bluuebunny/crossref_metadata_2025 huggingface dataset:
Classification of Blood Flow in Cerebral Aneurysm Considering the Parent Artery Curves
Authors: Nakayama Toshio , Sugiyama Shin-ichiro , Ohta Makoto
Published: April 2014

Background and purpose: Recently, the number of endovascular treatments has increased worldwide because of advances in minimally invasive surgery. We considered the effect of reduced flow due to stent implantation and proposed the design of stent strut pattern from the viewpoint of fluid dynamics. We developed an optimized stent strut pattern using a computational fluid dynamics (CFD) system. A classification of cerebral aneurysms was proposed using the aspect ratio (AR) and the stent strut pattern was optimized. The results of optimal stent strut pattern for reduced blood flow speed and wall shear stress were different, and the influence of the AR values was small because there was no dependence on relationship between blood flow and the AR values due to the use of a straight pipe in the parent artery. The classification of blood flow pattern in a cerebral aneurysm must consider the parent artery curves. In this study, we investigated the relationship between the blood flow pattern in cerebral aneurysms and parent artery curves using CFD.

Methods: To investigate the influence of blood flow based on the parent artery curve, the parent artery shape was constructed as follows. Patient-specific parent artery shape with a cerebral aneurysm was reconstructed using OsiriX. Center line was extracted using a vascular modeling tool kit. The parent artery shape was reconstructed based on this center line using CAD. The diameter of the parent artery was 4 mm. The cerebral aneurysm shape was a combination of a straight pipe and a half sphere, and the AR value was fixed at 1.0. The cerebral aneurysm position varied from the original position to a 180° rotated position.

Tetrahedral numerical mesh was generated with a commercial mesh generator (ICEM CFD 14.0; Ansys Inc.) for the CFD analysis. The numerical blood flow simulation was performed on a supercomputer using the commercial ANSYS FLUENT 6.3 software package and the finite volume method, and a steady flow simulation was performed. Boundary conditions were set for velocity at the inlet, pressure at the outlet, no-slip parent artery, and stent surface. Reynolds numbers at the inlet determined from the mean blood flow speed were 240 and 600.

Results and discussion: In this study, we revealed the blood flow pattern in some cerebral aneurysms using CFD. The pattern in a cerebral aneurysm was influenced by the aneurysm direction and parent artery curves. The blood flow pattern in a neck cerebral aneurysm was classified into two types.
Evaporative Particle Deposition on Superhydrophobic Surfaces
Authors: Dicuangco Mercy , Dash Susmita , Weibel Justin A. , Garimella Suresh V.
Published: April 2014

The ability to control the size, shape, and location of particulate deposits is important in patterning, nanowire growth, sorting biological samples, and many other industrial and scientific applications. It is therefore of interest to understand the fundamentals of particle deposition via droplet evaporation. In the present study, we experimentally probe the assembly of particles on superhydrophobic surfaces by the evaporation of sessile water droplets containing suspended latex particles.

Superhydrophobic surfaces are known to result in a significant decrease in the solid-liquid contact area of a droplet placed on such a substrate, thereby increasing the droplet contact angle and reducing the contact angle hysteresis. We conduct experiments on superhydrophobic surfaces of different geometric parameters that are maintained at different surface temperatures. The transient droplet shape and wetting behavior during evaporation are analyzed as a function of substrate temperature as well as surface morphology. During the evaporation process, the droplet exhibits a constant contact radius mode, a constant contact angle mode, or a mixed mode in which the contact angle and contact radius change simultaneously. The evaporation time of a droplet can be significantly reduced with substrate heating as compared to room-temperature evaporation.

To describe the spatial distribution of the particle residues left on the surfaces, qualitative and quantitative evaluations of the deposits are presented. The results show that droplet evaporation on superhydrophobic surfaces, driven by mass diffusion under isothermal conditions or by substrate heating, suppresses particle deposition at the contact line. This preempts the so-called coffee-ring and allows active control of the location of particle deposition.
Integration of Manufacturing Into Mechanical Engineering Curricula
Authors: Mott Robert , Bennett Ronald , Gartenlaub Marshall , Danielson Scott , Stratton Mark , Jack Hugh , Kraebber Henry , Waldrop Phillip
Published: April 2014

This paper focuses on enhancing the integration of manufacturing principles and concepts within curricula in mechanical engineering and mechanical engineering technology education programs. The field of manufacturing engineering covers the broad spectrum of topics derived from the definition, “Manufacturing requires that a modification of the shape, form, or properties of a material that takes place in a way that adds value”. (ABET, Inc. 2010) The ASME’s Vision 2030 surveys of industry engineering supervisors and early career mechanical engineers have illustrated that the curricula of mechanical engineering and related programs have an urgent need to enhance students’ comprehension of ‘how things are made and work,’ e.g., the knowledge and skills needed to design and efficiently produce products via high-performance systems. (Danielson, et. al. 2011) This session is designed to be primarily a dialog among the participants and the presenters, focusing on a model for the manufacturing field called The Four Pillars of Manufacturing Knowledge, developed by the Society of Manufacturing Engineers (SME 2011a), and how it relates to mechanical engineering education. Broader issues and resources related to enhancing manufacturing education are also presented.
Computational Fluid Dynamics Analysis of Pressure Drop Alteration in the Trachea Before and After Vascular Ring Surgery
Authors: Shih Tzu-Ching , Horng Tzyy-Leng , Chen Fong-Lin
Published: April 2014

