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2019

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Articles 9121 - 9150 of 10505

Full-Text Articles in Engineering

Resonant Acoustic Wave Assisted Spin-Transfer-Torque Switching Of Nanomagnets, Austin R. Roe Jan 2019

Resonant Acoustic Wave Assisted Spin-Transfer-Torque Switching Of Nanomagnets, Austin R. Roe

Theses and Dissertations

We studied the possibility of achieving an order of magnitude reduction in the energy dissipation needed to write bits in perpendicular magnetic tunnel junctions (p-MTJs) by simulating the magnetization dynamics under a combination of resonant surface acoustic waves (r-SAW) and spin-transfer-torque (STT). The magnetization dynamics were simulated using the Landau-Lifshitz-Gilbert equation under macrospin assumption with the inclusion of thermal noise. We studied such r-SAW assisted STT switching of nanomagnets for both in-plane elliptical and circular perpendicular magnetic anisotropy (PMA) nanomagnets and show that while thermal noise affects switching probability in in-plane nanomagnets, the PMA nanomagnets are relatively robust to the …

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The Next-Generation Retail Electricity Market In The Context Of Distributed Energy Resources: Vision And Integrating Framework, Josue Campos Do Prado, Wei Qiao, Liyan Qu, Julio Romero Aguero Jan 2019

The Next-Generation Retail Electricity Market In The Context Of Distributed Energy Resources: Vision And Integrating Framework, Josue Campos Do Prado, Wei Qiao, Liyan Qu, Julio Romero Aguero

Department of Electrical and Computer Engineering: Faculty Publications

The increasing adoption of distributed energy resources (DERs) and smart grid technologies (SGTs) by end-user retail customers is changing significantly both technical and economic operations in the distribution grid. The next-generation retail electricity market will promote decentralization, efficiency, and competitiveness by accommodating existing and new agents through new business models and transactive approaches in an advanced metering infrastructure (AMI). However, these changes will bring several technical challenges to be addressed in transmission and distribution systems. Considerable activities have been carried out worldwide to study the impacts of integrating DERs into the grid and in the wholesale electricity market. However, the …

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The Temporal-Spatial Evolution Of Electron Dynamics Induced By Femtosecond Double Pulses, Changji Pan, Lan Jiang, Jingya Sun, Qingsong Wang, Feifei Wang, Yongfeng Lu Jan 2019

The Temporal-Spatial Evolution Of Electron Dynamics Induced By Femtosecond Double Pulses, Changji Pan, Lan Jiang, Jingya Sun, Qingsong Wang, Feifei Wang, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

The temporal and spatial electron dynamics were investigated under irradiation of temporally shaped femtosecond double pulses. Filament split was observed upon arrival of the second pulse, which was attributed to the emergence of transient high-reflective surface induced by the first pulse. The electron density analysis showed that the total deposition energy of double pulses case was generally higher than that of single pulse case. Particularly, the maximum deposition energy was obtained at 350 fs separation time of double pulses. The results of our experiment demonstrated optimization of energy deposition efficiency by temporally shaping laser pulses, which will benefit the fabrication …

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Neutrophil Activation In Systemic Capillary Leak Syndrome (Clarkson Disease), Zhihui Xie, Douglas B. Kuhns, Xuesong Gu, Hasan H. Otu, Towia A. Libermann, John I. Gallin, Samir M. Parikh, Kirk M. Druey Jan 2019

Neutrophil Activation In Systemic Capillary Leak Syndrome (Clarkson Disease), Zhihui Xie, Douglas B. Kuhns, Xuesong Gu, Hasan H. Otu, Towia A. Libermann, John I. Gallin, Samir M. Parikh, Kirk M. Druey

Department of Electrical and Computer Engineering: Faculty Publications

Systemic capillary leak syndrome (SCLS; Clarkson disease) is a rare orphan disorder characterized by transient yet recurrent episodes of hypotension and peripheral oedema due to diffuse vascular leakage of fluids and proteins into soft tissues. Humoral mediators, cellular responses and genetic features accounting for the clinical phenotype of SCLS are virtually unknown. Here, we searched for factors altered in acute SCLS plasma relative to matched convalescent samples using multiplexed aptamer‐based proteomic screening. Relative amounts of 612 proteins were changed greater than twofold and 81 proteins were changed at least threefold. Among the most enriched proteins in acute SCLS plasma were …

