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Full-Text Articles in Engineering

Autonomous Wall-Climbing Robots For Inspection And Maintenance Of Concrete Bridges, Jizhong Xiao Aug 2018

Autonomous Wall-Climbing Robots For Inspection And Maintenance Of Concrete Bridges, Jizhong Xiao

INSPIRE-UTC Annual Meetings

Since 2002, the PI’s group has developed four generations of wall-climbing robots for NDE inspection of civil infrastructure. These robots combine the advantages of aerodynamic attraction and suction to achieve a desirable balance of strong adhesion and high mobility. They don’t require perfect sealing and can thus move on smooth and rough surfaces, such as brick, concrete, stucco, wood, glass, and metal. For example, Rise-Rover uses two drive modules to carry their middle compartment with payload up to 450 N. Ground penetrating radar (GPR)-Rover and Mini GPR-Rover are custom designed to carry a GSSI’s GPR antenna for subsurface defect detection …


Climbing Robots With Automated Deployment Of Sensors And Nde Devices For Steel Bridge Inspection, Hung La Aug 2018

Climbing Robots With Automated Deployment Of Sensors And Nde Devices For Steel Bridge Inspection, Hung La

INSPIRE-UTC Annual Meetings

The PI was a research scientist/faculty at Rutgers University who successfully developed in 2014 a Robotic Assisted Bridge Inspection Tool (RABIT) for bridge deck inspections. Other bridge elements, such as girders and columns, or even underside of bridge decks are difficult to access and remain a challenge for efficient inspection. Like visual inspection, current practices for bridge maintenance are equally time consuming and expensive. Automation of simple maintenance actions such as bearing cleaning and concrete sealing with robots will lead to a leap forward to the next-generation strategy of bridge maintenance.

This project aims to develop and prototype automated climbing …


Mobile-Manipulating Uavs For Sensor Installation, Bridge Inspection And Maintenance, Paul Oh Aug 2018

Mobile-Manipulating Uavs For Sensor Installation, Bridge Inspection And Maintenance, Paul Oh

INSPIRE-UTC Annual Meetings

Mobile manipulating UAVs have great potential for bridge inspection and maintenance. Since 2002, the PI has developed UAVs that could fly through in-and-around buildings and tunnels. Collision avoidance in such cluttered near-Earth environments has been a key challenge. The advent of light-weight, computationally powerful cameras led to breakthroughs in SLAM even though SLAM-based autonomous aerial navigation around bridges remains an unsolved problem.

In 2007, the PI integrated a mobile manipulation function into UAVs, greatly extending the capabilities of UAVs from passive survey of environments with cameras to active interaction with environments using limbs. Mobile-manipulating UAVs have since been demonstrated to …


Quantitative Bridge Inspection Ratings Using Autonomous Robotic Systems, Anil Agrawal Aug 2018

Quantitative Bridge Inspection Ratings Using Autonomous Robotic Systems, Anil Agrawal

INSPIRE-UTC Annual Meetings

The 2001 study sponsored by FHWA raised serious concern on the consistency and reliability of visual inspection. Although consistent ratings can be obtained with a good QA/QC program, based on a recent study by the PI, the concern for reliability of defect detection remains. With the adoption of the recent AASHTO Manuel for Bridge Element Inspection, the new inspection approach not only requires rating for bridge elements, but also the location and extent of deterioration. Since autonomous robotic systems generate an enormous amount of inspection data, deducing from the data to a simple rating along with the location and extent …


Hyperspectral Image Analysis For Mechanical And Chemical Properties Of Concrete And Steel Surfaces, Genda Chen Aug 2018

Hyperspectral Image Analysis For Mechanical And Chemical Properties Of Concrete And Steel Surfaces, Genda Chen

INSPIRE-UTC Annual Meetings

A typical human eye will respond to wavelengths from approximately 400 to 700 nm. A hyperspectral camera can extend the wavelength to as high as 2500 nm. This extension will allow engineers to find objects, identify materials, and detect processes on structural surface, which cannot be done with visual inspection.

