bluuebunny/crossref_metadata_2025 huggingface dataset:
Exergy Analysis-Potential of Salinity Gradient Energy Source
Authors: Emdadi Arash , Zenouzi Mansour , Lak Amir , Panahirad Behzad , Emami Yunus , Lak Farshad , Kowalski Gregory J.
Published: January 2018

Mixing of fresh (river) water and salty water (seawater or saline brine) in a controlled environment produces an electrical energy known as salinity gradient energy (SGE). Two main conversion technologies of SGE are membrane-based processes: pressure retarded osmosis (PRO) and reverse electrodialysis (RED). Exergy calculations for a representative river-lake system are investigated using available data in the literature between 2000 and 2008 as a case study. An exergy analysis of an SGE system of sea-river is applied to calculate the maximum potential power for electricity generation. Seawater is taken as reference environment (global dead state) for calculating the exergy of fresh water since the sea is the final reservoir. Aqueous sodium chloride solution model is used to calculate the thermodynamic properties of seawater. This model does not consider seawater as an ideal solution and provides accurate thermodynamics properties of sodium chloride solution. The chemical exergy analysis considers sodium chloride (NaCl) as main salt in the water of this highly saline Lake with concentration of more than 200 g/L. The potential power of this system is between 150 and 329 MW depending on discharge of river and salinity gradient between the Lake and the River based on the exergy results. This result indicates a high potential for constructing power plant for SGE conversion. Semipermeable membranes with lifetime greater than 10 years and power density higher than 5 W/m2 would lead to faster development of this conversion technology.
Retracted: “Residential Energy Efficiency Improvement Using Solar Heating of Water and Air: A Computational Study” [ASME 2017 International Mechanical Engineering Congress and Exposition, Volume 6: Energy, Tampa, Florida, USA, November 3–9, 2017, Conference Sponsors: ASME, ISBN: 978-0-7918-5841-7, Copyright © 2017 by ASME. Paper No. IMECE2017-70041, pp. V006T08A037; 7 pages; doi: 10.1115/IMECE2017-70041]
Authors: ASME
Published: January 2018

The above referenced paper has been removed from publication. (March 10, 2020)

Copyright © 2020 by ASME
Segmenting Fly Ash Particles Using Image Processing Techniques
Authors: Asmari Ali , Hoberock L. L.
Published: January 2018

Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with flue gases. In the US about 43% is recycled and is often used to supplement Portland cement in concrete production. Fly ash can improve the concretes mechanical properties and decrease cost. Depending upon the source and makeup of the coal being burned, the components of fly ash vary considerably. These variations affect the quality of the final product. Accordingly, it is important for cement manufacturers to know the amount and type of the components in these particles. The objective of this project is segmentation of images of fly ash particles acquired using a micro computed tomography (μCT) imaging device. A set of grayscale images is produced, with each image representing a particular slice of the particle. The desired segmentation operation should identify particles and label regions of a given image based on similarity, as perceived by human observers. In this paper, two techniques are proposed for segmenting different phases of material in these images. The first technique uses Contrast Stretching and Histogram Matching and is based solely on the gray scale value of the pixels in the image slices. In the second proposed technique, Circular Gabor Filters (CGF) are used to segment the regions with porous textures in the cross section of the particle. We have also proposed a technique for designing the CGF such that when applied to the gray scale images, the filter passes the porous regions of components accurately, while blocking non-porous regions. By combining these techniques, we have developed a program that is able to segment different types and regions of impurities in the cross sections of a fly ash particle and create 3D models of these particles, presenting the locations and sizes of different phases of material.
Comparison and Evaluation of Engine Performance, Emission, Noise and Wear of Diesel and Karanja Oil Methyl Ester Biodiesel in a 980HP Military Turbo Charged CIDI Engine
Authors: Pandey Anand Kumar , Nandgaonkar M. R. , Pandey Umang , Suresh S. , Deshmukh Vijay R.
Published: January 2018

Global warming due to engine exhaust pollution and rapid depletion of petroleum oil reserves, has given us the opportunity to find bio fuels as alternative to diesel fuel. Biodiesel is an oxygenated, sulphur free, non-toxic, biogradable and renewable fuel. Karanja biodiesel is prepared using Karanja oil and methanol by the process of transesterification. In the present study, a military 720 kW turbo charged, compression ignition diesel injection (CIDI) engine was fuelled with diesel and Karanja oil methyl ester (KOME) biodiesel respectively. These were subjected to 100 hours long term endurance tests. The performances of fuels were evaluated in terms of brake horse power (kW), torque, heat release rates and specific fuel consumption. The emission of carbon monoxide (CO), unburnt hydrocarbon (UHC), oxides of nitrogen NOx and smoke opacity with both fuels were also compared. Lubricating oil samples, drawn from the engine after 100 hours long term endurance tests, were subjected to elemental analysis. Atomic absorption spectroscopy (AAS) was done for quantification of various metal debris concentrations. Use of Karanja oil methyl ester (KOME) biodiesel in a turbo charged CIDI engine was found compatible with engine performance along with lower emission characteristics (UHC 70%, CO 85.6%), and exhaust noise 11.9% but 13.7% higher NOx emissions. Engine metals wear were found 32% lower for a KOME biodiesel operated engine.
Modeling of Moisture Diffusion Effect on Peel and Sheer Stresses in Adhesively Bonded Single Lap Joints Under Shear-Tensile Loading
Authors: Mazhari Emad , Nassar Sayed A.
Published: January 2018