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Direct Observation Of Structure-Assisted Filament Splitting During Ultrafast Multiplepulse Laser Ablation, Feifei Wang, Changji Pan, Jingya Sun, Qingsong Wang, Yongfeng Lu, Lan Jiang Jan 2019

Direct Observation Of Structure-Assisted Filament Splitting During Ultrafast Multiplepulse Laser Ablation, Feifei Wang, Changji Pan, Jingya Sun, Qingsong Wang, Yongfeng Lu, Lan Jiang

Department of Electrical and Computer Engineering: Faculty Publications

Laser-induced plasma evolution in fused silica through multipulse laser ablation was studied using pump-probe technology. Filament splitting was observed in the early stage of plasma evolution (before ~300 fs). This phenomenon can be attributed to competition between laser divergent propagation induced by a pre-pulse-induced crater and the nonlinear self-focusing effect. This effect was validated through simulation results. With the increasing pulse number, the appearance of filament peak electron density was postponed. Furthermore, a second peak in the filament and peak position separation were observed because of an optical path difference between the lasers propagating from the crater center and edge. …

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Monitoring Aging Of Power Semiconductor Devices Based On Case Temperature, Wei Qiao, Ze Wang, Liyan Qu Jan 2019

Monitoring Aging Of Power Semiconductor Devices Based On Case Temperature, Wei Qiao, Ze Wang, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

The aging of an electronic component in an electronic power converter can be monitored based on two or more case temperature measurements. A power electronic device is enclosed in a package having a baseplate, in which the power electronic device generates heat during operation and the baseplate transfers heat to a heat dissipating device or a cooling device. Sensors measure temperatures at first and second locations on a surface of the baseplate. A data processor calculates a value for a first parameter based on the temperatures at the first and second locations, in which the first parameter is indicative of …

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Multi-Pig Part Detection And Association With A Fully-Convolutional Network, Eric T. Psota, Mateusz Mittek, Lance C. Pérez, Ty Schmidt, Benny Mote Jan 2019

Multi-Pig Part Detection And Association With A Fully-Convolutional Network, Eric T. Psota, Mateusz Mittek, Lance C. Pérez, Ty Schmidt, Benny Mote

Department of Electrical and Computer Engineering: Faculty Publications

Computer vision systems have the potential to provide automated, non-invasive monitoring of livestock animals, however, the lack of public datasets with well-defined targets and evaluation metrics presents a significant challenge for researchers. Consequently, existing solutions often focus on achieving task-specific objectives using relatively small, private datasets. This work introduces a new dataset and method for instance-level detection of multiple pigs in group-housed environments. The method uses a single fully-convolutional neural network to detect the location and orientation of each animal, where both body part locations and pairwise associations are represented in the image space. Accompanying this method is a new …

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Beam Manipulation Mechanisms Of Dielectric Metasurfaces, Baoshan Guo, Lan Jiang, Yanhong Hua, Ningwei Zhan, Jingang Jia, Kunpeng Chu, Yongfeng Lu Jan 2019

Beam Manipulation Mechanisms Of Dielectric Metasurfaces, Baoshan Guo, Lan Jiang, Yanhong Hua, Ningwei Zhan, Jingang Jia, Kunpeng Chu, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Dielectric metasurfaces can achieve flexible beam manipulations. Herein, we study dielectric metasurfaces with different refractive indices, periods, incident angles, and cross-sectional shapes to determine the metasurface working mechanisms. Perfect transmission mainly depends on multipolar interference that can be used to control the transmission modes through the hybrid periods, hybrid cross sections, and multilayers. Perfect reflection is strongly influenced by the period of the metasurface and occurs only when the period is shorter than incident wavelength, which can be attributed to the lattice coupling. Furthermore, lattice coupling can be classified into two types with distinct properties: vertical mode and horizontal mode …

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Foreword For The Inaugural Issue, Dongming Guo, Yongfeng Lu Jan 2019

Foreword For The Inaugural Issue, Dongming Guo, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

The International Journal of Extreme Manufacturing is a leading, worldwide scientific journal focused on the fields of extreme manufacturing. Published within it are the latest scientific and engineering achievements in related fields, as well as pioneering scientific, technological, and engineering innovations and developments.

