bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Different Sensitivity Analysis Methods in the Context of Dimensional Management
Authors: Heling Björn , Oberleiter Thomas , Schleich Benjamin , Willner Kai , Wartzack Sandro
Published: January 2018

Although mass production parts look the same, every manufactured part is unique, at least on a closer inspection. The reason for this is that every manufactured part is inevitable subjected to different scattering influencing factors and variation in the manufacturing process, such as varying temperatures or tool wear. All these factors inevitably lead to parts, which deviate from their ideal shape. Products, which are built from these deviation-afflicted parts consequently show deviations from their ideal properties. To ensure that every single product nevertheless meets its technical requirements, it is necessary to specify the permitted deviations. Furthermore it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process the imperfect parts are assembled virtually and the effects of the geometric deviations can be calculated during a variation simulation.

Since the tolerance analysis is to enable engineers to identify weak points in an early design stage it is important to know which contribution every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper two different approaches are shown and compared to represent the statistical behavior and the strongly connected sensitivity analyses. In particular a newly developed approach, which is based on fuzzy arithmetic, is compared to the established EFAST-method. The exemplary application of both methods and the comparison of the results are illustrated on a case study.
Investigations on the FSI Characteristic of a Scaled and Integral Fuel Structure Under Axial Flow
Authors: Dressel Bernd , Staude Ulrich , Hofbeck Stefan , Münch Claus-Jürgen , Kovacs Szilard
Published: January 2018

Hydraulic coupling effects are essential for the fuel assembly dynamic behavior in reactor operation and under accident conditions when the fuel structures are subjected to external excitations by core barrel motions or inlet mass flow variations. A representative testing in a flow test loop, thus, requires the consideration of several fuel assemblies in a row to assess the associated FSI effects in a relevant manner. Since the existing flow test facility at AREVA Erlangen is designed for testing of a single integral fuel structure, a scaling approach is applied to enable forthcoming flow tests in a row of scaled fuel structures. The validity of the derived scaling principles for the static and dynamic FSI characteristic is demonstrated via benchmarking flow tests between an integral bundle and a scaled down sub bundle structure of an AREVA fuel design. On an analytical level, it is shown that the implementation of a dynamic FSI coupled CFD model is capable to reproduce the dynamic behavior of the scaled fuel design in the flow tests in a quantitative and consistent fashion. This rigorous FSI modeling approach is based on the detailed flow test geometry without any adjustable parameters and, therefore, features predictive qualities for the development of simplified FSI approaches.
A Multiphase Internal State Variable Model With Rate Equations for Predicting Elastothermoviscoplasticity and Damage of Fiber Reinforced Polymer Composites
Authors: He Ge , Liu Yucheng , Bammann D. J. , Horstemeyer M. F.
Published: January 2018

This paper agglomerates an Internal State Variable (ISV) model for polymers (Bouvard et al., 2010, 2013) with damage evolution (Horstemeyer and Gokhale, 1999: Horstemeyer et al., 2000; Francis et al., 2014) into a multiphase ISV framework (Rajagopal and Tao, 1995; Bammann et al., 1996) that features a finite strain theoretical framework for Fiber Reinforced Polymer (FRP) composites under various stress states, temperatures, strain rates, and history dependencies. In addition to the inelastic ISVs for the polymer matrix and interphase, new ISVs associated with the interaction between phases are introduced. A scalar damage variable is employed to capture the damage history of such material, which is a result of three damage modes: matrix cracking, fiber breakage, and deterioration of the fiber-matrix interface, and each damage model was well calibrated to the experimental data from Rolland et al., (2016). The constitutive model developed herein arises employing standard postulates of continuum mechanics with the kinematics, thermodynamics, and kinetics being internally consistent.
Analysis of Low-Frequency Acoustic Sources in the Virginia Tech Stability Wind Tunnel
Authors: Alexander W. Nathan , Hickling Christopher
Published: January 2018

The Virginia Tech Stability Wind Tunnel is a unique low-speed facility with a Kevlar-walled test section developed for aeroacoustic measurements. A 251-channel configurable microphone array has been custom-designed for this facility to exploit the large available sensing area. Due to its large aperture, particularly for a laboratory scale instrument, the array has useful resolution down to very low frequencies, particularly in the streamwise direction. The considerable range of receiving angles and high number of sensors allows for direct measurement of source directivity. An experiment has been conducted in order to demonstrate the improved capability of the facility and investigate methods for the accurate measurement of acoustic sources at these low frequencies. Noise produced by a 50.8 mm diameter cylinder mounted in the Stability Wind Tunnel at flow speeds from 20 m/s to 60 m/s was measured. The cylinder produced shedding tones from 74 Hz to 212.5 Hz and measurable broadband noise and harmonics well beyond this. Delay and sum beamforming, deconvolution methods, and an inverse method are used to analyze the sound from the cylinder. When used in combination, these methods work well to identify the location of the source and reveal its changing directivity.
Design of Small Scale Selective Laser Sintering 3D Printer
Authors: Hough Elise M. , Gurr Alexander J. , Hans Branden , Annala Zack D. , Gar Ryan , Tsuchiya Nolan
Published: January 2018

