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Articles 1531 - 1560 of 2631

Full-Text Articles in Engineering

Open Source 3-D Printed Nutating Mixer, Dhwani K. Trivedi, Joshua M. Pearce Sep 2017

Open Source 3-D Printed Nutating Mixer, Dhwani K. Trivedi, Joshua M. Pearce

Department of Materials Science and Engineering Publications

As the open source development of additive manufacturing has led to low-cost desktop three-dimensional (3-D) printing, a number of scientists throughout the world have begun to share digital designs of free and open source scientific hardware. Open source scientific hardware enables custom experimentation, laboratory control, rapid upgrading, transparent maintenance, and lower costs in general. To aid in this trend, this study describes the development, design, assembly, and operation of a 3-D printable open source desktop nutating mixer, which provides a fixed 20° platform tilt angle for a gentle three-dimensional (gyrating) agitation of chemical or biological samples (e.g., DNA or blood …


Atmospheric Processes Affecting The Separation Of Volcanic Ash And So < Inf> 2 In Volcanic Eruptions: Inferences From The May 2011 Grímsvötn Eruption, Fred Prata, Mark Woodhouse, Herbert E. Huppert, Andrew Prata, Thor Thordarson, S. Carn Sep 2017

Atmospheric Processes Affecting The Separation Of Volcanic Ash And So < Inf> 2 In Volcanic Eruptions: Inferences From The May 2011 Grímsvötn Eruption, Fred Prata, Mark Woodhouse, Herbert E. Huppert, Andrew Prata, Thor Thordarson, S. Carn

Michigan Tech Publications, Part 1

The separation of volcanic ash and sulfur dioxide (SO2) gas is sometimes observed during volcanic eruptions. The exact conditions under which separation occurs are not fully understood but the phenomenon is of importance because of the effects volcanic emissions have on aviation, on the environment, and on the earth's radiation balance. The eruption of Grímsvötn, a subglacial volcano under the Vatnajökull glacier in Iceland during 21-28 May 2011 produced one of the most spectacular examples of ash and SO2 separation, which led to errors in the forecasting of ash in the atmosphere over northern Europe. Satellite data from several sources …


Cross-Correlation-Based Structural System Identification Using Unmanned Aerial Vehicles., Hyungchul Yoon, Vedhus Hoskere, Jong-Woong Park, Billie F. Spencer Sep 2017

Cross-Correlation-Based Structural System Identification Using Unmanned Aerial Vehicles., Hyungchul Yoon, Vedhus Hoskere, Jong-Woong Park, Billie F. Spencer

Michigan Tech Publications, Part 1

Computer vision techniques have been employed to characterize dynamic properties of structures, as well as to capture structural motion for system identification purposes. All of these methods leverage image-processing techniques using a stationary camera. This requirement makes finding an effective location for camera installation difficult, because civil infrastructure (i.e., bridges, buildings, etc.) are often difficult to access, being constructed over rivers, roads, or other obstacles. This paper seeks to use video from Unmanned Aerial Vehicles (UAVs) to address this problem. As opposed to the traditional way of using stationary cameras, the use of UAVs brings the issue of the camera …


Reference Data Set Of Volcanic Ash Physicochemical And Optical Properties, A. Vogel, S. Diplas, A. J. Durant, A. S. Azar, M. F. Sunding, William I. Rose, A. Sytchkova, C. Bonadonna, K. Krüger, A. Stohl Sep 2017

Reference Data Set Of Volcanic Ash Physicochemical And Optical Properties, A. Vogel, S. Diplas, A. J. Durant, A. S. Azar, M. F. Sunding, William I. Rose, A. Sytchkova, C. Bonadonna, K. Krüger, A. Stohl

