bluuebunny/crossref_metadata_2025 huggingface dataset:
Building a Real Time Plantar Force Measurement Sensor With LC Resonator
Authors: Chen Xinyu , Guo Yanrui , Yang Jiaoyun , Chen Hongtu , An Ning
Published: January 2018

The development of wearable equipment is posing new challenges to traditional sensors. Currently, it is important to reduce sensor size and improve sensor sensitivity so that data could be collected without interfering users’ common behavior. This article illustrates a new method for real time plantar force measurement. By paralleling planar inductive sensing coils with capacitors to form a LC resonant circuit and monitoring the change of resonant frequency or inductance, the occurrence of heel-strike and toe-off could be detected, because the change of the clearances between foot and insole triggers the simultaneous alternation of coil inductance. We conducted experiments on two different types of coils and compared them with force sensitive resistor (FSR). It is found that the Pearson correlation coefficients of these two coils’ inductance with the output voltage of FSR conversion circuit are −0.9780 and −0.7788, respectively. With smaller size and less expensive than traditional resistive sensors, this new sensing system could precisely reflect different gaits of walkers when tested in realistic situations.
Effect of Molecular Weight and Concentration on Gel-Spun UHMWPE Fibers With Polybutene as a New Spin Solvent
Authors: Fang Xudong , Jing Weixuan , Zhao Libo , Zhao Yulong , Jiang Zhuangde
Published: January 2018

Ultrahigh molecular weight polyethylene (UHMWPE) fibers have been investigated for years to improve performance with gel spinning process for wide applications in industry. Various spin solvents have been attempted including paraffin oil, decahydronaphthalene (decalin), kerosene etc. However, more work still needs to be done because of environmental issues or long extraction process of the aforementioned solvents. Recently, polybutene was found to be an effective spin solvent for UHMWPE fibers, which is environmentally friendly and widely available on the market. Besides producing high strength fibers, compared to paraffin oil, polybutene can form a gel with UHMWPE showing stronger phase separation behavior at room temperature. Because of this property, more extraction solvents can be saved. It was also demonstrated with experiments that the extraction efficiency is higher than that of the gel fiber formed with paraffin oil. Thus, polybutene has high potential to be used in large-scale production of UHMWPE fibers, which deserves further study.

In this work, polybutene with different molecular weight was used to form spin dopes with UHMWPE. The dope concentration for each type of polybutene was also varied to check the effect of molecular weight and dope concentration on fiber properties. Viscoelastic properties of the spin dopes were obtained with parallel plate rheometry while thermodynamic properties of the dopes were characterized with differential scanning calorimetry (DSC) and thermal gravitational analysis (TGA). With optimized processing conditions, high strength fibers were collected and the crystalline structure was examined with wide angel X-ray diffraction (WAXD). DSC and TGA data also provided support for the effect of molecular weight and concentration of polybutene. It can be found that stronger fibers are obtained with lower concentration spin dopes. The viscosity of the dopes and corresponding spinning conditions are significantly affected by molecular weight of polybutene. Extraction efficiency is affected by both molecular weight and dope concentration. To obtain cost-effective superstrong UHMWPE fibers, an optimized design is needed based on the molecular weight of polybutene and the spin dope concentration.
New Method in Estimation of the Turbulent Drag for the Two-Phase of Fluid Flow Through Pipelines
Authors: Radulescu Victorita
Published: January 2018

To improve the capacity of the two-phase fluid movement through the horizontal pipes, in the turbulent regime, it is necessary to determine as correctly as possible the turbulent drag coefficient and to be estimated the associated energetic balance. For a hydrodynamic flow, the gas-liquid interfacial distribution may have different possible forms, with effect in various flow patterns, due to the different flow rates of the fluid and gas. Usually, we may express the dimensionless pressure gradients as drag coefficients. During the time, some analytical available methods, described the two-phase flows in the horizontal tubes. In previous researches, the author has tested four models: the homogeneous model, the separated-flow model, the mechanistic models, and the drift-flux model. In the present paper, there were selected to accomplish the research, the results obtained from the first three mentioned models. The theoretical and experimental results proved that there are more accurate and more suitable for the actual dedicated applications. The two-phase flow is important in a large variety of applications from engineering, such as natural gas production, oil transportation, the drilling, the food processing, polymer processing industry, pharmaceutical domains, etc. In the case of flow for a single phase, the shear forces on the wall create friction, losses, followed by a pressure decreasing, known as linear hydraulic losses. In the case of the two-phase flows, an additional interaction appears between the two phases, having as consequence a supplementary difficulty in the evaluation of the pressure drop. For the mentioned models, there were considered different flow rates for oil and gas. We vary in laboratory the gas flow rate. For each model the variables were made dimensionless, to enable generalization at different types of horizontal tubes, pipelines, with different diameters. The accuracy of the developed correlations from this paper is evaluated by comparing the predictions of previous calculations and correlations with the measured and obtained results, and with the data from technique literature. The relation between the pressure gradient and mass flow is expressed also in dimensionless form, as a relation between the drag factor and the Reynolds number, considered for the two-phase flow. This one was correlated with the generalized Reynolds number, with values from 6000 to 140000. For this Reynolds range were tested in the laboratory more than 200 measurements points, for each of the three selected models. The analyzed cases allowed the estimation in a proper manner of the accuracy of the drag turbulent factor, by calculating all 10 statistical parameters, for pipes up to 80 cm.
Interactions Between Circulating Tumor Cells and Aptamer-Functionalized Microposts in a Flow
Authors: Chen Kangfu , Georgiev Teodor , Fan Z. Hugh
Published: January 2018