There are several 3D printing technologies available, each offering unique benefits and drawbacks. Selective Laser Sintering (SLS) 3D printing is an up and coming market that offers high resolution and high strength components, but is generally a more expensive process reserved for advanced applications. This paper presents the design and analysis of an affordable small-scale Selective Laser Sintering (SLS) 3D printer, designed to be produced and utilized be everyday consumers. The project management structure, the design process, and preliminary analysis are key features throughout. A continuation paper publication will regard the finished SLS printer, production process, experimentation, testing, and test results.
Risk Prediction of Traumatic Brain Injury From Car Accidents
Authors: Ahmadisoleymani Seyed Saeed , Missoum Samy
Published: January 2018

The purpose of this study is to build a risk model to predict the probability of Traumatic Brain Injury (TBI). The focus is on the occurrence of one of TBI outcomes, Diffuse Axonal Injury (DAI), due to car crashes. This goal is achieved by developing a multilevel framework, which includes vehicle crash Finite Element (FE) simulations with a dummy along with FE simulations of the brain using loading conditions derived from the crash simulations. The framework is used to propagate uncertainties and obtain probabilities of DAI based on certain injury criteria such as Cumulative Strain Damage Measure (CSDM). The risk model is constructed from a support vector machine classifier, adaptive sampling, and Monte-Carlo simulations. In contrast to previous risk models, it includes the uncertainty of explicit parameters such as impact conditions (e.g., velocity, impact angle), and material properties of the brain model. This risk model can provide, for instance, the probability of DAI for a given assumed velocity.
A Design of Experiment to Study the Effects of Cutting Speed and Feed on the Generated Drilling Thrust and Torque in Aluminum Alloys
Authors: Seif Charbel Y. , Hage Ilige S. , Ismail Fathi , Hamade Ramsey F.
Published: January 2018

This work reports on an empirical study to account for the effects of the drilling parameters of cutting speed: V, m/s (max at the outer periphery), tool feed (f, mm/rev)), and drill diameter (D, mm) on the generated thrust (T, N) and torque (M, N.m). A total of 50 drilling tests were conducted on a vertical machining center based on design of experiment (DOE) test matrix using JMP-SAS/STAT® software. The test matrix employed 2 different aluminum alloys: one wrought (6061-T6) and another cast (A356-T6) with both tempered to the T6 condition. Two classical chisel drills of different diameters (10mm and 12.7mm) were used. Drilling parameter variables employed varied from very mild to very aggressive combinations including 5 values of spindle speeds (796, 1592, 3183, 6366, and 9868 rpm) and 5 values of drilling feeds (0.04, 0.08, 0.16, 0.32, 0.64 mm/rev). Drilling forces and torques were recorded using a 4-component dynamometer (Kistler model 9123) at sampling rate of 200 Hz. At full drill engagement, cutting torque and thrust status were identified for each drilling test case.

By fitting to the measured drilling forces, power law equations with parametric variables D, f, and V are developed. Initial values of the model’s power coefficients were initially identified using Matlab® using a least square optimization function with target to minimize the difference between the predicting model and the experimental data. These values were fed as initially-guessed values to the nonlinear modeling Gauss method in JMP-SAS/STAT® with 50 observations for each set of experiments. For both torque and thrust and for both aluminum alloys employed, the model’s coefficient values were identified setting the convergence criteria to 10−15 with total of 60 iterations. For both thrust and torque, it was found that the power coefficients for feed and cutting speed are statistically significant (better than p-values < 0.05) with values of about 0.7 and −0.1, respectively.
A Wireless Photonic Intraocular Pressure Sensor
Authors: Manzo Maurizio , Cavazos Omar
Published: January 2018

In this paper, we propose analytical and numerical experiments to investigate the feasibility of a wireless photonic sensor for measuring the intraocular pressure (IOP). The sensing element is a polymeric cavity embedded into a thin layer of biocompatible material integrated to a soft contact lens. The sensor concept is based on the morphology dependent resonance (MDR) phenomenon. Changes in the eye pressure perturb the micro-cavity morphology, leading to a shift in the optical modes. The IOP is measured by monitoring the shift of optical resonances. The sensor-light coupling is made through the evanescent field by using an optical prism. Therefore, the sensor can be powered and monitored wirelessly by using frustrated total internal reflection (FTIR) of a polymeric dielectric cavity. Usually, micro-optical cavities exhibit a very high quality factor Q; thus, sensors based on MDR phenomenon exhibit high resolution. Therefore, by recording tiny variations of IOP is possible to gain more knowledge about the start, comportment, and evolution of glaucoma disease.
Test Analysis of Youth and Adult Football Helmet Head Injury Risk Resulting From Repeat Impacts in High Humidity and Temperature
Authors: Saczalski Kenneth J. , West Mark N. , Saczalski Todd K. , Frausto Luis , Pozzi Mark C.
Published: January 2018

Design of an optimally safe football helmet system requires an awareness and evaluation of the factors and variables that can adversely affect the impact attenuating performance of energy absorbing (EA) pad materials needed to minimize transmission of linear and rotational forces applied to the head so that risk of head injury is reduced. For instance, player head sweating can induce high temperatures and moisture within a helmet system (i.e. a Hot-Wet condition) which can result in degradation of helmet EA capacity and cause increased measures of head injury risk levels, which are often used for comparative evaluation of helmet designs.

