bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Louvered Plate-Fin Heat Exchangers Made via Additive Manufacturing
Authors: Bichnevicius Michael , Saltzman David , Lynch Stephen
Published: January 2019

Additive manufacturing (AM) can enable complex and novel designs that are otherwise infeasible with traditional metal manufacturing techniques. In low-volume production scenarios, particularly for specialized applications which can benefit from customized designs, traditional metal manufacturing techniques may be limited by costs associated with tooling. The ability to produce novel designs is particularly interesting in heat exchanger (HX) design where performance is often largely based on the achievable geometry. However, consequences of the AM process such as surface roughness, deviation from specified dimensions, and defects such as cracks and voids could also affect HX performance. These effects may vary between identically designed AM parts based on AM machine settings. The goal of this work is to gain a better understanding of the performance variations across several different implementations of the same heat exchanger design. More specifically, the objective of this work is to experimentally compare the thermal and hydraulic performances of a traditionally manufactured, stamped-aluminum aircraft oil cooler and three geometrically equivalent, additively manufactured counterparts. Compared to the traditionally manufactured heat exchanger, the AM HXs exhibited significantly higher air-side pressure loss and higher heat transfer despite having nominally similar geometries. Between AM HXs, there were slight differences in surface roughness characteristics based on optimal profilometry measurements. In addition, the thickness of the air-side fins varied as much as 15 percent between the AM HXs. The net effect, without the contribution of each cause clear, was higher air-side pressure loss and slightly higher heat transfer for the AM HX with thicker fins. This study indicates that functional heat exchangers built using AM vary in performance even when the same digital model is used to print them, and that AM HXs as a group perform considerably differently than their traditional counterparts. Thus, there is a need to account for anticipated surface roughness, geometric deviations, and potential defects when designing HXs. Proper consideration could result in improved thermal performance for future heat exchangers.
Development of Structural Neural Network Design Tool for Buckling Behaviour of Skin-Stringer Structures Under Combined Compression and Shear Loading
Authors: Okul Aydin , Gurses Ercan
Published: January 2019

Stiffened panels are commonly used in aircraft structures in order to resist high compression and shear forces with minimum total weight. Minimization of the weight is obtained by combining the optimum design parameters. The panel length, the stringer spacing, the skin thickness, the stringer section type and the stringer dimensions are some of the critical parameters which affect the global buckling allowable of the stiffened panel. The aim of this study is to develop a design tool and carry out a geometric optimization for panels having a large number of stringers. The panel length and the applied compression-shear loads are assumed to be given. In the preliminary part, a simplified panel with minimized number of stringers is found. This panel gives the same equivalent critical buckling load of panels having larger number of stringers. Additionally, the boundary conditions to be substituted for the outer stringer lines are studied. Then the effect of some critical design parameters on the buckling behavior is investigated. In the second phase, approximately six thousand finite element (FE) models are created and analyzed in ABAQUS FE program with the help of a script written in Phyton language. The script changes the parametric design variables and analyzes each skin-stringer model, and collect the buckling analysis results. These design variables and analysis results are grouped together in order to create an artificial neural network (ANN) in MATLAB NNTOOL toolbox. This process allows faster determination of buckling analysis results than the traditional FE analyses.
Limit Load Analysis of As-Fabricated Pipe Bends With Low Ovality Under In-Plane Closing Moment Loading and Internal Pressure
Authors: Sorour Sherif S. , Shazly Mostafa , Megahed Mohammad M.
Published: January 2019

Pipe bends are critical components in piping systems where their failure modes are quite different from straight pipes. The objective of the present work is to investigate the limit loads of pipe bends with actual As-fabricated shape obtained from pipe bending process as compared to bends with Ideal and Assumed imperfect shapes. The present work is conducted by using nonlinear finite element analysis and is performed in two steps. The first step is achieved by simulating rotary pipe bending process with ball mandrel to obtain the actual as-fabricated shape of the 90° pipe bend. The process simulation was verified against published experimental data. In the second step, the pipe bend is subjected to different combinations of simultaneous loads consisting of internal pressure and In-plane closing bending moment. Results are provided for limit load curves for pipe bends with as-fabricated geometries and bends with ideal shape and assumed geometrical imperfections.
Optimal Mechatronic Design of a Quadruped Robot With Compliant Legs
Authors: Arcos-Legarda Jaime , Hisham Khunsa , Anwar Sohel , Tovar Andres
Published: January 2019

