bluuebunny/crossref_metadata_2025 huggingface dataset:
Linking Molecular to Cellular Biomechanics With Nano- and Micro-Technology
Authors: LeDuc Philip
Published: May 2008

The link between mechanics and biochemistry has been implicated in a myriad of scientific and medical problem, from orthopedics and cardiovascular medicine, to cell motility and division, to signal transduction and gene expression. Most of these studies have been focused on organ-level issues, yet cellular and molecular level research has become essential over the last decade in this field thanks to the revolutionary developments in genetics, molecular biology, fabrication processes, and biotechnology. Developing the link between molecular and cellular biomechanics through subcellular studies can help uncover the complex interactions requisite for understanding higher order macroscopic behavior. Here, we will explore the link between molecular and cellular research through novel systems of nano- and micro-technology. In this, I will discuss novel technologies that we have developed and are utilizing, which include magnetic needles, three-dimension cell stretching systems, and microfluidics to examine the link between mechanics and biochemistry (including structural regulation through the cytoskeleton). By combining these novel approaches between engineering and biology, this multidisciplinary research can make a tremendous impact on the studies of human health and diseases through advances in fields such as proteomics, tissue engineering, and medical diagnostics.
Transient Thermal Management Using a Confined Jet Impingement of Liquid Ammonia
Authors: Mead Ryan M. , Rahman Muhammad M.
Published: May 2008

This paper introduces the results of transient heat transfer involving a jet of liquid ammonia perpendicularly on a solid substrate of finite thickness containing discrete electronic sources on the opposite surface. The jet was confined by using a cover plate to prevent any evaporation or loss of ammonia during the heat transfer process. The numerical simulation considered both the solid and fluid regions as a conjugate problem. The equations solved in the liquid region included the conservation of mass, conservation of energy, and conservation of momentum. For the solid region, only the heat conduction equation was solved. Computed results included the temperature distribution, local and average heat transfer coefficient, and local and average Nusselt number at the solid-fluid interface. Some of the parameters such as the jet velocity, plate thickness, and plate material were altered to examine the effect that they had on the problem. It was found that the average heat transfer coefficient and a average Nusselt number were high at the initial stages of the transient process and decreased steadily with time until it reached the steady condition. As the plate thickness decreased, and as the jet velocity increased, it was observed that the time it took to reach the steady state condition declined. The time it took to reach steady state condition did not change significantly for different plate materials. However, it did change noticeably for different plate thickness and different Reynolds number.
Transient Waterhammer Force and Pipe Response Using Fluid and Structural Coupling
Authors: Prado E. , Moody F. J.
Published: May 2008

The problem presented in this report is intended to be instructive. It is designed to be a step by step approach on how pipe response due to waterhammer can be solved using fundamental engineering principles. When fluid accelerates in a piping system, the pipe experience a reaction force that is equal and opposite to the force exerted by the fluid. The relationship between fluid and structural behaviors in this type of problem can be analyzed by the fluid-structure coupling approach. This methodology takes the decoupled fluid force, predicted for a rigid pipe, and applies it to the dry pipe with an added hydraulic mass to obtain the exact coupled pipe motion response. To demonstrate the application of the fluid-structure coupling approach, an analysis of waterhammer effects due to valve closure is performed on a horizontal pipe with elbows attached to two vertical segments at both ends; both instantaneous and ramp-in-time valve closures are modeled. The analysis starts first by determining whether the fluid response corresponds to bulk flow or propagative flow. Then from conservation of mass and momentum equations, employed with the space-time diagram, the transient forcing function on the stationary, rigid horizontal pipe is determined. By modeling the two vertical piping segments as cantilever beams, and adding the appropriate hydraulic mass to the dry pipe, the piping response can be obtained. As a result, the piping response is a function of pipe geometry, initial fluid velocity, mass of pipe and fluid, and pipe stiffness. Given this fluid-structure coupled function, one can predict the maximum deflection of the pipe and the stresses induced on the pipe restraints.
Comparison of Self-Sensing Techniques for Mercury Vapor Detection Using Piezoelectric Microcantilevers
Authors: Rogers B. , Bauer C. A. , Adams J. D.
Published: May 2008

Self-sensing piezoelectric microcantilevers do not require alignment of external optics, use very little power and are well suited to array applications. We demonstrate a commercially available, piezoelectric cantilever as a mercury vapor detector. The cantilever is an atomic force microscopy cantilever with self-sensing and self-actuating capabilities. In the first detection technique, adsorption-induced bending, caused by mercury adsorption onto gold on the cantilever, is measured by bringing the resonating cantilever into intermittent contact with a reference surface. Cantilever bending causes changes in its oscillatory amplitude, detected using the voltage output of the piezoelectric film, and a piezotube in feedback is adjusted to compensate. A 50 ppb mercury concentration in nitrogen gas was detected. The second technique capitalizes on the stiffening effect adsorbed gold has on the cantilever; natural frequency changes are detected with the piezoelectric cantilever in conjunction with a bridge circuit and amplifier. A mercury concentration of 93 ppb in nitrogen is detected. These techniques are discussed and compared. Additionally, consideration is given to the effect of the location and size of the gold-adsorption pad on sensitivity.
A Physical Model of the Vocal Folds
Authors: Thomson Scott L. , Mongeau Luc , Frankel Steven H.
Published: May 2008