In this study, a “multivariable” experimental method was utilized to demonstrate an efficient means for assessment and comparison of currently representative adult and youth football helmet system designs when subjected to a range of variables that included, among other factors: temperature-moisture effects; impact energy; and, repeat impacts. Both quasi-static (QS) compression testing of commonly used EA materials and dynamic impact testing of full helmet systems were conducted and the results are presented in Tables and graphic form.

The EA pad types that were QS tested included: Thermoplastic-Polyurethane (TPU) “waffle shaped” EA pad configurations; load rate sensitive “Gel” foam padding; and, dual and single density elastomeric foam padding. Dynamic helmet repeat impact tests were conducted by using a pendulum impact test device where various helmet designs were mounted to a Hybrid-III head and neck system and impacted against a non-yielding surface at energy levels of 108J and 130J after being subjected to ambient and Hot-Wet conditions.

The QS tests showed that a short Hot-Wet soak time of only a few hours’ noticeably diminished EA levels. Also, the dynamic full helmet system testing demonstrated that the “Hot-Wet” condition tended to degrade helmet impact attenuation performance such that, depending on the size and type of EA material provided in the crush zone, head injury risk measures tended to increase. Finally, examples of the use and benefits of a “multivariable” experimental method for helmet injury risk assessment, not reported on previously, are provided.
General Interface Integral Equations in Elasticity of Random Structure Composites
Authors: Buryachenko Valeriy A.
Published: January 2018

One considers linearly elastic composite material (CM), which consist of a homogeneous matrix containing a statistically homogeneous random set of aligned homogeneous heterogeneities of non-canonical (i.e. nonellipsoidal) shape. The new general integral equations (GIE) connecting the stress and strain fields in the point being considered with the stress and strain fields in the surrounding points are obtained for the random fields of heterogeneities. The method is based on a recently developed centering procedure where the notion of a perturbator is introduced in terms of boundary interface integrals that makes it possible to reconsider basic concepts of micromechanics such as effective field hypothesis, quasi-crystalline approximation, and the hypothesis of ellipsoidal symmetry. In particular, we used a meshfree method based on fundamental solutions basis functions for a transmission problem in linear elasticity. As a particular problem allowing us to get an exact result, we consider a linear elastic CM, which consists of a homogeneous matrix containing a statistically homogeneous random set of non-canonical inclusions. The elastic properties of the matrix and the inclusions are the same, but the stress-free strains are different. Increasing of volume fraction of inclusions can lead to change of a sign of local residual stresses estimated by either the new approach or the classical one. The main properties of the method are analyzed and illustrated with several numerical simulations in 2D infinite domains containing statistically homogeneous random field of inclusions.
Experimental Investigation on the Dynamic Behaviour of a Dacron Graft Used for the Treatment of Descending Thoracic Aortic Aneurism
Authors: Amabili Marco , Balasubramanian Prabakaran , Ferrari Giovanni , Tubaldi Eleonora
Published: January 2018

The dynamic behavior of a woven Dacron graft, currently used in thoracic aortic reconstructions in the case of aneurysm or dissection, has been experimentally investigated for the first time.

Dacron grafts are widely used in cardiovascular surgery to replace segments of diseased large blood vessels; however, scarce data are available about their durability. The dynamic modeling of such prostheses may fill this gap and may provide guidelines for the study of human aortic segments as well. Dynamic phenomena such as vibrations are being included among the most likely causes of important aortic pathologies, such as dissections and consequent ruptures. The compatibility of the dynamic behavior of Dacron grafts and human arteries seems a characteristic worthy of experimental investigation as well. For this reason, a cylindrical Dacron graft has been subjected to fixed boundary conditions and to a physiological value of static axial pre-stretch. A constant internal pressure, equal to the average value of the physiologic blood pressure, was exerted by a liquid mixture of suitable viscosity and density. A three-dimensional quasi-linear viscoelastic model was fitted onto the Dacron fabric by means of dedicated traction and relaxation tests. Forced linear and large-amplitude vibrations were imposed and measured. An identification tool recently developed by this research group is being used to study the change of the equivalent modal damping ratio with vibration amplitude during nonlinear vibrations. Furthermore, an ongoing study is revealing a dependence of dissipation on frequency that is coherent to the most common model for biological materials adopted by the medical community.
Heat Transfer Effectiveness in Cylindrical Thermal Energy Storage Elements With Internal Heat Source
Authors: Suzuki George , Baghaei Lakeh Reza
Published: January 2018