The objective of this paper is to design a quadruped robot with compliant legs. Compliant legs are developed using flexible joints, which allow the robot to attenuate the effect of support-leg exchange. A model of the legs is generated in SimMechanics and optimized to minimize the maximum torque required by the actuators. The control of the robot is divided into two stages: (i) a gait central pattern generator, and (ii) a control system with feedback linearization. The gait pattern generator is developed based on optimal inverse kinematics with the use of Bezier polynomials. The resulting gait is used as a set-point in a closed-loop feedback control, which achieves a stable gait locomotion over rough, uncertain terrain. The uncertainty on the terrain causes unknown impacts in the robot. These impacts are absorbed by the compliance of the leg mechanisms. The proposed leg mechanisms are tested in a 3D-printed quadruped robot with fifteen degrees of freedom. Since, the robot is designed with eight actuators, the robot has seven degrees of under-actuation. The lack of actuators in this robot is overcame through the proposed gait pattern generator.
Exploration of Variable Conductance Effects During Input and Extraction of Heat From Phase Change Thermal Storage
Authors: Theroff Zachary M. , Helmns Dre , Carey Van P.
Published: January 2019

Previous efforts to model the effectiveness of heat input and extraction from a thermal storage unit have generally been based on the definition of a constant conductance of heat from the working fluid to the phase change storage material. In order to capture the effects of changing thermal resistance between the working fluid and melt front location, this paper presents a method using a resistor network analogy to account for thermal conductance as a function of melt fraction. This expression for thermal conductance is then implemented in an existing numerical framework. Results are validated by comparing calculations for a single unit cell using a quasi-steady Stefan problem approach, a finite difference scheme, and more general form solutions from literature. The variable approach is then compared with an average value for overall thermal conductivity, U, to characterize the performance of a thermal energy storage unit consisting of a series of these unit cells. Overall effectiveness in the thermal energy storage device is found to be within 0.6% agreement when comparing these methods, though local percent deviation can be as high as 113%. Depending on the needed accuracy and use case for such a numerical framework, suggestions are provided on whether an average value for U is sufficient for characterizing such a thermal energy storage device. Discussion is also provided on the flexibility of the computation schemes described by testing the sensitivity of the results via changes in dimension-less input parameters.
Using Multi-Channel Human-System Interaction for User-Centered Product Design
Authors: Sankowski Olga , Krause Dieter
Published: January 2019

User-centered product design (UCPD) and especially its methods and tools offer a lot of benefits to product development. By using specific data of the user group or by including them into the design process, systems with better functionality and usability arise. However, including the users in an optimum manner means to include them over the whole product development process, which is costly and often too time-consuming regarding the ever shorter product life cycles. An extensive application of UCPD methods is therefore usually not practical for industry.

In order to (1) support the user-centered development process in general and (2) support the selection of appropriate UCPD methods, a multi-channel human-system interaction framework is proposed. It is derived from existing human-computer and human-machine interaction models and further includes additional factors influencing the human-system interaction. However, the framework itself needs further and more detailed elaboration and discussion and currently lacks an allocation of UCPD methods.
Electrolyzer Exergy Analysis for an Environmental Control and Life Support System
Authors: Chow Raymond , Nelson George J. , Perry Jay L.
Published: January 2019

An exergy based analysis of the Environmental Control and Life Support System (ECLSS) aboard the International Space Station (ISS) is conducted to assess its overall performance. Exergy is chosen as a measure of performance because it accounts for both the first and second laws of thermodynamics. The exergy efficiency of a system is first defined as the total exergy destroyed by the system relative to the total exergy input to the system. To determine the ECLSS exergy efficiency, the system is divided into constituent subsystems which in turn are divided into assemblies and components. Based on this system decomposition, exergy balances are derived for each assembly or component. Exergy balances and supporting calculations are implemented in MATLAB® code. The major subsystems of the ECLSS considered in this analysis include the Atmosphere Revitalization Subsystem (ARS), Atmosphere Control and Supply Subsystem (ACS), Temperature and Humidity Control Subsystem (THC), Water Recovery and Management Subsystem (WRM), and Waste Management Subsystem (WM). This paper focuses on the ARS and its constituent assemblies and components. Exergy efficiency of the ARS and its constituent assemblies and components is first presented. The Oxygen Generation Assembly (OGA), an assembly within the ARS, is then highlighted because the exergy destruction by the OGA is a large magnitude contributor to the overall exergy destruction of the ECLSS. The OGA produces oxygen to meet the crew’s metabolic demand via water electrolysis in a proton exchange membrane (PEM) electrolyzer. The exergy destruction of the OGA’s PEM electrolyzer is a function of the amount of oxygen produced, which determines the necessary current density and voltage drop across the PEM electrolyzer. In addition, oxygen production in the PEM electrolyzer requires deviation from the Nernst potential, presenting trade-offs between the exergy efficiency and critical life support functions. The results of parametric studies of PEM electrolyzer performance are presented with an emphasis on the impacts of polarization and operational conditions on exergy efficiency.
Design and Control of a High Precision Laser-Cutting Machine
Authors: Van Bibber Mason , Bahr Behnam
Published: January 2019

Education in mechanical design and control theory is paramount to anyone interested in engineering and the “Maker” culture. Additionally, integration of concepts normally presented in discrete learning segments enhances technical and intuitive understanding of how systems work individually and together. This project aims to increase students’ understanding of engineering topics while equipping them with the necessary tools and information to recreate a high-precision laser-cutting machine at a minimal cost. These topics include electronic designs, mechanical assemblies, machine calibration, and control theory.