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Zebrafish Macroh2a Variants Have Distinct Embryo Localization And Function, E. Gonzalez-Munoz, Y. Arboleda-Estudillo, S. K. Chanumolu, H. H. Otu, J. B. Cibelli Jan 2019

Zebrafish Macroh2a Variants Have Distinct Embryo Localization And Function, E. Gonzalez-Munoz, Y. Arboleda-Estudillo, S. K. Chanumolu, H. H. Otu, J. B. Cibelli

Department of Electrical and Computer Engineering: Faculty Publications

Mouse and cell-based studies have shown that macroH2A histone variants predominantly associate with heterochromatin. Functional studies found that macroH2As are involved in gene repression, inhibiting the acquisition of pluripotency and preserving cell differentiation. However, only a few studies have analysed the role of macroH2A during early embryo development. We report the development of transgenic zebrafish lines expressing macroH2A isoforms (mH2A1 and mH2A2) fusion proteins (with GFP) under identified endogenous promoters. We found that mH2A1 and mH2A2 have different spatial and temporal expression patterns during embryonic development. mH2A1 is expressed mostly in the extraembryonic Yolk Syncytial Layer (YSL) starting before shield …

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Rechargeable Multi - Cell Battery, Wei Qiao, Taesic Kim, Liyan Qu Jan 2019

Rechargeable Multi - Cell Battery, Wei Qiao, Taesic Kim, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

A method for power management of a multi-cell battery includes identifying a desired power value and voltage value, determining a battery voltage value and a battery current value for a battery, determining a number of battery banks from a plurality of battery banks to use for the battery, where each battery bank includes one or more battery cells (or battery modules), checking availability of each of the one or more battery cells (or battery modules), selecting one or more battery banks from the plurality of battery banks, where the selection of a battery bank is based on the availability of …

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Longitudinal Phonon Plasmon Mode Coupling In Β-Ga2O3, Mathias Schubert, Alyssa Mock, Rafal Korlacki, Sean Knight, Zbigniew Galazka, Günther Wagner, Virginia Wheeler, Marko Tadjer, Ken Goto, Vanya Darakchieva Jan 2019

Longitudinal Phonon Plasmon Mode Coupling In Β-Ga2O3, Mathias Schubert, Alyssa Mock, Rafal Korlacki, Sean Knight, Zbigniew Galazka, Günther Wagner, Virginia Wheeler, Marko Tadjer, Ken Goto, Vanya Darakchieva

Department of Electrical and Computer Engineering: Faculty Publications

In this letter, we investigate a set of n-type single crystals of monoclinic symmetry β-Ga2O3 with different free electron concentration values by generalized far infrared and infrared spectroscopic ellipsometry. In excellent agreement with our previous model prediction, we find here by experiment that longitudinal-phonon-plasmon coupled modes are polarized either within the monoclinic plane or perpendicular to the monoclinic plane. As predicted, all modes change the amplitude and frequency with the free electron concentration. The most important observation is that all longitudinal-phonon-plasmon coupled modes polarized within the monoclinic plane continuously change their direction as a function of …

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Extraction Of Astaxanthin From Engineered Camelina Sativa Seed Using Ethanol-Modified Supercritical Carbon Dioxide, Liyang Xie, Edgar B. Cahoon, Yue Zhang, Ozan Ciftci Jan 2019

Extraction Of Astaxanthin From Engineered Camelina Sativa Seed Using Ethanol-Modified Supercritical Carbon Dioxide, Liyang Xie, Edgar B. Cahoon, Yue Zhang, Ozan Ciftci

Department of Food Science and Technology: Faculty Publications

Natural astaxanthin, a high-value carotenoid that is currently extracted mainly from marine organisms, was extracted from engineered camelina seed using ethanol-modified supercritical carbon dioxide (SC-CO2) for the first time, and compared with hexane and accelerated solvent extraction using hexane and ethanol. Response surface methodology (RSM) based on central composite rotatable design was employed to investigate the effect of pressure (30–45 MPa), temperature (40–60 °C), and ethanol concentration (10–35%, w/w). RSM-optimized conditions (41.6 MPa, 36.6 °C and 42.0% ethanol concentration) predicted the astaxanthin concentration as 437 μg/g oil, whereas the actual concentration was 421 ± 14 μg/g oil. Astaxanthin …