The growth in renewable energy generation highlights a demand for an effective energy storage system for future power grid. Energy storage systems have a crucial role in balancing the power grid and compensating for intermittency of renewable energy sources. The state-of-the-art of grid-scale energy storage technologies (e.g., pumped-hydro and conventional compressed air energy storage) require special topological considerations; however, thermal energy storage remains as a scalable technology for storing the energy from solar thermal plans and the power grid. In this paper elemental sulfur is further investigated as a storage medium for its driving low cost and high energy storage density capabilities. Presented work numerically investigates the heat transfer behavior between elemental sulfur and an internal heat source that is placed within the thermal energy storage element. The heat transfer from the internal heat source to the thermal storage medium (elemental sulfur) is investigated computationally to understand the heat transfer behavior during charge cycle. The computations were performed with a commercial CFD package (ANSYS FLUENT) using variable properties for the storage medium. A comprehensive grid refinement study was performed to ensure the accuracy of the computational results. The results of this study show that buoyancy-driven flow induced by the internal heat source forms a rising jet toward the top of the thermal energy storage element and enhances the mixing of the boundary layer leading to enhanced heat transfer from the internal heat source.
Design of a Novel Electrode of Radiofrequency Ablation for Large Tumors: A Finite Element Study
Authors: Fang Zheng , Zhang Bing , Moser Michael , Zhang Edwin , Zhang Wenjun
Published: January 2018

Objective: The aim of this study was to design a novel radiofrequency (RF) electrode for larger and more round ablation volumes and its ability to achieve the complete ablation of liver tumors (> 3 cm in diameter) using finite element method. Methods: A new RF expandable electrode comprising three parts (i.e., insulated shaft, changing shaft, and hooks) was designed. Two modes of this new electrode (i.e., monopolar expandable electrode (MEE) and hybrid expandable electrode (HEE)) and a commercial expandable electrode (CEE) were investigated using liver tissue with and without liver tumor. A temperature-controlled radiofrequency ablation (RFA) protocol with a target temperature of 95 °C and an ablation time of 15 minutes was used in this study. Both the volume and shape of the ablation zone were studied for all RF electrodes. A large liver tumor with the diameter of 3.5 cm was used to evaluate the effectiveness on the complete ablation of the new designed electrode. Results: In the first scenario (without liver tumor), the ablation volumes of CEE, HEE, and MEE were 9.96 cm3, 41.0 cm3, and 46.14 cm3, respectively. The values of sphericity index (SI) of CEE, HEE, and MEE were 0.36, 0.94, and 0.98, respectively. The best performance was achieved by the MEE electrode. In the second scenario (with liver tumor), the ablation volumes of MEE and CEE were 67.56 cm3 and 20.62 cm3, respectively. Also, a rounder ablation volume was generated by MEE compared to CEE (SI: 0.98 vs 0.55). Conclusion: This study concludes that compared with CEE, both MEE and HEE are able to get larger and more round ablation volumes due to the larger electrode-tissue interface and more round shape of hooks; compared with HEE, MEE is better to get a larger and rounder ablation volume; MEE is able to ablate a large liver tumor (i.e., 3.5 cm in diameter) completely.
Analysis of a New Hybrid Water-Phase Change Material Heat Sink for Low Concentrated Photovoltaic Systems
Authors: Emam Mohamed , Radwan Ali , Ahmed Mahmoud
Published: January 2018

Concentrated photovoltaic (CPV) integrated with phase-change material (CPV-PCM) system is considered as a single module to reduce the CPV temperature rise and achieve higher solar conversion efficiency. For low concentration ratios (CRs), up to 20, a larger PCM thickness is needed to absorb much more heat and prolong the thermal regulation time of CPV systems. As a result, the heat absorbed in the PCM is not released efficiently to the ambient during the night time. Therefore, active heat dissipation from the CPV-PCM system is required during that time to attain full transition to solid state at the starting of each period of insolation. Thus, a hybrid CPV-PCM water system including various designs of the PCM heat sink is proposed. Such system provides a high-energy storage density during the daytime and enhances the heat extraction from PCM during the night time. To predict the thermal and electrical performance of the hybrid CPV-PCM water system, a comprehensive 2-D model for CPV layers integrated with both PCM, and water flow is developed. The model couples thermal models for CPV layers and thermo-fluid model that considers the phase-change phenomenon and water flow. Numerical simulations of the developed models are performed to determine the instantaneous liquid-solid interface evolution and the transient temperature distribution within the hybrid CPV-PCM water system. Results indicate that the hybrid CPV-PCM water system achieves a significant reduction in the CPV temperature during the daytime and improves the heat dissipation from PCM during the night time.
Thermochemical Energy Storage Using Ca(OH)2/CaO Pair for Concentrated Solar Power Plants
Authors: Ranjha Qasim A. , Vahedi Nasser , Oztekin Alparslan
Published: January 2018