In this study, the Fickian diffusion formulation is extended to the adhesive layer of a single lap joint model, in order to develop a coupled peel and shear stress-diffusion model. Constitutive equation are formulated for shear and peel stresses in terms of adhesive material properties that are time and location-dependent. Numerical solution is provided for the effect of diffusion on shear and peel stresses distribution. Detailed discussion of the results is presented.
Impact Localization on a Composite Plate With Unknown Material Properties Using PWAS Transducers and Wavelet Transform
Authors: Migot Asaad , Giurgiutiu Victor
Published: January 2018

In this work, an impact experiment on a composite plate with unknown material properties (its group velocity profile is unknown) is implemented to localize the impact points. A pencil lead break is used to generate acoustic emission (AE) signals which are acquired by six piezoelectric wafer active sensors (PWAS). These sensors are distributed with a particular configuration in two clusters on the plate. The time of flight (TOF) of acquired signals is estimated at the starting points of these signals. The continuous wavelet transform (CWT) of received signals are calculated with AGU Vallen wavelet program to get the accurate values of the TOF of these signals. Two methods are used for determining the coordinates of impact points (localization the impact point). The first method is the new technique (method 1) by Kundu. This technique has two linear equations with two unknowns (the coordinate of AE source point). The second method is the nonlinear algorithm (method 2). This algorithm has a set of six nonlinear equations with five unknowns. Two MATLAB codes are implemented separately to solve the linear and nonlinear equations. The results show good indications for the location of impact points in both methods. The location errors of calculated impact points are divided by constant distance to get independent percentage errors with the site of the coordinate.
Development of a Method of Calculation of Energy Balance in Exhaust Systems in Terms of Energy Recovery
Authors: Fuc Pawel , Lijewski Piotr , Ziolkowski Andrzej , Dobrzynski Michal
Published: January 2018

Energy balance of an engine is a distribution of heat supplied to the engine among the effective work and individual losses. The division of the total loss into constituent losses allows determining the influence of individual factors on the operation of engines under different conditions. The external energy balance of a combustion engine is mainly performed under laboratory conditions on engine dynamometers. In this method, a variety of parameters is measured, based on which individual energy losses are calculated such as fuel consumption, temperatures of the intake air and the exhaust gas, mass flow of the intake air and exhaust gas, inlet and outlet temperature of the coolant, mass flow of the coolant, engine speed and load. In order to determine the energy loss in the exhaust system, a new research method was proposed that, beside the measurement of the fundamental thermodynamic quantities, assumes utilization of modern measurement equipment such as portable measurement systems (PEMS) and engine dynamometers capable of reproducing actual driving cycles. The paper also presents the main assumptions of this method and the results of tests performed under actual operating conditions. The tests were carried out according to the RDE (Real Driving Emission) routines on PC (Passenger Cars), LDV (Light Duty Vehicles) and HDV (Heavy Duty Vehicles) vehicle categories fitted with spark ignition and diesel engines. Based on the above, the amount of exhaust gas energy in individual portions of the exhaust system was determined. Based on the obtained results, the potential for the application of energy recovery based on thermoelectric modules was presented. The areas of application of ATEG (Automotive Thermoelectric Generator) were specified. Simulation tests were carried out using tools based on CFD numerical fluid mechanics for heat exchangers of the proprietary ATEG generators.
An Experimental Study of Surfactant Effect on Gas Tolerance in Electrical Submersible Pump (ESP)
Authors: Zhu Jianjun , Zhu Haiwen , Zhang Jiecheng , Zhang Hong-Quan
Published: January 2018

An experimental study on ESP boosting pressure under air-water flow with/without surfactant injection is presented. The experimental facility comprises of a 3-inch-diameter stainless steel liquid loop and ½-inch-diameter gas loop. A radial-type ESP with 14 stages assembled in series was installed in the testing bench. Pressure ports were drilled at inter-stage to measure the stage-by-stage boosting pressure. Surfactants, isopropanol (IPA) were injected to change interfacial properties of working fluids. Experiments were carried out with mapping and surging test schemes to evaluate pump behaviors at different operational conditions. ESP pressure increment under single-phase water flow agrees well with manufacture curves. For mapping tests without surfactant injection, ESP performance suffers from a severe degradation as gas flow rate increases. High gas entrainment rate causes oscillations of liquid flow rate and pump boosting pressure. A sudden drop of ESP pressure increment, termed as pressure surging, occurs at the critical inlet gas volumetric fraction (GVF). At higher rotational speeds, the critical GVF is higher. With surfactant injection, ESP boosting pressure improves significantly. With different GVFs, only mild degradation was observed. Pressure surging phenomenon disappeared. Further, liquid flow rate and pump boosting pressure are more stable at high GVFs compared to experimental data without surfactant injection.
3D Printing of Medical Models: A Literature Review
Authors: Wei Xingjian , Zeng Li , Pei Zhijian
Published: January 2018

