bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Evaluation of Mental Stress Level Using a Modified Duffing Oscillator
Authors: Miyago Kentaro , Uehara Kenyu , Mori Koji , Saito Takashi
Published: February 2017

The decrease of arousal level has led to serious accidents in driving and operation of machine. A system to accurately evaluate arousal level in real time is required to prevent such accidents. In this paper, we examined whether parameters of the mathematical model, which are determined in each time shifting window using EEG data could be used as a method to evaluate the arousal level. The modified Duffing oscillator was proposed as a mathematical model to perform simplified parameters calculation and identification. It was applied to EEG data, which is obtained by EEG acquisition experimentation in alternative repeat of relaxed and concentrated state. As a result of the parameters identification in theta band, alpha band, beta band, and 4–30 Hz band, it is shown that each parameter is repeating increase and decrease with time progress of each experiment. Especially, the relationship between the conventional arousal level and parameter B, which is the coefficient of the proportional term in the modified Duffing oscillator shows a significant correlation. It is suggested that parameter B of the modified Duffing oscillator would evaluate the arousal level. Since this evaluation method of arousal level does not require analyzing for each band, it can be used to calculate the arousal level in real time.
Gait-Monitoring Wearable Technology for Transtibial Prosthetics
Authors: Hebert Kolby V. , Keen Rachel S. , King Derek R. , Shady Sally F.
Published: February 2017

Approximately 40,000 transtibial amputations occur each year in the United States. Current lower leg prosthetic options range from passive artificial limbs to computerized electronic models [1]. Because of insurance limitations, most patients use less sophisticated prosthetics. The average cost of lower leg prosthetics and corresponding medical care for single-leg veterans is at least $1.4 million due to increased rehabilitation times [1]. Gait training methods for transtibial amputees include extended rehabilitation processes lasting up to 9 months. These exercises provide no empirical data to analyze patient gait progress.

The device design is a wearable technology that acquires gait information that is evidentiary for physicians when deciding to continue or dismiss further rehabilitation and follow up medical appointments. The technology includes a gyroscope, accelerometer, microprocessor, and electronic components housed in a 3D printed casing that is attachable to any prosthetic, or a biological leg. Pressure sensors are embedded into a sock-like foot covering that is used in tandem with the other electronics.

Gait data collection was validated by comparing gait parameter values with literature values. A series of control tests on non-amputees was conducted in order to gather standard data and develop consistent testing practices for the prototype design. These findings are used as a reference when evaluating amputee gait data against non-amputee gait data.

As the microprocessor collects data, information is stored onto a memory card used to relay data to the developed program for data analysis. Data analysis is supported by a graphical user interface via LabView which provides valuable gait data to physicians and physical therapists. Gait data analysis is expected to result in asymmetrical patterns for below-the-knee amputees compared to non-amputees as well as abnormal pressure loads throughout the foot [1].
Development of 3D Finite Element Model for Predicting Process-Induced Defects in Additive Manufacturing by Selective Laser Melting (SLM)
Authors: Hussain Bilal , El-Gizawy A. Sherif
Published: February 2017

Selective Laser Melting (SLM) is one of the important Additive Manufacturing techniques for building functional products. Nevertheless, the absence of accurate models for predicting the SLM process behavior, delays development of cost effective and defects free process. This work presents a coupled thermo-mechanical numerical model to capture the two phase (solid-liquid) solidification melting phenomena that occur in the process. The proposed model will also predict the evolvement of process-induced properties and defects particularly residual stresses caused by temperature gradient and thermal stresses. CO2 or Nd:YAG laser beam can be used as a heat source with a Gaussian distribution for the laser beam energy.
Experimental Investigation on Liquid Infiltration Speed in Liquid Nanofoam
Authors: Li Mingzhe , Lu Weiyi
Published: February 2017

Liquid nanofoam (LN) as a novel material for energy absorption applications exhibits superior properties, including high energy absorption efficiency, ultra-fast energy dissipation, light weight and small size, over existing options. It is a liquid suspension of nanoporous particles, whose nanopore surface is non-wettable to the liquid molecules. Past studies on LN have focused on quasi-static responses, and the actual system performance under dynamic loadings has remained unclear. In this study, the mechanical behavior of two types of LN samples at various strain rates and the liquid flow speed in the nanopores have been experimentally investigated.

The quasi-static behavior of LN is rigorously characterized by an Instron 5982 universal tester, from which we find that large amount of energy is dissipated into heat due to the effective excess solid-liquid interfacial tension, and confirm that the energy absorption efficiency of the LN is determined by the liquid infiltration pressure and the total deformability.

The dynamic behavior of the LN is investigated by impacting it with a lab-customized drop tower apparatus at intermediate strain rates (around 102 s−1), from which the measured strain-stress curves are highly hysteretic. By comparing with the quasi-static sorption isotherm curve, we show that the liquid infiltration pressure as well as the total deformability of the LN sample in liquid marble form is not affected by the increased strain rate. This suggests that the dynamic behavior of LN can be characterized by quasi-static compressive tests.