Voice production is a result of the nonlinear, coupled interaction between laryngeal airflow and vocal fold tissue dynamics. Studying these fluid-structure interactions can contribute to the understanding of the mechanisms of speech production, leading to improved surgical, clinical, and pedagogical care. Aside from experiments using excised larynges (e.g., Berry et al., 2001) and a model of the superficial vocal fold layer (e.g., Chan et al., 1997), no studies appear to have been reported in which self-oscillating physical models were used that were similar to the human vocal folds in the following aspects: length scale, geometry, and dynamic and mechanical behavior. This paper describes a self-oscillating physical model designed to more closely represent the human vocal folds in terms of the above key parameters. The model was constructed using a flexible polymer casting and exhibited regular, self-sustained, large-amplitude oscillations at frequencies and operating conditions close to those found in human phonation. The model demonstrated potential for further studies involving laryngeal fluid-structure interactions.
An Improved Wall-Distance-Free Version of the Baldwin-Barth Turbulence Model
Authors: Elkhoury Michel
Published: May 2008

This paper presents a modified version of the Baldwin-Barth (BB) turbulence model. This modification accounts for the asymptotic boundary value of the pseudo eddy viscosity as the wall is approached. The BB Model tends to respond strongly to an adverse pressure gradient, in the sense that it always predicts a large decrease in skin friction relative to the measured values. Hence, in the present work, the importance of the modifications for improving the skin friction prediction of flows with adverse pressure gradient is addressed. All of the implemented modifications are free of wall functions and coordinate independent, which renders the model advantageous relative to other wall dependent models. The results are compared with both the original BB and the Spalart-Allmaras (SA) models. The accuracy of these and the present model is assessed against experimental data for transonic flows over NACA-0012 and RAE 2822 airfoils. In general, good agreement with experiments is indicated.
Economics of Wayside Inspection Systems
Authors: Zarembski Allan M. , Resor Randolph , Patel Pradeep
Published: May 2008

The use of wayside load measurement sites to monitor vertical and/or lateral wheel/rail forces has been in active use in North America for many years. Recently interest has increased in establishing a network of such sites to allow for the monitoring of railway cars that generate excessive levels of vertical and/or lateral loads. This would potentially allow for the identification of these high load level vehicles and the ability to take them out of service to investigate the cause of these high levels of loading. This paper addresses the issue of the economics of such a site or series of sites. Specifically the benefits associated with both vertical and lateral load detection wayside sites are identified to include both safety related benefits (e.g. derailment reduction) and maintenance (non-safety) related benefits. These latter benefits include reduced track maintenance, reduced equipment maintenance, reduction in fuel consumption, reduction in lading damage, and reduced inspection costs. Likewise the costs to set up and operate these sites, to include capital and operating costs, as well as costs associated with “false alarms” and associated unnecessary removal and inspection of cars are defined and quantified. The resulting overall system economics, and the associated sensitivity of these costs and benefits to key operating parameters are presented and discussed.
Simulation and Bogie Testing of a New Cable Barrier Terminal
Authors: Reid John D. , Hiser Nicholas R. , Paulsen Tony J.
Published: May 2008

Roadside barriers of various designs are extensively used for the purpose of shielding obstacles along the road from impact with errant vehicles. One commonly applied roadside barrier system is a cable system, consisting of three steel cables supported by weak steel posts. Due to an increase in the use of cable systems, a tangent to the roadway, as opposed to flared away from the roadway, crashworthy end terminal has been designed by the Midwest Roadside Safety Facility. The design goal was to effectively disengage the pre-tensioned cables at the end anchor point when impacted on the end by a vehicle, allowing the vehicle to pass through the system virtually unobstructed. It is the objective of this study to help evaluate the new design through bogie testing and nonlinear finite element analysis using LS-DYNA. Based on bogie test results and detailed analysis of the simulation results, it was concluded that the new cable end terminal was ready for full-scale crash testing.
Locomotive Crashworthiness Testing at the Transportation Technology Center
Authors: Walker Russell , Spons Gunars
Published: May 2008