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High Strength, Deformable Nanotwinned Al–Co Alloys, S. Xue, Qiang Li, D. Y. Xie, Y. F. Zhang, Han Wang, Haiyan Wong, J. Wang, Xinghang Zhang Jan 2019

High Strength, Deformable Nanotwinned Al–Co Alloys, S. Xue, Qiang Li, D. Y. Xie, Y. F. Zhang, Han Wang, Haiyan Wong, J. Wang, Xinghang Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

Aluminum (Al) alloys have been widely used in the transportation industry. However, most highstrength Al alloys to date have limited mechanical strength, on the order of a few hundred MPa, which is much lower than the flow stress of high-strength steels. In this study, we show the fabrication of nanocrystalline Al alloys with high-density growth twins enabled by a few atomic percent of Co solute. In situ uniaxial compression tests show that the flow stress of Al–Co solid solution alloys exceeds 1.5 GPa, while good work hardening capability is maintained. This study provides a new perspective on the design of …

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A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson Jan 2019

A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson

Department of Mechanical and Materials Engineering: Faculty Publications

The existing surgical robots for laparoscopic surgery offer no or limited force feedback, and there are many problems for the traditional sensor-based solutions. This paper builds a teleoperation surgical system and validates the effectiveness of sensorless force feedback. The tool-tissue interaction force at the surgical grasper tip is estimated using the driving motor’s current, and fed back to the master robot with a position-force bilateral control algorithm. The stiffness differentiation experiment and tumor detection experiment were conducted. In the stiffness differentiation experiment, 43 out of 45 pairs of ranking relationships were identified correctly, yielding a success rate of 96%. In …

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Effects Of Compositional Tailoring On Drug Delivery Behaviours Of Silica Xerogel/Polymer Core-Shell Composite Nanoparticles, Wenfei Huang, Chi Pong Tsui, Chak Yin Tang, Linxia Gu Jan 2019

Effects Of Compositional Tailoring On Drug Delivery Behaviours Of Silica Xerogel/Polymer Core-Shell Composite Nanoparticles, Wenfei Huang, Chi Pong Tsui, Chak Yin Tang, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Conventional core-shell polymer nanoparticles usually exhibit a rapid release rate with their release kinetics mainly adjusted through changing composition of the polymer shells, limiting their applications for prolonged drug delivery. As a solution to these problems, silica xerogel/polymer core-shellstructured composite nanoparticles have been proposed. Different with our previous work centring on studying process variables, we here focused on investigating the effects of key compositional variables on essential properties of the composite nanoparticles. The drug release profiles (in vitro) were well interpreted by the Baker and Lonsdale model on a predicted two-stage basis. The first stage (<1 day) was well controlled from 18.6% to 45.9%; the second stage (1–14 days) was tailored in a range from 28.7 to 58.2% by changing the composition of the silica xerogel cores and polymeric shells. A substantial achievement was reducing the release rate by more than 40 times compared with that of conventional polymer nanoparticles by virtue of the silica xerogel cores. A semi-empirical model was also established in the first attempt to describe the effects of polymer concentration and drug loading capacity on the size of the composite nanoparticles. All these results indicated that the composite nanoparticles are promising candidates for prolonged drug delivery applications.

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Unveiling The Operation Mechanism Of Layered Perovskite Solar Cells, Yun Lin, Yanjun Fang, Jingjing Zhao, Yuchuan Shao, Samuel J. Stuard, Masrur Morshed Nahid, Harald Ade, Qi Wang, Jeffrey E. Shield, Ninghao Zhou, Andrew M. Moran, Jinsong Huang Jan 2019

Unveiling The Operation Mechanism Of Layered Perovskite Solar Cells, Yun Lin, Yanjun Fang, Jingjing Zhao, Yuchuan Shao, Samuel J. Stuard, Masrur Morshed Nahid, Harald Ade, Qi Wang, Jeffrey E. Shield, Ninghao Zhou, Andrew M. Moran, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Layered perovskites have been shown to improve the stability of perovskite solar cells while its operation mechanism remains unclear. Here we investigate the process for the conversion of light to electrical current in high performance layered perovskite solar cells by examining its real morphology. The layered perovskite films in this study are found to be a mixture of layered and three dimensional (3D)-like phases with phase separations at micrometer and nanometer scale in both vertical and lateral directions. This phase separation is explained by the surface initiated crystallization process and the competition of the crystallization between 3D-like and layered perovskites. …

