bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of an Industrial Area Energy Supply System With Distributed Cogeneration and Solar District Heating
Authors: Buoro Dario , De Nardi Alberto , Pinamonti Piero , Reini Mauro
Published: July 2013

The paper presents the optimization of an energy supply system for an industrial area. The system is mainly composed of a district heating network (DHN), of a solar thermal plant with long term heat storage, of a set of combined heat and power units (CHP) and of additional thermal/cooling energy supply machines. The thermal vector can be produced by solar thermal modules, by fossil-fuel cogenerator or by conventional boilers. The optimization algorithm is based on a Mixed Integer Linear Programming (MILP) model and it has to determine the optimal structure of the energy system and the size of the components (solar field area, heat storage volume, machines sizes, etc.). The model allows to calculate the economical and environmental benefits of the solar thermal plant compared to the cogenerative production, as well as the share of the thermal demand covered by renewable energies. The aim of the paper is to identity the optimal energy production mix able to meet the user energy demands and furthermore how the solar thermal energy integration affects the optimal energy system configuration. The average costs of the heat produced for the users have been evaluated for different optimal configurations, and it emerges that the solution including some cogenerators located in strategic production units, the district heating network, the long term heat storage and a solar plant of proper size, allows achieving the lowest cost of the heat. Thus, the integrated solution turns out to be the best from both the economical and environmental point of view.
Large-Eddy Simulation of the Aerodynamic and Aero-Acoustic Performance of an Industrial Fan Designed for Tunnel Ventilation
Authors: Borello Domenico , Bianchi Stefano , Corsini Alessandro , Rispoli Franco , Sheard Anthony G.
Published: July 2013

The development of industrial fans traditionally relies upon the use of empirical correlations and experimental analyses to validate both aerodynamic and acoustic aspects of fan performance. This paper presents the development of a computational based method focused on the prediction of unsteady aerodynamics and modeling of aero-acoustic sources. The authors applied the study to a single fan from a new range of large tunnel ventilation axial flow fans. The fan specification required mechanical and aerodynamic properties that would enable it to operate in the forward direction under ambient conditions to provide cooling air to the tunnel under routine operation, and in the reverse direction at 400°C under emergency conditions in the event of a tunnel fire. The final aerodynamic and mechanical design was additionally required to generate no more than 80 db during reverse operation, to ensure members of the emergency service could still communicate in the event of a fire. The simulations were carried out using the open source code Open-Foam, within which the authors implemented a (Very) Large Eddy Simulation (V)LES based on an one-equation sub-grid scale SGS model to solve a transport equation for the modeled (sub-grid) turbulent kinetic energy. This improvement of the sub-grid turbulence model is here considered as a remedial strategy in VLES of high-Reynolds industrial flows able to tackle the otherwise insufficient resolution of turbulent spectrum. The VLES of the industrial fan permits to detect the flow features such as three-dimensional separation and secondary flows. Predicted noise emissions, in terms of sound pressure level spectra, are compared with experimental results, and found to agree within the uncertainty of the measurements.
Integrated Approach to Gas Turbine Rotor Condition Assessment and Life Management
Authors: Swaminathan V. P. (Swami) , Dean Gil J. , Scheibel John R.
Published: July 2013

Turbine manufacturers place limits on the service life of gas turbine (GT) rotors/discs based on either the number of hours of operation or the number of start-stop cycles. A significant number of gas turbine rotors are either condemned or slated for replacement during a future outage. Some turbines experience premature cracking which results in the replacement of select rotor components. Examples of such cases are GE Frame 7EA compressor disc cracking, Frame 7FA/9FA turbine disc air-feed slot and post cracking, and Frame 6001B turbine disc rabbet cracking Many Alstom 11N and Siemens W-501 rotors and discs are also replaced based on design life limitations. This experience prompted EPRI, sponsored by gas turbine owners to conduct projects in this area. Under this program, TurboMet International and AccTTech,LLC conducted metallurgical evaluation of cracked discs to understand the crack initiation and propagation mechanisms, detailed structural engineering analysis to understand the root cause of cracking and developed solutions; and to provide recommendations to turbine owners to mitigate such failures. Condition and remaining life analysis of several turbine models was conducted using rigorous engineering analysis to provide objective technical recommendations to turbine users to safely extend the life of the rotors. This collective experience has result in guidelines for safe reinspection intervals to mitigate future risk. In order to obtain pertinent material properties needed for such detailed engineering analysis, retired rotors and discs were obtained from both compressor and turbine sections. Nondestructive examinations (NDE) and materials testing were conducted to assess component condition and mechanical properties such as tensile, fracture toughness, crack growth, creep, low-cycle fatigue, etc. This paper provides an overview of an integrated rotor condition and life assessment approach including several examples of component evaluations.
Prediction of Certification Noise Levels Generated by Contra-Rotating Open Rotor Engines
Authors: Kritikos Kosmas , Giordano Emidio , Kalfas Anestis I. , Tantot Nicolas
Published: July 2013

