bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Instrumentation of an Experimental Test-Bed for Research in Energy Efficiency in Buildings
Authors: Baghdasarian Arsine , Ramos Omar , Ruvalcaba Jesse , Talome Sergio , Wang Frank , Sabatier Lambert , Pacheco-Vega Arturo
Published: March 2016

This paper reports on the development of a conceptual design, construction and instrumentation of an experimental facility that can be used to carry out experimental research towards increasing energy efficiency in buildings. The overarching idea is to construct a system that emulates the scaled dimensions and materials of a typical building structure. The sub-scale testbed consists of a two-floor building configuration with dimensions of 1.2 m × 0.92 m × 1.1 m. The building structure is made out of wood, and covered with drywall and fiberglass insulation. Fixed walls are selected for the first floor whereas movable walls are incorporated into the second floor to study the effects of different room configurations. Four staircase openings enable airflow between the two floors. The second floor has a tiled-style ceiling and removable walls that allow for connectivity of sensors and actuators. A set of heating and cooling sub-systems, consisting of light bulbs and thermoelectric coolers connected to fans, are used for each room in the building. Both the set of light bulbs as well as the cooling system are powered through a relay box, and connected to a computer via LabVIEW which also interfaces the different sensing and actuating devices. The capabilities of the experimental facility are tested by implementing time-dependent heating- and cooling-processes and an on-off control strategy on a two-room prototype. Preliminary results demonstrate that the experimental testbed offers a reliable and versatile experimental system for research purposes.
Enhanced Dielectric Performance of Nano Boron Nitride Impregnated Cellulosic Insulations
Authors: Taha Jaime , Narayanan T. N. , Ajayan P. M. , Contreras Jose E. , Rodriguez Josue
Published: March 2016

The application of nanodielectric materials in high voltage power transmission systems has received particular attention. This investigation shows a comparison of the AC dielectric behavior of insulating paper impregnated with conventional mineral oil and dielectric nanofluids. The AC breakdown voltages of various systems were measured according to ASTM D149 to determine the effect of using nanofluids as dielectric media. The observed results indicate that addition of insulating nanoparticles to conventional transformer oil exhibits substantially higher AC breakdown voltage than that of pure mineral oil impregnated paper.
Numerical Analysis of Effect of Cohesive Parameters on Mixed-Mode Failure of Double-Scarf Adhesive Joint Subjected to Uniaxial Tensile Loadings
Authors: Liao Lijuan , Huang Chenguang
Published: March 2016

In the present study, the effects of cohesive parameters on the mixed-mode failure of double-scarf adhesive joint (DSAJ) subjected to uniaxial tensile loadings were examined and discussed numerically. For DSAJ with no perpendicular or parallel with the external loading direction, complex stress state (mixture of tensile and shear stresses) occurs at the adhesive interface. In addition, adhesive joint failure, which is a gradually process rather than a sudden transition, is accompanied by energy dissipates gradually at the crack tip. Correspondingly, cohesive zone model (CZM) coupled with finite element method (FEM) was implemented to verify the mechanism of crack from initiation to the complete failure. As the constitutive relation of the adhesive layer, the traction-separation (T-S) law determines the interface damage evolution. Additionally, the shape of T-S curves in mode I and mode II are crucially decided by the cohesive strengths and critical fracture energies in each mode, respectively. Firstly, the non-dimensional-normalized form of ultimate tensile loading of DSAJ was obtained using dimensional analysis. Then, three cases of cohesive parameters (case of constant anisotropy extent & case of constant critical fracture energy in each mode & case of constant cohesive strength in each mode) according to the non-dimensional-normalized form of adhesive properties were designed. Two types adhesives (brittle and ductile) were chosen to examine the effects of adhesive properties on the failure of DSAJ in this study. To avoid the influence of the geometries on DSAJ mechanical behaviors, the thickness of the adhesive layer and the scarf angle θ were held constantly, respectively. In numerical calculations, the change trends of the ultimate tensile loading (Fu), the failure energy (Ef) and the damage level (D) corresponding to Fu with respect to the cohesive parameters were discussed. It can be observed the cohesive strengths in mode I and mode II codetermine Fu of DSAJ with unequal rates. Moreover, Ef of DSAJ, which is the necessary energy for the joint failure, is governed by the critical fracture energies in mode I and mode II with different contributions. Besides, it also obtained that the evolutions of D corresponding to Fu of DSAJ with brittle and ductile adhesives are certain different. Generally, D of DSAJ with brittle adhesive is higher and more uneven than that of DSAJ with ductile adhesive. Accordingly, it can be concluded that DSAJ with brittle adhesive has lower ability to distribute the loading over a smaller cohesive zone with less uniform distribution. In addition, the numerical results revealed that with the increment of ratio in each case set in this paper, D of DSAJ does not rise obviously.
Two-Dimensional Linear Friction Damper Consisting of Concave Cone and Cylindrical Member (Investigation of Performance by Numerical Simulation and Experiment)
Authors: Yamaguchi Hideya , Yoshida Hidehisa
Published: March 2016