The purpose of this study is to apply the computational fluid dynamics (CFD) technique to evaluate the tracheal airway pressure change before and after the vascular ring surgery (VRS) based on patient computed tomography (CT) images. Computer simulation results also show that after a surgical treatment the pressure drop in the tracheal airway was significantly decreased, especially for low inspiratory and expiratory velocities. In other words, the flow resistance in the tracheal airway becomes decreased after the VRS when the airway is expanded. The airway flow resistance of tracheal stenosis caused by CVR can be augmented by increased air flow velocity. Numerical results show that the pressure drop in the tracheal airway was 0.1099 Pa for the inlet inspiratory velocity of 10 cm/s before the VRS. After the VRS, the pressure drop was reduced and became 0.0598 Pa. In the meantime, the improvement gain was 45.58%. In word words, the pressure drop was reduced after the vascular ring surgery. Therefore, the CFD approach can be a useful method for quantifying the change of airway resistance and evaluating the effectiveness of relief of tracheal stenosis by the VRS.
Enhanced Tire Mark Visualization Using Polarization Imaging
Authors: Schwall Matthew L. , Rosenfeld Daniel E. , Wilson Joel C.
Published: April 2014

Accident reconstructions often rely on measurements of tire marks left on the roadway surface. However, accurate identification and measurement of these marks can be challenging when the marks are faint, as is often the case with braking marks left by vehicles equipped with anti-lock (ABS) brakes. This paper describes an image processing technique that exploits differences in the polarization of reflected light to create images that significantly enhance tire mark visualization. The technique requires multiple photographs taken from the same perspective, but with a polarizing filter oriented at different angles. Based on these digital images, the state of polarization of light can be determined for each pixel. A new image can then be created in which the intensity of the image is proportional to the state of light polarization. Results are presented using ABS tire marks, and demonstrate that under certain conditions the resulting image more clearly differentiates tire marks than conventional photographs or even contrast enhanced conventional photographs.
Stepwise Comparison of Expert and Nonexpert Preparations of a Polished Metallographic Surface
Authors: Sugimoto Takuya , Sakamoto Toshihiko , Kuwahara Yoshiaki , Koshino Tetsushi , Endo Atsushi , Takai Yuka , Goto Akihiko
Published: April 2014

The carburizing process requires metallurgical inspection by means of polished metallurgical mounts. Metallographic preparation for a metallurgical mount is an important process. The purpose of this study is to clarify the differences in ground and polished surface finishes of metallurgical mounts for carburized parts at each step of the process as executed by an expert and a nonexpert on a semi-automated grinding and polishing machine.

To clarify the differences between expert and nonexpert preparations, microscopic images of the surface finish obtained at each step of grinding and polishing were compared. The surface profile of each of the final finishes was also examined with measuring device. Each inspector has either 20 (expert) or 0.5 years (nonexpert) of experience in metallographic preparation. The ground and polished finish produced by the expert was well balanced over the entire surface. In contrast, the surface finish produced by the nonexpert was dispersed. The number of scratches and edge rounding depth apparent in the final surface finish of the expert were less than those of the nonexpert.
Investigating the Effects of the Friction Coefficient and Tool Geometry on the Cup Thickness in the Deep Drawing Process of SPXI250 Alloy
Authors: Rostamsowlat Iman , Afsari Ahmad , Janghorban Maziar
Published: April 2014

In this paper, effects of friction coefficient and tool geometry on the thickness variations of a cylindrical cup were studied. Blank is made of SPXI250 alloy sheet which was analyzed by Finite Element Method (FEM). This not been studied yet. Finite Element modeling of the deep drawing process was conducted using ABAQUS/EXPLICIT software. A set of appropriate die and punch were designed for experimental tests. The results of the simulation showed that a change in the friction coefficient of the die-blank interface leads to a significant changes in the cup thickness. Moreover, the results revealed that the influence of die nose radius on the final cup thickness variations is greater than that of the punch nose radius. The simulation results of this study were compared with the experimental results and those of the other investigators’. The comparisons of the experimental and simulation results with those of the other researchers were so satisfactory.
Localized Elastography Map of Human Cornea Through Surface Vibrations
Authors: Khan Altaf A. , Dai Zoujun , Cortina Soledad , Chamon Wallace , Royston Thomas J.
Published: April 2014

