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Full-Text Articles in Engineering

The Effect Of Intellidrive On The Efficiency Of Highway Transportation Systems, Mohammad Nekoui, Hossein Pishro-Nik, Daiheng Ni Dec 2010

The Effect Of Intellidrive On The Efficiency Of Highway Transportation Systems, Mohammad Nekoui, Hossein Pishro-Nik, Daiheng Ni

Daiheng Ni

Recently, the IntelliDrive initiative has been proposed by the US Department of Transportation (USDOT) to enhance on-road safety and efficiency. In this study, we provide a mathematical framework which predicts the effect of such technologies on the efficiency of multilane highway systems prior to their real-life deployment. Our study shall encompass mixed traffic conditions in which a variety of assisted, automated and unequipped vehicles coexist. We show that intervehicular communications improves the flow of vehicles by reducing the perception-reaction (P-R) times of drivers and, in some cases, allowing for more efficient lane-changing operations. As we shall see, unlike the latter, …


The Effect Of Intellidrive On The Efficiency Of Highway Transportation Systems, Mohammad Nekoui, Hossein Pishro-Nik, Daiheng Ni Dec 2010

The Effect Of Intellidrive On The Efficiency Of Highway Transportation Systems, Mohammad Nekoui, Hossein Pishro-Nik, Daiheng Ni

Hossein Pishro-Nik

Recently, the IntelliDrive initiative has been proposed by the US Department of Transportation (USDOT) to enhance on-road safety and efficiency. In this study, we provide a mathematical framework which predicts the effect of such technologies on the efficiency of multilane highway systems prior to their real-life deployment. Our study shall encompass mixed traffic conditions in which a variety of assisted, automated and unequipped vehicles coexist. We show that intervehicular communications improves the flow of vehicles by reducing the perception-reaction (P-R) times of drivers and, in some cases, allowing for more efficient lane-changing operations. As we shall see, unlike the latter, …


A Spectrum Of Traffic Flow Modeling At Multiple Scales, Daiheng Ni Dec 2010

A Spectrum Of Traffic Flow Modeling At Multiple Scales, Daiheng Ni

Daiheng Ni

his paper presents a broad perspective on traffic flow modeling at a spectrum of four scales. Modeling objectives and model properties at each scale are discussed and existing efforts are reviewed. In order to ensure modeling consistency and provide a microscopic basis for macroscopic models, it is critical to address the coupling among models at different scales, i.e. how less detailed models are derived from more detailed models and, conversely, how more detailed models are aggregated to less detailed models. With this understanding, a consistent modeling approach is proposed based on field theory and modeling strategies at each of the …


Why Should We Care About Buckling?, Alfred Crosby Oct 2010

Why Should We Care About Buckling?, Alfred Crosby

Alfred Crosby

No abstract provided.


Operating Parameters And Selectivity In Batch Reactive Distillation, W. Qi, M. F. Malone Oct 2010

Operating Parameters And Selectivity In Batch Reactive Distillation, W. Qi, M. F. Malone

Michael F. Malone

This Article provides new predictions for selectivity in batch reactive distillation, identifying the reflux or reboil ratio and a Damkhler number (Da) as the key operating parameters. The dimensionless Da incorporates the influence of liquid holdup, vapor rate, and rate of reaction. Example results for a system of serial isomerization reactions and for the synthesis of ethylene glycol are provided. The results show that selectivity improvements in BRD are limited for high values of Da or for high values of the reflux or reboil ratio and that selectivity is enhanced as Da or reflux or reboil ratio is decreased. However, …


Dynamic Flux Balance Modeling Of Microbial Co-Cultures For Efficient Batch Fermentation Of Glucose And Xylose Mixtures, Timothy J. Hanly, Michael A. Henson Sep 2010

Dynamic Flux Balance Modeling Of Microbial Co-Cultures For Efficient Batch Fermentation Of Glucose And Xylose Mixtures, Timothy J. Hanly, Michael A. Henson

