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2013

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Articles 181 - 210 of 7289

Full-Text Articles in Engineering

Sociallink: A Social Network Based Trust System For P2p File Sharing Systems, Fang Qi Dec 2013

Sociallink: A Social Network Based Trust System For P2p File Sharing Systems, Fang Qi

All Theses

In peer-to-peer (P2P) file sharing systems, many autonomous peers without preexisting trust relationships share files with each other. Due to their open environment and distributed structure, these systems are vulnerable to the significant impact from selfish and misbehaving nodes. Free-riding, whitewash, collusion and Sybil attacks are common and serious threats, which severely harm non-malicious users and degrade the system performance. Many trust systems were proposed for P2P file sharing systems to encourage cooperative behaviors and punish non-cooperative behaviors. However, querying reputation values usually generates latency and overhead for every user. To address this problem, a social network based trust system …

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Friction And Wear Of Polytetrafluoroethylene/Graphene Oxide Composite Thin Films, Justin Kyle Carter Dec 2013

Friction And Wear Of Polytetrafluoroethylene/Graphene Oxide Composite Thin Films, Justin Kyle Carter

Graduate Theses and Dissertations

Polytetrafluoroethylene (PTFE) is a commonly used solid lubricant due to its low coefficient of friction and chemical inertness. As a polymer, PTFE suffers from high wear and low adhesion to substrates limiting its use as a thin film. Thin PTFE films are ideal candidates for solid lubrication in micro-machines and bearing applications. The main goal of this work is to enhance the durability of thin PTFE films through the addition of few layered graphene oxide (GO) as filler. In order to address adhesion issues, the addition of an adhesive layer of polydopamine (PDA) between stainless steel substrates and thin PTFE …

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Crack Growth Behavior Under Creep-Fatigue Conditions Using Compact And Double Edge Notch Tension-Compression Specimens, Santosh B. Narasimha Chary Dec 2013

Crack Growth Behavior Under Creep-Fatigue Conditions Using Compact And Double Edge Notch Tension-Compression Specimens, Santosh B. Narasimha Chary

Graduate Theses and Dissertations

The American Society for Testing and Materials (ASTM) has recently developed a new standard for creep-fatigue crack growth testing, E 2760-10, that supports testing compact specimens, C(T), under load controlled conditions. C(T) specimens are commonly used for fatigue and creep-fatigue crack growth testing under constant-load-amplitude conditions. The use of these specimens is limited to positive load ratios. They are also limited in the amount of crack growth data that can be developed at high stress intensity values due to accumulation of plastic and/or creep strains leading to ratcheting in the specimen. Testing under displacement control can potentially address these shortcomings …

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Assessing Trichloromethane Formation And Control In Algal-Stimulated Waters Amended With Nitrogen And Phosphorus, Clinton Mash Dec 2013

Assessing Trichloromethane Formation And Control In Algal-Stimulated Waters Amended With Nitrogen And Phosphorus, Clinton Mash

Graduate Theses and Dissertations

Nitrogen (N) and phosphorus (P) enrichments can stimulate algal growth in drinking water sources, which can cause increased production of disinfection byproduct (DBP) precursors. However, the effect of systematic N and P enrichments on DBP formation and control has not been adequately studied. In this work, we enriched samples from a drinking water source - sampled on April 5, May 30, and August 19, 2013 - with N and P to stimulate algal growth at N:P ratios covering almost five orders of magnitude (0.2-4,429). To simulate DBP-precursor removal processes at drinking water treatment plants (DWTPs), the samples were treated with …

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Assessing The Impact Of Chlorine Residual On Trihalomethane And Haloacetonitrile Formation Under Chlorination And Chloramination Disinfection Regimes, Thien Duc Do Dec 2013

Assessing The Impact Of Chlorine Residual On Trihalomethane And Haloacetonitrile Formation Under Chlorination And Chloramination Disinfection Regimes, Thien Duc Do

Graduate Theses and Dissertations

A disinfection byproduct (DBP) formation potential (FP) test can be used to indirectly measure the concentration of DBP precursors in natural waters, permitting assessment of various DBP-related treatment processes and control strategies. While these tests require a 7-day chlorine residual (CR) between 3-5 mg L-1 as Cl2, it is not well known if this recommended residual corresponds to the true DBPFP (i.e., the maximum concentrations) for trihalomethanes (THMs) and haloacetonitriles (HANs). In this study, THMs and HANs were quantified as a function of CR under three common disinfection regimes: (1) free chlorine at pH 7.0 (FC7), (2) …

