bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimum Tick Collection Material and Design for Autonomous Tick Collection Robot
Authors: Harrison Moretto Caroline “Niki” , Dong Janet , Qiu Yesiliang
Published: February 2021

This paper discusses the design and testing material utilized to collect ticks from rugged terrain in remote areas via a mobile robot using a mast system, focusing on locating the ideal design and material to ensure maximum tick collection without impacting mobility. Drags are used to collect ticks from short grass, and flags, in the air along the side of the robot, are used to collect ticks from tall grass and shrubs. The design was tested in the field and a laboratory. Cotton and sponge cloth materials were evaluated, along with the shape of the material.

The optimum design uses strips of rough sponge cloth to collect ticks. The roughness and fibrous nature of the material increase the number of ticks collected and performed the best of all materials tested. Seams in the sponge cloth allow them to tear away from the robot, if they become tangled in brush, to prevent the robot from being incapacitated. The thickness and weight of the sponge cloth also discourage the material from knotting and entangling with the robot or the environment.

The flag attachment points are adjustable horizontally to allow the rearrangement of strips for optimum tick collection. Each strip is designed for independent removal to contain ticks easily and replace strips quickly.

Attaching sponge cloth flagging and dragging strips to a mobile robot for tick collection protects humans from a potential illness from bugs and insects carrying disease pathogens, injury from traveling across rough ground, and harm due to exposure to the elements; productivity is also increased. The collection strips should capture ticks despite adverse conditions, be easily interchangeable, and not hinder the tick collection and removal process.
Dynamics of MEMS-Based Angular Rate Sensors Excited via External Electrostatic Forces
Authors: Gebrel Ibrahim F. , Wang Ligang , Asokanthan Samuel F.
Published: February 2021

This paper investigates the dynamic behavior of rotating MEMS-based vibratory gyroscopes which employs a thin ring as the vibrating flexible element. The mathematical model for the MEMS ring structure as well as a model for the nonlinear electrostatic excitation forces are formulated. Galerkin’s procedure is employed to reduce the equations of motion to a set of ordinary differential equations. Understanding the effects of nonlinear actuator dynamics is considered important for characterizing the dynamic behavior of such devices. A suitable theoretical model to generate nonlinear electrostatic force that acts on the MEMS ring structure is formulated. Dynamic responses in the driving and the sensing directions are examined via time responses, phase diagram, and Poincare’ map plots when the input angular motion and the nonlinear electrostatic force are considered simultaneously. The analysis is envisaged to aid fabrication of this class of devices as well as for providing design improvements in MEMS Ring-based Gyroscopes.
Distributed Sensor System for Underground Fuel Storage Facility Monitoring and Leak Detection
Authors: Nakamura Matthew , Hafner Noah , Brown Joseph J.
Published: February 2021

This work presents a sensor system to monitor environmental conditions in the vicinity of fuel storage tanks and facilities, providing measurements to help assess tank integrity and identify spills or leaks. The system utilizes a common hardware platform for multiple functional areas (e.g. base stations and sensing nodes) in the sensor network, simplifying manufacturing and logistics. The hardware platform was designed for low-cost manufacturing, adaptability, and versatility. It uses commercial off-the-shelf electronics in 3D-printed enclosures that were designed to optimize sensor and communication antenna placement. Pairing this hardware platform with a web-based data storage system and display client provides real-time telemetry visualization for monitoring tank facility conditions and can alert operators of potential leaks and hazards. The sensor system provides advances over current techniques in the form of scalability, cost minimization, live data reporting, and localization for active monitoring. Modularity reduces the engineering effort for adaptations to use new sensors in diverse environments, which can have different factors that lead to failures, and also allows the system to be updated as technology progresses. Data collected in experimental testing validates system functionality and ability to detect factors associated with spills and leaks.
Data-Driven Constitutive Modeling of the Progressive Softening in Elastomeric Gels With Interpenetrating Networks
Authors: Morovati Vahid , Ghaderi Aref , Dargazany Roozbeh
Published: February 2021

