bluuebunny/crossref_metadata_2025 huggingface dataset:
The Optimal Formation Condition of the Axis-Symmetry Cyclic Vortex Rings
Authors: Akagi Fujio , Hifumi Kazuki , Mizuki Katsuya , Ando Youichi , Yamaguchi Sumio
Published: July 2018

The cyclic vortex rings, which are generated cyclically by a pulsating jet, appear to be an effective method for particles and fluids transport. In order to identify the formation conditions of cyclic vortex rings that are optimal for transport, the effect of the formation conditions of cyclic vortex rings, such as the velocity pulsation amplitude, period and acceleration of jet pulsation conditions, and conditions of including intermittent period, on the axis symmetry characteristics of behavior of vortex rings is investigated experimentally. The results indicate that the axis symmetry characteristics of cyclic vortex rings begin to loss by the following four factors, the influence of separated vortex rings, the influence of trailing vortex rings, the influence of trailing vortex rings formed in the previous cycle, and the influence of the cyclic vortex ring formed in the previous cycle. The behavior of cyclic vortex rings can be classified into three types, and is determined by the combination of loss-inducing factors and their individual strengths. We also discuss the formation conditions of cyclic vortex rings that are optimal for transport.
A Tubular Cross-Flow Filtration Module Based on Chaotic Advection
Authors: Kang T. G. , Park K. T. , Kim S. U.
Published: July 2018

We propose a tubular membrane module with embedded three-dimensional structures which is efficient in a wide range of operating conditions (covering both laminar and turbulent flows). Thin plates with barriers are inserted periodically in the circular channel geometry, leading to chaotic advection in a spatially periodic channel flow. Using a numerical scheme combining a particle-tracking and the finite element method, the insert geometry is optimized. The performance of the newly proposed membrane module is assessed by experiments. The membrane module with embedded inserts is found to be better in performance than an ordinary tubular membrane module.
Experimental Investigation of Single Phase Pressure Drop in a Plate Heat Exchanger
Authors: Khan Tariq S. , Khan Mohammad S. , Ayub Zahid H.
Published: July 2018

Pressure drop characteristics of a gasketed commercial plate heat exchanger (PHE) configured for single phase water to water flow application are presented. Isothermal pressure drop data are provided for two symmetric 30°/30°, 60°/60° and a non-symmetric 30°/60° (mixed) chevron plate configuration in the plate heat exchanger. Reynolds number was varied from 500 to 2,500. The experimental data are found to be a strong function of chevron angle and Reynolds number. Performance evaluation results show that mixed plate configuration can be a choice in optimizing the PHE design for improved performance.
Measurement of the Wall Shear Stress With Sublayer Thin Plate of Thermochromic Liquid Crystal
Authors: Kodama Takashi , Mochizuki Shinsuke
Published: July 2018

New optical method for measurement of the local wall shear stress has been developed by using thermo-chromic liquid crystal temperature measurement based on hue [1], [2] of the camera view. The flow field is the fully developed turbulent channel flow. Thin film made of thermo-chromic liquid crystal is placed on the wall. A rectangular shaped obstacle is glued on the film. The obstacle is within a region of buffer layer with height from the wall. Temperature of the film and the obstacle are slightly raised by a heater below the wall. The air flow makes non-uniform temperature distribution and non-uniform color distribution appears on the surface of the film. Relations between hue and local skin friction coefficient were examined in a turbulent air channel flow. It is indicated that a certain hue of a point is varying linearly against the corresponding local skin friction coefficient.
Effects of System Rotation on Disturbances Injected Into Laminar Flow
Authors: Iida Oaki , Aono Yosuke
Published: July 2018

Effects of system rotation are investigated on inhomogeneous flow where disturbances are transported from turbulent to non-turbulent flow field through advection and turbulent diffusion. With the body force on the fringe region, spectral method is used for inhomogeneous flow which is stirred at the bottom of the cuboid computational box. As a result, it is found that inertial waves with a constant helicity are transmitted in the direction perpendicular to the stirred surface, and parallel to rotational axis. In this study, the effects of system rotation on generation and propagation of wave are discussed.
The Numerical Analysis of Control Effect on Cavitation Instabilities in a Cascade With a Random Slit
Authors: Hagiwara Ryosuke , Iga Yuka
Published: July 2018

In the present study, numerical analysis was carried out around the a cyclic flat-plate cascade with a random slit, so as to examine the suppressing or controlling effect of the slit for cavitation instabilities such as a cavitation surge and rotating cavitation. These instabilities cause various problem for the turbomachinery, for example, rotating cavitation causes an asynchronous axial vibration, and cavitation surge causes a pulsation of working fluid by resonance phenomenon of the system. Especially, in liquid propellant rocket engine, suppression process for these instabilities bring increase in cost of the launch. Therefore, it is thought that to find effective suppression technique is significant for turbomachinery.