A passive vibration isolation system consisting of a constant friction force has performance limitations; the isolation performance declines and the residual displacement becomes large in the case of the large friction force, while the resonant peak becomes large in the case of the small friction force. It is known that above drawbacks are avoidable when the friction force varies in proportion to the relative displacement. Recently, authors have proposed a simple linear friction damper mechanism that consists of a cylindrical block and a tilt lever supported with a pivot or a leaf spring. Performance of the vibration isolation system equipped with the proposed damper is investigated, and its effectiveness is confirmed by numerical simulations and the experiments. However, the motion of the mechanism is limited to one-dimension. This paper proposes an extended mechanism that can be applied to motion moving in two dimensions by combining the concave cone and the cylindrical member. The concave cone is supported with a universal joint on the apex side and its tilting motion is constrained by the restoring spring. The rounded edge of the cylindrical member is set up to contact the inside flank of the concave cone. When the cylindrical member moves in an arbitrary direction on the planar floor and pushes the concave cone, the normal and friction forces at the contact point vary depending on the displacement of the cylindrical member. The fundamental property and the performance of the proposed mechanism are investigated by numerical simulations and experiments.
Analysis of Gas Hydrate Formation in Subsea External Sleeve Choke
Authors: Hu Biao , Zhu Hongwu , Xu Fangling , Zhang Youjiang , Lv Huiqin , Yin Binbin
Published: March 2016

Gas hydrates are well-known challenge for subsea gas production and transportation, since the hydrates can plug subsea production equipments with potential risks for safety, environment and economic. In the present paper, combining CFD technology with temperature-pressure curve of natural gas hydrate forming, the hydrate formation in subsea external sleeve choke is studied. The difference between real pressure in the choke and critical pressure of gas hydrate formation is defined as equivalent pressure, based on which a new approach to predict gas hydrate formation called Maximum Equivalent Pressure Method is proposed, and the influence of inlet temperature, outlet pressure and relative opening to the maximum equivalent pressure are investigated. The critical relative opening ranges of gas hydrate formation under conditions of certain inlet temperature and outlet pressure are obtained. In case that the relative opening is within the critical range, there would be no hydrate formation in the choke, otherwise it would generate hydrate.
The Flow Behavior of a Confined Viscoplastic Annular Jet
Authors: Hammad Khaled J.
Published: March 2016

Flow characteristics of a confined annular jet of a viscoplastic non-Newtonian fluid were investigated numerically within the steady laminar flow regime. A parametric study is implemented to investigate the influence of confinement ratio, CR, inner-to-outer annular nozzle diameter ratio, k, and yield number, Y, over the following range of parameters: CR = {5, 40}, k = {0, 0.5, 0.8}, and Y = {0, 0.5, 1}. Central and outer recirculation regions typically characterize the flow of a confined Newtonian annular jet. However, extent of the outer recirculation region and recirculation intensities of both the central and outer regions were found to substantially diminish with the yield number for all confinement and annular diameter ratios, resulting in the elimination of recirculation throughout the whole flow field at high yield numbers. The confinement ratio has a dramatic impact on the recirculation intensity of the outer region, and centerline velocity and jet momentum evolution, only in the case of Newtonian flows. Axial penetration of the submerged annular jet decreases with the inner-to-outer annular nozzle diameter ratio and the yield numbers for all confinement ratios.
Single Machine Infinite Bus Power System Control With Resilient Extended Kalman Filter
Authors: Gu Patrick , Wang Xin
Published: March 2016

The Extended Kalman Filter is commonly used as a non-linear estimator for engineering practices. However, the Extended Kalman Filter’s performance degrades or may even become unstable when the measurement data becomes inaccurate through random measurement failures, which is a widespread problem in many data-intensive control applications. To address this issue, the paper proposes an improved Extended Kalman Filter which is resilient against sensor failures. This work focuses on the Resilient Extended Kalman Filter’s derivation with its application to the single generator infinite bus power system. The sensor failure rate is modeled as a Binomial distribution with a known mean value. The performance of the proposed Resilient Extended Kalman Filter is compared with the traditional Extended Kalman Filter under various chances of sensor failures.
Numerical Simulation of Fluid Flow in Three Dimensional Domain Based on Two Stage Pressure-Velocity Correction Method
Authors: Sabir Osama , Tuan Ya T. M. Y. S.
Published: March 2016