The tendency for environmentally friendlier aeronautic engines, led to the re-examination of the contra rotating open rotor (CROR) as a more efficient and less polluting propulsion system, thanks to its noticeably high propulsive efficiency. The geometrical and operational characteristics of these contra rotating propellers are examined in order to optimize the noise emissions, given the challenging regulation context for such an unducted concept. For this research, computational techniques have been used to develop a numerical model for prediction of noise levels generated by CRORs propellers. An extended database of unsteady CFD simulations, generated with innovative methods, namely a non-linear harmonic flow solver and an acoustic propagation model based on the Ffowcs Williams–Hawkings approach, have been used to assess the noise spectra measured in the certification points. Sound pressure levels and frequencies have been afterwards converted into EPN levels along the aircraft flight path, according to the ICAO regulation. The whole procedure has been applied to 102 different cases to establish the influence of several independent parameters on noise emissions. A surface response model has finally been developed, providing an easy tool of fast utilization to be implemented in optimization platforms.
Behavior of Secondary Flow in a Low Solidity Tandem Cascade Diffuser
Authors: Sakaguchi Daisaku , Ueki Hironobu , Ishida Masahiro , Hayami Hiroshi
Published: July 2013

Low solidity circular cascade diffuser abbreviated by LSD was proposed by Senoo et al. showing a high blade loading or a high lift coefficient without stall even under small flow rate conditions. These high performances were achieved by that the flow separation on the suction surface of the LSD blade was successfully suppressed by the secondary flow formed along the side walls. The higher performance of the LSD was achieved in both pressure recovery and operating range by adopting the tandem cascade because the front blade of the tandem cascade was designed suitably for small flow rates while the rear blade of the tandem cascade was designed suitably for large flow rates.

In order to clarify the reason why the tandem cascade could achieve a high pressure recovery in a wide range of flow rate, the flow in the LSD with the tandem cascade is analyzed numerically in the present study by using the commercial CFD code of ANSYS-CFX 13.0. The behavior of the secondary flow is compared between the cases with the single cascade and the tandem one. It is found that the high blade loading of the front blade is achieved at the small flow rate by formation of the favorable secondary flow which suppresses the flow separation on suction surface of the front blade, and the flow separation on pressure surface of the front blade appeared at the design flow rate can be suppressed by the accelerated flow in the gap between the trailing edge of the front blade and the leading edge of the rear blade, resulting in the positive lift coefficient in spite of a large negative angle of attack.
Preliminary Design of a Low-Cost Mobile Test Cell for Small Gas Turbine Engines
Authors: Pečinka J. , Jílek A.
Published: July 2013

This paper describes the design considerations and calculations of a mobile low-cost test cell for small gas turbine engines (GTE). The test bed was designed for the TS-20 jet engine, originated in a gas turbine starter and should be used mostly for educational purposes and for experimental validation of analytical computations. Limitations of the project were the engine air mass flow rate, low noise emissions for possibility of performance close to urban area, low cost and good mobility of the test cell. The design of the test cell structure, inlet and exhaust silencers from the aero-thermodynamic and sound suppression point of view is presented. The calculation results and respective design solutions are offered.
The Influence of Humidity on the Creep Life of a High Pressure Gas Turbine Blade: Part I—Heat Transfer Model
Authors: Eshati S. , Laskaridis P. , Haslam A. , Pilidis P.
Published: July 2013

The cooling of high temperature gas turbines has been the subject of intensive work over the past few decades. Analysis of the metal temperature of cooled blades requires the solution of the equations governing the heat flow through the blade given the internal and external distributions of the boundary gas temperatures and heat transfer coefficients. An analytical model to investigate the influence of Water Air Ratio (WAR) on turbine blade heat transfer and cooling processes (and thus the blade creep life) of industrial gas turbines is presented. The method is based on a blade with convective cooling and a thermal barrier coating (TBC). The approach is based on engine performance, heat transfer models (hot side and cold side model), in addition to a method that accounts for the changes in thermal conductivity, viscosity, density and the gas properties of moist air as a function of WAR. The evaluation of heat transfer data in this model is considered by using non-dimensional parameters namely: Reynolds number, Nusselt number, Stanton number, Prandtl number and other related parameters. The aim of this paper is to present an analytical model to investigate the influence of humidity on the turbine blade heat transfer and cooling processes which, in turn, affect blade creep life. The developed model can be used to assess the main parameters that influence blade cooling performance, such as cooling methods, alternative cooling fluids, blade geometry, gas properties and material and thermal barrier coatings. For a given off-design point, the WAR was varied from dry to humid air (air/water vapour mixtures). The whole cooled blade row is regarded as a heat exchanger with the presence of TBC subjected to a mainstream hot gas flow from the combustion chamber.
The Influence of Humidity on the Creep Life of a High Pressure Gas Turbine Blade: Part II—Case Study
Authors: Eshati S. , Laskaridis P. , Haslam A. , Pilidis P.
Published: July 2013

