bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Work and Power Analysis in the Joints of the Lower Extremity of Adults With Down Syndrome During Plane Walking
Authors: Taebi Amirtaha , Zago Matteo , Condoluci Claudia , Galli Manuela
Published: January 2018

Individuals with Down syndrome (DS) use a different motor gait strategy than healthy people. This study aims at analyzing plane walking differences between two groups of normally developed (ND) subjects and subjects with DS in terms of the generated mechanical power and work in the joints of the lower limb. Thirty-nine adults including two groups of 21 subjects with DS (age: 21.6 ± 7 years (mean ± SD)) and 18 ND subjects (age: 25.1 ± 2.4 years) participated in this study. Gait data and ground reaction forces were acquired using a quantitative movement analysis system composed of an optoelectronic motion analyzer (Elite2002, BTS) with eight infrared cameras, and two force platforms mounted in the middle of walkway. Mechanical power and work exchanges were computed during the stance phase by dedicated software, and then compared between the two groups (significance level: p-value = 0.05). Results showed that the mechanical power at the ankle joint was significantly larger in ND subjects compared to subjects with DS (0.084 ± 0.015 vs 0.027 ± 0.010 W/kg). The mechanical work of the ankle joint and the knee joint was significantly lower in ND compared to DS (0.015 ± 0.013 vs 0.028 ± 0.008 kJ/kg.m, and 0.066 ± 0.031 vs 0.109 ± 0.023 kJ/kg.m, respectively). For both groups, the mechanical work done by knee was less than that performed at the ankle and hip level, which might indicate that the knee muscles mainly absorb the energy, rather than generate it. Our results suggest that the subjects with DS walk with a different motor strategy than normal subjects in terms of mechanical power and work in the joints of the lower extremity. Further investigations are warranted to study the relation between these parameters and gait strategy in subjects with DS, which can lead to better rehabilitative strategies.
Heat Transfer Optimization in Laminar Flow of Non-Linear Viscoelastic Fluids in Asymmetric Straight Ducts With Inclusions
Authors: Letelier Mario F. , Siginer Dennis A. , Arriagada Gabriel , González Amaru
Published: January 2018

This paper presents the preliminary findings of an optimization study of transversal flow strength in tube cross-sections with arbitrary external contours and an internal inclusion. The eccentric tube contours are generated through a one-to-one mapping of a base circular cross-section. The working fluid obeys the non-linear modified Phan-Thien-Tanner (MPTT) constitutive model. The computation of the total transversal flow rate leads to the determination of effective cross-sections for heat transfer enhancement.
Biosensor Based on Layer by Layer Deposited Phosphorene Nanoparticles for Liver Cancer Detection
Authors: Kim Jungyoon , Sando Shota , Cui Tianhong
Published: January 2018

Properties of phosphorene are intensively researched by many research groups since it was discovered in 2014. This new 2D material has a direct band-gap, depending on the number of layers (0.3 eV for bulk to 2.0 eV for monolayer) similar to MoS2. In this paper, we report layer-by-layer (LbL) deposition method to deposit a few layers of phosphorene film on the substrate, and successfully fabricate phosphorene field effect transistor (FET) with LbL black phosphorus (BP) film. By using the FET characteristics of the device, we fabricate biosensors with Poly-L-lysine (PLL) linker molecules and Alpha-fetoprotein (AFP) antibody to detect different concentration of AFP antigen (0.1 ppb to 1 ppm). The results indicate that BP can be a promising material for biosensing applications.
Buckling Analysis of a Functionally Graded Implant Model for Treatment of Bone Fractures: A Numerical Study
Authors: Taebi Amirtaha , Khalili Fardin , Taebi Amirtaher
Published: January 2018

In orthopedics, the current internal fixations often use screws or intramedullary rods that obstruct bone material. In this paper, an internal implant was modelled as a hollow cylindrical sector made of a functionally graded material (FGM), which will hold bone in place with less obstruction of bone surface. Functionally graded implant was considered as an inhomogeneous composite structure, with continuously compositional variation from a ceramic at the outer diameter to a metal at the inner diameter. The buckling behavior of the implant was numerically analyzed using a finite element analysis software (ANSYS), and the structural stability of the implant was assessed. The buckling critical loads were calculated for different fixation lengths, cross sectional areas, and different sector angles. These critical loads were then compared with the critical loads of an FGM hollow cylinder with the same cross sectional area. Results showed that the critical load of the hollow cylindrical sector was ∼ 63%, ∼ 70%, and ∼ 73% of the hollow cylinder for different fixation lengths, cross sectional areas, and sector angles, respectively. Further investigations are warranted to study the relation between the composition profile and the implant stability, which can lead to batter internal fixation solutions.
The Effect of Ash Cleaning Cycles on Thermal Characteristics of Moxibustion Therapy
Authors: Sun Chao , Li Ying , Kuang Jiujie , Ji Changchun , Wu Jiangtao
Published: January 2018