Circulating Tumor Cells (CTCs) have been considered as important biomarkers for cancer prognosis and treatment. However, there are only tens of CTCs in one billion of healthy blood cells. This CTC rarity challenge has been addressed by microfluidics technology that sheds light on efficient CTC detection and isolation. Using antibodies or aptamers to capture CTCs is one of the strategies for CTC isolation. A lot of work has been carried out to improve CTC capture efficiency and purity (i.e., specificity). The main consideration to optimize microfluidic device performance includes increasing surface-area-to-volume ratio and reducing shear stress, both of which are closely related to the interaction between CTCs and the microfluidic device. Here we report a detailed study on the interactions between CTCs and aptamer-functionalized microposts in a microfluidic device. We have evaluated the distribution of captured CTCs around a micropost. In addition, simulation was conducted to model CTC capture patterns around microposts. We found the simulated CTC capture pattern largely agree with the experimental results. The simulation methodology could be applicable for other affinity-based CTC isolation devices and approaches. The goal of the study is to improve the microfluidic device performance and provide a rapid and economical way to optimize the geometry design of the microfluidic devices for CTC isolation.
Determination of a Pressure Drop in the Arteriovenous Fistula With Fluid Structure Interaction Simulations and In Vitro Methods
Authors: Jodko Daniel , Palczynski Tomasz , Reorowicz Piotr , Miazga Kacper , Obidowski Damian , Jozwik Krzysztof
Published: January 2018

A pressure drop and its oscillations occurring in the arteriovenous fistula due to sudden changes in the velocity vector direction or the transitional or turbulent flow, related to its complicated geometry, can exert a significant impact on the blood vessel wall behaviour. On the other hand, the pressure drop cannot be precisely measured in vivo with non-invasive measurement methods.

The aim of this study is to assess the pressure drop with numerical and experimental methods in the patient-specific fistula model taking into account a pulsating nature of the flow and the elasticity of blood vessel walls. An additional target is to find a correlation between these two methods.

FSI and in vitro simulations of the blood flow were performed for a patient-specific model of the fistula. Basic geometrical data of the correctly functioning mature fistula were obtained with angio-computed tomography. Those data were applied to develop a spatial CAD model of the fistula, which allowed for creating a virtual model for computer simulations and an analogous in vitro model made with rapid prototyping techniques. The material used to build the in vitro model is characterised by mechanical properties similar to the arterial tissue. A non-stationary computer simulation was carried out with an ANSYS software package, keeping as many flow similarities to the experiments carried out on the test stand as possible, and where the blood mimicking fluid was a water solution of glycerine. During the experiments, the static pressure was measured downstream and upstream of the anastomosis with precise pressure transducers.

The pressure drop was determined with the numerical and experimental methods, which take into account the elasticity of blood vessels. This is a novel approach, since most of similar studies were conducted on the assumption of rigid blood vessel walls. The obtained results show that the pressure drop within the fistula is not so high as reported in the literature, which is correlated with the precision of measurement methods and the fact that a large portion of the fluid energy is accumulated by the elastic walls.
Analysis and Testing of Passenger Vehicle Bulkhead Fireworthiness
Authors: Herbst Brian , Meyer Steven , Bell Lauren , Bish Jack , Clarke Christopher
Published: January 2018

This paper presents a case study of an injury producing post-crash fire as well as testing methods to evaluate bulkhead pass through seal fire resistance and retention. In the subject crash, engine compartment fluids were released and ignited. The burning fluids entered the occupant compartment through a bulkhead pass through, resulting in rapid fire propagation and severe occupant injuries before extrication could be completed. A burn testing methodology was developed and used to evaluate the ability of the subject seal design to prevent flames and fluids from entering the occupant compartment. A retention testing methodology was also developed and used to evaluate a variety of seal designs.
The Brief Theory of Inventive Problem Solving: Practicality of Software Support
Authors: Bzymek Zbigniew M. , Lally Teresa
Published: January 2018

