bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the Involvement of Self-Directed Learning in Flipped Classrooms: A Unique URL-Based Search Method
Authors: Altuger-Genc Gonca , Genc Yegin , Tatoglu Akin
Published: January 2018

Ability to engage in lifelong learning requires the individuals to possess self-directed learning skills. ABET student outcome 3.i states that upon graduation a student should be able to demonstrate “a recognition of the need for, and an ability to engage in lifelong learning”. The challenge is in instilling these skills to students in traditional learning environments. In an effort to overcome this challenge, educators developed and implemented various approaches; one being the flipped classroom approach. One challenge when conducting research for self-directed learning environment in flipped classrooms is the challenge of finding relevant papers using keywords search. Terms, such as “flipped classroom” and “self-directed learning” may be included in relevant papers but not necessarily together. And searching these keywords separately will yield results that might have overlapping papers. This paper presents a unique URL-based literature search to identify the publications in the areas of self-directed learning in flipped classrooms by improving keyword-based literature search. It is followed by a title text analysis that will be used to identify the most common discussed topics in the database search results. In addition, an overview of how these methodologies can help the researchers identify the most relevant publications in the research area is presented. Challenges, observations and outcomes of both search methods are explained and analysis plots are presented.
Two-Phase Flow Behavior in Channels With Sudden Area Change Using Experimental and Computational Approach
Authors: Kotwal Ashish , Yang Che-Hao , Tang Clement
Published: January 2018

The current study shows computational and experimental analysis of multiphase flows (gas-liquid two-phase flow) in channels with sudden area change. Four test sections used for sudden contraction and expansion of area in experiments and computational analysis. These are 0.5–0.375, 0.5–0.315, 0.5–0.19, 0.5–0.14, inversely true for expansion channels. Liquid Flow rates ranging from 0.005 kg/s to 0.03 kg/s employed, while gas flow rates ranging from 0.00049 kg/s to 0.029 kg/s implemented. First, single-phase flow consists of only water, and second two-phase Nitrogen-Water mixture flow analyzed experimentally and computationally. For Single-phase flow, two mathematical models used for comparison: the two transport equations k-epsilon turbulence model (K-Epsilon), and the five transport equations Reynolds stress turbulence interaction model (RSM). A Eulerian-Eulerian multiphase approach and the RSM mathematical model developed for two-phase gas-liquid flows based on current experimental data. As area changes, the pressure drop observed, which is directly proportional to the Reynolds number. The computational analysis can show precise prediction and a good agreement with experimental data when area ratio and pressure differences are smaller for laminar and turbulent flows in circular geometries. During two-phase flows, the pressure drop generated shows reasonable dependence on void fraction parameter, regardless of numerical analysis and experimental analysis.
Demonstrating the Potential of a Novel Model to Improve Open-Loop Control of Electrostatic Comb-Drive Actuators in Electrolytes
Authors: Dibua Ohiremen , Mukundan Vikram , Pruitt Beth , Mani Ali , Iaccarino Gianluca
Published: January 2018

Electrostatic comb-drive actuators in electrolytes have many potential applications, including characterizing biological structures. Maximizing the utility of these devices for such applications requires a model capable of accurately predicting their behavior over both micron and submicron scales of displacement. Classic circuit models of these systems assume that the native oxide is a pure dielectric, and that the ion concentration of the bulk electrolyte is constant. We propose augmented models that separately address these assumptions, and analyze their ability to predict the displacement of the electrostatic actuators in electrolytic solutions. We find that the model which removes the assumption that the native oxide is a pure dielectric most accurately predicts comb-drive actuator behavior in electrolytes.
Simulating the Use of CO2 Concentration Inputs for Controlling Temperature in a Hydronic Radiant System
Authors: Sterman Michael , Baglione Melody
Published: January 2018

Incorporating predictive control into heating, ventilation and air conditioning (HVAC) systems has the potential to improve occupancy comfort and reduce energy use. This paper simulates the novel use of carbon dioxide (CO2) concentration inputs to augment temperature prediction and control. An artificial neural network (ANN) model and a least mean squares (LMS) filtering algorithm are used to simulate the temperature and control of a classroom in a high performance academic building with hydronic radiant heating and cooling panels. Numerical models are populated with variables that affect the heat energy entering, leaving, and being generated in a classroom. These variables include indoor and outdoor air temperature, radiant water and supply air temperatures, and classroom CO2 concentrations. The models are compared and then used to simulate the effect of a new control system that inputs CO2 measurements to account for the heat being generated by occupants of the controlled space. Simulation results suggest that augmenting HVAC control systems with CO2 measurements has the potential to improve temperature regulation by anticipating heating and cooling demand fluctuations in spaces with abrupt changes in occupancy.
Integrated Tolerancing and Motion Error Analysis of Suspension Assembly Considering Local Deformation in Suspension Shock Tower
Authors: Wang Hua , Li Mingshu , Zhao Liang
Published: January 2018

