Engineering Commons^™

Muscle Synergies Improve Estimation Of Knee Contact Forces During Walking, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd

Allison Kinney

This study investigates whether use of subject-specific muscle synergies can improve optimization predictions of muscle excitation patterns and knee contact forces during walking. Muscle synergies describe how a small number of neural commands generated by the nervous system can be linearly combined to produce the broad range of muscle electromyographic (EMG) signals measured experimentally. By quantifying the interdependence of individual EMG signals, muscle synergies provide dimensionality reduction for the neural control redundancy problem. Our hypothesis was that use of subjectspecific muscle synergies to limit muscle excitation patterns would improve prediction of muscle EMG patterns at the hip, knee, and ankle …

Muscle Synergy Constraints Improve Prediction Of Knee Contact Force During Gait, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd

Allison Kinney

Knowledge of patient-specific muscle and joint contact forces during activities of daily living could improve the treatment of movement-related disorders (e.g., osteoarthritis, stroke, cerebral palsy, Parkinson’s disease). Unfortunately, it is currently impossible to measure these quantities directly under common clinical conditions, and calculation of these quantities using computer models is limited by the redundant nature of human neural control (i.e., more muscles than theoretically necessary to actuate the available degrees of freedom in the skeleton). Walking is a particularly important task to understand, since loss of mobility is associated with increased morbidity and decreased quality of life. Though numerous musculoskeletal …

Evaluation Of Different Optimal Control Problem Formulations For Solving The Muscle Redundancy Problem, Friedl De Groote, Allison Kinney, Anil Rao, Benjamin Fregly

Allison Kinney

This study evaluates several possible optimal control problem formulations for solving the muscle redundancy problem with the goal of identifying the most efficient and robust formulation. One novel formulation involves the introduction of additional controls that equal the time derivative of the states, resulting in very simple dynamic equations. The nonlinear equations describing muscle dynamics are then imposed as algebraic constraints in their implicit form, simplifying their evaluation. By comparing different problem formulations for computing muscle controls that can reproduce inverse dynamic joint torques during gait, we demonstrate the efficiency and robustness of the proposed novel formulation.

Material Properties And Microstructural Characterization Of Specimens, T.J. Silverman, Allison Kinney, B. South, W. Yong, J.H. Koo

Allison Kinney

The HiQ upgrade to the 3D Systems Vanguard selective laser sintering (SLS) machine incorporates a revised thermal calibration system and new software. This paper quantifies differences in mechanical and morphological properties of specimens built first using a Vanguard HS (high-speed) system and again using the same system with the HiQ upgrade applied. Standard specimens are built from DuraForm PA material and tested for tensile modulus, tensile strength, elongation at break, flexural modulus and Izod impact strength. The design of the specimen battery, the conduction of the tests and the significance of the results are discussed. The upgrade is found to …

Synergies Controls Improve Prediction Of Knee Contact Forces And Muscle Excitations During Gait, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd

Allison Kinney

This study investigates whether use of muscle excitation controls constructed from subjectspecific muscle synergy information can improve optimization prediction of knee contact forces and muscle excitations during walking. Muscle synergies quantify how a large number of experimental muscle electromyographic (EMG) signals can be reconstructed by linearly mixing a much smaller number of neural commands generated by the nervous system. Our hypothesis was that controlling all muscle excitations with a small set of experimentally calculated neural commands would improve prediction of knee contact forces and leg muscle excitations compared to using independently controlled muscle excitations.