In the dynamic tests, the ultra-fast energy dissipation rate of LN indicates that the real liquid flow speed in nanopores is much higher than that predicted by the continuum theory. The flow speed can be directly measured from the strain rate by considering the total surface area of the nanoporous particles exposed to the liquid phase. The flow speed is related to the external remote pressure and the 3D porous structure of nanoporous particles.

We have examined for the first time the dynamic behaviors of LN, and demonstrated the energy absorption capacity of LN can be activated at desired pressure range by virtue of the strain rate-independent liquid infiltration behavior. This is the first experimental approach to characterize the liquid flow speed in nano-environment. These findings provide strong evidence supporting the potential application of LNs to mitigate energy in blunt impact scenarios such as head to head and head to shoulder collisions in sports, traffic accidents and ballistic impact.
Numerical Analysis of Texture Tactics on Skin by Using of the Model of Periodic Micro Unit
Authors: Ishino Takayuki , Sakuma Atsushi
Published: February 2017

Various mechanical effects occur in the human skin when it touches the texture which has micrometric scale. Since these mechanical effects in the skin are complicated, their study is necessary. The purpose of this study is to ascertain these mechanical effects by applying numerical analyses for a detailed discussion. In particular, the analysis confirms the differential effects in the skin due to a periodic variation of the texture. By the modeling situation that the texture touches the skin, a stress in the position of skin sensory organs is examined. As a result of the analysis, von Mises stresses at a shallow position of skin showed characteristic effects in the case of a large texture period. It is inferred that these effects occur with a texture period greater than a certain boundary value. Stress values at deep positions of skin are substantially equal without depending on the pressure position of the skin surface. In other words, skin sensory organs of the deep position have a wide receptive field in the numerical analysis of this paper, and this result matches with results of previous researches.
Effect of Micro Scale Textures on Drilling Performance of Carbide Tools in Dry and Wet Machining of Ti-6Al-4V
Authors: Saseendran Niketh , Gonumakulapalle Lodi Samuel
Published: February 2017

Surface textures helps in controlling the tribological, optical, mechanical, and thermal properties on the surfaces. The recent advancements in precision machining, makes it possible to generate micro/nano patterns on the surfaces with high dimensional control. In the present work an attempt has been made to reduce the thrust force and torque developed during drilling super alloy, Ti-6Al-4V by creating micro dimples on the tool surfaces. Circular dimples having an average diameter of 35 micrometer were created on the flute and margin side of the drill bit using Nd:YAG laser. Scanning electron microscopy analysis has been done to evaluate the quality of generated micro dimples. Drilling experiments were carried out on the titanium alloy in both dry and wet conditions using flute textured, margin textured and non textured tool for understanding the effect of micro textures on the tool. From the force analysis it was observed that in both dry and wet conditions there was a considerable reduction in thrust force and torque. Surface inspections of the drill bit were performed using Stereomicroscope for investigating the titanium buildup on the cutting tool surfaces. Results showed that the margin textured tool performed better than the flute textured and untextured tool in both dry and wet conditions.
Measuring Compressive Modulus of Elasticity Across Cortical Bone Thickness of Mid-Diaphysis Bovine Femur
Authors: Hage Ilige S. , Seif Charbel Y. , Hamade Ramsey F.
Published: February 2017

The aim of this study is to quantitatively discern the compressive stiffness along the thickness of bovine cortical bone from the inner surface toward the bone’s periosteum (outer) surface. Ring-shaped bone slices from randomly selected 3 cow bovine bones were cut from mid diaphysis femur. Micro hardness measurements (ASTM E384-11e1 Standard- test method for Vickers hardness of materials with load of 500gf and dwelling time of 10s) were conducted along radial lines emanating from the geometric center of the bone transverse cross section. Values of compressive stiffness (longitudinal young’s modulus, E11) using the slope of the unloading curve of micro hardness tests at maximum load were extracted per the method advanced by Oliver and Pharr. Fitting these data points in a linear fit resulted in statistically significant and simple linear equations for compressive modulus as function of radial distance. For the anatomical anterior and posterior regions, compressive modulus values were found to range from 18 to 23.4 GPa (average of 21.2 GPa) and 23 to 26.0 GPa (average of 23.8 GPa), respectively. This is about 12% increase in average stiffness values of outer lamella near the periosteum as compared with inner regions.
Characterization of Lumbar-Level Spinal Fusion on the Whole Human Spine Under Vibrations
Authors: Lipscomb Kristen , Sarigul-Klijn Nesrin , Klineberg Eric O.
Published: February 2017

In the United States alone, 12–15% of the population will visit their physician for back pain problems each year, creating a direct annual cost of nearly $40 billion. Pain in the spine may be associated with spinal instability and intervertebral disc (IVD) degeneration. The causes of disc degeneration are not completely understood, but have been thought to be linked to excessive loading conditions and whole body vibrations. Patients not responding to non-operative treatment may be considered for surgical fusion.