In this paper, two types of the flat-plate three blades cascade which has a slit at different position (herein called “random slit”) was analyzed, and the results ware compared with the result of cascade without slit. As a result, the cavitation surge is perfectly suppressed in both of two types cascade with a random slit. Also, in the one case of them, sub-synchronous rotating cavitation and rotating stall cavitation is suppressed. Furthermore, super-synchronous rotating cavitation which is not observed in single-stage cascade, is detected by arranging a random slit. These results indicate the possibility of suppressing cavitation instabilities or controlling the type of the cavitation instabilities by the arrangement of the slit. Moreover, the head performance at the almost same cavitation number is equal or slightly increasing by arranging the random slit.
Internal Flow Condition of Fluid Food Pump Using Semi-Open Impeller
Authors: Shigemitsu Toru , Shinohara Hirotaka , Matsubara Takumi , Fukutomi Junichiro
Published: July 2018

Fluid machineries for fluid food have been used in wide variety of field i.e. transportation, filling, and improvement of quality of fluid food. Although, flow conditions of these are quite complicated because fluid food is different from water. Therefore, a design method based on the internal flow conditions is not conducted. In this research, turbo-pump having small number of blade was used to decrease shear loss and keep wide flow passage. The flow phenomena were not clarified in detail, although, it was found that internal flow condition was complex in the test pump in previous studies. In order to investigate the complex internal flow condition, the unsteady numerical analysis using low viscous fluid was conducted. In this paper, the internal flow conditions at each axial position of the centrifugal pump having semi-open impeller were investigated by the numerical analysis results. In addition to that, the influence of the internal flow conditions on its head was clarified.
Simple Vibration Diagnosis and Experimental Verification Using Eccentricity Shaker
Authors: Oh Seung Tae , Ryu Kil-Su , Han Seung Woo , Roh Cheol Woo , Joo In Geouk , Oh Kyeong Hwan
Published: July 2018

The method of vibration diagnosis for power plant equipment is generally used the modal method using impact hammer. However, it takes a long time to measure and verify the response frequency which is associated with the specific resonant frequency. Therefore, this research deals with the simpler method comparing to the measured modal characteristics using impact hammer. To find an efficient vibration control method, the flexural response of structure and rotating machinery such as turbine, pumps, and generator which are commonly encountering in power plant equipment. The used eccentric mass shaker is a very powerful and available vibration diagnosis method to carry out forced vibration test on structures as well as rotating machines by means of generating a harmonic load. Through the experimental verification using the proposed vibration diagnosis, it is helpful and useful for site experts and practical engineers to evaluate the vibration resonance in field audits.
Bistable Energy Harvesting From Human Motion
Authors: Wang Wei , Cao Junyi , Zhou Shengxi , Lin Jing
Published: July 2018

Recently, the power supply for portable electronic devices using the electricity extracted from human motion and ambient vibrations has received considerable attention from multidiscipline field. Among many energy converting mechanisms, the ease miniaturization of piezoelectric cantilever structure propels many research groups to investigate the potential of efficient energy harvesting from ambient vibration using resonant phenomena. However, the incapability of traditional linear energy harvesting from low frequency or varying frequency vibrations has become an open issue. This paper investigates the feasibility of nonlinear energy harvesters with different bistable potential well functions in harvesting energy from walking and running vibration. The portable nonlinear energy harvesting device and its measurement system has been established to obtain the model parameter and excitation signal from human motion. The electromechanical model for bistable energy harvesters with different nonlinear restoring force is derived from theoretical method and experimental data. Numerical investigation under human walking and running vibrations shows that large amplitude interwell motion are easily achieved to improve energy output while the proper potential well function of bistable oscillators is designed. The comparative experiments for nonlinear energy devices with different potential well function are performed. The history and frequency spectrum of output voltage demonstrate the effectiveness of numerical simulation and the clear potential of bistable energy harvesting from human motion by means of appropriate potential function design.
Fault Feature Extraction for Rolling Bearing Based on Dual Impulse Morlet Wavelet
Authors: Feng Yi , Lu Bao-chun , Zhang Deng-feng , Zhang Wei
Published: July 2018

The common impulse feature model is oscillating and attenuated signal with a single maximum peak, while the formation principle of actual impulse feature is ignored. Considering the continuous dual impulse waveform feature of rolling bearing fault in the vibration signal and the matching effects of the single impulse waveform with Morlet wavelet, a “dual impulse Morlet wavelet” model is proposed. Through ant colony algorithm with the indicator of the maximum cross-correlation, 4 types of parameters are optimized adaptively which affect the similar degree between dual impulse Morlet wavelet and the dual impulse waveform intercepted from the bearing vibration signal. Then, the optimal model is obtained. The bearing fault experiment verification shows that the optimal dual impulse Morlet wavelet can effectively improve the analytical precision and energy concentration of impulse feature in both of time domain and frequency domain, which overcomes the disadvantages of Morlet wavelet effectively.
Experimental and Analytical Study of Coriolis Effects in Bladed Disk
Authors: Ruffini Valentina , Schwingshackl Christoph , Green Jeff
Published: July 2018

Modern aero-engines have reached a high level of sophistication and only significant changes will lead to the improvements necessary to achieve the economic and environmental targets of the future. Open rotors constitute a major leap in this direction, both in terms of efficiency and of technological innovation. This calls for a revision of the accepted design practices, and a new focus on phenomena that have been little investigated in the past, such as the Coriolis effect, or the gyroscopic coupling of the blades with the shaft. Experimental results from modern fans, with large blades and strong stagger angles, are showing dependence on Coriolis gyroscopic effects already, an effect that is expected to be strongly enhanced with the proposed open rotor designs.