Objective: In clinical treatment, ash cleaning is an effective way to enhance the thermal efficiency of moxibustion. Understanding the thermal characteristics of moxibustion therapy with ash cleaning is necessary to improve its clinical efficiency. Method: Temperature distributions of burning moxa sticks were measured with an infrared camera. The moxa burning duration was set at 20min with different ash cleaning cycles (3min, 4min, 5min and no ash cleaning). A moxa stick burning model with ash cleaning was built to analyze the detailed burning discipline and compared with experimental results. In addition, temperature distributions of in-vitro tissue during moxibustion with different ash cleaning cycles were obtained using thermocouples and infrared camera. Results: Ash cleaning has effectively extended the high-temperature areas of moxa sticks and accelerated the burning velocity. Shorter ash cleaning cycle led to higher average temperature of moxa sticks. The simulated results agreed well with experimental data, which indicates that the moxa stick burning model with ash cleaning is reliable to reveal the burning discipline of moxa sticks. For in-vitro tissue, ash cleaning induced obvious temperature rise at tissue surface and slight rise in deep tissue. Compared with 3 min and 5 min, the ash cleaning cycle of 4 min is the recommended value.
New Approach for Architecture Design of High Variable Vehicle Portfolios
Authors: Felgenhauer Matthias , Stocker Johannes , Lienkamp Markus
Published: January 2018

Following the trends of mass customization, globalization and environmental protection, new customer and legal requirements must be fulfilled in vehicle product development. The drivers named above often result in an increasingly complex product portfolio regarding the variance of components and mounting positions. Passenger cars and commercial vehicles are most affected by this, offering individualization in large quantity.

As a result, the Vehicle Concept Development Process (VCDP) is becoming inscrutable and inefficient, since common methods are not entirely adapted to the huge variety of requirements and therefore components. This paper introduces a new approach to the Vehicle Architecture Design phase of passenger cars and commercial vehicles. The current package process can be divided in three phases. Within the phase of the Vehicle Dimension Design (VDD), exterior dimensions and passengers’ positions are defined. During the Vehicle Architecture Design (VAD), the drivetrain- and vehicle architecture is developed. Followed by the Vehicle Package Design (VPD), all components, including hoses and wires, are integrated into the vehicle.

In a first step, the proposed approach integrates a combination of requirement and dependency management into the architecture design. It is necessary to get a transparent overview of the requirements and their dependencies at an early stage of concept development. To manage the variance of components and their mounting positions, all components to be considered during VAD must be distinguished and prioritized by their impact on the concept and the variance within the second step of the method. Their significance is assessed according to suitable criteria. Based on this selection, only a certain number of components is considered during the architecture design. Components not matching the criteria are shifted for integration during the package design. During the third step, creation of manageable architecture alternatives is assisted by the reduced number of components. Afterwards the concept alternatives are evaluated based on the level of similarities and standardization. Consequently, the transparency and efficiency is increased by the three steps of the new method for VAD.
Optimized Modelling and Fabrication of a Parabolic Leaf Spring With Finite Element Analysis
Authors: Ishtiaque Md Tahsin , Joo Sung-Hwan
Published: January 2018

A leaf spring is a simple form of spring commonly used for suspension system of vehicles which is originally called laminated or carriage spring. They perform isolation task in transferring vibration due to road irregularities to driver’s body. To improve the suspension system, many modifications have taken place overtime but recent innovations imply parabolic leaf spring and application of composite materials for these springs. The conventional flat profile of the leaf spring has been transformed into parabolic leaf spring which facilitates lighter, cheaper, better fatigue life and isolating more noise. This project basically includes designing a leaf spring with a conventional flat profile design following the standard dimension (SAE Manual) with acceptable tolerance and regard it as the base model for the project. To obtain the deformation, stress and fatigue life of the base model; a Computer Aided Simulation has been carried out in ANSYS Workbench considering the Structural Steel as the base material. Afterwards, the conventional flat profile design has been changed to parabolic shape consisting 1 Master leaf and 3 graduated leaves. In this case, initially the structural steel has been selected as the base material and later on SAE 5160 steel has been implemented to carry out the simulation. As only spring steel is the material widely used for parabolic leaf spring and many research has been carried out with spring steel, therefore different materials with combination of different spring design has been carried out in this project to get a better life cycle compared to the widely used one. After first modification, number of leaves has been increased to 5 but analysis has been carried out with the same two materials considered for initial simulation. Due to time constraint, the final optimized design has been selected among the analysis finished with the combination of leaves and materials which incorporate the better fatigue life, reduced deformation, reduced weight of the spring and increased factor of safety and later on following the final design (analyzed from CAE results) the parabolic leaf spring has been built with the assistance of a spring shop.
Heat Transfer in Three-Dimensional Single-Span Greenhouses Containing a Roof Ventilator
Authors: Kruger Sunita , Pretorius Leon
Published: January 2018