Medical models are physical models of human or animal anatomical structures such as skull and heart. Such models are used in simulation and planning of complex surgeries. They can also be utilized for anatomy teaching in medical curriculum. Traditionally, medical models are fabricated by paraffin wax or silicone casting. However, this method is time-consuming, of low quality, and not suitable for personalization. Recently, 3D printing technologies are used to fabricate medical models. Various applications of 3D printed medical models in surgeries and anatomy teaching have been reported, and their advantages over traditional medical models have been well-documented. However, 3D printing of medical models bears some special challenges compared to industrial applications of 3D printing. This paper reviews more than 50 publications on 3D printing of medical models between 2006 and 2016, and discusses knowledge gaps and potential research directions in this field.
Modeling and Simulation of 3-D Interfacial Cracks by XFEM
Authors: Pathak Himanshu , Singh Akhilendra , Singh Indra Vir , Zafar Sunny
Published: January 2018

The structural integrity of multi-layered material depends on the mechanical properties and the fracture behaviour at the interface. The sudden jump in mechanical properties across the interface is the major source of failure in layered materials. An accurate evaluation of mixed-mode SIFs becomes essential for safe design of layered structure components. In this work, extended finite element method (XFEM) has been used to analyze interfacial cracked three-dimensional structures under mechanical loading. In XFEM, partition of unity enrichment concept is used to model a crack e.g. a crack surface is modeled by Heaviside enrichment function whereas a crack front is modeled by branch enrichment functions. Discontinuity due the presence of bi-material interface is modeled by the signed distance function. Modified domain based interaction integral approach has been used to evaluate the individual stress intensity factors. Three-dimensional cylindrical domain having an interfacial crack is taken for the simulations. A comparative analysis has been performed with and without an interface for an embedded penny shape crack. The effect of material interface on the SIFs has been analyzed in detail. Finally, a three-dimensional interfacial crack growth simulation has been performed for arbitrary shape crack.
Robust Controller Design for Active Suspension Systems of Road Vehicles
Authors: Zhu Shenjin , He Yuping
Published: January 2018

The Linear Quadratic Gaussian (LQG) technique has been applied to the design of active vehicle suspensions (AVSs) for improving ride quality and handling performance. LQG-based AVSs have achieved good performance if an accurate vehicle model is available. However, these AVSs exhibit poor robustness when the vehicle model is not accurate and vehicle operating conditions vary. The H∞ control theory, rooted in the LQG technique, specifically targets on robustness issues on models with parametric uncertainties and un-modelled dynamics. In this research, an AVS is designed using the H∞ loop-shaping control, design optimization, and parallel computing techniques. The resulting AVS is compared against the baseline design through numerical simulations.
Measurements and Numerical Simulations of Heat Transfer and Pressure Drop in a Duct With Smooth Walls
Authors: Li Puxuan , Eckels Steve J.
Published: January 2018

Accurate measurements of heat transfer and pressure drop play important roles in thermal designs in a variety of pipes and ducts. In this study, the convective heat transfer coefficient was measured with a semi-local surface average based on Newton’s Law of cooling. Flow and heat transfer data for different Reynolds numbers were collected and compared in a duct with smooth walls. Pressure drop was measured with a pressure transducer from OMEGA Engineering Inc. The experimental results were compared with numerical estimations generated in ANSYS Fluent. Fluent contains the broad physical modeling capabilities needed to model heat transfer and pressure drop in the duct. Thermal conduction and convection in the three-dimensional (3D) duct are simulated together. Special cares for selecting the viscosity models and the near-wall treatments are discussed. The goal of the paper is to find appropriate numerical models for simulating heat conduction, heat convection and pressure drop in the duct with different Reynolds numbers. The relationship between the heat transfer coefficient and Reynolds numbers is discussed. Heat flux and inlet temperature measured in the experiment are applied to the boundary conditions. The study provides the unique opportunity to verify the accuracy of numerical models on heat transfer and pressure drop in ANSYS Fluent.
Synthesizing Precompressed Beams As Bistable Compliant Mechanisms
Authors: Siddiqui Mohammed Abdullah Maaz , Zhou Hong
Published: January 2018