Elastography techniques are being developed to diagnose and monitor the progression and treatment of diseases that correlate with changes in soft tissue stiffness. The objective of this paper is to outline the application of vibrations to the human cornea in order to reconstruct a stiffness map. Having a localized stiffness map is useful for early diagnosis of cornea related diseases such as glaucoma and keratoconus. Experimental data was collected by directly vibrating the excised cornea axisymetrically along the edge and measuring wave propagation inward with the use of laser vibrometry. Different methods have been implemented to increase the reflectivity of the cornea for laser vibrometry. To corroborate the data, as well as to test feasibility, experiments have been done on phantoms constructed from silicone-based polymers. To reconstruct the data into a stiffness map, an appropriate analytical model has to be derived. This paper outlines the derivation of the analytical model for the cornea starting with simple circular plates and moving towards the curved geometry of the cornea. To verify the analytical model, finite element simulations were used to replicate the results. These results have also been checked against experimental data to help determine any external variables that affect results. Overall, the feasibility and application of a process has been determined. Future goals include increasing in-vivo application to make the process safe and cost-effective.
Multidimensional Thermal-Hydraulic Analysis on Natural Circulation Behavior in Ex-Vessel Fuel Storage Tank of MONJU
Authors: Ohno Jun , Mori Takero , Sotsu Masutake , Ohira Hiroaki
Published: April 2014

Since the accident of the Fukushima Dai-ichi Nuclear Power Station, analysis evaluations for stress tests have been conducted on the prototype fast breed reactor MONJU. In these evaluations, it has been necessary to evaluate the plant characteristics including the Ex-Vessel fuel Storage Tank (EVST) under the severe accident conditions such as station blackout. The EVST is a coaxial cylindrical tank to store spent fuels (SFs) stored in fuel transfer pots (FTPs) until the radioactivity enough decays. It is able to store 252 fuel transfer pots in the rotating rack and cool them by internal natural circulation of sodium coolant under both the severe accident and normal operation. The heat produced by SFs removed by the helical cooling coils installed in the annular space.

Evaluations of natural circulation in the EVST have been performed with a one-dimensional flow-network code. However, it would be difficult to predict its behavior exactly, because it would include multidimensional flow such as local natural convection. Then, in order to clarify the natural circulation behavior and multidimensional effects and evaluate appropriateness of this flow network model, we have performed a thermal-hydraulic analysis using a three-dimensional model which has high resolution meshes and the almost same geometry as the actual equipment. This model makes it possible to take into account the following multidimensional phenomena, the heat distribution of the FTPs, the mixing in plenums, the bypass flow through the flow holes and the other geometry effects.

In this study, we have used a commercial computational thermal-hydraulics code, “FrontFlow/red”. As a result of steady analyses, we have confirmed the following: The coolant temperature in the plenums is almost uniform and its difference is in a few degrees. The influence of the flow holes is also limited because its flow rate is relatively low to main flow rate. On the other hand, pressure loss at supporting plates of the rotating rack, which are main causes of flow resistance in the EVST, is larger than the case without multidimensional effects because of the natural convection concentrated in the high temperature region near heated FTPs. The result leads to our presumption that the flow network model of the EVST is almost appropriate. It should be noted that flow resistance coefficient of the supporting plates or the heat transfer center of the cooling coils should be set to conservative for the safety analysis on the EVST.
Performance Analysis of a Simplified Model of Cooling Load for a Typical Office Building
Authors: Ogunsola Oluwaseyi T. , Song Li
Published: April 2014

Buildings are responsible for at least 40% of energy use in most countries of the world, and for up to 21% of greenhouse gas emissions globally. As this trend continues, real-time building load measurements are essential for dynamic load response control, understanding and improvement of load distributions and profiles, and for climate-responsive design, particularly in commercial buildings. The focus in this paper is the cooling load, which is the rate at which heat must be removed from the controlled zone to maintain the desired temperature. Estimation of maximum cooling load is necessary for sizing of cooling equipments. However, details needed for whole-building simulation are often unreliable or unavailable. As such, simplified models with reasonable accuracy and computational requirements are often used. A cyber-physical system, integration of physical sensors and mathematical model, is proposed in this paper for cooling load estimation. The physical sensor measurements are limited to outside air temperature, solar radiation, room air temperature, and building plug load. Meanwhile, resistance-capacitance (RC) concept was adopted to describe the physics and dynamics of the building envelope for its simplicity and reasonable computational requirements. The cyber-physical system was tested using a typical office having two thermal zones and compared with simulation results from EnergyPlus, a whole building simulation program. Phenomenon such as infiltration, inter-zone air mixing, and air moisture control were not taken into account for the model. Results are presented to determine the accuracy of the simplified model for cooling load estimation.
Nonlinear Dynamics of Ligament Deficient Knees in Proximal-Distal Tibial Oscillatory Motion
Authors: Caruntu Dumitru I. , Granados Eduardo , Martinez Thania A.
Published: April 2014