Department of Geological and Mining Engineering and Sciences Publications

Uncertainty in the physicochemical and optical properties of volcanic ash particles creates errors in the detection and modeling of volcanic ash clouds and in quantification of their potential impacts. In this study, we provide a data set that describes the physicochemical and optical properties of a representative selection of volcanic ash samples from nine different volcanic eruptions covering a wide range of silica contents (50–80 wt % SiO2). We measured and calculated parameters describing the physical (size distribution, complex shape, and dense-rock equivalent mass density), chemical (bulk and surface composition), and optical (complex refractive index from ultraviolet to …


A Novel Applications Of Photogrammetry For Retaining Wall Assessment, Renee Oats, Rudiger Escobar-Wolf, Thomas Oommen Aug 2017

A Novel Applications Of Photogrammetry For Retaining Wall Assessment, Renee Oats, Rudiger Escobar-Wolf, Thomas Oommen

Michigan Tech Publications, Part 1

Retaining walls are critical geotechnical assets and their performance needs to be monitored in accordance to transportation asset management principles. Current practices for retaining wall monitoring consist mostly of qualitative approaches that provide limited engineering information or the methods include traditional geodetic surveying, which may provide high accuracy and reliability, but is costly and time-consuming. This study focuses on evaluating failure modes of a 2.43 m × 2.43 m retaining wall model using three-dimensional (3D) photogrammetry as a cost-effective quantitative alternative for retaining wall monitoring. As a remote sensing technique, photogrammetry integrates images collected from a camera and creates a …


Open Source 3d Printers: An Appropriate Technology For Building Low Cost Optics Labs For The Developing Communities, Jephias Gwamuri, Joshua M. Pearce Aug 2017

Open Source 3d Printers: An Appropriate Technology For Building Low Cost Optics Labs For The Developing Communities, Jephias Gwamuri, Joshua M. Pearce

Department of Materials Science and Engineering Publications

The recent introduction of RepRap (self-replicating rapid prototyper) 3-D printers and the resultant open source technological improvements have resulted in affordable 3-D printing, enabling low-cost distributed manufacturing for individuals. This development and others such as the rise of open source-appropriate technology (OSAT) and solar powered 3-D printing are moving 3-D printing from an industry based technology to one that could be used in the developing world for sustainable development. In this paper, we explore some specific technological improvements and how distributed manufacturing with open-source 3-D printing can be used to provide open-source 3-D printable optics components for developing world communities …


Distributed Control System For Parallel-Connected Dc Boost Converters, Steven Goldsmith Aug 2017

Distributed Control System For Parallel-Connected Dc Boost Converters, Steven Goldsmith

Michigan Tech Patents

The disclosed invention is a distributed control system for operating a DC bus fed by disparate DC power sources that service a known or unknown load. The voltage sources vary in v-i characteristics and have time-varying, maximum supply capacities. Each source is connected to the bus via a boost converter, which may have different dynamic characteristics and power transfer capacities, but are controlled through PWM. The invention tracks the time-varying power sources and apportions their power contribution while maintaining the DC bus voltage within the specifications. A central digital controller solves the steady-state system for the optimal duty cycle settings …


General Design Procedures For Airport-Based Solar Photovoltaic Systems, Anurag Anurag, Jiemin Zhang, Jephias Gwamuri, Joshua M. Pearce Aug 2017

General Design Procedures For Airport-Based Solar Photovoltaic Systems, Anurag Anurag, Jiemin Zhang, Jephias Gwamuri, Joshua M. Pearce

Department of Materials Science and Engineering Publications

A source of large surface areas for solar photovoltaic (PV) farms that has been largely overlooked in the 13,000 United States of America (U.S.) airports. This paper hopes to enable PV deployments in most airports by providing an approach to overcome the three primary challenges identified by the Federal Aviation Administration (FAA): (1) reflectivity and glare; (2) radar interference; and (3) physical penetration of airspace. First, these challenges and precautions that must be adhered to for safe PV projects deployment at airports are reviewed and summarized. Since one of the core concerns for PV and airport symbiosis is solar panel …


