bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards the Understanding of Blood Perfusion in Tumor Vascular Networks Using Contrast-Enhanced MRI and Invasion Percolation
Authors: Craciunescu Oana , Clegg Scott T.
Published: January 2022

Accurate knowledge of the hyperthermia induced power deposition and temperature patterns are necessary to optimize the hyperthermia dose. A critical factor influencing the hyperthermia induced temperature distribution is the tumor blood perfusion. Hence, perfusion information must be available to optimize the hyperthermia therapy dose. Previous efforts to describe the tumor blood perfusion distribution for thermal analysis have relied upon the “classical” perfusion model of a highly perfused periphery and a necrotic core. However, biological structures, i.e. tumor perfusion, often cannot be described with such a straightforward Euclidean framework. To describe the irregular and fragmented non-Euclidean patterns of the tumor blood perfusion, fractal geometry is used. In particular, it has been shown that the fractal dimension of two-dimensional vascular networks resembles that of percolation clusters. In this paper, dynamic contrast-enhanced MRI is used to obtain two- and tree-dimensional images of the perfusion distribution in six canine tumors. The wash-in component of the MRI contrast signal intensity is depicted as a percolation cluster. Fractal characteristics are determined for each two- and three-dimensional percolation cluster. It is concluded that the blood perfusion in a two-dimensional tumor vessel network has a fractal structure, regardless of the tumor type and size. A preliminary three-dimensional analysis is presented that also shows a fractal structure.
X-Ray Diffraction Studies of Laser Created Amorphous Ice
Authors: Fowler Alex J. , Toner Mehmet
Published: January 2022

This paper reports on the results of x-ray diffraction studies of laser created amorphous ice. Ice is rapidly solidified by using a laser pulse to selectively target a thin ice layer that is in contact with glass at cryogenic temperatures. The laser pulse creates a region of liquid water which is in direct contact with the cold glass surface. The water refreezes at cooling rates of up to 1 million degrees per second. In this paper the effectiveness of this technique for creating amorphous ice from dilute aqueous solutions is evaluated using x-ray diffraction. It has been shown previously that this laser based freezing technique can be modified to allow for the rapid freezing of cells and tissue, and thus the ability of this technique to create amorphous ice suggests cryopreservation without cryoprotectants may be possible.
Latent Heat Release in Solute Laden Solutions: Cryobiological Effects
Authors: Devireddy Ramachandra V. , Bischof John C.
Published: January 2022

The latent heat of fusion in solute laden aqueous solutions is an important parameter in modeling and optimizing of various low temperature applications in biomedicine as well as in the food industry. It is widely reported in literature that the amount of ‘freezable’ water (or water that changes phase during freezing) is less than the total water content, by an amount denoted as the ‘bound’ or ‘unfreezable’ water (Moran, 1926; Cooke and Kuntz, 1974). Fennema et al. (1973; pp. 63–66) state that during freezing of food substances the latent heat of fusion should be assumed as ∼80% of the expected heat release based on the total water content. Thus ∼20% of the total water content is ‘bound’ and does not freeze in various foods. Further, Cooke and Kuntz (1974) report that as much as 0.8g of water/g of dissolved solids (to as low as 0.3 g of water/g of dissolved solids) is ‘bound’ or does not freeze in various biological systems (membranes, lipids, intact ribosomes, muscle cells and polypeptides). The object of this study is to measure the latent heat of fusion during freezing of various aqueous solutions using a Differential Scanning Calorimeter (DSC-7) and to correlate this to the amount of dissolved solids or solutes in the aqueous solution.
Thermodynamic Assessment of the Components Comprising an Integrated System for Cogeneration and District Heating and Cooling
Authors: Rosen Marc A. , Le Minh N.
Published: January 2022

In recent years, there has been increased interest in integrating systems for cogeneration, otherwise known as combined heat and power (CHP), and district heating and cooling. In this paper, a thermodynamic assessment is carried out of a proposed system, for which advanced engineering designs have been developed for integrating cogeneration with district heating and cooling. The system was developed by Edmonton Power for the city of Edmonton, Alberta, Canada. Energy and exergy analyses are used to attain a more complete thermodynamic understanding. The objectives of the work reported here are to develop a better understanding of the thermodynamic efficiencies and losses associated with the Edmonton System, and to establish generalized findings that may assist in efforts to improve the design of the Edmonton system and other related systems. The results are utilized, throughout the present investigation, of previous studies by the authors on (i) establishing the relevant thermodynamic principles relating to the integration of systems for cogeneration and district cooling, and (ii) developing measures of efficiency for such integrated systems.
Effect of Cost Change of a Component on the Production Costs in Thermal Systems
Authors: Kwon Yong-Ho , Kwak Ho-Young , Oh Si-Doek
Published: January 2022