Vibrations of the spine near its resonant frequency are more likely to lead to spinal injury and subsequent pain. These vibrations may result from prolonged exposure to mechanical vibrations, for example from riding in vehicles. Little is understood about the effect of spine pathologies or treatment techniques on this frequency. While fusion procedure may aid in stabilizing the spine, it may also lead to changes in spine biomechanics. A high fidelity anatomically accurate whole spine finite element model was developed and utilized to examine vibration in the spine using modal analysis. Vibration modes and resonant frequencies were obtained in the healthy spine along with cases of lumbar spine disc degeneration and fusion at several levels, including L4-L5, L3-L5, L5-S, L4-S, and L3-S.
Assessment of the Academic CFD Code Galatea-I With the DLR-F11 Model in High Lift Configuration
Authors: Sarakinos Sotirios S. , Lygidakis Georgios N. , Nikolos Ioannis K.
Published: February 2017

In this study the development and assessment of an academic CFD (Computational Fluid Dynamics) code, named Galatea-I, is reported. The proposed solver employs the RANS (Reynolds-Averaged Navier-Stokes) approach, modified by the artificial compressibility method, along with the SST (Shear Stress Transport) turbulence model to predict steady or unsteady turbulent incompressible flow phenomena on three-dimensional unstructured hybrid grids, composed of prismatic, tetrahedral and pyramidal elements. Parallel processing and an agglomeration multigrid method have been included for the acceleration of the solver’s methodologies. Galatea-I is evaluated against a test case of the HiLiftPW-2 (Second High Lift Prediction Workshop). In particular, the low Mach number flow at 7° incidence angle over the DLR-F11 aircraft configuration of Case 1 of the aforementioned workshop was examined; it considers a three-element wing with a leading edge slat and a trailing edge flap attached on a body pod, without including though any of the support brackets used in the wind tunnel experiments. The obtained results are close to the available experimental data, as well as the numerical results of other reference solvers, indicating the proposed methodology’s potential to predict accurately such low Mach number flows over complex geometries.
Incremental Modeling and Simulation of Mechanical Power Transmission for More Electric Aircraft Flight Control Electromechanical Actuation System Application
Authors: Fu Jian , Maré Jean-Charles , Fu Yongling
Published: February 2017

In the field of more electric aircraft, electromechanical actuators (EMAs) are becoming more and more attractive because of their outstanding benefits of aircraft fuel reduction, maintenance costs saving, and system flexibility improvement. For aerospace electromechanical actuator applications, mechanical power transmission is critical for safety, in which reflected inertia to load, heat generated by energy losses and faults due to jamming, free-play and free-run are specific issues. According to the system-engineering process and simulation-aided design, this communication proposes an incremental approach for the virtual prototyping of EMA mechanical power transmission. Resorting to the Bond-graph formalism, the parasitic effects are progressively introduced and realism of models is increased step-by-step. Finally, the numerical implementations are presented and compared with basic, advanced and full models of mechanical power transmission in AMESim environment. Multi-level submodels are available and can be re-used for preliminary sizing, thermal balance verification and response to fault analysis.
Analysis of Innovative Plasma Actuator Geometries for Boundary Layer Control
Authors: Rodrigues F. F. , Pascoa J. C. , Trancossi M.
Published: February 2017

Active flow control by plasma actuators is a topic of great interest by worldwide scientific community. These devices are mainly used for boundary layer control in order to improve the aerodynamic performance of aerial vehicles. Plasma actuators are simple devices that produces a wall bounded jet which allow to control the adjacent flow without moving mechanical parts. Recently, new geometries have been proposed by different authors in an attempt to improve the performance of these devices. In this work, some of these new configurations will be studied and compared considering its ability for boundary layer control applications. Dielectric Barrier Discharge (DBD) plasma actuator, Plasma Synthetic Jet (PSJ) actuator, Multiple Encapsulated Electrodes (MEE) plasma actuator and Curved plasma actuator (or 3D plasma actuator) will be experimentally studied in this work. Plasma actuators power consumption was measured by two different experimental methods. Results for power consumption and power losses of different plasma actuators geometries were presented and discussed.
Evaluation and Identification of Lean-Green Resourced Person (LGRP) for Integrating and Implementing Lean and Green Practices in a Manufacturing Industry
Authors: Kuppusamy Balaji , Velukkudi Santhanam Senthil Kumar , Bangaru Mohan , Doraiswamy Viswanathan
Published: February 2017

