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Implantable photoelectronic charging(I-PEC)for medical implants

Energy Reviews 2022年第2期1卷 60-69页

作者： Kai Wang Sumanta Kumar Karan Mohan Sanghadasa Congcong Wu Shashank Priya Department of Materials Science and Engineering Pennsylvania State UniversityUniversity ParkPA16802United States Materials Research Institute Pennsylvania State UniversityUniversity ParkPA16802United States U.S.Army Combat Capabilities Development Command Aviation&Missile Center Redstone ArsenalAlabama35898United States Key Laboratory for the Green Preparation and Application of Functional Materials Hubei Key Laboratory of Polymer MaterialsSchool of Materials Science and EngineeringHubei UniversityWuhan430062China

Medical implants with functionalities such as sensing,health monitoring,stimulation,diagnosis,and physiological treatment are rapidly *** the increasing functional sophistication and addition of modules such as data transmission,on-chip processing,and data storage,energy demand of the implantable system is also *** implantable energy harvester either to recharge or ultimately replace hazardous battery is essential to provide a long-term sustainable *** harvesting techniques using piezoelectric,thermoelectric,radio frequency power transmission,biofuel,and photoelectronic(or sometimes termed as“photovoltaic”in terms of solar light harvesting,i.e.,PV)conversion,have been attempted for the implantable,but these methods are currently limited by insufficient power output,large footprint,and low ***,the planar PV with potential of lighter weight,higher energy density,and higher efficiency,provides promising power solution for in-body medical *** this short review,we will discuss the potential opportunities and challenges associated with PV's for medical implants,covering materials,to devices,and to system level requirements.

关键词： photoelectron harvesting charging

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Model Predictive Control of Combustion Phasing in Compression Ignition Engines by Coordinating Fuel Injection Timing and Ignition Assist

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IFAC-PapersOnLine 2022年第24期55卷 90-96页

作者： Omar Y. Ahmed Robert J. Middleton Vivian Tran Andrew Weng Anna G. Stefanopoulou Kenneth S. Kim Chol-Bum M. Kweon Department of Mechanical Engineering University of Michigan - Ann Arbor Ann Arbor MI 48109 U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving Ground MD 21005

Internal combustion engines may use ignition assisting heating elements such as glow plugs to facilitate combustion control in automotive or aircraft powertrains that operate with synthetic fuels of varying ignition behavior or at extreme inlet conditions. This work presents a model predictive controller (MPC) that regulates combustion phasing in compression ignition engines on a cycle-to-cycle basis by coordinating fuel start of injection (SOI) with power supplied to a glow plug acting as an ignition assist (IA) device, while enforcing IA actuator range and rate constraints. Simulations were conducted using a nonlinear virtual engine informed by data from a commercial engine operating at a condition that induced high combustion variability. A rate-based MPC formulation leveraging state estimate feedback and integral setpoint tracking was developed. Simulation results show the MPC scheme ensures steady-state tracking of combustion phasing within 70 engine cycles, conserves IA usage whenever possible to reduce thermo-mechanical stress on the actuator, and maintains closed-loop combustion variability at only 4% higher than the open-loop system variability. Furthermore, the controller maintains reference tracking even if combustion sensitivity to the actuators deviates by more than 20% from the controller's internal model, without the need for retuning control parameters.

关键词： Model predictive control internal combustion engine control ignition assist

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Mechanical Characterization and Production of Complex Shapes Using Continuous Carbon Fiber Reinforced Thermoset Resin Based 3d Printing

SSRN

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SSRN 2023年

作者： Islam, Md. Zahirul Rahman, Md. Atikur Gibbon, Luke Hall, Eric Ulven, Chad A. La Scala, John J. Mechanical Engineering Department College of Engineering North Dakota State University NDSU Dept 2490 PO Box 6050 FargoND58108 United States Combat Capabilities Development Command Army Research Laboratory FCDD-RLW-MD AberdeenMD United States