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Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason G. Vogeler Dec 2013

Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason G. Vogeler

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Polycarbonate (PC) is a tough, transparent engineering thermoplastic. Its impact strength and ability undergo large plastic deformations without shatter make PC an ideal protective material for impact-resilient eyewear, aircraft windows and transparent armor. A good understanding of the response of this material to large deformations at high strain rates is critical for its utilization in these applications. To this end, a striker-less Kolsky bar device is employed in this work for the needed material characterization. The apparatus allow impulsive torsion and/or compression loadings with pulse durations sufficiently long for the plastic flow behavior to develop fully. Three new testing techniques …

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A Study On Countermeasures Against Steganography: An Active Warden Approach, Qilin Qi Dec 2013

A Study On Countermeasures Against Steganography: An Active Warden Approach, Qilin Qi

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

Digital steganography is a method used for hiding information in digital images. It can be used for secure communication. There have been many robust digital steganography methods invented in recent decades. The steganographic message can be inserted in multimedia cover signal such as audio, image and video. However, this technique also may be used by malicious users to transmit dangerous information through the Internet beyond the control of security agencies. How to detect and/or block potentially dangerous information transmission on the Internet through billions of multimedia files while not affecting innocent multimedia communications becomes a challenging problem. Existing steganalysis methods …

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Application Of Image Processing And Finite Element Analysis In Modeling Chloride Diffusion In Concrete, Arash Razmjoo Dec 2013

Application Of Image Processing And Finite Element Analysis In Modeling Chloride Diffusion In Concrete, Arash Razmjoo

All Dissertations

Utilizing numerical simulation models to predict the long-term mechanical and transport behavior of concrete structures is becoming increasingly popular. The majority of these models have been developed using laboratory test data that consider concrete as a homogeneous material with spherical aggregates. These models could not be a represented of real concrete because it has no primitive shaped aggregate besides that the porosity size and distribution varies from point to point. In this study a novel method for more accurate prediction of the chloride diffusion in concrete was developed. A general framework of the quantitative computed tomography (QCT) and finite element …

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Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason Gerald Vogeler Dec 2013

Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason Gerald Vogeler

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Polycarbonate (PC) is a tough, transparent engineering thermoplastic. Its impact strength and ability undergo large plastic deformations without shatter make PC an ideal protective material for impact-resilient eyewear, aircraft windows and transparent armor. A good understanding of the response of this material to large deformations at high strain rates is critical for its utilization in these applications. To this end, a striker-less Kolsky bar device is employed in this work for the needed material characterization. The apparatus allow impulsive torsion and/or compression loadings with pulse durations sufficiently long for the plastic flow behavior to develop fully. Three new testing techniques …

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Au-Based Core-Shell Nanoparticles For Direct Formic Acid Fuel Cells, Chiajen Hsu Dec 2013

Au-Based Core-Shell Nanoparticles For Direct Formic Acid Fuel Cells, Chiajen Hsu

Material Science and Engineering Dissertations - Archive

Unique Au/Pd core-shell nanoparticles were synthesized via galvanic replacement of Cu by Pd on hollow Au nanoparticles. Au/PtCu core-shell nanoparticles were also synthesized using this method. These core-shell nanoparticles exhibited unique electrochemical properties - the Au/Pd nanoparticles demonstrated superior electrochemical activity for formic acid oxidation and the Au/PtCu nanoparticles improved the kinetics in oxygen reduction reaction, when compared to their corresponding pure metal particles. In this dissertation, we aim at investigating catalytic abilities of these core-shell nanoparticles and understanding electrochemical reactions in direct formic acid fuel cells.Different Pd thicknesses on hollow Au nanoparticles in the core-shell configuration have been investigated. …

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Grain Structure Evolution Of Tin-Based Lead-Free Solder Joints In Electronic Packaging Assembly And Its Impact On The Fatigue Reliability, Huili Xu Dec 2013

Grain Structure Evolution Of Tin-Based Lead-Free Solder Joints In Electronic Packaging Assembly And Its Impact On The Fatigue Reliability, Huili Xu

Material Science and Engineering Dissertations - Archive

Solder is one of the main joints materials used in the electronics for decades of years. It is not only the mechanical support but also conducts the electric signals in the electronics. However, the regulation of lead content in electronic devices has driven the transition from lead-tin solder to the lead-free solder that requires lots of research to fill the knowledge gap in the lead-free solder property. At the same time, the reliability issues due to solder failure are of great interest as the miniaturization and mobilization trend of the electronic devices continues. A lot of works have been done …

