bluuebunny/crossref_metadata_2025 huggingface dataset:
A Numerical Investigation of the Effects of Structural Properties on the Performance of a Two-Section Porous Medium Burner
Authors: Rahimi Borujerdi P. , Akbari Hadi
Published: January 2020

Porous media combustion is a feasible approach to tackle challenges encountered in free flame burners by offering advantages such as lower pollutant emissions, higher flammability limits and better flame stabilization. This study computationally investigated the premixed combustion of a methane/air mixture in a porous medium burner. The porous medium consisted of two sections: The upstream one was called the preheating section; The downstream one was called the combustion section. For methane oxidation, GRI 3 mechanism including 53 species and 325 reactions was used. After a successful validation against the experiments, a baseline study was conducted. Furthermore, a parametric study was performed to illustrate the effects of the structural properties of the combustion section on the burner performance. Increasing the pore density decreased the temperature difference between the gas and the solid phases. Consequently, a burner with higher pore density in the combustion section exhibited less emissions. When the porosity of the combustion section increased, the gas phase temperature also increased but the solid phase temperature remained virtually unchanged for the porosity values studied. As a result, higher pollutant emissions were observed at the burner outlet. Finally, it was noticed that when the combustion section was elongated, both phases gained higher temperatures and while CO emission decreased, NO emission increased.
Automotive Laminated Side Glazing Rollover Performance When Subjected to Roadway Abrasion and Occupant Loading
Authors: Phillips Donald R. , Batzer Stephen A.
Published: January 2020

Destructive testing of commercial automotive movable laminated side glass was conducted to document the occupant retention characteristics of this glazing system in quarter-roll crashes with a prolonged slide distance. That is, in some overturns a vehicle will slide to a halt on its side with a window adjacent both to an occupant’s position and to the moving roadway. It is known by field experience that this situation can result in injurious ejection of the occupant through the adjacent window if the window is constructed of tempered glass and the window has fractured. When tempered glass fractures, the window disintegrates and fully opens the portal. With the laminated side glazing that is used on some passenger vehicles, fracture of the inboard and outboard glass plies will not necessarily cause the “sandwiched” PVB interlayer to be compromised. This PVB interlayer allows the glass plies to remain in place and resist the sliding interaction. This diminishes the ejection hazard that is associated with tempered side glass. The three drag tests described within this technical paper used a single model of sport utility vehicle driver’s position door and factory installed laminated side door glass. The testing replicated the interaction of the exterior surface of the laminated glass against the moving roadway while the glazing was pre-fractured and the interior glass ply was subjected to significant simulated occupant loading. These conditions ensured contact of the exterior glass ply against the moving abrasive roadway. The detached and slightly modified driver’s door was pulled at near highway speed over a substantial distance against abrasive asphalt, simulating a rollover accident with the side of the vehicle sliding to halt. The results of these tests show that the exterior surface of the glazing, primarily consisting of the hard ceramic SiO2, is sufficiently wear resistant and durable to wear but not rupture or pull out of the peripheral channel. This testing shows that laminated glass is the superior glazing material for this accident mode from an occupant containment perspective.
Steering Options for Maneuvering a Particle on a Surface
Authors: Hennessey Michael P. , Olson Derek A. , Shakiban Cheri
Published: January 2020

We consider the general problem of steering an infinitesimal propelled and steerable particle with no rotational inertia traversing on a mathematically smooth (vs. frictionless) surface, where both the speed and body yaw rate serve as inputs to the system and lateral motion is not allowed, i.e. through a no sideslip condition. More specifically, focus is on derivation of relevant state equations in control input form, numerical and visual confirmation of state equation accuracy through specific simulations, and exploring interesting approaches to nonholonomic path planning with associated numerical simulation and visualization. Given the state equations (3rd order), in the interests of practical validation, they were exercised by considering motion on a number of smooth surfaces. The surfaces were selected for a variety of reasons, such as: the resulting qualitative trajectory is known a priori, there exists an opportunity to check numerical results with respect to previous results, or the surfaces are iconic and/or are geometrically rich.

Nonholonomic steering on the surface is a very interesting and challenging problem and several approaches are investigated: (1) steering using sinusoids (detailed), (2) steering on a trajectory, and (3) “drive-and-turn” (valid in this case). Prior to implementing the steering using sinusoids algorithm, it was necessary to transform the system into “one-chained” form. The first step entailed conversion to an approximate one-chained form model that possesses a certain structure, from which the process established by Murray and Sastry can be successfully launched, where two special smooth scalar functions of the states are sought that possess special relationships to Lie-related distribution spaces associated with the control input vectors. Inputs are then transformed as well via specialized Lie derivatives. It was demonstrated through simulation that steering to an arbitrary system state on a faceted surface can be accomplished with sinusoidal inputs in only one maneuver set (i.e. maneuver A & B). Using this fact, the work presented culminates with steering to an arbitrary system state on a smooth surface that can be accomplished by essentially iterating on a steering algorithm that assumes the particle is on a plane tangent to the smooth surface at the desired destination. In this regard, it is shown that a sequence of maneuver sets converges rather quickly in the example demonstrated. Applications of this work pertain to the fairly general situation of steering a vehicle on a smooth surface, a practical vehicle navigation and control problem.
Computational Fluid Dynamics Modeling of a Heat Pipe Evacuated Tube Solar Collector Integrated With Phase Change Material
Authors: Pawar Vivek R. , Sobhansarbandi Sarvenaz
Published: January 2020

