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Portland State University

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2019

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Articles 61 - 74 of 74

Full-Text Articles in Engineering

The Tides They Are A-Changin’: A Comprehensive Review Of Past And Future Nonastronomical Changes In Tides, Their Driving Mechanisms And Future Implications, Ivan D. Haigh, Mark D. Pickering, J.A. Mattias Green, Brian K. Arbic, Arne Arns, Soenke Dangendorf, David Hill, David A. Jay, Multiple Additional Authors Jan 2019

The Tides They Are A-Changin’: A Comprehensive Review Of Past And Future Nonastronomical Changes In Tides, Their Driving Mechanisms And Future Implications, Ivan D. Haigh, Mark D. Pickering, J.A. Mattias Green, Brian K. Arbic, Arne Arns, Soenke Dangendorf, David Hill, David A. Jay, Multiple Additional Authors

Civil and Environmental Engineering Faculty Publications and Presentations

Scientists and engineers have observed for some time that tidal amplitudes at many locations are shifting considerably due to non-astronomical factors. Here we review comprehensively these important changes in tidal properties, many of which remain poorly understood. Over long geological time-scales, tectonic processes drive variations in basin size, depth, and shape, and hence the resonant properties of ocean basins. On shorter geological time-scales, changes in oceanic tidal properties are dominated by variations in water depth. A growing number of studies have identified widespread, sometimes regionally-coherent, positive and negative trends in tidal constituents and levels during the 19th, 20th and early …


Plasma-Enhanced Chemical Vapor Deposition Of Acetylene On Codeposited Bimetal Catalysts Increasing Graphene Sheet Continuity Under Low-Temperature Growth Conditions, Joshua Tracy, Otto Zietz, Samuel Olson, Jun Jiao Jan 2019

Plasma-Enhanced Chemical Vapor Deposition Of Acetylene On Codeposited Bimetal Catalysts Increasing Graphene Sheet Continuity Under Low-Temperature Growth Conditions, Joshua Tracy, Otto Zietz, Samuel Olson, Jun Jiao

Mechanical and Materials Engineering Faculty Publications and Presentations

Here, we report a novel method for low-temperature synthesis of monolayer graphene at 450 °C on a polycrystalline bimetal Ni-Au catalyst. In this study, low-temperature chemical vapor deposition synthesis of graphene was performed at 450 °C on codeposited Ni-Au which shows successful monolayer graphene formation without an extra annealing process. The experimental results suggest that electron beam codeposition of bimetal catalyst is the key procedure that enables the elimination of the pre-growth high-temperature annealing of the catalyst prior to graphene synthesis, an indispensable process, used in previous reports. The formation was further improved by plasma-assisted growth in which the inductively …


Technological Cooperation Network In Biotechnology Analysis Of Patents With Brazil As The Priority Country, Cristiano Goncalves Pereira, Rodrigo Ribeiro Da Silva, Joao Ricardo Lavoie, Geciane Silveira Porto Jan 2019

Technological Cooperation Network In Biotechnology Analysis Of Patents With Brazil As The Priority Country, Cristiano Goncalves Pereira, Rodrigo Ribeiro Da Silva, Joao Ricardo Lavoie, Geciane Silveira Porto

Engineering and Technology Management Faculty Publications and Presentations

Purpose – The establishment of partnerships between companies, government and universities aims to enhance innovation and the technological development of institutions. The biotechnology sector has grown in recent years mainly driven by its cooperative business model. Compared to other countries, this sector is slowly advancing in Brazil, with delays in science, technology and innovation, especially in the private sector. This paper aims to examine, through social network analysis, the collaborative networks between institutions that filed patents in biotechnology – medicinal preparations from plants – whose inventions had Brazil as the priority country. Design/methodology/approach – The study of technological cooperation using …


Benchmarking And Evaluating The Efficiency Of Mass Transit Systems Based On Best Practice Using Data Envelopment Analysis, Jacqueline Nayame, Maoloud Dabab, Timothy Anderson Jan 2019