This project aims to develop an open-source catalogue of concrete and steel surfaces and their spectral/spatial features (discoloration, characteristic wavelength, roughness, texture, shape, etc.), extract spatial/spectral features of hyperspectral images, and develop/train a multi-class classification or regression classifier through machine learnings (supervised and/or semi-supervised), and validate the classifier as a …


3d Microwave Camera For Concrete Delamination And Steel Corrosion Detection, R. Zoughi Aug 2018

3d Microwave Camera For Concrete Delamination And Steel Corrosion Detection, R. Zoughi

INSPIRE-UTC Annual Meetings

Corrosion of embedded steel reinforcement in concrete leads to concrete cracking and delamination, followed by increased salt and moisture permeation and further damage. Invisibility of the embedded rebar in combination with physical inaccessibility in elevated bridges presents a challenge in the assessment of RC bridge elements. Wideband (3D) microwave synthetic aperture radar (SAR) imaging techniques that can be integrated into a UAV offer a practical solution to overcome this challenge.

This project aims to develop and optimize a 3D microwave camera for bridge inspection on a UAV platform, quantify its performance for steel corrosion evaluation and concrete delamination detection in …


Thermally-Stable Passive Antenna Sensor For Strain And Crack Monitoring, Dan Li, Yang Wang Aug 2018

Thermally-Stable Passive Antenna Sensor For Strain And Crack Monitoring, Dan Li, Yang Wang

INSPIRE-UTC Annual Meetings

An RFID patch antenna sensor can be used to wirelessly measure the strain and/or crack on a structural surface through the shift of its electromagnetic resonance frequency. According to electromagnetic theory, the resonance frequency �R of a patch antenna has an approximately linear relationship with strain �: [Formula]

Previous design of antenna sensor with Rogers RT/duroid® 5880 substrate is sensitive to temperature change. A new RFID patch antenna sensor with thermally-stable substrate material Rogers RT/duroid® 6202 is designed and tested through both numerical simulation and laboratory experiments. A new RFID chip with much smaller footprint is adopted in the …


Deep Semantic 3d Visual Metric Reconstruction Using Wall-Climbing Robot, Liang Yang, Bing Li, Yong Chang, Jizhong Xiao Aug 2018

Deep Semantic 3d Visual Metric Reconstruction Using Wall-Climbing Robot, Liang Yang, Bing Li, Yong Chang, Jizhong Xiao

INSPIRE-UTC Annual Meetings

This project introduces an inspection method using a deep neural network to detect the crack and spalling defects on concrete structures performed by a wall-climbing robot. First, we create a pixel-level semantic dataset which includes 820 labeled images. Second, we propose an inspection method to obtain 3D metric measurement by using an RGB-D camera-based visual simultaneous localization and mapping (SLAM), which is able to generate pose coupled key-frames with depth information. Therefore, the semantic inspection results can be registered in the concrete structure 3D model for condition assessment and monitoring. Third, we present our new generation wall-climbing robot to perform …


Modeling Hose Dynamics For Unmanned Aerial Vehicles, Blake Hament, Paul Y. Oh, Autonomous Systems Lab (Dasl) Aug 2018

Modeling Hose Dynamics For Unmanned Aerial Vehicles, Blake Hament, Paul Y. Oh, Autonomous Systems Lab (Dasl)

INSPIRE-UTC Annual Meetings

Bridges and other large pieces of infrastructure accumulate massive amounts of dirt, dust, and other particulates that can obscure the structure when scanning to discern structural integrity. Traditionally, these particulates have been removed by humans operating handheld compressed-air hoses, often while mounting ladders -- a risky and inefficient task. To improve infrastructure scanning, unmanned aerial vehicles (UAV) equipped with hoses could be used to clean the structure in place of the current method.

The challenge in equipping a UAV with a hose is compensating for the reaction forces and torques produced by fluids expelled by the hose. In order to …


Parallel Manipulator-Gripper For Mobile Manipulating Uavs, Dongbin Kim, Paul Y. Oh, Autonomous Systems Lab (Dasl) Aug 2018

Parallel Manipulator-Gripper For Mobile Manipulating Uavs, Dongbin Kim, Paul Y. Oh, Autonomous Systems Lab (Dasl)

INSPIRE-UTC Annual Meetings

Unmanned Aerial Vehicles (UAVs) are originally developed for military, but have been developed over time to time for valuable roles in surveillance, work-assistant, and intelligence for both civilian and military operations.