Although there is a wide range of laser-cutting machines currently available, most low-cost options are inaccurate and low-quality. Because such systems come preassembled and with little documentation, using them offers no educational value with respect to learning how the system functions. Since pre-assembled systems offer little hands-on learning potential related to their construction and design, the goal of this project is to develop a system that will offer this experience and enhance student understanding as they “Learn by Doing.” Students learning about the aforementioned topics will investigate them by constructing their own low-cost and reproducible laser-cutting machine. This system will enable students to study how to combine the ideas and theories learned throughout their engineering curriculum into a single design.
Integrating Collaborative Robots in Engineering and Engineering Technology Programs
Authors: Djuric Ana , Rickli Jeremy , Sefcovic John , Hutchison Donald , Goldin Michael M.
Published: January 2019

Collaborative robots (CoBots) are robots that can safely work alongside human workers. CoBots represent one form of advanced automation technology in manufacturing and are expected to become standard in production systems. They have the potential to transform manufacturing and assembly processes, however, there is a critical lack of U.S. trained CoBot technicians and engineers. The objective of this paper is to describe and introduce novel Collaborative Robotics course modules and their integration in Engineering and Engineering Technology programs at Wayne State University (WSU) and Oakland Community College (OCC). Modules cover three target areas: 1) Safety considerations for CoBots, 2) CoBot operations and programming, 3) Designing and evaluating CoBot systems. Modules cover fundamental knowledge of CoBots in advanced manufacturing systems and are developed based on input from CoBot manufacturers and experiments at the WSU’s Cobotics lab. Module components include CoBot fundamentals and hands-on laboratory exercises necessary to prepare a career-ready workforce, train industry professionals, and educate academicians on CoBot technologies for advanced manufacturing. Modules and components are developed such that the elements can be integrated into the current Robotics and Automated Systems Technology program at OCC and Engineering and Engineering Technology programs at WSU.
The Relationship Between Average Grain Profile Heights and Plastic Strains in Nickel Polycrystals Under Tensile Plastic Loading
Authors: Balusu Kranthi , Huang Haiying
Published: January 2019

We investigate the relationship between the average profile height and the average plastic strain of a grain in a polycrystalline material under plastic tensile strain using Crystal Plasticity Finite Element Method (CPFEM). The simulation consists of using an anisotropic grain embedded in an isotropic sample undergoing tensile plastic deformation. 150 different lattice orientations for the embedded anisotropic grain are used to represent all possible grain orientations. We found that plastic strain in the loading direction is not related to the surface profile height. However, the plastic strains in the direction normal to the surface and the transverse direction are linearly proportional to the average profile heights, irrespective of the grain orientation. The magnitude of the plastic strain in the direction normal to the surface decreases with increasing surface profile height. It is vice versa for plastic strains in the transverse direction. These results establish a possibility of determining a grain’s plastic strains from the profile height.
Design of Acoustic Metamaterials Using Gradient Based Optimization
Authors: Amirkulova Feruza A. , Norris Andrew N.
Published: January 2019

We derive formulas for the gradients of the total scattering cross section (TSCS) with respect to positions of a set of cylindrical scatterers. Providing the analytic form of gradients enhances modeling capability when combined with optimization algorithms and parallel computing. This results in reducing number of function calls and time needed to converge, and improving solution accuracy for large scale optimization problems especially at high frequencies and with a large number of scatterers. As application of the method we design acoustic metamaterial structure based on a gradient-based minimization of TSCS for a set of cylindrical obstacles by incrementally re-positioning them so that they eventually act as an effective cloaking device. The method is illustrated through examples for clusters of hard cylinders in water. Computations are performed on Matlab using parallel optimization algorithms and a multistart optimization solver, and supplying the gradient of TSCS.
Numerical Investigation on Simultaneous Effects of Surface Roughness and Variable Properties on Laminar Flow in Annular Tubes
Authors: Heydari Morteza , Bagheri AmirHossein , Sadat Hamid , Bostanci Huseyin , Nasrazadani Seifollah
Published: January 2019

A comprehensive study is conducted to evaluate the heat transfer characteristics of laminar nanofluid flow in an annular tube. Thermo-physical properties of the nanofluid is considered to be variable and for the inner and outer walls, there exists serrated surface roughness. The study focuses on the velocity distribution, friction factor and Nusselt number. All results are compared with those for the smooth channel and constant property nanofluid as well. The results show that the tube with serrated wall experiences greater maximum velocity. Moreover, decrease in velocity gradient and some other thermal characteristics result in decrease in average Poiseuille and Nusselt numbers for the rough tube with variable-property fluid.
Numerical Simulation on Aerodynamic Performance of Ram Air Turbine Based on Mixed Flow Field
Authors: Zhang Xiangbo , Ding Shuiting , Du Farong , Ji Fenzhu , Guo Shengrong
Published: January 2019