Effect Of Label Noise On The Machine-Learned Classification Of Earthquake Damage, Jared Frank, Umaa Rebbapragada, James Bialas, Thomas Oommen, Timothy C. Havens Aug 2017

Effect Of Label Noise On The Machine-Learned Classification Of Earthquake Damage, Jared Frank, Umaa Rebbapragada, James Bialas, Thomas Oommen, Timothy C. Havens

Michigan Tech Publications, Part 1

Automated classification of earthquake damage in remotely-sensed imagery using machine learning techniques depends on training data, or data examples that are labeled correctly by a human expert as containing damage or not. Mislabeled training data are a major source of classifier error due to the use of imprecise digital labeling tools and crowdsourced volunteers who are not adequately trained on or invested in the task. The spatial nature of remote sensing classification leads to the consistent mislabeling of classes that occur in close proximity to rubble, which is a major byproduct of earthquake damage in urban areas. In this study, …


Expanding Understanding Of Optical Variability In Lake Superior With A 4-Year Dataset, Colleen B. Mouw, Audrey B. Ciochetto, Brice Grunert, Angela W. Yu Jul 2017

Expanding Understanding Of Optical Variability In Lake Superior With A 4-Year Dataset, Colleen B. Mouw, Audrey B. Ciochetto, Brice Grunert, Angela W. Yu

Michigan Tech Publications, Part 1

Lake Superior is one of the largest freshwater lakes on our planet, but few optical observations have been made to allow for the development and validation of visible spectral satellite remote sensing products. The dataset described here focuses on coincidently observing inherent and apparent optical properties along with biogeochemical parameters. Specifically, we observe remote sensing reflectance, absorption, scattering, backscattering, attenuation, chlorophyll concentration, and suspended particulate matter over the ice-free months of 2013-2016. The dataset substantially increases the optical knowledge of the lake. In addition to visible spectral satellite algorithm development, the dataset is valuable for characterizing the variable light field, …


Impact Of Diy Home Manufacturing With 3d Printing On The Toy And Game Market, Emily Peterson, Joshua M. Pearce Jul 2017

Impact Of Diy Home Manufacturing With 3d Printing On The Toy And Game Market, Emily Peterson, Joshua M. Pearce

Department of Materials Science and Engineering Publications

The 2020 toy and game market is projected to be US$135 billion. To determine if 3D printing could affect these markets if consumers offset purchases by 3D printing free designs, this study investigates the 100 most popular downloaded designs at MyMiniFactory in a month. Savings are quantified for using a Lulzbot Mini 3D printer and three filament types: commercial filament, pellet-extruded filament, and post-consumer waste converted to filament with a recyclebot. Case studies probed the quality of: (1) six common complex toys; (2) Lego blocks; and (3) the customizability of open source board games. All filaments analyzed saved the user …


Fabricating Ordered 2-D Nano-Structured Arrays Using Nanosphere Lithography, Chenlong Zhang, Sandra Cvetanovic, Joshua M. Pearce Jul 2017

Fabricating Ordered 2-D Nano-Structured Arrays Using Nanosphere Lithography, Chenlong Zhang, Sandra Cvetanovic, Joshua M. Pearce

Department of Materials Science and Engineering Publications

Recent advances in the use of plasmonic metamaterials to improve absorption of light in thin-film solar photovoltaic devices has created a demand for a scalable method of patterning large areas with metal nanostructures deposited in an ordered array. This article describes two methods of fabricating ordered 2D nanosphere colloidal films: spin coating and interface coating. The two methods are compared and parameter optimization discussed. The study reveals that:

• For smaller nanosphere sizes, spin coating is more favorable, while for larger nanospheres, the angled interface coating provides more coverage and uniformity.