Michael A Henson

Sequential uptake of pentose and hexose sugars that compose lignocellulosic biomass limits the ability of pure microbial cultures to efficiently produce value-added bioproducts. In this work, we used dynamic flux balance modeling to examine the capability of mixed cultures of substrate-selective microbes to improve the utilization of glucose/xylose mixtures and to convert these mixed substrates into products. Co-culture simulations of Escherichia coli strains ALS1008 and ZSC113, engineered for glucose and xylose only uptake respectively, indicated that improvements in batch substrate consumption observed in previous experimental studies resulted primarily from an increase in ZSC113 xylose uptake relative to wild-type E. coli. …


Preliminary Estimate Of Highway Capacity Benefit Attainable With Intellidrive Technologies, Daiheng Ni, Jia Li, Steven Andrews, Haizhong Wang Sep 2010

Preliminary Estimate Of Highway Capacity Benefit Attainable With Intellidrive Technologies, Daiheng Ni, Jia Li, Steven Andrews, Haizhong Wang

Daiheng Ni

Recent development in IntelliDrive and associated Vehicular Ad Hoc Networks (VANET) has stimulated tremendous interests among decision-makers, practitioners, and researchers due to the potential safety and mobility benefits provided by these technologies. A primary concern regarding the deployment of IntelliDrive is degree of market penetration required for effectiveness. This paper proposes an approach to analyze the benefit of highway capacity gained from IntelliDrive. To fulfill this purpose, a model incorporating the effects of IntelliDrive on car following is formulated, based on which a rough estimate of the resulting capacity gain is derived. A simulation study is conducted to verify the …


Contact-Line Mechanics For Pattern Control, Guillaume Miquelard-Garnier, Andrew B. Croll, Chelsea S. Davis, Alfred Crosby Aug 2010

Contact-Line Mechanics For Pattern Control, Guillaume Miquelard-Garnier, Andrew B. Croll, Chelsea S. Davis, Alfred Crosby

Alfred Crosby

Wrinkled surfaces are ubiquitous in Nature and can be used in a large range of applications such as improved adhesives, microfluidic patterns, or as metrology instruments. Despite wide-ranging applications, existing methods do not permit local pattern control since all existing methods impose extensive compressive strains. In this article, we describe a new process that exploits the local deformation of a soft substrate as it stretches to form an adhesive interface with a thin polymer film. The wrinkle pattern is effectively a measurement of the strain-field created during the adhesion process, which shows a strong dependence on the speed of attachment. …


Spectral-Based Propagation Schemes For Time-Dependent Quantum Systems With Applications To Carbon Nanotubes, Eric Polizzi, Zuojing Chen Aug 2010

Spectral-Based Propagation Schemes For Time-Dependent Quantum Systems With Applications To Carbon Nanotubes, Eric Polizzi, Zuojing Chen

Eric Polizzi

Effective modeling and numerical spectral-based propagation schemes are proposed for addressing the challenges in time-dependent quantum simulations of systems ranging from atoms, molecules, and nanostructures to emerging nanoelectronic devices. While time-dependent Hamiltonian problems can be formally solved by propagating the solutions along tiny simulation time steps, a direct numerical treatment is often considered too computationally demanding. In this paper, however, we propose to go beyond these limitations by introducing high-performance numerical propagation schemes to compute the solution of the time-ordered evolution operator. In addition to the direct Hamiltonian diagonalizations that can be efficiently performed using the new eigenvalue solver FEAST, …


Draping Films: A Wrinkle To Fold Transition, Alfred Crosby, D. P. Holmes Jul 2010

Draping Films: A Wrinkle To Fold Transition, Alfred Crosby, D. P. Holmes

Alfred Crosby

A polymer film draping over a point of contact will wrinkle due to the strain imposed by the underlying substrate. The wrinkle wavelength is dictated by a balance of material properties and geometry; most directly the thickness of the draping film. At a critical strain, the stress in the film will localize, causing hundreds of wrinkles to collapse into several discrete folds. In this Letter, we examine the deformation of an axisymmetric sheet and quantify the force required to generate a fold. We observe that the energy of formation for a single fold scales nearly linearly with the film thickness. …


Cavitation Rheology Of The Vitreous: Mechanical Properties Of Biological Tissue, Jessica A. Zimberlin, Jennifer J. Mcmanus, Alfred Crosby Jun 2010

Cavitation Rheology Of The Vitreous: Mechanical Properties Of Biological Tissue, Jessica A. Zimberlin, Jennifer J. Mcmanus, Alfred Crosby