Solid though hydrogels are a class of bio-inspired elastomeric material with the ability of high stretch-ability, toughness, and water absorption. Though hydrogels exhibit nonlinear features such as stress softening, permanent set, cyclic energy dissipation and induced anisotropy in their mechanical responses. Besides, gels used in biomedical devices and soft robots are designed to sustain continuous cyclic loading during their service-life. While most studies assume that the majority of stress softening occurs in the first cycle. However, experimental studies suggest that the material exhibits damage accumulation and stiffness reduction significantly at higher number of cyclic loading. This progressive stress softening can lead to an unpredicted response of the material in dynamic loading as it is a function of material stiffness. However, there are only a few constitutive models developed to address this accumulative damage in the elastomeric gels. Thus, here, we developed a data-driven method to predict the behavior of hydrogels subjected to a high number of cycles. The developed model can be particularly used to estimate material response in each cycle and its steady-state response due to three-dimensional deformation. The strain energy of the material is the same in all direction in the undeformed state and damage evolve in each direction based on its maximum deformation. Moreover, the energy of the material in each direction estimated through two parallel artificial neural network. The proposed model shows good agreement with cyclic uni-axial tensile test data in different cycles of the loading and steady-state response of material.
Ultrasonic Acoustic Heterodyne Transmission Into the Human Auditory and Vestibular Systems
Authors: Dumm Christopher M. , Hiers Anna C. , Vipperman Jeffrey S. , Klinzing George E. , Balaban Carey D.
Published: February 2021

It is well-known that airborne sound induces vibration of the eardrum, the coupled middle ear bones, and the inner ear. Sound transmission to the inner ear is attenuated by damage or dysfunction in the eardrum or ossicular chain. Corrective devices often use contact shakers to directly vibrate the temporal bone of the skull, delivering sound. We investigate an alternative, noncontact method of sound transmission that uses ultrasonic signals to transmit sound into the auditory and vestibular systems. Minimal literature exists describing ultrasonic hearing, largely due to attenuation of air-conducted frequencies above 20 kHz. High-amplitude airborne sound incident upon the skull can induce temporal bone system vibrations along an unconventional structural path. Finite-element-based acoustic modeling of the auditory and vestibular anatomy reveals resonant behavior in structural components of the middle and inner ear at ultrasonic frequencies. These “built-in sound amplifiers” can be leveraged to compensate for impedance mismatches experienced in airborne ultrasound transmission. By heterodyning (amplitude modulating) a targeted ultrasonic carrier signal with an audio signal, the nonlinearities of acoustic propagation and the auditory and vestibular sense organs allow interpretation of heterodyne signals. These techniques provide a foundation to improve a wide variety of communication equipment, including hearing aids, without interfering with balance sensations.
Discrete Vortex Modeling of a Flapping Foil Energy Harvester With LEV Shedding Criterion
Authors: Kamrani Fard Kiana , Liburdy James A.
Published: February 2021

The energy harvesting performance of a flapping airfoil is studied through discrete vortex model. Results are obtained for a thin flat airfoil that undergoes a sinusoidal flapping motion for reduced frequencies of k = fC/U∞ = 0.06–0.16 where f is the heaving frequency of the foil, C is the chord length and U∞ is the freestream velocity. The airfoil pitches about the mid-chord and the heaving and pitching amplitudes of the airfoil are h0 = 0.5C and θ0 = 70° respectively, as these numbers have been shown to give optimal energy harvesting results for a rigid airfoil. The study applies a panel-based discrete vortex model that incorporates a leading edge suction parameter criterion to understand the flow behavior around the airfoil. The leading edge suction parameter is found from 2D CFD simulations (Navier-Stokes equations solved in Fluent) for all K values. A correlation between the critical leading edge suction parameter and reduced frequency is found from the identified critical LESP values. An empirical trailing edge separation correction is also applied to the transient force results since flow separation at the trailing edge is anticipated. The parameters of interest from the model are transient distributions of force, power output, and overall efficiency. Model results are then validated against 2D CFD simulations. The effect of reduced frequency on power production and overall efficiency is finally studied to identify the optimal reduced frequency for energy harvesting applications.
Determining Micro Droplet Profile Using Internal Reflection Interference Fringes
Authors: Kim Iltai Isaac , Li Yang , Park Jaesung
Published: February 2021