The determination of the rate of heat transfer from the turbine blade in a cross flow is important in hot section gas turbine life assessment. For design purposes, the rate of heat transfer is normally fixed by semi-empirical correlations. These correlations require knowledge of fluid properties which depend on temperature. For gases these properties are normally available only for the dry state, thus the possible effect of the water vapour content has been overlooked. Many gas turbines operate in environments in which air humidity is very low and therefore has little influence on gas turbine performance. However humidity becomes more important in hot, humid climates where there are large variations in ambient absolute humidity, especially in hot and humid climates. The aim of this paper is to investigate and present the effect of humidity at different operating conditions on the turbine blade coolant heat transfer and blade creep life. The effect of humidity was considered only on the air coolant side. he The heat transfer coefficient on the hot side was calculated for dry hot gas. This avoided the balancing effect of each other (heat transfer coefficient coolant side and hot side). The WAR at each operating point is quantified based on the ambient temperature and the relative humidity (0%–100%). Results showed that with increasing WAR the blade inlet coolant temperature reduced along the blade span. The blade metal temperature at each section was reduced as WAR increased, which in turn increased the blade creep life. The increase in WAR increased the specific heat of the coolant and increased the heat transfer capacity of the coolant air flow. Different operating points were also evaluated at different WAR and Tamb to identify the effect of WAR on the creep life. The results showed that an increase in WAR increased the blade creep life. The creep life of the blade at each section of interest was obtained as a function of the blade section stress and the blade metal section temperature using the LMP approach.
Demonstration of Simultaneous Temperature and Power Control in a Simulation Facility for a SOFC Hybrid System
Authors: Caratozzolo Francesco , Ferrari Mario L. , Traverso Alberto , Massardo Aristide F.
Published: July 2013

This study is based on a complete hybrid system emulator test rig developed at the University of Genoa (Savona laboratory) by the Thermochemical Power Group (TPG). The plant is mainly composed of a 100 kW recuperated micro gas turbine coupled with both anodic and cathodic vessels for high temperature fuel cell emulation. The test rig was recently equipped with a real-time model for emulating components not physically present in the laboratory (SOFC block, reformer, anodic circuit, off-gas burner, cathodic blower). This model is used to fully evaluate thermodynamic and electrochemical performance related to solid oxide fuel cell systems. Using a UDP based connection with the test rig control and acquisition software, it generates a real-time hardware-in-the-loop (HIL) facility for hybrid system emulation. Temperature, pressure and air mass flow rate at the recuperator outlet (downstream of the compressor) and rotational speed of the machine are inputs from the plant to the model. The turbine outlet temperature (TOT) calculated by the model is fed into the machine control system and the turbine electric load is moved to match the model TOT values.

In this study various tests were carried out to characterize the interaction between the experimental plant and the real-time model; double step and double ramp tests of current and fuel provided the dynamic response of the system.

The control system proved to be fast, compared to the slow thermal response of the SOFC stack, and also reliable. The hybrid systems operated at 90% of nominal power with electrical efficiency of about 56% based on natural gas LHV.
A Method to Evaluate the Emissions of Gas Turbine for Power Generation
Authors: Mohamed W. , Sethi V. , Pilidis P. , Pervier Hugo , Khan Raja S. R.
Published: July 2013

This paper focuses on emission prediction for plants which use gas turbines for electrical power generation. A Techno-Economic, Environmental and Risk Analysis (TERA) framework, developed at Cranfield University, is used as the modelling philosophy. Thermodynamic performance simulation is at the core of the study whilst the risk, lifing, economics and environmental modules are built around the performance. Recently, the public agenda has emphasised environmental issues and new restrictive legislation on emissions can be expected. It means electrical power generation companies will have to look for ways to reduce their emissions. The replacement of out-dated and/or obsolete machinery having lower overall energy efficiency is one way. However, selection of new machinery will not only require economic and technical risk assessment but also its environmental impact. In-house software (Turbomatch) is used to calculate thermodynamic performance and an adaptable aviation emissions model, to fit industrial applications is presented here with the emissions model focusing on NOx, CO2, H2O, CO and unburned hydrocarbons. Then, the environmental module has been fed by the levels of NOx, CO2 and H2O to estimate the damage the engine will cause to the environment over several years with respect to global warming. Based on both field and public domain data two hypothetical engine configurations are investigated. One of them, a 165MW single shaft industrial machine, is used as the baseline to compare against the second one which is a 30MW aeroderivative single shaft machine.