The increase in greenhouse gas and other global warming emissions makes it necessary to utilize renewable energy sources such as solar energy with high potential for heat production by means of solar thermal collectors. Among various types of solar collectors, evacuated tube solar collector (ETC) has attracted many attentions specially for the application in solar water heater systems (SWHs). However, due to the intermittence in solar intensity during the day, the ETCs may not work at their maximum functionality. There are number of studies investigating the effect of energy storage materials to eliminate the mismatch between supply and demand during peak hours. In the recent work of the authors, application of phase change materials (PCMs) integrated directly within the ETCs is studied experimentally. In this study, the computational fluid dynamics (CFD) modeling of heat pipe evacuated tube solar collector (HPETC) is performed. In order to cross-validate the obtained results to the recent experimental analysis, the boundary conditions are set as the real field-testing data. In the first part of the study, the 3D model of commercially available HPETC is simulated, while in the second part the HPETC integrated with the PCM is developed to analyze the improved thermal distribution. The selected type of PCM is Tritriacontane paraffin (C33H68), with a melting point of 72 °C and latent heat capacity of 256 kJ/kg. The simulation results show a acceptable agreement between the CFD modeling and the experimental data. The results from this study can be the benchmark for efficiency improvement of the ETCs in thermal energy storage systems.
Analysis of Structural Acoustic Design Variables for a Periodically Stiffened Plate Using the Finite Element Method
Authors: Blochberger Joseph A.
Published: January 2020

Investigating the acoustic radiation of stiffened plate structures is significant to the advancement of aircraft, automobile, and marine vehicle design. Plate and stiffener design variables affect how the global structure vibrates and radiates sound. The objective of this paper is to provide insight into how sensitive a periodically stiffened plate radiates sound in air with respect to its design variables.

This paper examines a clamped plate that is periodically stiffened along one direction. Finite element analysis is used to quantify the structural acoustic behavior of the plate subject to a harmonic point load at the plate’s center. Fourier transforms are performed along the plate’s surface to reveal the wavenumber content of the plate. Lastly, radiated sound power from the plate surface is computed.

A baseline plate without stiffeners is used for finite element modeling validation. Next, periodically spaced beams used for plate stiffening are inserted and varied in thickness. In addition, the plate thickness is also varied. Varying the plate thickness and the stiffener thickness provides insight to each design variable’s contribution to vibration and radiated sound power. The quantified findings from these parametric case studies serve as an insight into the structural acoustic performance of periodically stiffened structures.
Steam Turbine Axial Exhaust Diffuser Investigation Using a Test Rig and its Numerical Model
Authors: Kalista Robert , Mrózek Lukáš , Sláma Václav , Sedlák Kamil
Published: January 2020

Exhaust casings are one of the most important steam turbine components. The main purpose of the exhaust casing is to increase the last stage enthalpy drop, which results in an increase of the whole turbine output. It plays a significant role especially in turbines with lower outputs and in turbines whose condenser is cooled by air. In such cases, the exhaust casings with an axial diffuser is usually used. This paper deals with the investigation of the axial diffuser outlet part based on experimental measurements performed on a test rig installed in a wind tunnel in the Doosan Skoda Power laboratories and numerical simulations. The first part of the paper is about the general issues appearing the exhaust diffusers. Then, the design of the experimental test rig which aim is to simulate the flow conditions in real turbines is described. The last part of the paper is about experimental measurement as well as numerical results. The main observed phenomenon which is the effect of the circumferential angle on the inlet of the diffuser is described on different designs which were tested from the static pressure recovery factor point of view. For measuring flow parameters, a static wall pressure measurement was used together with multi-hole pneumatic probes. For numerical simulations, the commercial code ANSYS CFX 18.2 was used.
Performance of an Integrated Mild/Partial Gasification Combined (IMPGC) Cycle With Carbon Capture in Comparison With Other Power Systems
Authors: Long Henry A. , Wang Ting
Published: January 2020