Alfred Crosby

We demonstrate the importance of measuring the mechanical properties of biological tissue in vivo by quantifying the mechanical properties of bovine vitreous both in its native state and upon removal from the eye. The mechanical properties are determined by the cavitation rheology technique developed in our labs to determine the linear modulus. This technique involves inducing a cavitation event at the tip of a syringe that is located at an arbitrary location within the vitreous sample. The pressure at which the cavitation event occurs can be directly related to the modulus. We show that the modulus decreases upon removal of …


Mechanistic Modelling Of Dynamic Mri Data Predicts That Tumour Heterogeneity Decreases Therapeutic Response, R Venkatasubramanian, Rb Arenas, Michael A. Henson, Ns Forbes Jun 2010

Mechanistic Modelling Of Dynamic Mri Data Predicts That Tumour Heterogeneity Decreases Therapeutic Response, R Venkatasubramanian, Rb Arenas, Michael A. Henson, Ns Forbes

Michael A Henson

BACKGROUND: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) contains crucial information about tumour heterogeneity and the transport limitations that reduce drug efficacy. Mathematical modelling of drug delivery and cellular responsiveness based on underutilised DCE-MRI data has the unique potential to predict therapeutic responsiveness for individual patients. METHODS: To interpret DCE-MRI data, we created a modelling framework that operates over multiple time and length scales and incorporates intracellular metabolism, nutrient and drug diffusion, trans-vascular permeability, and angiogenesis. The computational methodology was used to analyse DCE-MR images collected from eight breast cancer patients at Baystate Medical Center in Springfield, MA. RESULTS: Computer simulations …


Contact Angle Hysteresis: A Different View And A Trivial Recipe For Low Hysteresis Hydrophobic Surfaces, Joseph W. Krumpfer, Thomas J. Mccarthy May 2010

Contact Angle Hysteresis: A Different View And A Trivial Recipe For Low Hysteresis Hydrophobic Surfaces, Joseph W. Krumpfer, Thomas J. Mccarthy

Thomas J. McCarthy

Contact angle hysteresis is addressed from two perspectives. The first is an analysis of the events that occur during motion of droplets on superhydrophobic surfaces. Hysteresis is discussed in terms of receding contact line pinning and the tensile failure of capillary bridges. The sign of the curvature of the solid surface is implicated as playing a key role. The second is the report of a new method to prepare smooth low hysteresis surfaces. The thermal treatment of oxygen plasma-cleaned silicon wafers with trimethylsilyl-terminated linear poly(dimethylsiloxane) (PDMS - commercial silicone oils) in disposable glass vessels is described. This treatment renders silicon/silica …


Characterization Of Aggregate Size In Taxus Suspension Cell Culture, Martin E. Kolewe, Michael A. Henson, Susan C. Roberts May 2010

Characterization Of Aggregate Size In Taxus Suspension Cell Culture, Martin E. Kolewe, Michael A. Henson, Susan C. Roberts

Michael A Henson

Plant cells grow as aggregates in suspension culture, but little is known about the dynamics of aggregation, and no routine methodology exists to measure aggregate size. In this study, we evaluate several different methods to characterize aggregate size in Taxus suspension cultures, in which aggregate diameters range from 50 μm to 2000 μm, including filtration and image analysis, and develop a novel method using a specially equipped Coulter counter system. We demonstrate the suitability of this technology to measure plant cell culture aggregates, and show that it can be reliably used to measure total biomass accumulation compared to standard methods …


A Multiscale Model To Investigate Circadian Rhythmicity Of Pacemaker Neurons In The Suprachiasmatic Nucleus, Christina Vasalou, Michael A. Henson Mar 2010

A Multiscale Model To Investigate Circadian Rhythmicity Of Pacemaker Neurons In The Suprachiasmatic Nucleus, Christina Vasalou, Michael A. Henson