The ability of UAVs that manipulate or carry objects can expand the type of tasks achieved by unmanned aerial systems. High degree of freedom robots with dexterous arm can lead to various applications. Most of manipulators are serial, each motor on each joint affects on stabilizing UAVs. Our lab , DASL , has presented parallel mechanism manipulator for UAVs. It results in less impact on center of gravity(CoG) of …


Integrated Fiber Optic Sensors For Strain, Temperature And Corrosion-Induced Mass Loss Measurement, Chuanrui Guo, Liang Fan, Genda Chen Aug 2018

Integrated Fiber Optic Sensors For Strain, Temperature And Corrosion-Induced Mass Loss Measurement, Chuanrui Guo, Liang Fan, Genda Chen

INSPIRE-UTC Annual Meetings

In this study, a fiber optic sensing system based on long period fiber gratings (LPFG) in LP06 and LP07 modes is designed, fabricated and tested for simultaneous measurements of strain, temperature and corrosion-induced mass loss. It consists of three steel tubes and several Fe-C coated LPFG sensors for long- and short-term corrosion monitoring, respectively, when deployed in proximity and parallel to a steel member. Graphene/silver nanowire (Gr/AgNW) composite was coated on the LPFG surface for efficient Fe-C electroplating due to its high optical transparency and conductivity. The sensor was subjected to both tensile strain and temperature, and submerged in 3.5 …


Bridge Resilience Assessment With Inspire Data, Yijian Albert Zhang, Reginald Desroches, Iris Tien Aug 2018

Bridge Resilience Assessment With Inspire Data, Yijian Albert Zhang, Reginald Desroches, Iris Tien

INSPIRE-UTC Annual Meetings

In this research, we proposed analytical models validated with numerical results to assess how inspection-collected data on corrosion can be used to update bridge models and predict performance under future events. A detailed investigation of the vulnerability of bridges due to corrosion at both component and global levels. The results show the impact of corrosion-induced degradation on the seismic fragility of reinforced concrete columns under various failure modes, e.g., flexural, shear, and lap-spliced failures. As increasing amounts of data are collected on the states of bridges, the results show how these data can be used to update bridge assessments and …


Microwave Imaging For Corroded Rebars And Delamination In Concrete Structures, Matthew Dvorsky, Stephon Barker, Mohammad Tayeb Ahmad Ghasr, R. Zoughi Aug 2018

Microwave Imaging For Corroded Rebars And Delamination In Concrete Structures, Matthew Dvorsky, Stephon Barker, Mohammad Tayeb Ahmad Ghasr, R. Zoughi

INSPIRE-UTC Annual Meetings

Corrosion of embedded steel reinforcement bars (rebars) in concrete leads to concrete cracking and delamination, which in turn leads to increased salt and moisture permeation and further damage. This study aims to evaluate the effectiveness of microwave imaging for the characterization of this corrosionand delaminationof steel rebar embedded in concrete.


Hyperspectral Image Analysis For Mechanical And Chemical Properties Of Concrete And Steel Surfaces, Liang Fan, Paul Manley, Huaishuai Shang, Abdullah Alhaj, Hongyan Ma, Genda Chen Aug 2018

Hyperspectral Image Analysis For Mechanical And Chemical Properties Of Concrete And Steel Surfaces, Liang Fan, Paul Manley, Huaishuai Shang, Abdullah Alhaj, Hongyan Ma, Genda Chen

INSPIRE-UTC Annual Meetings

According to the 2017 ASCE Report Card, 39% and 15% of 614,387 bridges in the U.S. are more than 50 years and 40 to 49 years, respectively. The number of deficient bridges is increasing. One of the most common causes of reinforced concrete deterioration is corrosion of steel reinforcing bars. Currently, most bridges are visually inspected every two years using boom/snooper trucks to get access to various areas to be inspected. The subjective visual inspection often leads to inconsistent results that are less useful in bridge management. Hyperspectral camera, installed on an unmanned aerial vehicle, can potentially supplement visual inspection …


Uav-Enabled Measurement On Magnetic Field Of Smart Rocks For Bridge Scour Monitoring, Haibin Zhang, Zhaochao Li, Genda Chen Aug 2018

Uav-Enabled Measurement On Magnetic Field Of Smart Rocks For Bridge Scour Monitoring, Haibin Zhang, Zhaochao Li, Genda Chen

INSPIRE-UTC Annual Meetings

Scour and other hydraulic induced failures accounted for 58% of over 1,500 bridge collapses in the U.S. Bridge scour is the engineering term for the erosion of soil surrounding a bridge foundation as a result of water current. Monitoring with fixed and/or portable instrumentations is one of the most effective measures in mitigating scour hazards. However, fixed instrumentation with sensors installed prior to flood events cannot detect scour other than the area instrumented. It is susceptible to the harsh environment during a flood event. Portable instrumentation is difficult to deploy during a severe flood event due to safety consideration and/or …