In this paper a two stage pressure-velocity correction approach for immersed boundary method is proposed. The model is illustrated the interaction between incompressible viscous fluid and immersed bodies in three dimensional domain. A second correction step is added to the pressure value and the velocity vectors using Simplified Marker and Cell method (SMAC). This new scheme is applied on staggered grid using implicit finite difference methods in order to achieve second order accuracy. The algorithm is validated in comparison with a bench mark fluid solid structure case of laminar flow around a cylinder. The drag and lift coefficients are chosen to be the fundamental element to authenticate the new algorithm. Adding new stage of second pressure corrections did not affect the computations cost comparing with single correction stage methods. The preliminary results show there is a strong statistical correlation between Reynolds number and the error in pressure values. The stability of the developing method remain at the same level with other immersed boundary methods. Associated with conventional numerical optimization methods, the proposed approach achieve an acceptable degree of convergence rate per iteration and confirm decent performance.
Multi Response Optimization of Submerged Friction Stir Welding Process Parameters Using TOPSIS Approach
Authors: Velukkudi Santhanam Senthil Kumar , Rathinaraj Lokesh , Chandran Rathinasuriyan , Ramaiyan Shankar
Published: March 2016

Friction stir welding (FSW) is a solid-state welding process which is used to join high-strength aircraft aluminum alloys and other metallic alloys which are difficult to weld by conventional fusion welding. In this paper, AA6063-O alloy of 6mm thickness was taken and friction stir welded under the water in order to improve the joint properties. The process parameters considered as rotational speed, welding speed and tool pin profiles (cylindrical, threaded and tapered) are optimized with multi response characteristics including hardness, tensile strength and % elongation. In order to solve a multi response optimization problem, the traditional Taguchi approach is insufficient. To overcome this constraint, a multi criteria decision making approach, namely, techniques for order preference by similarity to ideal solution (TOPSIS) is applied in the present study [13]. The optimal result indicates that the multi response characteristics of the AA6063-O during the submerged friction stir welding process can be enhanced through the TOPSIS approach. The Analysis of Variance (ANOVA) was carried out to investigate the significant parameter for the submerged friction stir welding process. The mechanical properties of the submerged FSW are compared with normal FSW joints.
Dry Deep Drilling of Titanium Aluminide
Authors: Tom Mathew Nithin , Vijayaraghavan L.
Published: March 2016

Intermetallic titanium aluminides are recognized as the possibly alloys for high performance aerospace and automobile application. There is an increasing interest of this material due to their extraordinary material properties. The understanding of the machinability of titanium aluminides during various metal cutting processes is very much essential for its wide acceptance over various fields of application. Drilling, with high aspect ratio is a key machining area to be explored because of its complex nature. In the present work, holes were drilled on a titanium aluminide intermetallic alloy with an aspect ratio of 9.37, focusing on the machinability under dry environment using coated and uncoated twist drill. Machinability investigations were evaluated based on the, thrust force, torque, surface integrity, chip morphology, burr formation and performance of the tool. From the results of thrust force and torque, it is revealed that the coated tool doesn’t show any significant advantages over the uncoated tool. The variation of chip shapes was observed as the depth progresses. Small ring shape, uniform and non-uniform roll back burr were observed as the cutting parameters are varied. The adherence of workpiece material on to the tool and various surface defects were observed under all cutting conditions.
A Novel Sin-Hyperbolic Creep Damage Model to Overcome the Mesh Dependency of Classic Local Approach Kachanov-Rabotnov Model
Authors: Haque Mohammad Shafinul , Stewart Calvin Maurice
Published: March 2016

All materials include defects or voids. Under load, these defects can serve as a nucleus of crack initiation and propagation. Numerical analysis of notched specimen can provide prediction of creep damage or crack propagation of materials containing defects or initial cracks. However, FEM analyses using the local CDM approach exhibits mesh size dependency, and exhibits localized damaged zone around the crack. In this study, a novel Sin-hyperbolic (Sinh) model is demonstrated to significantly mitigate mesh dependency and exhibits a nonlocal damage distribution around the crack when compared to the classical Kachanov-Rabotnov model. Finite element analysis of circular notched specimen of 304 Stainless-Steel (SS) is performed. Contour plots of damage evolution, and mesh dependency of crack growth rate are discussed in detail. It is demonstrated that the Sinh model offers better creep damage, and crack growth analysis and significantly improves the stress sensitivity, damage localization, and mesh-dependency of numerical results.
On Boundary Damping for Semi-Infinite Strings and Beams
Authors: Akkaya Tugce , van Horssen Wim T.
Published: March 2016

In this paper, initial boundary value problems for a linear string and beam equation are considered. The main aim is to study the reflection of an incident wave at the boundary and the damping properties for different types of boundary conditions such as a mass-spring-dashpot for semi-infinite strings, and pinned, sliding, clamped and damping boundary conditions for semi-infinite beams. The system of transverse vibrations are divided into model 1 and model 2 which are described as a string problem and beam problem, respectively. In order to construct explicit solutions of the boundary value problem for the first model the D’Alembert method will be used to the one dimensional wave equation on the semi-infinite domain, and for the second model the method of Laplace transforms will be applied to a beam equation on a semi-infinite domain. It will be shown how waves are damped and reflected for different types of boundaries and how much energy is dissipated at the boundary.
A Pilot Study of Cognitive-Neuroscience Mechanism in Product Concept Evaluation
Authors: Takai Shun , Wagner Michael , Esterman Marcos
Published: March 2016