Ram air turbine (RAT) is an emergency power source to supply power in case of the main engine and auxiliary engine lost power. Which can extract energy from airflow through rotating turbine. So it is important to investigate turbine aerodynamic performances. According to some type of RAT, we established a numerical model based on Navier–Stokes equation in rotating frames of reference. Calculation domain is divided into three fluid domains. All three regions are linked in the form of interface. Aerodynamic performance of RAT is simulated with computational fluid dynamics (CFD) soft. The extracted power and rotor power coefficient are analyzed under different running conditions. Next, we also investigate RAT aerodynamic performance at different pitch angle and turbine speed. The pressure and velocity distribution on the blade surface are studied. Besides, the method of multiple rotation frame (MRF) is used to simulate mixed flow field of the RAT which pitch angle is adjustable. The simulation results show that: turbine output power and rotor power coefficient can meet the needs of aircraft by adjusting the pitch angle under various operation conditions. The optimal operating point could be obtained by calculating RAT aerodynamic performance. The distribution of blade surface pressure and velocity could provide an important reference for the optimization of turbine blade designing. MRF can be used to calculate turbine aerodynamic performance.
Transient Analysis of Air Flow in a Channel for Unconventional Radiator
Authors: Islam Wahidul , Khan Jobaidur Rahman
Published: January 2019

A number of cars are found to have an unconventional radiator. The radiator is placed at the back of the car instead of front, for which the radiator does not get the incoming airflow to cool the engine down and the engine gets overheated very easily. In order to deal with this problem, a channel has been mounted at the top of the vehicle to navigate incoming air flow and direct it through the radiator to cool down the engine. Three channels are tested computationally with three different lengths, which indicates the different way of studying this problem. Transient state analysis has been performed. Each length has its own characteristics. For example, a longer channel creates little circulation but more axial flow towards the radiator, while shorter channel creates smooth but less axial flow towards the radiator. All these cases in the steady state have the same domain and will have similar inlet variables like velocity, shape, size, and position.

A transient state simulation, most of the circulation were shown in the left-mid plane especially in longer channels. Transient state gives more uniform flow distribution. For longer channels in transient case, the flow is symmetric and smooth, while the flow is not found symmetric for short channel. The results were all made and developed in ANSYS for the final design where the data were simulated.
On Fine Tuning the SST K–ω Turbulence Model Closure Coefficients for Improved Prediction of Automotive External Flows
Authors: Zhang Chunhui , Uddin Mesbah , Selent Christian
Published: January 2019

Transient Scale Resolved Simulations, like the Detached Eddy Simulation, are currently seen to be the preferred modeling approach over the steady-state Reynolds Averaged Navier-Stokes (RANS) simulations for numerical investigations of external flow due to the former’s perceived capability of providing a more realistic flow field prediction. However, the latter approach is still a widely used methodology in road vehicle aerodynamic developments because of its faster turn-around time and cost-effectiveness. However, RANS models, like the SST k–ω, generally fail to produce well-correlated predictions. Studies reveal that good correlations with experiment cannot be achieved by simply refining the mesh when using the SST k–ω model. As such, this study explores the possibility of improving the prediction veracity by investigating the influence of a few selected model closure coefficients on the CFD prediction. This involves first identifying the effect of each individual model parameter on the prediction, and then formulating the best combination of the model closure coefficient values that yield the best correlation with the experiment. This procedure is applied to three different test objects: NACA 4412 airfoil at 12 degree angle of attack, the 25 degree slant angle Ahmed body, and a full-scale passenger road vehicle. Although some closure coefficients do not influence the CFD results much, the predictions are very sensitive to the choice of certain model constants, irrespective of the test object geometry. The study also shows that it is possible to formulate a combination of closure model coefficients that can produce very well correlated CFD predictions.
Experimental Analysis of Air Flow in a Channel for Unconventional Radiator
Authors: Salman Saad , Sharma Rishabh , Suri Kanishk , Khetani Zeshan Muhamed , Junaidy Muhammad Taha , Meza Jonatan , Khan Jobaidur Rahman
Published: January 2019

The automotive industry is one of the fastest growing industries worldwide with millions of vehicle productions and sales every year globally. Some of the vehicles have their engines in rear end, which means there is no incoming airflow from the front and the engine cannot cool down efficiently. The main aim of the research is to study the flow behavior for a duct that can detour the incoming air to the radiator for vehicles those have their engines located at the back. The duct collects the incoming air from the front of the vehicle and detour it to the engine located at the back. This helps in cooling down the engine in order to protect it from being overheated. The research is conducted to understand the detailed parameters to be accounted for while designing such a prototype. It is important to understand the essence of a cooling effect as the efficiency of the vehicle engine can only be maintained under a stable temperature. The research is important as it can be applied to diverse engineering problems. There are three cases for the experiment, each with different lengths. However, the inlet and outlet have identical dimensions for all three cases. There is a certain scale factor used to scale down the dimensions from a previously studied CAD model. These scaled down dimensions are then utilized to fabricate the prototype. Once the model has been constructed, a mesh is located at the outlet, which helps recording velocity magnitude and direction at each of the respective node of the mesh. One of the key elements of the research is to extensively understand the type of flow at different points of the duct and how they affect the efficiency of the design. For example, the curved parts where channels are installed along the length of the duct experience turbulent air flow. Hence, it is important to understand the influence of these flows on the efficiency of the design.
Digital Factory: Simulation Enhancing Production and Engineering Process
Authors: Thomas Angella , Guerra-Zubiaga David A. , Cohran John
Published: January 2019