With rising concerns about potential CO2 emissions and the effects of which on climate change and ocean acidification, it becomes necessary to consider developing newer and cleaner power plant technologies, including carbon capture. A conceptual clean coal technology called the Integrated Mild/Partial Gasification Combined (IMPGC) cycle implemented with a post-combustion carbon capture process is introduced in this paper. The IMPGC cycle employs mild gasification to preserve the high energy volatile matters within the coal and partial gasification to supplement the steam bottom cycle with a purely char-fired PC plant boiler. The performance of this newly conceptualized model is compared to those of other types of power plants, including natural gas combined cycle (NGCC), integrated gasification combined cycle (IGCC), and pulverized coal (PC) Rankine cycle plants under the condition that all plants utilize carbon capture in some form so as to achieve the same overall CO2 emissions as a high-performing NGCC plant. The results show that, while natural gas is still the top-performing power plant, IMPGC with carbon capture has the highest performance of all coal plants studied (∼39.7%), able to achieve the same CO2 emissions as natural gas, but with the same efficiency as a top-of-the-line subcritical Rankine cycle plant without carbon capture. This is about 2.5 percentage points better than an IGCC plant with carbon capture, ∼8 percentage points better than an ultra-supercritical Rankine cycle plant with carbon capture, and over 9 points better than a subcritical plant with carbon capture. This high performance is achieved through the use of a warm gas cleanup process based on the technology developed by RTI with the support of the U.S. Department of Energy.
Dynamic Characterization and Modeling of Flexure Based Planar Mechanism
Authors: Warnix Trevor , Tekes Ayse , McFall Kevin , Tekes Coskun
Published: January 2020

This paper investigates design, modeling and fabrication of a flexible five bar mechanism, which incorporates large deflecting flexure hinges attached to rigid links. This 3D printed flexible robotic mechanism is actuated by two servo motors and machine vision is used to obtain its tip position information. Detection of parts accomplished using color thresholding of a dynamic region of interest, while the position of detected elements is measured using the pinhole camera model. Under the assumption of non-small length flexures, where low aspect ratio is not satisfied, we adopt an initially curved pseudo rigid body approach to model each flexure as two rigid links that are pinned on top of each other using torsional springs, which capture the load-deflection behavior of the compliant flexures. Kinematic and dynamical equations are derived using both vector closure loop equations and Euler’s Laws of Motion. Adams simulation is performed by exporting the CAD model as a parasolid file, defining revolute joints and input motions and converting the rigid body to flexible. Mathematical model is validated using both the experimental data and Adams simulations.
Fracture Behavior of Cracked Ring Specimen at Different Crack Positions
Authors: Alqahtani Abdulmohsen M. , Albulayhid Thamer K. , Alotaibi Mutlaq N. , Alarifi Ibrahim M. , El-Bagory Tarek M. A. A.
Published: January 2020

The previous research review of piping systems revealed that the plastic pipes companies suffered from many problems in natural gas pipeline systems. One of the most significant problems appeared in the piping systems are external cracks due to manufacturing processes, welding technique and installation processes. The principal goal of the present experimental study is to predict the crack growth behavior and energy release rate of cracked ring specimen made from high-density polyethylene (HDPE) under different crack position angles and various crosshead speeds. The effect of loading rate on the external radial crack at different crack position angles plays an important role in the prediction of fracture behavior of plastic pipe materials. For this reasons, it is necessary to conduct a study for the fracture analysis of pipe ring specimen under tension loading with double external cracks at constant radial crack length to width ratio equal a/W = 0.5. Pre-cracking machine is designed especially in the present experimental study to simulate the actual radial cracks at outer surface of pipe ring specimens. The effects of crosshead speed and crack position angle are revealed a significant effect on the energy release rate and maximum applied load under tensile load.
Design, Modeling and Development of a Compliant Dual Resonator-Isolator
Authors: Jerkovic Boris , Rowell Abram , Ellis Nathan , Tekes Ayse
Published: January 2020

This paper investigates the construction, instrumentation, and dynamical modeling of a coupled three degrees of freedom compliant parallel arm mechanism. The compliant parallel arm, whose complete construction is carried out using 3D printing of polylactide (PLA) filaments, is a folded beam type mechanism, which is comprised of one primary and two secondary masses connected to two large deflecting beams. Dynamical model of the complete mechanism is obtained using Elastica Theory, where the large deflecting beams are considered as fixed-free cantilever beams subjected to a vertical tip load. Nonlinear load deflection curve, which is derived from the solutions of elliptical integrals, is approximated by a high-order polynomial function. Finally, the dynamics of the complete mechanism is derived using a classical lumped mass-spring-damper second order system. A linear actuator, PCB triaxial accelerometers, two laser displacement sensors and Arduino are utilized to gather acceleration and position information of each mass to identify the parameters of the lumped second order model using the offline Elastica Theory-based approach and polynomial fitting method. Numerical and experimental results verify the effectiveness of the proposed parameter identification schemes. Since system is nonlinear, state feedback linearization approach is adapted to linearize system equations at all operating points to control the trajectory of primary mass using a PID controller.
Numerical Investigation of an Academic Mistuned Bladed Disk Dynamics Accounting for Blade/Casing Contacts
Authors: Joachim Jeanne , Nyssen Florence , Batailly Alain
Published: January 2020

