Engineering Commons^™

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

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

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 …

High Switching Endurance In TaoX Memristive Devices, Jianhua Yang, M Zhang, John Strachan, Feng Miao, Matthew Pickett, Ronald Kelley

Electrical and Computer Engineering Faculty Publication Series

We demonstrate over 1×1010 open-loop switching cycles from a simple memristive device stack of Pt/TaO��/Ta. We compare this system to a similar device stack based on titanium oxides to obtain insight into the solid-state thermodynamic and kinetic factors that influence endurance in metal-oxide memristors.

Tunable Band Gaps In Bilayer Graphene-Bn Heterostructures, Ashwin Ramasubramaniam, Doron Naveh, Elias Towe

Mechanical and Industrial Engineering Faculty Publication Series

We investigate band-gap tuning of bilayer graphene between hexagonal boron nitride sheets, by external electric fields. Using density functional theory, we show that the gap is continuously tunable from 0 to 0.2 eV, and is robust to stacking disorder. Moreover, boron nitride sheets do not alter the fundamental response from that of free-standing bilayer graphene, apart from additional screening. The calculations suggest that the graphene-boron nitride heterostructures could provide a viable route to graphene-based electronic devices.

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

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, …

High-Strength Wastewater Treatment By Microalgae, Xin Yuan

Environmental & Water Resources Engineering Masters Projects

Microalgae spontaneously convert CO2 and supplementary nutrients into biomass in the presence of light via photosynthesis, and at much higher rates than convention oil-producing crops. Algal biomass can then be transformed into methane via anaerobic bacteria-mediated fermentation, or to biodiesel via lipid extraction, as well as other byproducts of secondary metabolism. Production of biofuel by microalgae can be made more sustainable through coupling microalgal biomass production with existing power generation and wastewater treatment infrastructure. On the other hand, integration of algal biofuel production into wastewater treatment plant anaerobic digestion infrastructure has the potential to increase biogas production, decrease high and …

Two-Stage Filtration To Control Manganse And Dbps At The Lantern Hill Water Treatment Plant, Minh Pham

Environmental & Water Resources Engineering Masters Projects

This research involved full- and pilot-scale studies of treatment of the Aquarion Water Company (AWC) Lantern Hill groundwater source. With elevated levels of both dissolved manganese (~0.19 mg/L), dissolved iron (~1.9 mg/L) and natural organic matter (NOM) (~3 mg/L) the existing treatment plant is having difficulty in achieving required manganese removal while maintaining low concentrations of disinfection byproducts (DBPs) in finished water. At full-scale, dissolved manganese in the raw water is removed through pre-filter oxidation and adsorption on iron precipitates via application of free chlorine and permanganate as well as adsorption of dissolved manganese onto MnOx(s) coated filter media (anthracite …

Structure-Property Evolution During Polymer Crystallization, Deepak Arora

Open Access Dissertations

The main theme of this research is to understand the structure-property evolution during crystallization of a semicrystalline thermoplastic polymer. A combination of techniques including rheology, small angle light scattering, differential scanning calorimetry and optical microscopy are applied to follow the mechanical and optical properties along with crystallinity and the morphology. Isothermal crystallization experiments on isotactic poly-1-butene at early stages of spherulite growth provide quantitative information about nucleation density, volume fraction of spherulites and their crystallinity, and the mechanism of connecting into a sample spanning structure. Optical microscopy near the fluid-to-solid transition suggests that the transition, as determined by time-resolved mechanical …

Diffusion And Structure In Complex Fluids: I. Axial Diffusion In Membranes Ii. Proteins In Ionic Liquids, Malvika Bihari

Open Access Dissertations

Geometrically hindered motions of a single large solute (particle or polymer) can be imaged in real time via optical microscopy. The dynamics of fluorescent colloidal particles near surfaces and in porous membranes were monitored using confocal microscopy. A method of analysis to estimate diffusivity of particles in the axial direction by observing their intensity fluctuations was developed. The intensity fluctuations correspond to the Brownian motion of the particles in the axial direction. The method was successful in capturing the hindered diffusion of particles close to surfaces and in pores. This study provides a novel route to monitor the dynamics of …