The suspension spring compression introduce local deformation in the suspension shock tower, and it brings the imprecision or uncertainty of the computer aided tolerancing (CAT) results of the suspension assembly. This work presents an integrated tolerancing and motion error analysis method of suspension assembly to consider the local deformation in the suspension shock tower. Tolerancing model of the suspension assembly is constructed in CAT software. FEA model provides the local deformation in the suspension shock tower introduced by the suspension spring compression under full loaded condition. The local deformation is represented with the modified probability distribution function (PDF) of the joining point between the suspension and the suspension shock tower. The modified PDFs of the joining points, together with the manufacturing deviations of the suspension parts are input to the constructed tolerancing model. The results are obtained that the final assembly variations of the suspension assembly under empty and full loaded conditions. Based on the tolerancing results, motion errors of the suspension from empty condition to full loaded condition are analyzed with the ADAMS model of the suspension. The results have shown that tolerancing and motion error analysis results considering the local deformation in suspension shock tower are more accurate than the initial normal distribution. The tolerancing and motion error analysis work presented in the paper will enhance the understanding of the suspension assembling, and help systematically improving the precision control efficiency in automobile industry.
Visco-Anisotropic Hyperelastic Finite Element Analysis of Knee Joint Considering Deformation Induced Anisotropy Evolution of Meniscus
Authors: Eguchi Tsuyoshi , Tomita Yoshihiro , Yamamoto Koji , Morita Yusuke , Nakamachi Eiji
Published: January 2018

Recently, the observation technology of micro structure has made great progress, and then collagen fiber orientation of meniscus can be measured accurately. This makes it possible to evaluate the stress in knee joint by considering the collagen fiber orientations at the micro scale. In this study, we developed visco-isotropic/anisotropic hyperelastic constitutive equations (Iso-VHE/Aniso-VHE) for menisci, which can reflect the initial collagen fiber orientations and their deformation induced rotations. Subsequently, we constructed a finite element (FE) model of normal human knee joint by using the magnetic resonance (MR) tomography images. The FE analysis with the proposed constitutive equations and FE model clarifies the reinforcement effect of collagen fibers on mechanical characteristics of knee joint.

Our computational prediction clarified that the stress concentration occurred on the contact parts of articular cartilages of femur and tibia, which met the tendency of the experimental results. Furthermore, the maximum compressive stresses evaluated by Aniso-VHE always showed a lower value as compared with Iso-VHE. This suggested that the anisotropy of meniscal collagen fibers relieved the stress concentration and lowered the maximum value. Therefore, our proposed FE analysis was proved to have a potential to reveal the functions of meniscus and knee joint.
Efficiency and Critical Velocity Analysis of Gravitational Separator Through CFD Simulation
Authors: Zhu Haiwen , Zhu Jianjun , Zhang Jiecheng , Zhang Hong-Quan
Published: January 2018

Oil and gas producing rates have increased rapidly with the development of shale oil and fracturing technology. Besides, advances in horizontal wells have increased the slugging issue, especially in complex geometry wells. Therefore, Artificial lift systems, especially rod-pumps and electrical submersible pumps, always suffer from associated gas and require an economical way to avoid problems like gas lock, gas pound, gas interference and slugging. Among all kinds of the downhole separator, and the gravitational separator are the most economical devices, which can handle severe slugging problems.

The rule of thumb liquid maximum downward velocity for the gravitational separator is 0.6 in/s [13, 14]. However, the criterion needs to be improved by considering pressure, temperature and fluid properties. This article first uses CFD simulations to validate the critical liquid velocity and then obtains pressure field, velocity profile, gas distribution and sensitivity factors under complicated field situations. The results could be used to develop an empirical or even a mechanistic efficiency prediction model in the future.

In this paper, 2-D simulation is first utilized to study the critical separation velocity and effective parameters. Comparing with Stokes’ law, the simulation shows density, and surface tension have a strong effect of critical separation velocity, while viscosity has lower influence. Then extended 2-D simulations are conducted on different inner tube to annulus connection geometry, which shows a strong effect on separation efficiency. Later on, 3-D CFD simulations are generated based on a newly designed separator by TUALP and an existing design from the Don-Nan separator. Simulations are used to validate 2-D conclusion and illustrate the improvement of the new design.
Hydrogen Generation From Waste Mg Based Materials Catalysed by Stainless Steel Net in Acetic Acid
Authors: Jen Tien-Chien , Hashe Vuyo , Chao Chung-Hsing
Published: January 2018