Greenhouses are used worldwide to grow various types of plants in climates and seasons not usually adequately suited for optimum growth. The microclimate inside greenhouses is of major importance as it directly affects the quantity and quality of crop production. Ventilation is a vital mechanism for maintaining an acceptable indoor climate for optimum plant production. A three-dimensional CFD model of a single span greenhouse with roof ventilators is presented. CFD results from a two-dimensional version of the model are compared with appropriate previous experimental results. The role of the Standard versus Low-Reynolds number k-epsilon turbulence model is emphasized. The addition of a ventilator to the roof of a single-span greenhouse was found to have an influence on the heat transfer inside the cavity. Various configurations of three-dimensional CFD models of the greenhouse with different ventilator opening sizes for zero and 45 degrees roof angle were investigated. Additional Nusselt-Rayleigh number relationships for specific Rayleigh number ranges were deduced, and can be useful for a greenhouse designer.
Analysis of Hybrid Programming Simulation Based on the Variable Stiffness Ring With Expanding Loop SMA Actuator
Authors: Wang Lei , Deng Zong-quan , Wang Hao-di , Yue Hong-hao
Published: January 2018

In the development of space craft design index, the requirements of hypersonic space craft control accuracy has been increasingly rigorous. Thin-walled structure is often employed in hypersonic craft to reduce the weight of the load and to save the room. During the flight of the craft, temperature field is produced along the surface and the dynamic properties of the craft structure are obviously changed. The decreasing elastic modulus of the structure material and the appearance of thermal stress lead to the decrease of integral rigidity and stability of the structure, then the thermal flutter appears and control difficulties increase. Shape Memory Alloy (SMA) has the advantages of the considerable driving force in the compact volume and the simple driving method. By the combination of actuator structure design and stiffness control, the smart structure is able to make active control to the thermal stiffness variation.

In this paper, the apex high-temperature area is equivalent to a ring structure. Finite difference method is employed firstly to transform the governing partial differential equation into discrete finite difference equations. Then the elastic modulus change, thermal stress and tension along the circumference are considered comprehensively to propose the calculation formulas of equivalent young’s modulus. The discrete dynamic matrix model is obtained containing the control terms of SMA. To solve the big-matrix calculation and multiple iterated large data problem, hybrid program is developed with C++ and MATLAB. Finite element software is employed to make optimization analysis to design an expanding loop actuator containing SMA as driving source, variable thickness loops of spring steel as expanding units, and universal-ball pre-loading units. On the basis of that, the thermal stiffness variation active control system with smart structure is developed based on expanding loop SMA actuator. After the analysis of examples, the variation law of the needed SMA driving force is obtained. The distribution position and quantity of the driving source is optimized. This research provides reference for the Theoretical Analysis and Simulation of structure stiffness active control and adaptive control of the aircraft employing smart material. The research results have guiding significance for the smart structure design of hypersonic aircraft in the future.
A Component-Wise Approach for the Failure of Complex Aeronautical Structures
Authors: Viglietti Andrea , Zappino Enrico , Carrera Erasmo
Published: January 2018

Using advanced beam models based on the Carrera Unified Formulation, this paper presents an analysis of a damaged tapered aircraft structure. Results obtained from static and free vibration analyses are presented to evaluate the evolution of the stress and the modal behaviour in a multi-component damaged structure. This 1-D model is able to modify the material proprieties, then the stiffness, at the local level. In this way, many types of local and global damage can be introduced into the structure. The results show the capability of the present model to obtain with a low computational cost, displacements, stresses and vibration characteristics of damaged structures making him a good candidate for design and maintenance tools.
Refuse Derived Fuel (RDF) Gasification Using Different Gasifying Agents
Authors: Ribeiro A. , Vilarinho C. , Araújo J. , Carvalho J.
Published: January 2018

Wastes represent nowadays, one of the major concerns for modern societies and for the environment, either by the wastage of raw materials and also by the existence of poor management systems that can originate and contaminate the ground water and air, and therefore, change the environment irreversibly. Waste management policies enhance the basic principles of prevention, which are the reduction in origin, followed by its recovery through recycling or energy recovery, in order to reduce the environmental and health impacts of wastes. Refuse Derived Fuel (RDF) is a solid fuel made after basic processing steps or techniques that increase the calorific value of municipal solid waste (MSW), commercial or industrial waste materials. Therefore, energy production from RDF can provide economic and environmental benefits, as reduces the amount of wastes sent to landfill and allows the energy recovery from a renewable source.

In this work, it was studied the gasification of RDF collected in a Portuguese company, using steam and air as gasifying agents. This study intended to evaluate the effect of temperature and different molar ratios of both agents in gas production, gas composition and mass conversion of RDF.