Bistable mechanisms provide two stable positions. Input power is not needed to maintain any of the two stable positions. To switch from one stable position to another, input power is required. Bistable mechanisms have many applications including valves, closures, switches and various other devices. Unlike conventional rigid-body bistable mechanisms that rely on relative motions of kinematic joints, bistable compliant mechanisms take advantage of elastic deformations of flexible members to achieve two stable positions. There are two symmetric buckled shapes in a precompressed beam that has one fixed end and one pinned end. The two buckled shapes match the two stable equilibrium positions of bistable compliant mechanisms. The precompressed beam can be rotationally actuated at the pinned end to snap from one buckled shape to another. Synthesizing precompressed beams as bistable mechanisms is challenging because of buckling instability and integrated force and deflection characteristics. In this paper, the buckled shape is derived for a precompressed beam with fixed and pinned ends. The input torque at the pinned end is analyzed for a precompressed beam to snap between its two symmetric buckled shapes. Precompressed beams are synthesized as bistable compliant mechanisms through axial compression and beam thickness in this paper.
Numerical Study of Joule Heating Effect on Dielectrophoresis-Based Circulating Tumor Cell Separation
Authors: Aghilinejad Arian , Aghaamoo Mohammad , Chen Xiaolin
Published: January 2018

Insulator-based dielectrophoresis (iDEP) is known as a powerful technique for separation and manipulation of bioparticles, using arrays of insulating posts and external electrical field. In this research, we utilized numerical simulation to study, in detail, the Joule heating which is one the most important phenomena in iDEP technique specially related to bioparticles separation and manipulation in physiological samples. Although Joule heating has been observed in both electrode-based and insulator dielectrophoresis, its effect is more significant in iDEP since higher electric potentials are required in this technology. As a result of the external electrical field, the temperature gradients would create conductivity, permittivity, viscosity and density local gradients in the solution, and consequently cause bulk fluid forces and fluid motion, known as electrothermal flow (ET). These flow circulations can cause unpredicted behavior of the device and even cause problems due to clogging. Moreover, the temperature rise due to the Joule heating could threaten the cell viability. In this study, we are going to develop a robust numerical model for predicting the flow behavior in the existence of external electric field and determining the temperature and velocity profile which can determine the cell viability and clogging problem in iDEP microdevices. The developed numerical tool was used based on the properties of circulating tumor cells (CTCs) and White blood cells (WBCs) and their separation.
New Design Solution for Crankshaft
Authors: Al-Azirjawi Basheer Saad Kadhum
Published: January 2018

The crankshaft is a key part moving in the internal combustion engine. It converts the reciprocating piston movement into rotary motion. It is exposed to different forces resulted from the pistons pressures, friction, bending stresses and others. The paper concentrates on protecting the crankshaft journals from the direct impact of the piston pressure and other forces. It presents a familiar new modular product design. From this concept, work has done on the additional of the so-called ‘load bearing’ (two halves of a highly finished surfaces sleeve) embedded within the crankshaft journal. The proposed load bearing isolates the crankshaft journal and takes the place in the contact with other rotary components. This is an experimental research because of the presence of an extensive variety of models and uses of crankshafts. A prototype of the new solution was made and implemented on a single piston four stroke internal combustion engine and put in operation for 250 hrs. A precise examination and analyses of parameters in contrast with conventional crankshaft was done for verification and validation.
Development of Artificial Neural Network Based Design Tool for Aircraft Engine Bolted Flange Connection Subject to Combined Axial and Moment Load
Authors: Sanli T. Volkan , Gürses Ercan , Çöker Demirkan , Kayran Altan
Published: January 2018

Bolted flange connections are one of the most commonly used joint types in aircraft structures. Typically, bolted flange connections are used in aircraft engines. The main duty of a bolted flange connection in an aircraft engine is to serve as the load transfer interface from one part of the engine to the other part of the engine. In aircraft structures, weight is a very critical parameter which has to be minimized while having the required margin of safety for the structural integrity. Therefore, optimum design of the bolted flange connection is crucial to minimize the weight. In the preliminary design stage of the bolted flange connection, many repetitive analyses have to be made in order to decide on the optimum design parameters of the bolted flange connection. Two main methods used for analyzing bolted flange connections are the hand calculations based on simplified approaches and finite element analysis (FEA). While hand calculations lack achieving optimum weight as they tend to give over safe results, finite element analysis is computationally expensive because of the non-linear feature of the problem due to contact definitions between the mating parts.

In this study, a fast but very accurate design tool based on artificial neural network (ANN) is developed for the cylindrical bolted flange connection of a typical aircraft engine under combined axial and bending moment load. ANN uses the FEA database generated by taking permutations of the parametric design variables of the bolted flange connection. The selected parameters are the number of bolts, the bolt size, the flange thickness, the web thickness, the preload level of the bolt and the external combined loads of bending moment and axial force. The bolt reaction force and the average flange stress are taken as the output variables and the results of 12000 different finite element analyses are gathered to form a database for the training of the ANN. Results of the trained ANN are then compared with the finite element analysis results and it is shown that an excellent agreement exists between the ANN and the non-linear finite element analysis results within the training limits of the artificial neural network. We believe that the ANN established can be a very robust and accurate approximate model replacing the non-linear finite element solver in the optimization of the bolted flange connection of the aircraft engine to achieve weight reduction.
Theoretical Investigation Into Air Cooled Condenser Performance Optimization Through Parameterization for a 10 MW Power Plant
Authors: Bansal Mehul , Ghalamchi Behnam , Sopanen Jussi
Published: January 2018