• A surfactant-free approach for interface coating is developed …


Identification Of Developmental Stage And Anatomical Fraction Contributions To Cell Wall Recalcitrance In Switchgrass, Jacob D. Crowe, Nicholas Feringa, Sivakumar Pattathil, Brian Merritt, Cliff Foster, Dayna Dines, Rebecca Ong, David B. Hodge Jul 2017

Identification Of Developmental Stage And Anatomical Fraction Contributions To Cell Wall Recalcitrance In Switchgrass, Jacob D. Crowe, Nicholas Feringa, Sivakumar Pattathil, Brian Merritt, Cliff Foster, Dayna Dines, Rebecca Ong, David B. Hodge

Department of Chemical Engineering Publications

Background

Heterogeneity within herbaceous biomass can present important challenges for processing feedstocks to cellulosic biofuels. Alterations to cell wall composition and organization during plant growth represent major contributions to heterogeneity within a single species or cultivar. To address this challenge, the focus of this study was to characterize the relationship between composition and properties of the plant cell wall and cell wall response to deconstruction by NaOH pretreatment and enzymatic hydrolysis for anatomical fractions (stem internodes, leaf sheaths, and leaf blades) within switchgrass at various tissue maturities as assessed by differing internode.

Results

Substantial differences in both cell wall composition …


Novel Durable Antimicrobial Ceramic With Embedded Copper Sub-Microparticles For A Steady-State Release Of Copper Ions, Adam J. Drelich, Jessie Miller, Robert Donofrio, Jaroslaw Drelich Jul 2017

Novel Durable Antimicrobial Ceramic With Embedded Copper Sub-Microparticles For A Steady-State Release Of Copper Ions, Adam J. Drelich, Jessie Miller, Robert Donofrio, Jaroslaw Drelich

Michigan Tech Publications, Part 1

Using pottery clay, porous ceramic stones were molded and then decorated with copper sub-microparticles inside the pores. Copper added antimicrobial functionality to the clay-based ceramic and showed ability in disinfecting water. Populations of both Staphylococcus aureus and Klebsiella pneumoniae in contaminated water were reduced by >99.9% in 3 h when exposed to an antimicrobial stone. This antimicrobial performance is attributed to a slow release of copper into water at both room and elevated temperatures. Copper is leached by water to produce ion concentrations in water at a level of 0.05–0.20 ppm after 24 to 72 h immersion tests. This concentration …


Harmonic Distortion Minimization In Power Grids With Wind And Electric Vehicles, Ritam Misra, Sumit Paudyal, Oguzhan Ceylan, Paras Mandal Jul 2017

Harmonic Distortion Minimization In Power Grids With Wind And Electric Vehicles, Ritam Misra, Sumit Paudyal, Oguzhan Ceylan, Paras Mandal

Michigan Tech Publications, Part 1

Power-electronic interfacing based devices such as wind generators (WGs) and electrical vehicles (EVs) cause harmonic distortions on the power grid. Higher penetration and uncoordinated operation of WGs and EVs can lead to voltage and current harmonic distortions, which may exceed IEEE limits. It is interesting to note that WGs and EVs have some common harmonic profiles. Therefore, when EVs are connected to the grid, the harmonic pollution EVs impart onto the grid can be reduced to some extent by the amount of wind power injecting into the grid and vice versa. In this context, this work studies the impact of …


Three Hundred And Sixty Degree Real-Time Monitoring Of 3-D Printing Using Computer Analysis Of Two Camera Views, Siranee Nuchitprasitchai, Michael C. Roggemann, Joshua M. Pearce Jul 2017

Three Hundred And Sixty Degree Real-Time Monitoring Of 3-D Printing Using Computer Analysis Of Two Camera Views, Siranee Nuchitprasitchai, Michael C. Roggemann, Joshua M. Pearce

Department of Materials Science and Engineering Publications

Prosumer (producing consumer)-based desktop additive manufacturing has been enabled by the recent radical reduction in 3-D printer capital costs created by the open-source release of the self-replicating rapid prototype (RepRap). To continue this success, there have been some efforts to improve reliability, which are either too expensive or lacked automation. A promising method to improve reliability is to use computer vision, although the success rates are still too low for widespread use. To overcome these challenges an open source low-cost reliable real-time optimal monitoring platform for 3-D printing from double cameras is presented here. This error detection system is implemented …