Manufacturing system integration is an important industrial and research activity to explore Next Generation Automated Systems (NGAS). Manufacturing systems has been incorporating flexible, reconfigurable, smart and intelligent features. Advances in technology and trends such Industry 4.0 will revolutionize the manufacturing industry tremendously. Important subjects in this direction are Digital Twins, Internet of Things, and Collaborative Robots among others, are integral to continue the progression to create smart and reliable manufacturing processes. This paper aims to implement a method applying these concepts in a Flexible Manufacturing System (FMS) by providing a broad view of NGAS.
Study of Head Concussions on Female Soccer Players
Authors: Honarmandi Peyman , Palmisano Alessandra , Stashuk Iryna , Ladda Shawn
Published: January 2019

The goal of this research is to evaluate the extent of damage to the brain in regard to concussions when female soccer players head the ball to pass, defend, and score goals. It is reported that female soccer players have higher concussion rates than male players, which is why they will be the focus of this study. The anatomy of the female body seems to be structured in a way that increases the risk of concussions, but that has not been verified yet.

While many clinical studies document post-concussion results, our research evaluates the impact of the soccer ball during active play both computationally and experimentally. The force from the ball hitting the head and the resulting acceleration of the brain are analyzed. First, the head accelerations and corresponding HIC (Head Injury Criterion) values are obtained using computational programming. Then, a newly developed experimental framework is used to track the head acceleration using an accelerometer. The velocity and angle at which the ball makes contact with the head are measured using a projectile motion and time-lapse imaging technique. The results of heading the ball in different kick scenarios are compared with the threshold HIC values for concussions.
A Peak-Selection RBF Mesh Morphing Method for Subject-Specific Child Occupant Modeling
Authors: Yin Yunlei , Dong Wenxiang , Zhan Zhenfei , Li Junming
Published: January 2019

The mesh morphing method is widely applied in building subject-specific human finite element models. However, there are many problems yet to be resolved when applying the mesh morphing method in subject-specific modeling, such as calculation difficulties and low morphing accuracy. To solve these problems above, an efficient peak-selection RBF mesh morphing method is proposed in the paper. Firstly, by comparing different types of radial basis functions, an optimal kernel function is selected to improve morphing accuracy. Secondly, the landmarks are reduced by selecting multiple peak nodes from the object surfaces, so as to reduce iteration steps and improve the mesh generation efficiency. The proposed peak-selection Radial Basis Function (RBF) mesh morphing method is further demonstrated through a subject-specific child finite element modeling problem. This mesh morphing method has important significance for analyzing the occupant injury of different body features in motor vehicle crashes.
An Integrated Approach for Statistical Microscale Homogenization to Macroscopic Dynamic Fracture Analysis
Authors: Bahmani Bahador , Yang Ming , Nagarajan Anand , Clarke Philip L. , Soghrati Soheil , Abedi Reza
Published: January 2019

Maintaining material inhomogeneity and sample-to-sample variations is crucial in fracture analysis, particularly for quasibrittle materials. We use statistical volume elements (SVEs) to homogenize elastic and fracture properties of ZrB2-SiC, a two-phase composite often used for thermal coating. At the mesoscale, a 2D finite element mesh is generated from the microstructure using the Conforming to Interface Structured Adaptive Mesh Refinement (CISAMR), which is a non-iterative algorithm that tracks material interfaces and yields high-quality conforming meshes with adaptive operations. Analyzing the finite element results of the SVEs under three traction loadings, elastic and angle-dependent fracture strengths of SVEs are derived. The results demonstrate the statistical variation and the size effect behavior for elastic bulk modulus and fracture strengths. The homogenized fields are mapped to macroscopic material property fields that are used for fracture simulation of the reconstructed domain under a uniaxial tensile loading by the asynchronous Spacetime Discontinuous Galerkin (aSDG) method.
Variable Twist Blade Transformation to Improve Wind Turbine Performance
Authors: Khakpour Nejadkhaki Hamid , Hall John F.
Published: January 2019