We introduce an optical diagnostics to determine the morphological features of liquid droplet such as the thickness, the contact angle, and the dual profile using internal reflection interferometry. A coherent laser beam is internally reflected on the air/liquid interface of a sessile droplet placed on a prism-based substrate to produce an interference fringe on a screen far from the substrate. The reflected laser rays consist of the reflection from the center spherical droplet profile and the one from the lower hyperbola-like droplet profile. The reflected rays are interfered each other to form the interference fringes. Ray tracing simulation is conducted using a custom-designed computer program. The simulation shows that the interfering rays reflected near the inflection point produce the outer-most fringes of the concentric interference pattern on the screen, and the reflected rays from the apex of the spherical profile and the contact line of the lower hyperbola-like profile construct the fringes at the center of the interference patterns. The simulated results are compared with the experimental observation to show a good agreement in the number and the location of the fringes and the radius of the outer-most-fringe where the number of the fringes is dependent on the droplet thickness and the radius of the fringe depends on the contact angle of the droplet. This result provides a new measurement technique to determine the morphological features of very small microdroplet such as the thickness (< a few micron thickness), the contact angle (< a few degree), and the dual-surface profile.
A Sequential Two-Step Design Framework for Deformable Mechanical Metamaterials
Authors: Patiballa Sree Kalyan , Krishnan Girish
Published: February 2021

Deformable metamaterials are materials that are made up of several repeating elastic building blocks whose geometries can be tailored to obtain a specified global shape change or stiffness behavior. They are deemed useful in soft robotics, shape morphing mechanisms, stretchable electronics, wearable devices, and devices that adapt according to their environment. This paper presents a two-step sequential design framework for the synthesis of deformable mechanical metamaterials where (a) topology optimization is used to map global deformation requirement to local elasticity matrix, followed by (b) a selection of building block microstructure geometry from a database and refining it to match the elasticity requirement. The first step is accomplished through a unique parameterization scheme that enables the classification of the planar orthotropic elasticity matrix into four distinct classes. The second step uses a kinetostatic framework known as load flow visualization to populate candidate microstructure geometries within these four classes. Finally, the framework is validated for the design of a cantilever beam with a specified lateral stiffness requirement and the design of planar sheets that exhibit sinusoidal deformation patterns.
Design and Construction of a Posterior Walker for Older Adults “Moviclinic”
Authors: Garrido Silva Gianina , Arguello Espinosa Juan Manuel , Maradey Lázaro Jessica Gissella , Bayona Velasco Geidy Alexandra , Suescun Mejia Angela Dayana
Published: February 2021

In recent years, the population of older adults (i.e age over 65) will double from 11% to 22% according to statistics from the World Health Organization (i.e WHO).

The assistive devices for gait (i.e Assistive Devices and Mobility Aids, ADMA) allow the movement and mobility of people with reduced abilities to walk, providing additional support of the human body to the ground. Some authors have classified these devices as fixed and mobile. Fixed devices are made up of parallel bars or handrails and mobile devices that include walking sticks, crutches, and walkers.

Especially, mobile devices allow the gait to be carried out by leaning on the device so that the patient will have greater stability and balance; as well as autonomy on regular terrain. Likewise, these reduce the risk of complications such as falls and immobilizations, which greatly improves the patient’s functionality and in rehabilitation can help to reduce pain in the muscles and joints by redistributing weight.

The “Moviclinic” rear walker is made up of a metal frame, equipped with forearm support and a front safety stop, which provides security for the user and his family. The rear wheels allow to direct the element and with the front wheels regulates the speed. Besides, it has an obstacle detection system which is based on the ultrasound principle, generating an audible alarm when detecting them with two priority levels, and the alarm system activated directly by the user. This feature always allows both the user and his family or caregiver to have peace of mind at all the times. Electronic design is also included.