Novel, functional, and aesthetic products are thought to have a high likelihood of success in the marketplace. While making sound design decisions is a critical ability of good designers, evaluating product concepts for their future successes in the marketplace is a challenging task. In design classes, only about half of product concepts selected by student design teams may be retained and prototyped into final products, i.e., about half of student design teams find that their initial product concepts are difficult to make workable and change to different concepts by the time they create prototypes for testing. This paper investigates if electrophysiological concomitants in product concept evaluation may potentially be used to improve students’ and designers’ product concept evaluation processes. The preliminary data in this pilot study indicate that distinct decision-making processes may occur during evaluations of product concepts on novelty, functionality, and aesthetics, evidenced by brain activation differences among students.
Some Problems of Statistical Modeling of Intermittent Turbulent Flows and Their Solutions
Authors: Nuzhnov Yu. V.
Published: March 2016

Some problems of statistical modeling of turbulent flows associated with the hydrodynamic effects of intermittency of various dynamic and scalar fields are identified, and a justification of their solutions is proposed.

At first examines some problems of statistical modeling of large-scale (energy-containing) turbulence structure under the conditions of turbulent and nonturbulent fluid intermittency in the turbulent flow. This primarily applies to the problem of obtaining the differential equations of hydrodynamics for conditional statistical moments (conditional averages), i.e. for single-point statistical moments of each of the intermittent media of turbulent flow. To solve this problem is given a mathematically rigorous justification of conducting the operation of conditional averaging of the Navier-Stokes equations. As a result was obtained the system of differential equations for the conditional averages of turbulent and nonturbulent fluid. The main advantage of the obtained differential equations for the conditional averages is that these equations don’t contain the source terms. Therewith is given a physical substantiation of transformation process of nonturbulent fluid in turbulent, that occurs in a thin superlayer, which separates turbulent and nonturbulent fluid. Here also is given a justification of conducting the operation of total averaging of the partial derivates, which, as it turns out, is not a permutational and leads to a number of specific features in comparison with the unconditional averaging in RANS.

Another problem associated with statistical modeling of inhomogeneous turbulent flows, i.e. flows with an inhomogeneous field of scalar substance. It is known that the dynamic field with turbulent fluid does not coincide with the inhomogeneous field of scalar substance. To solve this problem is proposed a method of calculating the statistical characteristics both of the turbulent fluid and the inhomogeneous field of a passive admixture concentration. It is shown, that the conditional averages of the passive admixture concentration are significantly different.

In conclusion we consider the problem of statistical modeling of diffusional turbulent combustion of not pre-mixed chemically reacting gases, expressly the modeling by the known method PDF with involving the “reduced fuel concentration” as the passive impurity concentration. To solve this problem is given a justification of new differential equations, allowing to carry out calculations only of the conditional averages for the intersection region of the dynamic field of the turbulent fluid and the inhomogeneous field of the passive impurity concentration. Some results of such calculations, performed in the self-similar field of diffusion turbulent propane plume, are presented together with the experimental data available in literature.
Locomotive Underactuated Implement Guided via Elastic Elements (L.U.I.G.E.E): A Preliminary Design
Authors: Reilly Thomas , O’Rourke Jerome K. , Steudler Daniel , Piovesan Davide , Bortoletto Roberto
Published: March 2016

This paper presents the simulation and fabrication of a bipedal humanoid system actuated with linear springs to produce a standing equilibrium position.

The humanoid system is comprised of two leg assemblies connected by a hip bracket. Eleven pairs of springs were attached to the system in locations designed to simulate the muscles and tendons in a human body. The assembly was modeled in the multi-body dynamics simulation software SimWise 4D. Simulations were performed to determine the springs’ stiffness and natural lengths using a top-down heuristic approach. After a set of springs were found to produce a good simulated stable position, they were cross referenced to standard commercially-available parts. A final simulation was then performed to verify that the real-world spring values produced a stable system.

Working in tandem with SimWise 4D, the humanoid assembly was fabricated using PLA plastic via an extrusion-type rapid prototyping machine. From the results of the simulation, the set of working springs were implemented onto the plastic model. After final modifications, the assembly then produced a standing equilibrium position. Finally, the assembly was perturbed in several directions to ensure that after the system experienced a displacement it would then return to its original position.
An Electrochemical Model Based Optimal Charging Algorithm for Lithium-Ion Batteries
Authors: Pramanik Sourav , Anwar Sohel
Published: March 2016

In recent years, Lithium-Ion battery has gathered lot of importance in many forms of energy storage applications due to its overwhelming benefits. Any battery pack alone cannot achieve its optimal performance unless there is a robust and efficient energy management system, commonly known as battery management system or BMS. The Lithium-Ion charger is a voltage-limiting device that is similar to the lead acid system. The difference lies in a higher cell voltage; tighter voltage tolerance and the absence of trickle or float charge at full charge.