Transportation Technology Center, Inc. (TTCI), a wholly owned subsidiary of the Association of American Railroads (AAR), has conducted three full-scale locomotive crashworthiness tests on behalf of the Federal Railroad Administration (FRA) at the FRA’s Transportation Technology Center (TTC), Pueblo Colorado. This paper describes the second and third Phase I tests. The previous test involved a locomotive striking a standing string of hopper cars. The second full-scale locomotive impact test was performed September 10, 2002. The test involved one SD-45 locomotive, modified to meet AAR Specification S-580, and three trailing loaded hopper cars impacting a stationary log truck at a grade crossing at 50.4 mph. A third full-scale impact test, conducted December 18, 2002, involved a locomotive impacting a highway truck loaded with two steel coils on a grade crossing at approximately 58 mph. The rearmost steel coil was aligned with the right side collision post of the locomotive. An anthropomorphic test device (ATD, or test dummy) was placed seated on the floor in the nose of the locomotive, facing rearward with its back against the interior door.
Heat Transfer Enhancement in an Electrically Heated Horizontal Pipe Due to Flow Pulsation
Authors: Hessami Mir-Akbar , Berryman Andrew , Bandopdhayay Pratish
Published: May 2008

The concept of applying a periodic pulse to a fluid flow has been widely used in industrial applications for many years. One would expect flow pulsation to have a significantly positive effect on the efficiency of heat transfer. However, several decades of research into this type of flow (mainly for a gas such as air flowing in a pipe) has brought conflicting conclusions as to the advantages or disadvantages of pulsation on heat transfer. In order to study the published evidence in a more objective manner, this research project was initiated. The approach used was experimental, involving laboratory experiments with water flowing in a heated horizontal pipe. For this purpose, a special experimental apparatus was designed and built, and a large number of experiments were performed for different values of pulsation frequency and amplitude, superimposed over a varying main flow rate through the pipe. For the range of variables considered in this study (ie, 5,000 < Re < 23,000, 0.1 Hz ≤ f ≤ 1.0 Hz and various pulsation amplitudes), it was found that (a) increasing pulsation frequency improved the heat transfer by as much as 15%, (b) increasing pulsation amplitude reduced the heat transfer by as much as 25% and (c) up to 50% heat transfer enhancement was obtained for pulsatile flows with flow reversal.
Supervised Operation Monitoring and Control System of Rotating Rolls
Authors: Salmenpera¨ Pekka , Miettinen Juha
Published: May 2008

The dynamic behavior of rotating machinery depends on the construction and foundation of the machine and in addition of the machine running parameters. By choosing appropriate parameters it is possible to influence considerably on the vibration of the machine. By driving the machine in that kind of an advantageous running window it is possible to minimize the vibration of the machine and to improve the quality of the product, but not to lose the efficiency of the productivity. Machines where the running window is important in maximizing the quality of the product are rotating cylindrical rolls in line contact for example in paper machines and grinding machines. In that kind of machines resonance situations are the most dangerous operation situations. The on-line measurement from rotating machine components requires wireless measurement data transfer applications. Sophisticated systems for that purpose need transfer capacity of several channels and two-way communications. Two-way communications allows the control of the measurement, versatile analysis of measurement signals and the control or supervised control of the running situation of the machine. If network solutions, for example via www are used, it is possible to use remote operation monitoring and control. In this paper a supervised operation monitoring and control system of a pilot roll station at Tampere University of Technology is described. The main components of the system are measurement unit on the end flange of the rotating roll, wireless local area network for measurement data transfer from the rotating roll to the control room computer and the local area network that connects the process control and signal analysis computers together. The system contains also a WWW-based remote control system for measurement signals from the rotating rolls and for the process variables. One possibility in this kind of complicated control situation is to use the fuzzy logics principle. Fuzzy logics are principally suitable for process control when knowledge-based systems fit well in diagnostics. However, fuzzy rule-based control can be defined as a knowledge-based system. For finding out the suitable running windows in the pilot roll station a fuzzy rule-based, supervised roll rotational speed control system is used. The paper describes also the fuzzy systems and comprises preliminary experimental results.
Enhancing the Acoustic Absorption Properties of Needlepunch Nonwovens
Authors: Montgomery Eliza L.
Published: May 2008

This study encompasses the initial development of new acoustic absorbing materials for use in aircraft interiors. Current needlepunch nonwoven materials used as acoustic absorbers were characterized using three methods, the measurement of acoustic absorption coefficient, poroelastic parameters, and process factors. In order to show true improvement in the sound quality of an aircraft, two factors are considered: weight loss and noise reduction. An ideal material solution would include reducing the weight while also reducing the noise level. Although the attempt is to do both, a realistic goal for a new material is to reduce weight while maintaining current acoustic absorption values. This research is the initial characterization and development work for the formation of a new acoustic sound package for use in aircraft interiors.
A Stochastic Approach on the Tear Behavior of Coated Fabrics With Interphase
Authors: Zhong Wen , Pan Ning , Lukas David
Published: May 2008

A stochastic approach, the Ising model combined with Monte Carlo simulation, is employed to study the process of a tongue tear process of coated fabrics. The complicated mechanisms involved can be realistically simulated with a relatively simple algorithm. The important factors, especially the interphase between the coating and the fabric, influencing the tear behavior, formation and failure of the del-zone can be represented by the corresponding coefficients in an energy expression of the system. The results of parametric studies are in good qualitative agreement with the behavior of real systems, indicating the usefulness of this approach in the studies of similar interfacial phenomena.
Vehicle Health Monitoring System Development and Deployment
Authors: Anderson Gerald B. , McWilliams Ryan S.
Published: May 2008