Cooling is a significant part of any power generation cycle. An Air Cooled Condenser (ACC) is used to condense steam vapors from the steam turbine, lower heat rejection temperature and increase the power generation efficiency. An ACC works in a closed loop with the power turbine and its performance is directly linked to the power output of the power plant. In this paper, the heat transfer characteristics of ACCs are evaluated based on condenser design theory. For a given set of operating conditions and process parameters, it is possible to have multiple ACC designs. A case study has been presented on design optimization for real world steam turbine process parameters. The design optimization has been carried out through the parameterization of ACC parameters including, tube and fin diameters, their number, fin height, pitch, spacing and thickness. Each design parameter is affected by multiple ACC parameters and operating variables, which makes the optimization process challenging. Therefore, such optimization requires very systematic methodologies that are presented in the paper. Most commercial ACCs are designed through software simulations, that perform iterations based on the design criteria set by the user to arrive at an optimum design. The knowledge and results from the paper will help designers understand the contribution of critical ACC parameters affecting overall performance and input the best design criteria. This will help the industry to design thermally optimized ACCs.
Optimization of Process Parameters Applied to a Prototype Selective Laser Sintering System
Authors: Enzi Abass , Mynderse James A.
Published: January 2018

Selective laser sintering is an additive manufacturing technique that uses a high power laser to sinter or melt powder layer by layer to build 3D shapes. This paper focuses on creating a mathematical model of the crack width and surface roughness that occur during the selective laser sintering process. Response surface methodology is used to build and determine a mathematical model. Five variables at five levels are selected: forward step, side step, speed, platform temperature and layer depth. Based on response surface methodology, 32 experiments are used to determine the mathematical model of two selective laser sintering defects: crack width and surface roughness. Next, a genetic algorithm is used to determine the optimal solution to minimize crack width and surface roughness of the part. Results show that the five selected parameters have an effect on the target defects as confirmed by the resulting main effects plots, interaction plots, and contour plots. An optimal set of parameters is determined for future use.
Blowout Characteristics of Partially Premixed Flames of Prevaporized Blends of Biofuels and Petroleum Fuels
Authors: Maleta Tonci , Parthasarathy Ramkumar N. , Gollahalli Subramanya R.
Published: January 2018

The laminar partially premixed flames of prevaporized Jet-A, canola methyl ester (CME) and blend flames of Jet-A and CME were studied over a range of equivalence ratios of 0.6–0.8 with and without heated coflow. Measurements of blowout velocities and flame temperature profiles were made. The injector was designed to produce a uniform inner flow and had an inner diameter of 12.7 mm. The flames were laminar and blue in color (dominated by homogeneous gas-phase reactions). The temperature profiles in all the flames were similar, with a peak temperature of 1680 K. The blowout velocity increased with equivalence ratio for all the flames; the blowout velocity of pure CME flames was higher than that of pure Jet-A flames with no coflow present. The blowout velocity of the blend flames ranged around the values for the pure fuel flames. A Damkohler number (based on the velocity gradient at the jet boundary and chemical reaction time scale estimated from laminar flame velocity) of unity characterizes the blowout velocity. As the coflow velocity was increased, the blowout velocity was increased, and the differences between the values for the various flames became smaller.
Verification of a Manual Mesh Moving Finite Element Analysis Procedure for Modeling Ablation in Laminated Composite Materials
Authors: Wang Yeqing , Zhupanska Olesya I. , Pasiliao Crystal L.
Published: January 2018

One of the prevalent approaches to model ablation problems is to use the UMESHMOTION subroutine and the Arbitrary Lagrangian-Eulerian (ALE) adaptive remesh algorithm in ABAQUS (i.e., a commercial, general purpose Finite Element Analysis (FEA) software). However, the approach is not applicable for ablation problems when the material removal proceeds from one material domain to another, such as for ablations of laminated composite materials when the surface recedes from one laminate layer to another layer with different material orientations. In this paper, a novel procedure, based on manual mesh moving FEA with ABAQUS, is proposed to solve the ablation problems for laminated composite materials. The proposed procedure is verified by comparing the predictions of temperature and ablation histories of a two-dimensional isotropic panel (i.e., with single material domain) with those obtained using the traditional UMESHMOTION+ALE method. In addition, a case study is presented to demonstrate the successful application of the proposed procedure for the prediction of the thermal and ablation response of a laminated carbon fiber reinforced epoxy matrix (CFRP) composite panel subjected to a high-intensity and short-duration radiative heat flux.
Spatial Frequency Analysis for Improved Quality in Big Area Additive Manufacturing (BAAM)
Authors: MacDonald Eric , Burden Edward , Walker Jason , Kelly Jonathan , Conner Brett , Patterson Clark , Schmidt Austin , Bader Andrew
Published: January 2018