The current manufacturing sector has the objective of maximizing profit by minimizing waste, proper utilization of men, machine and materials. Apart from this, the focus has been on implementing green manufacturing practices in operations. The lean -green topic is an emerging and the new one in the present scenario. The main aim of the green practices is to improve operational activities as well as environmental efficiency. Green practices are concerned with the environmental, social and economic impacts over any organization. Lean manufacturing has been coined by nine wastes. These wastes have an impact on green practices, leading to generation of green wastes. Some of the green waste was excessive resource usage, power usage, pollution, improper health and safety. Lean and green are concurrent manufacturing practices focusing on wastes. The present industrial scenario has been looking into implementing these practices in their operations. A few practices relating to lean-green practices, are integration of lean -green concepts, organization performance analysis, functions, assessment performance and empirical study etc. One of the primary activity of lean-green strategies is showing respect to the workforce. Human factor will be considered as one the main pillars in the lean-green practices. In this research paper a model has been proposed for identification of a Lean-Green Resourced Person (LGRP) for integrating and implementing lean and green practices in a manufacturing industry. Identification of LGRP will help the organization in implementing and executing lean-green strategies into their operations. A multicriteria decision making method has been used for finding the LGRP in the industry. The identification will result in reductions in time consumption during implementation, guiding the industry in a proper way for implementing and integrating the lean-green techniques.
Optimization of Reaming Process Parameters for Titanium Ti-6Al-4V Alloy Using Grey Relational Analysis
Authors: Ahmed L. Shakeel , Kumar M. Pradeep
Published: February 2017

Reaming is one of the finishing processes that have been widely applied in manufacturing industries. Reaming of Titanium Ti-6Al-4V alloy material is an important and current research topic on manufacturing processes. Optimal process parameter setting is an important element in the machinability study of Titanium Ti-6Al-4V alloy. Optimization has most significant importance, particularly for reaming operations. This research work focuses on the multi-response optimization of reaming process parameters using the Taguchi and Grey relational technique to obtain minimum cutting temperature (T), thrust force (Ft), torque (Mt), surface roughness (Ra) and hole quality. The experiments were performed on Titanium Ti-6Al-4V alloy using uncoated carbide straight shank reamer under wet and cryogenic LN2 conditions. Eighteen experimental runs (L18) based on the Taguchi method of orthogonal arrays were performed to determine the best factor level condition. The environment, cutting speed and feed rate were selected as control factors. Grey relational analysis was used to determine the most significant control factors affecting the output parameters. Grey relational grade obtained from the grey relational analysis was used to solve the reaming process with the optimal levels of the multiple performance characteristics responses were established. The optimum results indicate that the reaming results have been improved in wet coolant than the cryogenic LN2 condition.
Potential of Future Thermoelectric Energy Recuperation for Aviation
Authors: Bode Christoph , Friedrichs Jens , Somdalen Ragnar , Köhler Jürgen , Büchter Kai-Daniel , Falter Christoph , Kling Ulrich , Ziolkowski Pawel , Zabrocki Knud , Müller Eckhard , Kožulović Dragan
Published: February 2017

Germanys fifth Aeronautical Research Program (LuFo-V) gives the framework for the TERA-project (Thermoelectric Energy Recuperation for Aviation), which focuses on the positioning of thermoelectricity by means of a holistic reflection of technological possibilities and challenges for the adoption of thermoelectric generators (TEG) to aircraft systems. The aim of this paper is to show the project overview and some first estimations of the performance of an integrated TEG between the hot section of an engine and the cooler bypass flow. Therefore, casing integration positions close to different components are considered such as high pressure turbine, low pressure turbine, nozzle or one of the interducts, where temperature gradients are high enough for efficient TEG function. TEG efficiency is then to be optimized by taking into account occurring thermal resistance, heat transfer mechanisms, efficiency factors, as well as installation and operational system constrains like weight and space.
3D Printing of Gradient Osteochondral Scaffolds Using Soy-Oil Resin
Authors: Nowicki Margaret A. , Plesniak Michael W. , Zhang Lijie Grace
Published: February 2017

Significant challenges exist for replicating osteochondral tissue due to the disparate, gradient nature of natural tissue in this region. The graded transition that exists in this region, moving from subchondral bone to hyaline cartilage at the joint surface, presents unique biological and mechanical challenges for tissue engineering. Past research identified a favorable pore distribution for 3D printed scaffolds. The objective of this research is to use that distribution and further investigate the effects of scaffold material selection and bioactive particle distribution on mechanical, biological, and physiological properties of 3D printed tissue engineered osteochondral scaffolds. Our results indicate that scaffolds constructed with a novel soy-based polymer outperform those constructed with ploy(ethylene glycol)-diacrylate (PEG-DA). This study also indicates that incorporating nanocrystalline hydroxyapatite (nHA) into the soy resin scaffold further improves cellular performance. Additionally, the nHA can be integrated in a controlled fashion to affect only the osteogenic portion of the osteochondral construct.
High-Fidelity One-Dimensional Models for Tapered Structures Analyses
Authors: Viglietti Andrea , Zappino Enrico , Carrera Erasmo
Published: February 2017