Comparison Of Material Properties And Microstructure Of Specimens Built Using The 3d Systems Vanguard Hs And Vanguard Hiq+Hs Sls Systems, T.J. Silverman, Allison Kinney, W. Yong, J.H. Koo

Allison Kinney

The HiQ upgrade to the 3D Systems Vanguard selective laser sintering (SLS) machine incorporates a revised thermal calibration system and new control software. The paper compares the tensile modulus, tensile strength, elongation at break, flexural modulus, Izod impact resistance and microstructure of two batteries of standard specimens built from recycled Duraform PA (Nylon 12). The first set is built on a Vanguard HS system and the second on the same system with the HiQ upgrade installed. The upgrade reduces user intervention, decreases total build time and improves surface finish. However, using the default processing parameters, tensile, flexure and impact properties …

Aeronautics Education, Research, And Industry Alliance (Aerial) Progress Report And Proposal, Brent D. Bowen

Brent Bowen

UNOAI Report 04-2

The Aeronautics Education, Research, and Industry Alliance (AERIAL), which began as a comprehensive, mufti-faceted NASA EPSCoR 2000 initiative, has contributed substantially to the strategic research and technology priorities of NASA, while intensifying Nebraska's rapidly growing aeronautics research and development endeavors. AERIAL has enabled Nebraska researchers to: (a) continue strengthening their collaborative relationships with NASA Field Centers, Codes, and Enterprises; Co) increase the capacity of higher education throughout Nebraska to invigorate and expand aeronautics research; and (c) expedite the development of aeronautics-related research infrastructure and industry in the state. Nebraska has placed emphasis on successfully securing additional funds …

Aeronautics Education, Research, And Industry Alliance (Aerial) Progress Report And Proposal, Brent D. Bowen

Brent Bowen

UNOAI Report 04-2 The Aeronautics Education, Research, and Industry Alliance (AERIAL), which began as a comprehensive, mufti-faceted NASA EPSCoR 2000 initiative, has contributed substantially to the strategic research and technology priorities of NASA, while intensifying Nebraska's rapidly growing aeronautics research and development endeavors. AERIAL has enabled Nebraska researchers to: (a) continue strengthening their collaborative relationships with NASA Field Centers, Codes, and Enterprises; Co) increase the capacity of higher education throughout Nebraska to invigorate and expand aeronautics research; and (c) expedite the development of aeronautics-related research infrastructure and industry in the state. Nebraska has placed emphasis on successfully securing additional funds …

Airborne Internet Providing Tethered Balloon System, Suvriti Dhawan, Mohit Vishal, Anmol Taploo, Amanjot Singh, Shiny Praveen Thote

Innovative Research Publications IRP India

In this paper we shall introduce a new system for providing wireless network communication over a specified area using ’lighter than air’ balloons. This technology will replace the existing fiber optic network system. This will be done by using a tethered balloon along with the payload (containing a receiver, a transmitter and a radio communication device).This payload will be suspended from the ground at an altitude (depending on the area of coverage required). Users under this area will be able to access this system directly for internet connectivity. This system can be used over large areas like universities, companies and …

Narrow-Linewidth Megahertz-Repetition-Rate Optical Parametric Oscillator For High-Speed Flow And Combustion Diagnostics, Naibo Jiang, Walter R. Lempert, Gary L. Switzer, Terrence R. Meyer, James R. Gord

Terrence R Meyer

We demonstrate the ability to generate ultra-high-frequency sequences of broadly wavelength-tunable, high-intensity laser pulses using a custom-built optical parametric oscillator pumped by the thirdharmonic output of a "burst-mode" Nd:YAG laser. Burst sequences consisting of 6-10 pulses separated in time by 6-10 Îs are obtained, with average total conversion efficiency from the 355 nm pump to the near-IR signal and idler wavelengths of 33%. Typical individual pulse output energy for the signal and idler beams is in the range of 4-6 mJ, limited by the available pump energy. Line narrowing is demonstrated by means of injection seeding the idler wave using …

Comparison Of Line-Peak And Line-Scanning Excitation In Two-Color Laser-Induced-Fluorescence Thermometry Of Oh, Stanislav Kostka, Sukesh Roy, Patrick J. Lakusta, Terrence R. Meyer, Michael W. Renfro, James R. Gord, Richard Branam