Free And Open Source 3-D Model Customizer For Websites To Democratize Design With Openscad, Yuenyong Nilsiam, Joshua M. Pearce Jul 2017

Free And Open Source 3-D Model Customizer For Websites To Democratize Design With Openscad, Yuenyong Nilsiam, Joshua M. Pearce

Department of Materials Science and Engineering Publications

3-D printing has entered the consumer market because of recent radical price declines. Consumers can save substantial money by offsetting purchases with DIY pre-designed 3-D printed products. However, even more value can be obtained with distributed manufacturing using mass customization. Unfortunately, the average consumer is not technically sophisticated enough to easily design their own products. One solution to this is the use of an overlay on OpenSCAD parametric code, although current solutions force users to relinquish all rights to their own designs. There is thus a substantial need in the open source design community for a libre 3-D model customizer, …


Spatial Variability Of Co < Inf> 2 Uptake In Polygonal Tundra: Assessing Low-Frequency Disturbances In Eddy Covariance Flux Estimates, Norbert Pirk, Jakob Sievers, Jordan Mertes, Frans Jan W. Parmentier, Mikhail Mastepanov, Torben R. Christensen Jun 2017

Spatial Variability Of Co < Inf> 2 Uptake In Polygonal Tundra: Assessing Low-Frequency Disturbances In Eddy Covariance Flux Estimates, Norbert Pirk, Jakob Sievers, Jordan Mertes, Frans Jan W. Parmentier, Mikhail Mastepanov, Torben R. Christensen

Michigan Tech Publications, Part 1

The large spatial variability in Arctic tundra complicates the representative assessment of CO2 budgets. Accurate measurements of these heterogeneous landscapes are, however, essential to understanding their vulnerability to climate change. We surveyed a polygonal tundra lowland on Svalbard with an unmanned aerial vehicle (UAV) that mapped ice-wedge morphology to complement eddy covariance (EC) flux measurements of CO2. The analysis of spectral distributions showed that conventional EC methods do not accurately capture the turbulent CO2 exchange with a spatially heterogeneous surface that typically features small flux magnitudes. Nonlocal (low-frequency) flux contributions were especially pronounced during snowmelt and introduced a large bias …


Effects Of Short Term Hypoxia-Preconditioning On Glial Phenotype Induction Of Human Mesenchymal Stem Cells, Zichen Qian, Qi Xing, Corey Fase, Kyle Jansen, Feng Zhao Jun 2017

Effects Of Short Term Hypoxia-Preconditioning On Glial Phenotype Induction Of Human Mesenchymal Stem Cells, Zichen Qian, Qi Xing, Corey Fase, Kyle Jansen, Feng Zhao

Michigan Tech Publications, Part 1

Development of successful clinical treatments for peripheral nerve injury is limited due to the complications behind neural physiology. Human mesenchymal stem cells (hMSCs) have the ability to directly promote tissue repair and protect cells at the injury site. Studies have shown that hMSCs can be transplanted to improve nerve regeneration. Hypoxic culture condition has been proven to maintain the stemness of hMSCs for later differentiation. In this study, we investigated the effects of low oxygen (O2) (2% and 5% O2) pre-treatment and initial seeding density (500, 1000, and 2000 cells/cm2) on glial protein expression …


Energy Payback Time Of A Solar Photovoltaic Powered Waste Plastic Recyclebot System, Shan Zhong, Pratiksha Rakhe, Joshua M. Pearce Jun 2017

Energy Payback Time Of A Solar Photovoltaic Powered Waste Plastic Recyclebot System, Shan Zhong, Pratiksha Rakhe, Joshua M. Pearce