Battery-Free Antenna Sensors For Strain And Crack Monitoring Of Bridge Structures, Yang Wang Aug 2018

Battery-Free Antenna Sensors For Strain And Crack Monitoring Of Bridge Structures, Yang Wang

INSPIRE-UTC Annual Meetings

Fatigue cracks need to be monitored in fatigue critical elements. Previous research by the PI produced a radiofrequency identification (RFID) sensor prototype that can accurately measure tens of micro-strains in laboratory. The antenna sensor was made on a glass microfiber-reinforced polymer substrate. Although accurate for strain measurement and detection of fatigue cracks, the sensor performs less satisfactorily in field conditions since the substrate material (RT/duroid® 5880) is susceptible to thermal effect. In addition, a wireless interrogation distance by a general-purpose commercial RFID reader is limited to the order of meter, which is not desirable with the operation of a UAV. …


Uav-Enabled Measurement For Spatial Magnetic Field Of Smart Rocks In Bridge Scour Monitoring, Genda Chen Aug 2018

Uav-Enabled Measurement For Spatial Magnetic Field Of Smart Rocks In Bridge Scour Monitoring, Genda Chen

INSPIRE-UTC Annual Meetings

Foundation scour is the main cause of bridge collapses in the U.S. In 2011, the principal investigator (PI) proposed smart rocks with embedded magnets for bridge scour monitoring. Once deployed around a bridge pier, smart rocks as field agents offer mission-critical information about the maximum depth of a scour hole developed around the bridge foundation – the key parameter that is used to assess foundation stability in engineering design and retrofit. Smart rocks have recently been deployed and tested at three bridge sites in California and Missouri. With multiple measurements, they can be located with an accuracy of 0.5 m. …


Arrayed Lyser And Homogenizer Systems With Multiple Agitator Devices, Robert W. Doebler, Mark Brown, Tanya Ferguson, Bruce Irvine, James D. Sterling Aug 2018

Arrayed Lyser And Homogenizer Systems With Multiple Agitator Devices, Robert W. Doebler, Mark Brown, Tanya Ferguson, Bruce Irvine, James D. Sterling

Business and Information Technology Faculty Research & Creative Works

Systems and methods for the efficient agitation of tissue samples. A device may include a plurality of chambers that each receives samples therein. The plurality of chambers may be uniformly spaced with respect to a least one dimension, to form a one dimensional or two-dimensional array. Each of the chambers may include an opening and an agitator device in fluid contact with the sample disposed within the chamber. The agitator devices may include a micromotor which provides rotational motion to a shaft and an impeller fixed to the shaft such that the impeller and the shaft rotate together upon provision …


Node-Based Resilience Measure Clustering With Applications To Noisy And Overlapping Communities In Complex Networks, John Matta, Tayo Obafemi-Ajayi, Jeffrey Borwey, Koushik Sinha, Donald C. Wunsch, Gunes Ercal Aug 2018

Node-Based Resilience Measure Clustering With Applications To Noisy And Overlapping Communities In Complex Networks, John Matta, Tayo Obafemi-Ajayi, Jeffrey Borwey, Koushik Sinha, Donald C. Wunsch, Gunes Ercal

Electrical and Computer Engineering Faculty Research & Creative Works

This paper examines a schema for graph-theoretic clustering using node-based resilience measures. Node-based resilience measures optimize an objective based on a critical set of nodes whose removal causes some severity of disconnection in the network. Beyond presenting a general framework for the usage of node-based resilience measures for variations of clustering problems, we experimentally validate the usefulness of such methods in accomplishing the following: (i) clustering a graph in one step without knowing the number of clusters a priori; (ii) removing noise from noisy data; and (iii) detecting overlapping communities. We demonstrate that this clustering schema can be applied successfully …


Insights Into Low Salinity Water Flooding, Hasan N. Al-Saedi, Ralph E. Flori, Patrick V. Brady Aug 2018

Insights Into Low Salinity Water Flooding, Hasan N. Al-Saedi, Ralph E. Flori, Patrick V. Brady

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

In our previous work, we examined the potential of divalent cations (Mg2+ and Ca2+) in formation water (FW) for low-salinity (LS) EOR effect, where the increase in divalent cations in FW lowered the impact of LS water EOR.