Michael A Henson

The suprachiasmatic nucleus (SCN) of the hypothalamus is a multicellular system that drives daily rhythms in mammalian behavior and physiology. Although the gene regulatory network that produces daily oscillations within individual neurons is well characterized, less is known about the electrophysiology of the SCN cells and how firing rate correlates with circadian gene expression. We developed a firing rate code model to incorporate known electrophysiological properties of SCN pacemaker cells, including circadian dependent changes in membrane voltage and ion conductances. Calcium dynamics were included in the model as the putative link between electrical firing and gene expression. Individual ion currents …


The Performance Of Wind Turbine Smart Rotor Control Approaches During Extreme Loads, Matthew Lackner, Gijs A. M. Van Kuik Feb 2010

The Performance Of Wind Turbine Smart Rotor Control Approaches During Extreme Loads, Matthew Lackner, Gijs A. M. Van Kuik

Matthew Lackner

Reducing the loads experienced by wind turbine rotor blades can lower the cost of energy of wind turbines. “Smart rotor control” concepts have emerged as a solution to reduce fatigue loads on wind turbines. In this approach, aerodynamic load control devices are distributed along the span of the blade, and through a combination of sensing, control, and actuation, these devices dynamically control the blade loads. While smart rotor control approaches are primarily focused on fatigue load reductions, extreme loads on the blades may also be critical in determining the lifetime of components, and the ability to reduce these loads as …


Floornet: Deployment And Evaluation Of Amultihop Wireless 802.11 Testbed, Pablo Serrano, Carlos J. Bernardos, Antonio De La Oliva, Albert Banchs, Ignacio Soto, Michael Zink Jan 2010

Floornet: Deployment And Evaluation Of Amultihop Wireless 802.11 Testbed, Pablo Serrano, Carlos J. Bernardos, Antonio De La Oliva, Albert Banchs, Ignacio Soto, Michael Zink

Michael Zink

A lot of attention has been given to multihop wireless networks lately, but further research—in particular, through experimentation—is needed. This attention has motivated an increase in the number of 802.11-based deployments, both indoor and outdoor. These testbeds, which require a significant amount of resources during both deployment and maintenance, are used to run measurements in order to analyze and understand the limitation and differences between analytical or simulation-based figures and the results from real-life experimentation. This paper makes two major contributions: (i) first, we describe a novel wireless multihop testbed, which we name FloorNet, that is deployed and operated under …


Electromechanically Driven Chaotic Dynamics Of Voids In Metallic Thin Films, Dimitrios Maroudas, M. R. Gungor, V. Tomar Jan 2010

Electromechanically Driven Chaotic Dynamics Of Voids In Metallic Thin Films, Dimitrios Maroudas, M. R. Gungor, V. Tomar

Dimitrios Maroudas

We report a systematic investigation of complex asymptotic states reached in the electromigration-driven morphological evolution of void surfaces in thin films of face-centered cubic metals with ⟨110⟩- and ⟨100⟩-oriented film planes under the simultaneous action of biaxial tension. The analysis is based on self-consistent dynamical simulations according to a realistic, well-validated, and fully nonlinear model. For ⟨110⟩-oriented film planes, we show that upon increasing the applied mechanical stress level, morphologically stable steady states transition to time-periodic states through a subcritical Hopf bifurcation. Further increase in the stress level triggers a sequence of period-doubling bifurcations that sets the driven nonlinear system …


Improved Utilization Of Biomass-Derived Carbon By Millisecond Co-Processing With Hydrogen Rich Feedstocks, Paul J. Dauenhauer, J. L. Colby, A. Bhan, L. D. Schmitt Jan 2010

Improved Utilization Of Biomass-Derived Carbon By Millisecond Co-Processing With Hydrogen Rich Feedstocks, Paul J. Dauenhauer, J. L. Colby, A. Bhan, L. D. Schmitt

Paul J. Dauenhauer

A reactor capable of improving the utilization of biomass-derived carbon during thermochemical conversion to synthesis gas is demonstrated experimentally. By co-processing hydrogen-deficient biomass (H/C[similar]2) with hydrogen-rich feedstocks (H/C≥4) through catalytic partial oxidation, 100% of the fuel carbon atoms fed to the reactor can be converted to CO.


