Mechanical Engineering Commons^™

Comparison Of 4d Phase-Contrast Mri Flow Measurements To Computational Fluid Dynamics Simulations Of Cerebrospinal Fluid Motion In The Cervical Spine, Theresia Yiallourou, Jan Robert Kroger, Nikolaos Stergiopulos, David Maintz, Bryn A. Martin, Alexander C. Bunck

Mechanical Engineering Faculty Research

Cerebrospinal fluid (CSF) dynamics in the cervical spinal subarachnoid space (SSS) have been thought to be important to help diagnose and assess craniospinal disorders such as Chiari I malformation (CM). In this study we obtained time-resolved three directional velocity encoded phase-contrast MRI (4D PC MRI) in three healthy volunteers and four CM patients and compared the 4D PC MRI measurements to subject-specific 3D computational fluid dynamics (CFD) simulations. The CFD simulations considered the geometry to be rigid-walled and did not include small anatomical structures such as nerve roots, denticulate ligaments and arachnoid trabeculae. Results were compared at nine axial planes …

Implementation Of Magnetic Resonance Elastography For The Investigation Of Traumatic Brain Injuries, Thomas Boulet

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Magnetic resonance elastography (MRE) is a potentially transformative imaging modality allowing local and non-invasive measurement of biological tissue mechanical properties. It uses a specific phase contrast MR pulse sequence to measure induced vibratory motion in soft material, from which material properties can be estimated. Compared to other imaging techniques, MRE is able to detect tissue pathology at early stages by quantifying the changes in tissue stiffness associated with diseases. In an effort to develop the technique and improve its capabilities, two inversion algorithms were written to evaluate viscoelastic properties from the measured displacements fields. The first one was based on …

Enhancing The Engineering Curriculum: Defining Discovery Learning At Marquette University, Jay R. Goldberg, Mark L. Nagurka

Biomedical Engineering Faculty Research and Publications

This paper summarizes the results of our investigation into the feasibility of increasing the level of discovery learning in the College of Engineering (COE) at Marquette University. We review the education literature, document examples of discovery learning currently practiced in the COE and other schools, and propose a Marquette COE-specific definition of discovery learn-ing. Based on our assessment of the benefits, costs, and tradeoffs associated with increasing the level of discovery learning, we pre-sent several recommendations and identify resources required for implementation. These recommendations may be helpful in enhancing engineering education at other schools.

Designing For Success: Developing Engineers Who Consider Universal Design Principles, Kimberly Edginton Bigelow

Mechanical and Aerospace Engineering Faculty Publications

Engineers must design for a diverse group of potential users of their products; however, engineering curricula rarely include an emphasis on universal design principles. This research article details the effectiveness of a design project implemented in a first-year engineering course in an effort to raise awareness of the need for engineers to be more inclusive when designing. Students were asked to apply universal design principles to redesign an engineering laboratory to make it more usable to all, including individuals with disabilities who use the room. A representative from the university’s disability services staff, as well as individuals with first-hand experience …

Changes In In Vivo Knee Contact Forces Through Gait Modification, Allison Kinney, Thor F. Besier, Amy Slider, Scott L. Delp, Darryl D. D'Lima, Benjamin J. Fregly

Mechanical and Aerospace Engineering Faculty Publications

Gait modification represents a non-invasive method for reducing knee joint loading in patients with knee osteoarthritis. Previous studies have shown that a variety of gait modifications are effective in reducing the external knee adduction moment. The external knee adduction moment is often used as a surrogate measure of medial compartment force. However, a recent study showed that reductions in the external knee adduction moment do not guarantee reductions in medial compartment loads. Therefore, direct measurement of changes in knee contact force is important for determining the effectiveness of gait modifications. A previous study found that medial thrust gait and walking …

Design, Analysis And Testing Of Haptic Feedback System For Laparoscopic Graspers In In Vivo Surgical Robots, Nikhil Salvi

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Laparo-Endoscopic Single Site (LESS) Robotics Surgery is an advanced technology in the field of Minimally Invasive Surgery (MIS). The LESS surgical robots significantly improve the surgeon’s accuracy, dexterity and visualization, and reduce the invasiveness of surgical procedure results in faster recovery time and improved cosmetic results. In a standard robotic endosurgery, the palpation of tissues is performed by laparoscopic graspers located at the end effectors. The master-slave configuration in robotic surgery leads in remote access to the operation site. Therefore, surgeon’s ability to perceive valuable sensory information is severely diminished. Sensory information such as haptics, which is essential for safe …

Toward A Gpu-Accelerated Immersed Boundary Method For Wind Forecasting Over Complex Terrain, Rey Deleon, Kyle Felzien, Inanc Senocak

Mechanical and Biomedical Engineering Faculty Publications and Presentations

A short-term wind power forecasting capability can be a valuable tool in the renewable energy industry to address load-balancing issues that arise from intermittent wind fields. Although numerical weather prediction models have been used to forecast winds, their applicability to micro-scale atmospheric boundary layer flows and ability to predict wind speeds at turbine hub height with a desired accuracy is not clear. To address this issue, we develop a multi-GPU parallel flow solver to forecast winds over complex terrain at the micro-scale, where computational domain size can range from meters to several kilometers. In the solver, we adopt the immersed …

Weightlifting Performance Is Related To Kinematic And Kinetic Patterns Of The Hip And Knee Joints, Kristof Kipp, Josh Redden, Michelle B. Sabick, Chad Harris