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Bubble Template Synthesis Of Hollow Gold Nanoparticle, Chivarat Muangphat Dec 2013

Bubble Template Synthesis Of Hollow Gold Nanoparticle, Chivarat Muangphat

Material Science and Engineering Dissertations - Archive

Recently, a new synthesis method for creating hollow gold nanoparticles by using electrochemically hydrogen nanobubbles as a template was discovered in our research group. Hollow gold nanoparticles with well-controlled, tunable dimension and morphology can be synthesized using various synthesis conditions. Such hollow gold nanoparticles exhibit unique optical properties that can be tuned by changing the nanoparticle structures. The objective of this study is to understand the formation mechanism of hollow gold nanoparticles synthesized using bubble template synthesis method. The synthesis process can be divided into two main processes: the formation of hydrogen nanobubble and the reduction of gold ions on …

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The Effects Of Microstructure On The Mechanical Properties Of Hard Transition Metal Silicon Nitride Nanocomposite Coatings, Jessica Mooney Dec 2013

The Effects Of Microstructure On The Mechanical Properties Of Hard Transition Metal Silicon Nitride Nanocomposite Coatings, Jessica Mooney

Material Science and Engineering Dissertations - Archive

In this body of work, the examination of two different transition metal silicon nitride (MeSiN) systems using two different methods of physical vapor deposition (PVD) allowed for the development of a detailed understanding between the processing conditions, the micro-scale and nano-scale morphology, and the mechanical properties of the as-deposited thin film nanocomposite coatings. TiSiN coatings processed using the high-energy Arc deposition technique had hardness values of up to 33.6 GPa, and a previously unidentified (TiSi)N FCC crystalline phase, likely present due to the amounts of energy employed during coating processing, was discovered via intensive low angle X-Ray diffraction (XRD) and …

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Pavement Evaluation Of The Concrete Tie-Bars And Dowel Baskets On Irvin Cobb Drive, Us 60, Mccracken County, Ky, Brad W. Rister, Jamie Creech, Joe Whelan, Timothy R. B. Taylor Dec 2013

Pavement Evaluation Of The Concrete Tie-Bars And Dowel Baskets On Irvin Cobb Drive, Us 60, Mccracken County, Ky, Brad W. Rister, Jamie Creech, Joe Whelan, Timothy R. B. Taylor

Kentucky Transportation Center Research Report

A 1500 Mhz. ground coupled, ground penetrating radar antenna was used to identify both the horizontal alignment and the vertical displacement of the concrete tie-bars and the transverse joint dowel bar assembles on a Portland-Cement-Concrete-Pavement (PCCP) on US 60 in McCracken County, KY. Approximately 5 lanes miles of PCCP were evaluated using the 1500 Mhz. ground coupled antenna. Results indicate that only one transverse dowel basket out of an approximate total of 1,760 were within 4.17 inches of the pavement surface. Seven transverse dowel baskets were misaligned four inches or greater from the location of the sawed joint. These areas …

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On The Biophysics And Kinetics Of Toehold-Mediated Dna Strand Displacement, Bernard Yurke Dec 2013

On The Biophysics And Kinetics Of Toehold-Mediated Dna Strand Displacement, Bernard Yurke

Electrical and Computer Engineering Faculty Publications and Presentations

Dynamic DNA nanotechnology often uses toehold-mediated strand displacement for controlling reaction kinetics. Although the dependence of strand displacement kinetics on toehold length has been experimentally characterized and phenomenologically modeled, detailed biophysical understanding has remained elusive. Here, we study strand displacement at multiple levels of detail, using an intuitive model of a random walk on a 1D energy landscape, a secondary structure kinetics model with single base-pair steps and a coarse-grained molecular model that incorporates 3D geometric and steric effects. Further, we experimentally investigate the thermodynamics of three-way branch migration. Two factors explain the dependence of strand displacement kinetics on toehold …

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Tascked: The Sanity Promoting Task Manager, Jake Tobin Dec 2013

Tascked: The Sanity Promoting Task Manager, Jake Tobin

Computer Science and Software Engineering

Personal task managers or various forms of to-do lists are abundant in our modern computing age. With the explosion of mobile computing technology, it is easier than ever to take notes digitally and make the data seemingly instantly available anywhere on the Internet. There is a fairly well defined core set of features in personal task managers available for public consumption, but it seems nothing that is publicly available provides feedback to the user or suggestions based on user history. Tascked is a task management solution, which records user history and solicits user feedback on progress. This allows the system …

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Testing Virtual Machines For Cadrc Server Hosting, Robin Verweij Dec 2013

Testing Virtual Machines For Cadrc Server Hosting, Robin Verweij

Computer Science and Software Engineering

No abstract provided.

