bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Flexoelectric and Piezoelectric Actuating of Beams
Authors: Fan Mu 
Published: February 2021

Abstract
The flexoelectric and piezoelectric effect on the actuating of a cantilever beam are compared in this study to explore how the size-dependent effect could affect the application of the flexoelectric effect. An AFM (atomic force microscopy) probe is used to generate the electric field in the flexoelectric patch, significant electric field gradient is induced. The electric field, distribution of control moment, induced modal force and the vibration control efficiency in terms of transverse displacements are analyzed in case studies. Analytical results show that the control moment of flexoelectric effect highly concentrates at the location of the AFM probe due to the inhomogeneous electric field, which shrink the effect area of flexoelectric patch size. The distribution of the flexoelectric control moment is an impulse function and the distribution of the piezoelectric control moment is a step function, which results to the flexoelectric modal force strongly affected by the electric field gradient while the piezoelectric modal force highly depends on the patch size. For the flexoelectric actuating, decreasing the AFM probe radius can increase the electric field gradient and induce larger modal force. The thickness effect of flexoelectric patch depends on the electric field gradient and the control moment arm, and in the current study, increasing the patch size, the induced flexoelectric modal force increases slightly. Case studies on vibration control show that both the flexoelectric actuating and piezoelectric actuating could generate larger transverse tip displacement with increasing the patch size. This study proves that the flexoelectric actuating can provide effectively actuating and control effect to engineering structures when the size decreases.
A Pseudo S-Plane Mapping of Z-Plane Root Locus
Authors: Noury Keyvan , Yang Bingen 
Published: February 2021

Abstract
In this paper, inspired by the geometric inversion transformation, a novel transformation of the z-plane root locus to a pseudo s-plane is proposed. In the z-plane, the stability of a discrete closed-loop system (a sampled-data control system) requires that all the system poles lie within the unit circle. In root locus analysis, the unit circle region seems congested, compared to the stability region of a continuous system, which is the left half of the s-plane. In the case of fast sampling, the poles of a discrete system can really be in a small neighborhood, thus making the control implementation difficult. The geometric transformation developed in this work helps widen or enlarge the space for the system poles and preserves most of the features of z-plane root loci, including marginal stability and root loci branching off at vertical angles. The usefulness of the new transformation in design of discrete control systems is demonstrated in a numerical example.
Preparation and Characterisation of Graphene Nanofluid: To Be Used As Coolant
Authors: Velukkudi Santhanam Senthil Kumar , Austen Thomas Dolly , Michael Duke Mystica Augustine , Doraiswamy Viswanathan 
Published: February 2021

Abstract
In the recent years, nanofluids embarked as a new class of fluids with improved thermophysical properties such as thermal conductivity, thermal diffusivity, viscosity, and convective heat transfer coefficients thus promoting better heat transfer. Nanofluids consists of two-phase system where the nano sized solid phase (nanoparticles) is dispersed into a base fluid. Graphene is a material which has two-dimensional planar geometry with thermal conductivity of the order of 5000 W/mK. Nanoparticles in the form of thin flakes as small as 50 nm, 100 nm has been used in this study. Two step technique is the used method for preparing nanofluids. Inclusion of additives in small quantity, enhance the durability of the nano particles inside the conventional base fluids. The stability of the solid nano particles inside the conventional base fluid is increased by using surfactants. The heat transfer capacity and stability of the fluids are considered as the basic properties for investigation. The nanofluids characterization studies were drawn from the SEM, XRD and thermal conductivity results. Hot wire method was used to determine the thermal conductivity of the nanofluids. The preparation and properties of graphene based nanofluids which can be used as coolant are studied in this work.
On Calculation of Leakage Flow in Screw Compressor Elements
Authors: Stosic Nikola 
Published: February 2021

Abstract
The computation of the gas velocity in leaking paths which may contain labyrinth elements of screw compressors is developed from the continuity, energy and momentum equations. It accounts for the effects of the local loss of flow kinetic energy and line fluid-wall friction by assuming that the fluid is an ideal gas at constant temperature to eliminate gas density.
This is straightforward situation if the clearance leakage flow is considered to happen in a single leakage gap element, however, if a series of leakage elements are applied, as for example, it happens in a labyrinth seal components, there will be a pressure drop in each groove which in sum will give the overall pressure drop.
A sensitivity analysis of the compressor design parameters that influence such a sequence of the labyrinth seal performance upon that the leakage flow strongly depends upon the gap clearance and only weakly depends on the clearance length and the number of labyrinth grooves. The influence of the number of grooves becomes even weaker if the entire kinetic energy of the leakage flow is not fully dissipated in the labyrinth grooves.
On the Manufacturing Defects of Thermoplastic Carbon/Epoxy Composites Manufactured by Automated Tape Placement
Authors: Sebaey Tamer A. , O’Dowd Noel 
Published: February 2021