Low-grade Mg waste from post-consumer products and production waste cannot be recycled efficiently and economically. This work addresses this challenge by converting this waste into hydrogen. Mg waste is melt, loaded on one side of a stainless steel and solidified to form a galvanic Mg stainless steel couple. These couples are being used to generate hydrogen in 3.5% by weight CH3COOH solution at 15°C and 20°C respectively. The experimental results show that a mean accumulated H2 volume of 3.17 litres was produced when Mg stainless steel couple had a weight of 48.44 grams and water bath temperature of 15°C. One gram of low grade Mg yielded 2.91 Litres of H2. Another sample at 20°C with a weight of 52.73 grams showed a higher H2 volume yield of 3.21 litres per gram. This work can be expanded to a larger scale as the litres per gram volume indicates a lot more compared to what has been reported in literature.
Modeling and Experimentation of a Ribbed Caudal Fin for Aquatic Robots
Authors: Rios Oscar , Amini Ardavan , Murakami Hidenori
Published: January 2018

Presented in this study is a mathematical model and preliminary experimental results of a ribbed caudal fin to be used in an aquatic robot. The ribbed caudal fin is comprised of two thin beams separated by ribbed sectionals as it tapers towards the fin. By oscillating the ribbed caudal fin, the aquatic robot can achieve forward propulsion and maneuver around its environment. The fully enclosed system allows for the aquatic robot to have very little effect on marine life and fully blend into its respective environment. Because of these advantages, there are many applications including surveillance, sensing, and detection.

Because the caudal fin actuator has very thin side walls, Kirchhoff-Love’s large deformation beam theory is applicable for the large deformation of the fish-fin actuator. In the model, it is critical to accurately model the curvature of beams. To this end, C1 beam elements for thin beams are developed by specializing the shear-deformable beam elements, developed by the authors, based upon Reissner’s shear-deformable nonlinear beam model. Furthermore, preliminary experiments on the ribbed fin are presented to supplement the FE model.
Experimental Study of a Parabolic Trough Collector for Low Enthalpy Processes in the City of Barranquilla
Authors: Rodríguez Jainer S. , Villegas Duván C. , Vanegas Marley C. , Valencia Guillermo E.
Published: January 2018

Solar thermal energy is an alternative to provide heat for low-enthalpy processes at commercial and residential sectors in communities with energy sources scarcity. The present work is focused in the experimental performance analysis of a parabolic trough collector (PTC) designed and manufactured to minimize construction costs by setting the best parabolic profile and rim angle to improve thermal efficiency through enhancing light reflection in its parabolic surface, compound by conventional flat mirrors. The design considers an uncovered copper alloy receiver aligned with the focus of the reflective surface supported on a light metal structure. Sunlight collection area was defined at 1.2 m2 to allow installation of serial or parallel modular arrangements at reduced spaces like a building rooftop, the concentration ratio for this PTC is close to 33. This device was designed to use water as heat transfer fluid (HTF) and to be operated under environmental conditions of the city of Barranquilla, Efficiency curves were obtained based on experimental tests conducted with multiple HTF flow rate and varying reflecting surface slope for one PTC, obtaining a peak efficiency of 48 % and a without a tracking system. This device can be manufactured with a cost close to 80 USD/m2.
Effects of Inlet Arrangements on Liquid-Liquid Flow Patterns in Cross-Junction Square Microchannels
Authors: Qian Jin-Yuan , Wu Zan , Cao Zhen , Sunden Bengt
Published: January 2018

Due to the high surface area to volume ratios leading to intensified heat and mass transfer rates, microreactors have been subject of interest for some time. Liquid-liquid two-phase flow is a very common phenomenon in microchannels. During the scale-up using a numbering-up approach, rectangular and square microchannels are preferred to circular microchannels in terms of easier integration of the former with a less volume. Therefore, liquid-liquid two-phase flow in non-circular microchannels has been investigated recently. However, there are still gaps in the fundamental understanding of liquid-liquid two-phase flow, such as the effect of inlet junctions or arrangements on flow patterns in non-circular microchannels. The present work aims to study the effect of inlet arrangements on liquid-liquid two-phase flow dynamics and flow patterns of square glass microchannels. In this paper, oil is used as the dispersed phase and de-ionized water is used as the continuous phase. The special inlet arrangement in the cross-junction is compared to these common inlet arrangements of T-junction and cross-junction square microchannels. The effect of the inlet continuous phase velocity on the slug length is studied. Then, the slug lengths with the same inlet velocities of the three inlets and equal velocities of the two phases are carried out, respectively. Meanwhile, typical liquid-liquid flow pattern transitions are achieved at specific conditions. Finally, a special phenomenon without the droplet flow pattern is introduced, due to introduction of the novel inlet arrangement.
Study on Generation and Optimization Methodology of On-Machine Measurement Schemes for Multi-Axis CNC Machine Tool
Authors: Bohan Zhao , Feng Gao , Yan Li , Dongya Zhang , Wanli Zhang , Fei Zhou
Published: January 2018