This paper presents the static analysis of tapered structures made of composite material using 1D models. These models are based on a one-dimensional formulation derived using the Carrera Unified Formulation (CUF). This formulation allows us to obtain 3D-like results thanks to the use of polynomial expansions to describe the displacement field over the cross-section. According to the types of expansion used, different classes of refined one-dimensional elements are obtained. In this work the Lagrange expansions were used. The use of LE models allows each structural component to bo considered separately; this approach is called component wise (CW). The thin-walled structures are usually made of composite materials, in particular, the aeronautical structures. For this reason, these kinds of structures are taken into account. The stress and displacement fields due to simple load cases have been obtained. The results have been compared with those obtained using commercial tools. The results show the capability of the present refined one-dimensional models to achieve results usually obtained by the use of solid models and therefore, with higher computational cost.
A Component-Wise Approach to Analyse a Composite Launcher Structure Subjected to Loading Factor
Authors: Cavallo Tommaso , Pagani Alfonso , Zappino Enrico , Carrera Erasmo
Published: February 2017

The space structures are realized by combining skin and reinforced components, such as longitudinal reinforcements called stringers and transversal reinforcements called ribs. These reinforced structures allow two main design requirements to be satisfied, the former is the light weight and the latter is a high strength. Solid models (3D) are widely used in the Finite Element Method (FEM) to analyse space structures because they have a high accuracy, in contrast they also have a high number of degrees of freedoms (DOFs) and huge computational costs. For these reasons the one-dimensional models (1D) are gaining success as alternative to 3D models. Classical models, such as Euler-Bernoulli or Timoshenko beam theories, allow the computational cost to be reduced but they are limited by their assumptions. Different refined models have been proposed to overcome these limitations and to extend the use of 1D models to the analysis of complex geometries or advanced materials. In this work very complex space structures are analyzed using 1D model based on the Carrera Unified Formulation (CUF). The free-vibration analysis of isotropic and composite structures are shown. The effects of the loading factor on the natural frequencies of an outline of launcher similar to the Arian V have been investigated. The results highlight the capability of the present refined one-dimensional model to reduce the computational costs without reducing the accuracy of the analysis.
The Effect of Padding Layers Arrangement on Mitigating Head Impacts
Authors: Mansoor-Baghaei Shahab , Sadegh Ali M.
Published: February 2017

In this study the effect of the stiffness sequence of the padding materials of sports equipment, and in particular helmets, on absorbing the impact to the head has been investigated. Specifically, for each arrangement of the padding materials, the strain in the brain has been calculated. In addition, for each impact, the acceleration of the centroid of the head and the Head Injury Criterion (HIC) has also been obtained. As the first preliminary study a simple spherical model of head/brain, including the skull and the brain and three layers of the padding have been generated. The materials of the three layers of padding vary from viscoelastic, soft elastic to a hard elastic material. Then the head was impacted to the padding with the speed of 2 m/s. Finally the sequence of the padding layers was rearranged and the head was impacted to the padding with the same speed. For each case, the HIC value of the impact was determined.

The results revealed that when the viscoelastic materials was in the middle (the first case) the HIC was 143.5 and the strain in the brain at the center corresponding to corpus callosum was 0.192%. Also for, the second case, where the viscoelastic materials was directly the contacting layer with the head, the HIC value was 46.8 and the brain strain was 0.15%. The reason that the strain in corpus callosum has been determined in this analysis is due to the fact that the literature reflects that the strain in corpus callosum is a good predictor for the onset of concussion due to an impact.

It was concluded that when the viscoelastic padding is located on the outer surface of the protective padding device, the HIC value and the strain in the brain are lower, i.e. it is safer. This study can be employed to analyze head impacts with different layered barriers, i.e., composite materials, sandwich panels, glass, and also the interior trim of a car and as well as many other protective paddings.
Three Dimensional Flow Investigation in One and a Half Stage Axial Turbine
Authors: Aziz Imran , Akhtar Imran , Bin Perwez Usama , Ahmed Auwais
Published: February 2017

In this study, three dimensional flow analysis of one and a half stage axial turbine is investigated. The objective of this study is to analyse the effect of rotor stator interaction and the resulting unsteadiness. This includes the effect of first row of Nozzle guide vane (NGV) wakes on rotor blades, secondary vortical flow prediction, influence of rotor wakes on the flow pattern of second stator, appreciation and application of techniques to model the exact blade counts across the rotor-stator interfaces. We employ a three-dimensional finite-volume based solver to simulate the flow in the turbine using SST model to account for turbulence effects. Sliding mesh technique is used to allow the transfer of flow parameters across the sliding rotor/stator interfaces. In order to model a single passage configuration, profile transformation and time transformation method is used. The flow physics for the visualization and understanding of flow behavior in a 3D turbine cascade is explained in detail and validated with the previous experimental and numerical studies. The study provides application of computationally efficient methods for simulating the fluid flow in a turbine which contain unequal number of rotor and stator blades.
A New Trigonometric Higher-Order Shear and Normal Deformation Theory for Functionally Graded Plates
Authors: Gupta Ankit , Talha Mohammad
Published: February 2017