For an accurate prediction of the Coriolis and gyroscopic effects in rotating assemblies a fully experimentally validated approach is needed. Today’s FE models can capture the basic physical phenomena, but experimental confirmation is still needed for the evolution of the mode shapes with angular speed, and the influence of damping and geometric nonlinearities when gyroscopic coupling is considered. To support this validation effort a new rotating test rig will be introduced, initial measurement data will be discussed, and a comparison with a finite element analysis presented.

Different forcing patterns, including forward and backward travelling-wave engine order excitation could be experimentally excited in the new rig, Coriolis-induced frequency splits were found in the dynamic response, showing a significant change in the dynamic behaviour of the investigated dummy disk, and only a minor impact of the mistuning was observed on the frequency splits due to Coriolis effects. The experimental results have been compared to a finite element analysis, and after some updating a good agreement between the predicted and measured Campbell diagrams could be obtained, demonstrating the reliability of the modelling approach.
Vibration-Based SHM of Ordinary Buildings: Detection and Quantification of Structural Damage
Authors: Pierdicca Alessio , Clementi Francesco , Maracci Diletta , Isidori Daniela , Lenci Stefano
Published: July 2018

One of the most important issues in civil and in mechanical engineering is the detection of structural damages, which are defined as changes of material properties, of boundary conditions and of system connectivity, which adversely affect the system’s performances. The damage identification process generally requires establishing existence, localization, type and intensity of the damage.

During its service life, a structure, besides his natural aging, can be subjected to earthquakes. These events may have a deep impact on building safety and a continuous monitoring of the structure health conditions, through Structural Health Monitoring (SHM) techniques, is necessary in many cases.

Within this a background, the purpose of this work is to propose an integrated novel approach for the diagnosis of structures after a seismic event. The proposed monitoring system is based on recording the accelerations of the real structure during a seismic input, and the reintroduction of them into a numerical model, suitably tuned, in order to outline a possible post-earthquake scenario.

This approach provides an estimation of the health of the building and of its residual life, and to detect and quantify the damage, some of the crucial aspects of SHM. Actually, we also get both online and self-diagnosis of the structural health.

The technique is applied to a real structure, an industrial building liable of some seismic vulnerabilities. It it did not undergo an earthquake, so we have not recordered accelerations, and get them from a different numerical models subjected to the ground acceleration of a realistic earthquake.
Dynamic Modeling of a Rolling Flexible Sphere
Authors: Hogan François Robert , Forbes James Richard , Walsh Alex
Published: July 2018

The motion equations of a rolling flexible spherical shell are derived using a Lagrangian formulation. The motion equations developed capture the nonholonomic nature of the flexible sphere rolling without slip on a flat surface. The free vibrations of the spherical shell are modeled using the Rayleigh-Ritz discretization method. Numerical simulations are performed to validate the dynamic model developed and to investigate the effect of the flexibility of the spherical shell on its trajectory.
Damping in a Composite Beam With a Jointed Interface
Authors: Goyder Hugh , Ind Philip , Brown Daniel
Published: July 2018

An experimental investigation has been made of two identical beams of length 750mm bolted together (a composite beam) which have contact over the whole of the neutral plane. The objective is to determine how friction between the two beams influences the damping. In one set of experiments the beams were held apart using washers while in the second set the beams could contact each other over their whole length. The number of bolts used to hold the beams together was varied between three and 17. The damping of the first two or more modes of the beams was measured. The material damping of the beams when not bolted together was also measured. It was found that the material damping and the damping of the fully bolted composite beam were very similar (damping ratio 0.0005). However, when the beams were in contact and had few bolts (just 3) and the amplitude of vibration was large the damping ratio changed to a much larger value of 0.01.

The experiments suggest that the damping due to the bolts is similar to that of material damping. It is only when other friction sites, not involving bolts, are slipping that damping becomes large.