An analysis for the effect of the annualized cost of a component on the production cost in 1000-kW gas-turbine cogeneration system was studied by utilizing the generalized exergy balance and cost-balance equations developed previously. Comparison between typical exergy-costing methodologies were also made by solving a predefined cogeneration system, CGAM problem. It was successful to identity the component which affects the unit cost of system’s products decisively. It has been found that the cost of products are crucially dependent on the change in the annualized cost of the component whose primary product is the same as the system’s product. On the other hand, the change in the weighted average cost of the product is proportional to the change in the annualized cost of the total system.
Mathematical Model for Proton Exchange Membrane Fuel Cells
Authors: Gurau Vladimir , Kakaç Sadik , Liu Hongtan
Published: January 2022

A two dimensional, non-isothermal mathematical model for the entire sandwich of a proton exchange membrane (PEM) fuel cell including the gas channels is developed. To take into consideration the real concentration distributions along the interface between the gas diffuser and catalyst layer, transport equations are solved simultaneously for the domain consisting of the coupled gas channel, gas diffuser, catalyst layer and membrane. The selfconsistent schematical model for porous media is used for the equations describing transport phenomena in the membrane, catalyst layers and gas diffusers, while standard Navier-Stokes, energy transport, continuity and species concentration equations are solved in the gas channels. A special handling of the transport equations enabled us to use the same numerical method to solve them, and therefore to treat the gas channel-gas diffuser-catalyst layer domains as an entirety, avoiding arbitrary boundary conditions at their interfaces. The oxygen mole fraction distribution in the coupled cathode gas channel-gas diffuser is studied for different values of the operating current density. Influences of the inlet conditions at the gas channel entries and of the gas diffuser porosity on the cell performance are also analyzed.
Estimation of the Thermodynamic Properties of Hydrocarbons
Authors: He Hui , Metghalchi Mohamad , Keck James C.
Published: January 2022

A simple model has been developed to estimate the sensible thermodynamic properties such as Gibbs free energy, enthalpy, heat capacity, and entropy of hydrocarbons over a wide range of temperatures. The model is based on statistical thermodynamic expressions incorporating translational, rotational and vibrational motions of the atoms. A relatively small number of parameters are needed to calculate the thermodynamic properties of a wide range of molecules. The calculated results are in good agreement with the available experimental data for unbranched hydrocarbons. The model may also be used to make estimates for molecules whose properties have not been measured and is simple enough to be easily programmed as a subroutine for on-line kinetic calculations.
Experimental Investigation of Marangoni Effect in Aqueous LiBr Solution With Additives
Authors: Kang Yong Tae , Iizuka K. , Akisawa Atsushi , Kashiwagi Takao
Published: January 2022

The objective of this paper is to establish a model for inducement of Marangoni convection in aqueous LiBr solution with heat transfer additives. Basic mechanism of Marangoni convection was introduced from the viewpoints of the surface tension and the interfacial tension gradients. The Wilhelmy plate method was used to measure the surface tension and the interfacial tension of various heat transfer additives such as n-Octanol, 2-Octanol, 3-Octanol, 4-Octanol, n-Decanol, 2-Decanol, 3-Decanol and 2-ethly-1-hexanol. It was found that the salting-out model can not be a general criterion for inducement of Marangoni convection. The salting-out effect is a trigger for inducement of Marangoni convection before the additive solubility while the imbalance of the surface tension and the interfacial tension is a trigger for inducement of Marangoni convection after the solubility. The surface tension gradients by the solution temperature is not a trigger for inducement of Marangoni convection. The interfacial tension gradients by the LiBr concentration and the solution temperature can not be an initial cause for inducement of Marangoni convection. However, the magnitude of the interfacial tension plays an important role for inducement of Marangoni convection.
The Heat Pump in Sea Water Distillation
Authors: El-Sayed Yehia M.
Published: January 2022

The production of fresh water from the sea is one of the applications that can benefit from the use of the simplest form of the heat pump. The benefit is in product cost as well as in system efficiency. What is missing is an appropriately designed low pressure head large volumetric flow steam compressor.

The paper addresses the design aspects of the needed compressor. A design model of a conventional axial compressor and that of an unconventional radial inflow compressor are generated for performance/cost analysis. The models allow few alternative design features to be investigated.

The heat pump-based system and the system of the current distillation practice of cogenerating power and water are compared on a cost-efficiency plane under a common economic environment. A steam compressor rated at a cost below $3000/kW and of adiabatic efficiency higher than 85% can give the lead to the heat pump-based system.
Solution of Heat Transfer Problem by the Differential Quadrature Element Method
Authors: Chen Chang-New
Published: January 2022

The differential quadrature element method (DQEM) has been proposed. The element weighting coefficient matrices are generated by the differential quadrature (DQ) or generic differential quadrature (GDQ). By using the DQ or GDQ technique and the mapping procedure the governing differential or partial differential equations, the transition conditions of two adjacent elements and the boundary conditions can be discretized. A global algebraic equation system can be obtained by assembling all of the discretized equations. This method can convert a generic engineering or scientific problem having an arbitrary domain configuration into a computer algorithm. The DQEM steady-state heat conduction analysis model is developed.
Heat Pumps Using Organometallic Liquid Absorbents
Authors: Feldman K. Thomas , Jensen Craig M. , Kim Kwang J. , Razani Arsalan
Published: January 2022