Process control in 3D printing (also known formally as Additive Manufacturing - AM) has largely been absent even in production systems. Simultaneously, computer vision has become more accessible with open source libraries (e.g. OpenCV, used successfully for traversing the state of California in an autonomous vehicle to win a DARPA Grand Challenge). 3D printing is particularly well suited to be enhanced by computer vision as fabrication is layer wise and predictable assuming correct operation. Big Area Additive Manufacturing (BAAM) — operating at significantly larger scales than traditional 3D printing — stands to benefit given the higher throughput of material (hundreds of pounds per hour) and the associated high costs of errant fabrication. Furthermore, minimum feature sizes in BAAM, such as individual layers, are sufficiently large to be analyzed with standard photography. With computer vision, sophisticated algorithms can be applied to identify problems early in the process that are not normally manifest until after process completion. Subtle and latent defects can be remediated before the onset of permanent damage or at a minimum the process can be aborted to avoid significant material loss. Fourier analysis can provide a useful perspective of the spatial periodicity of the layers of exposed surfaces during fabrication and this spectral information can inform the process of surface roughness, delamination, and deposition consistency in a data efficient manner. The large layer thickness of BAAM allow for Fourier analysis to be performed with standard photography. This paper explores the implementation and advantages of a low cost computer vision system that leverages OpenCV libraries operating on a Raspberry Pi Linux computer with simple yet high resolution photography — driven by the hypothesis that quality and yield of open source BAAM hardware can be dramatically enhanced.
Pressure Field of a Yawed Aspect Ratio 1 Circular Cylinder
Authors: Hiremath Nandeesh , Shukla Dhwanil , Pandey Anshuman , Gregory James W. , Komerath Narayanan
Published: January 2018

The aerodynamic loads and the flow around an Aspect Ratio 1 circular cylinder in the range of 300K to 400K Reynolds number, pose a surprisingly rich fundamental problem. This aspect ratio demonstrates features from the ‘coin’ limit as well as the high aspect ratio limit. Well-resolved measurements of all 6 components of aerodynamic loads became possible with the Continuous Rotation method. The genesis of the side loads, drag and yawing moment on a yawed aspect ratio 1 cylinder, is examined using 3 different methods. The first is direct pressure sensing on the flat side surface using pressure taps and individual sensors, done on similar setups at two different facilities. This is of course sparse but gives direct quantitative measures for validation. The second is pressure-sensitive paint (PSP), which provides a full distribution of pressure across the surface, with high spatial resolution that is limited only by the optics of the setup. The third is to extract the surface pressure using an algorithm that uses measured three-dimensional velocity data, along with the continuity and Navier-Stokes equations with a streamline-curvature model used to obtain the initial estimate. As possible, the measurements are compared with those computed from first principles using a Navier-Stokes solver. The streamline curvature method is validated against a numerical test case for an infinite cylinder, operated in the Foppl regime. It is then applied to the AR1 cylinder test case, and found to yield satisfactory comparison with interpolated surface plots from point measurements. The single-shot/transient PIV technique is applied to obtain the pressure map on the leeside and windward side of the yawed cylinder. The results are compared to point sensor data and PSP data. Comparisons of all these are shown, and linked to prior aerodynamic load measurements and computations. Agreement is good, with reasons for disagreement and uncertainty identified.
Convexity and Optimality Conditions for Constrained Least-Squares Fitting of Planes and Parallel Planes to Establish Datums
Authors: Shakarji Craig M. , Srinivasan Vijay
Published: January 2018

This paper addresses some important theoretical issues for constrained least-squares fitting of planes and parallel planes to a set of input points. In particular, it addresses the convexity of the objective function and the combinatorial characterizations of the optimality conditions. These problems arise in establishing planar datums and systems of planar datums in digital manufacturing. It is shown that even when the input points are in general position: (1) a primary planar datum can contact 1, 2, or 3 input points, (2) a secondary planar datum can contact 1 or 2 input points, and (3) two parallel planes can each contact 1, 2, or 3 input points, but there are some constraints to these combinatorial counts. In addition, it is shown that the objective functions are convex over the domains of interest. The optimality conditions and convexity of objective functions proved in this paper will enable one to verify whether a given solution is a feasible solution, and to design efficient algorithms to find the global optimum solution.
Anisotropy and Failure in Octahedral Lattice Structure Parts Fabricated Using the FDM Technology
Authors: Calise Gian J. , Saigal Anil
Published: January 2018

Mechanical metamaterials are man-made materials in which the mechanical properties are mainly defined by their structures instead of the properties of each component. Periodic cellular structures consisting of honeycomb, tetrahedral, 3D Kagome and pyramidal truss arrangement of webs or struts have recently attracted a lot of attention since they have a broad range of applications including structural components, energy absorption, heat exchangers, catalyst support, filters and biomaterials. In addition, lattice structures such as the octahedral are being investigated since they are structurally more efficient than foams of a similar density made from the same material, and the ease with which these structures can now be produced using 3D printing and additive manufacturing.