The consequences for the designer of a built-up structure who wishes to increase damping is thus to use the smallest number of bolts and to arrange for other surfaces to be in sliding contact.
Effect of Material and Geometric Parameters on the Steady-State Belt Stresses and Belt Slip for Flat Belt-Drives
Authors: Yildiz Cagkan , Wasfy Tamer M. , Wasfy Hatem M. , Peters Jeanne M.
Published: July 2018

In order to accurately predict the fatigue life and wear life of a belt, the various stresses that the belt is subjected to and the belt slip over the pulleys must be accurately calculated. In this paper, the effect of material and geometric parameters on the steady-state stresses (including normal, tangential and axial stresses), average belt slip for a flat belt, and belt-drive energy efficiency is studied using a high-fidelity flexible multibody dynamics model of the belt-drive. The belt’s rubber matrix is modeled using three-dimensional brick elements and the belt’s reinforcements are modeled using one dimensional truss elements. Friction between the belt and the pulleys is modeled using an asperity-based Coulomb friction model. The pulleys are modeled as cylindrical rigid bodies. The equations of motion are integrated using a time-accurate explicit solution procedure. The material parameters studied are the belt-pulley friction coefficient and the belt axial stiffness and damping. The geometric parameters studied are the belt thickness and the pulleys’ centers distance.
Genetic Optimization of Geometrical Parameters of High Speed Rotor
Authors: Ghalamchi Behnam , Kłodowski Adam , Sopanen Jussi T. , Mikkola Aki M.
Published: July 2018

The main scope of this paper is optimization of high speed rotor systems by using Evolutionary Algorithm. The target of the optimization is finding geometrical parameters of the shaft, in such a way that the critical speeds are not occurring in the operation speed range. Rotating machines have a wide range of applications in industrial machinery and applying numerical optimization techniques helps engineers to improve the performance of rotor bearing systems. A schematic of a turbine rotor system is studied. The rotor is modeled using finite element method and Timoshenko beam elements having four degrees of freedom (DOF) per node — two translational and two rotational. Critical speeds are identified using Campbell diagram. The outcome of the simulation is looking to find the widest safe margin for operation speed range without any critical speed in Campbell diagram within the operation range. Design parameters for optimization are overhang shafts lengths and diameters. Several simulation runs with different variables shows a significant effect of these parameters in dynamic behavior of the system. Comparison of the results with the basic design of turbine rotor reveals that all constraints are satisfied.
Application of Nonlinear Vibration Absorbers to the Control of Piston Secondary Motion in Internal Combustion Engines
Authors: Dolatabadi Nader , Theodossiades Stephanos , Rothberg Steve J.
Published: July 2018

The impulsive behavior of piston plays a key role in the Noise, Vibration and Harshness (NVH) of internal combustion engines. There have been several studies on the identification and quantification of piston impacting action under various operation conditions. In the current study, the dynamics of piston secondary motion are briefly explored, since this is fundamental to understanding the aggressive oscillations, energy loss and noise generation. Concepts of controlling piston secondary motion (and thus, impacts) are investigated and a new passive control approach is presented based on the nonlinear energy absorption of the highly transient oscillations. The effectiveness of this new method on the improvement of piston impact behavior is discussed, using a preliminary optimization exercise (with respect to engine excitation/speed, damping and stiffness of the nonlinear oscillator) that leads to the conceptual design of a nonlinear energy absorber.
Analysis and Optimal Placement of Particle Dampers Based on Discrete Element Simulation
Authors: Li Shilong , Tang Jiong
Published: July 2018

Particle damper is formed by granular particles enclosed in a container which is attached to or embedded in a vibrating structure. The energy dissipation mechanism of a particle damper is highly nonlinear, and derived from a combination of collision/impact and friction among particles and between particles and the enclosure. Meanwhile, the coupling between particle dampers and the host structure and among multiple dampers further increases the difficulty to analyze the particle damping performance. In this paper, a new coupling method is developed to integrate the continuous host system with multiple particle dampers to analyze the energy transfer between the host structure and the dampers. The discrete element method (DEM) is employed to describe and analyze the particle motion inside each damper, which accurately accounts for various energy dissipation mechanisms of the particle damping system. In order to enhance the computational efficiency, a Verlet table combined with LC method is also used to improve the contact detection since the long time simulation is needed to perform damping analysis under a wide range of frequencies. The damping effect under different arrangements of particle dampers on a clamped-free beam is analyzed, and the results indicate that the optimal positions of dampers not only rely on the mode shape of the system, but also are dependent upon the excitation level.
Modelling the Response of Force Transducers Under Sine-Sweep Calibration
Authors: Vlajic Nicholas , Chijioke Ako
Published: July 2018

In the dynamic calibration of force transducers using swept-sine excitation, the sensitivity (the output voltage divided by the applied force) of the transducer can start to decrease (or roll-off) at higher frequencies. It has been proposed that this roll-off originates from the finite stiffness and dissipation of the transducer. In other words, the roll-off is caused by a mechanical frequency response of the transducer, and the sensitivity is proportional to this frequency response function via a constant. The focus of this study is the origin of the observed roll-off in sensitivity. The findings of this study have application to the dynamic calibration and use of force transducers.
ANSYS Simulation of Impact Reduction With Fluid-Filled Interconnected Bubble Arrays
Authors: Kumar Rajeev , Carrigan Wei , Dennis Brian H. , Yang Bo , Wijesundara Muthu B. J.
Published: July 2018