The results predict that the 165MW single shaft engine model is more sensitive to an increase in ambient temperature than the 30MW aeroderivative single shaft engine model. The larger engine thermal efficiency reduces by 4%, for 30°C increase in ambient temperature above design point. That of the smaller engine model decreases by 2 1/2%. The loss in shaft power is also sharper for the 165MW engine model; however the significantly greater stability shown for the 30MW engine with respect to ambient temperature variation comes at a price. This engine emits higher levels of all pollutants, especially NOx, compared to the 165MW engine due to relatively higher firing temperature in relation to the engine size. This paper helps to establish the basis of a methodology to analyse GT emissions for power generation. The other aim is to integrate these findings into a system which will act as optimiser for TERA analysis. The effectiveness of the system is that it will allow designers and users to compare between alternative possibilities for turbomachinery selection and replacement. There are other models being developed at Cranfield University which combine systems to give an overall evaluation in terms of technical, economic, environmental and risk perspectives for power generation [1].
Development of Test Procedure for Quantifying the Effects of Salt and Water on Gas Turbine Inlet Filtration
Authors: Wilcox Melissa , Poerner Nathan , Kurz Rainer , Brun Klaus
Published: July 2013

Inlet filtration on a gas turbine strongly influences the performance degradation and life of the turbine. The inlet filtration system must have a diverse set of stages to remove the contaminants present in various phases (gas, liquid, and solid). Filters for gas turbine filtration systems are currently classified using one of three standards: ASHRAE 52.2, EN 779, or EN 1822. These standards measure the performance of filters in the dry state and do not consider the performance of the filter when wet (saturated with water). Many locations where gas turbines operate, experience conditions where the filter can be dampened or saturated which can significantly influence the filter’s performance. In addition, if soluble particles, such as sodium chloride, are captured by the filter, then there is a potential for the soluble particles to be carried by the water through the filter and into the gas turbine. In order to understand the performance of a filter with water present, a procedure is being developed. This procedure intends to quantify the effects of water and salt on the performance of filters. The procedure has been written, and a series of preliminary validation tests have been completed. The results of the preliminary validation testing show that a change can be observed in the filter’s performance when salt and water are introduced into the flow stream. In addition, the preliminary validation testing revealed many areas where the test procedure could be improved.
A Parametric Study of Reversible Jet-Fan Blades’ Aero-Mechanical Performance
Authors: Daneshkhah Kasra , Sheard Geoff
Published: July 2013

This paper presents a parametric design of fully reversible jet-fan blades for ventilation and smoke control use in road tunnels. The blade design variables are tip solidity, twist and camber distribution. The authors base the design methodology on a sensitivity analysis which they obtained from a response surface approximation. They construct the latter using high-fidelity computational analysis tools for four experimental cases which they generated using an experimental design approach. The sensitivity analysis calculates a rank and a weight for each design variable that affects the jet-fan performance parameters thrust and efficiency, and thus facilitates insight into each design’s relative performance. Finally, the authors present a redesign of an existing reversible jet-fan blade by following the design guidelines obtained from the sensitivity analysis. The authors study and discuss the aerodynamic and structural characteristics of the redesigned blade and compared it to that of the baseline design configuration.
Numerical Tools for High Performance Axial Compressor Design for Teaching Purpose
Authors: Tomita Jesuíno Takachi , Barbosa João Roberto
Published: July 2013

The preliminary design tools, for the design and performance analysis of axial flow compressors, has been developed based on reduced-order throughflow model. The in-house numerical tools developed specially for turbomachinery preliminary sizing and calculation of its operational characteristics is being an interesting experience in both under- and graduate lectures. Appropriate loss correlations have been selected aiming at good geometrical initial sizing. Flow properties distribution has been obtained using meanline code combined with a quasi-3D streamline curvature code. Any number of sections from hub to tip of each blade can be used for the determination of the blade shape. The compressor operation map calculated is validated against published test data. Details of the developed methodology and implementation are discussed.
Analysis of IGFC With Exergy Recuperation and Carbon Dioxide Separation Unit
Authors: Kawabata Masako , Kurata Osamu , Iki Norihiko , Fushimi Chihiro , Tsutsumi Atsushi
Published: July 2013

Integrated Coal Gasification Fuel Cell Combined Cycle (IGFC) is expected to be the most efficient power generation system in coal fired power generation systems [1,2]. However, more energy efficient power generation system has to be developed to decrease CO2 emission in the middle and long term. Thus, the authors have proposed Advanced Integrated Coal Gasification Combined Cycle (A-IGCC) and Advanced IGFC (A-IGFC) systems, which utilize exhaust heat from solid oxide fuel cells (SOFC) and / or a gas turbine as a heat source of gasification (exergy recuperation) [3]. Previously A-IGCC [4] and A-IGFC [5] without CO2 capture option were analyzed with the process simulator HYSYS®.Plant (Aspen technology Inc.) to calculate thermal efficiencies of the proposed systems. Then IGCC and A-IGCC with CO2 capture option [6, 7] were analyzed with Amine process simulator AMSIM(DBR), a module in PRO/II® (Invensys Process Systems Japan, Inc) combined with HYSYS®.Plant model. It shows in the results of thermal efficiency with CO2 capture option that the penalty of A-IGCC case is larger than that of IGCC case, indicating somewhat scope for increase of exergy recuperation in A-IGCC case [6]. This study deals in the analyses of A-IGFC with CO2 separation unit.
System Matched 3D Radial Impeller Design With Variable Inlet Angle Distributions
Authors: Semel Matthias , Smith Henrik , Epple Philipp , Litfin Oliver , Delgado Antonio , Pfannschmidt Klaus , Grobeis Detlev
Published: July 2013