Benchmarking And Evaluating The Efficiency Of Mass Transit Systems Based On Best Practice Using Data Envelopment Analysis, Jacqueline Nayame, Maoloud Dabab, Timothy Anderson

Engineering and Technology Management Faculty Publications and Presentations

Public transit systems in the USA have been faced with mounting pressure to decrease their operating costs while at the same time expected to increase ridership and meeting multiple societal needs. The primary objective of this study is to measure the efficiencies of mass transit agencies based on best practice in the US, identify the influencing factors leading to their efficiencies, and how these strategies and policies can be used improve inefficiency in transit agencies. Using Data Envelopment Analysis (DEA) method, the study analyzed the mass performance of 334 transit agencies across the US using data from the national transit …


Cybersecurity Planning For Artificial Intelligent Systems In Space, Gary Langford, Lucas Beaulieu, Jeffery Carpenter, Ian Watkins, Brock Marsh, Teah Heidorn, Chris Chase Jan 2019

Cybersecurity Planning For Artificial Intelligent Systems In Space, Gary Langford, Lucas Beaulieu, Jeffery Carpenter, Ian Watkins, Brock Marsh, Teah Heidorn, Chris Chase

Engineering and Technology Management Faculty Publications and Presentations

CubeSats continue to proliferate and are an excellent low-cost method of remote sensing. A key piece of intelligent systems is sensory input, data storage, and data communications. With the continued miniaturization of technology, CubeSats will increase their sensory inputs with future miniaturization and enhance their robustness for autonomous operations if data and communications are secure. These futures inspire an intelligent system solution to on-orbit communications. This paper explores a dual-microprocessor approach to improve hardware cybersecurity of intelligent systems, with a view toward intensional intelligence as a means of adjudicating access to sensitive data onboard the CubeSat. With enhanced cybersecurity, Artificial …


Capital Efficiency For Development Stage Biotech-Based Firms: An Ipo Perspective, Mark J. Ahn, Amir Shaygan Jan 2019

Capital Efficiency For Development Stage Biotech-Based Firms: An Ipo Perspective, Mark J. Ahn, Amir Shaygan

Engineering and Technology Management Faculty Publications and Presentations

Access to multiple tranches of capital is critical for predominantly no revenue development stage biotech firms. While financing needs are monotonically increasing over multiple years in the product development approval cycle, the market for high risk, milestone driven biotech investment is significantly more volatile than the financial markets as a whole. In this paper, we analyzed the role and relative importance of global biotech IPOs, as well as other sources of capital such as strategic alliances, for research and development funding. We also explored and assessed the degree of mismatch between the access to capital, operational efficiencies, and how firms …


Accumulation Of Di-2-Ethylhexyl Phthalate From Polyvinyl Chloride Flooring Into Settled House Dust And The Effect On The Bacterial Community, Samantha Velazquez, Chenyang Bi, Jeff Kline, Susie Nunez, Richard Corsi, Ying Xu, Suzanne L. Ishaque Jan 2019

Accumulation Of Di-2-Ethylhexyl Phthalate From Polyvinyl Chloride Flooring Into Settled House Dust And The Effect On The Bacterial Community, Samantha Velazquez, Chenyang Bi, Jeff Kline, Susie Nunez, Richard Corsi, Ying Xu, Suzanne L. Ishaque

Mechanical and Materials Engineering Faculty Publications and Presentations

Di-2-ethylhexyl phthalate (DEHP) is a plasticizer used in consumer products and building materials, including polyvinyl chloride flooring material. DEHP adsorbs from material and leaches into soil, water, or dust and presents an exposure risk to building occupants by inhalation, ingestion, or absorption. A number of bacterial isolates are demonstrated to degrade DEHP in culture, but bacteria may be susceptible to it as well, thus this study examined the relation of DEHP to bacterial communities in dust. Polyvinyl chloride flooring was seeded with homogenized house dust and incubated for up to 14 days, and bacterial communities in dust were identified at …