Hole Mobility In Strained Ge And Iii-V P-Channel Inversion Layers With Self-Consistent Valence Subband Structure And High-K Insulators, Yan Zhang

Open Access Dissertations

We present a comprehensive investigation of the low-¯eld hole mobility in strained Ge and III-V (GaAs, GaSb, InSb and In1¡xGaxAs) p-channel inversion layers with both SiO2 and high-· insulators. The valence (sub)band structure of Ge and III-V channels, relaxed and under strain (tensile and compressive) is calculated using an effcient self-consistent method based on the six-band k ¢ p perturbation theory. The hole mobility is then computed using the Kubo-Greenwood formalism accounting for non-polar hole-phonon scattering (acoustic and optical), surface roughness scatter- ing, polar phonon scattering (III-Vs only), alloy scattering (alloys only) and remote phonon scattering, accounting for multi-subband dielectric …

Catalytic Fast Pyrolysis Of Biomass For The Production Of Fuels And Chemicals, Torren Ryan Carlson

Open Access Dissertations

Due to its low cost and large availability lignocellulosic biomass is being studied worldwide as a feedstock for renewable liquid biofuels. Currently there are several routes being studied to convert solid biomass to a liquid fuel, which involve multiple steps at long residence times thus greatly increasing the cost of biomass processing. Catalytic fast pyrolysis (CFP) is a new promising technology to convert directly solid biomass to gasoline-range aromatics that fit into the current infrastructure. CFP involves the rapid heating of biomass (~500˚C sec-1) in an inert atmosphere to intermediate temperatures (400 to 600 ˚C) in the presence of zeolite …

Bench-Scale Assessment Of Low Pressure Membrane Fouling: Characterization And Examination The Role Of Organic Nitrogen Compounds, Anh Hai Nguyen

Open Access Dissertations

The primary goal of this research was to improve understanding of the fouling of low pressure hollow fiber membranes used in drinking water treatment. The major difference of this study compared to other reported studies was the use of a hollow fiber membrane module at operating conditions mimicking those of full-scale practice. Two poly(vinylidene-fluoroethylene) based hollow fiber membranes (A and B) were tested. Different types of fouling indices (total, hydraulic irreversible, chemical irreversible) developed based on a resistance in series model were used to assess membrane performance. Data from bench-scale and full-scale plants were compared to validate the use of …

Stochastic Modeling Of The Equilibrium Speed-Density Relationship, Haizhong Wang

Open Access Dissertations

Fundamental diagram, a graphical representation of the relation among traffic flow, speed, and density, has been the foundation of traffic flow theory and transportation engineering for many years. For example, the analysis of traffic dynamics relies on input from this fundamental diagram to find when and where congestion builds up and how it dissipates; traffic engineers use a fundamental diagram to determine how well a highway facility serves its users and how to plan for new facilities in case of capacity expansion. Underlying a fundamental diagram is the relation between traffic speed and density which roughly corresponds to drivers’ speed …

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

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

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

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, …

Diffusion Of Adhesion Layer Metals Controls Nanoscale Memristive Switching, Jianhua Yang, John Strachan, Qiangfei Xia, Douglas Ohlberg, Philip Kuekes, Ronald Kelley, William Stickle, Duncan Stewart, Gilberto Medeiros-Ribeiro,, R Stanley Williams

Electrical and Computer Engineering Faculty Publication Series

Thermal diffusion of Ti through Pt electrode forms Ti atom channels of 1 nm diameter along Pt grain boundaries, seeding switching centers and controlling nanoscale memristive switching. The image shows EFTEM maps of Ti overlaid on HRTEM images for a Si/SiO2 100 nm/Ti 5nm/Pt 15 nm sample in-situ annealed in ultrahigh vacuum at 250 °C for 1 hour.