Over the last several years the North American railroad industry has seen a determined growth in the area of advanced vehicle health monitoring systems, such as wheel impact load detectors, truck performance detectors, hunting detectors; and more recently, in low hanging air hose detectors, acoustic bearing detectors, and wheel profile measurement systems. The interest in performance-based monitoring is high and growing. Latest developments by Transportation Technology Center, Inc. (TTCI), a wholly owned subsidiary of the Association of American Railroads (AAR), are in the initial stages of deployment and include acoustic roller bearing detectors and truck performance detectors. Together, these detectors and others still in development look to provide railroads and car owners with information on car component performance that can lead to preventive or predictive maintenance. This paper will describe the development and deployment of the Trackside Acoustic Detection System (TADS) and Truck Performance Detector (TPD) by TTCI in North America and internationally.
Investigation of a Centrifugal Compressor Stage With Two Volutes and the Same Impeller
Authors: Dai Yinghui , Engeda Abraham , Cave Michael , Di Liberti Jean-Luc
Published: May 2008

Volute scroll, conic diffuser and sudden expansion discharge loss account for 4–6 points of efficiency decrement in a typical centrifugal compressor stage. The flow in a volute is highly complex. It is strongly believed that understanding of the detailed flow structure in a volute will provide insights on minimizing the losses by isolating the mechanisms that contributes to entropy generation. The result will be a more efficient centrifugal compressor product for customers and users and a product at higher profitability levels for manufacturers. This paper presents the experimental and numerical investigation on the matching of two different overhung volutes to the same centrifugal compressor impeller. The experimental data were measured from flange to flange firstly, then three Kiel probes were installed on pinch position circumferentially. At the same time, a detailed numerical simulation of the performance of the two volutes has been carried out. A computational model, using the k-ε turbulence model and the wall function, has been used to predict the internal flow of the both volutes. A good agreement between experimental data and numerical simulation results is found. The overall performance of the two volutes was also discussed in detail.
Correlation for Performance Prediction of Novel Natural Convection Heat Exchanger for Cooling Power Transformers
Authors: Ele Abraham Y. , Brescacin Laurie J.
Published: May 2008

In an attempt to collect design data for a novel natural-convection heat exchanger, a test program was undertaken. The Aluminum Natural Convection Radiator (ANR) [1], consisted of tubes with external axial fins. The fins of adjacent tubes in the bundle interlock to create an air channel that runs parallel to the axis of the tubes. A test setup consisted of full scale heat exchangers of different sizes installed on an oil tank in which oil is heated using condensing steam. Hot oil entered the heat exchanger at the top and moved down the tubes as the result of buoyancy driven convection. The cooling air entered the channels, formed by the interlocking fins, at the bottom of the heat exchanger and moved counter current to the oil flow. Measurements of oil temperature, air temperature and heat dissipated by the cooler was made. The average heat flux was observed to decrease with the length of the heat exchanger. Functional relations were found between average Nusselt number, channel Rayleigh number and length-to-diameter ratio of the air channel. The non-dimensional curve shows two distinct regions which is believed to signify change in the boundary layer of the air flow.
Static and Fatigue Analysis of a Single Point Mooring Jacket
Authors: Yao Yanping
Published: May 2008

StruCAD*3D program is used to perform the static and fatigue analysis of a Single Point Mooring (SPM) jacket in the present paper. The static analysis is conducted for members and joints under operating, extreme, and ice conditions, respectively. Nominal stress for members and punching shear stress for critical joints are checked according to the allowable stress. Deterministic approach is used for the detailed fatigue analysis of this jacket, in which the direct wave loading and high frequency mooring force are linearly combined in one load case, while the low frequency mooring force is treated as separate load case. The fatigue damage is analyzed separately and added to obtain the total damage. In the damage calculation API-X’ curve and Airy wave theory is used and the fatigue life of critical tubular joints is evaluated by using appropriate safety factors. This paper can be a reference for the design and in-place safety assessment of jackets and platforms.
Parallel Iterative Finite Element Solution Methods for Three-Dimensional Acoustic Scattering
Authors: Ianculescu Cristian , Thompson Lonny L.
Published: May 2008

Efficient and scalable parallel solution methods are presented for three-dimensional acoustic scattering problems on unbounded domains. A separable boundary is applied at an arbitrary distance from the scatterer, to define a finite computational domain, and thus enable application of the Finite Element Method (FEM). A modified non-reflecting Dirichlet-to-Neumann (DtN) boundary condition is applied along the truncation boundary, in the form of local second-order differential operators, and a harmonic series. For elongated scatterers (e.g. a submarine or ship), suitable finite element formulations are derived and implemented on spheroidal coordinates, reducing the size of computational domain without affecting the accuracy of the numerical solution. The outer-product structure of the DtN boundary operator is exploited to efficiently handle non-locality in an iterative process. Computational performance of the DtN condition is analyzed and shown to be significantly more cost-effective when compared with local boundary conditions producing similar accuracy. The effective use of non-local DtN conditions in a 32-processor parallel distributed memory environment is demonstrated for a three-dimensional submarine scatterer. By exploiting the outer-product structure, it is shown that communication costs due to non-locality depend only on a small number of harmonics in the DtN operator, and thus have little impact on the scalability of the solution on multiple processors.
Thermo-Mechanical Design of a High-Temperature Silicon Carbide Micro-Channel Heat Exchanger
Authors: Wilson Merrill A. , Quist Steven M.
Published: May 2008