Quality Control (QC) is one of the most important phases in the production process. In tradition, the workpiece must be inspected for dimension and shape errors in the QC lab or Coordinate Measuring Machine (CMM) after being machined, which is time-consuming and labor-intensive, especially for large scale parts. Thus the only practical way to do that is to migrate the critical primary inspection operations upstream from the QC lab or CMM to the production floor, and that’s what On-Machine Measurement (OMM) does. OMM technology can inspect the workpiece on its operating station by motion control and the position detection function of CNC machine tool, by which the measuring error caused by the misalignment between measuring datum and manufacturing datum can be avoided accurately. Therefore, it is a feasible way to achieve the real-time control of the manufacturing process and improve the manufacturing accuracy and efficiency. The servo axes of multi-axis CNC machine tool might be redundant for being used in OMM, which will result in that one measurement task could be done by different servo motion schemes. In addition, the map between the machine accuracy and measuring accuracy has not been found out previously. Thus, how to determine metering schemes to measure a workpiece with high accuracy and efficiency is one of the most important problems and also a hotspot for everybody. To solve this problem, a generation method of task-oriented OMM scheme is proposed. Utilizing multi-body system theory and transformation of homogeneous coordinates, a function relationship between the geometrical characteristic of workpiece as independent variables and motions of machine tool as dependent variables is established. All possible metering schemes are obtained by analyzing the solution of functional equation. Then the performance of measurement scheme can be evaluated by comparing the measuring errors of each scheme after building a mapping relationship between the machine tool volumetric errors and measuring errors. In the end, a case study was accomplished, and the correctness and efficiency of the methodology has been verified.
The Effect of Micro Molecular Parameters on the Actuation Performance of Electro Active Polymers
Authors: Sahu Raj Kumar , Yadu Shalabh , Singh Vaibhav , Raja Sagar , Patra Karali
Published: January 2018

This paper presents the results of theoretical study designed to measure the suitability of a dielectric elastomer as an actuator, from a group of acrylic and silicone elastomers. The micro molecular parameters of elastomers such as monomer type, monomer chain length and density were taken into consideration for analysis of actuation properties. Identification of monomer type of selected elastomers was done by using modified dielectric equations of polarization and stress induced due to applied electric field. The effect and the importance of electric field on the selected elastomers were also considered. To further understand the actuation potential of polymers, a comparison was done on the basis of their stress-electric field analysis. A conclusion was drawn on the basis of these comparisons and recommendations are given for an effective selection of polymers for use in actuator applications.
Adaptive Pre-Compensation of the Contouring Error for High-Precision Parametric Curved Contour Following
Authors: Ma Jian-Wei , Song De-Ning , Jia Zhen-Yuan , Zhang Ning , Hu Guo-Qing , Su Wei-Wei
Published: January 2018

Tasks of parametric curved contour following can be widely seen in computer-numerical-control (CNC) machining of parts with complex geometric features. Due to the existence of the contouring error in contour-following tasks, the machining precision of CNC machine tools will be seriously degraded. To reduce this error, methods such as cross-coupled control are extensively researched. However, these methods focus on compensation of the already happened contouring error, based on approximation of the error value according to the online measured actual motion positions. This paper presents an adaptive real-time pre-compensation approach, so as to control the contouring error before it really occurs. First, actual motion positions of the feed axes at the next sampling period are predicted, according to the z-domain model of each feed-drive system. To improve the adaptive capacity of the actual position prediction, the feed-drive models are identified online using the least-square method. After that, an accurate contouring-error calculation method, based on tangential-error backstepping using a moving frame, is proposed. Finally, the adaptive estimated contouring error at the next sampling period is compensated at the current period, thus beforehand improving the contour accuracy. Simulation and experimental tests are conducted to demonstrate the feasibility of the presented methods. From the testing results, it can be seen that the presented error-estimation method can precisely compute the contouring error, and the pre-compensation approach improves the contour-tracking accuracy dramatically, which is of great significance for improving the machining precision of the CNC machine tools.
Application of Order Statistics in the Evaluation of Flatness Error: Sampling Problem
Authors: Bartkowiak Tomasz , Staniek Roman
Published: January 2018

The main purpose of this initial paper is to demonstrate the application of order statistics in the estimation of form error from a CMM measurement. Nowadays, modern industry sets high standards for geometrical precision, surface texture and material properties. There are many parameters that can characterize mechanical part, out of which flatness error plays important in the assembly process and performance. Recently, due to the greater availability and price reduction, Coordinate Measurement Techniques have increased their popularity in the industry for on-line and off-line measurements as they allow automated measurements at relatively low uncertainty level. Data obtained from CMM measurements have to be processed and analyzed in order to evaluate component compliance with the required technical specification. The article presents an analysis of a minimal sample selection for the evaluation of flatness error by means of coordinate measurement. In the paper, a statistical approach was presented, assuming that, in the repetitive manufacturing process, the distribution of deviations between surface points and the reference plane is stable. Based on the known, statistical distribution, order statistics theorem was implemented to determine maximal and minimal point deviation statistics, as it played a dominant role in flatness error estimation. A brief analysis of normally distributed deviations was described in the paper. Moreover, the case study was presented for the set of the machined parts which were components of a machine tool mechanical structure. Empirical distributions were derived and minimal sample sizes were estimated for the given confidence levels using the proposed theorem. The estimation errors of flatness values for the derived sample sizes were analyzed and discussed in the paper.
Tutoring Experiences in PBL of Industrial Engineering and Management Program: Teachers vs Students
Authors: Alves Anabela C. , Moreira Francisco , Leão Celina P. , Teixeira Senhorinha
Published: January 2018