In this work, we propose the design of a novel optimal strategy for charging the battery that better suits the battery performance. A performance index is defined that aims at minimizing the effort of regeneration along with a minimum deviation from the rated maximum thresholds for cell temperature and charging current. A more realistic model based on battery electrochemistry is used for the optimal algorithm design as opposed to equivalent circuit models. To solve the optimization problem, Pontryagin’s principle is used which is very effective for constrained optimization problems with both state and input constraints.

Simulation results show that the proposed optimal charging algorithm is capable of shortening the charging time of a Lithium Ion cell while maintaining the temperature constraint when compared with the standard constant current charging.
Analytical Model of Thin-Film Silicon Solar Cell
Authors: Sharma Ashish , Zivanovic Sandra , Animilli Shravan R. , Genov Dentcho A.
Published: March 2016

There is an important need for improvement in both cost and efficiency of photovoltaic cells. For improved efficiency a better understanding of solar cell performance is required. In this paper we propose an analytical kinetic model of thin-film silicon solar cell, which can provide an intuitive understanding of the effect of illumination on its charge carriers and electric current. The separate cases of homogeneous and inhomogeneous charge carrier generation rates across the device are investigated. Our model also provides for the study of the carrier transport within the quasi-neutral and depletion zones of the device, which is of importance for thin-film solar cells. Two boundary conditions based on (i) fixed surface recombination velocity at the electrodes and (ii) intrinsic conditions for large size devices are explored. The device short circuit current and open circuit voltage are found to increase with the decrease of surface recombination velocity at electrodes. The power conversion efficiency of thin film solar cells is observed to strongly depend on impurity doping concentrations. The developed analytical kinetic model can be used to optimize the design and performance of thin-film solar cells without involving highly complicating numerical codes to solve the corresponding drift-diffusion equations.
A Flexible Manufacturing System Architecture for On-Demand, Rate-Independent Production
Authors: Das Aditya N. , Torres Nahum A. , Popa Dan O.
Published: March 2016

For low to medium production volumes or products with short life cycle, dedicated manufacturing lines often end up being a commercial burden. The high initial non-recurring expenses of the manufacturing infrastructure are eventually passed onto the cost of the product, limiting its commercialization potential. In such cases, flexible frameworks for manufacturing are ideal, at least in theory, with reusability of the same hardware for different product developments. From an implementation standpoint, however, flexible manufacturing platforms are difficult to deploy as they suffer from inherent uncertainties that severely constrains the overall precision in task execution. Low cost flexible robotic manipulation systems, configured using individual modules from an assortment of positioners, often lack the precision required for assemblies with stringent tolerance budgets and therefore have to rely on expensive feedback systems for reliability at the trade-off of process throughput. In order to overcome this fundamental challenge with flexible or modular assembly and packaging systems, this paper presents a novel precision evaluation and control technique. The proposed solution estimates and tracks the end-effector position errors in a robotic manipulation system resulting from the kinematic configuration as well as the dynamic parameters for each specific task; thereby, allowing the automation application to compensate for these errors in run-time. The computation does not require active feedback, thus ensures high throughput while maintaining high reliability. The experimental results provided in this paper demonstrate the efficacy of the proposed approach in the case of a high precision micromanipulation task using a custom robotic manipulation system. The analysis also demonstrates that different system configurations offer different levels of precision metrics.
Concurrent Speed and Position Tracking of PM Brushed DC Motors
Authors: Wang Xin , Suh C. Steve
Published: March 2016

Permanent magnet brushed DC motors are essential components in a wide range of applications in which their unique benefits are explored. However, being sensitive to system based uncertainties such as external loading variation and sudden speed change has made improving the precise control of their speed and position a challenging task. To mitigate such negative effects that invariably undermine motor stability and controllability, a novel wavelet-based nonlinear time-frequency control scheme viable for the concurrent speed and position tracking of permanent magnet brushed DC motor is developed. The control approach has its foundation established in the wavelet-domain adaptive theory which allows control to be exerted in both the time and frequency domains simultaneously. Simulation results demonstrate that the proposed controller is superior to the traditional PID control in mitigating the speed and position responses of a permanent magnet brushed DC motor under severe system uncertainties.
Quantitative Analysis and Improvement of Countersink Depth in Stack Drilling
Authors: Ma Xinguo , Wu Dan , Nan Chenggen , Gao Yuhao
Published: March 2016