The ongoing challenge of research in Engineering Design is to develop a tool that can support the most difficult phase: solving problems with contradictions. The Brief Theory of Inventive Problem Solving (BTIPS) is a prospective method for performing such a task. Derived from TRIZ, TSIP, and TIPS, BTIPS differs from those methods. The Principles, Effects and Prediction modules in BTIPS are enhanced to meet the newest challenges of technology, engineering practice and pedagogy. New principles were also added to BTIPS and technological effects were enriched with new developments based on nanotechnology and biotechnology. In addition the Virtual Element procedure approach was added. The tests of functions’ separation are also the new additions. This paper includes the results of research done on the effectiveness of software that could support BTIPS in the individual studies that include applications of the available computer programs. The advantages of using BTIPS with supporting software, such as Invention Machine™, TechOptimizer™, and Goldfire™, are pointed out. Some examples are given, but others could not be discussed because of the licensing constraints. The software, if it is used during the solving process, could speed up the search for the Ideal Solution and make BTIPS even more effective in education, and even in research, and practice.
Relationship Between Conductivities and Shape Memory Performance of FDM Composite Filaments
Authors: Liu Wenbo , Wu Nan , Pochiraju Kishore
Published: January 2018

Silicon Carbide (SiC) and Carbon filled PLA Composite filaments made for use with Fused Deposition Modeling (FDM) were tested for their shape memory properties. Paper shows the relationship between the thermal and electrical conductivities of the filament and its shape recovery performance. The addition of SiC and graphite fillers accelerates the shape memory performance of PLA composites. Electrical conductivity of the filaments was characterized with I-V curves. Thermal conductivity measurements were performed, based on the ASTM D5470, on both FDM filaments and parts made with pure PLA and PLA composites. The results indicated that thermal conductivity increases with increasing SiC filler content. The conductivity increases correlate well with the reduction in the time to induce the shape recovery transition. This correlation enables control of shape transition timings in a part through the design of material composition.
Experimental and Analytical Investigation of Hanging Tubular Cantilevers With Discharging Axial and Radial Flow
Authors: Minas Sophie , Paidoussis Michael , Daneshmand Farhang
Published: January 2018

The fluid-elastic instability of hanging cantilevered pipes subject to internal and external flows is studied. Flow-induced vibrations cause these flexible tubular cantilevers to experience dynamic divergence (flutter) as well as static divergence (buckling) at high enough flow velocities. Specifically, the system studied consists of a flexible tubular hanging cantilever, which hangs concentrically within an outer rigid tube. Fluid flows internally from the clamped end of the cantilever to the free end and flows in the opposite direction in the annular region between the cantilever and the outer tube. For the system investigated, flow discharges radially from the free-end of the cantilever through the use of an end-piece. A linear model is derived in which series solutions are employed using Euler-Bernoulli beam comparison functions and is compared with experimental results. The effects of end-piece mass, confinement, pipe length, and comparisons between radial and axial flow have also been studied.
Design of a Latent Thermal Energy Storage System From Constructal Approach
Authors: Lorente Sylvie
Published: January 2018

This work presents a theoretical and numerical analysis of thermal energy storage obtained from Phase Change Materials. We start with a study of the early stages of natural convection in the liquid, followed by an analysis of the entire duration of the melting process. Both are based on scale analysis. The numerical simulations cover the entire process, and validate all the features predicted by theory. Next we apply the methodology to the design of an efficient storage system made of a tank filled with a Phase Change Material like paraffin wax. A hot fluid circulates through pipes located within the tank; it is heated by means of a solar panel. The total volume of tubes is fixed. We apply Constructal design to determine the optimal allocation of the hot tubes so that each transfer mode is used at the best moment. We demonstrate that the overall energetic performance can be improved by endowing the system with freedom to morph.
Stiffness Comparison of Triangular and Square Lattice Composites for Given Statistical Strength
Authors: Vartak Yash , Singh Gaurav
Published: January 2018

It had been claimed in an earlier article [1], using statistical theory of failure, that a triangular lattice composite structure is stiffer (i.e. has a higher overall Young’s modulus) than a square lattice composite structure for the same negligible volume fraction for a given statistical strength. In the present work, this claim has been experimentally validated. Copper/epoxy lattice composite structure is manufactured by hand-weaving copper wires of fixed size to create macroscopically isotropic structures of triangular and square shapes. The unit cell area in both cases is kept the same to ensure same statistical strength. Compressive linear response (not to fracture) of triangular and square composite structures has been recorded to measure the overall stiffness.
Dependence of Peak Stress on Crack Inclination and Friction Coefficient During Compressive Fracture
Authors: Deshpande Ameya , Singh Gaurav
Published: January 2018

In the present work, an experimental study to analyze the role of friction between the crack faces and crack inclination in compressive fracture of wood has been conducted. Different orientations of (parallel to grain) central slit cracks in wood samples were put under quasi-static uniaxial compression to measure the peak stress carried by the sample. In order to extend the analysis to different friction coefficients at the crack faces without altering other properties, the wood was kept unchanged while the crack faces were coated with paint and polish. The peak stress was largeley observed to increase with an increase in the crack inclination (wrt horizontal) and decrease in the friction coefficient between the crack faces.
An Adaptive Time Domain Approach to Characterize Dispersive Elastodynamic Media
Authors: Abedi Reza
Published: January 2018