This paper deals with nonlinear dynamics of deficient knees. A two dimensional model of the human knee to include tibia and femur, and the ligamentous structure between the two bones is used to investigate the nonlinear dynamics of the knee in order to differentiate between normal and deficient knees. An exercise in which the femur is pinned at the hip in a sitting position, and tibia in a vertical position is actuated by a vertical soft harmonic force at various frequencies is proposed. A significant difference between the behavior of normal knees and Anterior Cruciate Ligament (ACL), and Posterior Cruciate Ligament (PCL) deficient knees is predicted.
The Effect of Geometry on Sample Leakage in Multi-Channel Microfluidic Devices
Authors: Rafie Borujeny Elham , Xu Zhenghe , Nazemifard Neda
Published: April 2014

Electrokinetic sheath-flow is one of the techniques used to manipulate sample migration and prevent cross-contamination in multi-channel microfluidic devices. To achieve a successful design, it is important to predict the sample behaviour in advance. We use finite element method to investigate the effect of channel geometry on sample leakage in the presence of electrokinetic sheath-flow. A typical multi-channel device consisting of a main fractionation channel connected to a few collection channels is considered. It has been observed experimentally that the depth of different components of the microfluidic device can change the sample leakage. In-detail investigations are made here in order to find the fundamental cause of the observed behaviour. Simulation results confirmed that by increasing the depth ratio of the collection channels to the main channel the sample leakage would decrease. Simulations are also performed to find criteria for choosing an optimum depth ratio for the channels in terms of both high functionality and ease of fabrication for any specific application.
Dynamic Performance Simulation of an Aeroderivative Gas Turbine Using the Matlab Simulink Environment
Authors: Tsoutsanis Elias , Meskin Nader , Benammar Mohieddine , Khorasani Khashayar
Published: April 2014

In fossil fuel applications, such as air transportation and power generation systems, gas turbine is the prime mover which governs the aircraft’s propulsive and the plant’s thermal efficiency, respectively. Therefore, an accurate engine performance simulation has a significant impact on the operation and maintenance of gas turbines as far as reliability and availability considerations are concerned. Current trends in achieving stable engine operation, reliable fault diagnosis and prognosis requirements do motivate the development and implementation of real-time dynamic simulators for gas turbines that are sufficiently complex, highly nonlinear, have high fidelity and include fast response modules.

This paper presents a gas turbine performance model for predicting the transient dynamic behavior of an aeroderivative engine that is suitable for both mechanical drive and power generation applications. The engine model has been developed in the Matlab/Simulink environment and combines both the inter-component volume and the constant mass flow methods. Dynamic equations of the mass momentum and the energy balance are incorporated into the steady state thermodynamic equations. This allows one to represent the engine model by a set of first order differential and algebraic equations. The developed Simulink model in an object oriented environment, can be easily adapted to any kind of gas turbine configuration. The model consists of a number of subsystems for representing the gas turbine’s components and the thermodynamic relationships among them. The components are represented by a set of suitable performance maps that are available from the open literature.

The engine model has been validated with an established gas turbine performance simulation software. Time responses of the main variables that describe the gas turbine dynamic behavior are also included. The proposed gas turbine model with its dynamic simulation characteristics is a useful tool for development of real-time model-based diagnostics and prognostics technologies.
Numerical Investigation of Heat Transfer, Fluid Flow and Formation of Emissions in Diesel Engines
Authors: Firat Müjdat
Published: April 2014

The present study has been performed on heat transfer, fluid flow and formation of emissions in a diesel engine by different engine parameters. The analysis aims at an investigation of flow field, heat transfer, combustion pressure and formation of emission by means of numerical simulation which is using as parameter; hole number of injector and crank angle. Numerical simulations are performed using the AVL-FIRE commercial software depending on the crank angle. This software is successfully used in internal combustion engine applications, and its validity has been accepted. In this paper, k-zeta-f is preferred as turbulence model and SIMPLE/PISO used as algorithms. Thus, results are presented with pressure traces, temperature curves and NOx and soot levels for engine operating conditions. In addition, the relationship between the spray behaviors and combustion characteristics including NOx emissions, soot emissions, combustion pressure and temperature were illustrated through this analysis.
A Two-Feet Linear Ultrasonic Motor for Fuze Safety System
Authors: Tang Y. J. , Wang J.
Published: April 2014

In modern weapons systems, fuze is known as the “brain” of the ammunition, whose performance will directly affect the combat effectiveness. It guarantees the safety of ammunition during the logistical processing and makes the ammunition reliably function after launch. In the fuze system, the delay arming device is closely related to the fuze performance and safety reliability, which affects the muzzle safety distance. After years of development, the performance of delay arming device has been developed and improved, but malignant accidents such as explode in the chamber, early burst and dud have occurred from time to time.