Efficiency and emissions of advanced gas turbine power cycles can be improved by incorporating high-temperature ceramic heat exchangers (see Figure 1). In cooperation with the DOE, preliminary development and testing of SiC based structures has been completed. This program has focused on four initial areas: thermo-mechanical degradation as a function of the chemical operating environments, design of a layered microchannel heat exchanger, thermo-mechanical testing and analysis of these structures, and fabrication development through rapid prototyping techniques.
An Energy Boundary Element Formulation for Predicting the Acoustic Field Around a Vehicle at High Frequencies Due to Airborne Noise Sources
Authors: Wang Aimin , Vlahopoulos Nickolas , Zhu Jason , Qian Mike
Published: May 2008

An Energy Boundary Element Analysis (EBEA) formulation is presented for calculating sound radiation from a source with arbitrary shape at high frequency. The basic integral equation for the EBEA is derived including a half-space boundary condition. The time and frequency averaged acoustic energy density and acoustic intensity constitutes the primary variables of the new formulation, and the corresponding Green’s functions are derived. The governing equations for the EBEA are established and the numerical formulae for the coefficients of the system matrix, the acoustic energy density, and the acoustic intensity are derived using a Gaussian quadrature. The EBEA formulation and the corresponding numerical implementation are validated by comparing EBEA results to test data for the acoustic field around a vehicle that originates from an airborne noise source. Good correlation is demonstrated between numerical predictions and test data.
Overview of Sonic Boom Noise
Authors: Sparrow Victor W.
Published: May 2008

This paper provides an overview of sonic boom noise for nonspecialists. A brief description is provided and a source/path/receiver model is emphasized. Significant research has been undertaken in the last few years to develop commercial aircraft (sources) that have sonic booms that are less loud than previous designs, opening the possibility for overland supersonic flight. This work is continuing. However, there are several challenges remaining regarding the propagation (path) of sonic boom noise through the real atmosphere and in the human perception (receiver) of minimized sonic boom waveforms.
Benefits of Rake and Skew for Turbulence Ingestion Noise
Authors: Gavin Joseph R. , Lysak Peter D. , Jonson Michael L. , Lauchle Gerald C.
Published: May 2008

Turbulent flow through a fan or pump produces a broadband spectrum of unsteady lifting forces on the blades. These forces cause undesirable blade stresses, blade vibration and sound. Jonson (1994) has shown that broadband improvements can be obtained by adding rake and skew to the stacking line of rotor blade sections. This paper adds understanding to those experimental results, and shows that benefits can be reliably predicted using analytical methods.
Stability of Hadley Circulations in a Viscoelastic Fluid With Deformable Free Surface
Authors: Kaloni P. N. , Lou J. X.
Published: May 2008

This paper deals with liner convective stability analysis of Oldroyd B fluid in a thin horizontal layer with a deformable free surface. The lower surface of the layer is in contact with an adiabatic rigid plate and the upper deformable surface is subject to a temperature dependent surface tension. The eigenvalue problem is solved by the Chebyshev Tau-QZ method and the results for various different forms of upper surfaces are presented.
Numerical Simulation of Polymer Melt Flow Control for a Multi-Cavity Mold During Injection Molding Processes
Authors: Pinarbasi Ahmet , Layser Gregory S. , Coulter John P.
Published: May 2008

Process control is an important factor for improving the performance and consistency of thermoplastic parts manufactured by injection molding processes. A critical process parameter for manufacturing of high quality plastic parts is cavity pressure. This paper presents direct numerical simulation results of a new manufacturing concept developed to improve injection molding processing for all runner types by monitoring shot to shot product quality and controlling the filling of multi-cavity molds in real time. A cold runner system supplying polymer melt to a two-cavity mold incorporating mechanical valves in the runner systems was modeled. Each valve was controlled independently to meter flow and pressure to its portion of the mold. Simulations were performed for two different materials: PPS Ryton R-4-200 and LCP Vectra E130D-2. Shear-rate dependence of viscosity of the materials is modeled through the Cross rheological equation. Flow rates and maximum shear-rates through valves were calculated and the results of the simulations were analyzed to validate the concept of individual cavity filling modification. Flow through one valve system leading to a single cavity was simulated first, followed by flow through two-valve system for filling two cavities. For one valve simulations, pressure at the inlet was specified, whereas for flow through two-valve system, volumetric flow rate at the inlet was supplied for simulations. It was concluded that the flow control concept developed was numerically validated, and it was shown that the valve system proposed here is applicable to control melt flow through cavities at industrial manufacturing facilities. The future directions for the continuing project are also discussed.
Modelling of Turbulent Transport in Laser Surface Alloying
Authors: Chakraborty Nilanjan , Chatterjee Dipankar , Chakraborty Suman
Published: May 2008