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Monolithic Heat-Transfer Device, Sidy Ndao, George Gogos, Dennis Alexander, Troy Anderson, Craig Zuhlke Jan 2019

Monolithic Heat-Transfer Device, Sidy Ndao, George Gogos, Dennis Alexander, Troy Anderson, Craig Zuhlke

Department of Mechanical and Materials Engineering: Faculty Publications

A monolithic heat-transfer device can include a container wall configured to retain a working fluid, where the container wall is formed of a single material. The container wall also includes an interior surface configured to be in fluid communication with the working fluid. The monolithic heat-transfer device also includes a channel disposed in the interior surface of the container wall, where the channel comprises a microstructure and a nanostructure. The microstructure and the nanostructure are materially contiguous with the single material forming the container wall. In some embodiments, the nanostructure comprises one or more layers of nanoparticles. The monolithic heat-transfer …

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Higher-Order Overtone Thickness-Shear Vibrations Of Multilayered Thin-Film Acoustic Wave Resonators And Angular Rate Sensing, Hui Chen, Ji Wang, Jianke Du, Jiashi Yang Jan 2019

Higher-Order Overtone Thickness-Shear Vibrations Of Multilayered Thin-Film Acoustic Wave Resonators And Angular Rate Sensing, Hui Chen, Ji Wang, Jianke Du, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We propose a new structure for piezoelectric gyroscopes. It is made from multilayered thin films of AlN or ZnO with alternating c-axes along the film thickness. It is shown theoretically that when such a film is electrically driven into higher-order overtone thickness-shear vibration in one of the two in-plane directions of the film and is rotating about the film normal, the Coriolis force due to the rotation causes a higher-order overtone thicknessshear vibration in a perpendicular direction with an electrical output that can be used to measure the angular rate of the rotation. Different from existing thickness-shear mode piezoelectric gyroscopes …

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3d Printing Of Hybrid Mos2-Graphene Aerogels As Highly Porous Electrode Materials For Sodium Ion Battery Anodes, Emery Brown, Pengli Yan, Halil Tekik, Ayyappan Elangovan, Jian Wang, Dong Lin, Jun Li Jan 2019

3d Printing Of Hybrid Mos2-Graphene Aerogels As Highly Porous Electrode Materials For Sodium Ion Battery Anodes, Emery Brown, Pengli Yan, Halil Tekik, Ayyappan Elangovan, Jian Wang, Dong Lin, Jun Li

Department of Mechanical and Materials Engineering: Faculty Publications

This study reports a 3D freeze-printing method that integrates inkjet printing and freeze casting to control both the microstructure and macroporosity via formation of ice microcrystals during printing. A viscous aqueous ink consisting of a molecular MoS2 precursor (ammonium thiomolybdate) mixed with graphene oxide (GO) nanosheets is used in the printing process. Post-treatments by freeze-drying and reductive thermal annealing convert the printed intermediate mixture into a hybrid structure consisting of MoS2 nanoparticles anchored on the surface of 2D rGO nanosheets in a macroporous framework, which is fully characterized with FESEM, TEM, XRD, Raman spectroscopy and TGA. The resulting …

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Three-Dimensional Character Of The Deformation Twin In Magnesium, Y. Liu, P.Z. Tang, M.Y. Gong, R.J. Mccabe, J. Wang, C.N. Tome Jan 2019

Three-Dimensional Character Of The Deformation Twin In Magnesium, Y. Liu, P.Z. Tang, M.Y. Gong, R.J. Mccabe, J. Wang, C.N. Tome

Department of Mechanical and Materials Engineering: Faculty Publications

Deformation twins are three-dimensional domains, traditionally viewed as ellipsoids because of their two-dimensional lenticular sections. In this work, we performed statistical analysis of twin shapes viewing along three orthogonal directions: the ‘dark side’ (DS) view along the twin shear direction (η1), the twinning plane normal (TPN) view (k1) and the ‘bright side’ (BS) view along the direction λ(=k1 × η1). Our electron back-scatter diffraction results show that twins in the DS and BS views normally exhibit a lenticular shape, whereas they show an irregular shape in the TPN view. Moreover, the findings in the TPN view revealed that twins grow …