A family of new organometallic liquid absorbents have been invented and are being developed for heat pump and cryocooler applications. Both hydrogen absorbing “HySorb liquids” and nitrogen absorbing “NiSorb liquids” have been synthesized in the laboratory and their properties are being measured. Previous research has shown that some organometallic substances can absorb large amounts of hydrogen — up to several weight percent, but all of the previously reported materials are solids. The only reversible hydrogen or nitrogen absorbing organometallic materials known that are liquids are the HySorb and NiSorb liquids. These liquid absorbents are environmentally clean, have 1–13 wt.% gas uptake capacity and have ΔH/cp up to 15 times higher than that of ammonia/water or lithium bromide/water, so more compact, higher power density heat pumps are possible. These liquids are also non-corrosive, compatible with oils and may be readily pumped through conventional heat exchangers, absorbers and desorbers. Compressor driven and heat driven heat pumps and cryocoolers are described. Analysis of the NiSorb heat pump indicates that high efficiencies are possible.
High-Performance Logistics-Fueled AMTEC Portable Power System
Authors: Loftus Peter J. , Pellizzari Roberto O. , Gauba Gautam , Mital Rahul , Sievers Robert K.
Published: January 2022

When integrated into an efficient logistics-fueled thermal source, Alkali Metal Thermal to Electric Conversion (AMTEC) technology has a number of advantages for portable power generation applications. The AMTEC converters have no moving parts and have the potential to provide efficient, quiet, reliable and low-maintenance electric power. Thermal integration with a liquid-fueled combustion system provides fuel flexibility, low thermal signature, and ability to operate over a wide range of ambient conditions.

Arthur D. Little, Inc. (ADL) and Advanced Modular Power Systems, Inc. (AMPS) are developing a compact prototype, logistics-fueled, 500 W power system which integrates AMTEC technology with an efficient multi-fuel thermal energy source. This work is being supported by DARPA and the Army Research Office. AMTEC technology has demonstrated thermal to electric conversion efficiencies and power densities which make it an attractive option for meso-scale power generation. We are currently targeting 20% AMTEC thermal efficiency and 16% system efficiency (fuel to net power) in a system that weighs 9 kg. The heat source under development is a compact, recuperated combustion system capable of operating with most common liquid or gaseous fuels. The careful integration of the two systems with compact and efficient heat exchanging devices can lead to power systems that meet DARPA’s challenging power and weight goals.

The overall system design and the system tradeoff analyses are described together with a summary of the results of ongoing experimental work relating to: (1) critical enhancements to the AMTEC cell technology and testing of the annular cell configuration; and (2) performance of the multi-fuel micro-combustor and recuperator.
Discrete Wavelet Analysis of Acoustic Emissions During Fatigue Loading of Carbon Fiber Reinforced Composites
Authors: Kamala Girish P. , Hashemi Javad , Barhorst Alan A.
Published: January 2022

Acoustic Emissions (AE) are generated during operational loading of Fiber Reinforced Composite (FRC) materials due to various sources of fracture. These sources which include matrix fracture, fiber fracture, splitting and delamination could be generated individually or simultaneously. The multiplicity of defects and failure modes creates problems in identifying and distinguishing various sources of emissions. This analysis is further complicated due to the friction related emissions (generated during grating of newly generated damage surfaces and fretting of broken fibers with matrix) that mask the actual signal and in most cases, exceeds the emissions from actual damage. The objectives of this research was to decompose the AE signals into different levels based on frequency, identify frequency of friction based emissions and to associate various failure modes with specific frequencies.

Through utilization of Wavelet transforms, it became possible to present the spectral composition of a transient signal (AE signal) in a time-frequency map. The results indicate that Wavelet analysis would be an effective tool in the analysis of AE by providing information relative to the frequency of the emissions and assist researchers in determining the extent and type of damage during online inspection of component.
Effects of Bolt Threads on the Stiffness of Bolted Joints
Authors: Lehnhoff Terry F. , Bunyard Bradley A.
Published: January 2022

Axisymmetric finite element analysis (fea) was performed on bolted joints to determine the effects of the threads on the bolt and member stiffnesses. For steel members, the member stiffness decreased 37.1, 37.7, 38.2, 41.0, and 49.4 percent for the 24, 20, 16, 12, and 8 mm diameter bolts, as the magnitude of the external load was increased. The external load was increased from zero to the value that caused the bolt force to equal its proof strength. The member stiffness for aluminum members decreased by 22.7 and 29.9 percent for the 24 and 20 mm bolts. The cast iron members had decreases of 26.9 and 32.3 for the 24 and 20 mm bolts. Likewise, the aluminum/cast iron members decreased in stiffness by 25.5 and 30.0 percent for the 24 and 20 mm bolts. The member stiffness with no external load applied decreased by approximately 65 percent when changing from steel to aluminum members, 53 percent from steel to cast iron and 60 percent from steel to aluminum/cast iron. Bolt stiffness varied less than 1.4 percent over the total range of the externally applied load for each of the bolted joint models. The decrease in bolt stiffness for the 24 and 20 mm diameter bolts was approximately 4 percent when changing from steel to aluminum members, 7 percent when changing from steel to cast iron members, and 8 percent when changing from steel to aluminum/cast iron members. Comparison is made to research results which did not include the influence of the threads.
The Effect of Stiffening on the Stress Concentration in a Flat Plate With a Hole
Authors: Duchek Michael G. , Lehnhoff Terry F.
Published: January 2022