Predicting Bite Force In Mammals: Two-Dimensional Versus Three-Dimensional Lever Models, Jl Davis, Se Santana, Er Dumont, Ir Grosse Jan 2010

Predicting Bite Force In Mammals: Two-Dimensional Versus Three-Dimensional Lever Models, Jl Davis, Se Santana, Er Dumont, Ir Grosse

Jeffrey M. Davis

Bite force is a measure of whole-organism performance that is often used to investigate the relationships between performance, morphology and fitness. When in vivo measurements of bite force are unavailable, researchers often turn to lever models to predict bite forces. This study demonstrates that bite force predictions based on two-dimensional (2-D) lever models can be improved by including three-dimensional (3-D) geometry and realistic physiological cross-sectional areas derived from dissections. Widely used, the 2-D method does a reasonable job of predicting bite force. However, it does so by over predicting physiological cross-sectional areas for the masseter and pterygoid muscles and under …


Kinetics Of Furfural Production By Dehydration Of Xylose In A Biphasic Reactor With Microwave Heating, George W. Huber, R. Weingarten, J. Cho, W. C. Conner Jr. Jan 2010

Kinetics Of Furfural Production By Dehydration Of Xylose In A Biphasic Reactor With Microwave Heating, George W. Huber, R. Weingarten, J. Cho, W. C. Conner Jr.

George W. Huber

In this paper we report a kinetic model for the dehydration of xylose to furfural in a biphasic batch reactor with microwave heating. There are four key steps in our kinetic model: (1) xylose dehydration to form furfural; (2) furfural reaction to form degradation products; (3) furfural reaction with xylose to form degradation products, and (4) mass transfer of furfural from the aqueous phase into the organic phase (methyl isobutyl ketone - MIBK). This kinetic model was used to fit experimental data collected in this study. The apparent activation energy for xylose dehydration is higher than the apparent activation energy …


Probing The Mechanism Of Silica Polymerization At Ambient Temperatures Using Monte Carlo Simulations, Peter A. Monson, Ateeque Malani, Scott M. Auerbach Jan 2010

Probing The Mechanism Of Silica Polymerization At Ambient Temperatures Using Monte Carlo Simulations, Peter A. Monson, Ateeque Malani, Scott M. Auerbach

Peter A. Monson

We have developed a model for silica polymerization at ambient temperatures and low densities and have studied this using reactive Monte Carlo simulations. The model focuses on SiO4 coordination with the energetics of hydrolysis and condensation reactions treated via the reaction ensemble. The simplicity of the model makes large system sizes accessible on a modest computation budget, although it is necessary to make additional assumptions in order to use the reactive Monte Carlo method as a simulation of the system dynamics. Excellent agreement for the evolution of the Qn distribution is obtained upon comparing the simulation results to experimental observations. …


Modeling Nanoparticle Formation During Early Stages Of Zeolite Growth: A Low-Coordination Lattice Model Of Template Penetration, Peter A. Monson, L. Jin, Scott M. Auerbach Jan 2010

Modeling Nanoparticle Formation During Early Stages Of Zeolite Growth: A Low-Coordination Lattice Model Of Template Penetration, Peter A. Monson, L. Jin, Scott M. Auerbach

Peter A. Monson

We present an extension of the simple-cubic lattice model developed by Jorge et al. [ J. Am. Chem. Soc. 2005, 127, 14388] of nanoparticle growth in the clear solution synthesis of silicalite-1 (MFI). We have implemented the model on a body-center cubic (bcc) lattice with second-neighbor repulsions, to generate a four-coordinate network that mimics the tetrahedral structure of silica. With this low-coordination lattice model we observe that the nanoparticles are metastable, possessing a core−shell structure with mostly silica in the core and templates forming a shell. Nanoparticle size is found to increase with temperature and decrease with solution pH, in …


Stabilization Of Thin Liquid Films Flowing Over Locally Heated Surfaces Via Substrate Topography, N Tiwari, Jm Davis Jan 2010

Stabilization Of Thin Liquid Films Flowing Over Locally Heated Surfaces Via Substrate Topography, N Tiwari, Jm Davis

Jeffrey M. Davis

A long-wave lubrication analysis is used to study the influence of topographical features on the linear stability of noninertial coating flows over a locally heated surface. Thin liquid films flowing over surfaces with localized heating develop a pronounced ridge at the upstream edge of the heater. This ridge becomes unstable to transverse perturbations above a critical Marangoni number and evolves into an array of rivulets even in the limit of noninertial flow. Similar fluid ridges form near topographical variations on isothermal surfaces, but these ridges are stable to perturbations. The influence of basic topographical features on the stability of the …