A concept for an innovative wind turbine blade with an actively transformable twist distribution is presented. A simulation model demonstrates that adapting the blade twist distribution can increase the aerodynamic efficiency during partial-load operation. A blade concept consisting of a rigid spar that is surrounded by deformable modular shells is also proposed. The outer shells are assumed to be produced using additive manufacturing (AM) technology. Integrated features enabled by the AM process tune the stiffness, and thus the degree of flexibility for each surrounding segment. The unique local stiffness and the placement of actuators establishes a nonlinear twist angle distribution (TAD). An optimal design procedure is devised for setting the stiffness and actuator locations. It maximizes the aerodynamic efficiency for a discrete range of wind speed. The blade performance is quantified using data acquired from the National Renewable Energy Laboratory (NREL) Aerodyn software. A computer cluster is used to facilitate this process. It must consider the TAD for the range of wind speed that corresponds to the partial-load operation. The design procedure first establishes the TAD geometry based on the theoretical aerodynamic modeling. The TAD geometry is then passed to a mechanical design algorithm. At this point, the actuator positions are set, and the stiffness ratios of the adaptable shells are defined using the objective function. It minimizes the amount of deviation between the actual TAD and that found in the aerodynamic analysis. The free-shape TAD is determined in the final step. This is the shape of the blade when no actuation force is applied to the shells. This shape is then selected to minimize the amount of deflection needed to shape the TAD between its extreme positions. A case study demonstrates the ability of the blade and the proposed design process. The study indicates that a blade with five actuators can achieve the full range of TAD motion. The final solution shows that the adaptive TAD can increase the efficiency by 3.8 and 3.3%, respectively, at the cut-in and rated speeds.
Manufacturing Science Laboratory: Robotic Ultrasonic Welding
Authors: Yadav Prashant , Mauk Michael G. , Ruiz Carlos , Chiou Richard Y.
Published: January 2019

Robotic ultrasonic welding monitored in realtime with a force sensor and infrared thermal imaging camera is developed as an instructional project and laboratory component for undergraduate engineering education. The broad aim is to integrate robotics, plastic component manufacture, and thermal imaging with a unified theme. A secondary aim is to adapt ultrasonic welding for rapid prototyping as a tool for student design projects. Plastic parts for microsystems, such as lab-on-a-chip devices, made by laser cutting or 3d printing, are ultrasonically welded and tensile-stress tested and leaked checked.
A Biomechanical and Thermal Analysis for Bone Augmentation of the Proximal Femur
Authors: Farvardin Amirhossein , Bakhtiari Nejad Mahsan , Pozin Michael , Armand Mehran
Published: January 2019

In this study, we aim to create and validate a Finite Element (FE) model to estimate the bone temperature after cement injection and compare the simulation temperature results with experimental data in three key locations of the proximal femur. Simulation results suggest that the maximum temperature-rise measured at the bone surface is 10°C which occurs about 12 minutes after the injection. Temperature profiles measured during the experiment showed an agreement with those of the simulation with an average error of 1.73 °C Although additional experiments are required to further validate the model, results of this pilot study suggest that this model is a promising tool for bone augmentation planning to lower the risk of thermal necrosis.
Numerical and Experimental Characterization of Kerf Formation in Abrasive Waterjet Machining
Authors: Nyaboro Joseck Nyaporo , Ahmed Mahmoud A. , El-Hofy Hassan , El-Hofy Mohamed
Published: January 2019

Machining of hard-to-cut materials to a high degree of accuracy and surface quality is one of the most critical operations when fabricating different state-of-the-art engineered components. Abrasive waterjet machining (AWJM) is one of the non-conventional technologies, which is increasingly gaining a reputation for machining hard-to-cut materials. Despite many phenomenological investigations, the dynamic characteristics of the abrasive waterjet and physical interactions with the machined surface have not been thoroughly investigated in the context of understanding the machining process. The kerf geometry has been associated with several abrasive waterjet input parameters, but its characteristics have remained speculative among many researchers. In the present study, the governing equations of two-phase abrasive waterjet flow and the interaction with the material surface are developed and numerically simulated. With the help of precisely developed user-defined functions (UDF), the material removal process has been investigated. The dynamic jet characteristics and erosion rate are correlated to help characterize the kerf geometry. The proposed modelling approach is within the acceptable level of accuracy (< 5 %) when compared to experimental data. The results show that the jet dynamic characteristics and abrasive particle size significantly affect the kerf geometry and the material removal rate. The present findings not only provide a technical understanding of the AWJM process but also provide requisite guidelines in achieving high-precision machining of hard-to-cut materials.
Micro Combustor Development Using Hydrogen As Fuel
Authors: Shah Ronak , Kulshreshtha Digvijay , Chaudhari Nisarg
Published: January 2019