In the present study, a new trigonometric higher-order shear and normal deformation theory is proposed and implemented to investigate the free vibration characteristics of functionally graded material (FGM) plates. The present theory comprises the nonlinear variation in the in-plane and transverse displacement and accommodates, both shear deformation and thickness stretching effects. It also satisfies the stress-free boundary conditions on the top and bottom surfaces of the plate without requiring any shear correction factor. The governing equations are derived using the variational principle. The effective mechanical properties of FGM plates are assumed to vary according to a power law distribution of the volume fraction of the constituents. Poisson’s ratios of FGM plates are assumed constant. The numerical solution has been obtained using an efficient displacement based C0 finite element model with eight degrees of freedom per node. The computed results are compared with 3-dimensional and quasi-3-dimensional solutions and those projected by other well-known plate theories. Natural frequencies of the functionally graded plates with various side-to-thickness ratios, boundary conditions, and volume fraction index ‘n’ have been computed. It can be concluded that the proposed model is not only accurate but also simple in predicting the vibration behavior of functionally graded plates.
Experimental Investigations of a High Frequency Master-Slave Fluidic Oscillator to Achieve Independent Frequency and Mass Flow Characteristics
Authors: Bettrich Valentin , Niehuis Reinhard
Published: February 2017

High frequency fluidic oscillators have been of scientific interest for many decades. Especially over the last couple of years fluidic oscillators became more important for active flow control applications. At the Institute of Jet Propulsion of the University of the German Federal Armed Forces Munich studies on different kinds of flow control methods were carried out on aerodynamically highly loaded low pressure turbine blades. On the basis of these studies, the most efficient way to trigger transition at low Reynolds numbers was found to be with fluidic oscillators at frequencies up to 10 kHz.

Still, it is an open issue whether it is most efficient to trigger Tollmien-Schlichting waves, stimulate Kelvin-Helmholtz instabilities or simply induce a frequency independent disturbance in form of a periodic impulse for boundary layer control on aero-dynamically highly loaded low pressure turbine blades. To find an answer to these questions, a high frequency master-slave fluidic oscillator is introduced with an independent frequency and mass flow characteristic. Any frequency from the master oscillator’s characteristic can be chosen and the mass flow rate can be controlled with the slave oscillator. Contrary to concepts with fast switching valves or piezo actuators, this actuator is based on a working principle without the necessity of any moving and life limited parts.

Based on experimental results, the characteristics of the master as well as the coupled oscillator are shown. The predictable operation of the coupled device is demonstrated in detail for a constant overall mass flow rate at discrete frequencies of 5 and 6 kHz. In addition, it is also shown that the mass flow can be varied with one master-slave arrangement by a factor of six while keeping the frequency constant at 5 or 6 kHz, respectively.

Besides proof of concept these investigations focus on relevant parameters for active boundary layer and transition control. The frequency and velocity spectra of the coupled device are presented for constant frequency and constant mass flow operating points. Based on these results the improvement potential of the coupled oscillator for fundamental research on this topic is discussed.
Cell Response to Cyclic Strain at Focal Adhesions
Authors: Shiraishi Toshihiko , Fukuno Tomohiro
Published: February 2017

Cells are known to sense and respond to mechanical stimulations. The fact shows that there are some cellular mechanosensors for mechanical stimulations. One of the candidates of the mechanosensors is focal adhesions which are large macromolecular assemblies via which mechanical force and regulatory signals may be transmitted between the extracellular matrix and an interacting cell. Although it is quite important to clarify the mechanism of sensing and responding to the mechanical vibration via focal adhesions, there was no micro device applying time-varied mechanical loading to a single focal adhesion of the order of a micrometer. In order to solve the challenging issue, we developed a magnetic micropillar substrate which is able to apply cyclic strain to focal adhesions of a cell. Using the substrate, we investigated how a single osteoblast-like cell changed the direction of migration on micropillars cyclically deflected at 5 Hz and revealed the relationship between the cell migration and the traction force. The experimental results indicate that a cell may sense the cyclic strain and reduce the traction force which is not enough to move the cell body forward leading to changing the migration direction toward the place without cyclic strain.
On Squat Jump Exercise
Authors: Caruntu Dumitru I. , Moreno Ricardo
Published: February 2017