This paper investigated a standing wave linear ultrasonic motor applied to the fuze delay arming device as the arming actuator. The motor is made up of a cuboid with two drive feet and a slider with a convex part, both having a through hole. The first order longitudinal vibration and second order bending vibration of the stator were selected as working modes. The prototype was fabricated and the vibration mode test was carried out, indicating the motor can generate two-phase required oscillation modes. The frequency sweep test was also performed and two-phase frequency is proved quite close. The experiments on the motor mechanical performance were done, and the speed of the motor is 88.2 mm/s, furthermore the reciprocating motion of the slider is flexible.
Nonlinear Transient Response of Tilting 4 Pad Bearings: Turbocharger Systems
Authors: Ying Jiayang , Jiao Yinghou , Chen Zhaobo , Kirk R. Gordon , Feng Yongxin
Published: April 2014

High speed and high performance engines are often equipped with turbochargers to increase power density over the operating speed range. Tilting pad bearings are now much more applied in many types of rotor systems. This paper presents nonlinear dynamical behavior of a typical turbocharger supported by two tilting 4 pad bearings. The bearing oil-film force was calculated by a database method and the influence of both pad offset and preload were studied. The nonlinear transient vibration is represented by bifurcation diagrams. The results directly show that pad offset and preload greatly influence the nonlinear vibrations of the turbocharger-tilting pad bearings system. In some certain speed range, the motions of the bearing pads are different from that of the bearing journal centerline.
Geometrically Nonlinear Vibration Analysis of Thin-Walled Composite Beams
Authors: Durmaz Seher , Kaya Metin O.
Published: April 2014

In this study, accounting for large displacements a geometrically nonlinear theory, which is valid for laminated thin-walled composite beams of open and closed cross sections, is developed. The beam model incorporates a number of non-classical effects such as material anisotropy, transverse shear deformation and warping restraint. Moreover, the directionality property of thin-walled composite beams produces a wide range of elastic couplings. In this respect, symmetric lay-up configuration i.e. Circumferentially Asymmetric Stiffness (CAS) is adapted to this model to generate coupled motion of flapwise bending-torsion-flapwise transverse shear. Initially, free vibration analyses are carried out for the linear model of the shearable and the non-shearable thin-walled composite beams. Similar to the linear model, the displacement-based nonlinear equations are derived by the variational formulation, considering the geometric non-linearity in the von Karman sense. Finally, the static and the dynamic analyses for the nonlinear beam model are carried out addressing the effects of transverse shear, fiber-orientation and sweep angle on the nonlinear frequencies and the static response of the beam.
Magnetic Field Enhancement in Water-Lithium Bromide Absorption Refrigeration Systems
Authors: Odunfa K. M. , Fagbenle R. O. , Oyewola M. O.
Published: April 2014

Absorption refrigeration systems are generally characterized by low Coefficient of Performance (COP). Absorption enhancement is an effective way of improving the COP of refrigeration systems. Literature is sparse on the use of magnetic field for the enhancement of absorption refrigeration systems despite its cheapness and environmental friendliness as compared with other enhancement methods. Although the method has recently been employed on ammonia solution, its influence on lithium bromide (LiBr) solution is yet to be fully studied. In this paper a numerical model for the magnetic field enhancement in water-LiBr absorption systems was developed and evaluated.

The flow within the film thickness to the absorber wall was considered as a two-dimensional steady laminar flow. A Finite Difference model was developed based on conservation of mass, momentum, energy equations and mass transport relationship. The model was validated using data from the literature on ammonia solution. Standard parameters including absorber wall length (1 m), film thickness (10–3 m), magnetic field vacuum permeability (1.257 × 10–6 kgmA-2s2), magnetic mass susceptibilities and magnetic induction intensities were used for LiBr solution’ modeling. Changes in their concentrations, both in the direction of falling film and across its thickness, were investigated. Data were analysed using descriptive statistics and Student’s t-test (p = 0.05).

The concentration distribution of lithium bromide solution in the direction of falling film was between 54.9% and 60.0% for the magnetic induction range of 0.0 and 3.0 Tesla. Across the film thickness and for the same range of magnetic induction, the concentration distribution was between 0.0 and 0.19. The concentration of the solution increased from 0.0 to 21.7 when magnetic induction was increased from 0.0 to 3.0 Tesla, implying higher cooling effect. The COP of lithium bromide solution absorption refrigeration system was increased by 0.3% for magnetic induction of 3.0 Tesla.

Magnetic field enhanced the absorption performance in the lithium bromide solution; hence can be used in typical absorption refrigeration systems.
Comparison of Dynamic and Aerodynamic Characteristics of the Centrifugal Fan Calculated by Different Methods
Authors: Gášpár Roman , Kalmár László , Polanský Jiří
Published: April 2014

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic “A” variant contains 12 blades. The geometry of second “B” variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant “C” contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys and OpenFoam.

Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated for to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using of frequency analysis for the each variant and working condition.
Detection of Subsurface Skin Lesion Using Frequency Modulated Thermal Wave Imaging: A Numerical Study
Authors: Bhowmik Arka , Repaka Ramjee , Mishra Subhash C. , Mulaveesala Ravibabu
Published: April 2014

Infrared thermography is one of the promising and non-invasive imaging approaches which can be performed either in passive or in active mode. Due to its inherent capabilities, viz., fast, safe and subsurface feature extraction, this technique has been widely used in bio-medical imaging. In conventional passive approach, imaging may not provide enough contrast for detection of subsurface skin lesion. However, this limitation can be surmounted by using active thermography technique in which controlled energy is being supplied to the skin. This controlled stimulus not only helps in the detection of deeper subsurface details but also helps in getting the quantitative information of hidden features. Apart from the various widely used active approaches such as modulated lock-in thermography (LT) and high peak power pulsed based thermography (Pulsed Thermography - PT and Pulse Phase Thermography - PPT) techniques, the present article highlights an alternative approach which can be performed in less time as compared to LT and with much less peak powers as compared to pulsed based thermography (PT and PPT) techniques.

The present work utilizes a non-stationary thermal wave imaging approach to map the subsurface skin lesion. The multilayered skin has been modeled and simulated for a given frequency modulated heat stimulus using 3-dimensional bio-heat equation.
A Constitutive Model for Soft Tissue and its Application to a Boundary Value Problem
Authors: Mythravaruni P. , Ravindran Parag
Published: April 2014

Mechanical loading induces changes in the structure and function of soft tissue. Growth and remodeling results from the production and removal of constituents. We consider a tissue constituted of elastin and collagen. The collagen turns over at a much higher rate than elastin. In this work we propose a two-constituent, constrained mixture model for this soft tissue. One constituent is modeled as a viscoelastic material and the other as an elastic material. It is assumed that the collagen turns over depending on the stress applied and the elastin does not turn over. The standard mixture theory approach is followed and the balance equations are set-up. The model is studied in simple uni-axial loading to test its efficacy.
Non Linear Multibody Modelling for the Vibrational Prevision of the Shift Lever of Automotive Gearboxes
Authors: Landi L. , Braccesi C. , Cianetti F.
Published: April 2014

The main task of this paper is to identify and formalize “design methodologies” useful to highlight/solve any possible problem due to the vibrations of a new gear box command system in each design stage of this component. In particular, we focused on the so-called phenomenon of “shift lever vibration” (SLV - vibration of the shift leverage in the car cabin). This phenomenon can occurs if a natural frequency of the control system is excited by a movement of the so called shift collars in the gear box. Therefore an unwanted low level of comfort and high level of noise and vibration can be experienced by the car driver. In this paper we will explain in detail the SLV phenomenon by measuring a real shift command during acceleration/deceleration manoeuvres. Then we will present two different types of multibody models developed to predict this phenomenon: the first simple-linear one is useful to “predict” the first natural frequency of the shift lever vibration. The first one can be used in the early design stage of the main components of the gearbox control. It is useful to the designer to perform a sensitivity analysis of the most important parameters to be taken into account to prevent the SLV in the cabin of the car. The second complete nonlinear multibody model is useful, not only to take into account all the non-linear aspects of the phenomenon (different behaviours in acceleration and deceleration manoeuvres), but also to predict the level of acceleration in the shift lever. The results obtainable with the multibody approach will be then compared with the results from experimental data of a real shift command.
Direct Adaptive Control of Discrete-Time Infinite-Dimensional Systems in a Hilbert Space
Authors: Balas Mark J. , Frost Susan A.
Published: April 2014

Given a linear discrete-time infinite-dimensional plant on a Hilbert space and disturbances of known waveform but unknown amplitude and phase, we show that there exists a stabilizing direct model reference adaptive control law with certain disturbance rejection and robustness properties. The central result is a discrete-time version of Barbalat-Lyapunov result for infinite dimensional Hilbert spaces. This is used to determine conditions under which a linear Infinite-dimensional system can be directly adaptively regulated. Our results are applied to adaptive control of general linear diffusion systems.
Dynamic Classification: A Tool for Fault Detection and Vibration Behavior Monitoring of Bearings
Authors: Kerroumi Sanaa , Rasolofondraibe Lanto , Chiementin Xavier
Published: April 2014

The emergence of a defect in a mechanical system is always associated with a change in the vibration’s behavior in the spectral and temporal domains. Fault detection by vibration analysis is based on monitoring the behavior of a mechanical component by examining the evolution of fault indicators in real time. However, mere traditional bearing diagnosis is not sufficient to ensure effective and reliable assessment of the component’s health condition. Coupling several fault indicators extracted by different signal processing technique adds more reliability and accuracy to the diagnostic process.