This research was on the effectiveness of stiffeners fastened on either side of a hole or cutout in a flat plate loaded in tension for reducing stress concentrations at the edge of the cutout. Stress data has been compiled from sixteen flat plate geometries having various hole diameter-to-plate width ratios. Each plate was modeled using an analysis software package and solved without stiffening, and then with stiffeners located at various distances from the hole.

The reduction in the maximum stress in each plate geometry for stiffening at various distances from the hole was consistent. The stiffener positions closest to the hole always provided the greatest stiffening. The stress concentration in the plates was reduced 24%–41%. The largest reduction occurred in the plate with the largest hole diameter-to-plate width ratio. As the stiffeners moved farther from the hole, these reductions in the plate maximum stress dropped to as little as 11%. The number and location of the fasteners made a difference in the effectiveness of the stiffeners. Fasteners closest to the cutout were most instrumental in reducing the stress when the stiffeners were close to the hole.
Thermal Shape Vectors in Finite Element Shape Optimization of a Steering Knuckle
Authors: Krishna Murali M. R. , Fetcho Michael R.
Published: January 2022

The application of shape optimization using shape vectors, generated by thermal loading, has been presented. A steering knuckle is to be redesigned for weight reduction. Since it is not uniform in shape, it is very cumbersome to use traditional loads and/or displacement methods to generate shape vectors. So different regions of the steering knuckle are subjected to thermal loads independently, and the resulting displacements are used as shape vectors. Shape optimization is performed in MSC/NASTRAN using ‘Direct Linearization’ method. Design directions have been obtained to reduce its weight by 7.6%. In conclusion, thermal displacements can be used in shape optimization of a steering knuckle.
The Effects of Critical Stitching Parameters on a Stitched Composite Laminate
Authors: Pan Tien S. , Herrington Paul D.
Published: January 2022

The objective of this paper is to determine the effect of several critical stitching parameters on the structural performance of a composite laminate. The stitching parameters investigated include stitch diameter, material, and density. To investigate the effect of these parameters, a composite plate was modeled as an orthotropic laminate supported at discrete locations by an elastic foundation. The locations of support are those strands of fiber that traverse through the thickness of the laminate, with the stiffness of the foundation proportional to the stiffness of the fiber threads. Solutions are obtained by using the equilibrium method for finding critical buckling loads. Results are given for a variety of stitching thread diameter, material, and density.
An Attachment Level Design Process for Snap-Fit Applications
Authors: Bonenberger Paul R.
Published: January 2022

The Attachment Level Methodology (ALM) defines a snap-fit as a system of interacting features. This leads to a fundamental paradigm for understanding and developing snap-fit attachments. Thus, the ALM is a design for assembly (DFA) enabler.

The methodology was created to improve snap-fit development from concept through detailed design. The ALM supports profound understanding of snap-fits through its content and organization. It also supports a rational yet creative development process for snap-fit applications.

Previous papers have described specific aspects of the ALM: (key requirements, elements and enhancements). This paper describes how they are used in a step-by-step snap-fit development process. In addition to ensuring that important interface criteria are considered in a logical manner, this process encourages creativity and improved spatial reasoning during snap-fit development.

A review of attachment level terminology is provided. The snap-fit development process is then described. Feasibility of extending the process to other attachment methods is also noted.
Process Improvement Using Assembly Analysis Method
Authors: Shetty Devdas , Campana Claudio , Kondo Jun
Published: January 2022

This paper examines an approach to evaluate the installation of a product, by highlighting the strengths and weaknesses of the assembly process. It also discusses the Assembly Analysis Technique as a tool for Design for Installation and discusses the merits with the help of industrial case studies. One example considered is on the subject of field-installation of a product and the second example is on the packaging and handling process. The case study shows the suitability of the Assembly Analysis Technique for installation and packaging of a new product.
New Pathways to Microcellular and Ultramicrocellular Polymeric Foams
Authors: Handa Y. Paul , Zhang Zhiyi
Published: January 2022