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Scitech Book News Reviews, Susan Fingerman Dec 2013

Scitech Book News Reviews, Susan Fingerman

Sci-Tech News

No abstract provided.

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Broadcasting With Prediction And Selective Forwarding In Vehicular Networks, Jainjun Yang, Zongming Fei Dec 2013

Broadcasting With Prediction And Selective Forwarding In Vehicular Networks, Jainjun Yang, Zongming Fei

Computer Science Faculty Publications

Broadcasting in vehicular networks has attracted great interest in research community and industry. Broadcasting on disseminating information to individual vehicle beyond the transmission range is based on inter-vehicle communication systems. It is crucial to broadcast messages to other vehicles as fast as possible because the messages in vehicle communication systems are often emergency messages such as accident warning or alarm. In many current approaches, the message initiator or sender selects the node among its neighbors that is farthest away from it in the broadcasting direction and then assigns the node to rebroadcast the message once the node gets out of …

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Development And Verification Of A Test System To Quantify Strain Of An Optical Displacement Indicator And The Design Of A Strain Indicating Prototype, Josh Lake Dec 2013

Development And Verification Of A Test System To Quantify Strain Of An Optical Displacement Indicator And The Design Of A Strain Indicating Prototype, Josh Lake

All Theses

The organic-rich Middle Devonian Marcellus Shale of the Appalachian basin is a rapidly developing natural gas play. Stratigraphic boundaries of the Marcellus Shale in Westmoreland County, Pennsylvania were identified using geophysical logs from 10 vertical gas-producing wells in a 23 sq. km area. Gamma-ray, bulk density, and resistivity well logs were examined to assess hydrocarbon potential. Values of porosity, total organic carbon (TOC), and water saturation (SW) were derived and mapped by incorporating well-log data into Marcellus-specific formulas. Gamma-ray, penetration (minutes per foot drilled), and mud-logging gas (total gas) from 12 horizontal wells from within the study area were also …

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A Probabilistic Analysis Of Islanding Effects In A Modeled Distribution System With Renewable Resources, Paul Gooding Dec 2013

A Probabilistic Analysis Of Islanding Effects In A Modeled Distribution System With Renewable Resources, Paul Gooding

All Theses

For this research, an investigation was undertaken regarding the inclusion of renewable resources into the distribution system. This incorporated the increasing prevalence of solar and wind resources, as well as the development of islanding capabilities within distribution systems.

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Establishing Key Performance Indicators To Measure The Benefit Of Introducing The Facilities Manager At An Early Stage In The Building Information Modelling Process, Barry Mcauley Dec 2013

Establishing Key Performance Indicators To Measure The Benefit Of Introducing The Facilities Manager At An Early Stage In The Building Information Modelling Process, Barry Mcauley

Conference papers

The Facilities Manager occupies a unique position within the lifecycle of a building asset, as he/she is one of the only AEC / FM professionals who is in a position to view the product of the entire design and build process and, is responsible for the operational phase which incurs approximately five times the initial capital cost. Despite the potential benefits that the Facilities Manager offers, this profession still does not command the recognition it deserves within the AEC/FM sector. This is beginning to change through the introduction of Building Information Modelling (BIM). In order for the BIM process to …

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Cost And Embodied Energy Optimization Of Rectangular Reinforced Concrete Beams, Alexander Kosloski Dec 2013

Cost And Embodied Energy Optimization Of Rectangular Reinforced Concrete Beams, Alexander Kosloski

All Theses

Concrete has a large environmental footprint so it is desirable to find ways to efficiently design structural members. Engineers can exercise their abilities early on in the design phase of construction projects to reduce the environmental footprint by minimizing the amount of materials required. One way to achieve these results is to optimize the design of structural concrete. In this study, simple-span rectangular reinforced concrete (RC) beams with a range of different bending moments were analyzed. The primary goal was to combine life cycle analysis (LCA), numerical optimization, and reinforced concrete mechanics to create a framework for designing efficient RC …

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Physics Trick - Balanced Can, Said Shakerin Dec 2013

Physics Trick - Balanced Can, Said Shakerin

All Faculty Articles - School of Engineering and Computer Science

The ordinary 12-oz beverage cans in the figures below are not held up with any props or glue. The bottom of such cans is stepped at its circumference for better stacking. When this kind of can is tilted, as shown in Fig. 1, the outside corners of the step touch the surface beneath, providing an effective contact about 1 cm wide. Because the contact is relatively wide and the geometry is symmetrical, it is easy to balance an empty can by simply adding an appropriate amount of water so that the overall center of mass is located directly above the …

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Design And Development Of A Low-Cost Handheld Picoammeter, Malcolm Stagg Dec 2013

Design And Development Of A Low-Cost Handheld Picoammeter, Malcolm Stagg

Honors Capstones

No abstract provided.

