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Full-Text Articles in Engineering

Highly Vented Truss Wall Honeycomb Structures, David J. Sypeck Dec 2017

Highly Vented Truss Wall Honeycomb Structures, David J. Sypeck

Publications

A vented honeycomb structure with a plurality of honey­comb cells arranged in a hierarchical order and having a plurality of truss walls, each truss wall including a plurality of members. The vented honeycomb structure is fabricated by joining a plurality of sheets of trusses using any one of an expansion, a corrugation, and a slotting process. Fabri­cation can also occur by deposition, casting, additive, extru­sion, or aligning and joining methods. The honeycomb cells, truss walls, truss wall openings, and truss wall members can be functionally graded.


A Globally Stable Attractor That Is Locally Unstable Everywhere, Phanindra Tallapragada, Senbagaraman Sudarsanam Dec 2017

A Globally Stable Attractor That Is Locally Unstable Everywhere, Phanindra Tallapragada, Senbagaraman Sudarsanam

Publications

We construct two examples of invariant manifolds that despite being locally unstable at every point in the transverse direction are globally stable. Using numerical simulations we show that these invariant manifolds temporarily repel nearby trajectories but act as global attractors. We formulate an explanation for such global stability in terms of the ‘rate of rotation’ of the stable and unstable eigenvectors spanning the normal subspace associated with each point of the invariant manifold. We discuss the role of this rate of rotation on the transitions between the stable and unstable regimes.


A Sustainable Approach For Tungsten Carbide Synthesis Using Renewable Biopolymers, Monsur Islam, Rodrigo Martinez-Duarte Sep 2017

A Sustainable Approach For Tungsten Carbide Synthesis Using Renewable Biopolymers, Monsur Islam, Rodrigo Martinez-Duarte

Publications

Here we present a sustainable, environment-friendly and energy-efficient approach for synthesis of porous tungsten carbide (WC). A biopolymer-metal oxide composite featuring iota-carrageenan, chitin and tungsten trioxide (WO3) was used as the precursor material. The reaction mechanism for the synthesis of WC was estimated using the results from X-ray diffraction characterization (XRD). A synthesis temperature of 1300 °C and dwell time of 3 h were found to be the optimum process parameters to obtain WC>98% pure. The grain size, porosity and Brunauer–Emmett–Teller (BET) surface area of the synthesized WC were characterized using field emission scanning electron microscopy, high resolution transmission …


Assessing The Importance Of The Root Mean Square (Rms) Value Of Different Waveforms To Determine The Strength Of A Dielectrophoresis Trapping Force, Jordan Gilmore, Monsur Islam, Josie Duncan, Rucha Nato, Rodrigo Martinez-Duarte May 2017

Assessing The Importance Of The Root Mean Square (Rms) Value Of Different Waveforms To Determine The Strength Of A Dielectrophoresis Trapping Force, Jordan Gilmore, Monsur Islam, Josie Duncan, Rucha Nato, Rodrigo Martinez-Duarte

Publications

No abstract provided.


Assessing The Importance Of The Root Mean Square (Rms) Value Of Different Waveforms To Determine The Strength Of A Dielectrophoresis Trapping Force, Jordon Gilmore, Monsur Islam, Josie Duncan, Rucha Natu, Rodrigo Martinez-Duarte May 2017

Assessing The Importance Of The Root Mean Square (Rms) Value Of Different Waveforms To Determine The Strength Of A Dielectrophoresis Trapping Force, Jordon Gilmore, Monsur Islam, Josie Duncan, Rucha Natu, Rodrigo Martinez-Duarte

Publications

No abstract provided.