Classifications methods are used to analyze the evolution of fault, yet only static methods are solicited which results in overlooking a great source of useful information.

In fact, fault indicators issued from turning machine are evolving; they change constantly over time, particularly when the defect is growing. In such situations, static classification methods are a poor choice that deprives the user of the information conveyed in the evolution of the indicators over time.

The dynamic classification of fault indicators in dynamic classes can provide useful information about the behavior of the damaged bearings. This information can also be used to predict the end of life of the components.

Unlike the static classification, the dynamic classification introduces a new dimension (time), which allows real-time detection of the fault and better visibility of the bearing behavior revealed by the motion and the temporal evolution of classes formed by the indicators.

This paper proposes a dynamic classification method that uses several fault detectors to assure the accuracy of the diagnostic and follow up any changing in the behavior of the bearing by analyzing the classes’ time evolution.

The proposed multi-features dynamic classification is a new method for fault detection and health condition monitoring for bearings; this technique utilizes multiple features, including traditional features extracted from the raw signal, two special features extracted by wavelet analysis, and the spectral kurtosis, coupled with a nonlinear principal component analysis.

This method of classification clusters the multi-features into several classes, the first class represents the healthy state of the bearing, and the other classes represent different damaging state. Monitoring the evolution of the” defective condition” class allows us to draw several useful information, such as the rate of degradation, the relationship between the cluster’ surface and density and the bearing state.

The chosen dynamic classification method will be validated by analyzing several degradation bearings from a fatigue bench of thrust ball bearings SNR51207.
Development of High Stiffness Axle for a Race Vehicle
Authors: Jung Jin Ho , Lim Dong Min , Lee Jae Kil , Kim Seon Pyung
Published: April 2014

In rallies, it is required to develop the high stiffness and high strength suspension parts in order to maximize the handling performance and reliability to severe race condition. To determine which part we should focus on among the suspension parts in the development stage, it is required to consider the driving condition and the various rally road conditions.

First, it is necessary to increase the lateral stiffness and camber stiffness of suspension systems in order to maximize the handling and cornering performance. As the result of finite element (FE) analysis for production car suspension, it is verified that the stiffness of axle assembly affects mainly on the lateral stiffness of suspension system. Second, the shock loads under severe conditions such as landing after jump and bumpy road and the driving and braking torque are concentrated on the axle assembly. As the result of above consideration, developing the high stiffness and high strength axle has been considered as the most important work for the project of rally car suspension development.

For the development of new prototype car, hub and upright have been newly developed and new big bore wheel bearing has been selected in order to increase the stiffness of axle assembly. Newly developed suspension components have been installed in the new prototype car and 3 different test cars have been introduced to verify the effect of high stiffness axle.

Finally, Kinematic and Compliance (K&C) test result for these 3 test cars shows that the stiffness of axle assembly is the most significant parameter to increase the lateral stiffness of whole suspension system.
Experimental Investigation of the Performance of a Micro Gas Turbine Fueled With Mixtures of Natural Gas and Biogas
Authors: Nikpey Homam , Assadi Mohsen , Breuhaus Peter
Published: April 2014

Previously published studies have addressed modifications to the engines when operating with biogas, i.e. a low heating value (LHV) fuel. This study focuses on mapping out the possible biogas share in a fuel mixture of biogas and natural gas in micro combined heat and power (CHP) installations without any engine modifications. This contributes to a reduction in CO2 emissions from existing CHP installations and makes it possible to avoid a costly upgrade of biogas to the natural gas quality as well as engine modifications. Moreover, this approach allows the use of natural gas as a “fallback” solution in the case of eventual variations of the biogas composition and or shortage of biogas, providing improved availability. In this study, the performance of a commercial 100kW micro gas turbine (MGT) is experimentally evaluated when fed by varying mixtures of natural gas and biogas. The MGT is equipped with additional instrumentation, and a gas mixing station is used to supply the demanded fuel mixtures from zero biogas to maximum possible level by diluting natural gas with CO2. A typical biogas composition with 0.6 CH4 and 0.4 CO2 (in mole fraction) was used as reference, and corresponding biogas content in the supplied mixtures was computed. The performance changes due to increased biogas share were studied and compared with the purely natural gas fired engine. This paper presents the test rig setup used for the experimental activities and reports results, demonstrating the impact of burning a mixture of biogas and natural gas on the performance of the MGT. Comparing with when only natural gas was fired in the engine, the electrical efficiency was almost unchanged and no significant changes in operating parameters were observed. It was also shown that burning a mixture of natural gas and biogas contributes to a significant reduction in CO2 emissions from the plant.
Emissions and Performance on a Jatropha Oil Methyl Ester Fueled Diesel Engine With Retarded Injection Timing
Authors: Suryawanshi J. G.
Published: April 2014