Due to its design flexibility and superior mechanical strength, 3D printing of continuous carbon fiber-reinforced polymer composites has received significant attention in recent years. However, 3D printing of continuous carbon fiber reinforced thermoset composites has suffered from limitations in reliability and repeatability. Light-assisted 3D printing enables the printing of commercially available thermoset resins, which have lower viscosity, with continuous fiber reinforcement. However, printing complex objects with dimensional accuracy is challenging with low-viscosity thermoset resins. The objective of this study was to discuss and implement new design considerations for 3D printing dimensionally accurate objects using thermoset resins with continuous carbon fiber reinforcement. The printed composite specimens exhibited high fiber volume fractions (i.e. 18%) compared to current commercial systems available. Mechanical characterization of the printed specimens showed comparable strength with conventionally manufactured composites. Due to the excellent wet-out of the fiber with the matrix resin, the printed composites showed higher interlaminar shear strength as compared to thermoplastic counterparts. Additionally, this study demonstrated a new approach for 3D printing complex shapes and grid structures using low-viscosity resin through a light-assisted printing process. © 2023, The Authors. All rights reserved.

关键词： 3D printing

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Modeling of the blade crossover interaction using machine learning 77

Modeling of the blade crossover interaction using machine le...

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77th Annual Vertical Flight Society Forum and Technology Display: The Future of Vertical Flight, FORUM 2021

作者： Sharma, Kalki Surenderan, Vidullan Yu, Yin Huang, Daning Brentner, Kenneth Anusonti-Inthra, Phuriwat Department of Aerospace Engineering Penn State University University ParkPA United States U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving GroundMD United States

ISBN: (纸本)9781713830016

Currently, 3D Computational Fluid Dynamic (CFD) rotorcraft simulations are able to account for blade crossover interaction (BCI) events, which are impulsive loading events that have a large influence on the vibrations and acoustics of a vehicle. Unfortunately, lower fidelity models are unable to adequately predict the BCI events and 3D CFD simulations are computationally expensive. This paper proposes a surrogate model that is able to predict the BCI event with reasonable accuracy and high computational efficiency for a subset of operating conditions. A dataset was created using transient 2D CFD simulations of airfoils moving toward each other in close proximity. The Mach number, angle-of-attack of each airfoil, along with the vertical separation distance between airfoils was varied in each simulation. An additional dependent parametric input (airfoil horizontal separation distance) was recorded along with the transient loads on the airfoils. This dataset was used in a supervised manner to train univariate (UV) and multivariate (MV) implementations of the Gaussian Process Regression model. Given airfoil operating conditions, the models are able to predict the BCI events. Hyper-parameters such as kernels and trend functions were compared using 5-fold cross validation and the final MV and UV models were compared on a held out test set to demonstrate predictive performance on unseen data. © 2021 by the Vertical Flight Society.

关键词： Forecasting

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MLE of Banded, Spiked, High-Dimensional Clutter Covariance–A Convex Relaxation Approach

MLE of Banded, Spiked, High-Dimensional Clutter Covariance–...

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IEEE International Conference on Radar

作者： Shashwat Jain Vikram Krishnamurthy Muralidhar Rangaswamy Sandeep Gogineni Sean M. O'Rourke Bosung Kang Electrical and Computer Engineering Cornell University Ithaca NY USA Air Force Research Laboratory Wright Patterson AFB OH USA Information Systems Laboratories Inc. Dayton OH USA Army Research Laboratory U.S. Army Combat Capabilities Development Command Adelphi MD USA University of Dayton Dayton OH USA