In this paper, we demonstrate the importance of the same divalent cations in the injected water (both FW and LS water). We also try to relate the percentage of the divalent cations in the injected water to that in the FW to engineer the optimum concentration of the injected water and obtain the maximum oil recovery from sandstone reservoirs. …


High-Resolution Qpf Uncertainty And Its Implications For Flood Prediction: A Case Study For The Eastern Iowa Flood Of 2016, Bong Chul Seo, Felipe Quintero, Witold F. Krajewski Aug 2018

High-Resolution Qpf Uncertainty And Its Implications For Flood Prediction: A Case Study For The Eastern Iowa Flood Of 2016, Bong Chul Seo, Felipe Quintero, Witold F. Krajewski

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study addresses the uncertainty of High-Resolution Rapid Refresh (HRRR) quantitative precipitation forecasts (QPFs), which were recently appended to the operational hydrologic forecasting framework. In this study, we examine the uncertainty features of HRRR QPFs for an Iowa flooding event that occurred in September 2016. Our evaluation of HRRR QPFs is based on the conventional approach of QPF verification and the analysis of mean areal precipitation (MAP) with respect to forecast lead time. The QPF verification results show that the precipitation forecast skill of HRRR significantly drops during short lead times and then gradually decreases for further lead times. The …


A Framework For Estimating Immediate Interdependent Functionality Reduction Of A Steel Hospital Following A Seismic Event, Emad M. Hassan, Hussam Mahmoud Aug 2018

A Framework For Estimating Immediate Interdependent Functionality Reduction Of A Steel Hospital Following A Seismic Event, Emad M. Hassan, Hussam Mahmoud

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Functionality of an infrastructure is its ability to provide its intended services. Maintaining an acceptable level of infrastructure functionality, particularly for critical infrastructure, following an extreme event is vital for effective community recovery. Estimating functionality depends on proper quantification of losses, which requires accurate assessment of infrastructure damage. The damage is presented in the form of fragility functions that are generally developed using nonlinear finite element analysis. To date, no study has been conducted to assess the effect of modeling approach on seismic fragilities of an infrastructure, the associated losses, and functionality reduction. In addition, existing frameworks for estimating functionality …


A New Approach To Measure Soil Shrinkage Curve, Lin Li, Xiong Zhang Aug 2018

A New Approach To Measure Soil Shrinkage Curve, Lin Li, Xiong Zhang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The shrinkage curve is widely used to characterize soil deformation during drying. Over the years, several methods have been developed to measure soil shrinkage curves. However, these methods suffered from several limitations and were rarely used because of difficulties in accurate soil volume measurement during drying. In this study, a simple method is proposed to measure soil shrinkage curves. The soil volume is measured using a photogrammetric technique from which a three-dimensional (3D) model of the soil specimen during drying can be accurately reconstructed. The soil volume is calculated based on the reconstructed 3D model. Meanwhile, a digital balance is …


Nanometer Ultrastructural Brain Damage Following Low Intensity Primary Blast Wave Exposure, Hailong Song, Landry M. Konan, Jiankun Cui, Catherine E. Johnson, Graham K. Hubler, Ralph G. Depalma, Zezong Gu Aug 2018

Nanometer Ultrastructural Brain Damage Following Low Intensity Primary Blast Wave Exposure, Hailong Song, Landry M. Konan, Jiankun Cui, Catherine E. Johnson, Graham K. Hubler, Ralph G. Depalma, Zezong Gu

Mining Engineering Faculty Research & Creative Works

Blast-induced mild traumatic brain injury (mTBI) is of particular concern among military personnel due to exposure to blast energy during military training and combat. The impact of primary low-intensity blast mediated pathophysiology upon later neurobehavioral disorders has been controversial. Developing a military preclinical blast model to simulate the pathophysiology of human blast injury is an important first step. This article provides an overview of primary blast effects and perspectives of our recent studies demonstrating ultrastructural changes in the brain and behavioral disorders resulting from open-field blast exposures up to 46.6 kPa using a murine model. The model is scalable and …


Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 2, A Quasi-Static Thermo-Mechanical Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Ronald B. Rogge, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle Aug 2018

Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 2, A Quasi-Static Thermo-Mechanical Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Ronald B. Rogge, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The additive manufacturing (AM) process metal powder bed fusion (PBF) can quickly produce complex parts with mechanical properties comparable to that of wrought materials. However, thermal stress accumulated during Metal PBF may induce part distortion and even cause failure of the entire process. This manuscript is the second part of two companion manuscripts that collectively present a part-scale simulation method for fast prediction of thermal distortion in Metal PBF. The first part provides a fast prediction of the temperature history in the part via a thermal circuit network (TCN) model. This second part uses the temperature history from the TCN …