A time domain approach is presented to compute the transmission and reflection coefficients of a unit cell. The solution of a wave scattering problem to an ultra-short incident wave enables the derivation of these scattering parameters with only one time domain solution. The adaptive operations of a spacetime discontinuous Galerkin method and several or its unique properties, such as linear solution complexity and local / asynchronous solution features, enable accurate computation of scattering parameters. An inverse parameter retrieval method, from the equivalent material impedance and wave speed to dispersive elastic constitutive parameters, is uniquely solved by using the continuity of the wavenumber.
Technoeconomic Optimization of Turbocompression Cooling Systems
Authors: Gibson Spencer C. , Young Derek , Bandhauer Todd M.
Published: January 2018

Low grade waste heat streams with temperatures near 100°C are abundant, presenting a significant opportunity to reduce primary energy consumption across the world. For example, thermally activated cooling systems can utilize waste heat to meet air conditioning loads. Recently, a turbocompression cooling system (TCCS) that utilizes low grade waste heat from power plants was investigated to improve the economic viability of dry air cooling systems. The TCCS utilizes Rankine and vapor-compression cycles that are directly coupled through a high efficiency centrifugal turbine and a compressor. In this paper, a coupled thermodynamic, heat transfer, and economic model for a TCCS is applied to utilizing low grade engine coolant waste heat to meet cargo ship cooling load requirements while minimizing the payback period for a particular operational scenario. The results of this study show that with a constant heat input of 2 MW, the liquid coupled turbocompression cooling system provided 642 kW of cooling with a payback period of 2 years and 6 months, and the total cost of the heat exchangers made up more than 84% of the total system cost. In addition, a sensitivity analysis showed that the effectiveness of the power cycle heat exchangers have a stronger influence on the payback period than the cooling cycle heat exchangers.
Effect of Thermal Treatment on Bioactivity of Experimental Dental Cement
Authors: Fialkova Svitlana , Flores Jair , Yarmolenko Sergey , Sankar Jagannathan , Ndungu Geoffrey , Wilkinson Kevin
Published: January 2018

Objective. The purpose of this study was to characterize and to evaluate the effect of thermal treatment on properties and bioactivity of experimental dental cement.

Methods. Specimens of the dental cement (pellets 13 mm in diameter × 3 mm thick) were prepared by cold pressing of micronized powder of set Alborg White Portland cement. The thermo-gravimetric analysis and differential scanning calorimetry (TGA/DSC) were used to analyze the phase composition and determine the transition temperatures for sintering process. The effect of heat rate and dwell time on density, crystal morphologies, crystalline phases and elemental composition of cement was evaluated by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and micro-Raman spectroscopy.

The bioactivity of set and heat-treated cements was evaluated by ability produce the hydroxyapatite (HA) layer on a surface of specimen immersed in a simulated body fluid (Dulbecco’s Phosphate-Buffered Saline (DPBS). The formation of hydroxyapatite was confirmed by SEM, X-ray energy dispersive spectroscopy (EDS), XRD and and micro-Raman spectroscopy. The amount of produced HA was measured by weight method after 1, 3, 7, and 14 days of immersion.

Results. The set of samples were sintered from experimental dental cement at various heating rate and dwell time. The highest density was obtained at slower heating rate and longer dwell time. The heat treatment changes the hydration phases without changing elemental composition. The heat treatment significantly improves biological performance of dental cement. The heat-treated cement produces 10 times more HA with immersion into simulated body fluid.
Knee Muscle and Ligament Forces During Drop Landing Exercise
Authors: Caruntu Dumitru I. , Moreno Ricardo , Freeman Robert
Published: January 2018

This work investigates the human leg muscle and ligaments forces during a drop-landing exercise. An inverse dynamics 2-D model of human leg is used on this ballistic task in order to predict these forces. The model consists of three bony structures, namely femur, tibia, and patella. The joints of the model are the knee joint and the hip joint. The ligamentous structure of the knee includes the two cruciate ligaments, Anterior Cruciate Ligament (ACL) and the Posterior Cruciate Ligament (PCL), and the two collateral ligaments, Lateral Collateral Ligament (LCL) and Medial Collateral Ligament (MCL). The system of muscles of the system includes muscle such as quadriceps, hamstrings, gastrocnemius are included in the model. Experimental data used show a maximum of 100 degrees of flexion angle and ground reaction forces up to 4 times the body weight. The inverse dynamics 2-D model consists of an objective function to minimize the muscle forces, and a set of constraints consisting of equality constraints which are the dynamics equations of the bony structures, and inequality constraints in which all muscle forces must be positive. All muscle forces show a pattern in which they reach large magnitudes at the beginning of landing, decreasing as the subject end the exercise with a standing position.
Speech Assistance for Persons With Speech Impediments Using Artificial Neural Networks
Authors: Mounir Ramy , Alqasemi Redwan , Dubey Rajiv
Published: January 2018