Terrence R Meyer

Two-line laser-induced-fluorescence (LIF) thermometry is commonly employed to generate instantaneous planar maps of temperature in unsteady flames. The use of line scanning to extract the ratio of integrated intensities is less common because it precludes instantaneous measurements. Recent advances in the energy output of high-speed, ultraviolet, optical parameter oscillators have made possible the rapid scanning of molecular rovibrational transitions and, hence, the potential to extract information on gas-phase temperatures. In the current study, two-line OH LIF thermometry is performed in a wellcalibrated reacting flow for the purpose of comparing the relative accuracy of various line-pair selections from the literature and …

Mhz-Rate Nitric Oxide Planar Laser-Induced Fluorescence Imaging In A Mach 10 Hypersonic Wind Tunnel, Naibo Jiang, Matthew Webster, Walter R. Lempert, Joseph D. Miller, Terrence R. Meyer, Christopher B. Ivey, Paul M. Danehy

Terrence R Meyer

Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging at repetition rates as high as 1 MHz is demonstrated in the NASA Langley 31 in. Mach 10 hypersonic wind tunnel. Approximately 200 timecorrelated image sequences of between 10 and 20 individual frames were obtained over eight days of wind tunnel testing spanning two entries in March and September of 2009. The image sequences presented were obtained from the boundary layer of a 20° flat plate model, in which transition was induced using a variety of different shaped protuberances, including a cylinder and a triangle. The high-speed image sequences captured a variety …

Simultaneous High-Speed Measurement Of Temperature And Lifetime-Corrected Oh Laserinduced Fluorescence In Unsteady Flames, Terrence R. Meyer, Galen B. King, Matthew Glusenkamp, James R. Gord

Terrence R Meyer

A means of performing simultaneous, high-speed measurements of temperature and OH lifetime-corrected laser-induced fluorescence (LIF) for tracking unsteady flames has been developed and demonstrated. The system uses the frequency-doubled and frequency-tripled output beams of an 80 MHz mode-locked Ti:sapphire laser to achieve ultrashort laser pulses (order 2 ps) for Rayleigh-scattering thermometry at 460 nm and lifetime-corrected OH LIF at 306.5 nm, respectively. Simultaneous, high-speed measurements of temperature and OH number density enable studies of flame chemistry, heat release, and flame extinction in unsteady, strained flames where the local fluorescence-quenching environment is unknown.

Single-Shot Gas-Phase Thermometry Using Purerotational Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering, Joseph D. Miller, Sukesh Roy, Mikhail N. Slipchenko, James R. Gord, Terrence R. Meyer

Terrence R Meyer

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate singleshot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecond (ns) and ps CARS, such as nonresonant background and collisional dephasing, are eliminated by selecting an appropriate time delay between the 100-fs pump/Stokes pulses and the pulse-shaped 8.4-ps probe. A time- and frequency-domain theoretical model is introduced to account for rotational-level dependent collisional dephasing and indicates that the optimal probe-pulse time delay is 13.5 ps …

Lidar Observations Of Elevated Temperatures In Bright Chemiluminescent Meteor Trails During The 1998 Leonid Shower, Xinzhao Chu, Alan Z. Liu, George Papen, Chester S. Gardner

Alan Z Liu

Seven persistent trails associated with bright fireballs were probed with a steerable Na wind/temperature lidar at Starfire Optical Range, NM during the 17/18 Nov peak of the 1998 Leonid meteor shower. These chemiluminescence trails were especially rich in Na. The average Na abundance within the trails was 52% of the background Na layer abundance, which suggests that the corresponding masses of the meteors were from 1 g up to 1 kg. CCD images show that the chemiluminescent emissions (including Na and OH) are confined to the walls of a tube, which expands with time by molecular diffusion. Lidar profiles within …

Quantitative Time-Averaged Gas And Liquid Distributions Using X-Ray Fluorescence And Radiography In Atomizing Sprays, Christopher D. Radke, J. Patrick Mcmanamen, Alan L. Kastengren, Benjamin R. Halls, Terrence R. Meyer