Soldiers, fire fighters, athletes in contact sports and construction workers are often exposed to severe impact conditions like blast waves and blunt force trauma. They often end up suffering injuries that have life-long consequences resulting in huge health care costs. Even the state of the art in impact reduction technology is inadequate when it comes to absorbing impact. University of Texas Arlington’s research institute (UTARI) has developed a concept for reducing impact using arrays of interconnected bubbles filled with a fluid. The array is fabricated out of a soft elastic polymer that can be used as a helmet liner. When the helmet experiences an impact, the load is effectively distributed by the movement of the fluid among the array of interconnected bubble cells. A preliminary numerical modeling to demonstrate the ability of this design concept to reduce impact loads as the proof-of-concept has been carried out. Effect of various design parameters such as secondary bubble thickness, type of fluid, connecting channel size and impact velocity has been studied in this finite element simulation using ANSYS. This paper presents the results from this preliminary study.
Semi-Analytical Boundary Collocation Technique for Wave Propagation Applications
Authors: Fu Zhuo-Jia
Published: July 2018

This study presents on a recent semi-analytical boundary collocation technique, the singular boundary method (SBM), for exterior wave propagation analysis. The SBM is mathematically simple, easy-to-program, meshless and applies the concept of source intensity factors to eliminating the singularity of the fundamental solutions and avoiding singular numerical integrals in the boundary element method. The Burton and Miller’s method is introduced to the present SBM to enhance the quality of the solution, particularly in the vicinity of irregular frequencies. Then the present SBM is applied to water wave-structure interaction with four-cylinder structure and SH wave scattering in 2D hill.
Gait Rehab Adaptive Machine: Design of GRAM, a Walking Linkage Powered Wheelchair for Lower Body Therapy and Assistance
Authors: Sarigul-Klijn Yasemin
Published: July 2018

Nearly half of individuals with stroke experience some form of long-term disability and stroke is one of the main causes of wheelchair use in the United States [1]. Early rehabilitation in the acute phase of stroke has been shown critical to promoting motor plasticity and patient outcomes. However, research shows that only 32% of the time during inpatient rehabilitation is spent in active therapy, while the rest of the time is spent on other activities around the ward [2]. For walking impairment, it is especially important for patients to experience similar force loading and practice the patterning of gait in order to recover [3]. However, in a typical therapy session focused on gait rehabilitation patients only will take about 300 steps on average. This is far below what has been thought needed for humans to learn how to walk [4].
A Passive Two-Degree-of-Freedom Ankle-Foot Prosthesis
Authors: Elley Colin , Nelson Carl A.
Published: July 2018

Natural human ankle motion includes dorsiflexion/plantarflexion (the major contributor to gait) as well as smaller contributions from inversion/eversion and abduction/adduction motions. Many of the commercially available passive prostheses for amputees are either stiff in all these motion directions or are compliant mainly in the dorsiflexion/plantarflexion direction. This can make it difficult for amputees to walk on uneven or sloped surfaces, and leads to increased risk of falling [1–4].
Finite Element Studies of Triple Actuation of Shape Memory Alloy Wires for Surgical Tools
Authors: Konh Bardia
Published: July 2018

Since the early discovery in 1951 [1], shape memory alloys (SMAs) have been used in design and development of several innovative engineering systems. SMAs’ unique characteristics have introduced unconventional alternatives in design and development of advanced devices. SMA’s field of applications has covered many areas from aerospace to auto industries, and medical devices [2]. During the past couple of decades, scientists have suggested material models to predict the SMA’s shape memory effect (SME) and its superelastic behavior. The superelastic characteristic of SMAs (its capability to exhibit a large recoverable strain) has been widely used to develop innovative products including biomedical implants such as stents, artificial heart valves, orthodontic wires, frames of indestructible spectacles, etc. However, its actuation capabilities, known as SME, hasn’t been thoroughly expanded. The number of products privileging from SMA’s SME behavior has been very limited. The reason relies on the SMA’s complex material properties that depend on the stress, strain and temperature at every stage of actuation as well as the material’s processing and the thermomechanical loading history.
Neutral Electrode Contact Quality Monitoring: Quantifying Latent Risks, Improving Testability
Authors: Friedrichs Daniel , Kuehl Paul , Lucke Lori
Published: July 2018

In high-frequency (“HF”) monopolar electrosurgery (or radio-frequency ablation), high current density causes heating of tissue adjacent to a surgical instrument. HF current passes through tissue at a frequency sufficiently high to avoid stimulation of muscle, but intentionally causes I2R heating of tissue for the purposes of ablation, dissection, and coagulation. In addition to the surgical tool, a Neutral Electrode (“NE”, often called a “ground pad”, “return electrode”, or simply “pad”) contacts the patient to complete the electrical circuit, as shown in Fig. 1.
Stent Fracture Predictions With Peridynamics
Authors: Vasenkov Alex V.
Published: July 2018