This research investigates the mechanical behavior and anisotropy in octahedral lattice structures of two different relative densities fabricated out of Acrylonitrile butadiene styrene (ABS) using Stratasys FDM 360mc and Dimension sst 1200es 3D printers. The machines were used to print octahedral lattice structured parts with struts 1.00 mm in diameter followed by parts with struts 2.6 mm in diameter and tested in compression in three mutually perpendicular directions. The compressive stress-strain behavior of the lattice structures observed is typical of cellular structures which include a region of nominally elastic response, yielding, and plastic strain hardening to a peak in strength, followed by a drop in flow stress. It was found that not only is the stiffness and strength of the as fabricated parts anisotropic but they, in addition to failure, are also a function of the relative density/strut diameter of the structure.
Effect of Micro-Grooving on the Stress Shielding of Titanium: Experimental and Numerical Investigations
Authors: Jamadagni Harsha G. , Karaman Hasan , Karpat Fatih , Williams Wendy , Dhanasekaran Lokesh , Khandaker M.
Published: January 2018

Micron sizes grooves can control the cell settlement on the implant surface or be used to direct tissue generation at the implant/bone interface. The effect of shape, size and the type of material of the microgrooves on the mechanical stimulus transfer from the implant to bone at physiological loading is not known yet. Therefore, this study evaluated both experimentally and numerically the effect of surface modification on a titanium implant to the load transfer characteristics from implant to bone for examining stress shielding parameters. This study measured the effect of micron grooves on titanium to the mechanical stability of titanium using a rabbit model. This study also developed a finite element model based on the in vivo test model to examine the stress shielding parameters. The results showed that the mean values of fracture strength were significantly higher for grooved titanium samples (1.32±0.45 MPa, n = 3) compared to control samples (without any groove) (0.22±0.16 MPa, n = 6) (P < 0.05). The load-displacement graph from the pull out tension tests was used to measure the frictional coefficient between Ti and bone from the FEA model. It was found from the FEA model that the average co-efficient of friction between titanium and bone was 0.50. Maximum equivalent stress along the interface of microgrooves on titanium was higher from groove area in compare to the non-groove area because of the change of the geometry along the groove. The microgrooves in the model have a significant effect on the stress transfer parameter between implant and adjoining bone. The unequal load sharing due to micro-grooving causes an increase in stiffness of the adjacent bone to the implant.
Improvement of Loading Capacity of Internal Spur Gear With Using Asymmetric Trochoid Profile
Authors: Yılmaz Tufan Gürkan , Doğan Oğuz , Yüce Celalettin , Karpat Fatih
Published: January 2018

Today, with numerous advantages such as reduced sliding velocity and wear, higher transmission ratio, higher running efficiency etc., internal spur gears are used in several industrial applications. An internal gear is generated by pinion cutters towards inside of gear blank opposite of external gear. In this study, bending stress of internal spur gear with the asymmetric trochoid profile is investigated. Asymmetry is ensured by using pinion cutter has different tip radius value on its right and left side. This situation is allowed to use larger tip radius on one side. The limit value of tip radius is defined with taking into account cutter addendum height and interference possibility for the given pinion gear parameters. On the other side, asymmetry on the involute region is also examined. Firstly, a mathematical equation of pinion cutter is derived then points of internal gear are obtained by using coordinate transformation, differential geometry and gearing theory in MATLAB. Points of internal gear are exported to CATIA to realize the 3D design. Case studies are conducted for determining the relation between tip radius and pressure angle on bending stress separately with ANSYS program. According to preliminary results, using asymmetric trochoid profile reduces approximately 16% bending stress of internal spur gear.
Intelligent Tire Based Pressure Monitoring Algorithm
Authors: Khaleghian Seyedmeysam , Taheri Saied
Published: January 2018

Intelligent tire is a relatively new technology that provides useful tire-road contact information by directly monitoring the interaction between the tire and the road. Different types of sensors are attached to the tire inner-liner for this purpose; the sensor data then will be used to estimate the tire-road contact parameters as well as to monitor the tire conditions.

In this study, a tri-axial accelerometer was used and a two-steps intelligent tire based pressure monitoring algorithm was developed in this study. First, the angular velocity of the wheel was estimated based on the parameters extracted from the acceleration components through a trained neural network. Then the estimated wheel angular velocity from the first step was used along with the acceleration components to estimate the power of radial acceleration. The estimated power was compared to the actual one and the tire pressure condition was judged to be “normal” or “low”. To train the neural networks, the experimental data collected using an instrumented vehicle was used. A VW Jetta 2003 was used for this purpose and instrumented with appropriate sensors; intelligent tires, steering wheel sensor to measure the steering angle, steering velocity and steering torque, encoders to measure the angular speed of the wheels and an Inertial Measurement Unit (IMU) to measure the vehicle linear and angular acceleration.