Thermochemical energy storage (TES) using metal hydroxides has great potential to be used with high temperature solar power applications. TES using an indirectly heated cylindrical reaction bed for Ca(OH)2/CaO reaction system is selected for this study. Heat storage and release are carried out through endothermic dehydration of Ca(OH)2 and exothermic hydration of CaO. The bed is heated and cooled indirectly by the heat transfer fluid (HTF) flowing perpendicular to the bed axis. The reaction gas (steam) enters and leaves the bed from its top surface during hydration and dehydration respectively. Transient heat and mass transport equations coupled with chemical reaction kinetics are used for simulation of charging and discharging processes in three-dimensional geometry. The governing equations are solved using finite element method. Conversion of reactants into products and the temperature evolution within the reaction bed and HTF channel are reported for various bed sizes and Reynolds numbers within the laminar flow regime of the heat transfer fluid. It is observed that the selected reactor configuration offers clear advantages over the other configurations studied so far in terms of heat transfer and mass transport.
Investigation of Hot Water Injection Effects on Reducing Frozen Blockage in a Water Intake Unit
Authors: Wang Yifan , Tang Guangwu , Silaen Armin K. , Kirk Albert J. , Zhou Chenn Q.
Published: January 2018

The major issues affecting lake water intake structures and pipelines are frazil ice events during the winter time that reduce the intake water flow. These events can completely block the trash rack and unexpectedly shut down the intake facility. The blockages of intake trash racks occur in cold weather and under water, making them difficult to observe and measure. Computational fluid dynamics (CFD) models provide a valuable method of understanding the operating conditions and phenomena that occur inside the water intake with different blockage percentages. Hot flow is simulated to be injected into the water intake to against the frazil ice formation. Simulation results include the flow velocity, mass flow rate and the water temperature distribution. The injected flow includes hot water and steam bubbles. It is concluded that hot water injection can only heat the water flow below the trash rack, but steam bubble injection rises throughout the geometry and produces turbulences along the bubble paths.
Non-Deterministic Free Vibration Analysis of Structures With Random and Fuzzy Parameters
Authors: Feng Jinwen , Wu Di , Gao Wei , Li Guoyin
Published: January 2018

In this study, the uncertain free vibration of structures with hybrid (random and fuzzy) parameters is investigated. The non-deterministic Young’s modulus of structural elements is modeled as random variables while the uncertain mass density is represented by fuzzy parameters with associated membership functions. By implementing the α -sublevel strategy, the stochastic fuzzy eigenvalue problem is rigorously transformed into a series of stochastic interval analysis of natural frequencies. In this context, the Unified Interval Stochastic Sampling (UISS) is adopted such that the statistical characteristics of the upper and lower bounds of natural frequencies at each α -sublevel can be calculated. Subsequently, the membership functions of mean and standard deviations are respectively established for the extreme bounds of eigenvalues. Benefiting from the stochastic samples offered by the UISS method, the probability profiles of the uncertain natural frequencies at each α -sublevel can be identified by utilizing either parametric or nonparametric statistical inference methods. The accuracy and effectiveness of the proposed approach is demonstrated by analyzing a practically motivated 3D structure with comparison to the results obtained by the conventional Monte Carlo simulation method.
Experimental Investigations on Friction Factors of Gaseous Flow Through a Micro-Tube With Smooth Surface
Authors: Shigeishi Takayuki , Hong Chungpyo , Asako Yutaka
Published: January 2018

The purpose of the present study is to experimentally investigate flow characteristics on semi-local friction factors of nitrogen gas flow through a micro-tube with a smooth surface. The experiments were performed using a glass micro-tube with 266 μm in diameter and 120 mm in length. Three static pressure holes are drilled on the wall near the micro-tube outlet at intervals of 5 mm, and the local pressures were measured with the outlet discharged into the atmosphere. The local values of Mach number, temperature and friction factor were obtained from the measured local pressures. The result in the wide range of Reynolds number was also obtained, including the choked flow. Darcy friction factor and Fanning friction factor obtained under the assumptions of both a Fanno flow (adiabatic wall) and an Isothermal flow were compared with empirical correlations in the literature and numerical results.
Robust Nonlinear Finite-State Inflow Model for Lifting Rotor Coupled With Blade Flapping
Authors: Huang Jianzhe , Peters David
Published: January 2018