Optimizing Jets For Wake Control Of Ground Vehicles, Domenic Barsotti, Sandra Boetcher Mar 2017

Optimizing Jets For Wake Control Of Ground Vehicles, Domenic Barsotti, Sandra Boetcher

Publications

A system of wake control for a ground vehicle to help promote increased fuel efficiencies of the ground vehicle by modifying an air flow wake generated during the movement of the vehicle in a forward direction. The system includes at least one slot jet configured to be located along a rear profile portion of the ground vehicle. The at least one slot jet is configured to provide a continuous flow of air at a non-zero velocity when the ground vehicle is moving in a forward direction, the non-zero velocity being at least partially directed in a rearward direction with an …


Fabrication Challenges And Perspectives On The Use Of Carbon-Electrode Dielectrophoresis In Sample Preparation, Rodrigo Martinez-Duarte Mar 2017

Fabrication Challenges And Perspectives On The Use Of Carbon-Electrode Dielectrophoresis In Sample Preparation, Rodrigo Martinez-Duarte

Publications

The focus of this review is to assess the current status of three-dimensional (3D) carbon-electrode dielectrophoresis (carbonDEP) and identify the challenges currently preventing it from its use in high-throughput applications such as sample preparation for diagnostics. The use of 3D electrodes over more traditional planar ones is emphasised here as a way to increase the throughput of DEP devices. Glass-like carbon electrodes are derived through the carbonisation of photoresist structures made using photolithography. These biocompatible carbon electrodes are not ideal electrical conductors but are more electrochemically stable than noble metals such as gold and platinum. They are also significantly less …


Effects Of Microstructure On The Strain Rate Sensitivity Of Advanced Steels, Rakan Alturk, Steven Mates, Zeren Xu, Fadi Abu-Farha Feb 2017

Effects Of Microstructure On The Strain Rate Sensitivity Of Advanced Steels, Rakan Alturk, Steven Mates, Zeren Xu, Fadi Abu-Farha

Publications

The dependence of the strain rate sensitivity of advanced ~1 GPa tensile strength steels on the phases present in their microstructures was studied by testing different steels at 0.005 and 500 s−1. The high strain rate tests were performed using a Kolsky bar setup, while the quasi-static tests were performed using a universal testing machine. The two main steels of interest were the Ferrite-Martensite DP980 and the Ferrite-Martensite-Austenite QP980; the latter being a transformation induced plasticity (TRIP) assisted steel. For comparison, ferritic CR5 mild steel and austenitic stainless steel 201 were also tested under the same conditions. Though …


Trustworthiness Requirements For Manufacturing Cyber-Physical Systems, Radu F. Babiceanu, Remzi Seker Jan 2017

Trustworthiness Requirements For Manufacturing Cyber-Physical Systems, Radu F. Babiceanu, Remzi Seker

Publications

Distributed manufacturing operations include cyber-physical systems vulnerable to cyber-attacks. Long time not considered a priority, cybersecurity jumped to the forefront of manufacturing concerns due to the need to network together legacy, newer equipment, and entire operation centers. This paper proposes trustworthiness solutions for integrated manufacturing physical-cyber worlds, where trustworthiness is defined to complement system dependability requirements with cybersecurity requirements, such that the resulting manufacturing cyber-physical system delivers services that can justifiably be trusted. Acknowledging the inevitability of cyber-attacks, the paper models the cybersecurity component using the resilient systems framework, where system resilience is viewed as preservation of a required state …


Demisting Using An Ultrasonic Standing Wave Field, T. M. Merrell, John Saylor Jan 2017

Demisting Using An Ultrasonic Standing Wave Field, T. M. Merrell, John Saylor

Publications

Removing drops from an air flow can be challenging, particularly, for small drops. Herein a method for demisting is presented that employs ultrasonics to force small drops to combine. Specifically, a cylindrical ultrasonic standing wave field is established in a tube, forming pressure nodes that take the form of cylinders located within the tube and having the same axis as the tube. Droplets are driven toward these pressure nodes by the acoustic radiation force, forcing smaller drops to combine to form larger drops, which eventually fall due to gravity, thereby demisting the flow. Experiments presented herein show that, for the …