Cellular polymers with closed cells about 10 μm in size and a cell density of 108 cells/cm3 and higher are called microcellular foams (Martini-Vvedensky, 1984) and those with cells less than 1 μm in size and cell density greater than 1012 cells/cm3 are called ultramicrocellular foams. The latter have also been termed supermicrocellular foams (Baldwin et al., 1994). Microcellular foams have been made by saturating the glassy polymer with a blowing agent, usually CO2, and then inducing cell nucleation by a rapid temperature soak (Kumar, 1993) or a pressure quench (Goel and Beckman, 1994). The cells are allowed to grow for a short duration before the cellular morphology is locked-in by rapidly cooling the system. Ultramicrocellular foams have been made the same way except that saturation with the blowing agent is done at a much higher pressure (Baldwin et al., 1994; Goel and Beckman, 1994).
Fibroin and Polymer-Based Fibroporous Biomaterials: Candidate Materials for Biomechanical Implants?
Authors: Sanders Joan E. , Bishop Sam T. , Stiles Charlotte E. , Schuessler Philipp K.
Published: January 2022

A technique from the paper manufacturing industry was used to manufacture fibroporous meshes for potential biomaterial implant applications. Meshes were made from small diameter (10 μm) bombyx mori cocoon silk (fibroin). Meshes with a range of fiber lengths were created, though at long fiber lengths flocculation (clumping of fibers) tended to occur. Load-deformation curves were nonlinear with lower slopes at high loads than at low loads, contrary to natural soft-tissue biomaterials. Single fiber in vivo studies to evaluate tissue response sensitivity to biomaterial architectural features demonstrated reduced fibrous encapsulation for smaller diameter fibers (2.6 μm) than larger ones (10 μm). Thus the use of small diameter fibers in biomaterial fibrous implants is a viable concept, and it should be pursued. However, alternative methods to the paper manufacturing process will need to be used for mesh fabrication.
Experiments on the Impact Strength of Microcellular Polycarbonate
Authors: Barlow Chris C. , Kumar Vipin , Weller John E. , Bordia Rajendra K. , Flinn Brian
Published: January 2022

The effects of density and cell size on the impact behavior of microcellular polycarbonate (PC) were investigated. A flexed-beam Izod impact test was conducted and the impact strength was observed to improve over the virgin polycarbonate’s impact strength for foam relative densities of 60% and above. In terms of cell size, the impact strength increased with increasing cell size. The impact strength of these foams appears to be a strong function of both density and cell size.
On the Fluid Dynamics of Adaptive Airfoils
Authors: Jacob J. D.
Published: January 2022

This paper discusses issues and practical requirements for an adaptive wing in relation to currently available technology. Adaptive wings offer many benefits, but a viable wing will require research into several areas, including selection of initial and perturbed airfoil shapes, steady and unsteady aerodynamic analysis of adaptive airfoils, and methods for real-time shape control of an adaptive wing system. An overview of adaptive wing history is briefly covered, including some recent developments. Development considerations for an adaptive wing system are then discussed. Aerodynamic performance and stability should be considered in the context of the wing’s structural integrity and aeroelasticity. Particular attention should be paid to the unsteady nature of the flow, as standard quasi-steady flow analysis techniques should be abandoned due to the rapid changes in wing shape and motion. Due to the large number of variable and measured parameters, an advanced control system is required to relate the flight conditions with changes in geometry. Issues related to adapting wings to various aircraft scales will be discussed, specifically micro aerial vehicles (μAVs). unmanned aerial vehicles (UAVs or RPVs), full-scale aircraft, and ornithopters.
Gun Muzzle Control System Using Barrel Mounted Actuator
Authors: LaVigna Chris , Kwatny Harry , Blankenship Gilmer , Teolis Carole , Mattice Mike , Li Yaowen , Sirkis James
Published: January 2022

The development of an innovative gun pointing control system consisting of a gun barrel mounted high force actuation system, a modal filter sensor system, and a control system for the 30-mm Apache chain gun is described. The actuation system utilizes piezoelectric stack elements arrayed around the barrel to apply large torques directly to the gun barrel for improved control of the gun line of sight (LOS). By exploiting the spatial integrating nature and the coupling of strain to optical propagation in a surface mounted fiber, a barrel mounted optical fiber sensor system is designed which acts as a modal filter. The design, implementation, and testing of a control system for the 30-mm Apache chain gun test bed and the gun barrel mounted actuation system are described. The results of the system testing using gun recoil disturbance simulation and turret slewing inputs show that a significant improvement in gun system LOS error can be achieved.
Shape Control of Deployable Membrane Mirrors
Authors: Martin Jeffrey W. , Main John A. , Nelson George C.
Published: January 2022

Currently the Hubble Space Telescope is able to look further into the universe than was previously possible with conventional earth-based telescopes. Since launching of large telescopes is limited by the weight and size constraints of the shuttle cargo bay, alternate telescope designs must be developed to surpass current capabilities. One possible approach is to form large telescope primary mirrors from membrane materials and provide active control to maintain the proper shape. This paper discusses results from recent research into electron gun shape control of a piezoelectric film bimorph mirror. Observations on the electron energy level/voltage control responses and the glue layer interactions are discussed.
Vulnerability of Embedded Bragg-Grating Sensors to Impact
Authors: Jarlås Rolf , Levin Klas
Published: January 2022