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Spatiotemporal Characterizations Of Spontaneously Beating Cardiomyocytes With Adaptive Reference Digital Image Correlation, Akankshya Shradhanjali, Brandon D. Riehl, Bin Duan, Ruiguo Yang, Jung Yul Lim Jan 2019

Spatiotemporal Characterizations Of Spontaneously Beating Cardiomyocytes With Adaptive Reference Digital Image Correlation, Akankshya Shradhanjali, Brandon D. Riehl, Bin Duan, Ruiguo Yang, Jung Yul Lim

Department of Mechanical and Materials Engineering: Faculty Publications

We developed an Adaptive Reference-Digital Image Correlation (AR-DIC) method that enables unbiased and accurate mechanics measurements of moving biological tissue samples. We applied the AR-DIC analysis to a spontaneously beating cardiomyocyte (CM) tissue, and could provide correct quantifications of tissue displacement and strain for the beating CMs utilizing physiologically-relevant, sarcomere displacement length-based contraction criteria. The data were further synthesized into novel spatiotemporal parameters of CM contraction to account for the CM beating homogeneity, synchronicity, and propagation as holistic measures of functional myocardial tissue development. Our AR-DIC analyses may thus provide advanced non-invasive characterization tools for assessing the development of spontaneously …

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Insulating Tunneling Contact For Efficient And Stable Perovskite Solar Cells, Jinsong Huang, Xiaopeng Zheng, Qi Wang, Yang Bai, Qingfeng Dong Jan 2019

Insulating Tunneling Contact For Efficient And Stable Perovskite Solar Cells, Jinsong Huang, Xiaopeng Zheng, Qi Wang, Yang Bai, Qingfeng Dong

Department of Mechanical and Materials Engineering: Faculty Publications

Perovskite-based photoactive devices, such as solar cells, include an insulating tunneling layer inserted between the perovskite photoactive material and the electron collection layer to reduce charge recombination and concomitantly provide water resistant properties to the device.

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Beyond The Toolpath: Site-Specific Melt Pool Size Control Enables Printing Of Extra-Toolpath Geometry In Laser Wire-Based Directed Energy Deposition, Brian T. Gibson, Bradley S. Richardson, Tayler W. Undermann, Lonnie J. Love Jan 2019

Beyond The Toolpath: Site-Specific Melt Pool Size Control Enables Printing Of Extra-Toolpath Geometry In Laser Wire-Based Directed Energy Deposition, Brian T. Gibson, Bradley S. Richardson, Tayler W. Undermann, Lonnie J. Love

Department of Mechanical and Materials Engineering: Faculty Publications

A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser wire-based directed energy deposition is demonstrated with a novel modification, i.e., site-specific changes to the controller setpoint were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary three-dimensional (3D) printed component geometry. The present work shows that, through this technique, it is possible to print a specific …

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Disposable Fluidic Self-Propelling Robot For Traversing A Tubular Passage, Carl Nelson, Benjamin Terry, Abolfazl Pourghodrat, Hossein Dehghani, Dmitry Oleynikov, Prithviraj Dasgupta Jan 2019

Disposable Fluidic Self-Propelling Robot For Traversing A Tubular Passage, Carl Nelson, Benjamin Terry, Abolfazl Pourghodrat, Hossein Dehghani, Dmitry Oleynikov, Prithviraj Dasgupta

Department of Mechanical and Materials Engineering: Faculty Publications

A probe for traversing a tubular passage includes an introducer to be supported at an entrance to the tubular passage. The probe also includes a probe tip to traverse the tubular passage, and a tube with an inflatable tube segment. In some embodiments, the inflatable tube segment is storable in the probe tip. The inflatable tube segment is configured to be inflated to push the probe tip away from the introducer toward an end on the tubular passage. In some embodiments, the probe includes a sealing mechanism, whre the sealing mechanism can be positioned between the inflatable tube segment of …

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Mechanical Stresses Associated With Flattening Of Human Femoropopliteal Artery Specimens During Planar Biaxial Testing And Their Effects On The Calculated Physiologic Stress-Stretch State, Majid Jadidi, Anastasia Desyatova, Jason N. Mactaggart, Alexey Kamenskiy Jan 2019

Mechanical Stresses Associated With Flattening Of Human Femoropopliteal Artery Specimens During Planar Biaxial Testing And Their Effects On The Calculated Physiologic Stress-Stretch State, Majid Jadidi, Anastasia Desyatova, Jason N. Mactaggart, Alexey Kamenskiy