Currently, stent therapy constitutes to over 95% of all endovascular interventions. The biological and clinical complications of stent therapy can now be well controlled with modern techniques and procedures. However, the mechanical failure of stent remains an important clinical problem [1]. While there is a consensus that such failure usually proceeds through mechanical fracture activation due to fatigue, the mechanisms of fracture activation are not well understood. The virtual analysis of fracture is typically conducted using the Finite Element Method (FEM) model regulated by the externally applied criteria of fracture nucleation. Typically, the FEM model must deal with ambiguity of derivatives of displacement at discontinuities and should contain requirements on mesh size to resolve material damage. In this study, we pursue an alternative approach, called peridynamics, to depict the mechanism of fracture activation. Peridynamic damage model does not require special criteria to guide crack or damage growth and naturally accounts for surface roughness that can highly influence fatigue life of stent.
Design and Development of a Novel Drug Delivery Catheter for Atherosclerosis
Authors: Sarker Sunandita , Chatzizisis Yiannis S. , Kidambi Srivatsan , Terry Benjamin S.
Published: July 2018

Atherosclerosis is a chronic progressive cardiovascular disease that results from plaque formation in the arteries. It is one of the leading causes of death and loss of healthy life in modern world. Atherosclerosis lesions consist of sub-endothelial accumulations of cholesterol and inflammatory cells [1]. However, not all lesions progress to the final stage to cause catastrophic ischemic cardiovascular events [2]. Early identification and treatment of high-risk plaques before they rupture, and precipitate adverse events constitutes a major challenge in cardiology today. Numerous investigations have confirmed that atherosclerosis is an inflammatory disease [3] [4] [5]. This confirmation has opened the treatment of this disease to many novel anti-inflammatory therapeutics. The use of nanoparticle-nanomedicines has gained popularity over recent years. Initially approved as anticancer treatment therapeutics [6], nanomedicine also holds promise for anti-inflammatory treatment, personalized medicine, target-specific treatment, and imaging of atherosclerotic disease [7]. The primary aim of this collaborative work is to develop and validate a novel strategy for catheter-directed local treatment of high-risk plaque using anti-inflammatory nanoparticles. Preselected drugs with the highest anti-inflammatory efficacy will be incorporated into a novel liposome nanocarrier, and delivered in-vivo through a specially designed catheter to high-risk atherosclerotic plaques. The catheter has specially designed perfusion pores that inject drug into the blood stream in such a controlled manner that the streamlines carry the nanoparticles to the stenotic arterial wall. Once the particles make it to the arterial wall, they can be absorbed into the inflamed tissue. In this paper, we discuss the design and development of an atraumatic drug delivery catheter for the administration of lipid nanoparticles.
Tension-Controlled Active Compression Garment for Treatment of Orthostatic Intolerance
Authors: Pettys-Baker Robert , Schleif Nicholas , Lee J. Walter , Utset-Ward Sophia , Berglund Mary Ellen , Dunne Lucy E. , Holschuh Brad , Johnson Christopher , Kelly Kevin , Johnson Bruce , Joyner Michael
Published: July 2018

Medical compression garments are used to treat lymphatic disorders or conditions of poor venous return (e.g. orthostatic intolerance). Conventional compression garments, namely elastic compression sleeves and inflatable compression systems, may aid in relief of these conditions but are also limited in usability. Fixed levels of compression in elastic materials may induce challenges in donning/doffing, complicating patient compliance [1]. Compression levels in inflatable systems are customizable, but these garments are also bulky and require a tethered inflation source [2]. We are interested in developing easy-to-don/-doff compression garments using shape memory alloy (SMA) coil actuators that contract with heat from an applied current which can be wrapped around the body to apply compressive forces. More specifically, we use a spring coil formation as described by Holschuh et al. [3]. Further developed in the Wearable Technology Lab at the University of Minnesota, our current SMA compression garment (SMA-CG) design improves upon the work of Duvall et al. [4] presented in previous year’s (2017) Design of Medical Devices Conference, representing a year’s evolution in active compression garment design that integrate actuators made with SMA.
Miniature Coupled Inductor Coils Enable Remote, Wireless and Secure Product Authentication
Authors: Myers Dean , Davis Michael , Ladwig Peter
Published: July 2018

Device companies commonly install memory chips in a disposable or semi-reusable attachment within a product assembly [1]. Attachment examples include single-use medical diagnostic sensors, reusable monitoring probes, disposable catheters and plug in tools having limited cutting, connection or sterilizing cycles. The memory chip provides information about the attachment to a hosting device that controls or operates the attachment. This stored information may include the attachment’s number of connections or uses, calibration coefficients [2] and the manufacturer or patient identification and date. This attachment data can then be used to enforce product requirements regarding reliability, accuracy, safety and brand [3,4]. For example, the host device can alarm the user, shutdown, or prevent attachment operation when the memory data is outside the product’s validated or tested limits.
Preliminary Design and Testing of a Muscle-Powered Walking Exoskeleton for People With Spinal Cord Injury
Authors: Katti Vikram , Durfee William
Published: July 2018