Teamwork tutors are one of the characteristic elements of the Project-Based Learning (PBL) methodology. PBL is considered to be an active learning methodology that involves the students in their own learning, by promoting the development of a large interdisciplinary project. The project runs typically over one full semester, or longer, and it is supported by a number of Project Supporting Courses (PSC) that teach and also applies its own contents aligned with project objectives. A set of activities, tasks and milestones are planned for each team so that the project objectives are accrued, with the aid of a tutor that follows the normal development and reports on its progress.

This paper discusses the role of the tutor from both sides: students’ and teachers’ tutors, and students in their first year of the Integrated Master in Industrial Engineering and Management program at the University of Minho. A total of thirteen tutors (four teachers and nine third year students) tutored six teams of students. Two on-line questionnaires were used to collect: 1) the perspectives of the tutored students with a total of 38 questions; 2) the perspectives of the tutors with a total of 22 questions. It was interesting to note that almost all students that answered to the questionnaire enjoyed having an older student tutoring them. The students’ tutors also enjoyed and they all had a good tutorship experience, being a special opportunity to help the first year colleagues.
Minimizing Weld Variation Effects Using Permutation Genetic Algorithms and Virtual Locator Trimming
Authors: Forslund Anders , Lorin Samuel , Lindkvist Lars , Wärmefjord Kristina , Söderberg Rikard
Published: January 2018

The mass production paradigm strives for uniformity, and for assembly operations to be identical for each individual product. To accommodate geometric variation between individual parts in such a process, tolerances are introduced into the design. However, for certain assembly operations this method can yield suboptimal quality. For instance, in welded assemblies, geometric variation in ingoing parts can significantly impair quality. When parts misalign in interfaces, excessive clamping force must be applied, resulting in additional residual stresses in the welded assemblies. This problem may not always be cost-effective to address simply by tightening tolerances. Therefore, under new paradigm of mass customization, the manufacturing approach can be adapted on an individual level. Since parts in welded assemblies are not easily disassembled and reused, interchangeability is not a relevant concern. This recognition means that each welded assembly can be adapted individually for the specific idiosyncrasies of ingoing parts.

This paper focuses on two specific mass customization techniques; permutation genetic algorithms to assemble nominally identical parts, and virtual locator trimming. Based on these techniques, a six-step method is proposed, aimed at minimizing thing effects of geometric variation. The six steps are nominal reference point optimization, permutation GA configuration optimization, virtual locator trimming, clamping, welding simulation, and fatigue life evaluation. A case study is presented which focuses on one specific product; the turbine rear structure of a commercial turbofan engine.

Using this simulation approach, the effects of using permutation genetic algorithms and virtual locator trimming to reduce variation are evaluated.

The results show that both methods significantly reduce seam variation. However, virtual locator trimming is far more effective in the test case presented, since it virtually eliminates seam variation. This can be attributed to the orthogonality in fixturing. Seam variation is linked to weldability, which in turn has significant impact on estimated fatigue life. These results underscore the potential of virtual trimming and genetic algorithms in manufacturing, as a means both to reduce cost and increase functional quality.
Micro-, Meso- and Macro-Scale Analysis of Composite Laminates by Unified Theory of Structures
Authors: Carrera E. , de Miguel A. G. , Pagani A.
Published: January 2018

In the present research, an advanced methodology for the multi-scale analysis of composite structures is proposed. It is based on the Carrera Unified Formulation (CUF), according to which any theory of structures, either 2D plate/shell or 1D beam, can be expressed as a degenerate case of Elasticity by using generalized expansions of the fundamental unknown fields. By using an extensive index notation, CUF allows the governing equations of the problem under consideration, and eventually the related finite element arrays, to be stated in terms of fundamental nuclei, which are invariant of the theory approximation order and the analysis scale. In this manner, micro-, meso-, and macro-scale models of composite structures can be formulated with ease and in a unified way, without the need of changing the model paradigms from one scale to the other. The capability of the proposed methodology based on CUF is assessed and the results demonstrate the validity of the approach, whose mathematical formalism is scale-independent, but allows for the simultaneous analysis of composites from global to very local scales in an accurate manner.
Application of Dynamic Bubble Departure Model for New, Low-GWP Refrigerants on Enhanced, Structured Surfaces
Authors: Shaligram Avinash , Saha Sandip Kumar
Published: January 2018