This work focuses on the research related to enabling individuals with speech impairment to use speech-to-text software to recognize and dictate their speech. Automatic Speech Recognition (ASR) tends to be a challenging problem for researchers because of the wide range of speech variability. Some of the variabilities include different accents, pronunciations, speeds, volumes, etc. It is very difficult to train an end-to-end speech recognition model on data with speech impediment due to the lack of large enough datasets, and the difficulty of generalizing a speech disorder pattern on all users with speech impediments. This work highlights the different techniques used in deep learning to achieve ASR and how it can be modified to recognize and dictate speech from individuals with speech impediments.
Non-Destructive Inspection of Surface Defects in Cylindrical Structures
Authors: Du Jikai
Published: January 2018

Cylindrical structures have been applied in various pressure vessels and weapon systems, which may be subjected to harsh environmental conditions such as large mechanical stresses and thermal stresses. As a result, non-destructive evaluation of such structures is critical in quality control. Among the various defects that may be generated during fabrication, transportation, operation/firing, and so on, surface crack is a critical one and needs to be quantitatively and accurately evaluated. In this study, both ultrasound phased array technique and eddy current technique are applied for the inspection of 120 mm steel test cylinder. In the cylinder, a total of nine sets of surface defects of various size, depth and orientation are fabricated and quantitatively evaluated.

In ultrasound phased array evaluation, simulations and experiments on standard aluminum block were carried out first to calibrate the system parameter setup. During this calibration, ultrasound propagation and its interaction with defects were simulated and studied. The dependence of ultrasound field on the ultrasound parameters and on the characteristics of defects was analyzed and optimized. Then simulations and experiments on steel test cylinder were carried out for the detection of the smallest detectable defects. Results showed that the optimization of the number of active elements can improve the distortion of defect images; the steering angles and the beam focusing laws may change the ultrasound beam intensity and uniformity, which has a significant influence on the sensitivity and resolution of the phased array technique; the geometry and material properties of cylindrical structures could distort the ultrasound beam, and as a result, calibration is necessary and important during practical inspections. Frequency is a key factor for phased array technique to improve its sensitivity.

In eddy current evaluation, a prototype for wireless eddy current system was designed, and an eddy current probe interface and a main unit interface were developed. The main advantages of such wireless probe are safety, economic benefits and maneuverability when compared to conventional wired probe. During testing, the signal at the probe interface was activated, measured, digitized and transmitted wirelessly to the main unit interface. Experimental results showed that the eddy current signals can be wirelessly communicated with main unit, and the results are comparable with the wired eddy current tester. Testing results also showed that the wireless signal is about 8 dB lower compared to wired signals and phase difference exists between the wired and wireless signals.
3-D Printed Orthotic Hand With Wrist Mechanism Using Twisted and Coiled Polymeric Muscles
Authors: Sharma Ashvath , Saharan Lokesh , Tadesse Yonas
Published: January 2018

Most stroke victims undergo muscular disorders leading to weakening of muscles and inability to perform normal hand activities. An exoskeleton device is therefore needed to aid in performing basic hand movements to improve the quality of life of the victims. Most of the available devices in literature are controlled using electrical motors with a rigid structure and complex design. This paper discusses the design and performance of an inexpensive and lightweight 3D printed orthotic device featuring a wrist mechanism. The design is simple and utilizes twisted and coiled polymeric (TCP) muscles which are easy to fabricate using a silver coated nylon 6, 6 threads. The device facilitates the movement of all the three joints of the human finger namely, distal interphalangeal joint (DIP), proximal interphalangeal joint (PIP) and the metacarpophalangeal joint (MCP). Experiments were performed using a custom-made hand which was 3D printed and casted using silicone rubber with a shore hardness 10 (Ecoflex® 010) to resemble an actual human hand. The results showed the range of motion achieved with the device, grasping and pinching of various objects with assistive efforts using TCP muscles and demonstrated the capability of the device to achieve flexion and extension of the fingers mimicking the human finger movements.
A Calibration Approach for Installation Error of Multi-Axis Laser Interferometer
Authors: Du Shengwu , Hu Jinchun , Zhu Yu , Tian Chang , Zhang Ming
Published: January 2018