Vulnerability of embedded Bragg grating sensors to impact has been studied in composite laminated plates. The effects of the distance from the supporting boundary and the sensor thickness position were determined. The main objective was to develop an accurate numerical procedure to calculate the local stresses at the sensor from impact in order to determine the criticality with respect to damage initiation. A semi-analytical and a finite element based method were used to consider the contact at impact. From the analysis, it was found that a lower impact energy was required to cause damage in the sensor region when the sensor was embedded close to the boundary. At locations far from boundaries, sensors should not be embedded close to the plate surfaces. For sensors embedded close to a boundary, a thickness position close to the upper surface was found to be less suitable than other positions.
Structural Health Monitoring Using Fiber Optic Sensing
Authors: Ross Paul , Chen Peter , Wagreich Richard , Chen Steve , Sirkis Jim
Published: January 2022

A prototype structural health monitoring system for naval ships based on fiber optic Bragg grating and digital communications has been developed. This is a dual purpose system. Firstly, it is a fiber Bragg grating based multi-position strain sensing network. In addition, its open architecture is designed to allow the same fiber network to be used as an optical data bus to carry digitized signals from an array of existing devices on naval platforms (e.g. communications, fire control, surveillance, resistance strain data, etc.). The open architecture system was demonstrated by measuring the structural response of 6 foot steel beam instrumented with temperature compensated fiber Bragg grating strain sensors at 2 Hz excitation frequency to simulate primary hull bending modes. Using a hybrid wavelength and spatial division multiplexing technique, the fiber Bragg grating sensor signals were multiplexed with analog signals from resistance foil strain gages also located on the beam, and transmitted via a fiber optic data bus to a remote receiver and control computer for real time data logging and analysis. Environmental static loading tests show that fiber optic technology can provide significant improvements in accuracy, repeatability, and reliability over existing resistance foil strain gage technology under extreme humidity and temperature, characteristic of marine environments.
Design of Extruded Aluminum Space Frame Front End Structures for Crash Energy Management: Part II
Authors: Baccouche Mohamed Ridha , Mahmood Hikmat F.
Published: January 2022

This paper presents the second part of a two-part design and analysis work for crash energy management that was conducted two years ago. Part I has been presented at the 1997 ASME crashworthiness conference held in Dallas, Texas and published in the ASME proceedings AMD-Vol.225 (BED-Vol.38).

The present paper briefly reviews the components testing results and presents a detailed discussion of the CAE modeling and models results for the full front end structure of an extruded aluminum space frame. The front end structure consists mainly of a bumper, cross member, radiator support, front and backup lower rails, upper rails, shock tower support, subframe and attachments. The materials used are aluminum alloys series 5xxx and 6xxx. The 5xxx series aluminum was used only as reinforcement. The 6xxx aluminum was used as primary material for the various components as well as for reinforcing the backup lower rails.

Force-deformation response, energy absorbed during the crash event, stress distribution and failure sequences for the front end structure have been generated and plotted. A detailed discussion of the peak and mean crush load from the force-deformation response, the energy absorbing capability of the structure from the energy-deformation curve, the axial and bending stress distribution, and the order of sequence of collapse is presented in this paper. A summary list of recommendations and critical design issues is also given at the end of this paper.
Design Depowered Airbag Mass Flow Rate by Using Occupant Simulation Models and Neural Network
Authors: Liu D. S. , Chang S. Y.
Published: January 2022

This study presents to use occupant sled test simulation model in conjunction with neural network to identify proper mass flow rate for De-power airbag. Finite element models included Hybrid III crash dummy, airbag and sled buck are employed to simulate sled test. The crash pulse and the HIC number and its duration times output from full car crash test is used to calibrate this base line numerical model. Neural network model with backpropagation learning algorithm is then built. A set of candidate mass flow rate and associated dummy HIC values, chest G value output from simulation model are designated as the training pairs to adjust the weights of the neural network. Once the training complete, the target dummy HIC values, one for 50 % tile normal position, the other for 5% tile out of position, are given and input into the neural network to predict the approximated mass flow rate. Numerical examples were studied to demonstrate the feasibility of the proposed method.
ISP: An Airbag Inflator Simulation Program
Authors: Kang Jian , Wang J. T.
Published: January 2022

An inflator simulation computer program, ISP, has been developed to facilitate the assessment of transient heat transfer models. In addition to providing for incorporation of new transient heat transfer models, this program has several other useful and unique features: 1) it allows gas to have multiple chemical components, 2) it allows gas to use temperature-dependent thermodynamic properties, 3) it can self-generate gas thermodynamic properties through linkage to a chemical kinetic package CHEMKIN, and 4) it allows the users to use either cubic spline or polynomial curve fitting to smooth the noise tank test data. This program can simulate three basic tasks: inflator tank test analysis using either the average temperature method or the dual pressure method, tank test simulation, and bag deployment analysis.
A Review of Mathematical Models for Rollover Simulations
Authors: Chou C. C. , Wu F. , Gu L. , Wu S. R.
Published: January 2022