This article aims to show the design, construction and validation of a support device for elderly patients with gait disturbances called “Moviclinic” based on the application of the “Design Thinking” methodology, Finite Element Analysis (FEA) and a technological surveillance analysis to make a comparison with current walkers and be able to offer a quality, efficient and affordable product. Finally, the test protocols carried out and the results obtained when testing their operation.
A Modified Network Alteration Model to Predict Quasi-Static Behavior of the Cross-Linked Polymers During Hydrolytic Aging
Authors: Bahrololoumi Amir , Mohammadi Hamid , Morovati Vahid , Dargazany Roozbeh
Published: February 2021

The network alteration theory is utilized to capture the effects of hydrolytic aging on the mechanical integrity of the polymer matrix. Hydrolytic degradation generally considered as a result of two simultaneous chemical phenomena; (i) reduction of the cross-links, and (ii) active chain loss. Assuming the alteration of the chain density is identical to the change of the number average molecular weight along the aging trajectory, the strain energy of polymer matrix can be rewritten as a function of deformation, deformation history, storage time, and aging temperature. The proposed model includes only five physically inspired material parameters. Thus, while it is computationally efficient, it shows good agreement with own experimental data, which performed on various range of accelerated aging temperatures and times. With respect to its computational efficiency, simplicity, accuracy, and interpret-ability, the model is a good choice for advanced implementations in FE programs.
Development of a Mobile Platform for Wheat Phenotyping
Authors: Pour Majid Khak , Fotouhi Reza , Hucl Pierre
Published: February 2021

Designing and implementing an affordable High-Throughput Phenotyping Platform (HTPP) for monitoring crops’ features in different stages of their growth can provide valuable information for crop-breeders to study possible correlation between genotypes and phenotypes. Conducting automatic field measurements can improve crop productions. In this research, we have focused on development of a mechatronic system, hardware and software, for a mobile field-based HTPP for autonomous crop monitoring for wheat field. The system can measure canopy’s height, temperature, vegetation indices and is able to take high quality photos of crops. The system includes developed software for data and image acquisition. The main contribution of this study is autonomous, reliable, and fast data collection for wheat and similar crops.
Mass Transfer Rate Enhancement in Sparged Vessel for Ammonia-Water Nano-Fluid in VARS by Adding Nanoparticles
Authors: Bhujbal Rahul , Nakate Sanjay , Dingare Sunil V.
Published: February 2021

The refrigeration systems are used in domestic and commercial freezing applications. These systems are needed to be used energy efficiently to get the economic operation condition. The vapor compression refrigeration cycle (VCR) is getting replaced by vapor absorption refrigeration system (VARS) as they can use low grade energy. This VARS can be used by making use of waste energy in the form of heat which is readily available for many applications. Performance of the VARS is dependent on the generator and absorber performance. In absorber it is based on the amount of refrigerant absorbed and the solution flow rate. Experimental and Numerical study of bubble absorber and effect of nanoparticle on ammonia water mass transfer is carried out. In this study, different designs for the absorber chamber are viewed and compared together, based on the research did earlier. Looking at the aspects of bubble type absorber designs, these designs give better mass transfer performance as compared to other designs. These designs may be improved to get the energy efficient design of the absorber. Present study includes the enhancement of mass transfer rate by the addition of nanoparticles using aluminum oxide (Al2O3). Here, sparged vessels with NH3-H2O binary fluid are arranged with varying percentage of nanoparticle (Al2O3). This study includes the study of mass transfer enhancements by using nanoparticles. Based on the experimental results carried out for the varying mass flow rates it is found that the mass transfer rate is enhanced significantly, it is because the interfacial area is enhanced by the addition of nanoparticles to the base fluids.
Increased Efficiency in Spontaneously Passing Kidney Stones Using a Novel Ureteral Double-J Stent
Authors: Amiri Manouchehr , Amiri Sorosh
Published: February 2021

Kidney stones are stiff deposit minerals formed in the kidneys. In patients with kidney stones disease, double-J stents are used to increase the openness of the ureter in case of blockage by the kidney stones. The stent surfaces are normally smooth with symmetric friction along the longitudinal axis. In this work, we show that a modified double-J stent with asymmetric friction surface facilitates passage of stone fragments after extracorporeal shock wave lithotripsy or trans ureteral lithoclast. To examine the effect of asymmetric friction on the stone passing efficiency, finite element simulations were conducted. Simulation results revealed that at excitation vibration frequency of 0.15 Hz the stone unidirectionally moves along the stent at an average speed of 0.03 cm/s which is a significant increase compared to the clinical reports. Practically, the asymmetric friction can be made by laser micro-engraving techniques such as the same method in CD writing.
Effect of China Clay on Mechanical Properties of AA7075/B4C Hybrid Composite Fabricated by Powder Metallurgy Techniques
Authors: Pandey Krishna Murari , Manohar Guttikonda , Maity Saikat Ranjan
Published: February 2021