Multi-axis laser interferometer is generally employed in measuring multi-degree-of-freedom (M-DOF) displacement for many ultra-precision X-Y stages. In multi-axis measurement system, the installation deviation of interferometer laser beam is an important error source. In this paper, a novel calibration approach without other higher precision sensors has been presented, to calibrate the installation deviation in a 3-DOF displacement measurement system, with potential capability of calibrating 6-DOF measurement system. In the proposed method, one redundant measuring axis that is set as installation reference axis is added to the original 3-axis measurement system. Correspondingly, considering the installation deviations of 3-axis interferometer, a new displacement computational model with four equations is built. In this model, all installation deviations are constants and the displacement values are variable. Utilizing the redundant measurement information of three position points, the installation deviations are separated. The simulation results validate its feasibility. This approach can strictly ensure the parallelism and perpendicularity between measuring axes, and is easily applied to engineering.
Effect of Electrical Current on Cold Work in Aluminum 2024
Authors: Shaffer Derek , Sehman Sean , Ragai Ihab , Roth John T. , Wang Bin
Published: January 2018

Many manufacturers are looking towards electrical treatments as methods for reducing residual stresses in formed metals. Although many people have investigated the effects electricity has on residual stresses and plasticity, there has not been research investigating the effects it has as a post-treatment on strain hardening. Therefore, the goal of this research is to show the permanent changes in tensile properties that electrical treatments have on strain hardened metals, specifically Aluminum 2024. For this initial investigation, only one pulse duration and current density was used to categorize any changes in the metals due to applying electric current. This testing shows the difference between post-deformation heat treatments and post-deformation electrical treatments. Tensile properties of Aluminum 2024 were used to gauge the changes caused by the treatments. The heat treatment had the expected effect of lower the strength of the material and regrowing the grains while the electrical treatment did not seem to drastically change the structure of the grains, but still lowered the strength of the material. Microstructure investigations also showed that the material does in fact show slight changes in material properties, but no drastic changes in microstructure. These images also show that the regrowth from the heat treatment is clearly the reason for the decrease in strength.
Study on Chip Formation and Simulation of Cutting In-Situ TiB2 Particle Reinforced 7050Al Metal Matrix Composites
Authors: Xiong Yifeng , Wang Wenhu , Jiang Ruisong , Lin Kunyang , Shao Mingwei
Published: January 2018

The in-situ TiB2/7050Al composites is a new kind of particle reinforced metal matrix composites (PRMMCs) with superior properties such as low density, improved strength and increased wear resistance. At present, the study of PRMMCs is focused on the ex-situ SiCp/Al composites, which has been researched from material preparation process to machinability. To the new kind in-situ TiB2/7050Al MMCs, few papers have been published on the cutting performance and finite element method (FEM) simulation. This work involves study on the chip formation and FEM simulation in cutting in-situ TiB2/7050Al MMCs. The orthogonal cutting experiments were carried out in our study. The chip geometric shapes, cutting forces and shear angle were investigated. Meanwhile, the cutting simulation model was established by applying Abaqus-Explicit method to have a deep insight of the chip formation process and mechanisms. The results show that the saw-tooth chips were common found under either low or high cutting speed and small or large feed rate. The mechanisms of chip formation included plastic deformation, adiabatic shear, shear slip and crack extension.
Total Temperature Measurement of Gas at Microtube Outlet
Authors: Sakashita Takeya , Hong Chungpyo , Asako Yutaka
Published: January 2018

This paper describes experimental results on the total temperature measurement of gas at the microtube exit. In order to measure the total temperature at the microtube outlet, two total temperature measuring devices with different structures were fabricated. One is six plastic baffle plates embedded inside with a thermally insulated exterior foamed polystyrene tube. The other is two glass fiber thimbles embedded inside it. The gas velocity was reduced by the plastic plates and the glass fiber thimbles, and the kinetic energy was converted into thermal energy. The fundamental premise of the total temperature measurement is the Joule Thomson effect present in real gases, which for a positive of the Joule Thomson coefficient involves the decrease in temperature when the gas experiences isenthalpic expansion. A PEEK microtube whose nominal inner diameter and outer diameter were 500 μmm and 1.6 mm, was used for assessing exact measurement of total temperature in the temperature measuring tube, since the thermal conductivity of the PEEK tube is very low. The measured total temperatures were compared with those obtained theoretically with the Joule Thomson coefficient and given thermodynamics properties.
Comparative Energy Cost Analysis of Hybrid System and Diesel Generator in Powering Selected Base Transceiver Stations in Nigeria
Authors: Oviroh Peter Ozaveshe , Jen Tien-Chien , Idusuyi Nosa , Gbadeyan Olushola
Published: January 2018

The rapid increase in global communication infrastructure in developing countries has drawn significant attention to the telecom sector. However, the dismal performance of the power sector in some countries like Nigeria poses a great challenge to the telecom industry which requires a reliable, efficient and environmentally friendly energy supply. Unstable electric grids, an erratic power supply, non-availability of trained and skilled personnel, and a prohibitive cost of site maintenance cumulatively have increased the need to harness abundant renewable energy sources, such as solar and wind. A comparative study of the viability of solar-diesel hybrid against diesel-only generator systems in powering a base station using the cost of kilowatt hour (kWh) self-generated electricity and levelised cost of energy (LCOE) was undertaken using data from some sites located in the Southwest (SW) and the Northeast (NE) regions of Nigeria. Homer Pro Software was used in data analysis.