Another set of experimental data with different tire pressures and different vehicle velocity was then used to validate the algorithm; good agreements were observed between the estimated tire pressures and the actual ones.
Chemical Exergy of Fuels and Efficiency Analysis of Energy Utilizations
Authors: Shaoxiang Zhou
Published: January 2018

Many studies have investigated the chemical exergy of fuels. The results showed that it is equal to the negative standard free enthalpy change (SFEC) of the fuel combustion or the correction value. However, because the products of the combustion still have the chemical potentials of diffusion, the negative SFEC is not the whole of the chemical exergy of fuels. Because the accurate entropy of fuels cannot be obtained, the accuracy of the SFEC is doubtful and some corrections become necessary. But any correction risks misrepresenting the exergy balance of fuel-fired energy systems. In this paper, some important thermodynamic fundamental problems were studied, which showed that the chemical exergy of fuels should be equal to the negative standard enthalpy change. The formulas of total entropy generations and exergy efficiencies of energy utilizations were deduced, so that the exergy efficiency evaluation just needs heat balance data. The case studies were also given.
Mixing of Gases and Miscible Liquids in a T-Junction
Authors: Wei Wangshu , Haas Charles N. , Farouk Bakhtier
Published: January 2018

The transport processes in the mixing of either two gases or two miscible liquids in a T-junction are investigated numerically. Both laminar and turbulent flow fields are considered. The 3-D time-dependent flow fields are calculated for the T-junction (of two circular cross-section pipes that meet orthogonally at the junction). For turbulent flow regimes, the large eddy simulation (LES) technique is employed. In the 3-D mathematical model, the transport of species is described by the species conservation equations. The results obtained by the numerical simulations are verified with available experimental data in the literature for methane-air mixing in a T-junction. The effect of variation of the value of turbulent Schmidt number is investigated. Temporal concentration fluctuations are calculated and are compared to the spatial fluctuations. The mixing of two miscible liquids (water and peracetic acid-water mixture) are also investigated for the laminar and turbulent flow fields (using the LES technique). The mixing behavior of two gases and two miscible liquids in a T-junction are compared and contrasted for both laminar and turbulent flows.
Numerical Simulation of Water Droplet Freezing Process on Cold Surface
Authors: Yao Yina , Li Cong , Tao Zhenxiang , Yang Rui
Published: January 2018

It is significant to clearly understand the freezing process of water droplets on a cold substrate for the prevention of ice accretion. In this study, a three-dimensional numerical model including an extended phase change method was developed on OpenFOAM platform to simulate the freezing of static water droplets on cooled solid substrates. The predicted freezing process was compared with numerical results obtained by others. Good agreements were obtained and our numerical model results in faster convergence compared to the traditional phase change method. The effects of surface wettability on freezing time and freezing velocity were numerically investigated. The results show that the freezing time presents a positive relationship with contact angle due to the smaller contact area with higher contact angle, which agrees well with the theoretical analysis. Besides, the empirical relation between freezing time and contact angle were obtained.
One Dimensional Simulation of Droplet Ejection of Drop-on-Demand Inkjet
Authors: Jiang Huicong , Tan Hua
Published: January 2018

In this study, we present a 1D method to predict the droplet ejection of a drop-on-demand (DoD) inkjet which includes the drop breakup, coalescence, and the meniscus movement at nozzle orifice. A simplified 1D slender-jet analysis based on the lubrication approximation is used to study the drop breakup. In this model, the free-surface (liquid-air interface) is represented by a shape function so that the full Navier-Stokes (NS) equations can be linearized into a set of simple partial differential equations (PDEs) which are solved by method of lines (MOL). The shape-preserving piecewise cubic interpolation and third-order polynomial curve are employed to merge approaching droplets smoothly. The printhead is simplified into a circular tube, and a 2D axisymmetric unsteady Poiseuille flow model is adopted to acquire the relationship between the time-dependent driving pressure and velocity profile of the meniscus. Drop breakup and meniscus movement are coupled together by a threshold of meniscus extension to complete a full simulation of droplet ejection. These algorithms and simulations are carried out using MATLAB code. The result is compared with a high fidelity 2D simulation which was previously developed [10], and good agreement is found. This demonstrates that the proposed method enables rapid parametric analysis of DoD inkjet droplet ejection as a function of nozzle dimensions, driving pressure and fluid properties.
ByeLab: An Agricultural Mobile Robot Prototype for Proximal Sensing and Precision Farming
Authors: Vidoni Renato , Gallo Raimondo , Ristorto Gianluca , Carabin Giovanni , Mazzetto Fabrizio , Scalera Lorenzo , Gasparetto Alessandro
Published: January 2018

At today, available mechatronics technology allows exploiting smart and precise sensors as well as embedded and effective mechatronic systems for developing (semi-)autonomous robotic platforms able to both navigate in different outdoor environments and implementing Precision Farming techniques. In this work, the experimental outdoor assessment of the performance of a mobile robotic lab, the ByeLab — Bionic eYe Laboratory — is presented and discussed. The ByeLab, developed at the Faculty of Science and Technology of the Free University of Bolzano (I), has been conceived with the aim of creating a (semi-)autonomous robotic system able to sense and monitor the health status of orchards and vineyards. For assessing and measuring the shape and the volume of the canopy, LIDAR technology coupled with ad-hoc developed algorithms have been exploited. To validate the ByeLab different experimental tests have been carried out. In addition to the in-lab and structured environments experimental tests that allowed to tune the algorithms, in this work the assessment of its capabilities — in particular the sensoric system — has been made outdoor controlled environment tests.