ISBN: (数字)9798331539566

ISBN: (纸本)9798331539573

In high-dimensional Space-Time Adaptive Processing (STAP), accurate estimation of the clutter-plus-noise covariance matrix is challenging, especially in low-sample regimes where traditional estimator like the Sample Covariance Matrix (SCM) becomes unstable. To address this challenge, we model the clutter-plus-noise covariance matrix as a “Banded+Spiked” covariance matrix. This model assumes that the clutter covariance matrix has a banded structure, while the singular values of the clutter-plus-noise covariance matrix are predominantly influenced by the noise floor. This aligns with a spiked covariance model, which effectively captures the dominant spiked characteristics of the clutter-plus-noise covariance matrix. We demonstrate that the Maximum Likelihood Estimation (MLE) problem for this estimation task is non-convex and therefore we propose a convex relaxation of the MLE. Our relaxation is formulated as a Frobenius loss minimization with non-smooth convex constraints that enforce banded sparsity in the covariance matrix. The proposed optimization algorithm jointly estimates both the banded clutter covariance matrix and the noise power. Numerical results using the high-fidelity RFView radar simulation environment show that our algorithm achieves a higher Signal-to-Clutter-plus-Noise Ratio (SCNR) compared to existing state-of-the-art methods, including TABASCO, Spiked Covariance Stein Shrinkage, and Diagonal Loading.

关键词： Maximum likelihood estimation Adaptation models Radar clutter Radar detection Minimization Covariance matrices Clutter Optimization Signal to noise ratio Periodic structures

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Eutectic, precipitation-strengthened alloy via laser fusion of blends of Al-7Ce-10Mg (wt.%), Zr, and Sc powders

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Acta Materialia 2023年第1期246卷

作者： Ekaputra, Clement N. Weiss, David Mogonye, Jon-Erik Dunand, David C. Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Eck Industries ManitowocWI54220 United States U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving Ground MD21005 United States

Laser powder-bed fusion was used to create an Al-7Ce-10Mg-0.71Zr-0.23Sc (wt.%) alloy, using hypoeutectic Al-7Ce-10Mg (wt.%) pre-alloyed powder blended with either elemental Zr and Sc powders (∼20 µm in size), or pre-alloyed, concentrated Al-10Zr and Al-10Sc (wt.%) powders (comprised of 1-5 µm Al3Zr or Al3Sc particles embedded in a 3Zr, Al3Sc vs. 1850 and 1541°C for Zr, Sc) of the dissolving species. The alloys fabricated with prealloyed powders display larger amounts of very fine grains (1-2 µm) nucleated by primary L12 Al3(Zr,Sc) precipitates, and a clear hardening response during aging, consistent with supersaturated Zr and Sc forming a high number density of secondary L12 Al3(Zr,Sc) nanoprecipitates. © 2023

关键词： Aluminum alloys

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Non-Intrusive Estimation of In-Cylinder Pressure and Combustion Parameters Using an External Accelerometer

SSRN

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SSRN 2023年

作者： Jeon, Woongsun Georgiou, Anastasis Sun, Zongxuan Rothamer, David A. Kim, Kenneth Kweon, Chol-Bum Rajamani, Rajesh Combat Capabilities Development Command's Army Research Laboratory United States School of Electrical and Electronics Engineering Chung-Ang University Seoul06974 Korea Republic of Department of Mechanical Engineering University of Minnesota MinneapolisMN55455 United States Department of Mechanical Engineering University of Wisconsin-Madison MadisonWI53706 United States Army Research Laboratory United States

This paper develops a new approach to estimation of in-cylinder pressure and combustion variables in a diesel engine using measurements from a non-intrusive accelerometer. The new estimation approach is based on separating the combustion component of the acceleration signal from the non-combustion component. Only the combustion component of the acceleration is well correlated with the combustion component of in-cylinder pressure. A first order differential equation model between these combustion components is proposed and used to estimate in-cylinder pressure. The combustion component of acceleration is obtained by using a finite impulse response model and a real-time adaptive least squares algorithm that utilizes the crankshaft speed signal to find and subtract the speed-related component of the acceleration measurement. The proposed method is evaluated experimentally using a turbocharged high speed 4-cylinder compression-ignition direct-injection (CIDI) engine and over 85 data sets of different operating conditions involving both single and double (pilot and main) injections. © 2023, The Authors. All rights reserved.

关键词： Accelerometers

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High-pressure fuel spray ignition behavior with hot surface interaction 38th

High-pressure fuel spray ignition behavior with hot surface ...