Abstract
Thermoplastic composites are highly recommended for structural application, not only for their superior characteristics derived from the fiber and matrix materials but also for their recycling possibilities, which is a major issue in the today’s engineering practice. The manufacturing techniques for thermoplastics are different from those for the well-established thermoset composites. This paper addresses the quality of the thermoplastic composites by assessing the distribution of the fiber, the void contents and the waviness of the fibers, compared to the thermoset composites. IM7/PEEK and AS4/PA12 are the two thermoplastic composite systems used for this study, whereas, IM7/8552 is the thermoset composite used as reference. The specimens were examined using optical microscopy and computed tomography (CT) and the results were statistically treated using circular statistics. Compared to the IM7/8552 composite, the analysis reveals that the IM7/PEEK and AS4/PA12 composites, manufactured by ATP result in a higher volume of voids. On the other hand, ATP processing improves the alignment of the fibers, as the solidification process occurs while the fibers are in tension. The microscopy studies also show that the ATP manufactured composites have an area in between the different layers of tape with a low number of fibers, compared to the other areas.
Autologous Ear Reconstruction: A Semi-Automatic Procedure for Patient-Specific Surgical Guides
Authors: Mussi Elisa , Furferi Rocco , Servi Michaela , Volpe Yary , Facchini Flavio 
Published: February 2021

Abstract
Autologous ear reconstruction, i.e. the reconstruction of the outer ear from autologous cartilage tissue, is a very important surgery considering the psychosocial repercussions of an individual affected by microtia (i.e. the total or partial absence of the outer ear). The execution of this surgery can be very complex due to the unique characteristics of this anatomical region. In order to help the surgeon in the process of cutting and suturing, innovative surgical guides were designed that can transmit information about the shape and size of the anatomy to be reconstructed. This work lays the foundation for the creation of a semi-automatic and easy-to-use tool for the modeling of surgical guides. The goal is to make the hospital staff autonomous in the creation of instruments that can be used in pre-surgical simulation and during surgery.
An Evaluation of Mode Tracking Methods for Practical Rotor Dynamic Analysis
Authors: Rajagopal Anurag , Mandal Dilip K. 
Published: February 2021

Abstract
An important precursor to the dynamic analysis of rotating machinery, in either frequency or time domain, is the extraction of its mode shapes and corresponding frequencies. This is often presented as a Campbell diagram, which plots the frequency of each mode as a function of the rotor speed. A typical Campbell diagram has several backward whirl, linear and forward whirl modes leading to numerous intersections. Therefore augmenting the eigenvalue solution with a mode tracking algorithm to output the Campbell diagram is of essential interest to a practicing engineer. This paper presents an evaluation of several mode tracking approaches for rotor dynamic simulations, starting from their theoretical foundations to practical applications using several test cases. These tracking algorithms are implemented in the structural solver, OptiStruct, part of Altair Engineering’s CAE framework. Finally, the conclusions drawn from this exercise offer engineers studying rotating machinery several key insights.
Modeling of Compliant Mechanisms in MATLAB Simscape
Authors: Pena Paul , Garcia Martin , Tekes Ayse 
Published: February 2021

Abstract
This paper presents the informative process of modeling of compliant mechanisms using MATLAB Simscape. Simscape is the modeling environment analyzing both rigid and flexible systems using either the blocks provided in the library or the CAD models imported from modeling software. We present the modeling of four compliant mechanisms: dwell, five bar, translational and hopping mechanisms. Once the cad model of a system is imported into Simscape, the flexible links or flexure segment on each example system is replaced by its equivalent lumped parameter block. Compliant dwell mechanism is comprised of a rail, two pinned-pinned flexible links, slider, rigid crank and a DC motor. The second mechanism is a fully compliant five bar mechanism incorporating large deflecting flexures and actuated by two servo motors. The objective is to control the trajectory of the tip position. Third example models a bio-inspired translational compliant mechanism driven by servo motors and comprised of three sliders connected by single piece designed 2 rigid arm-flexure hinge linkages mimicking the motion of a caterpillar. The last example is the modeling of a compliant hopping robot consisting of two pairs of gears; one pair is attached to the motor and the other pair allows the bottom links to rotate at same angular velocity in opposite directions.
Effects of Rapid Microwave-Curing on Mechanical and Piezoresistive Sensing Properties of Elastomeric Nanocomposites
Authors: Herren Blake , Saha Mrinal C. , Altan M. Cengiz , Liu Yingtao 
Published: February 2021