A review of mathematical models simulating rollover events under various test conditions is presented. The types of models reviewed include rigid-body-based and finite-element-based models. Simulations of FMVSS 208 rollover test procedure using a rigid-body-based model is demonstrated. Model limitations and issues are addressed to potential users/modelers regarding their applicability. Areas of further improvements over these models are also presented.
Time-of-Flight vs. Phase Contrast Techniques for MRI Velocimetry
Authors: Kutter Ella C. , Moser Kevin W. , Georgiadis John G. , Morris H. Douglas , Buckius Richard O.
Published: January 2022

Magnetic Resonance Imaging (MRI) is a non-invasive versatile tool for achieving full-field quantitative visualization. The MRI signal is a result of the interaction between radiofrequency (RF) pulses with nuclear spins exposed to a strong static magnetic field. The two main classes of techniques for MRI velocimetry are: spin-tagging techniques and phase contrast techniques. Spin-tagging techniques involve tagging and tracking a material volume of fluid. This allows a time-of-flight approach to the estimation of local velocity. Phase contrast is based on the difference in accumulated phase (time integral of angular frequency) in the signal arriving in the detector from moving and stationary spins exposed to magnetic field gradients. We compared velocity measurements with spin-tagging and phase contrast by probing the pressure-driven flow of water in a straight tube (Poiseuille flow). Profiles of the axial velocity along various cross sections were acquired for steady laminar flow with Reynolds numbers 170, 670, and 1000. Depending on the imaging sequence and Reynolds number, the velocity errors fell in the 0.5%–3.2 % range.
A Domain Decomposition Algorithm for Thermal Analysis in X-Ray Lithography With Cylindrical Geometry
Authors: Dai Weizhong , Nassar Raja
Published: January 2022

X-ray lithography is an important technique in micro fabrication used to obtain structures and devices with a high aspect ratio. The process is composed of a mask and a photoresist deposited on a substrate (with a gap between mask and resist). Predictions of the temperature distribution in the different layers (mask, gap, photoresist and substrate) and of the potential temperature rise are essential for determining the effect of high flux x-ray exposure on distortions in the photoresist due to thermal expansion. In this study, we develop a three-dimensional numerical method for obtaining the temperature profile in an x-ray irradiation process by using a hybrid finite element-finite difference scheme for solving three-dimensional parabolic equations on thin layers with a cylindrical geometry. A domain decomposition algorithm is then obtained based on a parallel Gaussian elimination for solving block tridiagonal linear systems. Numerical results show the method to be efficient.
Particulate Behavior in Micromanifolds
Authors: Valentin Gregory E.
Published: January 2022

The primary objective of this project was to design and test a manifold that would allow Beckman to measure the fluorescence of micron-size spheres. Specifically, Beckman should be able to measure the intensity and frequency of the spectra for each sphere without interference from the another sphere. The design must also allow Beckman to measure a representative sample of the beads, over 75% of those originally introduced. Second, the optical measurements should yield a high signal to background ratio, near 100:1.

Six potential designs were modeled using ADINA-F, a computational fluid dynamics (CFD) software package. The computer simulations of these six systems produced favorable results and six micromanifolds were manufactured and tested. Micromanifold experiment results have been analyzed to determine their effectiveness of meeting Beckman’s objectives and compared with CFD analysis to evaluate computer model results.
The Development of Reconfigurable Cellular Machines
Authors: Umeda Yasushi , Kondoh Shinsuke , Sato Roberto Kiyoshi , Sakao Tomohiko , Tomiyama Tetsuo
Published: January 2022

While present highly-developed mechatronics machines have many advantages, they also have problems, such as, fragility to minor faults and inflexibility to changes of the environment and user needs. In order to solve these problems, it is the key to make a product reconfigurable. Here, reconfigurability of a machine is the ability to change its functions, behaviors, and/or structure flexibly according to external and internal changes. This paper clarifies indispensable features of reconfigurable machines and proposes cellular machines as one of the most appropriate machine architecture for the reconfigurable machines. A cellular machine consists of distributed autonomous intelligent units (called “cells”). This paper also demonstrates that the cellular machines have structural reconfigurability, fault-tolerance, and functional reconfigurability which are indispensable features of reconfigurable machines.
Monitoring of Localized Gear Faults by Linear Dynamic Modeling
Authors: Li C. James , Limmer J. D.
Published: January 2022

This paper describes a method that utilizes linear dynamic modeling to track the development of localized gear faults such as fatigue cracks. A model is created from the gear meshing vibration signal when the gear is new and then the model is applied to vibration data taken over the gear’s lifetime to calculate the prediction error. This error is expected to increase over the gear’s lifetime as the “evolution” of the faults alters meshing stiffness. The method is evaluated by experimental data collected in a test where gear tooth fatigue cracks grew over time. It was found that the method gave more consistent trend when compared with state-of-the-art techniques.
Analytical Stability Prediction and Design of Variable Pitch Cutters
Authors: Altintas Yusuf , Engin Serafettin , Budak Erhan
Published: January 2022