In this paper, we present a modified k-ε model capable of addressing turbulent molten metal-pool convection in the presence of a continuously evolving phase-change interface during a laser surface alloying process. The phase change aspects of the present problem are addressed using a modified enthalpy-porosity technique. The k-ε model is suitably modified to account for the morphology of the solid-liquid interface. A mathematical model is subsequently utilized to simulate a typical laser alloying process with high power, where effects of turbulent transport can actually be realized. The three-dimensional model is able to predict the species concentration distribution inside the molten pool during alloying, as well as in the entire cross section of the solidified alloy. In order to investigate these effects, the turbulent simulation results are compared with those with laminar transport for same problem parameters. Significant effects of turbulent transport on penetration and the geometrical features of the molten pool are observed which is an outcome of the thermal history of the pool. The thermal history in turn determines the microstructure of the work piece, which finally governs the mechanical properties of the work piece.
Autonomous Landing for Indoor Flying Robots Using Optic Flow
Authors: Green William E. , Oh Paul Y. , Sevcik Keith , Barrows Geoffrey
Published: May 2008

Urban environments are time consuming, labor intensive and possibly dangerous to safe guard. Accomplishing tasks like bomb detection, search-and-rescue and reconnaissance with aerial robots could save resources. This paper describes a prototype called CQAR: Closed Quarter Aerial Robot, which is capable of flying in and around buildings The prototype was analytically designed to fly safely and slowly. An optic flow microsensor for depth perception, which will allow autonomous takeoff and landing and collision avoidance, is also described.
The Effect of an Embedded Heat Pipe in a Cutting Tool on Temperature and Wear
Authors: Chiou Richard Y. , Chen Jim S. J. , Lu Lin , North Mark T.
Published: May 2008

This paper presents the fundamental understanding of the effect of an embedded heat pipe in a cutting tool on temperature and wear in machining. In particular, the technique can effectively minimize pollution and contamination of the environment caused by cutting fluids and the health problems of skin exposure and particulate inhalation in manufacturing. The temperature of a tool plays an important role in thermal distortion and the machined part’s dimensional accuracy, as well as in tool life in machining. A new embedded heat pipe technology has been developed to effectively remove the heat generated at the tool-chip interface in machining, thereby reduce tool wear and prolong tool life. Experiments were carried out to characterize the temperature distributions when performing turning experiments using a cutting tool installed with an embedded heat pipe. The ANSYS simulations show that the temperature near the cutting edge drops significantly with an embedded heat pipe during machining. Temperature measurements at several locations on the cutting tool insert agree with the simulation results both with and without the heat pipe. The effect of the heat pipe on reducing the cutting tool temperature was further supported by the observations of cutting tool material color, chip color, and chip radius of curvature.
Analysis of the Nonlinear Response of a Cantilever Beam Under Deterministic and Random Excitations
Authors: Benedettini F. , Zulli D. , Vasta M.
Published: May 2008

Dynamical systems subject to random excitations exhibit non-linear behavior for sufficiently large motion. In the case of 1 d.o.f. models, the multiple time scale method has been extensively utilized in the framework of non-linear deterministic analysis to obtain two averaged first-order differential equations describing the slow time scale modulation of amplitude and phase response. In this paper a stochastic frequency-response relationship has been derived involving the response amplitude statistics and the input power spectral density. A low-intensity noise has been assumed to separate the strong mean motion from its weak fluctuations. The moment differential equations of phase and amplitude have been derived and a linearization technique applied to evaluate the second order statistics. The theory has been validated through digital simulations on a Duffing-Rayleigh oscillator and on a cantilever beam with tip force.
Investigation of the Mass Flow Sources in a Multi-Cylinder Compressor Using Frequency Response of Pressure Pulsations in the Suction Manifold
Authors: Park Jeong-Il , Adams Douglas E. , Ichikawa Yoshinobu , Bayyouk Jacob
Published: May 2008

Linear acoustic plane wave theory and a four pole parameter formulation are used to derive and solve the governing inhomogeneous equation for the forced pressure response in the simplified manifold model. The equations for estimating gas pressure pulsations in the annular cavity connected to an anechoic inlet pipe are presented. Complicated interactions between multiple cylinder valve ports in the suction manifold produce unexpected changes in the frequency response conditions for changes in the operating speed, and hence, the flow rate characteristics through the valves. From the addition of the delayed time for opening valve in the mass flow rate profiles and the comparison of the gas pulsations from experiment with those from simulation, the maximum strokes of the piston and the delayed times for opening valve can be estimated without solving the valve dynamic and thermodynamic equations. By applying the mass flow rate sinks at each valve as identified, the correlation between analytical and experimental results is shown to be much better than if the idealized, kinematically obtained source functions are used instead.
Computations of Liquid Flow and Heat Transfer in the Hearth of a Blast Furnace
Authors: Vernengo Steven , Milanovic Rade , Zhou Chenn Q. , Chaubal Pinakin , Huang D.
Published: May 2008