This contribution focuses on the combined analysis of mistuning and unilateral blade-tip/casing contacts. A 2D phenomenological finite element model of an aircraft engine fan stage is considered. It is reduced by means of the Craig-Bampton component mode synthesis method and contact treatment relies on a Lagrange multiplier algorithm within an explicit time-integration scheme. Blade-tip/casing contacts are initiated through the deformed shape of a perfectly rigid casing. Mistuning is accounted for on the blades only. Monte Carlo simulations are carried out in both linear and nonlinear configurations, which allows to compare amplifications predicted in both context due to mistuning. Following a thorough convergence analysis of the proposed numerical strategy, the influence of mistuning level as well as the configuration of the external forcing are investigated. Presented results underline the detrimental consequences of mistuning in a nonlinear structural context, yielding even higher vibration amplifications than in a linear context. A cross-analysis between linear and nonlinear computations reveals that no correlation is found between linear and nonlinear amplifications which suggests that the effect of existing strategies to mitigate vibration amplifications within a linear context may not be suitable within a nonlinear context.
Heating Conservation Methods and Economy Analysis of Winter Heating in Rural Residential Buildings in Southeast China: A Case Study
Authors: Tu Rang , Liu Mengdan , Liu Lanbin
Published: January 2020

In this paper, energy conservation approaches for residential buildings in rural area of southeast China are studied. There used to be no heating habits in rural buildings of southeast China, which is due to the relatively warm weather in winter. However, as the stand of living is increasing, heating in winter has become more popular in recent years. It is quite important to choose proper heating conservation materials taking both initial cost and operating cost into consideration. In this paper, a typical house in southern part of Henan Province is selected for study. It is a two-level house made of bricks, which was built in 2014. A set of radiators were installed for heating in winter. Water, which is heated by electrical heater, is used as heating medium for these radiators. As compared with heat pumps, draft sensation problem is avoided and temperature in the heating space is more uniform. However, operating fee is very high, which makes this heating method less attractive. To reduce power consumption of winter heating, heating load needs to be reduced and the efficiency of heating equipment needs to be increased. In this study, researches are carried out as following. First, a model is built in DeST, which is a software that can calculate hourly heating load and room temperature. Then, the effect of thermal preservation quality of envelops on room temperature and heating load are investigated. Six models with different envelopes are simulated. Then, heating load as well as power consumptions of electrical heaters and heat pumps among the six envelopes are compared. Lastly, economic analysis is carried out for the energy efficient retrofit case so that the payback period is calculated. The results show that heating load capacity of case F, envelope of which made of 240 bricks plus foamed plastic and hollow glass windows, can be reduced to 1/3 that of case A, envelope of which made of 240 bricks and single glass windows. Considering power consumptions of both compressors and fans, energy consumption density (divided by area) can be reduced from 21.6∼25 kWh·m−2·year−1 of case A, which has the worst heat conservation property, to 6.7∼7.7 kWh·m−2·year−1 of case F. If the building is improved from case A to case F and heat pumps are adopted, the payback period is 3.3∼3.8 years. Because of high cost of window retrofit and small influence of its heat conservation property on the reduction of heating capacity, it is recommended to just improve walls. Air tightness of window is more effective than thermal quality.
Numerical and Experimental Analysis of Attaching-Mandrel Process Under Multi-Pass Cold Spinning Process on Superalloy GH3030
Authors: Zixuan Li , Xuedao Shu , Zewei Cen , Song Zhang
Published: January 2020

The superalloy products formed by multi-pass conventional spinning are widely used in rotary forming parts with complex shapes. As the connection of each forming pass, the attaching-mandrel process has an important influence on forming quality and production efficiency. The hot spinning process is usually adopted in superalloy forming because its poor plasticity in normal temperature, meanwhile, it brings the poor surface quality of the parts and huge energy consumption. For this reason, the cold spinning and the attaching-mandrel process of nickel-base superalloy GH3030 are studied. The combination method of experiment and simulation is used to study the attaching-mandrel process based on one-forward-pass spinning process. The effects of pass pitch and the attaching-mandrel velocity on the tool forces, parts stress field, strain field and wall thickness distribution are analyzed. The microstructure of the part is divided into three layers: outer, middle and inner layer. The grain size of each layer is compared. Then the effect of different pass pitch on the grain structure is clarified. The results show that the reasonable pass pitch and the attaching-mandrel velocity can improve the forming quality and production efficiency. The multi-pass cold spinning process on superalloy GH3030 is feasible. The excessive pass pitch can cause seriously grain elongation, the grain boundaries are blurred, and even cracking.
Numerical Investigation of the Dropwise Condensation Process in Top of the Line Corrosion
Authors: Mohamed Ibrahim E. , Thompson Harvey M. , Barker Richard
Published: January 2020