Abstract
Carbon nanotubes (CNTs) have the unique ability to absorb microwave radiation and efficiently transfer the energy into substantial heat. When adequately dispersed in a thermoset polymer, such as polydimethylsiloxane (PDMS), the nanocomposite can be fully cured in seconds in a microwave oven rather than in hours in a convection oven. In this paper, cylindrical PDMS nanocomposites containing well-dispersed CNTs are fabricated by either microwave-curing or conventional thermal-curing. The mechanical, electrical, and piezoresistive properties of the fabricated samples are compared to understand the effects of different curing methods. Microwave-cured nanocomposites exhibit a significantly reduced compressive modulus for different CNT loadings. In addition, the electrical conductivity of microwave-cured nanocomposites is significantly enhanced over the thermally-cured counterparts. Experimental results demonstrate that the one-step microwave-curing procedure can improve the electrical conductivity of 1 wt% nanocomposites by almost 150 % over thermal-curing. However, their piezoresistive sensitivity remains remarkably similar, showing the potential for microwave-curing to replace thermal-curing for the manufacturing of highly flexible CNT-based nanocomposites.
Quantifying the Accuracy of a Motion Detecting Neural Prosthesis
Authors: Tanaka Martin L. , Subbukutti Premkumar , Hudson David , Hudson Kimberly , Valenzuela Pablo , Yanik Paul 
Published: February 2021

Abstract
The neural prosthesis under development is designed to improve gait in people with muscle weakness. The strategy is to augment impaired or damaged neural connections between the brain and the muscles that control walking. This third-generation neural prosthesis contains triaxial inertial measurement units (IMUs - accelerometers, gyroscopes, and processing chip) to measure body segment position and force sensitive resistors placed under the feet to detect ground contact. A study was conducted to compare the accuracy of the neural prosthesis using a traditional camera motion capture system as a reference. The IMUs were found to accurately represent the amplitude of the gait cycle components and generally track the motion. However, there are some differences in phase, with the IMUs lagging the actual motion. Phase lagged by about 10 degrees in the ankle and by about 5 degrees in the knee. Error of the neural prosthesis varied over the gait cycle. The average error for the ankle, knee and hip were 6°, 8°, and 9°, respectively. Testing showed that the neural prosthesis was able to capture the general shape of the joint angle curves when compared to a commercial camera motion capture system. In the future, measures will be taken to reduce lag in the gyroscope and reduce jitter in the accelerometer so that data from both sensors can be combination to obtain more accurate readings.
Advanced Data Center Cold Aisle Airflow Organization Optimization Using an Adjustable Fan Unit
Authors: Song Zhihang , Zhang Qian 
Published: February 2021

Abstract
The real-time smart data center cooling has become a key to maintenance and operation of energy-efficient data centers, primarily including the server inlet airflow/thermal domains. Here, the cold-aisle airflow phenomena in a widely-used cold/hot aisle data center configuration was under parametric investigation, This concern is mainly because of the airflow separation and recirculation from the stream emerging from the server outlet and returning to the computer room air-conditioning unit. In order to achieve a better understanding and to correspondingly eliminate the negative effects of the hot air over-tack recirculation towards a satisfied effectiveness, an addition of a rack-level adjustable fan unit (AFU), which is placed inside the cold aisle, was considered at an early stage and the model prototype was numerically analyzed with respects to differently predefined parameters. The cooling performance consequence, consisting of the server-neighbored inflow rates and maximum server inlet temperatures explored by computational fluid dynamics (CFD) observation panel and sensors, demonstrates that the over-rack air recirculation and its resulting hot spot, in comparison with the case in absence of the AFU, can be suppressed. The results additionally concludes the extents to which the optimized airflow organization and temperature drop of the rack-level region (e.g., from the bottom towards the top of the rack unit) can be achieved with/without the AFU addition.
Sustainability Benefits Analysis of Cyber-Manufacturing Systems
Authors: Song Zhengyi , Moon Young 
Published: February 2021

Abstract
Cyber-Manufacturing System (CMS) is a vision for the factory of the future, where manufacturing processes and physical components are seamlessly integrated with computational processes to provide agile, adaptive, and scalable manufacturing services. Functional elements of CMS are digitized, registered, and shared with users and stakeholders through various computer networks and the Internet. CMS incorporates recent advances in the Internet of Things, Cloud Computing, Cyber-Physical System, Service-Oriented Technologies, Modeling and Simulation, Sensor Networks, Machine Learning, Data Analytics, and Advanced Manufacturing Processes. CMS possesses intelligence such as self-monitoring, self-adjustment, self-prediction, self-allocation, self-configuration, self-scalability, self-remediating, and self-reusing.
Such intelligent capabilities enable CMS to contribute to manufacturing sustainability. However, prior studies are limited in addressing a narrow scope of CMS or in covering only a subset of sustainability dimensions. This paper addresses the research gap by developing a holistic CMS infrastructure and adopting a Distance-to-Target based sustainability assessment approach to measure the sustainability benefits of CMS. To illustrate how the infrastructure and metrics are used to analyze the sustainability benefits of CMS, an example case is presented. The results show that CMS can deliver substantial sustainability benefits through increased productivity, profitability & energy efficiencies, and reduction of working-in-process (WIP) inventory levels & logistics costs.
The Influence of a Non-Aligned Semi-Elliptical Embedded Crack on the Stress Intensity Factor Distribution Along the Front of a Quarter-Circle Corner Crack in a Semi-Infinite Plate Under Pure Bending
Authors: Levy Cesar , Ma Qin , Perl Mordechai 
Published: February 2021