This paper deals with the mechanics of the human leg and forces in the muscles, ligaments, and joint contact in the leg during a squat jump exercise. An inverse dynamics approach is used in this work. A 2-D dynamic model of one limb in the sagittal plane is used to investigate this ballistic task. Results are then compared to data available in the literature. They show good agreement. The response of the ligament forces and the tibio-femoral contact point location during the exercise are reported.
IoT and Self-Driving Cars a Revolution Beyond the Automobile Industry
Authors: Luís-Ferreira Fernando , Ghimire Sudeep , Sarraipa João , Jardim-Goncalves Ricardo
Published: February 2017

Transportation is a sector of activity in permanent change. From airplanes to cars, trains and boats all forms of transportation aim at meeting personal or business needs of displacement of persons and goods. Those needs include safety, reliability, on time with the best effectiveness, and finally, providing the best price. This paper aims at studying car transportation’s consequences regarding last developments that culminate in the self-driving cars. This study analyses the impact of such changes at social and industrial level, considering also the coexistence of traditional cars and self-driving cars in diverse aspects. The authors aim to establish a proficient debate on such important changes for the near future, to create awareness of the potential consequences of such societal and business revolution and generate some conclusions addressing these complex challenges for the years to come. This paper also issues some recommendations for the coexistence of self-driving, autonomous and traditional cars during the transitory period.
Effects of Defects on the Performance of Hierarchical Honeycomb Metamaterials Realized Through Additive Manufacturing
Authors: Rahman Kazi Moshiur , Letcher Todd , Hu Zhong
Published: February 2017

Cellular metamaterials are of immense interest for many current engineering applications. Tailoring the structural organization of cellular structures leads to new metamaterials with superior properties leading to low weight and very strong/stiff materials. Incorporation of hierarchy to regular cellular structures enhances the properties and introduces novel tailorable metamaterials.

For many complex cellular metamaterials, the only realistic manufacturing process is additive manufacturing (AM). The use of AM to manufacture large structures may lead to several types of defects during the manufacturing process, such as missing/broken cell walls, irregular thickness, flawed joints, missing (partial) layers, and irregular elastic plastic behavior due to toolpath. For large structures, it would be beneficial to understand the effect of defects on the overall performance of the structure to determine if the manufacturing defect(s) are significant enough to abort and restart or whether the material can still be used.

Honeycomb structures are used for the high strength to weight ratio applications. These metamaterials have been studied and several models have been developed based on idealized cell structures to explain their elastic plastic behavior. However, these models do not capture real-world manufacturing defects resulting from AM. The variation of elastic plastic behavior of regular honeycomb structures with defects has been studied, but the performance of hierarchical honeycomb structures with defects is still unknown. In this study, the effects of missing cell walls are investigated to understand the elastic behavior of hierarchical honeycomb structures through simulations using finite element analysis. Regular (zero order), first order and second order hierarchical honeycombs have been investigated in this study. The first level of hierarchy has been implemented by changing each three edge vertex of a regular hexagonal honeycomb lattice by adding another smaller hexagon. The second level of hierarchy is created by adding another smaller hexagon at each three edge vertex of the hexagons added for the first order hierarchy. For the hierarchical cases, the overall density of the honeycomb is held constant to the parent structure (zero order or regular) by reducing the thickness of the cell wall in the first and second order structures. ANSYS® was used to develop finite element models to analyze the performance of both perfect and defected regular, first order and second order hierarchical honeycombs. Defects were added to the model by randomly removing cell walls. Hierarchical honeycombs demonstrated more sensitivity to missing cell walls than regular honeycombs. On average, the elastic modulus decreased by 45% with 5.5% missing cell walls for regular honeycombs, 60% with 4% missing cell walls for first order hierarchical honeycomb and 95% with 4% missing cell walls for second order hierarchical honeycombs.
Aquaculture Production Processes and Training Validation Through Serious Games
Authors: Marcelino-Jesus Elsa , Artifice Andreia , Sarraipa Joao , Luís-Ferreira Fernando , Ilie-Zudor Elisabeth , Jardim-Goncalves Ricardo
Published: February 2017

Nowadays, and due to the shortage of wild fish in our seas, rivers and lakes has led to the growth of the aquaculture industry and consequently to the increase of existing aquaculture fish in the markets for domestic consumption to a global scale. In this sense, aquaculture plays a central role to feed the world population in a healthy way and simultaneously for the preservation of the aquatic ecosystems. Thus, the aquaculture production process can be determined by several factors namely biological, technological, economic, and environmental. The authors intend to address and validate such factors related to production processes in the AquaSmart project using serious games. The Serious Games strategy proposes to demonstrate the technological results of the project, namely data analytics tools able to generate new knowledge to improve aquaculture production processes. Additionally, it also intends to work as supporting training and marketing material, validating both the tools and the training programme.
A Framework for Evaluating Pipe Repair Technologies for CuNi Shipboard Piping Systems
Authors: DeGiorgi V. G. , Policastro S. A. , Feng C. R. , Fonda R. W.
Published: February 2017