Neuromechanical Model Of Rat Hindlimb Walking With Two-Layer Cpgs, Kaiyu Deng, Nicholas Szczecinski, Dirk Arnold, Emanuel Andrada, Martin Fischer, Roger Quinn, Alexander J. Hunt Jan 2019

Neuromechanical Model Of Rat Hindlimb Walking With Two-Layer Cpgs, Kaiyu Deng, Nicholas Szczecinski, Dirk Arnold, Emanuel Andrada, Martin Fischer, Roger Quinn, Alexander J. Hunt

Mechanical and Materials Engineering Faculty Publications and Presentations

This work demonstrates a neuromechanical model of rat hindlimb locomotion undergoing nominal walking with perturbations. In the animal, two types of responses to perturbations are observed: resetting and non-resetting deletions. This suggests that the animal locomotor system contains a memory-like organization. To model this phenomenon, we built a synthetic nervous system that uses separate rhythm generator and pattern formation layers to activate antagonistic muscle pairs about each joint in the sagittal plane. Our model replicates the resetting and non-resetting deletions observed in the animal. In addition, in the intact (i.e., fully afferented) rat walking simulation, we observe slower recovery after …


Performance Of Plunge Depth Control Methods During Friction Stir Welding, Jinyoung Yoon, Cheolhee Kim, Sehun Rhee Jan 2019

Performance Of Plunge Depth Control Methods During Friction Stir Welding, Jinyoung Yoon, Cheolhee Kim, Sehun Rhee

Mechanical and Materials Engineering Faculty Publications and Presentations

Friction stir welding is a preferred solid state welding process for Al/Fe joints, and in friction stir lap welding, the plunge depth is the most critical parameter for joint strength. We compared three plunge depth control methods, namely conventional position control, offset position control, and deflection compensation control in the friction stir lap welding of 3 mm-thick Al 5083-O alloy over 1.2 mm-thick DP 590 steel. The desired plunge depth was 0.2 mm into the steel sheet. However, the pin did not reach the steel surface under conventional position control due to deflection of the vertical axis of the welding …


Improvement Of The Tribological Characteristics Of Aisi 8620, 8640 And 52100 Steels Through Thermo-Reactive Treatments, Rafael Magalhães Triani, Fábio Edson Mariani, Lucas Fuscaldi De Assis Gomes, Pedro Gabriel Bonella De Oliveira, George E. Totten, Luiz Carlos Casteletti Jan 2019

Improvement Of The Tribological Characteristics Of Aisi 8620, 8640 And 52100 Steels Through Thermo-Reactive Treatments, Rafael Magalhães Triani, Fábio Edson Mariani, Lucas Fuscaldi De Assis Gomes, Pedro Gabriel Bonella De Oliveira, George E. Totten, Luiz Carlos Casteletti

Mechanical and Materials Engineering Faculty Publications and Presentations

The production of vanadium and niobium carbides (VC and NbC) layers on AISI 8620, 8640, and 52100 steels may increase hardness and wear resistance of substrates. Thermochemical treatments were performed at 1000 °C for 2 and 4 h. The characterization of the treated samples was carried out by means of Knoop microhardness tests, “calotest” type microadhesive wear test, layer adhesion test according to VDI 3198 standard, and X-ray diffraction. Compact and uniform layers of VC and NbC were obtained in all treatments, with hardness up to 2500 HK and microadhesive wear resistance far superior to that of the substrates, indicating …


Overview Of Homechem: House Observations Of Microbial And Environmental Chemistry, Delphine K. Farmer, Marina E. Vance, Jon P. D. Abbatt, Andrew Abeleira, Michael R. Alves, Richard Corsi, Peter F. Decarlo, Allen H. Goldstein, Vicki H. Grassian, Lea Hildebrandt Ruiz, Jose L. Jimenez, Tara Kahan, Multiple Additional Authors Jan 2019

Overview Of Homechem: House Observations Of Microbial And Environmental Chemistry, Delphine K. Farmer, Marina E. Vance, Jon P. D. Abbatt, Andrew Abeleira, Michael R. Alves, Richard Corsi, Peter F. Decarlo, Allen H. Goldstein, Vicki H. Grassian, Lea Hildebrandt Ruiz, Jose L. Jimenez, Tara Kahan, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