Many approaches have been used for modelling Top of Line Corrosion (TLC) however there are a large discrepancies between their results. One common assumption is that TLC is limited by the amount of iron that can be transported with the condensed water. This means that the TLC rate is proportional to the water condensation rate and the iron solubility in the condensed phase. Therefore, a theoretical investigation is performed into the effects of gas inlet conditions on the water condensation rate in wet gas pipeline using Fluent. Comparisons were drawn with the semi-analytical model of Zhang et al. and CFD results showing good agreement between the two. The numerical results obtained reveal quantitatively how an increased inlet gas pressure leads to reductions in the condensation rate. While increasing inlet gas temperature and velocity lead to increases in condensation rate.
A Secure Cyber-Manufacturing System Augmented by the Blockchain
Authors: Song Jinwoo , Moon Young B.
Published: January 2020

Cyber-Manufacturing System (CMS) is an innovative factory of the future, where manufacturing information is being constantly exchanged among many entities through various computer networks including the Internet. However, CMS ushers in the unique security challenges from the sheer volume and pervasiveness of exchanged data, and increased accessibility of the system by its outsiders and insiders. Also, the connections among the physical components can reveal accessible routes into the system.

This research presents a unique approach to secure CMS augmented by a Blockchain. The secure Cyber-Manufacturing System with Blockchain consists of four layers: User layer, Provider layer, Service layer, and Blockchain layer. To validate how the system enables safe communications in CMS, auditing physical data through the private blockchain was experimented on a CMS testbed. The results of three different physical data audits are compared; the system’s effectiveness is demonstrated.
Boundary Integral Equations Method in the Coupled Theory of Thermoelasticity for Porous Materials
Authors: Svanadze Merab
Published: January 2020

This paper concerns with the coupled linear theory of thermoelasticity for porous materials and the coupled phenomena of the concepts of Darcy’s law and the volume fraction is considered. The system of governing equations based on the equations of motion, the constitutive equations, the equation of fluid mass conservation, Darcy’s law for porous materials, Fourier’s law of heat conduction and the heat transfer equation. The system of general governing equations is expressed in terms of the displacement vector field, the change of volume fraction of pores, the change of fluid pressure in pore network and the variation of temperature of porous material. The fundamental solution of the system of steady vibration equations is constructed explicitly by means of elementary functions and its basic properties are presented. The basic internal and external boundary value problems (BVPs) of steady vibrations are formulated and on the basis of Green’s identities the uniqueness theorems for the regular (classical) solutions of the BVPs are proved. The surface (single-layer and double-layer) and volume potentials are constructed and their basic properties are established. Finally, the existence theorems for classical solutions of the BVPs of steady vibrations are proved by means of the boundary integral equations method (potential method) and the theory of singular integral equations.
Computational Design Optimization of PCM-Based Attenuator of Fluid Temperature Fluctuations
Authors: Klimeš L. , Kozubík L. , Charvát P.
Published: January 2020

A fluid-PCM heat exchanger (attenuator) of a circular design with water as the fluid was investigated both numerically and experimentally. A computational model of the PCM-based attenuator was developed with the use of the control volume method and the effective heat capacity. Square wave fluctuations of the water temperature at the inlet of the attenuator were considered in the study. The model and its functionality was validated by means of experimental data. The experimental investigation was carried out in a lab environment and two tanks containing water of different temperatures with the computer-controlled mixing valve were used to simulate square wave temperature fluctuations. The validated model was then coupled with metaheuristic optimization methods. The bee algorithm, the genetic algorithm, and the particle swarm optimization algorithm were applied in the study. Design optimization of the attenuator was performed with the aim to maximize the attenuation capability of the attenuator, but considering a cost factor as well. Results indicated that the metaheuristic approach represents a viable way for the solution of this kind of problems. All three metaheuristics provided comparable results in terms of the value of objective function as well as of the computational efficiency.
Determination of the Optimal Range of the Compressor Inlet Air Temperature in a Power Plant With Stig Cycle Through of Advanced Exergetic Analysis
Authors: Barreto D. , Fajardo J. , Campillo J.
Published: January 2020

Conventional exergy analysis identifies the more inefficient components; however, this doesn’t regard interaction between components, neither real improvement potential to each component of the system, this information is providing for the advanced exergy analysis. In this paper was developed an advanced exergy analysis to determine the optimal range of the compressor inlet air temperature, to compensate the power loss in a power plant with Stig cycle and an air cooling system. This plant without cooling system at ISO conditions produce 52 MW, while in local conditions (32 °C, 80%RH) its productions decreases to 44.3MW. The results showed that for every degree centigrade that the air temperature decreases at inlet compressor the power output increases in 0.17 MW and total destroyed exergy increases 0.23 MW. It was determined that for the optimal range of compressor inlet air temperature is between 10 and 12°C; at this range were obtained the highest power output values, and the values of the avoidable and endogenous exergy destroyed are diminished in 0.28 MW and 0.20 MW respectively compared to those given in local operating conditions.
Evaluation of Thermal Effects in Turning Processes: Numerical and Experimental Approach
Authors: Kolluri Aruna Prabha , Balla Srinivasa Prasad , Paruchuru Satya Prasad
Published: January 2020