Real-time inflow model for lifting rotor is required for pilot-in-the-loop simulation and flight control design. The recent developed blended inflow model have advanced the state-of-the-art with closed-form solution for all three components of the flow everywhere in the field, including below the plane of the rotor disk both in-wake and out-of-wake. The nonlinearity will be introduced in such blended model to make it more flexible not only for helicopter in cruise condition, but also for helicopter in low speed flight or hover. The dynamic loading for such inflow model will be computed in real-time based on blade element theory. Then the flap motions of blades of lifting rotor will be coupled, and the induced velocity will be solved numerically in the time domain through the simpletic scheme. A Harrington rotor will be studied as an example. The induced velocity in the time domain for such a rotor will be calculated with a specific flight controls.
Analysis of Foaming Properties of Asphalt Binder Through a Laser Based Non-Contact Method
Authors: Bairgi Biswajit Kumar , Tarefder Rafiqul
Published: January 2018

Water injected foamed asphalt application in warm mix asphalt (WMA) accounts for more than 90% of all WMA technologies in past several years in the United States (US). Among different asphalt foaming variables: foaming temperatures, foaming water content (FWC), and air pressure are the major controlling factors of foamed asphalt binder characteristics. Foaming induced binder volume expansion and durability of the expanded volume are two contributing factors of foamed asphalt binder properties and foamed mixtures workability. This study evaluates the effect of FWC on foamed asphalt binder properties through a non-contact method. A laser distance meter has been utilized to record the foaming induced binder volume expansion and subsequent foamed bubbles collapse rate. Recently developed four foaming parameters such as expansion ratio (ER), half-life (HL), foaming index (FI), and stability of semis-table foamed binder bubbles (k-values) have been evaluated to characterize foamed asphalt binder. It is seen that addition of higher FWC results in a higher expansion and durability of overall foamed bubbles. Foaming parameter analysis also shows that semi-stable foamed bubbles durability is fairly constant in higher FWCs. Foamed binder rheology is also found to be correlated with FWCs.
3D Printed Quick Healing Cast: The Exoskeletal Immobilizer
Authors: Sankar Sriram , Paulose Jithu , Thomas Nirmal
Published: January 2018

A cast is used to encase a limb or part of the body to stabilize and hold anatomical structures in place to allow healing of broken bones and ligament tears by promoting immobilization. Conventional orthopedic casts have been made out of Plaster of Paris or fiberglass since ages. The traditional plaster casts have a wide range of problems that have been long since evaded due to the lack of a better alternative. Ever since the advent of additive manufacturing, many remarkable things have been made possible by the technology of 3D printing. The Exoskeletal Immobilizer is a custom 3D printed orthopedic cast that is well ventilated, light weighted, aesthetically pleasing and anatomically accurate. Even though printing the immobilizer on spot takes a little longer than the conventional cast, its countless benefits make up for the waiting time. It is extremely logical and useful for the ones suffering from cerebral palsy, who are forced to wear casts for their entire life. This project is not just another profit making business idea but is the cornerstone that is being laid to serve the people better and lead humanity into the next phase of medical advancement. By integrating parts of physiotherapy, eastern medicine, orthopedics and latest technologies, the Immobilizer promises a speedy recovery. The possibility of performing ultrasound therapy, electrical stimulation therapy, chromotherapy, cryotherapy and acupuncture therapy during the immobilization period reduces the healing time at least by about 40% [4] and eases discomfort of the patients. The features imparted to the cast have been specially handpicked and researched to provide a safe overlap of post immobilization treatment and the immobilization period to facilitate faster healing. The Exoskeletal Immobilizer can not only heal the fracture or a tear faster but can also keep the patient comfortable during the treatment.
Ultrasonic Signal Simulation for Thick-Walled Welds Based on Ray-Tracing Algorithm and Ultrasonic Field Calculation
Authors: Haipeng Zhou , Zandong Han , Yifang Chen , Dong Du
Published: January 2018

Thick-walled welds are one of the most important components of large structures, which requires effective NDT and NDE techniques. UT technique is commonly used for welds, but does not perform well in thick-walled welds because of the coarse-grained microstructures. This paper introduces an efficient method to simulate ultrasonic signals in thick-walled welds, based on an anisotropic and inhomogeneous weld model in 2D. The method consists of three major steps, including ray-tracing, field calculation and signal simulation. The ray-tracing algorithm is developed based on Ogilvy’s RayTRAIM. The ultrasonic field is calculated along the traced ultrasonic rays using the multi-Gaussian beam model. The simulated defect echoes are generated based on a flaw scattering model, according to the calculated ultrasonic fields. All the algorithms and models have been improved and optimized for higher efficiency, based on the characteristics of the 2D weld model. UT experiments were performed to verify the simulation method. An austenitic weld with four SDHs was inspected using the phased array technique. The simulated defect echoes fit with the experimental signals with acceptable deviations, indicating the validity of the simulation method. Improvement of the method is required in future study, in order to predict the ultrasonic signals more precisely.
Formulation of Problem of Free Vibration Analysis of Isotropic Homogeneous Rectangular Mindlin Plates Having Variable Thickness With General Elastic Boundary Conditions
Authors: Sourabh Sangle , Shesha Verma , Kiran Mali
Published: January 2018