Terrence R Meyer

A method for quantitative measurements of gas and liquid distributions is demonstrated using simultaneous x-ray fluorescence and radiography of both phases in an atomizing coaxial spray. Synchrotron radiation at 10.1 keV from the Advanced Photon Source at Argonne National Laboratory is used for x-ray fluorescence of argon gas and two tracer elements seeded into the liquid stream. Simultaneous time-resolved x-ray radiography combined with timeaveraged dual-tracer fluorescence measurements enabled corrections for reabsorption of x-ray fluorescence photons for accurate, line-of-sight averaged measurements of the distribution of the gas and liquid phases originating from the atomizing nozzle.

Comment On Faa Rule Revision - Transport Category Aircraft, Paul F. Eschenfelder, Valter Battistoni

Paul F. Eschenfelder

No abstract provided.

Implementing And Testing A Novel Chaotic Cryptosystem, Samuel Jackson, Scott Kerlin, Jeremy Straub

Jeremy Straub

Cryptography in the domain of small satellites is a relatively new area of research. Compared to typical desktop computers, small satellites have limited bandwidth, processing power, and battery power. Many of the current encryption schemes were developed for desktop computers and servers, and as such may be unsuitable for small satellites. In addition, most cryptographic research in the domain of small satellites focuses on hardware solutions, which can be problematic given the limited space requirements of small satellites.

This paper investigates potential software solutions that could be used to encrypt and decrypt data on small satellites and other devices with …

An Intelligent Attitude Determination And Control System Concept For A Cubesat Class Spacecraft, Jeremy Straub

Jeremy Straub

An attitude determination and control system (ADCS) is used to orient a spacecraft for a wide variety of purposes (e.g., to keep a camera facing Earth or orient the spacecraft for propulsion system use). The proposed intelligent ADCS has several key features: first, it can be used in multiple modes, spanning from passive stabilization of two axes and unconstrained spin on a third to three-axis full active stabilization. It also includes electromagnetic components to ‘dump’ spin from the reaction wheels. Second, the ADCS utilizes an incorporated autonomous control algorithm to characterize the effect of actuation of the system components and, …

A Bent-Pipe Microwave Wireless Power Transfer Spacecraft For Relay To Unserved Regions, Jeremy Straub

Jeremy Straub

This paper seeks to begin a discussion about the efficacy of using a ‘bent pipe’ transmission concept (familiar to those in the communications satellite arena) for power transfer. It presents the ‘bent pipe’ concept and provides a brief qualitative consideration of the benefits of this approach. It also begins the process of quantitatively considering the efficacy of a ‘bent pipe’ mission by exploring the trade space related to frequency, antenna size and altitude.

Initial Results From The First National Survey Of Student Outcomes From Small Satellite Program Participation, Jeremy Straub

Jeremy Straub

This paper presents initial results of the first national / international survey of student participants in CubeSat and other small spacecraft programs. It aims to make portions of the results of the survey available for immediate use by the CubeSat / small spacecraft community prior to the completion of a thorough analysis of the results and consideration of correlating and prospective causation factors for various outcomes.

Design And Implementation Of Satellite Software To Facilitate Future Cubesat Development, Timothy Whitney, Jeremy Straub, Ronald Marsh

Jeremy Straub

The OpenOrbiter project is a campus-wide effort at the University of North Dakota to design and build a low-cost CubeSat-class satellite. The intent is to create a publically- available framework that allows a spacecraft to be built with a parts cost of less than USD $5,000 (excluding mission payload-specific costs). This paper focuses on OpenOrbiter’s software system methodology and implementation.