Physical and chemical composition of RDF was determined according to EN 15359:2011. Results showed that RDF has high quality for thermal valorization being registered high values of Low Heating Value (LHV) (24330 kJ/kg), carbon content (56.2%) and volatile matter content (77.2%). Experiments of RDF gasification were performed in a laboratory scale fixed bed gasifier, under different conditions. The effect of reaction temperature was studied at 750°C and 850°C. Gasification experiments with steam were executed at S/B feeding molar ratios ranging from 0.5 to 1.5 and the ones performed with air ranging from ER 0.2 to 0.6. Results showed that, for the same operational conditions, the rise of gasification temperature improved gas production ratio (Nm3/kg RDF), gas LHV and mass conversion. Results also proved that steam gasification achieved higher LHV values compared with gasification using air in optimal conditions, 9.4 and 9.8 MJ/m3, respectively. The gasification of RDF using steam at S/B ratio of 1.0 enables the production of syngas with 51% of hydrogen (H2), 32% of carbon dioxide (CO2), 11% of carbon monoxide (CO) and 6% of methane (CH4) (in N2 free basis). The increasing of steam to RDF molar ratio, increased the contents of H2 and CO2, while the content of CO, CH4 and heating value decreased. Regarding to gas production ratio the utilization of air, especially at ER of 0.6, induced the formation of 1.5 m3 gas/kg RDF. Instead, steam gasification only allowed the production of 0.5 m3 gas/kg RDF. Mass conversion and carbon conversion achieved almost 100% in air gasification at highest molar ratio.
Micromechanical Progressive Failure Analysis of Fiber-Reinforced Composite Using Refined Beam Models
Authors: Kaleel Ibrahim , Petrolo Marco , Carrera Erasmo , Waas Anthony M.
Published: January 2018

An efficient and novel micromechanical computational platform for progressive failure analysis of fiber reinforced composites is presented. The numerical framework is based on a class of refined beam models called Carrera Unified Formulation (CUF), a generalized hierarchical formulation which yields a refined structural theory via variable kinematic description. The crack band theory is implemented in the framework to capture the damage propagation within the constituents of composite materials. A representative volume element (RVE) containing randomly distributed fibers is modeled using the Component-Wise approach (CW), an extension of CUF beam model based on Lagrange type polynomials. The efficiency of the proposed numerical framework is achieved through the ability of the CUF models to provide accurate three-dimensional displacement and stress fields at a reduced computational cost.
Analysis of Meshing Characteristics of Pins and Pin Housing Integral Structure in Cycloidal Planetary Drive
Authors: Wang Yukun , Liu Guanyi , Yu Hao , Mao He , He Kai , Du Ruxu
Published: January 2018

Precision reducer is one of the key parts of an industrial robot, which generally incorporates cycloidal planetary drive. Engagement of the cycloidal wheel and the pins causes rolling friction between the wheel and the pins as well as sliding friction between the pins and the pin housing in the traditional cycloidal transmission of the reducer. In this paper, we present a new kind of design to make the pins and the pin housing a whole structure, thereby the cost of manufacturing and assembly can be significantly reduced. And in this new structure, we only need to consider sliding friction between the cycloidal wheel and the unibody of the pins and pin housing. The difference between the new structure and the conventional structure in the meshing properties was given. In addition, we used finite element method to analyze the friction and contact stress between the cycloidal wheel and the pins in the actual working condition, and compared it with the traditional structure. The simulation results proved the feasibility of the new structure and provided a theoretical basis for further design and manufacturing of this new kind of cycloidal planetary drive structure.
Study of Damping Properties of Polymer Matrix Composites Through Wave Propagation
Authors: Kulkarni Shank S. , Tabarraei Alireza
Published: January 2018

We conduct a stochastic analysis to investigate the damping properties of polymer composites with viscoelastic matrix and elastic spherical inclusions. Since damping capability of polymer composites is directly related to the ratio of loss to storage modulus known as tan δ, we use computational homogenization techniques to investigate the effect of vibrational frequency, size and volume fraction of inclusions on tan δ. Our results show that tan δ is highly dependent on the frequency of vibrations as well as the volume fraction of inclusions. Our numerical analyses also show that tan δ is not sensitive to the size of inclusions as long as inclusions volume fraction remains the same.
A Comparison of Flat White Aerosol and Rhodamine (R6G) Fluorescent Paints and Their Effect on the Results of Tomographic PIV Measurements
Authors: Bisel Tucker T. , Dahlberg Jerry L. , Martin Tony R. , Owen Spencer S. , Keanini Russell G. , Tkacik Peter T. , Narayan Nithin , Goudarzi Navid
Published: January 2018

Methods for reducing surface reflections during PIV measurements are commonly discussed, but the effects of those surface reflections on PIV measurements are generally neglected. In this study, a comparison of light gathering characteristics of an experimental tomographic PIV system is made using a bluff body model that is coated: i) first, with a commercially available flat white aerosol paint and ii) second, with an airbrushed Rhodamine (R6G) fluorescent paint. For each coating, PIV measurements are compared from flow regions that are affected by either direct or indirect reflections. Measurements show that very little incident light is absorbed at white boundaries, producing strong light reflection; this effect, in turn: i) saturates the light signal from far-removed suspended particles and ii) greatly reduces the signal-to-noise ratio for particles situated even close to the receiving optics. By contrast, Rhodamine (R6G) fluorescent paint provides excellent surface reflection mitigation when paired with the 532 nm filters, producing a signal-to-noise ratio sufficient to allow uniform imaging of particles across the entire calibrated volume.
A Leak Localization Model for Gas-Liquid Two-Phase Flows in Nearly Horizontal Pipelines
Authors: Figueiredo Aline B. , Sondermann Carina N. , Patricio Rodrigo A. C. , Bodstein Gustavo C. R. , Rachid Felipe B. F.
Published: January 2018