An analytical prediction of stability lobes for milling cutters with variable pitch angles is presented. The method requires cutting constants, number of teeth, and transfer function of cutter mounted on the machine tool as inputs to a chatter stability expression. The stability is formulated by transforming time varying directional cutting constants into time invariant constants. Constant regenerative time delay in uniform cutters is transformed into non-uniform multiple regenerative time delay for variable pitch cutters. The chatter free axial depth of cut is solved from the eigenvalues of stability expression, whereas the spindle speed is identified from regenerative phase delays. The proposed technique has been verified with extensive cutting tests and time domain simulations. The practical use of the analytical solution is demonstrated by an optimal tooth spacing design application which increases the chatter free depth of cuts significantly.
Contact Mechanics of Superfinishing
Authors: Chang Shih-Hsiang , Farris Thomas N. , Chandrasekar Srinivasan
Published: January 2022

Superfinishing is an abrasive finishing process in which a smooth work surface is produced by simultaneously loading a bonded abrasive stone against a rotating workpiece surface and oscillating (reciprocating) the stone at high frequencies. The surface topography of a 600 grit aluminum oxide stone used for superfinishing is quantitatively described using scanning phase-shift interferometry. A bounded three-parameter lognormal distribution is found to provide a more accurate representation of cutting edge height distribution than a bounded normal distribution, especially in fitting the upper tail end of data. Moreover, the stone surface characteristics are nearly constant throughout stone life suggesting that superfinishing is a self-dressing process. This stone surface geometry is used to develop a contact mechanics model of the superfinishing process. The model estimates the number of cutting edges involved in material removal, the load distribution on these edges, and the resulting surface roughness of the super-finished surface. The effect of contact pressure on these estimated values has been studied. Only a very small percentage (less than 0.16%) of the cutting edges, which are comprised of the large cutting edges occurring in the tail end of distribution, are actively engaged in material removal. Further, the arithmetic average surface roughness, Ra, is found to be related to the average depth of penetration while the peak-to-valley surface roughness, Rt or Rtm, is related to the maximum depth of penetration. The prediction of surface roughness of this model is found to agree very well with experimental results for superfinishing of hardened steel surfaces.
Resistance Spot Welding: A Neural Network Approach to Modeling
Authors: Shriver Justin , Hu S. Jack , Peng Huei
Published: January 2022

This paper discusses recent progress in the development of a feedback controller for the resistance spot welding (RSW) process. Two key elements of our control architecture will be operating condition detection and nugget growth estimation. In this paper the operating condition problem is addressed with respect to five well-defined faults. We employ a novel neural network approach in the design of the operating condition detector. The nugget growth estimation problem is addressed by employing a recurrent neural network model of the process, for which preliminary results are shown.
Experimental Evaluation of the Laser Assisted Machining of Silicon Nitride Ceramics
Authors: Rozzi Jay C. , Pfefferkorn Frank E. , Incropera Frank P. , Shin Yung C.
Published: January 2022

Laser assisted machining (LAM), in which a workpiece is locally heated by an intense laser source prior to material removal, provides an alternative machining process with the potential to yield higher material removal rates and lower manufacturing costs for difficult-to-machine materials such as structural ceramics. To assess the feasibility of the LAM process, experiments were performed on silicon nitride workpieces for a wide range of operating conditions. Data for cutting forces and surface temperatures indicate that the lower bound of the material removal temperature for avoidance of cutting tool and/or workpiece fracture corresponds to the YSiAlON glass transition temperature (920–970°C). As temperatures near the cutting tool increase to values above the glass transition temperature, the glassy phase softens, facilitating plastic deformation and, correspondingly, the production of semi-continuous or continuous chips. The silicon nitride machined workpiece surface roughness (Ra = 0.39 μm) for LAM at the nominal operating condition was nearly equivalent to a value associated with the grinding of silicon nitride using a diamond wheel (Ra = 0.2 μm). Examination of the machined surfaces and chips reveals no detectable sub-surface cracking or significant changes in microstructure, respectively. Relative to grinding, the most significant advantage of LAM is its ability to achieve much larger material removal rates with high workpiece surface quality and reasonable levels of tool wear.
A New Model and Analysis of Orthogonal Machining With an Edge Radiused Tool
Authors: Manjunathaiah Jairam , Endres William J.
Published: January 2022

A new machining process model that explicitly includes the effects of the edge hone is presented. A force balance is conducted on the lower boundary of the deformation zone leading to a machining force model. The machining force components are an explicit function of the edge radius and shear angle. An increase in edge radius leads to not only increased ploughing forces but also an increase in the chip formation forces due to an average rake angle effect. Previous attempts at assessing the ploughing components as the force intercept at zero uncut chip thickness, which attribute to the ploughing mechanism all the changes in forces that occur with changes in edge radius, are seen to be erroneous in view of this model. Calculation of shear stress on the lower boundary of the deformation zone using the new machining force model indicates that the apparent size effect is mainly due to deformation below the tool (ploughing) and a larger chip formation component due to a lower shear angle. The shear strain rate is substantially higher at smaller uncut chip thickness resulting in a mild effect of strain-rate hardening. Frictional conditions do not exhibit change with uncut chip thickness if an average rake formulation is used.