While bolt fastening is the most commonly used method for fastening components, hole quality is an important technology standard in modern manufacturing, especially in the aircraft industry. With low stiffness, the machining deformation of aerospace structures has been a striking problem, which makes it difficult to achieve tight tolerance of countersink depth in one-shot drilling of stacked materials. As a result of the manufacturing errors between the workpieces and the digital models, the position of the workpiece surface can hardly be known before drilling. Moreover, the cutting force adds to the deformation of the thin-walled workpiece in the direction of the feed axis. In view of problems mentioned above, a method of position compensation based on the clamp foot displacement is proposed in the paper, which ensures the countersink depth accuracy by compensating for the deformations of clamping and countersinking respectively in different stages of drilling. Some drilling experiments were conducted, in which the forces in the feed direction were real-time monitored and recorded for FEM simulation. The influencing factors of countersink depth error are firstly discussed in this study, which mainly consists of the size of clamping force and the stiffness differences of variable drilling positions. Numerical simulations were carried out to study the deformation characteristics of workpiece under the combining effect of clamping force and cutting force achieved above. Comparing the simulation results and the experiment results, some other influencing factors of countersink depth are discussed.
Tactile Eye Pressure Measurement Through the Eyelid
Authors: Enikov Eniko T. , Polyvás Péter P. , Peyman Gholam , Mccafferty Sean
Published: March 2016

This article presents the early results from a 10-person human subject study evaluating the accuracy of a novel method of indirect estimation of intraocular pressure using tactile sensors. Manual digital palpation tonometery is an old method used to estimate the eye pressure through palpation with ones fingers. Based on this concept, we present an instrumented measurement method, where multiple tactile stiffness sensors are used to infer the intraocular pressure of the eye. The method is validated using experimental data gathered from human subjects with eye pressures from 15 to 22 mmHg and determined by Goldman applanation tonometry (GAT). Bland-Altman plots comparing the GAT measurements and the proposed through-the-eye-lid tonometry indicate a statistical error of 5.16 mmHg, within the 95% confidence interval, which compares favorably with the FDA-mandated error bound of 5 mmHg. Details on the unit operation and data filtering are also presented. Due to its indirect and non-invasive nature, the proposed new tactile tonometry method can be applied at home as a self-administered home tonometer for management of glaucoma.
Engineering Innovation in Biomedical Nanotechnology
Authors: Enikov Eniko T. , Szabó Zoltán , Anton Rein , Skoch Jesse , Sheen Whitney
Published: March 2016

The objective of this National Science Foundation (NSF)-funded undergraduate engineering training project is to introduce nanoscale science and engineering through an innovative use of a technical elective sophomore-level mechatronics course, followed by an Accreditation Board for Engineering and Technology (ABET)-mandated senior-level engineering capstone design project. A unique partnership between University of Arizona’s department of surgery, its neurosurgical division, and the College of Engineering presents a creative environment, where medical residents serve as mentors for undergraduate engineering students in developing product ideas enabled by nanotechnology. Examples include: a smart ventricular peritoneal (VP) shunt with flow-sensing; a bio-resorbable inflatable stent for drug delivery, and a hand-held non-invasive eye tonometer. Results from the first year of the student projects, as well as qualitative assessment of their experience, is presented. Several institutional challenges were also identified.
An Accurate Discrete Model for the Dynamics of Web-Core Sandwich Plates
Authors: Pydah Anup
Published: March 2016

An accurate discrete model is presented here for the dynamics of simply supported web-core sandwich plates using the elasticity approach. By modelling the face-plates as 3D solids and the core webs using a plane stress idealization for transverse bending and classical one-dimensional models for lateral bending and torsion, the non-classical effects of transverse shear deformation, thickness-stretch and rotary inertia are completely accounted for in both, the face-plates and webs. Vibrational frequency results obtained using this model are used to highlight the errors of the commonly used model based on the classical Kirchhoff hypothesis for the face-plates, indicating the importance of using refined theories for modelling the face-plates.
Nonlinear Damping on Large-Amplitude Vibrations of Plates
Authors: Ferrari Giovanni , Amabili Marco , Balasubramanian Prabakaran
Published: March 2016

Large-amplitude (geometrically nonlinear) forced vibrations of completely free sandwich and steel rectangular plates are investigated experimentally. Harmonic excitation is applied by using an electro-dynamic exciter and the plate vibration is measured by using laser Doppler vibrometers. A scanning laser Doppler vibrometer is used for experimental modal analysis since it provides non-contact vibration measurements with very high spatial resolution. The large-amplitude vibration experiments are carried out by using a single point Laser Doppler Vibrometer and a stepped-sine testing procedure. The non-linear frequency response curves are obtained by increasing and decreasing the excitation frequency in very small steps at specific force amplitudes controlled in a closed-loop. The experimental results are compared to numerical simulations obtained by reduced-order models and show very good agreement. The nonlinear damping is experimentally obtained as a function of the vibration amplitude.
Vertical Impact Simulations of a Full-Size and Simplified Scaled Models of an Aircraft Fuselage Section
Authors: Krishna Prasad V. , Tay Y. Y. , Lankarani H. M.
Published: March 2016