In the oil industry the localization of a leak that occurs in a pipeline is an important piece of information that needs to be obtained before mitigating actions can be taken to remedy the leak effects. In this paper we are particularly interested in testing a leak localization model for two-phase flows based upon the intersection of the hydraulic grade lines emanating from the pipeline ends. This methodology is commonly applied to single-phase-flows. In two-phase flows, the flow-pattern that develops along the entire pipeline upstream and downstream of the leak strongly affects the pressure gradient and has significant influence on the location of the leak. We consider this two-phase flow to be steady and to occur in a nearly horizontal pipeline characterized by the stratified-flow pattern. We also assume that the flow is isothermal with a compressible gas phase and an incompressible liquid phase. The results of the numerical simulations allow the model sensitivity to be studied by changing the leak location, for a given leak magnitude. From this analysis, we may observe how these parameters affect the pressure gradients along the pipeline that develop upstream and downstream of the leak and the model’s ability to predict the leak location.
A Novel Design of Flexure Based, Shape Memory Alloy Actuated Microgripper
Authors: Sanaani Yosri Taha , Alshorman Ahmad , Alshurman Khaled
Published: January 2018

In this paper, a novel design of a simple, compactly structured, and easy to fabricate microgripper is presented. Stainless steel (St 304) is used as a structural material of the microgripper whereas Shape memory alloy (Ni-Ti) wires are used as actuators. Novel design of microgripper device is presented where two shape memory alloy actuators are used; the first actuator is used to close the gripper jaw whereas the second actuator is used to increasing the opening stroke. The linear and small change in the length of the shape memory alloy (SMA) wire turns into large jaw displacement through flexure hinges (complaint mechanism). In order to develop a microgripper with maximum gripping stroke (jaw displacement) corresponding to minimum stress on flexure hinges, the finite element (FE) analysis using Comsol Multiphysics5.2a software is used to optimize the structural design of the proposed microgripper. Also, stress and displacement finite element analysis are presented for the optimized design of the microgripper. Finally, short comparison between the new design and the previous ones shows better results in terms of increasing the gripper stroke, reducing the stresses on the gripper joints, and conducting new mechanism.
Study of the Formation of Long Period Stacking Ordered Phases in Sputtered Thin Film Mg-Gd-Zn Alloys
Authors: Yarmolenko Sergey , Galdamez Kevin , Neralla Sudheer , Xu Zhigang , Pai Devdas , Sankar Jagannathan
Published: January 2018

Formation of long-period stacking ordered (LPSO) phases can significantly improve mechanical and corrosion properties of Mg-alloys. Typically LPSO phases can be formed by quick solidification of Mg-alloys having at least two alloying elements with atomic radii higher and lower than that of Mg. Stability of LPSO phases greatly depend on amounts and ratio of alloying elements. We report formation of thin film LPSO structures produced by co-sputtering of magnesium with zinc and gadolinium having less than 10% of alloying elements. This method allows controlling the ratio of the elements in composition, deposition temperature and orientation of thin films. Pure Mg, Zn and Gd films and their alloys deposited at temperatures below 200°C have HCP Mg-based crystallographic structure with exclusively basal orientation. LPSO phases and their stacking period were detected by observation of laminar structure patterns in low-angle x-ray reflectometry scans. The study of effects of elemental composition, deposition temperature and post-annealing of room temperature-deposited films on the formation of LPSO phase showed that the co-sputtering method can be very useful and efficient for the screening of new LPSO phases without the considerable expense preparation of bulk alloy preparation.
Film Cooling Effectiveness Comparison on Turbine Vane Endwall With Cluster Configurations Using PSP Measurement Technique
Authors: Chowdhury Nafiz H. K. , Shiau Chao-Cheng , Han Je-Chin , Xu Hongzhou , Fox Michael
Published: January 2018

Film cooling performance comparison on a turbine vane endwall with two different cluster configurations incorporating upstream inlet leakage flow was studied by applying PSP measurement technique. Experiments were conducted in a blow-down wind tunnel cascade facility at the exit isentropic Mach number of 0.5 corresponding to inlet Reynolds number of 380,000, based on axial chord length. A freestream turbulence level was generated as high as 19% with an integral length scale of 1.7 cm at the inlet of vanes’ leading edge plane. The results of each design and the comparison are presented in two-dimensional adiabatic film cooling effectiveness distributions on the endwall surface as well as the corresponding laterally averaged distributions. The focus of this study is to compare two different endwall cooling designs by the parametric effect of coolant-to-mainstream mass flow ratio (MFR) and density ratio (DR) on film cooling effectiveness. Initially, increased MFR for the endwall cooling and upstream leakage levels up the local film cooling effectiveness and yields improved coverage on the endwall. However, the endwall and upstream leakage demonstrate different behavior, while highest MFR does not provide any improvement as endwall cooling is suffered from the jet lift-off, highest MFR from the upstream leakage shows a monotonic increasing effectiveness on the endwall. On the other hand, the DR effect on effectiveness reveals different trend at a different design. Under a given amount of coolant supply and a fixed number of cooling hole, the comparison results really emphasize the importance of the cooling hole arrangement as one of the proposed cluster design can properly cover the whole endwall area.
Using Surface Characterization for Engineering Education Laboratories
Authors: Mauk Michael G. , Chiou Richard Y. , Kadapa Shraman , Ertekin Yalcin , Tseng Tzu-Liang (Bill)
Published: January 2018