Department of Materials Science and Engineering Publications

The growth of both plastic consumption and prosumer 3-D printing are driving an interest in producing 3-D printer filaments from waste plastic. This study quantifies the embodied energy of a vertical DC solar photovoltaic (PV) powered recyclebot based on life cycle energy analysis and compares it to horizontal AC recyclebots, conventional recycling, and the production of a virgin 3-D printer filament. The energy payback time (EPBT) is calculated using the embodied energy of the materials making up the recyclebot itself and is found to be about five days for the extrusion of a poly lactic acid (PLA) filament or 2.5 …


Open Source Multi-Head 3d Printer For Polymer-Metal Composite Component Manufacturing, J. Laureto, Joshua M. Pearce Jun 2017

Open Source Multi-Head 3d Printer For Polymer-Metal Composite Component Manufacturing, J. Laureto, Joshua M. Pearce

Department of Materials Science and Engineering Publications

As low-cost desktop 3D printing is now dominated by free and open source self-replicating rapid prototype (RepRap) derivatives, there is an intense interest in extending the scope of potential applications to manufacturing. This study describes a manufacturing technology that enables a constrained set of polymer-metal composite components. This paper provides (1) free and open source hardware and (2) software for printing systems that achieves metal wire embedment into a polymer matrix 3D-printed part via a novel weaving and wrapping method using (3) OpenSCAD and parametric coding for customized g-code commands. Composite parts are evaluated from the technical viability of manufacturing …


Me-Em Enewsbrief, June 2017, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University Jun 2017

Me-Em Enewsbrief, June 2017, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.


Off-Line Handwritten Signature Recognition By Wavelet Entropy And Neural Network, Khaled Daqrouq, Husam Sweidan, Ahmad Balamesh, Mohammed N. Ajour May 2017

Off-Line Handwritten Signature Recognition By Wavelet Entropy And Neural Network, Khaled Daqrouq, Husam Sweidan, Ahmad Balamesh, Mohammed N. Ajour

Michigan Tech Publications, Part 1

Handwritten signatures are widely utilized as a form of personal recognition. However, they have the unfortunate shortcoming of being easily abused by those who would fake the identification or intent of an individual which might be very harmful. Therefore, the need for an automatic signature recognition system is crucial. In this paper, a signature recognition approach based on a probabilistic neural network (PNN) and wavelet transform average framing entropy (AFE) is proposed. The system was tested with a wavelet packet (WP) entropy denoted as a WP entropy neural network system (WPENN) and with a discrete wavelet transform (DWT) entropy denoted …


Analysis Of Preparation And Properties On Shape Memory Hydrogenated Epoxy Resin Used For Asphalt Mixtures, Biao Ma, Xueyan Zhou, Kun Wei, Yanzhen Bo, Zhanping You May 2017

Analysis Of Preparation And Properties On Shape Memory Hydrogenated Epoxy Resin Used For Asphalt Mixtures, Biao Ma, Xueyan Zhou, Kun Wei, Yanzhen Bo, Zhanping You

Michigan Tech Publications, Part 1

The objective of this investigation is to prepare the shape memory hydrogenated epoxy resin used for asphalt mixtures (SM-HEP-AM) and study its properties. The shape memory hydrogenated epoxy resin (SM-HEP) is prepared using hydrogenated bisphenol A epoxy resin (AL-3040), polypropylene glycol diglycidylether diacrylate (JH-230), and isophorone diamine (IPDA). The formulations of the SM-HEP-AM are obtained by the linearly fitted method. The thermo-mechanical property, molecular structure, and shape-memory performance of the SM-HEP-AM are studied. The glass-transition temperature (Tg) is determined using the differential scanning calorimeter (DSC). The results proved that the Tg level increased when the JH-230 content …


3-D Printing Open-Source Click-Muac Bands For Identification Of Malnutrition, Ross Michaels, Joshua M. Pearce May 2017

3-D Printing Open-Source Click-Muac Bands For Identification Of Malnutrition, Ross Michaels, Joshua M. Pearce

Department of Materials Science and Engineering Publications

No abstract provided.