A shipboard piping system can be considered analogous to the transport and distribution system of a land-based piping system. The intakes and supply pumps provide the initial uptake and head pressure while the piping system provides the distribution throughout the rest of the ship. Piping systems must not degrade or corrode due to the contained fluid but also must endure structural loadings. Interior damage can come in the form of corrosion such as pitting, general wasting away of material due to galvanic corrosion, mechanical deformations due to structural and vibrational loadings. A decision matrix based framework for evaluation using a modified Pugh Controlled Convergence technique was developed for evaluation of metallic coatings under consideration for shipboard system repairs which included mechanical and electrochemical performance characteristics. Candidate coatings for further study and additional testing requirements are identified through the process. The mechanical evaluation focuses on microstructural characterization and mechanical response. The electrochemical evaluation focuses on general corrosion and galvanic interactions between each coating and Cu0.7Ni0.3, a common piping material also often referred to as 70-30 CuNi. The outcome of the evaluation sequence is the ranking of relative merit of coatings. Results are presented which show the wide range of characteristics possible. The extension of the decision matrix to manufacturability issues will also be discussed.
Requirements for the Development of Medical Devices: Caregivers Perspectives Survey
Authors: Bezerra Karolina , Machado José , Leão Celina P. , Soares Filomena , Carvalho Vitor , Matos Demétrio
Published: February 2017

The growth of the elderly population enhances the importance of the quality of the healthcare, which should be administered daily by professionals, whether on a temporary or permanent basis. A core issue to take into account, in this context, is the characterization of these services, especially their adaptation to the specific needs of the bedridden people. In doing so, the quality of life of caregivers, in what concerns facilitating their daily tasks, is also taken into account. A questionnaire was developed to gather information allowing the characterization of both needs and gaps in healthcare identifying the particularities and necessities of the provided services. The questionnaire focuses on three targets: the bedridden characterization, the permanent caregiver and the non-permanent caregiver. The study is descriptive and exploratory, contemplating a quantitative approach. The main objective of the study is to define the important areas worthy of attention, to protect the healthcare of caregivers in the utilization of devices and to be able to build products without structural problems, thus, creating better condition of life and offer solutions in some contexts and tasks, such as, comfort, hygiene and safety.
A Computational Model of Vestibular Fluid Response to Human Body Rotation
Authors: Okeke Marie-Urlima , Smith Sonya T. , Graf Werner
Published: February 2017

A computational model was developed to study the response of vestibular fluid to body motions, relating eye movement to vestibular displacement. The response in the semicircular canals (SCCs) and otolith organs were approximated as a torsional pendulum and a forced wave equation, respectively. The results of the math model were found to be consistent with results found in previous models. The results of the model will also be compared to those found experimentally using VALUS, a rotational platform updated to be used for vestibular testing.
Influence of Intracranial Pressure on the Lamina Cribrosa
Authors: Tong Junfei , Hua Yi , Ghate Deepta , Kedar Sachin , Gu Linxia
Published: February 2017

Glaucoma is an eye disease related with vision field loss. Although previous study has investigated the influence of intraocular pressure (IOP) on the glaucoma damage to the lamina cribrosa (LC), the intracranial pressure’s (ICP) effect on the LC has never been elucidated. The goal of this work is to determine the effect of ICP on the LC.
Understanding the Differences in Hemispherical Dome and Biaxial Test During Equi-Biaxial Tension on Cruciform
Authors: Nikhare Chetan P. , Vorisek Emmett , Nolan John , Roth John T.
Published: February 2017

One metal manufacturing process which uses thousands of processes to trim, stretch, draw, bend etc. under a big umbrella is sheet metal forming. Using heavy equipment, the sheet metal parts are deformed into complex geometries. The complexity in these parts produces multi-axial stress and strain, a state for which it is critical to analyze using conventional tools. Traditionally, the mechanical properties of materials have been characterized using the uniaxial tension test. This test is considered adequate for simple forming operations where single axis loading is dominant. Previous studies, however, have noted that the data acquired from this type of testing is not enough and additional details in other axes under simultaneous deformation conditions are important. To analyze the biaxial strain, some studies have suggested using the limiting dome height test and bulge test. However, these tests limit the extent of using multi-axial loading and the resulting stress pattern due to contact surfaces. Therefore, researchers devised the biaxial machine which is designed specifically to provide biaxial stress components using multiple and varying loading conditions.

The idea of this work is to evaluate the relationship between the dome test data and the biaxial test data. For this comparison, cruciform specimens with a diamond shaped thinner gage in the center were deformed with biaxial stretching on the biaxial testing machine. In addition, the cruciform specimens were bi-axially stretched with a hemispherical punch in a conventional die-punch setting. Furthermore, in each case, the process was simulated using a 3D model generated on ABAQUS. These models were then compared with the experimental results. The forces on each arm, strain path, forming and formability was analyzed. The differences between the processes were detailed. It was found that biaxial tests eliminated the pressurization effect which could be found in hemispherical dome tests.