Current work seeks to create a generalized framework that other CubeSat developers can use directly or alter to suit their mission needs. It discusses OpenOrbiter’s overall design goals with an emphasis on software design. The software architecture is divided into …

Software Design For An Intelligent Attitude Determination And Control System, Matthew Russell, Jeremy Straub

Jeremy Straub

Space exploration and satellite missions often carry equipment that must be accurately pointed towards distant targets, therefore making an effective attitude determination and control system (ADCS) a vital component of almost every spacecraft. However, the effectiveness of the ADCS could decrease drastically if components shift during launch, degrade in efficiency over the course of the mission, or simply fail. Prior work [0] has presented a concept for a adaptive ADCS which can respond to changing spacecraft conditions and environmental factors. This poster presents an implementation for a lazy learning ADCS is presented that uses past maneuver data to construct and …

Testing A Novel Cryptosystem For Use In Securing Small Satellite Communications, Samuel Jackson, Scott Kerlin, Jeremy Straub

Jeremy Straub

Cryptography in the domain of Small Satellites is a topic of growing importance. While large satellites are likely to have the hardware requirements to run common cryptographic algorithms, small satellites are extremely limited in both hardware capabilities, which limits the speed and security of cryptosystems implemented in software, and available physical space, which limits the ability to include cryptosystems implemented in hardware. However, small satellites are growing in popularity, and as such securing communications becomes a necessity for some. The Department of Defense is exploring the possibility of using CubeSats, a type of small satellite, in their operations, as are …

Improving Satellite Security Through Incremental Anomaly Detection On Large, Static Datasets, Connor Hamlet, Matthew Russell, Jeremy Straub, Scott Kerlin

Jeremy Straub

Anomaly detection is a widely used technique to detect system intrusions. Anomaly detection in Intrusion Detection and Prevent Systems (IDPS) works by establishing a baseline of normal behavior and classifying points that are at a farther distance away as outliers. The result is an “anomaly score”, or how much a point is an outlier. Recent work has been performed which has examined use of anomaly detection in data streams [1]. We propose a new incremental anomaly detection algorithm which is up to 57,000x faster than the non-incremental version while slightly sacrificing the accuracy of results. We conclude that our method …

Unlocking The Mysteries Of Flight: From The Top Down, Juan Merkt

Juan R. Merkt

Traditionally, principles of flight are taught from the bottom-up. That is, we start by examining underlying causes (properties of air) and later move up to top consequences (aircraft performance). This traditional approach is analogous to that used by airplane designers and is most obvious in theory of flight textbooks for pilots. The problem with a bottom-up approach is that it introduces basic concepts as isolated “parts” without providing a “big picture” context. This can lead to poor understanding among student pilots. I suggest an opposite approach. Rather than starting with the underlying causes of flight, we can unravel basic principles …

Towards Real-Time, On-Board, Hardware-Supported Sensor And Software Health Management For Unmanned Aerial Systems, Johann M. Schumann, Kristin Y. Rozier, Thomas Reinbacher, Ole J. Mengshoel, Timmy Mbaya, Corey Ippolito

Ole J Mengshoel

The Openorbiter Cubesat As A System-Of-Systems (Sos), Sofiane Chaieb, Michael Wegerson, Jeremy Straub, Ronald Marsh, Benjamin Kading, David Whalen

Jeremy Straub

This paper discusses the use of the system-of-systems (SoS) methodology and SoS engineering (SoSE) to the challenge of the design and operation of a CubeSat-class spacecraft. It considers this in the context of one critical component system, the electrical power system (EPS) which interacts with virtually all other systems onboard the spacecraft. The spacecraft is also considered in the context of being a system-component of a larger mission system-of-systems. The efficacy of SoSE use for this endeavor is considered and recommendations are made for the use of SoS and SoSE by other small spacecraft and, more broadly, spacecraft developers.

Compact Kinetic Models For Typical And Alternative Aviation Turbine Fuels And Their Surrogates, Sang Hee Won, Jeffrey S. Santner, Francis M. Haas, Frederick L. Dryer, Stephen Dooley

Francis (Mac) Haas

Rate Coefficients For H+No2→Oh+No From High Pressure Flow Reactor Experiments, Francis M. Haas, Frederick L. Dryer

Francis (Mac) Haas