A suite of surface measurement methods are described, assessed and compared for several types of materials of technological interest including silicon for solar cells, machined metal surfaces, and rapid prototyped (e.g., 3d-printed) plastic parts. We describe student laboratory projects for surface roughness characterization using different techniques including depth gauge, stylus profilometer, atomic force microscope (AFM), glossmeter, LED light scattering, laser light scattering, image processing, and wetting angle measurements. This provides instructive case studies for learning concepts of surface characterization and metrology, comparing information gained by different measurement techniques, gauge reproducibility and repeatability, optimizing post-processing in rapid prototyping, and issues for adapting measurements for automated and in-line quality assurance.
An Internet-of-Things Based Framework for Collaborative Manufacturing
Authors: Krishnamurthy Rajesh , Cecil J. , Perera Damith
Published: January 2018

The exchange of data and information among collaborating partners and resources in a distributed manufacturing system assumes significance especially in today’s global economy. In recent years, Internet of Things (IoT) and Cyber Physical Systems (CPS) related practices and technologies have emerged as enablers of collaborative manufacturing and engineering practices. Smart technologies involving Virtual Reality and haptic based interactions are continuing to play an important role in concurrent engineering based methods in distributed contexts. The research presented in this paper explores the design of an IoT based framework for electronics manufacturing involving the use of VR based environments and Cloud computing technologies. The process domain of interest is electronics manufacturing with an emphasis on Surface Mount assembly of printed circuit boards (PCBs). The VR based assembly environment played a key role in this IoT framework as it supported Concurrent Engineering practices by enabling stakeholders in this manufacturing system context to obtain a better understanding of the manufacturing process design while providing ‘what if’ analysis capabilities for changing customer requirements. Another benefit of such VR based IoT frameworks is the potential of such 3D environments to provide effective training of assembly processes as well as facilitating better understanding of process design issues from distributed locations.
Experimental Study of Drag Reduction on Superhydrophobic Surfaces Using Quartz Crystal Microbalance (QCM)
Authors: Esmaeilzadeh Hamed , Zheng Keqin , Su Junwei , Mead Joey , Sobkowicz Margaret J. , Sun Hongwei
Published: January 2018

A durable superhydrophobic coating formulation with epoxy binder thermoset was used to coat on surfaces, which provide high quality for corrosion protection, reduced biofouling and improved hydrodynamic behavior. The single and double layers coating of these nanostructured epoxy were fabricated and coated on a novel quartz crystal microbalance (QCM) technique to investigate their hydrophobic properties. Different static and dynamic wettability were obtained and characterized by evaluating the electrical impedance of QCM coated with nanostructured epoxy in air and DI water. It was found that QCM is able to quantitatively characterize the hydrophobicity of these nanostructured polymer surfaces. For double layer coating, the frequency shift in DI water was smaller in comparison to the single layer one. The reduction in mechanical impedance of QCM clearly demonstrates the effect of enhanced hydrophobicity for both single and double layers. The experimental results show that the hydrophobic surface resulted in smaller mechanical impedance loading, while the hydrophilic surface exerted much larger mechanical impedance. The outcome of this research will build a solid foundation for the further improvement of vehicles coated with superhydrophobic surfaces operating in water and increased equipment life.
Ride Comfort Evaluation Using Brain Activity in the Prefrontal Cortex Induced by Discomfort During Horizontal Vibration
Authors: Kaede Kazunori , Arakawa Yuta , Muramatsu Keiichi , Watanuki Keiichi
Published: January 2018

In this study, we measured brain activity using near-infrared spectroscopy (NIRS) when a person was feeling discomfort caused by vibrations. We used the variance in oxygenated hemoglobin (oxy-Hb) levels as an evaluation index. Correlation coefficients were derived from the results of brain function measurements and sensibility evaluation of discomfort using a questionnaire. As a result, a high negative correlation was observed between discomfort and both vibration and brain activation around the medial prefrontal cortex, and a high positive correlation was observed between discomfort and both vibration and brain activation around the lateral prefrontal cortex. This suggests the possibility of evaluating discomfort on the basis of brain activation.
The Effect of a Quarter-Circle Corner Crack on the Distribution of the SIF Along the Front of a Non-Aligned Semi-Elliptical Surface Crack in an Infinitely Large Plate Under Uniaxial Tension
Authors: Levy C. , Perl M. , Ma Q.
Published: January 2018