The 3D Finite element method (FEM) is an efficient tool to predict the variables in the cutting process, which is otherwise challenging to obtain with the experimental methods alone. The present study combines both experimental findings and finite element simulation outcomes to investigate the effect of tool material on output process variables, such as vibrations, cutting temperature distribution and tool wear mechanism. Machining of popular aerospace materials like Ti-6Al-4V and Al7075 turned with coated and uncoated tools are part of the investigation. The authors choose the orthogonal test, measured vibrations and cutting temperatures and used FE simulations to carry out the subsequent validations. This study includes the influence of the predicted heat flux and temperature distribution on the tool wear mechanism. The main aim of this study is to investigate the performance quality of uncoated and coated carbide tools along with its thermal aspects. Comparison of experiment and simulation outcomes shows good agreement with a maximum error of 9.02%. It has been noted that the increase of cutting temperature is proportional to its cutting speed. As the cutting speed increases, it is observed that vibration parameter and flank wear value also increases. Overall, coated carbide turning insert tool is the best method for metal turning with higher rotational speeds of the spindle.
Influence of Fractional Flow Reserve Setting on the Procedure Precision
Authors: Abuouf Yasser , Ookawara Shinichi , Ahmed Mahmoud
Published: January 2020

Coronary artery disease is the progressive narrowing (stenosis) of the heart supply arteries. Heart attack could occur as a consequence of severe blockage in the artery. A definitive diagnosis of its severity is of great importance for physicians to decide the best treatment plan. Fractional flow reserve (FFR) is a procedure that adopts a sensor tipped guidewire to measure upstream and downstream pressures of the stenosis. It is considered the most accurate method to pinpoint the stenosis severity. In this procedure, the centerlines of the guidewire and blood vessel should be aligned together. Due to the long distance between its insertion point and the stenosis, a possible inclination of the guidewire can occur. The aim of the present study is to investigate the effect of guidewire inclination on pressure measurements. Three different degrees of severity are modeled with placing the guidewire at different inclination angles. Continuity and momentum equations of blood flow are stated and computationally simulated. Comparisons between calculated and available measured values show a good agreement. The ratios between pressure drop and distal dynamic pressure (CDP), and between pressure recovery coefficient and the area blockage (η) are calculated. The predicted results for each case are compared with the control case (without guidewire) and analyzed. The results aid in improving the FFR accuracy in diagnosis of stenosis severity.
A New Composite Phase Change Material for Thermal Energy Storage
Authors: Su Che-Fu , Xiang Xinrui , Esmaeilzadeh Hamed , Wang Jirui , Fratto Edward , Charmchi Majid , Gu Zhiyong , Sun Hongwei
Published: January 2020

Enhancing the thermal conductivity of phase change materials (PCMs) is attracting attention for renewable energy applications such as solar, geothermal and wind energy. The use of energy storage can significantly improve the efficiency of renewable energy systems due to their intermittent nature. Latent heat thermal energy storage is a particularly attractive technique due to its high capacity can store energy at near constant temperature corresponding to the phase transition temperature of the PCMs. The present work aims to overcome this undesirable property of low thermal conductivity by manipulating metal fillers including nickel (Ni) nanoparticles/nanowires within the paraffin wax to improve its thermal property. In present work, a finite element method (FEM) was developed to obtain a fundamental understanding of the behavior of the Ni particles/wires under a uniform magnetic field by predefined magnetic pads. In the model, the Navier-Stokes equations were introduced as governing equations for the fluid field and the magnetic field was simulated by Maxwell’s equations. Then the motion of single Ni wire was modeled and the translation and rotational movements of the wire was studied in this paper.
A Quaternion-Based Sliding Mode Observer for Gyro-Bias Estimation and Attitude Reconstruction
Authors: Tian Yuan , Compere Marc , Drakunov Sergey
Published: January 2020