Computer modeling and simulations on the crashworthiness of aircraft using validated models have provided insight into the energy-absorption characteristics of structures and have allowed parametric studies in the evaluation of different crash energy management designs. In this study, the dynamic responses of a detailed and simplified full-size, and scaled fuselage models in vertical impact are investigated. The detailed full-size model, constructed from a Boeing 737 mid-fuselage section, consists of a stiff auxiliary fuel tank and a cargo door. The detailed full-size model is dropped from a height of 4.26 m (14 ft) onto a rigid surface, which corresponds to a vertical impact speed of 9.14 m/s (30 ft/s). The drop simulations are performed using the non-linear explicit code, LS-DYNA. Correlation of the detailed full-size model with the physical test conducted by the Federal Aviation Administration is demonstrated. Scale modeling technique applied to the aircraft fuselage section is utilized and for scaling purposes, a simplified full-size model is constructed without the auxiliary fuel tank and cargo door. The crash responses of the simplified full-size models in relation to the detailed full-size model are shown and discussed. The scaling approach involves geometrical scaling of the simplified full-size model with scale factors of 1/5th, 1/10th and 1/20th. The vertical impact simulations of the scaled models are carried with identical impact speed as that of the detailed full-size model. General scaling laws for geometry, mass, velocity, acceleration and forces are utilized to predict the results for the scaled models. The approach and results presented in this study have demonstrated an efficient and innovative method on the design and crashworthiness of a fuselage section.
Lumbar Load Estimation for a MADYMO FAA Hybrid-III Scalable Dummy
Authors: Tay Y. Y. , Cai Y. , Lankarani H. M.
Published: March 2016

The Federal Aviation Administration (FAA) has a number of regulations aimed at protecting occupants in the event of a crash. The Code of Federal Regulations, 14 CFR 25.562, describes the compliance regulation for transport category aircraft, with similar regulations for other types of aircraft in Parts 23, 27 and 29. One of the required tests is the dynamic impact with a Hybrid-II or a FAA Hybrid-III 50th percentile dummy seated on a 60-degree pitched seat, with an input deceleration/acceleration pulse acting primarily on the mid-sagittal plane of the dummy. In particular, an important compliance criterion is that the lumbar/pelvic load must be below the 1,500 lb (6,672 N) compliance limit. The objective of this study is to develop a reasonable approach to estimate the lumbar load tolerance for potential future expansion of lumbar load regulations for other dummy sizes such as an FAA Hybrid-III 5th and 95th percentile dummy. To accomplish this, the lumbar load measured with the Hybrid-II and the FAA Hybrid-III 50th percentile dummy when subjected to the 19 g rigid seat impact tests and simulations are correlated and discussed. The FAA Hybrid-III 50th percentile dummy is then scaled to the 5th and 95th percentile sizes based on GEBOD database. The dynamic behavior of the scaled FAA dummies in the 19 g sled simulation using an ideal acceleration pulse is then simulated and their corresponding lumbar loads are estimated. The dummy models utilized are obtained from the MADYMO crash test dummy database and the dynamic impact simulations are solved using the non-linear multibody dynamic solver, MADYMO. This study proposes the lumbar load tolerances for the 5th and 95th percentile sizes represented by the scaled FAA dummies by correlating their lumbar loads to the Dynamic Response Index (DRI) values. In this study, the lumbar load tolerance values for the 5th and 95th percentiles are proposed to be 870.4 lb (3,871.7 N) and 1772.9 lb (7,886.3 N), respectively. A comparison of the lumbar load tolerances proposed from this study and other sources is also presented.
A Protective Safety Footwear Device Simulation and Design: An Innovative and Healthy Hybrid Component
Authors: Vieira da Silva Joel , Costa Sergio L. , Abreu Maria José , Mendonca Joao P.
Published: March 2016

The use of Personal Protective Equipment (PPE) has become a necessity in view of the number of accidents at work that occurred in the past years. The European Community (EU) and the member states are creating strategies aiming the increase of the use of PPE’s and consequently the decrease of the number of the accidents at work, decreasing also the number of injuries caused by them and their severity. In this paper, a brief review of safety footwear and its components will be presented focusing on penetration resistant inserts. Additionally, we present a project in development at University of Minho that aims to improve the existent shoes. This project proposes a brand new penetration resistant inserts through a combination of innovative materials.
Research on Edge Cracks of the Ring Part During Ring Rolling Based on Cast Blank
Authors: Qi Huiping , Li Yongtang , Wei Xiaojian , Ju Li , Qian Dongsheng
Published: March 2016