In vacuum cleaners radial impellers with high rotational speed are very often used. A high rotational speed is connected with a best efficiency point of the radial impeller at a high flow rate. This is contrary to the working point of the whole system. Thus there is need for a radial impeller designs having a high efficiency at low flow rates under the restriction of a high rotational speed. One important parameter connected to the hydraulic efficiency characteristics of the radial impeller is the blade inflow angle β1. In order to shift the best efficiency point towards lower flow rates radial impellers with double curved blades and a linear β1 distribution were designed and CFD simulations were done in order to investigate the effect of this approach. A linear variation of the inflow angle β1 enables the designer to shift the efficiency characteristics of the impeller towards lower flow rates with a gain in hydraulic efficiency and pressure increase.
Micro-Turbine Design Point Definition Using Genetic Algorithm With Single and Multi-Objective Optimization
Authors: Cavalca Diogo F. , Bringhenti Cleverson
Published: July 2013

During a gas turbine development phase an important engineer task is to find the appropriate engine design point that meet the required specifications. This task can be very arduous because all possible operating points in the gas turbine operational envelope need to be analyzed, for the sake of verification of whether or not the established performance might be achieved. In order to support engineers to best define the engine design point that meet required performance a methodology was developed in this work. To accomplish that a computer program was written in Matlab®. In this program was incorporated the thermoeconomic and thermodynamic optimization. The thermodynamic calculation process was done based in enthalpy and entropy function and then validated using a commercial program. The methodology uses genetic algorithm with single and multi-objective optimization. The micro gas turbine cycle chosen to study was the recuperated. The cycle efficiency, total cost and specific work were chosen as objective functions, while the pressure ratio, compressor and turbine polytropic efficiencies, turbine inlet temperature and heat exchange effectiveness were chosen as decision variables. For total cost were considered the fixed costs (equipment, installation, taxes, etc.) and variable costs (fuel, environmental and O&M). For emissions were taken into account the NOx, CO and UHC. An economic analysis was done for a recuperated cycle showing the costs behavior for different optimized design points. The optimization process was made for: single-objective, where each objective was optimized separately; two-objectives, where they were optimized in pairs; three-objectives, where it was optimized in trio. After, the results were compared each other showing the possible design points.
Component-Based Approach to Maintenance Modeling of Gas Turbines
Authors: Volovoi Vitali , Valenzuela René , Bhatnagar Himanshu , Nordlund Scott , Davis Fred , Villeneuve Frederic , Guo Yan , Patel Chirag
Published: July 2013

Power plants are complex systems consisting of thousands of heterogeneous components. The maintenance policy of such systems includes grouping the maintenance actions of different components. This grouping of the maintenance actions together with functional interactions between the components results in system level models that are highly coupled. Accurate models of the maintenance process would allow plant managers and system designers to generate cost-effective maintenance policies. A system level model with explicit accounting of all components, interactions and maintenance policy groupings would provide the desired accuracy, but the creation of such a model is infeasible or very expensive. In this paper, a bottom-up modeling procedure that allows for the creation of the maintenance model is introduced. This approach reduces the complexity of the modeling process while still capturing all the relevant characteristics. Each component type present in the system is modeled separately, but each model includes an aggregated representation of the effects of the rest of the system on the modeled component type. This procedure applied to both a midsize-system and to a gas turbine engine. Simulations are used to illustrate how the created models are used and to verify the level of accuracy by comparing the results to system-level models.
Design of a Stirling Machine in a Multi-Cylinder Configuration for Microcogeneration
Authors: Chatterton S. , Pennacchi P. , Vania A. , Ricci R. , Ghisoni A.
Published: July 2013

At present, the attention of the market in Stirling engines is increasing for small size applications of electrical power generation. These engines are based on a simple principle of functioning and could employ renewable energy sources. Two main configurations are available on the market: the first is a four-cylinder engine with wobble yoke mechanism and the second is represented by the single-cylinder free-piston concept. The paper is aimed at investigating several multi-cylinder configurations for the improvement of the engine performances. These are evaluated by means of numerical simulations taking into account the dynamics of the mechanism and the thermal aspects of the cycle. In particular the attention of the authors is focused on the design of a new configuration with a higher number of cylinders.
Forward Blade Sweep Applied to Low-Speed Axial Fan Rotors of Controlled Vortex Design: An Overview
Authors: Vad János
Published: July 2013

An overview is given on the research maintained by the author about design aspects of three-dimensional blade passage flow in low-speed axial flow industrial fan rotors, affected by spanwise changing design blade circulation due to controlled vortex design (CVD), blade forward sweep (FSW), and their combination.