The results obtained showed that with a hybrid energy system (solar and diesel generator), there were 79% savings in fuel consumption, 83.2% savings in operation and maintenance cost for the hybrid energy system in the SW. The savings on fueling as a result of the use of hybrid systems was 86%, and the carbon footprint reduction was 76%. Furthermore, the cost of operation was reduced by 51% for Northeast. The LCOE for the solar hybrid system was determined to be $1.44 for NE1A and NE1B while that of NE2A was $1.46 and NE2B $1.47.
Microhardness and Microstructural Studies on Underwater Friction Stir Welding of 5052 Aluminum Alloy
Authors: Pedapati Srinivasa Rao , Paramaguru Dhanis , Awang Mokhtar
Published: January 2018

As compared to normal Friction Stir Welding (FSW) joints, the Underwater Friction Stir Welding (UFSW) has been reported to be obtainable in consideration of enhancement in mechanical properties. A 5052-Aluminum Alloy welded joints using UFSW method with plate thickness of 6 mm were investigated, in turn to interpret the fundamental justification for enhancement in mechanical properties of material through UFSW. Differences in microstructural features and mechanical properties of the joints were examined and discussed in detail. The results indicate that underwater FSW has reported lower hardness value in the HAZ and higher hardness value in the intermediate of stir zone (SZ). The average hardness value of underwater FSW increases about 53% greater than its base material (BM), while 21% greater than the normal FSW. The maximum micro-hardness value was three times greater than its base material (BM), and the mechanical properties of underwater FSW joint is increased compared to the normal FSW joint. Besides, the evaluated void-area fraction division in the SZ of underwater FSW joint was reduced and about one-third of the base material (BM). The approximately estimated average size of the voids in SZ of underwater FSW also was reduced to as low as 0.00073 mm2, when compared to normal FSW and BM with approximately estimated average voids size of 0.0024 mm2 and 0.0039 mm2, simultaneously.
Improving Manual Control of Two-Link Pendulum on Gantry Crane With Anti-Delay Closed-Loop Input Shaping
Authors: Chatlatanagulchai Withit , Pongpanich Nitirong , Yaemprasuan Pisai
Published: January 2018

This paper presents a novel and improved technique in manual control of flexible systems. Flexible systems, when subject to a rapid movement commanded by a human operator, exhibit severe oscillation, causing low positioning accuracy, high fatigue to the human operator, and unsafe accidents. Input shaping filter was proposed to reduce this oscillation by using the destructive interference principle where impulse responses cancel one another resulting in zero residual vibration. Recently, the input shaping filter was placed inside the feedback loop, so-called closed-loop signal shaping, to assist with the manual control of the flexible systems. The vibration was successfully suppressed. However, the input shaping filter also introduced time delays in the feedback loop, which limit the performance of the human operator. This paper offers a breakthrough idea by introducing an anti-delay algorithm called Smith predictor inside the feedback loop. When the plant model is perfect, it can be shown that the Smith predictor can entirely remove the effect of time delay from the feedback loop; therefore, improving the performance of the human operator. Experiments on manual control of a two-link pendulum on a gantry crane show the effectiveness of the proposed algorithm. The human operator was able to move the two-link pendulum with minimum residual vibration. Comparing to the currently world-best technique, the proposed technique could achieve faster maneuvering time, higher accuracy, and with less subjective difficulty.
Influence of the Young’s Modulus on the Velocity of Ultrasonic Waves to Measure Mechanical Stresses
Authors: Pereira Paulo , Antunes dos Santos Auteliano
Published: January 2018

The state of stress in mechanical components can be evaluated non-destructively using ultrasonic waves. The relation between stress and the velocity of elastic waves in a solid is given by the acoustoelastic theory. Among different types of ultrasonic waves, the longitudinal critically refracted (Lcr) wave is more sensible to stress variations. However, not only stress, but also other factors can influence the velocity of ultrasonic waves, as for example, the microstructure of the material under test. Since the Young’s modulus is affected by variations of the microstructure, a relation between wave velocity and the modulus would allow corrections of the values of wave velocity obtained during stress measurements. The aim of this work is to find a relation between the Young’s modulus and the velocity of Lcr waves for specimens of API 5LX70 steel. The material chosen in this work is used in the manufacture of pressure vessels and oil pipelines. Assessing the state of stress of such components in field can guarantee operational safety and economic gains by avoiding premature replacements. The time-of-flight (TOF) of the Lcr wave was measured in four samples of API 5LX70 steel and the results were related to the Young’s modulus measured in a tensile test and through ultrasonic tests. Since the distance traveled by the wave in the specimens was kept constant, the TOF was used instead of the wave velocity. The results showed a linear relation between the TOF measured and the Young’s modulus obtained by ultrasound and tensile test in the samples.
A Study of a Non-API Flange
Authors: Alam Shah , Dakeev Ulan
Published: January 2018