Thermal And Mechanical Response Of Inner Cone Sample Of Zrb₂-Sic Ceramic Under Arc-Jet Conditions, Jun Wei, Lokeswarappa R. Dharani, K. Chandrashekhara Aug 2018

Thermal And Mechanical Response Of Inner Cone Sample Of Zrb₂-Sic Ceramic Under Arc-Jet Conditions, Jun Wei, Lokeswarappa R. Dharani, K. Chandrashekhara

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Under arc-jet test conditions, ZrB2-SiC ceramic will undergo high temperature oxidation and develop an external glassy layer (SiO2), zirconia sub-layer (ZrO2) and SiC-depleted diboride layer (ZrB2). This study relates to finite element modeling of the effects of oxidation on heat transfer and mechanical behavior of ZrB2-SiC ceramic under arc-jet test conditions. A steady-state heat transfer FE method was employed to conduct the heat transfer analysis to obtain the temperature distribution in the inner body of the cone. The surface thermal conditions available in the literature were used in the heat …


Generation Of Transverse Photo-Induced Voltage In Plasmonic Metasurfaces Of Triangle Holes, Marjan Akbari, Jie Gao, Xiaodong Yang Aug 2018

Generation Of Transverse Photo-Induced Voltage In Plasmonic Metasurfaces Of Triangle Holes, Marjan Akbari, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We experimentally and numerically demonstrate the transverse electrical response produced by circularly-polarized light with normal incidence observed as transverse photoinduced voltage across the plasmonic metasurface made of triangle holes. The measured transverse photo-induced voltage is consistent with the calculated acting force on electrons in the metasurface by using the Maxwell's stress tensor. The polarity of voltage reverses as the incident spin (light helicity) switches from right-handed circular polarization to left-handed circular polarization. The origin of the spin-dependent voltage sign is the broken symmetries of the electric and magnetic fields in the triangle hole due to the opposite circular polarizations. The …


Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 1, A Thermal Circuit Network Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle Aug 2018

Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 1, A Thermal Circuit Network Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The additive manufacturing (AM) process metal powder bed fusion (PBF) can quickly produce complex parts with mechanical properties comparable to wrought materials. However, thermal stress accumulated during PBF induces part distortion, potentially yielding parts out of specification and frequently process failure. This manuscript is the first of two companion manuscripts that introduce a computationally efficient distortion and stress prediction algorithm that is designed to drastically reduce compute time when integrated in to a process design optimization routine. In this first manuscript, we introduce a thermal circuit network (TCN) model to estimate the part temperature history during PBF, a major computational …


Effect Of Differences In The Primary Structure Of The A-Chain On The Aggregation Of Insulin Fragments, Paul P. Nakka, Ke Li, Daniel Forciniti Aug 2018

Effect Of Differences In The Primary Structure Of The A-Chain On The Aggregation Of Insulin Fragments, Paul P. Nakka, Ke Li, Daniel Forciniti

Chemical and Biochemical Engineering Faculty Research & Creative Works

Bovine and human insulin have similar primary structures. In this article, the region of the insulin A-chain of bovine and human insulin where the amino acid composition is different was studied. Bovine insulin fragment (BIF) and human insulin fragment (HIF) were synthesized in solid-phase peptide synthesis. The effects of pH, temperature, urea, ionic strength, and stirring on the formation of fibrils were studied using a fractional factorial resolution III experimental design. Fibrillation was monitored by fluorescence and infrared spectroscopy and optical microscopy. Both fragments formed fibrils at pH 1.6 and a temperature of 60 °C. The lag time and apparent …


Command Governor-Based Adaptive Control For Dynamical Systems With Matched And Unmatched Uncertainties, Metehan Yayla, Ehsan Arabi, Ali Turker Kutay, Tansel Yucelen Aug 2018

Command Governor-Based Adaptive Control For Dynamical Systems With Matched And Unmatched Uncertainties, Metehan Yayla, Ehsan Arabi, Ali Turker Kutay, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we propose a command governor-based adaptive control architecture for stabilizing uncertain dynamical systems with not only matched but also unmatched uncertainties and achieving the desired command following performance of a user-defined subset of the accessible states. In our proposed solution, online least-squares solutions for the matched and unmatched parameters are obtained through integration method and they are employed in the adaptive control framework. Specifically, the matched uncertainty is identified and its effect upon the system behavior is entirely attenuated. Moreover, using the unmatched uncertainty approximation obtained through radial basis function neural networks, the command governor signal is …