coefficients. Results presented here are within five percent of published values for the shedding frequency and three percent for the drag coefficient. Qualitative comparisons for the vorticity distributions are made with published flow visualizations.
CFD Simulations in the Design and Evaluation of Heat Sinks
Authors: Nakayama W. , Behnia M.
Published: July 2023

The roles of CFD simulations in the design of heat sinks are discussed drawing two examples, one is the plate-fin array cooled by planar impinging air flow, and the other is the grooved heat transfer surface of a simulated chip cooled by dielectric coolant. In both examples the CFD analysis is performed to clarify the details of coolant flow and heat transfer in narrow channels which are difficult to capture by experimantal means. The experiments, which were conducted in parallel with the CFD analyses, provide the benchmarks for the CFD. It is emphasized that, in an endeavor to develop thermal design codes, the CFD simulation and the experiment are complementary to each other.
Offset Crush Analysis and its Applications
Authors: Mahmood Hikmat F. , Wheatley Donald , El-Hor Hassan H. , Hammoud Hassen
Published: July 2023

Until recently, frontal crash analysis and tests were performed to predict the performance and behavior of cars to meet full frontal crash safety requirements. Little has been done so far to control the energy absorption during an offset frontal crash. This topic has become a very interesting and challenging issue since it will be included in the federal regulations in the coming years.

In offset crash, the load is applied to one side of the front end, leaving the other side partially unloaded. In light of this situation, cross-members have to be carefully designed in order to absorb and safely transmit part of the offset crash load to the opposite side.

This paper will describe the theoretical performance of the front structure under an offset crash and at the same time identify all related parameters that influence this behavior. A computerized analysis of the single, full and offset crash will be performed and results and comparisons will be tabulated and graphed.
Comparison of Different Material Models in Simulating Compression and Energy Absorption of Bumper Foam During Low Speed Impact
Authors: Chen Ping , Alavandi Bhimaraddi , Saha Nripen K.
Published: July 2023

In this paper an analytical modeling of foam material using four different formulations is considered. Four material models considered here (MATERIAL LAWS 10, 21, 28 and 35) are available in RADIOSS (commercial non-linear finite element analysis code). All four models are used in simulating the deformation of structures consisting of foam components. Static compression test data, on foam cube samples of different densities, are first validated to arrive at the material parameters required as input to RADIOSS. Then, an application of foam material in an energy absorbing front bumper structure is studied. Comparison of these material models in low speed impact testing is carried out. Based upon the experience gained on material modeling of foam. Material Law 10 or 28 (preferably 28) is recommended to simulate low speed impact testing.
A Micro/Macro Solidification Model for Columnar Eutectic Alloys With Velocity-Dependent Freezing Temperatures
Authors: Judson Ward M. , Paolucci Samuel
Published: July 2023

A general multidimensional model for a solidifying columnar eutectic alloy is presented in which a velocity-dependent freezing temperature is coupled with the macroscale energy equation. At solidification rates (∼ 1–10 mm/s) that are representative of gravity permanent mold and die casting processes, near-eutectic alloys freeze with a macroscopically discrete solid-liquid interface at a temperature below the equilibrium eutectic temperature which can impact the heat transfer process.

The model is illustrated with one-dimensional solidification in a finite domain and solved numerically with a Galerkin finite element method. By nondimensionalizing the governing equations the effect of coupled eutectic growth on heat transport is clearly identified so that the model’s sensitivity to important parameters can be investigated. Additionally, the average eutectic spacing can be determined with the temperature field, rather than post-determination from a standard, uncoupled solution of the energy equation. The eutectic coupling results indicate that the eutectic interface location lags behind the uncoupled solution; therefore, decreasing the amount of solid formed, increasing the total solidification time, and increasing the average eutectic spacing.
On the Prediction of Weld Pool Size and Heat Affected Zone in Shallow-Pool Welding
Authors: Bos Jeannine A. , Chen Michael M.
Published: July 2023

Numerical modeling of the Weld pool has been pursued by many investigators over the last decade. Most of these efforts have focused on the details of fluid flow and heat transfer in the weld pool. These efforts have not addressed the important practical issues of the welding engineer which include reliable prediction of the weld pool dimensions and the size of the heat affected zone based on welding parameters such as power and speed. A consequence of this is that available prediction methods are still based on heat conduction considerations without any input from weld pool convection analysis. In the present paper it is shown that the dependence of weld dimensions on power and speed are relatively insensitive to the details of the flow and are primarily influenced by the aspect ratio of the weld pool. It is possible to divide the prediction of weld dimensions into two separate tasks. One task is the prediction of the pool aspect ratio. This is the role of weld pool convection studies. The other is the prediction of weld dimensions based on given aspect ratios and welding parameters. This is accomplished through heat conduction analysis outside the weld pool. Numerical computations for the latter have been carried out and the results are presented in correlations which are convenient for prediction purposes. Sample calculations to illustrate the use of the results are also given.
Magnetic Field Effects on a Laterally Vibrating Magnetic Liquid Column
Authors: Ohaba M. , Saito S. , Sudo S. , Sawada T. , Tanahashi T.
Published: July 2023