The evaluation of the mutual effect of non-aligned multiple cracks is a prerequisite in applying fitness-for-service codes. For non-aligned parallel cracks, during on-site inspection, one needs to decide whether the cracks should be treated as coalesced or separate multiple cracks for Fitness-for-Service. In the existing literature, criteria and standards for the adjustment of multiple nonaligned cracks are very source dependent, and those criteria and standards are often derived from on-site service experience without rigorous and systematic verification. Based on this observation, the authors previously reported on the influence of an embedded crack on an edge crack in 2-D scenarios and, more recently, in 3-D scenarios of the influence of a surface crack on a quarter-circle corner crack. However, realistic crack configurations detected using non-destructive methods are generally 3-D in nature and their influences are mutual. Thus the SIF distribution characteristics along the surface crack is equally important as the SIF distribution of the corner crack when Fitness-for-Service rules are to be applied. Therefore, non-aligned flaws with different configurations and shapes and the SIFs along their crack fronts are deemed necessary in order to obtain more practical guidance in the usage of rules speculated in Fitness-for-Service codes. In this study, the characteristics of the SIF distribution along a semi-elliptic non-aligned surface crack is examined under the influence of a quarter-circle corner crack of various geometries in an infinitely large plate. For any given geometry of a quarter-circle corner crack, a pair of horizontal (H) and vertical (S) separation distances between the two cracks is chosen followed by a detailed analysis of the effect of the quarter-circle corner crack on the 3D SIFs of the surface crack at different ellipticities. The analysis is repeated for various combinations of separation distances S and H. The results from this study are collectively significant to the understanding of the correlation between the criteria and standards in Fitness-for-Service community and the consequence of their usage in engineering practice.
Experimental and Numerical Investigations of the 3-D Turbulent Flow Characteristics Around Submerged Permeable Breakwaters
Authors: Stanley Caleb , Etsias Georgios , Dabelow Steven , Dermisis Dimitrios , Zhang Ning
Published: January 2018

Submerged breakwaters are favored for their design simplicity in projects intended to dissipate wave energy and reduce erosion on coastlines. Despite their popularity, the effects that submerged breakwaters exhibit on the surrounding hydrodynamics are not clearly understood, mainly due to the flow complexity generated from 3-dimensional turbulent structures in the vicinity of the breakwaters that affect the mean flow characteristics and the transport of sediment. The objective of this study was to evaluate the effects that various geometric designs of submerged permeable breakwaters have on the turbulent flow characteristics. To meet the objective of this study, laboratory experiments were performed in a water-recirculating flume, in which the 3-dimensional velocity field was recorded in the vicinity of scaled breakwater models. Breakwaters that were tested include non-permeable, three-hole, and ten-hole models. The experimental data obtained was compared to results obtained from numerical simulations. Results demonstrated that permeable breakwaters exhibit more vertical turbulent strength than their non-permeable counterparts. It was also discovered that three-hole breakwater models produce higher turbulent fluctuations than that of the ten-hole breakwaters. The results from this study will be used eventually to enhance the performance of restoration projects in coastal areas in Louisiana.
Development and Experimental Characterization of Metal 3D-Printed Scalable Swirl Stabilized Mesoscale Burner Array
Authors: Rajasegar Rajavasanth , Mitsingas Constandinos M. , Mayhew Eric K. , Liu Qili , Lee Tonghun , Yoo Jihyung
Published: January 2018

The development of a mesoscale burner array capable of sustaining stable, clean, and compact flames suited for a variety of applications with performance and emission characteristics comparable to that of existing large scale burners is presented. The proposed architecture offers significant improvements in flame stability, by minimizing susceptibility to extinction, while maintaining high combustion efficiency and low emission levels under ultra-lean operating conditions for a wide range of combustion power outputs. A prototype 4×4 mesoscale burner array was designed and manufactured using Direct Metal Laser Sintering process (DMLS). The combustor array operates on gaseous fuel (methane) and employs a combination of swirl and bluff body for flame stabilization. The mesoscale burner array can sustain ultra-lean flames with lean blow off limits (LBO) of around ϕ = 0.65 independent of combustor power output that ensures adequate scalability. Thermocouple measurements indicated minimal element-to-element temperature variations with measured temperatures reaching adiabatic flame temperature levels indicating reduced heat loss due to increased flame interaction. Combustion efficiencies, about 98%, were estimated using Gas Chromatography-Mass Spectrometry (GCMS) analysis of the exhaust gas. The detected levels of combined unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions were well below 0.1% by mass. Thus, the potential for an optimized mesoscale architecture which can be seamlessly scaled over a wide range of combustor power outputs capable of powering large scale gas turbines to compact portable units without any performance deterioration or loss in power to weight ratio has been successfully demonstrated.
Gender Issues in Engineering Education: What Systemizing and Empathizing Have to Do With It
Authors: Fertig Jan , Kumpaty Subha
Published: January 2018