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

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

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

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 …

Regenerating Spent Zeolites With Uv And Uv/H2o2 To Enhance Removal Of Endocrine Disrupting Compounds, Safina Singh

Environmental & Water Resources Engineering Masters Projects

Endocrine disrupting compounds (EDCs) have become contaminants of emerging concern due to their potential for harmful effects on human and ecological health, at low concentrations (ppb). As an alternative to conventional adsorption media, activate carbon, this study investigates feasibility of using high-silica, hydrophobic zeolites for the removal of EDCs through adsorption process. Zeolites are crystalline, porous alumino-silicate with well defined pore structures, and tetrahedral framework.

While traditional media regeneration processes are energy and cost intensive, evidence has been found that zeolites can be regenerated multiple times through relatively inexpensive methods using direct ultraviolet (UV) photolysis and advanced oxidation process (AOP). …

On Detection, Analysis And Characterization Of Transient And Parametric Failures In Nano-Scale Cmos Vlsi, Alodeep Sanyal

Open Access Dissertations

As we move deep into nanometer regime of CMOS VLSI (45nm node and below), the device noise margin gets sharply eroded because of continuous lowering of device threshold voltage together with ever increasing rate of signal transitions driven by the consistent demand for higher performance. Sharp erosion of device noise margin vastly increases the likelihood of intermittent failures (also known as parametric failures) during device operation as opposed to permanent failures caused by physical defects introduced during manufacturing process. The major sources of intermittent failures are capacitive crosstalk between neighbor interconnects, abnormal drop in power supply voltage (also known as …

Western Woburn Greenway Study, Jennifer H. Masters, Bryan C. Aldeghi, Eric C. Kells, Maureen C. Pollock, Rebekah Lynne Decourcey, Carol Waag, Youjin Kwon, Kathryn E. Ostermier, Patrick T. Mcgeough, Ryan Patrick Ball

Landscape Architecture & Regional Planning Studio and Student Research and Creative Activity

In spring 2010, the Department of Landscape Architecture and Regional Planning at the University of Massachusetts Amherst was asked to complete a landscape planning study, the “Western Woburn Greenway Study” for the City of Woburn, MA. The study was undertaken by a team of graduate students, supervised by Professor Jack Ahern. The goals of that study are as follows.

The City of Woburn currently has two large parcel groups of undeveloped land, Whispering Hill (the north focus area) and Winning/Shannon Farms (the south focus area) that are, or may become, available for acquisition (see “Scope of Project” below). The first …

Prediction And Manipulation Of Drop Size Distribution Of Emulsions Using Population Balance Equation Models For High-Pressure Homogenization, Neha B. Raikar

Open Access Dissertations

Emulsions constitute a wide range of natural as well as processed products. Pharmaceutical applications of emulsions include oral administration, parenteral delivery, ophthalmic medicine, topical and transdermal creams, and fluorocarbon-in-water emulsions for blood oxygenation. In the foods area many of the products like mayonnaise, margarine, ice-creams are emulsions by nature and some products can also be used for delivery of active ingredients (e.g. nutraceuticals) with potential health benefits. Emulsions are also encountered at many stages of petroleum recovery, transportation, and processing. Typically, emulsions are manufactured in a two-step process. First a coarse emulsion called a premix is made which is passed …

Diversifying The Internet, Yong Liao

Open Access Dissertations

Diversity is a widely existing and much desired property in many networking systems. This dissertation studies diversity problems in Internet, which is the largest computer networking system in the world. The motivations of diversifying the Internet are two-fold. First, diversifying the Internet improves the Internet routing robustness and reliability. Most problems we have encountered in our daily use of Internet, such as service interruptions and service quality degradation, are rooted in the inter-domain routing system of Internet. Inter-domain routing is policy-based routing, where policies are often based on commercial agreements between ASes. Although people know how to safely accommodate a …

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 …