Swiss Roll Combustor of 1 W capacity for micro gas turbine engine is operated with premixed hydrogen air mixture at ultra-lean equivalence ratio. The reaction zone under consideration has volume of 60 mm3. The reactant passage and product passage are coiled around the reaction zone facilitating the recovery of heat loss, by preheating the reactants. The reactants are entered through an increasing cross-sectional area passage from 0.6mm × 5mm inlet to 1.5mm × 5mm outlet, thereby reducing the velocity levels in the reactant passage, facilitating stable combustor operation. The combustor performance parameters, temperature levels, pattern factor and emissions are measured is operated at ultra-lean equivalence ratio of 0.12 to lean equivalence ratio of 0.43, for premixed hydrogen air combustion. The results are compared at similar (not same) equivalence ratios for constant area reactant passage. The visual inspection shows stable flame front in the combustion zone for variable area passage and extended flame front in the constant area passage combustor. However, the combustor performance deteriorates drastically above equivalence ratio of 0.43, leading to hot spots generation on walls.
The Impact of the Gas Temperature and of the Relative Humidity on the Performance of Fans Operating in Drying Plants
Authors: Fritsche Manuel , Epple Philipp , Delgado Antonio
Published: January 2019

In order to investigate the impact of the gas temperature and its relative humidity on the performance of fans, the similarity laws for fans were extended and verified and numerical computations with the commercial CFD solver ANSYS CFX were performed. First the accuracy of the original fan laws was verified for different operating conditions. In a second step the influence of the temperature on the fan characteristics was investigated. Finally, to include the effect of the relative humidity multiphase simulations with air and water vapor were performed. Therefore, the relative humidity was analyzed for different gas temperatures. In such a way the full influence of the temperature and of the relative humidity on the performance characteristics of radial fans operating in drying plants was obtained. These numerical results have been analyzed in detail and compared with the results predicted by the presented extended similarity laws for turbomachines.
Prediction of Leak Rates Through Porous Materials Using Analytical and Numerical Approaches
Authors: Aweimer Ali Salah Omar , Bouzid Abdel-Hakim , Zhao Zijian
Published: January 2019

Characterizing the permeation performance of nano-porous material is an initial step towards predicting micro-flows and achieving acceptable designs in sealing and filtration applications. The present study deals with analytical, numerical, and experimental studies of gaseous leaks through soft packing materials.

The paper presents a new analytical model to accurately predict and correlate gaseous leak rates through nano-porous materials. The analytical prediction is done with a model of fluid flow through capillaries of an exponentially varying section. Based on Navier-Stokes equations with different flow regimes, the analytical model is used to predict gaseous flow rates through soft packing materials. In addition, for comparison, computational fluid dynamic modelling using CFX software is used to estimate the flow rate of compression packing ring materials assuming the fluid flow to follow Darcy’s law. Helium gas is used as a reference gas to characterize the porosity parameters. The analytical and CFX numerical leak predictions are compared to leak rates measured experimentally using different gas types (Helium, Nitrogen, Air, and Argon) at different pressures and gland stresses. The packing material is subjected to different compression stress levels in order to change its porosity.
Flexible Strain Sensor Using Additive Manufacturing and Conductive Liquid Metal: Design, Fabrication, and Characterization
Authors: Smith Austin , Bardaweel Hamzeh
Published: January 2019

In this work a flexible strain sensor is fabricated using Fused Deposition Modeling (FDM) 3D printing technique. The strain sensor is fabricated using commercially available flexible Thermoplastic Polyurethane (TPU) filaments and liquid metal Galinstan Ga 68.5% In 21% Sn 10%. The strain sensor consists of U-shape 2.34mm long and 0.2mm deep channels embedded inside a TPU 3D printed structure. The performance of the strain sensor is measured experimentally. Gauge Factor is estimated by measuring change in electric resistance when the sensor is subject to 13.2% – 38.6% strain. Upon straining and unstraining, results from characterization tests show high linearity in the range of 13.2% to 38.6% strain with very little hysteresis. However, changes due to permanent deformations are a limiting factor in the usefulness of these sensors because these changes limit the consistency of the device. FDM 3D printing shows promise as a method for fabricating flexible strain sensors. However, more investigation is needed to look at the effects of geometries and 3D printing process parameters on the yield elongation of the flexible filaments. Additionally, more investigation is needed to observe the effect of distorted dimensions of the 3D printed channels on the sensitivity of the strain sensor. It is anticipated that successful implementation of these commercially available filaments and FDM 3D printers will lead to reduction in cost and complexity of developing these flexible sensors.
Geometric calibration of very large microphone arrays in mismatched free field
Authors: Vanwynsberghe Charles , Challande Pascal , Ollivier François , Marchal Jacques , Marchiano Régis
Published: January 2019