This work presents a formulation for the free vibrations of isotropic homogeneous rectangular Mindlin plates with variable thickness. These plates are subjected to general boundary supports in present study. To obtain arbitrarily supported boundary conditions, new form of trigonometric series expansion functions is used as the admissible functions for transverse deflection and rotation due to bending. In order to account the constant shear stress assumption, a shear stress correction factor is taken into consideration. The Rayleigh-Ritz Method is employed in this formulation. The boundaries are assumed to have three set of springs to achieve required boundary condition. Thus the changes in boundary conditions can be easily obtained by varying the stiffness of these springs, without actually making any changes in the shape functions. In this study, FEA (Finite Element Analysis) has been carried out for the Mindlin plates, for simply supported and constrained on two opposite sides.
Reliability Assessment in Motor-Driven Compressor Units Based on D-S Evidence Theory
Authors: Zhou Dengji , Wei Tingting , Liang Maozong , Zhang Huisheng , Weng Shilie
Published: January 2018

The scientific reliability assessment is important for motor-driven compressor units, to evaluate the reliability standard, find the performance deficiency and provide references for operation and maintenance. Besides, it can reduce the test costs and accelerate the development process. Classical reliability assessment method is not suitable for the complex and reliable equipment, like motor-driven compressor units, because it is faced with the challenge of application of the multi-source information. A multi-source information based reliability assessment method is proposed in this paper. The fusion resources of this method consist of design information and operation & maintenance information. Component based and function based reliability assessment can be completed using component tests and design information. While quality evaluation based and life model based reliability assessment can be completed using operation information mainly. Finally, the unit reliability can be assessed by fusing the characteristic parameters above based on D-S evidence theory. A case study is conducted to evaluate a 20MW-class motor-driven compressor unit by this method. There are four information resources, component tests, design information, operation data and simulation data in the case. The unit reliability is assessed as 99.32% by the fusion of four reliability assessment results, acquired at different aspects. This assessment result is validated by the statistical assessment result based on long-term shutdown reports. This application points out the existing weakness in the motor-driven compressor unit and indicates directions for improving the design and operation technology. It reveals that this reliability assessment result can provide support for making a new production plan and strengthen construction of data network. Meanwhile, it has good expansibility, which may be used in more fields.
Examination of Correlation Between Arousal Level and Auditory Environmental Change Using Rock and Classic Music
Authors: Miyago Kentaro , Uehara Kenyu , Saito Takashi
Published: January 2018

Recently, traffic accidents due to drowsy driving, operation mistake in the power plant by drowsiness and decrease arousal in employment during work have been attracted as problems. To avoid such an accident, arousal level could be quantitatively evaluated in real time. We suggested that the one of the parameters of Duffing oscillator parameters is related to the conventional arousal level using the EEG frequency component. However, in this examination, effects on the EEG from visual and active behavior were considered, but those from hearing also need to be investigated. In this paper, we performed the experiment in the musical environment using rock and classic music to investigate the model parameters for effect of the auditory stimulation, and acquired EEG data in Visual cortex and Frontal lobe. The acquired EEG data was used to identify the model parameters, which were identified solving the inverse problem by Least Square method. Results of investigating correlation between conventional arousal revel and model parameter shows a significant correlation in case of the auditory environmental situation. Moreover, Visual cortex is better than Frontal lobe as a measurement point in this evaluation method.
Trimming of Flat and Tubular Components by High Speed Impact Cutting (HSIC)
Authors: Landgrebe Dirk , Barthel Tom , Schieck Frank
Published: January 2018

The trend for lightweight construction, especially in the automotive industry, leads to increased use of corresponding lightweight materials. In addition to novel construction materials such as fiber-reinforced plastics, established materials such as steel or aluminum are continuously being further developed, which is usually accompanied by a distinct increase in their strength. Beside material-related lightweight construction, new designs are applied such as the profile design.

The disadvantage of this development is that established forming processes such as deep drawing, profile bending, hydroforming but also shearing of high-strength components increasingly reach their process limits. Particularly, in the case of trimming of high-strength components such as press-hardened components, it is hard to present conventional shearing processes in serial processes due to low tool life and deficient cutting surface quality. For this reason the laser cutting technology is often used. It is characterized by high flexibility and can largely meet the requirements regarding component quality. In contrast to shearing, however, it requires very long process cycle times due to its process rate, which makes it significantly less productive.