The magnetic field effects on both the static stability limit and the resonance frequency of a magnetic liquid column are examined theoretically and experimentally. We first derived the theoretical resonance frequency of a column using linear potential theory. Then, in the experiment, a vertical cylindrical magnetic liquid column was formed between two electromagnets. As the magnetic field intensity was decreased, the column’s diameter exhibited hysteresis, such that its stability limit extended to a smaller diameter range due to the coaxial magnetic field. The column was also subjected to lateral excitation and the surface frequency response of the non-axisymmetric first two modes were observed. It was found that the resonance frequency of the column increases with increasing magnetic field intensity and decreases with an increase in the aspect ratio of the column (mean diameter / height). The resonance frequency of the first mode was in qualitative agreement with the theory.
Semiconductor Deposition Profile Simulation Using Direct Simulation Monte Carlo Method
Authors: Ikegawa Masato , Kobayashi Jun’ichi , Maruko Morihisa
Published: July 2023

As integrated circuits are advancing towards smaller device features, step-coverage in submicron trenches and holes in thin film deposition is becoming concern. Deposition consists of gas flow in the vapor phase and film growth in the solid phase. A deposition profile simulator using the direct simulation Monte Carlo method has been developed to investigate deposition profile characteristics on small trenches which have nearly the same dimension as the mean free path of molecules. This simulator can be applied to several deposition processes such as sputter deposition, and atmospheric- or low-pressure chemical vapor deposition. In case of low-pressure processes such as sputter deposition, upstream boundary conditions of the trenches can be calculated by means of rarefied gas flow analysis in the reactor. The effects of upstream boundary conditions, molecular collisions, sticking coefficients and surface migration on deposition profiles in the trenches were clarified.
Modeling of Multiphase Transport During Solidification of Metal-Matrix Particulate Composites
Authors: Feller Robert J. , Beckermann Christoph
Published: July 2023

A multiphase model for the solidification of metal-matrix particulate composites is developed that accounts for macroscopic particle segregation due to liquid-particle flow and particle-solid interactions. Macroscopic transport equations are written for each phase with unknown parameters modeled through supplementary relations pertinent to the solidification of a binary alloy containing a stationary solid phase and generally non-stationary spherical particles. Model validation is performed through comparison of one-dimensional simulation results to experimental sedimentation and composite solidification results in which good agreement is found. One-dimensional case studies demonstrate the effect of cooling rate and direction, particle packing, clustering, and particle rejection on the final particle distribution in various Al-Si/SiC castings.
Flat Heads for High-Speed, Contact Tape Recording: Experimental Evaluation and Theoretical Analysis
Authors: Müftü Sinan , Hinteregger Hans F.
Published: July 2023

We report on an investigation of the mechanics and tribology of a flat head for high-speed, contact tape recording. We found that a self-acting negative air-bearing (suction) created near the leading wrapped corner is responsible for stable low-pressure contact over a wide range of speed, wrap angle, tension and tape thickness. This suction is caused by the expansion of air into the diverging gap on the upstream side of the head-tape interface which is unique to this wrap geometry. Experiments performed on a “row-bar” of thin film disk heads where the tape is wrapped only on the edge opposite to the heads showed the gap spacing to be stable in the 0.5–8m/s speed range with less than 4nm of wear on the read elements. A bi-directional version of a flat head geometry is analyzed via a model and suggestions are made for that design.
Optimization of Pole and Slot Widths for Reluctance Torque Reduction in a Brushless DC Spindle Motor
Authors: Chuang T. Y. , Lieu D. K. , McAllister J. S.
Published: July 2023

A parametric study was conducted to determine the effect of motor stator slot widths and rotor permanent magnet pole separation widths on the reluctance torque. This study is based on a finite element analysis of a particular 6-pole/9-slot motor. The analysis can be expanded to other slot/pole combinations. Force and torque calculations were based on an integration of the Maxwell stresses along the center of the airgap. As a general rule, the reluctance torque may be reduced by decreasing the slot width for any given pole separation. For any given slot width, the reluctance torque can be reduced to zero by selection of the proper pole separation. The optimum slot widths are slightly different than those predicted by past analytical formulation. There will be, however, a noticeable effect on the main drive torque and the torque ripple.
Body Height Change From Motor Vehicle Vibration
Authors: Hampel Gary A. , Chang Wen-Ruey
Published: July 2023

Subjects, are exposed to tri-axial whole body vibration for three hours, and measured periodically for height changes. The control was no vibration. A broad band predominantly 2 Hz Z-axis acceleration (mean 0.88ms−2) was input by a truck tractor driven on secondary roads. Effects on subject height from vibration were seen as a tendency for growth in the first hour and to shrink less overall, during the course of the day.
Measurement of Tissue Compressibility Using MR Tagging
Authors: O’Dell W. G. , Moore C. C. , McVeigh E. R.
Published: July 2023

Purpose The evolution of local 3D tissue compressibility in the heart wall may be a sensitive indicator of myocardial perfusion. Characterizing the compressibility of the myocardial tissue in the intact heart is also crucial for the accurate prediction of wall stresses using finite element analysis[1].
Dynamic Flexion Stiffness of Mid-Cervical Intervertebral Joint
Authors: Voo Liming , Pintar Frank A. , Yoganandan Narayan , Liu Y. King
Published: July 2023

Cervical spinal motion segments (two vertebrae and one joint) from fresh human cadavers were tested in sagittal flexion with both quasistatic and high rates of dynamic loading up to 2033 deg/s. The flexion moment was applied by an anterior compressive force through a long lever arm. Each specimen was subjected to three cycles of quasistatic loading and then a single impulsive loading to failure. The resulting moment-angulation characteristics were analyzed to examine their sensitivity to the rate of loading. The experimental dynamic flexion stiffness was found to be 67% higher than the quasistatic stiffness.