Mechanical and Biomedical Engineering Faculty Publications and Presentations

The purpose of this study was to investigate correlations between biomechanical outcome measures and weightlifting performance. Joint kinematics and kinetics of the hip, knee, and ankle were calculated while ten subjects performed a clean at 85% of 1-RM. Kinematic and kinetic time-series patterns were extracted with principal components analysis. Discrete scores for each time-series pattern were calculated and used to determine how each pattern was related to body-mass normalized 1-RM. Two hip kinematic and two knee kinetic patterns were significantly correlated with relative 1-RM. The kinematic patterns captured hip and trunk motions during the first pull and hip joint motion …

Kinematic And Kinetic Synergies Of The Lower Extremities During The Pull In Olympic Weightlifting, Kristof Kipp, Josh Redden, Michelle Sabick, Chad Harris

Mechanical and Biomedical Engineering Faculty Publications and Presentations

The purpose of this study was to identify multijoint lower extremity kinematic and kinetic synergies in weightlifting and compare these synergies between joints and across different external loads. Subjects completed sets of the clean exercise at loads equal to 65, 75, and 85% of their estimated 1-RM. Functional data analysis was used to extract principal component functions (PCF's) for hip, knee, and ankle joint angles and moments of force during the pull phase of the clean at all loads. The PCF scores were then compared between joints and across loads to determine how much of each PCF was present at …

Propagation Of Ultrasound Through Freshly Excised Human Calvarium, Armando Garcia Noguera

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

The propagation of ultrasound through complex biological media, such as the human calvarium, poses a great challenge for modern medicine. Several ultrasonic techniques commonly used for treatment and diagnosis in most of the human body are still difficult to apply to the human brain, in part, because of the properties of the skull. Moreover, an understanding of the biomechanics of transcranial ultrasound may provide needed insight into the problem of blast wave induced traumatic brain injury (TBI). In the present study, the spatial variability of ultrasonic properties was evaluated for relevant frequencies of 0.5, 1, and 2.25 MHz. A total …

Improving Health Care Quality And Safety: The Development And Assessment Of Laparoscopic Surgery Instrumentation, Practices And Procedures, Bernadette Mccrory

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Adverse events due to medical errors are a leading cause of death in the United States exceeding the mortality rates of motor vehicle accidents, breast cancer and AIDS. Improvements can and should be made to reduce the rates of preventable surgical errors since they account for nearly half of all adverse events within hospitals. Although minimally invasive surgery has proven patient benefits such as reduced postoperative pain and hospital stay, its operative environment imposes substantial physical and cognitive strain on the surgeon increasing the risk of error. In order to mitigate errors and protect patients, a multidisciplinary approach was taken …

Gpu-Accelerated Large-Eddy Simulation Of Turbulent Channel Flows, Rey Deleon, Inanc Senocak

Mechanical and Biomedical Engineering Faculty Publications and Presentations

High performance computing clusters that are augmented with cost and power efficient graphics processing unit (GPU) provide new opportunities to broaden the use of large-eddy simulation technique to study high Reynolds number turbulent flows in fluids engineering applications. In this paper, we extend our earlier work on multi-GPU acceleration of an incompressible Navier-Stokes solver to include a large-eddy simulation (LES) capability. In particular, we implement the Lagrangian dynamic subgrid scale model and compare our results against existing direct numerical simulation (DNS) data of a turbulent channel flow at Re_τ = 180. Overall, our LES results match fairly well with …

Computational Analysis Of Hybrid Norwood Circulation With Distal Aortic Arch Obstruction And Reverse Blalock-Taussig Shunt, Andres Ceballos, I. Ricardo Argueta-Morales, Eduardo Divo, Ruben Osorio, Christopher A. Caldarone, Alain J. Kassab, William M. Decampli

Mechanical Engineering - Daytona Beach

BACKGROUND: The hemodynamics characteristics of the hybrid Norwood (HN) procedure differ from those of the conventional Norwood and are not fully understood. We present a multi-scale model of HN circulation to understand local hemodynamics and effects of aortic arch stenosis and a reverse Blalock-Taussig shunt (RBTS) on coronary and carotid perfusion. METHODS: Four 3-dimensional models of four HN anatomic variants were developed, with and without 90% distal preductal arch stenosis and with and without a 4-mm RBTS. A lumped parameter model of the circulation was coupled to a local 3-dimensional computational fluid dynamics model. Outputs from the lumped parameter model …

Computational Fluid Dynamics In Congenital Heart Disease, William M. Decampli, I. Ricardo Argueta-Morales, Eduardo Divo, Alain J. Kassab

Mechanical Engineering - Daytona Beach

Computational fluid dynamics has been applied to the design, refinement, and assessment of surgical procedures and medical devices. This tool calculates flow patterns and pressure changes within a virtual model of the cardiovascular system. In the field of paediatric cardiac surgery, computational fluid dynamics is being used to elucidate the optimal approach to staged reconstruction of specific defects and study the haemodynamics of the resulting anatomical configurations after reconstructive or palliative surgery. In this paper, we review the techniques and principal findings of computational fluid dynamics studies as applied to a few representative forms of congenital heart disease.

Numerical And Experimental Investigation Of Vascular Suture Closure, Linxia Gu, Ananth Ram Mahanth Kasavajhala, Haili Lang, James M. Hammel

Department of Mechanical and Materials Engineering: Faculty Publications

Purpose — In order to optimize the performance of the suture for tissue closure, it is essential to develop strategies for devising new and improved techniques that can visualize and compare various suturing techniques. This paper describes an experimental and numerical investigation on the performance of sutured tissue.

Methods — In the experiments, two pieces of glutaraldehyde cross-linked bovine pericardium were sutured together through simple running suture and tensioned to study the performance of the sutured tissue. During testing, the tension load and the total displacement of the specimen were recorded. The strain field of the specimen was simultaneously captured …