Localization accuracy is one of the most important parts of Unmanned Vehicle Systems, Automated Vehicles, Robotics and Navigation. The 6-DOF Inertial Measurement Unit (IMU) is a commonly used device for inertial navigation and is composed of a 3-axis accelerometer and 3-axis gyroscope. The body-fixed IMU measurements are combined with initial values to produce a position and orientation estimate in the inertial frame with every new measurement. However, IMU performance is greatly degraded by bias, scale-factor, non-orthogonality, temperature, and noise. This paper develops a sliding mode observer specifically focused on gyroscope bias estimation to improve gyro measurement results. The work presented here improves the performance of tilt sensors equipped in a commercially available smartphones with accelerometers and gyroscopes. The algorithm uses quaternions to avoid the well-known Euler angle singularities also known as gimbal lock. The observed gyro-bias can be used to reconstruct an improved estimation of the real attitude. A sliding-mode observer was constructed, and A* Matrix stability criterion were used to guarantee observer error convergence in finite time. The algorithm was verified using both a simulated IMU model and experimental tests with a custom designed rotational platform. Simulation tests used a predefined gyros-bias to ensure the algorithm-estimated results converged to the correct value. Simulation results show the observer error quickly converges to zero and the gyro-bias estimation converged to the expected values. The results also show that the proposed method is very effective for reconstructing the real attitude using the observed gyro-bias. This study presents a fast, simple gyro-bias estimation method that can help reconstruct the real attitude with a simple formulation that eliminates complicated constraints.
Analysis of Combined Electroosmotic and Pressure Driven Flow of Multilayer Immiscible Fluids in a Narrow Capillary
Authors: Escandón Juan P. , Torres David A.
Published: January 2020

This paper presents the analytical solution of a combined electroosmotic and pressure driven flow of multilayer immiscible fluids in a narrow capillary. The mathematical model is based in the Poisson-Boltzmann equation and the modified Navier-Stokes equations. In the steady-state analysis, we consider different conditions at the interfaces between the fluids as potential differences, surface charge densities and electro-viscous stresses balances, which are discussed in detail. Results show the transport phenomena coupled in the description of velocity distribution, by the analyzing of the dimensionless parameters obtained, such as: potential differences, surface charge densities, electrokinetic parameters, term involving the external pressure gradient, ratios of viscosity and of dielectric permittivity. Here, the presence of a net electric charges balance at the interfaces breaks the continuity of the electric potential distributions and viscous shear stresses, modifying the flow field; thus, the electrical conditions established at the interfaces play an important role on the flow behavior. The present work, in which the velocity field is described, aims to be an important contribution in the development of theoretical models that provide a better understanding about labs-on-a-chip design.
Investigation of Heat Transfer Characteristics of Supercritical Carbon Dioxide at Microchannels
Authors: Asadzadeh Mostafa , Parahovnik Anatoly , Adeoye Stephen , Peles Yoav
Published: January 2020

Carbon Dioxide (SCO2) can revolutionize the thermal management landscape due to a dramatic increase in enthalpy and a specific heat near supercritical state, particularly along the pseudocritical line, which correspond to much lower temperatures and pressures than water and other refrigerants. This study is conducted to assess the capability of supercritical CO2 in heat transfer applications. The heat transfer coefficient of carbon dioxide near the pseudocritical conditions was experimentally studied at the micro scale. Devices with 20 micro channels were fabricated to measure local and average heat transfer coefficient as well as system pressure drop. The experimental results showed a significant increase up to 72000 W/m2.k in local heat transfer coefficient and large pressure drop up to 3 MPa at microscale with supercritical CO2.
The Influence Rule of Geometric Parameters on the Closure of Inside Cavity of the Skew Rolled Steel Ball by Floating Pressure Method
Authors: Shu Chang , Xia Yingxiang , Shu Xuedao , Tian Duanyang
Published: January 2020

Due to the impact of alternating tension-and-compression on the skew rolled steel ball, it is prone to generate the defects of cavity inside the steel ball. In order to eliminate this cavity, this paper applies the Floating-Pressure-Method (FPM) to handle this imperfection. The procedures of FPM are: putting the rolled steel ball into the floating pressure device, then increasing the air pressure on the steel ball and maintaining this pressure for some time, finally eliminating the undesired cavity inside the steel ball. The DEFORM-3D finite element software, is used for simulation of the void cavity inside the steel ball by applying the FPM conditions, then analyzing the diameter, shape and position of cavity as well as the numbers of cavities and so on, obtaining the influence rule of geometric parameters on the closure of inside cavity of the skew rolled steel ball by floating pressure method. The experiment of FPM shows that the cavity inside the steel ball can be closed effectively and the maintain high dimensional accuracy. The research results provide theoretical basis for reasonably determining the process parameters of FPM and improving the quality of rolling products.
Fundamental Study on Friction-Driven Gyroscopic Power Generator Works Under Arbitrary Vibration
Authors: Watanabe Aya , Yuyama Ryousuke , Hosaka Hiroshi , Yamashita Akira
Published: January 2020