More than half of U.S. students entering college are female, but female students are still largely absent from engineering fields. The persistent absence of females in engineering may owe itself, at least in part, to a fundamental difference in cognitive approaches between males and females. Although there is a significant amount of cross-over, males are more likely than females to have a systemizing brain, which is associated with a drive to understand how the world works through the identification and creation of patterns and rules. Females are more likely to be born with an empathizing style, which lends itself to a natural aptitude for identifying others’ thoughts and emotions. This systemizing-empathizing dichotomy is based on the work of Simon Baron-Cohen at the University of Cambridge in the UK. Engineering programs are geared toward those with a higher SQ (systemizing quotient). This paper reviews relevant research on how systemizing-empathizing (S-E) theory applies to engineering education and examines current research on the reasons behind the dearth of females in engineering, finding that the contemporary engineering culture in college is also characterized by subtle forms of discrimination that systematically direct women away from engineering. Finally, some recommendations are made for how engineering programs might engage a broader base of students.
Flow Analysis Through a High-Performance SI-Engine Cylinder Head Intake Port
Authors: Welling Andrew , Mueller Donald , Lucas Paul
Published: January 2018

The use of spark-ignited (SI) production-style vehicle engines in high-performance applications is a growing trend in the aftermarket performance industry. However, the use of economically designed components, specifically cylinder heads, presents challenges when used in this manner. The study of flow through a cylinder head is a topic of extensive research where complex flow patterns have made modelling and computer simulation challenging. A variety of approaches have been employed including simplifying model assumptions, different boundary conditions, different meshing strategies, and different turbulence models. The focus of this research is modification of the air intake port geometry of a VR38DETT engine in order to increase the volumetric flow rate past a current limit of 330.4 CFM at 0.700” valve lift, which has been achieved by porting methods alone. Using SolidWorks, a computational fluid dynamics model was developed, verified, validated, and analyzed. The modelling methodology was verified using a mesh convergence study of the pressure drop along a pipe with a bend. Also, the bend loss coefficient was compared to published values for different ratios of the centerline radius of the bend to the internal pipe diameter. The model was then validated using steady-state flow bench test data. Results of the analysis indicate that the cylinder head can achieve a flow rate 5.15% above the current limit when the port geometry is enlarged and the short-side radius is increased, only in support of a cooling passage geometry change.
Numerical and experimental thermal analysis of polyimide-based x-ray masks at the Canadian Light Source
Authors: Achenbach Sven , Shen Chen , Wells Garth
Published: January 2018

In deep x-ray lithography (DXRL), synchrotron radiation is applied to transfer absorber patterns on an x-ray mask into thick photoresist to generate high quality microstructures. Fabrication of the required x-ray masks is a demanding process sequence and constitutes a bottleneck in DXRL technology. Polymer-based mask membranes offer many benefits during mask fabrication and operation, but usually suffer from large thermal distortions during x-ray exposure. These are due to the low thermal conductivity of most polymers (approximately 0.2 W/m K), which results in inefficient heat transfer to the cooled areas around mask and substrate. The power tuning capabilities at the Synchrotron Laboratory for Micro and Nano Devices beamline, Canadian Light Source, however, allow the beam power to be adjusted and consequently limit thermal distortions. In this study, x-ray masks based on 30 μm thick polyimide membranes are studied. Numerical simulations of the thermal and thermoelastic behavior were performed using the software package ansys r14.5. The beam power input parameters were calculated with the software lex-d. For experimental verification, a process to fabricate simple test masks was developed. The polymer membranes were processed on stainless steel sacrificial wafers and were patterned with 80 μm thick nickel absorbers in two macroscopic layouts. Five chromel/alumel (K-type) thermocouples where then bonded to the absorbers to measure the heat distribution. The measurements generally validated the numerical results. The simulated thermal distributions consistently overestimate the experimental values by approximately 4–6 K, which is mainly attributed to uncertainties in the experimental proximity gap settings. The thermal simulation results indicate that the dominant heating mechanism of the resist is conduction: Energy absorbed in the mask absorbers is conducted through the helium gas in the proximity gap to the nonexposed poly(methyl methacrylate) (PMMA) areas and the substrate (cooled to 18 °C). For 500 μm thick PMMA resist, exposed with a synchrotron beam power of 19.6 W, maximum temperatures in the mask are 31.0 and 25.8 °C in the resist below. Maximum single-axis resist deformations in the mask plane amount to 4.12 μm. At 250 μm resist thickness, the observed temperatures are only 25.4 °C in the mask and 22.3 °C in the resist, with maximum mask plane deformations of about 2.3 μm. Integrated over the entire absorber size of 60 mm, these deformations roughly double. Local structure accuracy results were obtained by measuring distortions in a micropatterned polyimide mask. Deformations verify simulation results, vary with the position on the layout, and scale with the incident beam power. At 3.3 W incident beam power, typical deformations around 1–1.5 μm and maximum deformations of 2.3 μm were measured in 100 μm thick resist.
Rapid drug screen using 3D tumor organoids
Authors: Chung Kwanghun
Published: January 2018

Breast cancer organoids enable high-throughput functional drug screens to potentially guide individualized therapy.