Large microphone arrays are an efficient means for source localization thanks to a wide aperture and a great number of sensors. When such arrays are deployed in situ, accurate geometric calibration becomes essential to obtain the microphone positions. In free field, the classic procedures rely on measured Times of Arrival (TOA) or Time Differences of Arrival (TDOA) between the microphones and several controlled sources. However, free field model mismatches, such as reflectors, generate outliers which severely deteriorate the positioning accuracy. This paper introduces a unified framework for robust calibration using TOA or TDOA by exploiting an outlier-aware noise model. Thanks to the largeness of the array, the existing outliers are sparse and can be identified by a Lasso regression. From this, three iterative robust solvers are proposed: (i) for TOA by Robust Multi Dimensional Unfolding, a particular variation of Robust Multi Dimensional Scaling, (ii) for TDOA by data predenoising based on sparse and low-rank matrix decomposition, and (iii) for TDOA by jointly identifying the outliers and the geometry. The relevance of outlier-aware approaches is asserted by numerical and experimental tests. Compared with the baseline least-square approaches, the proposed robust solvers significantly improve the positioning accuracy in a free field mismatched by reflectors.
ClyJ Is a Novel Pneumococcal Chimeric Lysin with a Cysteine- and Histidine-Dependent Amidohydrolase/Peptidase Catalytic Domain
Authors: Yang Hang , Gong Yujing , Zhang Huaidong , Etobayeva Irina , Miernikiewicz Paulina , Luo Dehua , Li Xiaohong , Zhang Xiaoxu , Dąbrowska Krystyna , Nelson Daniel C. , He Jin , Wei Hongping
Published: January 2019

Streptococcus pneumoniae
is one of the leading pathogens that cause a variety of mucosal and invasive infections. With the increased emergence of multidrug-resistant
S. pneumoniae
, new antimicrobials with mechanisms of action different from conventional antibiotics are urgently needed.
Respiratory monitors to teach newborn facemask ventilation: a randomised trial
Authors: O’Currain Eoin , Thio Marta , Dawson Jennifer Anne , Donath Susan M , Davis Peter G
Published: January 2019

Objective

The International Liaison Committee on Resuscitation has found that there is a need for high-quality randomised trials of training interventions that improve the effectiveness of resuscitation skills. The objective of this study was to determine whether using a respiratory function monitor (RFM) during mask ventilation training with a manikin reduces facemask leak.

Design

Stratified, parallel-group, randomised controlled trial. Outcome assessors were blinded to group allocation.

Setting

Thirteen hospitals in Australia, including non-tertiary sites.

Participants

Consecutive sample of healthcare professionals attending a structured newborn resuscitation training course.

Interventions

An RFM providing real-time, objective, leak, flow and volume information was attached to the facemask during 1.5 hours of newborn ventilation and simulation training using a manikin. Participants were randomised to have the RFM display visible (intervention) or masked (control), using a computer-generated randomisation sequence.

Main outcome measures

The primary outcome was facemask leak measured after neonatal facemask ventilation training. Tidal volume was an important secondary outcome measure.

Results

Participants were recruited from May 2016 to November 2017. Of 402 eligible participants, two refused consent. Four hundred were randomised, 200 to each group, of whom 194 in each group underwent analysis. The median (IQR) facemask leak was 23% (8%–41%) in the RFM visible group compared with 35% (14%–67%) in the masked group, p<0.0001, difference (95% CI) in medians 12 (4 to 22).

Conclusions

The display of information from an RFM improved the effectiveness of newborn facemask ventilation training.

Trial registration number

ACTRN12616000542493, pre-results.
Efficacy of heavy eccentric calf training for treating mid-portion Achilles tendinopathy: a systematic review and meta-analysis
Authors: Murphy Myles Calder , Travers Mervyn J , Chivers Paola , Debenham James Robert , Docking Sean Iain , Rio Ebonie Kendra , Gibson William
Published: January 2019

Objective

To assess the effectiveness of heavy eccentric calf training (HECT) in comparison with natural history, traditional physiotherapy, sham interventions or other exercise interventions for improvements in pain and function in mid-portion Achilles tendinopathy.

Design

A systematic review and meta-analysis were conducted as per the PRISMA guidelines.

Data sources

PUBMED, CINAHL (Ovid) and CINAHL (EBSCO) were searched from inception until 24 September 2018.

Eligibility criteria

Randomised controlled trials comparing HECT to natural history, sham exercise, traditional physiotherapy and other exercise interventions were included. Primary outcome assessing pain and function was the Victorian Institute of Sports Assessment-Achilles.

Results

Seven studies met the inclusion criteria. This review suggests HECT may be superior to both natural history, mean difference (MD) (95% CI) of 20.6 (11.7 to 29.5, one study) and traditional physiotherapy, MD (95% CI) of 17.70 (3.75 to 31.66, two studies). Following removal of one study, at high risk of bias, due to pre-planned sensitivity analysis, this review suggests HECT may be inferior to other exercise interventions, MD (95% CI) of −5.65 (-10.51 to −0.79, three studies). However, this difference is unlikely to be clinically significant.

Conclusion

Current evidence suggests that HECT may be superior to natural history and traditional physiotherapy while HECT may be inferior to other exercise interventions. However, due to methodological limitations, small sample size and a lack of data we are unable to be confident in the results of the estimate of the effect, as the true effect is likely to be substantially different.

Systematic review registry

PROSPERO registration number: CRD4201804493

Protocol reference

This protocol has been published open access: Murphy M, Travers MJ, Gibson, W. Is heavy eccentric calf training superior to natural history, sham rehabilitation, traditional physiotherapy and other exercise interventions for pain and function in mid-portion Achilles tendinopathy?Systematic Reviews2018; 7: 58