A blast furnace is a key facility in iron and steel making to convert iron oxides into liquid iron. The furnace campaign life is critical to the economic vitality of an integrated steel mill. The wearing of hearth refractories is widely recognized as the main limitation for a long campaign blast furnace life. Distribution of liquid iron flow and refractory temperatures have a significant influence on hearth wear. It is identified that the use of modern advanced techniques such as Computational Fluid Dynamics (CFD) provide the most cost effective solution to gauge the condition of the hearth and understand the reason for changes. In this research, a large commercial scale blast furnace hearth has been simulated using a comprehensive CFD model based on a simplified structure of deadman. The liquid iron flow pattern, temperature distribution in the liquid and the refractories, and the wearing profile in the hearth have been analyzed. A limited parametric study has also been performed. The results are promising and will be presented in the paper.
Natural Convection From a Tube Bundle in a Thin Inclined Enclosure
Authors: Liu Wei , Davidson Jane H. , Kulacki F. A.
Published: May 2008

Natural convection heat transfer coefficients for a rectangular array of eight tubes contained in a thin enclosure of aspect ratio 9.3:1 and inclined at 30 degrees to the horizontal are measured for a range of transient operating modes typical of a load side heat exchanger in unpressurized integral collector-storage systems. Water is the working fluid, and thermal charging is accomplished via a constant heat flux on the upper boundary. All other boundaries are well insulated. Results for isothermal and stratified enclosures yield the following correlation for the overall Nusselt number: NuD=(0.728±0.002)RaD0.25,4.0×105≤RaD≤1.4×107. The flow field in the enclosure is inferred from measured temperature distributions. The temperature difference that drives natural convection is also determined. The results extend earlier work for the case of a single tube and provide limiting case heat transfer data for a tube bundle that occupies the upper portion of the collector storage system.
Optimizing Piecewise Linear Isolator for Steady State Vibration
Authors: Narimani A. , Golnaraghi M. F. , Jazar R. N.
Published: May 2008

In this work we have studied the effect of stoppers in quarter car model. While in rough roads these stoppers prevent the system from excessive displacement around the resonance frequency. Although stoppers prevent the undesired motion they increase the transmitted force that is undesirable in suspension systems. In order to optimize between the relative displacement and transmitted force an analytical model is considered. The piecewise linear system is the model of presented nonlinearity which cannot be considered small. Therefore standard perturbation methods are not able to provide an analytical solution. For this case we have adopted an averaging method which leads to frequency response of the piecewise linear system at resonance. In order to confirm the results obtained by averaging method an experimental device is fabricated and frequency response of the system is measured. The experimental frequency response is in very good agreement with analytical approach and numerical simulations. Sensitivity analysis methods are used to minimize the cost function of maximum relative displacement in frequency domain. The range of the parameters that minimizes the cost function where certain amount of clearance exists in the system are obtained.
Asymptotic Analysis of Nonlinear Stochastic Equations With Rapidly Oscillating and Decaying Components
Authors: Namachchivaya N. Sri , Van Roessel H. J.
Published: May 2008

We consider a noisy n-dimensional nonlinear dynamical system containing rapidly oscillating and decaying components. We extend the results of Papanicolaou and Kohler and Namachchivaya and Lin; these results state that as the noise becomes smaller, a lower dimensional Markov process characterizes the limiting behavior. Our approach springs from a direct consideration of the martingale problem and considers both quadratic and cubic nonlinearities.
Preliminary Crossed Hot-Wire Measurements in High Reynolds Number Turbulent Pipe Flow
Authors: Zhao Rongrong , Smits Alexander J.
Published: May 2008

Crossed hotwire measurements were performed in the Princeton Superpipe facility at Reynolds number between 56 × 103 and 5.5 × 106. Normal stresses (in both stream-wise direction and wall-normal direction), Reynolds shear and spectra are reported. Inner scaling and outer scaling are applied to the data to examine the possibility of similarity scaling.
Impacts of Atmospheric Anthropogenic Nitrogen on the Open Ocean
Authors: Duce R. A. , LaRoche J. , Altieri K. , Arrigo K. R. , Baker A. R. , Capone D. G. , Cornell S. , Dentener F. , Galloway J. , Ganeshram R. S. , Geider R. J. , Jickells T. , Kuypers M. M. , Langlois R. , Liss P. S. , Liu S. M. , Middelburg J. J. , Moore C. M. , Nickovic S. , Oschlies A. , Pedersen T. , Prospero J. , Schlitzer R. , Seitzinger S. , Sorensen L. L. , Uematsu M. , Ulloa O. , Voss M. , Ward B. , Zamora L.
Published: May 2008