It was pointed out that, comparing the CVD method to free vortex design, the fluid in the blade suction side boundary layer has increased inclination to migrate radially outward, increasing near-tip blockage and loss. It was concluded that the benefit of FSW, in terms of moderating loss near the tip, can be better utilized for rotors of CVD, in comparison to free vortex design.

Compared to free vortex design, FSW applied to blades of CVD was found especially beneficial in loss reduction also away from the endwalls, via shortening the flow paths on the suction side — being anyway elongated by the radially outward flow due to CVD —, and thus, reducing the effect of wall skin friction. The necessity of correcting the swept blades was pointed out for matching with the prescribed CVD circulation distribution.
Closed Joint Traumatic Impaction and Its Influence on Meniscal Cell Viability
Authors: Killian Megan L. , Haut Roger C. , Haut Donahue Tammy L.
Published: July 2013

Traumatic impaction is known to cause acute cell death and macroscopic damage to cartilage and menisci in vitro1,2,3. It is understood that damage to the menisci can lead to chronic problems associated with excessive cartilage wear and the eventual onset of osteoarthritis (OA)4. Additionally, cartilage fissuring, subchondral bone bruising, and chondrocyte death are also believed to lead to the rapid progression of joint degeneration5. Such injuries, along with posterolateral meniscal tearing, are often observed after traumatic impaction and anterior cruciate ligament (ACL) rupture6–9. Therefore, understanding how the menisci and cartilage respond acutely to impaction may help guide future therapies following traumatic knee injury in order to prevent the development of OA.
Appropriate Technology in an Introductory Engineering Design Experience
Authors: Eberhardt Alan W. , Lesley Richard J. , Oliver Tina G. , Scripa Rosalia N.
Published: July 2013

EGR 200, Introduction to Engineering Design, provides transfer students at the University of Alabama at Birmingham an introductory engineering experience, including a 5-week design project. This year, the authors led a project that involved the design of crutches for use in a developing nation that featured the use of “appropriate technology” regarding materials and construction techniques. The target country was Zambia, Africa, which is one of the poorest countries in the world. In Zambia, the majority of the population lives on less than $2 USD per day [1]. Lack of medical facilities and doctors leads to many serious health issues. Infection often leads to amputation, creating a need for low cost crutches.
A Measurement Tool to Assess Hand Kinematics and Kinetics in Piano Players
Authors: Patterson Rita M. , Kondraske George , Yoshimura Eri , Kumar Shrawan , Chesky Kris
Published: July 2013

The purpose of this study was to design and develop a measurement tool and protocol to measure hand posture and finger loads during piano playing and to study the relationship between palmar arch and associated forces generated when pressing keys during piano playing. Information gained from developing a system to study these parameters will ultimately provide piano players and instructors with information to enhance playing performance as well as strategies to reduce hand injuries and playing related pain.
The Effect of Different Material Combinations on Wear of an Artificial Cervical Disc as Standalone vs. Placed in a Ligamentous Motion Segment
Authors: Bhattacharya S. , Goel V. K. , Kiapour A. , Liu X.
Published: July 2013

Earlier efforts in areas of hip and knee arthroplasties suggest that wear debris, especially from polymeric components, could initiate inflammatory responses leading to peri-prosthetic osteolysis and bone resorption at the implant-bone interface. Aseptic loosening of implants due to particle induced osteolysis is the primary cause of revision surgeries. Metal based implants are considered superior in terms of wear resistance.1–2 However metal-on-metal articulation leads to much smaller sized particulates in comparison to metal-on-polymers. Thus for an equal volume of wear debris from both polymer and metal, the number of metallic particulates can be up to 100 times greater3. Accumulation of metallic debris in the periprosthetic tissue leads to the formation of a fibrous membrane, which might act as a channel for polymeric particulates4. Bench top wear tests as well as bioreactivity studies have emerged as a powerful preclinical tool. However there is still a gap between the in vitro bench-top wear tests and the retrieval test cases. Additionally, these experiments are time consuming, expensive, and labor-intensive procedures. In spite of the fact that experimental data are indispensable, alternatives need to be explored. Predictive finite element modeling based on wear-laws serve as an excellent design tool for parametric analyses. In such models, the effect of individual variables can be judged independently leading to an understanding of the role of that parameter on the final outcome.
A Hybrid Particle-Cell Model for Nanoparticle Targeted Delivery in Microcirculation
Authors: Liu Yaling , Tan Jifu , Thomas Antony
Published: July 2013