Apolar Ortho-Phenylene Ethynylene Oligomers: Conformational Ordering Without Intermolecular Aggregation, Jing Jiang, Morris M. Slutsky, Ticora V. Jones, Gregory N. Tew Jan 2010

Apolar Ortho-Phenylene Ethynylene Oligomers: Conformational Ordering Without Intermolecular Aggregation, Jing Jiang, Morris M. Slutsky, Ticora V. Jones, Gregory N. Tew

Gregory N. Tew

This paper describes the characterization of solvent induced folding behavior for non-polar (NP) alkoxy substituted ortho-phenylene ethynylene (o-PE) oligomers. Oligomers of lengths up to nine units have been shown to adopt helical conformations in heptane by NMR and CD spectroscopy, while chloroform promotes extended conformations. Surprisingly, the molar ellipticity values found in heptane for these oligomers are very small compared to other literature values of meta-phenylene ethynylene (m-PE) folded systems; however, comparable molar ellipticity values were found for a closed macrocyclic o-PE suggesting the weak ellipticity is a molecular-feature rather than a quality of folding indicator.


My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum Jan 2010

My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum

Otto Vogl

This document describes Otto Vogl's work in Italy. From 1975, Vogl served for 3 years as the Chairman of the Scientific Advisory Committee to the President Italo Trapasso of the Plastic Materials Company of Montedison SA, Milan, Italy. He was assigned to restructure the research activities and to organize the Research Division. He was responsible for the appointment of DiDrusco as the Vice President of Research and Paolo Galli as the Director of Research at the company’s facilities in Ferrara. Within a year of Vogl’s reorganization of the research organization the high yield catalyst for the polymerization of propylene was …


Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl Jan 2010

Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl

Otto Vogl

No abstract provided.


Scenario-Based Analysis Of Transportation Impacts In Case Of Dam Failure Flood Evacuation In Franklin County, Massachusetts (Paper # 10-1352), Haizhong Wang, Steven Andrews, John Collura, Daiheng Ni Jan 2010

Scenario-Based Analysis Of Transportation Impacts In Case Of Dam Failure Flood Evacuation In Franklin County, Massachusetts (Paper # 10-1352), Haizhong Wang, Steven Andrews, John Collura, Daiheng Ni

Daiheng Ni

Emergency planning is an important practice that allows government officials and planners to prepare for disasters and to make prompt response s that can save lives and property . One of the foremost concern s during an emergency is to save as many lives as possible. Thus, whethe r people can leave the disaster areas safely and efficiently is a prime consideration in emergency planning and management. Usually, transportation planners use a four - step model to predict sy s- tem - level performance regarding how people move from on e place to another , and to determine the network …


Representing The Fundamental Diagram: The Pursuit Of Mathematical Elegance And Empirical Accuracy (Paper # 10-1354), Haizhong Wang, Jia Li, Qian-Yong Chen, Daiheng Ni Jan 2010

Representing The Fundamental Diagram: The Pursuit Of Mathematical Elegance And Empirical Accuracy (Paper # 10-1354), Haizhong Wang, Jia Li, Qian-Yong Chen, Daiheng Ni

Daiheng Ni

The fundamental diagram, as the graphical representation of the relationships among traffic flow, speed, and density, has been the foundation of traffic flow theory and transportation engineering. 75 years after the seminal Greenshields model, a variety of models have been proposed to mathematically represent the speed-density relationship which underlies the fundamental diagram. Observed in these models was a clear path toward two competing goals: mathematical elegance and empirical accuracy. As the latest development of such a pursuit, this paper presents a family of speed-density models with varying numbers of parameters. All of these models perform satisfactorily and have physically meaningful …


Vehicular Ad Hoc Networks, Hossein Pishro-Nik, Shahrokh Valaee, Maziar Nekovee Jan 2010

Vehicular Ad Hoc Networks, Hossein Pishro-Nik, Shahrokh Valaee, Maziar Nekovee

Hossein Pishro-Nik

No abstract provided.