Structured surfaces consisting of sub-surface tunnels and openings in the form of pores or gaps are used to enhance boiling heat transfer resulting into compact heat exchangers. One of the applications of enhanced surface tubes is in flooded evaporators in water chillers. The fundamental mechanisms in nucleate boiling on structured surfaces are not still well understood, especially for new, low-GWP refrigerants. In this study, the focus is on bubble departure models. Most of the nucleate boiling models consider the static force model for calculating bubble diameter at the departure. However as per flow visualization studies in published literatures, the process of bubble growth and departure is dynamic and hence three more forces (in addition to buoyancy and surface tension) need to be accounted for while calculating the instantaneous bubble departure diameter. In this study, numerical results are presented for bubble departure diameter for four refrigerants, viz. R134a (the currently used, high GWP refrigerant) and its targeted low-GWP replacements, viz. R1234ze (E), R513A and R450A on enhanced, structured surfaces. Results from the dynamic force model show the bubble departure diameter in the range of 0.78 mm to 0.85 mm for all the four refrigerants. The unsteady growth force ranges from 4.8 × 10−6 N to 1.35 × 10−5 N while the surface tension force ranges from 2.49 × 10−6 N to 1.975 × 10−6 N. Similar results are provided for other forces as a function of wall superheat.
An Approach to Clean Particulates From Diesel Emissions: EDPS Baseline Prototype Testing Equipment and Methodology
Authors: Bardwell M. , Bari S. , Marian R.
Published: January 2018

Diesel exhaust particulate matter (PM) is deadly to humans, animals and plants so the future of diesel engine is uncertain. Alternative powered vehicles have major limitations and costly. Recent developments to limit PM emissions have significant disadvantages to the point where they cannot be considered to be reliable long term technical and economical solutions. Electrostatic filtration could be used together with existing filters or as a standalone system. The most popular method of decreasing PM emissions is by the use of ceramic diesel particulate filters which is not efficient at filtering ultrafine particulates. Electrostatic filtration is a promising approach which can capture ultrafine particulates which could be used in conjunction with ceramic DPFs, metallic flow through filters (FTF) or, ideally as a standalone system. Development of prototype electrostatic diesel particulate filtration systems (EDPS) requires reliable testing. Prototyping needs quick, repeatable and affordable results to validate theories and a solution had to be developed. This paper presents the development of the EDPS prototype testing procedures and equipment with preliminary test results. By repurposing proven test equipment for the use of exhaust sampling, a test rig and a repeatable procedure for testing prototype filters were developed with low initial and ongoing costs.
Dynamics Analysis of Planetary Gear Trains in a Wind Turbine Under Mean Wind Speed
Authors: Yang Jianming , Yang Ping
Published: January 2018

Targeting at planetary gear trains (PGTs) used in wind turbines, this paper investigates their vibration and dynamics under the aerodynamic torque of mean wind speed. Wind shear and tower shadow effects are considered in modeling the torque. A lumped parameter model is then developed to calculate the vibration and dynamics response of the PGT to the aerodynamic torque. In this model, the gear teeth and bearings are modeled as springs and the rotation of the carrier and the planet gears as well as the translation of the sun gear are taken into account. The time varying effect of the stiffness of gear mesh is incorporated into the model. Newmark algorithm is used to solve the vibration model established. In the last, the vibration response and dynamic meshing forces of the PGT are simulated and analyzed for rotors with 2 blades and 3 blades. The simulation result demonstrates that the aerodynamic torque is not a constant even under a constant wind speed. Instead, it changes with a frequency which equals the fundamental rotor frequency multiplied by the number of blades. The torque fluctuation causes corresponding vibration response and dynamic force fluctuation in the PGT.
Input Shaping for Flexible System With Nonlinear Spring and Damper
Authors: Chatlatanagulchai Withit , Moonmangmee Ittidej , Intarawirat Pisit
Published: January 2018

Input shaping suppresses residual vibration by destructive interference of the impulse responses. Because proper destructive interference requires superposition property of the linear system, traditional input shaper only applies to the linear flexible system. In this paper, the work and energy principle is used to derive input shaper for flexible system having nonlinear spring and damper. It was shown via simulation and experiment that this type of shaper performs well with nonlinear systems. Positive, robust, and negative input shapers are discussed.
Input Shaper Syntheses for Explicit Fractional Derivative Systems Using Nonlinear Optimization
Authors: Chatlatanagulchai Withit , Jatunitanon Poom , Nithi-uthai Sirichai
Published: January 2018