This paper describes a friction-driven gyro generator that works under arbitrary vibrations and generates more than 1 W of power. Vibrational generators are energy harvesters that convert environmental vibrations into electrical power via the inertial force of pendulums. In conventional generators that use simple vibration, the power is less than 10 mW for a wearable size because vibrations in the natural environment are as low as 1 Hz. Gyroscopic generators increase the inertial force by rotating a pendulum at high speed and creating a gyro effect. In this generator, a palm-size product that generates 0.1 W and weighs 280 g has already been commercialized, but this device operates only under a particular vibration that synchronizes rotor precession and stalls under random vibration. To solve this problem, in this research, two gimbals and a precession spring are introduced to support the rotor. We developed a prototype generator with straight tracks measuring 16 cm × 11 cm × 12 cm with a mass of 980 g. Under a vibration of 4 Hz and ±20 degrees, power generation of 1.6 W was confirmed. Next, a prototype circular track was made. Power generation of 0.2 W with a vibration of 1 Hz and ±90 degrees was confirmed. Finally, a simple formula to estimate the upper limit of the generation power is derived. It is suggested that the circular-type generator is suitable for low-frequency vibration and can generate twice the power of a straight-type generator.
X-Ray Induced Acoustic Computed Tomography for Non-Destructive Testing of Aircraft Structure
Authors: Tran Tiffany , Samant Pratik , Xiang Liangzhong , Liu Yingtao
Published: January 2020

For decades, aircraft disasters have always been a concern for airline companies and especially for consumers. Scientists all over the world have been constantly trying to study, discover and invent new methods for testing and prevention to reduce future aircraft accidents. One of those methods is non-destructive testing, which is a widely adaptive process for analyzing structural integrity over wide arrays of object. X-rays, ultrasound and computed tomography (CT) are non-destructive testing applications commonly used for the commercial aircraft maintenance. These non-destructive testing methods for aircraft structures give us high-quality images of structural damage but, there are some disadvantages related to resolution and the contrast mechanism of the image. The goal of this study is to demonstrate the concept of X-Ray Induced Acoustic Computed Tomography (XACT) imaging method for defect detection and localization through simulations using k-wave MATLAB toolbox. XACT is a technique based on the X-ray induced acoustic effect. In XACT, a short pulsed of X-rays are required to achieve thermal response and generate acoustic waves. X-ray travels to an object, the photons are absorbed causing the temperature in the object to raise, which generates acoustic waves due to thermoelastic expansion. These acoustic waves are then detected by ultrasonic transducers. Within the fuselage of the aircraft, the aircraft’s stiffener is designed using SolidWorks. along with two different types of defects through voids due to manufacturing imperfection process. As well as, cracks in the surface of the model due to mechanical failures are created in MATLAB. Two properties of Aluminum 6065 and Inconel 625 materials were selected for our simulation study since it is often used for the fuselage and/or aircraft engines. XACT images are generated under the combination of high X-ray absorption and ultrasonic transducers that will be able to overcome the disadvantages of the X-ray imaging technique and ultrasound imaging technique in image resolution and contrast mechanisms. The results from this simulation study demonstrate that the XACT method not only gives us high-resolution images but moreover, higher contrast of images that also allows us to detect position accuracy of the cons created.
Time-Domain Spectral Element Simulation of Lamb Wave Time Reversal Method for Detecting a Breathing Crack in a Plate
Authors: Yu Zexing , Du Fei , Xu Chao
Published: January 2020

Lamb wave is considered as an appropriate approach to detect the cracks in structures. This paper combines an efficient time-domain spectral finite element with time reversal method to develop an efficient breathing crack detection method. In this regard, Gauss-Lobatto-Legendre quadrature rules and penalty function method are carried out to construct an effective and accurate approach. Comparing the computation scales and results of this method and traditional finite element method, the validity and superiority of the proposed model is stressed. The reconstructed signals of two scenarios, intact and impaired structures, are captured. It is concluded that, this approach is capable of detecting breathing cracks. In addition, the influences of the relative depth of the notch and incident region are studied. This research may provide the guidance for experiment configuration and the further study.
Multi-Material FDM 3D Printing Process Parameter Development Based on Bending Test Characterization
Authors: Lai Heather L. , Nelson Aaron
Published: January 2020

The purpose of this investigation is to study the effects of perimeter inflation on the dynamic behavior of a flexible / rigid multi-material interface. The results of this study can be applied to applications where there is a need for low cost, multi-material 3D printed parts which have both flexibility and strength at the material interfaces designed to undergo simultaneous axial strain and flexural strain.

A non-homogeneous 3D printed structure with the desired static and dynamic mechanical behavior was designed using a flexible thermoplastic polyurethane substrate (NinjaFlex) and stiff ABS segment. The multi-material part was printed using a consumer grade dual extruder desktop FDM 3D printer.

This project focused on the evaluation of the mechanical behavior of the 3D multi-material due to delamination at the interfaces between the materials undergoing simultaneous flexural and axial loading. In order to reduce the occurrences of delamination, overlap at the interfaces was imposed by using perimeter inflation of both the two different materials. The purpose of the project was to develop a test methodology for the evaluation of the use of perimeter inflation in order to improve the behavior of the multi-material fused deposition printed parts. A modified 3 point bending test was developed to measure the equivalent stiffness and internal damping of the material interface.

As a result of this testing, increasing the perimeter inflation was found to cause a modest increase in the stiffness of the interface, with little effect on the internal damping of the interface.