The casting-rolling compound forming process is a new process to produce seamless ring shaped components. In the new process, the input blank for the new process is a ring shaped casting blank. Edge crack affects severely the quality of rolled ring parts in ring rolling process based on cast blank. Theoretical analysis, numerical simulation and experiments were combined to study the edge crack and its prevention methods during ring rolling. Conclusions are obtained that: (1) for casting blank, the initial stage of ring rolling is crucial to prevent the initiation and propagation of the edge cracks. (2) in the ring rolling process, the occurrence of cracks were influenced mainly by rolling temperature and feed speed of the core-roller. Cracks could be avoided by controlling above two rolling parameters. (3) in the initial stage of ring rolling, higher rolling temperature and lower feed speed of the core-roller are beneficial to improve the plasticity of the materials and restrain effectively the initiation and propagation of cracks. The work is a part of the research of the new casting-rolling compound forming process. It will promote the development of the new process.
Development of Adaptable Light Weighting Methods for Material Extrusion Processes
Authors: Urbanic Ruth Jill , DiCecco Liza
Published: March 2016

The material extrusion family of additive manufacturing processes, such as the fused deposition modelling (FDM) process, can be very expensive for component fabrication due to the long production times for large, thick walled, complex components, and the material costs. Introducing light weighting strategies could balance the required strength and material usage. As the material extrusion processes exhibit anisotropic mechanical characteristics, physical experimentation is required to calibrate simulation models. In this research, an easily programmable light-weighting methodology for a variety of internal structures is presented. A variety of advanced CAD tools are explored; however, using Rhinoceros® with the Grasshopper® graphical programming add-on, allows designers to visualize the internal structure geometry dynamically. Tensile and compression samples are quickly generated for a variety of interior configurations. Selected sample models and results, built using ABS material, are presented here. Unexpected failure occurred with the face center cubic void lattice for the compression tests. There are disjoint segments in the tool path, and unexpected voids are interspersed within the test specimen. It is found that the bead deposition path has an influence on the observed mechanical characteristics. Design constraints, and alternative internal structures are proposed, and modelled.
A Sensitivity Analysis for Effective Use of CO2 for Heat Mining in Geothermal Reservoirs
Authors: Soto-Sánchez Ana Laura , Rubio-Maya Carlos , Aguilar Corona Alicia , Chávez Oscar
Published: March 2016

Carbon dioxide (CO2) emitted from various sources, mainly fossil fuel power plants, is considered responsible of the global warming effect. Many processes and techniques are still under research for CO2 capture and sequestration. On the other hand, it is proposed that the geothermal heat be mined from geothermal reservoirs using captured CO2. In this sense, some theoretical studies show feasibility of using supercritical carbon dioxide (sCO2) as a heat mining media in such geothermal reservoirs. In this work, it is carried out a set of numerical simulations to determine the most effective distance between injection and production wells for extracting geothermal energy utilizing sCO2 (Water is used for comparison). In the study, the permeability is considered in the range of 0.5 mD to 3.5 mD, with the aim of determining also the critical point in which sCO2 works better than water (H2O) as a working fluid. The remaining properties such as volume, density and other thermal properties remain fixed. Afterwards, it is constructed a numerical model which is implemented in TOUGH2 and PETRASIM 5 software to simulate the cases established. In the model, it is considered a simplified control volume, i.e. only one well for injection and one for production, assuming a constant flow rate at the inlet and at the outlet, meaning that sequestration is not taken into account. A length of 300 meter is defined for reservoir thickness, considering also a pressure and temperature of 100 bar and 200 °C, respectively. The energy mined is estimated for a period of twenty-five years. As typically, the sensitivity analysis is performed by varying only one property and keeping the remaining properties constant, isolating in this way the effect of such variable. Results show that for small permeabilities H2O works better than sCO2, but it is possible to assure that for permeabilities greater than 1 mD, sCO2 presents more advantages as extracting heat media instead of water. Both, H2O and sCO2 show a linear behavior. A deep analysis is necessary to carry out, because results shows that sCO2 works better in an intermediate zone (greater than 200 meter length, but smaller than 800 meter length). An unusual behavior is presented when the distances between the wells are varied; water shows a linear behavior increasing monotonically, while sCO2 shows a nonlinear behavior for some distances sCO2 works better. As expected, the more the distance, the greater the amount of the energy mined due to the volume related with each one of the distances.
Parameter Identification of LuGre Friction Model: Experimental Set-up Design and Measurement
Authors: Sun Yun-Hsiang , Chen Tao , Shafai Cyrus
Published: March 2016

This work proposes a simple but general experimental approach including the rig design and measurement procedure to carry out a wide range of experiments required for identifying parameters for LuGre dynamic friction model. The design choice is based on accuracy of the estimated friction and flexibility in terms of changing contact conditions. The experimental results allow a complete LuGre model, which facilitates, but not limited to, other advanced friction modeling and high performance controller design if needed. In addition, several well-known dynamic friction features (varying break-away force, friction lag and presliding) are successfully demonstrated by our rig, which indicates the adequacy of our approach for capturing highly sophisticated and dynamic friction behavior over a wide range of operating conditions. The proposed set-up and the produced experimental data are believed to greatly facilitate the development of advanced friction compensation and modeling in friction affected mechanisms.