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38th International Symposium on Combustion, 2021

作者： Motily, Austen H. Ryu, Je Ir Kim, Keunsoo Kim, Kenneth Kweon, Chol-Bum M. Lee, Tonghun Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 United States Vehicle Technology Directorate Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving Ground MD 21005 United States

Fuel-flexible aircraft propulsion systems using compression ignition engines will require novel strategies for reducing the ignition delay of low-reactivity fuels to feasible timescales. Hot surface ignition of fuel sprays has been implemented in some practical situations, but the complex nature of flame formation within the spray structure poses significant challenges. To design next-generation ignition devices, the capacity of hot surface heating elements to promote fuel spray ignition must be investigated. In this study, a rapid compression machine was used to examine the ignition process of a single kerosene-based F-24 jet fuel spray with a cylindrical heating element inserted into the spray periphery. The effects of both heating element surface temperature and insertion depth on the ignition characteristics of the F-24 fuel sprays were investigated under reduced temperature and pressure conditions for compression ignition engines. Experiments were conducted with moderately high injection pressures of 40 MPa. Results showed two modes of ignition governed by surface temperature and insertion depth of the heating element. An optimal position was determined where the heating element tip is located in the fuel vapor cone around the liquid spray. For this configuration, a critical surface temperature was identified (∼1250 K), above which short ignition delays associated with a “spray ignition” mode are consistently achieved. In this case, a local ignition flame kernel propagates downstream to the flame lift-off length before full ignition of the spray. In comparison, below the critical temperature a slower “volumetric” mode was observed. The extended ignition delays associated with this mode may be impractical for compression ignition engines operating at high speeds and increased altitude.

关键词： Ignition

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Hybrid Integration of Semiconductor Lasers: Impact of Matching Laser AR Coatings to Photonic Wire Bonds

Hybrid Integration of Semiconductor Lasers: Impact of Matchi...

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2024 Conference on Lasers and Electro-Optics, CLEO 2024

作者： Esmaeeli, Omid Mitchell, Matthew Bickford, Justin Grillot, Frederic Chrostowski, Lukas Shekhar, Sudip Department of Electrical and Computer Engineering The University of British Columbia VancouverBC Canada Stewart Blusson Quantum Matter Institute The University of British Columbia VancouverBC Canada Dream Photonics Inc. VancouverBC Canada Army Research Laboratory US Army Combat Capabilities Development Command AdelphiMD United States LTCI Telecom Paris Institute Polytechnique de Paris Palaiseau91120 France Center for High Technology Materials University of New Mexico AlbuquerqueNM87106 United States Dream Photonics Inc. WoodinvilleWA United States

We investigate the influence of anti-reflection (AR) coating index on the performance of distributed feedback (DFB) lasers when integrated to a fiber using photonic wire bonds (PWBs). We compare the performance of air... 详细信息

ISBN: (纸本)9781957171395

关键词： Distributed feedback lasers

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A Constraint-Driven Approach to Line Flocking: The V Formation as an Energy-Saving Strategy

arXiv

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arXiv 2022年

作者： Beaver, Logan E. Kroninger, Christopher Dorothy, Michael Malikopoulos, Andreas A. The Division of Systems Engineering Boston University BostonMA United States Combat Capabilities Development Command Army Research Laboratory MD United States The Department of Mechanical Engineering University of Delaware NewarkDE United States

The study of robotic flocking has received significant attention in the past twenty years. In this article, we present a constraint-driven control algorithm that minimizes the energy consumption of individual agents and yields an emergent V formation. As the formation emerges from the decentralized interaction between agents, our approach is robust to the spontaneous addition or removal of agents to the system. First, we present an analytical model for the trailing upwash behind a fixed-wing UAV, and we derive the optimal air speed for trailing UAVs to maximize their travel endurance. Next, we prove that simply flying at the optimal airspeed will never lead to emergent flocking behavior, and we propose a new decentralized "anseroid" behavior that yields emergent V formations. We encode these behaviors in a constraint-driven control algorithm that minimizes the locomotive power of each UAV. Finally, we prove that UAVs initialized in an approximate V or echelon formation will converge under our proposed control law, and we demonstrate this emergence occurs in real-time in simulation and in physical experiments with a fleet of Crazyflie quadrotors. Copyright © 2022, The Authors. All rights reserved.

关键词： Multi agent systems

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