Department of Mechanical and Materials Engineering: Faculty Publications

Planar biaxial testing is commonly used to characterize the mechanical properties of arteries, but stresses associated with specimen flattening during this test are unknown. We quantified flattening effects in human femoropopliteal arteries (FPAs) of different ages, and determined how they affect the calculated arterial physiologic stress-stretch state. Human FPAs from 472 tissue donors (age 12-82 years, mean 53±16 years) were tested using planar biaxial extension, and morphometric and mechanical characteristics were used to assess the flattening effects. Constitutive parameters for the invariant-based model were adjusted to account for specimen flattening, and used to calculate the physiologic stresses, stretches, axial force, …

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Correlation Microanalysis Of Localized Molecular Structure And Nano-Mechanical Property Of Pvdf Based Copolymer, Wen Qian, Shuo Sun, Charles Nguyen, Stephen Ducharme, Joesph A. Turner Jan 2019

Correlation Microanalysis Of Localized Molecular Structure And Nano-Mechanical Property Of Pvdf Based Copolymer, Wen Qian, Shuo Sun, Charles Nguyen, Stephen Ducharme, Joesph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

Poly (vinylidenefluoride) (PVDF) and its copolymers, are well-recognized electroactive polymers. The PVDF polymer can crystallize in a quasi-hexagonal close-packed “β-phase” structure with the dipoles of all chains aligned with maximum spontaneous polarization [1-3]. Due to the limited availability of quantitative methods for nanoscale molecular structure and mechanical analysis, the polymer organization has not been fully optimized. For such ferroelectric polymers, the influence of nanoscale molecular structure on mechanical response is not well understood. In this paper, we demonstrate nanoscale characterization and measurement techniques, by comprehensive integrating atomic force microscopy (AFM), X-ray diffraction (XRD), nano-infrared (nanoIR) spectroscopy, nanoindentation, chemical nanoIR mapping, …

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A Game-Theoretic Approach To Share The Costs Of Cooperating Healthcare Networks, Jay M. Lightfoot Jan 2019

A Game-Theoretic Approach To Share The Costs Of Cooperating Healthcare Networks, Jay M. Lightfoot

Journal of International Technology and Information Management

The growing demand for healthcare services combined with the disarray in the health insurance market in the United States has created a situation where rival health networks are aggressively competing by building duplicate health facilities and providing redundant services in localized geographic regions. Unfortunately, this strategy can reduce the quality of patient care and decrease profits (Kaissi & Charland, 2013). A solution to this problem is for health networks to cooperate and share healthcare equipment, facilities, and personnel. Toward that end, this paper presents a game-theoretic method that can share these costs in a fair, efficient, and repeatable manner.

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Towards A Fault-Tolerant, Scheduling Methodology For Safety-Critical Certified Information Systems, Jian Lin Jan 2019

Towards A Fault-Tolerant, Scheduling Methodology For Safety-Critical Certified Information Systems, Jian Lin

Journal of International Technology and Information Management

Today, many critical information systems have safety-critical and non-safety-critical functions executed on the same platform in order to reduce design and implementation costs. The set of safety-critical functionality is subject to certification requirements and the rest of the functionality does not need to be certified, or is certified to a lower level. The resulting mixed-criticality systems bring challenges in designing such systems, especially when the critical tasks are required to complete with a timing constraint. This paper studies a problem of scheduling a mixed-criticality system with fault tolerance. A fault-recovery technique called checkpointing is used where a program can go …

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A Systematic Review Of Process Modelling Methods And Its Application For Personalised Adaptive Learning Systems, Kingsley Okoye Jan 2019

A Systematic Review Of Process Modelling Methods And Its Application For Personalised Adaptive Learning Systems, Kingsley Okoye

Journal of International Technology and Information Management

This systematic review work investigates current literature and methods that are related to the application of process mining and modelling in real-time particularly as it concerns personalisation of learning systems, or yet still, e-content development. The work compares available studies based on the domain area of study, the scope of the study, methods used, and the scientific contribution of the papers and results. Consequently, the findings of the identified papers were systematically evaluated in order to point out potential confounding variables or flaws that might have been overlooked or missing in the current literature. In turn, a critical structured analysis …

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