Gradient-Enriched Finite Element Methodology For Axisymmetric Problems, C. Bagni, H. Askes, E. C. Aifantis Apr 2017

Gradient-Enriched Finite Element Methodology For Axisymmetric Problems, C. Bagni, H. Askes, E. C. Aifantis

Michigan Tech Publications, Part 1

Due to the axisymmetric nature of many engineering problems, bi-dimensional axisymmetric finite elements play an important role in the numerical analysis of structures, as well as advanced technology micro/nano-components and devices (nano-tubes, nano-wires, micro-/nano-pillars, micro-electrodes). In this paper, a straightforward C0-continuous gradient-enriched finite element methodology is proposed for the solution of axisymmetric geometries, including both axisymmetric and non-axisymmetric loads. Considerations about the best integration rules and an exhaustive convergence study are also provided along with guidances on optimal element size. Moreover, by applying the present methodology to cylindrical bars characterised by a circumferential sharp crack, the ability of the present …


Emerging Business Models For Open Source Hardware, Joshua M. Pearce Mar 2017

Emerging Business Models For Open Source Hardware, Joshua M. Pearce

Department of Materials Science and Engineering Publications

The rise of Free and Open Source models for software development has catalyzed the growth of Free and Open Source hardware (also known as “Libre Hardware”). Libre Hardware is gaining significant traction in the scientific hardware community, where there is evidence that open development creates both technically superior and far less expensive scientific equipment than proprietary models. In this article, the evidence is reviewed and a collection of examples of business models is developed to service scientists who have the option to manufacture their own equipment using Open Source designs. Profitable Libre Hardware business models are reviewed, which includes kit, …


Ultrasonic Techniques For Air Void Size Distribution And Property Evaluation In Both Early-Age And Hardened Concrete Samples, Shuaicheng Guo, Qingli Dai, Xiao Sun, Ye Sun, Zhen Liu Mar 2017

Ultrasonic Techniques For Air Void Size Distribution And Property Evaluation In Both Early-Age And Hardened Concrete Samples, Shuaicheng Guo, Qingli Dai, Xiao Sun, Ye Sun, Zhen Liu

Department of Civil, Environmental, and Geospatial Engineering Publications

Entrained air voids can improve the freeze-thaw durability of concrete, and also affect its mechanical and transport properties. Therefore, it is important to measure the air void structure and understand its influence on concrete performance for quality control. This paper aims to measure air void structure evolution at both early-age and hardened stages with the ultrasonic technique, and evaluates its influence on concrete properties. Three samples with different air entrainment agent content were specially prepared. The air void structure was determined with optimized inverse analysis by achieving the minimum error between experimental and theoretical attenuation. The early-age sample measurement showed …


An Improved Electron Pre-Sheath Model For Tss-1r Current Enhancement Computations, Chunpei Cai Mar 2017

An Improved Electron Pre-Sheath Model For Tss-1r Current Enhancement Computations, Chunpei Cai

Michigan Tech Publications, Part 1

This report presents improvements of investigations on the Tethered Satellite System (TSS)-1R electron current enhancement due to magnetic limited collections. New analytical expressions are obtained for the potential and temperature changes across the pre-sheath. The mathematical treatments in this work are more rigorous than one past approach. More experimental measurements collected in the ionosphere during the TSS-1R mission are adopted for validations. The relations developed in this work offer two bounding curves for these data points quite successfully; the average of these two curves is close to the curve-fitting results for the measurements; and an average of 2.95 times larger …


Biomechanics And Imaging, Jingfeng Jiang Mar 2017

Biomechanics And Imaging, Jingfeng Jiang

TechTalks

From the perspective of biomechanics, my research is multidisciplinary, bridging the gap between physiology/biology and quantitative sciences. Currently, the applications are on cancer detection and differentiation, therapeutic monitoring, staging liver fibrosis, risk assessment of aneurysm rupture, and more.