There are 275,000 people in the US who have spinal cord injury (SCI) and there are about 12,500 new cases each year [1]. Among these 18.5% have incomplete paraplegia and 23% have complete paraplegia [1]. The number of patients experiencing mobility impairment caused by SCI is increasing because of accidents and disease [2,3]. Among people with SCI, 51% identified walking as first choice for a technology application [4].
Cranial Prostheses for Pan-Cortical Neural Interfacing
Authors: Ghanbari Leila , Carter Russell E. , Rynes Matthew , Dominguez Judith , Hu Jay J. , Mossazghi Nahom , Ebner Timothy , Kodandaramaiah Suhasa B.
Published: July 2018

We are engineering neurotechnologies for large-scale cellular resolution activity mapping of the mammalian cortex. We have developed ‘brain windows’ — 3D-printed transparent cranial prostheses for chronic, optical access to the whole cortex. Using compatible imaging methodologies, we have demonstrated the pan-cortical activity map at multiple spatial scales — cellular to the mesoscale.
Realization of a Statically Balanced Compliant Planar Remote Center of Motion Mechanism for Robotic Surgery
Authors: Chandrasekaran Karthik , Somayaji Adarsh , Thondiyath Asokan
Published: July 2018

Robot assisted minimally invasive surgery helps overcome some of the limitations like limited dexterity, fulcrum effect, and lack of 3D vision in manual laparoscopic procedures [1]. A Remote Centre of Motion (RCM) mechanism is an essential part of tele-operated surgical robots. An RCM mechanism enables a rigid surgical tool to maintain a kinematic constraint about the insertion point on a patient’s body [2]. It permits a surgical tool to pivot only about the insertion point and prevents tool translation about the insertion point [3]. A parallelogram architecture based RCM mechanism is one of the most commonly used RCM mechanisms in surgical robots [4] due to its simplicity and large usable range of motion. Commercially available surgical robots such as da Vinci™ from Intuitive Surgical Inc. [5] use synchronous transmission [2] based passive RCM mechanism as a substitute for parallelogram based RCM.
Reduction of the Aortic Aneurysm Sac Pressure Using a Stent With Venturi Structure: A Numerical Study
Authors: Fazel Bakhsheshi Mohammad , Vixege Florian , Grecov Dana
Published: July 2018

Aortic aneurysm is a common disorder which is due to weakening of the aortic wall [1]. Aneurysm rupture is a potentially life threatening complication [2]. The stent graft implantation is one of the potential alternatives for treating patients at high risk for an open surgical procedure. The short-term outcome for stent implantation is promising; however, as with any medical procedure, this has potential limitations such as side branch occlusion, device malfunctions, dilatation at the proximal portion and the so called ‘endoleak’. An endoleak is the persistent blood flow into and within the aneurysmal sac after endovascular repair (i.e. the blood leaks around the endograft which is supposed to have sealed off the entry of blood around it and can be classified into 5 categories[3]). Type I (inadequate seal) and III (graft mechanical failure) endoleaks, characterized by direct communication between systemic and aneurysm sac compartments, pose higher risk of aneurysm rupture and are therefore aggressively treated [4]. Despite advances in the treatment of aneurysm, we believe that there is a still great need for a medical device that can improve patient outcomes.
Development of a Rehabilitation Game for Individuals With Spinal Cord Injury Using a User-Centered Design Process
Authors: Fairhurst Stuart R. , McCool Logan C. , Scheel Kristin M. , Stien Crystal L. , Brenteson Charlotte M. , Hansen Andrew H. , Goldish Gary D. , Voss Gregory O. , Ferguson John E.
Published: July 2018

The use of video games during exercise, exergaming, has been shown to increase energy expenditure without increasing perceived exertion [1]. This suggests that exergaming may be an effective way to engage a patient during rehabilitation and increase adherence to a rehabilitation regime. Existing exergame systems are designed with able bodied users in mind and often combine hand controlled game play while using lower limbs for aerobic exertion, making current systems inaccessible to individuals with spinal cord injuries and others without lower limb function. Our earlier work on increasing exercise accessibility includes developing an ergometer for supine use for patients who have recently had a flap procedure [2]. The goal of the present project was to create an engaging, interactive video game designed for use during arm ergometry by individuals with spinal cord injury (SCI) in either the supine or seated position.
Molecular Analysis of Polymeric Nanocomposites on Prosthesis Design
Authors: Rangel-Vázquez Norma-Aurea , Campos-Cruz Juan-Ramón , Kalla Jonathan
Published: July 2018

There has been an increasing amount of interest in the design and preparation of new biomaterials that can be used in the fabrication of medical devices for artificial prostheses or implant applications. The use of molecular modeling and computational chemistry aids in the design of these materials by calculating different structural properties such as molecular energy, geometry optimization, dipole moments, FTIR, UV-vis, NMR, and others. In this study graphene, polyurethane (PU), polymethylmethacrylate (PMMA) and PU/graphene/PMMA composites have been studied using theoretical calculations. For this work, the AMBER and AM1 simulation methods were used. The results indicate the favorable formation of a cross-linked PU/Graphene composite and adsorption of PMMA.
Design and Verification of a Reloadable Adrenaline Auto-Injector for Intramuscular Injections
Authors: Nair Gokul , Levin Michael , Sivarasu Sudesh
Published: July 2018