Abstract
Fitness-for-Service codes require whether non-aligned cracks be treated as coalesced or separate multiple cracks. The authors previously reported on the effect between an corner and an embedded parallel crack in 2-D and in 3-D scenarios subject to tensile loading. Since realistic crack configurations detected using non-destructive methods are generally 3-D in nature, the study of 3-D effect under different loading types is deemed necessary in order to obtain more practical guidance. In this study, we investigate stress intensity factors (SIFs) along the crack front of a quarter-circle corner crack when affected by a semi-elliptic surface crack in a semi-infinite large solid under pure bending. While keeping constant the geometry of the quarter-circle corner crack, the SIFs along its front are studied for a wide range of geometrical configurations of the surface crack by varying its ellipticity b1/a1 = 0.1∼1; the relative crack size of the two parallel cracks a1/a2 = 1/3∼2; the normalized vertical gap, H/a2 = 0.4∼2; and the normalized horizontal gap, S/a2 = −0.5∼2 between the two cracks on using linear elastic fracture mechanics (LEFM). The results from this study are collectively significant to the understanding of the correlation between the criteria and standards in Fitness-for-Service community and the consequence of their usage in engineering practice.
Effect of Cutting Environments on Drilling Induced Damage in GFRP Nanocomposites
Authors: Kishore Kumar Panchagnula , Jayaprakash Sharma Panchagnula 
Published: February 2021

Abstract
Drilling is most commonly used secondary machining process for structural joining of Glass Fiber Reinforced Plastic (GFRP) composites. Performing drilling operations on GFRPs/Multi-Walled CarbonNanoTubes (MWCNTs) reinforced GFRPs is really a challenging task due to their non-homogeneity and anisotropic behavior, which directs to generation of material damages. The prime focus of current work is to identify the suitable process parameters for enhancing the performance of drilling of GFRP nanocomposites. In this study, the drilling experiments are conducted on 0.3wt.% MWCNT-GFRP nanocomposites with solid carbide, TiCN and TiAlN coated drills (6mm diameter) under dry and chilled air cutting environments. The dry drilling experiments are conducted without any assistance of cooling fluid in ambient condition. The chilled air at a temperature of 3°C was supplied from the vortex tube. Experimental data is used for ANOVA (balanced) analysis. The cutting parameters such as feed rate, cutting speed and tool type (coating) are considered as input and the measured thrust force, delamination factor and AE RMS signal are treated as output responses. From ANOVA results, it is observed that the influence of feed rate is more on thrust force as compared to cutting speed. The coefficients of determination (R2) shows good fit between thrust force and cutting parameters and the corresponding confidence levels are above 98% for all cutting environments. Similarly, R2 values of delamination factor and AE RMS signals are above 90% and 96% respectively. The minimum thrust force and torque values are noted as 12.61 N and 0.152 N-m respectively at lower feed rate (10 mm/min) and higher cutting speed (1500 RPM) using TiCN coated drill under chilled air cutting environment. The delamination factor is also low (1.025) under the same cutting conditions of minimum cutting forces. A good correlation exists between the thrust force vs. delamination factor (&gt; 0.85) and the delamination factor vs. AE RMS signal (&gt; 0.80) for the selected cutting environments. The recommended range of RMS voltage is 0.083 to 0.121 volts for producing the delamination free holes on GFRP nanocomposites.
A Novelty Detection Approach to Compressor Valve Fault Detection and Localization
Authors: Scott Colton M. , Kolodziej Jason R. 
Published: February 2021

Abstract
Presented in this paper is the development of a vibration-based novelty detection algorithm for locating and identifying valve wear within industrial reciprocating compressors through the combined use of time-frequency analysis, image-based pattern recognition, and one-class support vector machines. A commonly reported cause of valve wear-related machine downtime is wear in the valve seat, causing a change in flow profile into and out of the compression chamber. Seeded faults are introduced into the valve manifolds of the ESH-1 industrial compressor and vibration data collected and separated into individual crank cycles before being analyzed using time-frequency analysis. The result is processed as an image and features used for classification are extracted using 1st and 2nd order images statistics and shape factors. A one-class support vector machine learning algorithm is then trained using data collected during healthy operation and then used to both detect and locate anomalous valve behavior with a greater than 82% success rate.