Fractional derivative system has gained its popularity in modeling and control because of its long memory property. Only recently, residual vibration suppression for the fractional derivative oscillatory system using input shaping has been studied. Input shaping suppresses residual vibration by using destructive interference of impulse responses. So far, only a few types of input shapers have been proposed for the fractional derivative oscillatory system, using only analytical, closed-form solutions. In this paper, input shaper syntheses for explicit fractional derivative systems using nonlinear optimization have been proposed. This work designs input shapers that have never been used with the fractional derivative system before, which include fixed-interval input shaper and specified-insensitivity input shaper, and extends the type that has already been used to a more general, improved input shaper.
Effect of Time and Acid Concentration on Metal Extraction From Galvanic Sludges
Authors: Vilarinho Cândida , Teixeira José , Araújo Jorge , Carvalho Joana
Published: January 2018

Galvanic sludge is a solid waste produced by the surface treatment industry, classified as hazardous because of their high concentration of heavy metals, which in its final destination is disposed in waste disposal facilities, with economic costs to the holders. Through hydrometallurgical processing, it is possible to extract valuable metals, with low costs involved, while the hazardous level of the residue is reduced.

In the present work, the heap leaching method was studied as a solution to the treatment of these residues, which in order to consist in a valuable option, processing and operation costs must be kept as low as possible. For the experimental testing, a closed loop lixiviation column for hydrometallurgical treatment of galvanic sludge with possibility of continuous flow of the leachate (and static process as well) was constructed, simulating the heap leaching process. The galvanic waste in study, delivered by a local surface treatment company, was both chemically and physically characterized, proving to be rich in valuable metals like Nickel, Chromium and Copper.

The waste material was characterized both for physical parameters (grain size) and chemical composition.

The lixiviation trials, with a maximum duration of 1 week, were conducted. The influence upon the extraction rate of metals such as Nickel, Chromium and Copper, of parameters such as the concentration of the leaching agent (sulfuric acid) and time were tested. In order to quantify the leachate circulation effect, a static trial was conducted as well. Extraction rates of 35.5 % of Nickel, 14% of Copper and 13.6 % of Chromium were obtained after 6 hours in a dynamic trial, with 100 g/L sulfuric acid solution concentration. The acid consumption rate was correlated with the metal extraction.

Finally, the results were compared with others obtained in previous galvanic sludge agitation lixiviation and laterites heap leaching works.
Review of Risk and Assessment of Safety for Powered Conveyor Systems
Authors: Kupkovits Robert , Kennedy Eugenia , Kornuta Jeffrey A.
Published: January 2018

Conveyor systems are common mechanical handling equipment used throughout many industries to transport materials in various directions — horizontally, vertically, at an angle or around curves — and at various heights including floor-mounted and overhead systems. There are many types of conveyors including both powered and non-powered. Each type of conveyor presents its own unique sets of hazards. Although conveyors reduce injuries associated with manual material handling tasks, they can present a different set of hazards to those installing, operating or maintaining them. These hazards are typically associated with the powered mechanical motion of belts, shafts, sprockets, chains and various other subcomponents. Many industry standards are currently in use for conveyors, such as ASME B20.1, Safety Standard for Conveyors and Related Equipment. These industry standards address safe practices in the design, construction, installation, operation and maintenance of conveyor equipment.

This paper will focus on identifying and defining the hazards associated with powered conveyor systems, reviewing workplace injury data for powered conveyors and comparing with data for nonpowered conveyors to better understand the trends, quantifying many of the risks associated with conveyors, and exploring and discussing the engineering and administrative controls currently available to address these hazards. A brief look at recent updates to some of the relevant standards will be presented to guide the discussion.
A Method to Determine Local Stress Fields in Microstructure Features Produced by Additive Manufacturing
Authors: Saunders Robert , Bagchi Amit , Achuthan Ajit
Published: January 2018

Metal power-based additive manufacturing (PAM) processes typically result in microstructures with a texture and columnar grains of different grain sizes, which affect the mechanical properties of the material. In this work, a method is developed to better represent the local granular stress fields within the microstructure. This is accomplished by converting a digital image segmentation from a synthetic microstructure into a shape-preserving finite element model with a microstructure-informed constitutive model that describes the mechanical behavior of solidified material produced by PAM. The new method to develop the finite element model allows the local stress intensification to be better captured in the vicinity of the grain boundary and helps with the prediction of defects and void formation in the material.
Compressive Properties of Post Cured Talc/Fiber Glass Filled Epoxy Composites
Authors: Lateju Omotinuola S. , Onitiri Modupe A. , Akinlabi Esther T.
Published: January 2018

The inclusion of fillers in conventional materials has been found to have significant effect on the various properties of the parent materials. In this present work, epoxy composite was fabricated using talc and fiber glass as fillers varying the particle size and loading while the composites were then post cured at temperatures of 50°C, 75°C, 100°C, 125°C and 150°C. The compressive behavior of the composites was then quantified by conducting compression tests in a controlled environment using specimens of simple geometry. It was discovered that compressive property increased with increase in post cure temperature and particle size and a decrease with increase in filler content.
Rate Dependent Reinforcement of Liquid Nanofoam on Thin-Walled Tubes
Authors: Li Mingzhe , He Bang , Barbat Saeed , Gu Sihao , Lu Weiyi
Published: January 2018