Anaphylaxis is a severe allergic reaction when a patient is exposed to an antigen to which they have become hypersensitive. Exposure to these antigens results in the release of mediators from mast cells in the body, causing inflammation of critical organ systems. Without immediate treatment, it can lead to patient mortality within 15 minutes. To increase the probability of patient survival, a dose of adrenaline must be administered. There are several routes of administration, but the use of an Adrenaline Auto Injector is the safest, quickest and most efficient route. An Adrenaline Auto-Injector (AAI) is an injection device that delivers adrenaline to the deep muscle tissue of the body, preferably via the vastus lateralis muscle (as the rate of absorption is more effective than other injection sites such as the deltoid, gluteus maximus etc). Adrenaline Auto-Injectors are preferable to syringes, or prefilled syringes as they are easier to use, and can be used by people that are not medically trained. They can also be used in highly stressful situations without much risk of injury.
An Attempt to Improve Stance Mechanics of Trans-Tibial Amputee Gait by the Design of a Modular Ankle Joint Prosthetic
Authors: During Alastair B. , Sivarasu Sudesh , Vicatos George
Published: July 2018

A-priori research show that trans-tibial (TT) amputees display poor gait parameters when walking with passive mechanical ankle-foot prosthetics (AFP’s). This has large implications for the amputee populations in the developing world, who have limited access to advanced prosthetic technologies and instead rely on baseline AFP’s. Analysis of such baseline AFP’s in literature indicates that the predominant issue with these devices are their inability to adequately replicate the mechanics of a normal ankle during the stance phase of a walking gait cycle. This has shown to be a contributory cause of increased energy expenditure, as well as secondary complications such as osteoarthritis and joint deterioration.

This paper presents the design and analysis of a modular low-cost ankle-joint prosthetic (AJP) that serves as an attachment to existing prosthetic feet, with the intention to improve the ankle mechanics thereof. The AJP is modelled to reproduce ankle joint mechanisms, specifically controlled relative angular flexion in the sagittal plane, using only simple mechanical elements (i.e. compression springs instead of electronics). Initial results were positive, indicating that the AJP improves the stance phase mechanics of the baseline AFP in a simulated TT amputee gait cycle. During forefoot dorsiflexion rollover, an 80%–132% (p < 0.001) increase in joint angle and a 42–56% decrease in ankle stiffness (p < 0.001 for all but one participant) is observed. Following heelstrike a 22%–77% (p < 0.001) increase in joint angle is observed. However equipment and methodology errors left the moment response of this phase unverifiable. The overall conclusion of this paper is that the introduction of the AJP to baseline AFP’s supplies evidence of improved rollover shapes, easier phase transitions, and the facilitation of footflat during mid-stance.
Development and Validation of Numerical Model Simulation for RF Ablation Using the Isolator Synergy Clamp
Authors: Etheridge Michael , Natesan Harishankar , Lopusnik Radek , Cates Adam
Published: July 2018

Thermal ablation is rapidly becoming a standard of care for the treatment of atrial fibrillation (AF), a cardiac disorder characterized by irregular heart rhythm and estimated to impact more than 33 million people worldwide [1]. AtriCure is a company that specializes in epicardial ablation for AF and here we describe the development of a numerical model to study the performance of the Isolator® Synergy™ Clamp bipolar radiofrequency (RF) device. The clamp device features two jaws with embedded electrode pairs, which are used to secure the tissue by clamping across the left atrium (as shown in Figure 1). Energy is applied between the bipolar electrodes at approximately 460 kHz through an impedance-based control algorithm and is additionally duty-cycled between the pairs to further distribute the heating. Patient anatomies vary greatly and measured impedance will depend on atrial wall thickness, epicardial fat, electrode-tissue engagement, and structural variations. Further, tissue conductivity (inversely related to impedance) increases as the tissue is heated, leading to a complicated process, where the heat generation depends on the impedance, which in turn is a strong function of temperature. Energy delivery continues until a phase change in the tissue’s water content occurs, producing a sharp increase in impedance and termination of the ablation. Therefore, since tissue impedance and heating drive the device’s performance, a majority of the effort described here focuses on the validation work done to ensure the model is based on an accurate description of the tissue properties and response. While previous modeling of RF ablation often does include temperature-dependence of tissue properties, the referenced values vary notably and rarely include direct validation of modeling results to benchtop data. Variations in anatomy and fat content can dramatically impact the energy delivery and patient-to-patient treatment efficacy, so an accurate description of the tissue response is critical to understanding the limitations of current energy delivery algorithms and provides an invaluable tool in designing more efficacious ablation devices and algorithms.