High speed impact cutting offers an alternative. By exploiting high speed effects in the material, which leads to adiabatic heating of the shearing zone and a related significant reduction in strength, even ultra-high strength steel materials with tensile strengths of above 1500 MPa can be cut at high quality and with a short cycle time. In order to transfer this technology to serial applications and to develop process limits, extensive investigations were carried out using high-strength sheet metal materials and tube materials. The results are presented in this paper.
Research on Control Strategy of Integrated Gasification Humid Air Turbine Cycle
Authors: Wei Tingting , Zhou Dengji , Huang Di , Ma Shixi , Zhang Huisheng , Lu Zhenhua
Published: January 2018

Integrated Gasification Humid Air Turbine (IGHAT) cycle is an advanced power generation system, combining gasification technology and Humid Air Turbine (HAT) cycle. It draws great attention in the energy field considering its high specific power, high efficiency and low emission. There are only a few H AT cycle plants and IGHAT cycle is still on the theory research stage. Therefore, the study on control strategies of IGHAT cycle has great significance in the future development of this system. A design method of control strategy is proposed for the unknown gas turbine systems. The control strategy design is summarized after IGHAT control strategy and logic is designed based on the dynamic simulation results and the operation experience of gas turbine power station preliminarily. Then, control logic is configured and a virtual control system of IGHAT cycle is established on the Ovation distribution control platform. The model-in-loop control platform is eventually set up based on the interaction between the simulation model and the control system. A case study is implemented on this model-in-loop control platform to demonstrate its feasibility in the practical industry control system. The simulation of the fuel switching control mode and the power control mode is analyzed. The power in IGHAT cycle is increased by 24.12% and 32.47% respectively, compared to the ones in the simple cycle and the regenerative cycle. And the efficiency of IGHAT cycle is 1.699% higher than that of the regenerative cycle. Low component efficiency caused by off-design performance and low humidity caused by high pressure are the main limits for system performance. The results of case study show the feasibility of the control strategy design method proposed in this paper.
Experimental Investigations to Study the Effect on Coefficient of Friction and Heat Transfer Coefficient in the Lubricants With Nano Blending
Authors: Chilamkurti Lvrsv Prasad , Dharma Rao Isai , Santarao K.
Published: January 2018

Worm gears are unique in their ability to achieve large speed reductions in a compact space with gear ratios of 20:1, 60:1 and 200:1 or even higher in some cases and have transmission efficiency between 50% and 70%. One of the major drawback in worm drive design is the relative motion between the two mating elements is entirely sliding. This sliding motion continuously expels the lubricant aside leading to higher wear and increase in temperature. This phenomenon leads to high wear and higher temperatures, which are the limiting factors in the worm drives. Nano particles have gained a greater attention in the recent years because of their highly enhanced thermal and tribological properties when blended with conventional lubricants. In the present investigations the addition of Al2O3 nano particles with average particle size of 30 nm in SAE 140 gear oil resulted in reducing the coefficient of friction, wear and enhanced the heat transfer coefficient. It is observed that coefficient of friction is decreased by 8.98%, 10.11% and 16.85% at nano particle volume concentration of 0.1%, 0.2% and 0.5% respectively at room temperature. Frictional force was found reduced by 26.02% at room temperature for 0.5% volume concentration. Further it was also noted 32.25% and 18.55% reduction in frictional force at the temperatures 60°C and 90°C respectively for 0.2% volume concentration. Convective heat transfer coefficient is increased with increasing particle volume concentration and maximum enhancement of 46.35% in heat transfer coefficient observed at 0.5% volume fraction. The results depict that lubricants blended with nano particles exhibit enhanced tribological and heat transfer properties.
Micro Electromagnetic Vibration Energy Harvester Based on Combined Free/Impact Motion for Low Frequency-Large Amplitude Operation
Authors: Haroun Ahmed , Yamada Ichiro , Warisawa Shinichi
Published: January 2018

This paper presents design, simulation, and experimentation of a novel Micro-electromagnetic vibration energy harvester based on free/impact motion. Power harvesting is simply achieved from relative oscillation between a permanent magnet allowed to move freely inside a tube-carrying electrical coil with two end stoppers and directly connected to the vibration source. The proposed harvester with free/impact motion shows a non-resonant behaviour in which the output power continuously increase with the input frequency and/or amplitude. In addition, the allowable free motion permits significant power scavenging at low frequencies. Hence, the proposed harvester is well suited for the applications involved variable large amplitude–low frequency vibrations such as human-powered devices. A nonlinear mathematical model of the proposed harvester including electromagnetic and impact characteristics is derived and used further for a case study model prediction. A unique way of oscillation is observed, in which four modes of magnet/tube relative motion appear over the range of exciting amplitudes and frequencies. Two experiments are conducted on different fabricated prototypes. The first shows the effect of different magnet shapes on the harvesting performance, and the second is carried out to investigate the performance of two different size prototypes with variable large amplitude-low frequency vibrations. A harvester with cylindrical total size of D9×L12 mm can generate RMS power of 71.8μW at (2.5 Hz and 5.2 m/s2), and 113.3μW at (3.33 Hz, and 12.38 m/s2). Another of D7×L12 mm size can generate RMS power of 28.4 μW at (2.5 Hz and 5.2 m/s2), and 82.9 μW at (3.33 Hz, and 12.38 m/s2). Comparison with some previously fabricated low frequency energy harvesters is made which shows the advantageous of the new harvester in size minimization as well as the significant power raise with the input amplitude.