Thin-walled metal tubes have been widely used as energy absorbers to mitigate adverse effects of impact and protect structures and facilities. However, once the initial buckling stress of the tube is reached, the post-buckling plateau of the tube has a much reduced average stress which determines the energy absorption efficiency of the empty tube. As a result, the real energy absorption efficiency of the thin-walled tube is much lower than the theoretical limit which is proportional to the value of initial buckling stress. We hypothesize that by filling thin-walled tubes with the novel liquid nanofoam (LN), (i) the energy absorption efficiency of the hybrid structure can reach the theoretical limit, and (ii) the main working mechanism is the effect of solid-liquid interaction on tube buckling.

To test these hypotheses, we have characterized the energy absorption efficiency of LN filled steel tubes by using quasi-static compression tests and dynamic impacts. The quasi-static behavior of LN filled tubes is characterized by an Instron 5982 universal tester. Results show that the gravimetric and volumetric energy absorption efficiencies of LN filled steel tubes are 20% and 220% higher than the values of empty tubes, respectively. This is due to the changed buckling mode and the promoted post-buckling stress of the hybrid structure by the highly compressible LN. The dynamic behavior of LN filled tubes is characterized by a dynamic impact test (∼3 m/s) with a lab-customized drop tower apparatus. It is found that both the gravimetric and volumetric energy absorption efficiencies of LN filled tubes are further increased by 16%. The strain rate dependent behavior of LN filled tubes must be attributed to the solid-liquid interaction between the LN and the steel tube wall, which is further verified by comparing the mechanical behaviors of LN filled tubes with solid foams filled tubes.

Our experimental results have demonstrated that the energy absorption efficiency of thin-walled tubes are significantly improved by the LN filler especially at higher strain rates. This hybrid structure may have a potential for future use in the design of light-weight and small scale cellular structures for vehicle safety and crashworthiness.
Experimental Characterization for Helmet Pads
Authors: Zhang Timothy G. , Meredith Chris , Muller Allison , Moy Paul , Satapathy Sikhanda S.
Published: January 2018

In this study, quasi-static compression and dynamic impact experiments were conducted on helmet pads. Various layers of the foam pad: comfort, stiff and bilayer were tested to characterize their material response. In the compression tests, a piston compressed foam samples at constant velocity. The samples were tested under confined and unconfined conditions. In the dynamic impact experiments, the foam samples were impacted by a rigid projectile. Both the time histories of the force applied to the foam samples and the sample displacement were recorded to calculate the engineering strain and stress in the foam samples. The material stiffness in the impact tests was found to be several times that of the quasi-static tests.
Peridynamics Using Irregular Domain Discretization With MOOSE-Based Implementation
Authors: Chen Hailong , Hu Yile , Spencer Benjamin W.
Published: January 2018

In this paper, reformulation of classical bond-based peridynamic thermomechanical model for irregular domain decomposition and its MOOSE-based implicit formulation are presented. First, the irregular grid based peridynamic thermomechanical model is formulated and model parameters are derived. Following this, an implicit formulation for the solution of static or quasi-static problems is presented. Some aspects of the MOOSE-based implementation are given. After that, the formulation is verified against benchmark solutions for thermomechanic problems. Crack initiation and propagation in circular (2D) and cylindrical (3D) nuclear fuels at high temperature are studied using irregular grids.
Application of a Non-Interactive Constitutive Model for Life Prediction of 2.25Cr-1Mo Under Creep-Fatigue
Authors: Gordon Ali P. , Irmak Firat , Bouchenot Thomas , Felemban Bassem
Published: January 2018

Despite the significant progress in the development of modern alloys, low alloy steels continue to be the materials of choice for large structural components at elevated temperature for extended periods of time. The resistance of these alloys to deformation and damage under creep and/or fatigue at elevated temperature make them suitable for components expected to endure decades of service. The material 2.25Cr-1Mo is commonly applied in boilers, heat exchanger tubes, and throttle valve bodies in both turbomachinery and pressure-vessel/piping applications alike. It has an excellent balance of ductility, corrosion resistance, and creep strength under moderate temperatures (i.e., up to 650°C). In the present work, a life prediction approach is developed for situations where the material is subjected conditions where creep and fatigue are prevalent. Parameters for the approach are based on regression fits in comparison with a broad collection experimental data. The data are comprised of low cycle fatigue (LCF) and creep fatigue (CF) experiments. The form of the life prediction model follows the cumulative damage approach where dominant damage maps can be used to identify primary microstructural mechanism associated with failure. Life calculations are facilitated by the usage of a non-interacting creep-plasticity constitutive model capable of representing not only the temperature- and rate-dependence, but also the history-dependence of the material. For the inelastic response, both the Garofalo and Chaboche models for creep and plasticity are employed, respectively.