The House Observations of Microbial and Environmental Chemistry (HOMEChem) study is a collaborative field investigation designed to probe how everyday activities influence the emissions, chemical transformations and removal of trace gases and particles in indoor air. Sequential and layered experiments in a research house included cooking, cleaning, variable occupancy, and window-opening. This paper describes the overall design of HOMEChem and presents preliminary case studies investigating the concentrations of reactive trace gases, aerosol particles, and surface films. Cooking was a large source of VOCs, CO2, NOx, and particles. By number, cooking particles were predominantly in the ultrafine mode. Organic aerosol dominated …


A High Torque Density Halbach Rotor Coaxial Magnetic Gear, Ho Yin Wong, Jonathan Z. Bird, David Barnett, Wesley Williams Jan 2019

A High Torque Density Halbach Rotor Coaxial Magnetic Gear, Ho Yin Wong, Jonathan Z. Bird, David Barnett, Wesley Williams

Electrical and Computer Engineering Faculty Publications and Presentations

This paper presents the design, analysis, and experimental testing results for a 5.67:1 Halbach rotor magnetic gearbox with a ferromagnetic back support. Using 3-D finite element analysis software the Halbach magnetic gearbox was calculated to achieve a volumetric torque density of 284N·m/L with only an active region outer diameter of 120mm. The experimental prototype obtained an active region volumetric torque density of 261.4N·m/L


Machine-Learning Based Three-Qubit Gate For Realization Of A Toffoli Gate With Cqed-Based Transmon Systems, Sahar Daraeizadeh, Shavindra Premaratne, Xiaoyu Song, Marek A. Perkowski, Anne Y. Matsuura Jan 2019

Machine-Learning Based Three-Qubit Gate For Realization Of A Toffoli Gate With Cqed-Based Transmon Systems, Sahar Daraeizadeh, Shavindra Premaratne, Xiaoyu Song, Marek A. Perkowski, Anne Y. Matsuura

Electrical and Computer Engineering Faculty Publications and Presentations

We use machine learning techniques to design a 50 ns three-qubit flux-tunable controlled-controlled-phase gate with fidelity of >99.99% for nearest-neighbor coupled transmons in circuit quantum electrodynamics architectures. We explain our gate design procedure where we enforce realistic constraints, and analyze the new gate’s robustness under decoherence, distortion, and random noise. Our controlled-controlled phase gate in combination with two single-qubit gates realizes a Toffoli gate which is widely used in quantum circuits, logic synthesis, quantum error correction, and quantum games.


Design And Evaluation Of A Non-Contact Bed-Mounted Sensing Device For Automated In-Home Detection Of Obstructive Sleep Apnea: A Pilot Study, Clara Mosquera-Lopez, Joseph Leitschuh, John Condon, Chad C. Hagen, Uma Rajhbeharrysingh, Cody Hanks, Peter Jacobs Jan 2019

Design And Evaluation Of A Non-Contact Bed-Mounted Sensing Device For Automated In-Home Detection Of Obstructive Sleep Apnea: A Pilot Study, Clara Mosquera-Lopez, Joseph Leitschuh, John Condon, Chad C. Hagen, Uma Rajhbeharrysingh, Cody Hanks, Peter Jacobs

Electrical and Computer Engineering Faculty Publications and Presentations

We conducted a pilot study to evaluate the accuracy of a custom built non-contact pressure-sensitive device in diagnosing obstructive sleep apnea (OSA) severity as an alternative to in-laboratory polysomnography (PSG) and a Type 3 in-home sleep apnea test (HSAT). Fourteen patients completed PSG sleep studies for one night with simultaneous recording from our load-cell-based sensing device in the bed. Subjects subsequently installed pressure sensors in their bed at home and recorded signals for up to four nights. Machine learning models were optimized to classify sleep apnea severity using a standardized American Academy of Sleep Medicine (AASM) scoring of the gold …