API rated flanges [1] are used in oil and gas industries frequently. The current practice is to select a flange and its seal/gasket from a tabulated range of load and area of application. Some applications may require a unique flange or seal for a pressure and temperature that is not listed on the table. To design such non-API flange (geometry such as thickness, number of bolts, bolts pattern, etc. are different from API flange) that meets system requirements is a challenge. Currently there is no standard available as per authors knowledge to design non-API flange. Therefore, in this study, a finite element analysis with new acceptance criterion for the 5”-15-ksi non-API flange connection for different pressure and temperature has been performed. Elastic-plastic finite element analysis method is used to check the leak tightness [2]. A fatigue calculation based on elastic-plastic analysis with twice yield method as per ASME Section VIII, Division 2 [3], sec. 5.5.4, has also been performed.

A new acceptance criterion based on industry practices are used for leak tightness. The contact pressure and contact pressure band width are used to check the leak tightness. The results showed that for all load cases seals have enough contact pressure and contact pressure band width to prevent leakage and they meet the acceptance criteria. The calculated fatigue life was found more than the required life for an application.
Correlating Dynamic Bifurcations With Impedance Measures for Multistable Structures
Authors: Goodpaster Benjamin A. , Harne Ryan L.
Published: January 2018

Slender, lightweight structures are demanded to meet efficiency targets or to enhance vehicle system performance characteristics. Yet, when subjected to static stress for load-bearing purposes, the flexible structural members may buckle. Furthermore, additional dynamic excitations may activate adverse snap-through responses in such post-buckled components, which accelerates fatigue and failure. The severe nonlinearity associated with these phenomena challenges traditional forms of analysis and necessitates studious experimental methods for conclusive system characterization and model validation. This research builds upon state-of-the-art analytical and experimental strategies to examine the complex forced, dynamic behaviors of built-up structures that contain one or more post-buckled members. An analytical modeling and solution formulation is reviewed that is uniquely amenable to the study of multistable structures and permits experimentally-observable measures of impedance to be identified. Through theoretical and experimental studies, the efficacy of the impedance measures is evaluated towards their usefulness in identifying the onset of dynamic bifurcations in the multistable structural dynamics. For moderate amplitudes of input energy, the analysis is found to provide qualitatively accurate prediction of the drive point impedance changes observed prior to dynamic bifurcations from low to high amplitude of displacement.
A Computer Vision Approach for Balancing of Rotating Machines
Authors: Nejadpak Ashkan , Yang Cai Xia
Published: January 2018

Unbalance is one of the most common mechanical faults in rotating machines. Different balancing methods to stabilize the unbalanced rotor are investigated in this paper. One approach of using solely the accelerometers data and intricate vibration theories is discussed. Although the method can eliminate the need of balancing equipment, and the amplitude and phase of the machine’s vibrations can be identified, it needs numerous measurements, and in some cases is impossible to be implemented. Therefore, a novel approach with reduced number of required measurements is proposed. Our method only requires two measurements, one from the original unbalanced condition, and the other from modified situation after adding an arbitrary trial mass to a marked location on the rotor. The rotating rotor is being video recorded during this process. The goal is to identify the position of the marked area whenever the amplitude of the sinusoidal vibration response reaches the maximum. To demonstrate the effectiveness of our method, an experiment is setup. Vibration of healthy and unbalanced flywheel attached on a three-phase induction motor is analyzed in both time and frequency domains. The rotation of the motor is video recorded under original unbalanced and modified situations. The correction mass and its adding location are calculated using proposed method. The vibration analysis of balancing result demonstrated that the system got dynamically balanced by adding right value and location of a mass. The method proposed and developed in this paper is more cost effective with the same accuracy as the other contested balancing techniques.
Impact of Grain Boundaries on the Heat Conductivity of Mono-Layer Hexagonal Boron Nitride
Authors: Elapolu Mohan S. R. , Tabarraei Alireza
Published: January 2018

Reverse nonequilibrium molecular dynamics modeling is used to study the influence of grain boundaries on thermal properties of mono–layer hexagonal boron nitride (h–BN) nanoribbons. We consider symmetric grain boundaries consisting of series of pentagon–heptagon ring defects. Our results show a jump in the temperature profile at the location of grain boundary. The jump is consistently increasing with increase in the mis-orientation angle of nanoribbons with grain boundaries. This is attributed to an increase in the pentagon–heptagon defect density along the grain boundary. The temperature profile is used to calculate the Kapitza (interface) conductance of grain boundaries as a function of the misorientation angle of grain boundaries. Our results show that Kapitza conductance of the grain boundaries decreases with increase in the misorientation angle. Zigzag nanoribbons show slightly higher Kapitza conductance than armchair nanoribbons.