Multifunctional nanomedicine holds considerable promise as the next generation of medicine that allows for targeted therapy with minimal toxicity. Most current theoretical studies considered nanoparticle (NP) suspensions in a Newtonian fluid without blood cells [1–3]. However, blood is a complex biological fluid composed of deformable cells, proteins, platelets, and plasma. For blood flow in capillary, arterioles and venules, the particulate nature of the blood need to be considered in the delivery process. Non-Newtonian effects such as the cell-free-layer and nanoparticle-cell interaction will largely influence both the dispersion and binding rates, thus impact targeted delivery efficacy. In this paper, a particle-cell hybrid model is developed to model NP transport, dispersion, and adhesion dynamics in blood suspension. The motion and deformation of red blood cell is captured through Immersed Finite Element method. The motions and adhesion of individual NPs are tracked through Brownian adhesion dynamics. A mapping and interaction potential function is introduced to consider the cell-particle collision. NP dispersion and binding coefficients are derived from the developed model under various rheology conditions. The influence of vascular flow rate, diameter, and particle size on NP distribution and delivery efficacy is characterized.
A Strategy to Develop a Finite Element Model to Represent Backflow During Infusions Into Brain Tissue
Authors: Molano Ana Belly , García José Jaime , Smith Joshua H.
Published: July 2013

Convection-enhanced delivery is a means to deliver therapeutic agents directly into brain tissue for the treatment of brain tumors and other disorders of the central nervous system. Unfortunately, recent clinical trials have demonstrated limited efficacy of this procedure and suggested that one of the main obstacles is poor distribution of the infused agent [1].
Pathway to Finite Element Analysis of Stress Urinary Incontinence Mechanics
Authors: Spirka Thomas , Kenton Kimberly , Brubaker Linda , Damaser Margot
Published: July 2013

Stress urinary incontinence (SUI), a condition that affects mainly women, is characterized by the involuntary leakage of urine caused by an increase in abdominal pressure in the absence of a bladder contraction that raises the vesical (bladder) pressure to a level that exceeds the urethral closure pressure.
Both Hypoglycemia and Hyperglycemia Prevent Endothelial Cell Actin Fiber Alignment to Fluid Shear Stress
Authors: Kemeny Steven F. , Morss Clyne Alisa
Published: July 2013

Diabetic patients are unable to effectively regulate blood glucose, which leads to periods of both hypo- and hyperglycemia [1]. High glucose increases reactive oxygen species formation [2], permeability [3], apoptosis [4], and basement membrane protein production [5] in endothelial cells. Recently hypoglycemia has been proposed to increase reactive species and apoptosis [6] and upregulate VEGF [7].
A Simulation Study to Investigate Ankle Sprain Mechanisms
Authors: Wei Feng , Fong Daniel Tik-Pui , Haut Roger C.
Published: July 2013

Ankle sprain is the most common injury in sports [2], but the mechanism of injury may not always be clear. Sports-related injury mechanisms can be studied through various approaches: cadaveric experiments, kinematics, biomechanics, and computational modeling. The advantage of computer simulation is the ability to separate motions and study them individually.
A Theoretical Assessment of the Influence of Myosin Filament Dispersion on Smooth Muscle Contraction
Authors: Kroon Martin
Published: July 2013

A new constitutive model for the biomechanical behavior of smooth muscle tissue is employed to investigate the influence of statistical dispersion in the orientation of myosin filaments. The number of activated cross-bridges between the actin and myosin filaments governs the contractile force generated by the muscle and also the contraction speed. A strain-energy function is used to describe the mechanical behavior of the smooth muscle tissue. The predictions from the constitutive model are compared to histological and isometric tensile test results for smooth muscle tissue from swine carotid artery. In order to be able to predict the active stress at different muscle lengths, a filament dispersion significantly larger than the one observed experimentally was required. Furthermore, a comparison of the predicted active stress for a case of uniaxially oriented myosin filaments and a case of filaments with a dispersion based on the experimental histological data shows that the difference in generated stress is noticeable but limited. Thus, the results suggest that myosin filament dispersion alone cannot explain the increase in active muscle stress with increasing muscle stretch.
Assessment of Minimally Invasive Device That Provides Simultaneous Adjustable Cardiac Support and Active Synchronous Assist in an Acute Heart Failure Model
Authors: Moreno Michael , Biswas Saurabh , Harrison Lewis D. , Pernelle Guillaume , Miller Matthew W. , Fossum Theresa W. , Nelson David A. , Criscione John C.
Published: July 2013

Congestive heart failure (CHF) is a debilitating disease that is generally initiated by some index cardiac event and ultimately characterized by left ventricular (LV) remodeling which dramatically alters the mechanical environment about the heart. It is well established that mechanical stimuli (e.g., stress or strain) are important epigenetic factors in cardiovascular development, adaptation, and disease.1–3 Interestingly, abnormal cardiac kinematics is often considered a symptom of heart failure when in actuality it is likely a primary contributing factor to the relentless progression of the disease.4 Cellular responses to pathologic mechanical factors lead to further pathologic remodeling and a positive feedback loop emerges such that eventually a threshold is reached wherein the neurohormal compensatory mechanisms activated to maintain homeostasis following the initial cardiac event are no longer sufficient to deter further progression of the disease. Consequently, treatment strategies that fail to remedy the aberrant mechanical environment become increasingly ineffective as the disease progresses.
A Biomechanical Model for the Biaxial Effect of the Contraction of Muscle Cells
Authors: Agianniotis Aristotelis , Rachev Alexander , Stergiopulos Nikos
Published: July 2013

The arterial tissue consists of elastin and collagen which develop passive stresses in the arterial wall, and muscle cells that develop active stresses when are appropriately stimulated. Earlier model for the active properties of the arterial wall, where the muscle cells orientation is assumed circumferential, failed in describing accurately the tissue response to inflation-extension loading. It has been hypothesized that the development of active stresses in both circumferential and longitudinal directions could overcome this shortcoming.