Increasing quantities of atmospheric anthropogenic fixed nitrogen entering the open ocean could account for up to about a third of the ocean's external (nonrecycled) nitrogen supply and up to â¼3% of the annual new marine biological production, â¼0.3 petagram of carbon per year. This input could account for the production of up to â¼1.6 teragrams of nitrous oxide (N
2
O) per year. Although â¼10% of the ocean's drawdown of atmospheric anthropogenic carbon dioxide may result from this atmospheric nitrogen fertilization, leading to a decrease in radiative forcing, up to about two-thirds of this amount may be offset by the increase in N
2
O emissions. The effects of increasing atmospheric nitrogen deposition are expected to continue to grow in the future.
Stress and Fold Localization in Thin Elastic Membranes
Authors: Pocivavsek Luka , Dellsy Robert , Kern Andrew , Johnson Sebastián , Lin Binhua , Lee Ka Yee C. , Cerda Enrique
Published: May 2008

Thin elastic membranes supported on a much softer elastic solid or a fluid deviate from their flat geometries upon compression. We demonstrate that periodic wrinkling is only one possible solution for such strained membranes. Folds, which involve highly localized curvature, appear whenever the membrane is compressed beyond a third of its initial wrinkle wavelength. Eventually the surface transforms into a symmetry-broken state with flat regions of membrane coexisting with locally folded points, reminiscent of a crumpled, unsupported membrane. We provide general scaling laws for the wrinkled and folded states and proved the transition with numerical and experimental supported membranes. Our work provides insight into the interfacial stability of such diverse systems as biological membranes such as lung surfactant and nanoparticle thin films.
Measuring Picosecond Isomerization Kinetics via Broadband Microwave Spectroscopy
Authors: Dian Brian C. , Brown Gordon G. , Douglass Kevin O. , Pate Brooks H.
Published: May 2008

The rotational spectrum of a highly excited molecule is qualitatively different from its pure rotational spectrum and contains information about the intramolecular dynamics. We have developed a broadband Fourier transform microwave spectrometer that uses chirped-pulse excitation to measure a rotational spectrum in the 7.5- to 18.5-gigahertz range in a single shot and thereby reduces acquisition time sufficiently to couple molecular rotational spectroscopy with tunable laser excitation. After vibrationally exciting a single molecular conformation of cyclopropane carboxaldehyde above the barrier to C–C single-bond isomerization, we applied line-shape analysis of the dynamic rotational spectrum to reveal a product yield and picosecond reaction rate that were significantly different from statistical predictions. The technique should be widely applicable to dynamical studies of radical intermediates, molecular complexes, and conformationally flexible molecules with biological interest.
Hidden Neotropical Diversity: Greater Than the Sum of Its Parts
Authors: Condon Marty A. , Scheffer Sonja J. , Lewis Matthew L. , Swensen Susan M.
Published: May 2008

The diversity of tropical herbivorous insects has been explained as a direct function of plant species diversity. Testing that explanation, we reared 2857 flies from flowers and seeds of 24 species of plants from 34 neotropical sites. Samples yielded 52 morphologically similar species of flies and documented highly conserved patterns of specificity to host taxa and host parts. Widespread species of plants can support 13 species of flies. Within single populations of plants, we typically found one or more fly species specific to female flowers and multiple specialists on male flowers. We suggest that neotropical herbivorous insect diversity is not simply a function of plant taxonomic and architectural diversity, but also reflects the geographic distribution of hosts and the age and area of the neotropics.
Effect of nationwide tobacco control policies on smoking cessation in high and low educated groups in 18 European countries
Authors: Schaap M M , Kunst A E , Leinsalu M , Regidor E , Ekholm O , Dzurova D , Helmert U , Klumbiene J , Santana P , Mackenbach J P
Published: May 2008

Background:

Recently a scale was introduced to quantify the implementation of tobacco control policies at country level. Our study used this scale to examine the potential impact of these policies on quit ratios in European countries. Special attention was given to smoking cessation among lower educational groups.

Methods:

Cross-sectional data were derived from national health surveys from 18 European countries. In the analyses we distinguished between country, sex, two age groups (25–39 and 40–59 years) and educational level. Age-standardised quit ratios were calculated as total former-smokers divided by total ever-smokers. In regression analyses we explored the correlation between national quit ratios and the national score on the Tobacco Control Scale (TCS).

Results:

Quit ratios were especially high (>45%) in Sweden, England, The Netherlands, Belgium and France and relatively low (<30%) in Lithuania and Latvia. Higher educated smokers were more likely to have quit smoking than lower educated smokers in all age-sex groups in all countries. National score on the tobacco control scale was positively associated with quit ratios in all age-sex groups. The association of quit ratios with score on TCS did not show consistent differences between high and low education. Of all tobacco control policies of which the TCS is constructed, price policies showed the strongest association with quit ratios, followed by an advertising ban.

Conclusion:

Countries with more developed tobacco control policies have higher quit ratios than countries with less developed tobacco control policies. High and low educated smokers benefit about equally from the nationwide tobacco control policies.