Injection timing variations have a strong effect on NOx emissions for direct injection diesel engines. Retarded injection is commonly used to control NOx emissions. Biodiesel is a non-toxic, biodegradable and renewable fuel with the potential to reduce engine exhaust emissions. The methyl ester of jatropha oil, known as biodiesel, is receiving increasing attention as an alternative fuel for diesel engines. In the present investigation neat jatropha oil methyl ester (JME) as well as the blends of varying proportions of jatropha oil methyl ester (JME) and diesel were used to run a CI engine with standard injection timing and retarded injection timing. Significant improvements in engine performance and emission characteristics were observed for JME fuel. The addition of JME to diesel fuel has significantly reduced HC, CO, and smoke emissions but it increases the NOx emission slightly with standard injection timing. The NOX emission was decreased with retarded injection timing with negligible effect on fuel consumption rate. Similar trend in brake thermal efficiency and exhaust gas temperature was observed with retarded injection timing while maximum cylinder gas pressure and ignition delay was decreased.
Wake Structures of a Cantilever Beam Excited by Piezoelectric Actuators
Authors: Wang S. S. , Li H. , Tzou H. S.
Published: April 2014

In this paper, the wake structures of a cantilever beam in axial flows under the excitations of piezoelectric actuators are studied. It is assumed that the dynamic response of the cantilever beam is relatively small (i.e., linear) and the beam is modeled as an Euler-Bernoulli beam. The total force is divided into two parts: 1) the hydrodynamic loading, which changes beam’s natural frequencies and damping ratios and 2) the piezoelectric induced part, which is the excitation force. Furthermore, the hydrodynamic loading can be separated into an added mass term and a fluid damping term and they are obtained with the hydrodynamic function; the excitation force induced by the converse piezoelectric effect is calculated with Love’s control operator. In order to maximize wake generations, two specific types of piezoelectric actuators (i.e., modal actuators and segmented actuators) are used in this study. It is assumed that the mode shapes of the cantilever beam remain unchanged in fluids and the dynamic responses of the cantilever beam can be calculated by the modal expansion method. Once the dynamic responses of the cantilever beam are known, the panel method free-wake model is adopted to simulate the wake structures. In case studies, the wake structures excited by modal actuators and segmented actuators of the first four modes are compared. The effects of applied voltage and flow velocity to the wakes are also studied. Distinct wake roll-up phenomenon is observed in all simulation results. Higher applied voltage and lower flow speed make the wake easier to roll-up.
Use of Forward Dynamics Model for Designing Large-Size Wind Turbine Blades
Authors: Bayoumy Ahmed H. , Nada Ayman A. , Megahed Said M.
Published: April 2014

In this paper, the Blade Element Momentum (BEM) theory is used to design the horizontal wind turbine blades. The design procedure concerns the main parameters of the axial/angular induction factors, chord length, twist/attack angles, and local power/thrust coefficients. These factors in turns affect the blade aerodynamics characteristics and efficiency at the corresponding nominal speed. NACA 4-digits airfoil geometry is obtained, using BEM theory, to achieve the maximum lift to drag ratios. The optimization of the power coefficient and its distribution versus different speeds is carried out by modifying the twist angle and chord length distribution along the blade span. The dynamic characteristics of both the original and optimized design are examined through forward dynamic simulation of the blade model. Since large-size wind turbine blade is considered, the dynamic model is established using the Absolute Nodal Coordinate Formulation (ANCF), which is suitable for large-rotation large-deformation problems. Finally, in order to verify the dynamic enhancements in the Aerodynamic/Structural properties, the fluid-solid interaction simulation for both the original and optimized model is performed using ANSYS code. The obtained results show a good rank of the proposed optimization procedure for a practical case of wind data upon Gulf of Suez-Egypt.
Experimental Investigation on the Condensation Efficiency of Humid Air in a Cross-Flow Condenser
Authors: Ahn Hojin , Gul Burhan , Sahin Yavuz , Hartoka Onur
Published: April 2014

The condensation of steam in the presence of air has been investigated experimentally in the cross-flow flat-plate single-channel condenser. In particular, the condensation efficiency which is defined by the ratio of heat released during the condensation process (the amount of latent heat) to the total heat extracted from the mixture of vapor and non-condensable gas (the sum of latent and sensible heats) is examined as a function of the air-steam mixture temperature and humidity at inlet and the flow rates of the air-steam mixture and cooling air. The preliminary results are obtained with the operating condition of the air-steam mixture flow at 70°C and 80, 85 and 90% relative humidity at inlet. The most notable result is that the condensation efficiency evidently decreases with the increase of the cooling air flow rate. With both mixture and cooling flow rates kept constant, the condensation efficiency increases, as expected, with the increasing air-steam mixture humidity at the inlet. On the other hand, the air-steam mixture flow rate appears to have little effect on the condensation efficiency.