Inflation-extension tests on common carotids of rabbits were performed with the muscle cells being either fully relaxed or fully contracted. Biomechanical model for the active properties of the arterial wall was developed, accounting for angular orientation of the muscle cells on the circumferential-longitudinal plane.

The biaxial constricting effect of the muscle cells was shown to characterize more accurately the active properties of the arterial wall compared to the model with only circumferential contribution.
Assessment of Pressure Oscillations Delivery to the Lung
Authors: Al-Jumaily A. M. , Reddy P. , Mussa J.
Published: July 2013

Pressure wave oscillations are used in the treatment of several respiratory ailments such respiratory distress syndrome. A theoretical model and experimental approach are used to quantify the level of delivery of air pressure oscillations applied at the mouth to various parts of the lung. Both approaches indicate that these oscillations can be delivered with specific frequencies and magnitudes deep in the lung and under specific operating conditions.
A Predictive Method for Human Carotid Plaque Rupture Using In Vivo Serial MRI With Follow-Up Scan Showing Actual Rupture and MRI-Based 3D Models With Fluid-Structure Interactions
Authors: Wu Zheyang , Yang Chun , Tang Dalin
Published: July 2013

It has been hypothesized that mechanical risk factors may be used to predict future atherosclerotic plaque rupture. Much progress has been made in computational modeling, medical imaging, and mechanical analysis for atherosclerotic plaque vulnerability assessment in recent years [1–2]. However, truly predictive methods to predict plaque rupture are currently lacking in the literature and practice. In this paper, we introduce a procedure using computational and statistical models based on serial magnetic resonance imaging (MRI) to quantify sensitivity and specificity of mechanical predictors and their combinations to identify the best candidate for rupture prediction. Serial MRI of carotid plaque from a patient with follow-up scan showing ulceration (rupture) was acquired and the actual appearance of ulceration was used as “gold standard” and validation for the predictive method.
Analysis of the Intervertebral Disc’s Mechanical Behavior Under Impact Loading Conditions
Authors: Jamison David , Cannella Marco , Pierce Eric C. , Martin Shawn K. , Marcolongo Michele A.
Published: July 2013

In the U.S. Navy, high speed boat (HSB) crewman frequently suffer from lower back pain and accelerated intervertebral disc (IVD) degeneration. It is believed that this stems primarily from the large vertical accelerations and forces experienced while navigating on the open seas as the boats pitch and crash into the water. In a study of self-reported injuries for HSB operators, 33.6% of these subjects had suffered a lower back injury while on duty3. This is high when compared with the 15 to 20% of adults in the general population who experience low back pain.
Analysis of Infarct Size on Myocardial Infarction Remodeling
Authors: Zhang Pei , Li Tieluo , Williams Katrina , Li Shuyin , Wei Xufeng , Son Hosung , Sanchez Pablo , Griffith Bartley P. , Wu Zhongjun J.
Published: July 2013

In the United States, over one million patients sustain left ventricular (LV) injury after myocardial infarction (MI). LV remodeling is an adaptive process of hypertrophy that includes infarct expansion, reduced contractility and LV dilation. Progressive enlargement of non-ischemic, hypocontractile myocardium in the adjacent zone (AZ) following the transmural MI has been identified clinically, which contributes to the development post-MI cardiomyopathy in patients. Till now, how the early regional biomechanical and cellular changes, particularly in the AZ, relate to LV remodeling process remains incompletely understood. This study aims to investigate the temporal and/or spatial variations of strain/stress and myocyte size in an ovine model with various MI sizes.
Finite Element Comparison of Cranial Sinus Function in the Dinosaur Majungasaurus and Head-Clubbing Giraffes
Authors: Snively Eric , Cotton John R. , Witmer Lawrence , Ridgely Ryan , Theodor Jessica
Published: July 2013

Majungasaurus crenatissimus is a spectacularly preserved carnivorous dinosaur from latest Cretaceous Madagascar. Computed tomographic (CT) scans reveal unusual internal anatomy of the dinosaur’s cranium [1,2; Figure 1]: the nasals form a large hollow chamber traversed with bony struts, and a unicorn-like projection of the frontals is also hollow. The wall thickness and struts within these sinuses recall sinuses of giraffes, which strike each other with a median projection (ossicone) above a frontal sinus and lateral ossicones of the parietals [3]. Giraffe-like cranial sinuses, and large attachments for neck muscles [4], raise the hypothesis that Majungasaurus could engage in giraffe-like head strikes to each other’s necks and flanks.