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The Effects Of Wrist Orthoses On The Stiffness Of Wrist Rotations, Daniel Brad Seegmiller Dec 2013

The Effects Of Wrist Orthoses On The Stiffness Of Wrist Rotations, Daniel Brad Seegmiller

Theses and Dissertations

Wrist orthoses are the most common upper limb orthoses, being used by thousands of individuals each year to stabilize, immobilize, or support the wrist joint. Wrist orthoses achieve their function by altering the stiffness of the wrist joint (Figure 1-1). However, there is no quantitative understanding of how wrist orthoses affect wrist stiffness, and consequently, wrist orthosis development often relies on feel, intuition, or empirical heuristics rather than a methodical, quantitative approach. Because wrist movement control is dominated by wrist joint stiffness (Charles and Hogan 2011) a quantitative understanding of how wrist orthoses alter the stiffness of the wrist is …

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Proteins In High Electric Fields, David Michael Landry Dec 2013

Proteins In High Electric Fields, David Michael Landry

Theses and Dissertations

Being able to control protein function directly and in real time is attractive. In this thesis, I discuss controlling protein activity using alternating current electric fields on the order of 1 MV/m. Since protein structures result in localized and/or protein-wide charge gradients, it is expected that a sufficiently high electric field applied across a protein should result in structural distortions which can temporarily alter or halt protein function. The field is set to oscillate above the influences of the electrochemical double layer effects (1 kHz) and below the level needed for hydrodynamic rotation of proteins (10 MHz). A device is …

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Raman Spectroscopic Investigation Of Chondroitinase Abc Treatment After Spinal Cord Injury In An Organotypic Model, Shane Ruberto Dec 2013

Raman Spectroscopic Investigation Of Chondroitinase Abc Treatment After Spinal Cord Injury In An Organotypic Model, Shane Ruberto

Theses - ALL

This study investigated (1) the ability of an organotypic model of spinal cord injury (SCI) to recapitulate significant pathobiological events of in vivo SCI from a Raman spectroscopic perspective, and (2) the Raman spectroscopic effects of chondroitinase ABC (cABC) treatment on said model of SCI. Tissue from mouse spinal cords was excised, sectioned, and placed into culture, before being systematically injured to induce trauma. Cultures with and without cABC treatment were assessed using Raman spectroscopy at varying times post-injury. We demonstrate that Raman spectral phenomena characteristic of SCI can be observed using an organotypic model. By comparing these phenomena with …

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A Physicochemical Evaluation Of The Compressibility And Dewatering Behavior Of Dredged Sediments, George F. Segré Dec 2013

A Physicochemical Evaluation Of The Compressibility And Dewatering Behavior Of Dredged Sediments, George F. Segré

Theses - ALL

The dewatering of low percent solids wastes from tailings ponds, harbors, and waterways presents a challenge in the U.S. and abroad, given the vast amounts that need to be dewatered annually. The United Stated Corps of Engineers estimate about 8.5x109 ft3 of dredged sediments are removed annually in order to keep waterways functional. Dewatering may be achieved with the aid of high strength synthetic textiles, such as geotextiles, which may be sewn lengthwise to form a geotextile tube. Typically, dredged material is mixed with flocculants such as polyacrylamide (PAM), and then pumped into geotextile tubes. In doing so, the flocculants …

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Subway Rail Car Filter Sampling Tool, Brian Hong, Julia Pollard, Philip Ybarra Dec 2013

Subway Rail Car Filter Sampling Tool, Brian Hong, Julia Pollard, Philip Ybarra

Mechanical Engineering

The following design report has been prepared by Team Slice for both Cal Poly’s Mechanical Engineering Department and Lawrence Livermore National Laboratory. This report provides an overview of the design ideation process of creating a subway rail car filter sampling tool. This cutting tool will take samples of HVAC filters from subway railcars in New York City, NY. These samples will then be used for processing in biological terror emergency response situations. This device will provide an easy, safe, and user friendly tool to cut filter samples. The current method of cutting is a pair of scissors or shears, which …

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