Composite materials are very predominant in the areas of industrial applications, aerospace and defense sectors. Aluminium metal matrix composites are main targeted materials by many researchers because of its low density, high strength, corrosion resistance and economical that makes material suitable for aerospace and automobile sectors. In this work effect of china clay volume fraction on mechanical properties of AA7075/B4C composite was investigated. Effect of china clay volume fraction on mechanical properties was analyzed with the help of results obtained by XRD, tensile, compression and micro hardness tests. From the experimentation analysis and results it was clear that added china clay acts as effective binder material for efficient compaction and ejection of green compacts from the die material after cold compaction processes and gives high strength to the composite material up to 7% volume fraction in sintered composite while in tensile strength after that material strength starts to degrade. In this work critical volume fractions of china clay in AA7075/B4C composite was investigated in tensile, compression and hardness. Further, effect of heat treatment on mechanical properties of the composite material was investigated.
Topology Optimization of the Hip Bone for Walking Using Multi-Load Approach
Authors: Eswara Sai Kumar Kandula , Rakshit Sourav
Published: February 2021

In this work, we use structural topology optimization to design the hip bone with multi-load conditions of walking gait cycle. Previous research works on optimal bone design primarily aimed to design the micro-structure of the femur bone using a multi-load approach with global geometry fixed. To the best of authors’ knowledge, no optimal design research literature is available on the hip bone. This work uses the concept of multiload conditions, since it considers the effect of entire gait cycle while applying loading conditions. We consider three cases for the weights. Those are (i) equi-weight case, (ii) non-equi weight case based on the fraction of the phase in the gait cycle and (iii) non-equi weight case based on the ratio of magnitude of the hip joint force in respective phases to the total hip joint force of the entire walking gait cycle. The optimal designs are compared with natural hip bone by measuring shape similarity using Procrustes Analysis. Results show that the compliance is less for the optimal designs compared with natural hip bone. The shape similarity values for the three cases are found to be 64%, 78% and 73% respectively. Optimal design obtained from the non-equi weight case based on the duration of phase has highest shape similarity value due to creation of a hole similar to obturator foramen in lower portion of the hip bone. The maximum stress and maximum displacement values are lower in optimal designs compared with natural hip bone. From the shape similarity results, the optimal design from the non-equi weight based on duration of the phase may be more suitable for prosthesis applications.
Virtual Fixturing: Inspection of a Non-Rigid Detail Resting on 3-Points to Estimate Free State and Over-Constrained Shapes
Authors: Lindau Björn , Wärmefjord Kristina , Lindkvist Lars , Söderberg Rikard
Published: February 2021

When the geometry of a non-rigid part or pre-assembly is measured fully clamped (over-constrained) in a measurement fixture, the spring-back information and influence from gravity forces are usually lost in the collected data. From the 3D-measurement data, it is hard to understand built in tensions, and the detail’s tendency to bend, twist and warp after release from the measurement fixture. These effects are however important to consider when analyzing each part’s contribution to geometrical deviations after assembly.

In this paper a method is presented, describing how free state shape and over-constrained shape of a measured detail can be virtually estimated starting from acquired data when the part or the preassembly is resting on only 3-points. The objective is to minimize the information loss, to spare measurement resources and to allow for a wider use of the collected data, describing the geometry.

Part stiffnesses, part to part contacts and gravity effects are considered in the proposed method. The method is based on 3D-scanning techniques to acquire the shape of the measured object. Necessary compensations for part stiffnesses and gravity effects are based upon Finite Element Analysis (FEA) and the Method of Influence Coefficients (MIC).

The presented method is applied to an industrial case to demonstrate its potential. The results show that estimated over-constrained shapes show good resemblance with measurements acquired when part is over-constrained in its measurement fixture.
A New and Efficient Meshless Computational Approach for Transient Heat Conduction in Anisotropic Nonhomogeneous Media: Fragile Points Method and Local Variational Iteration Scheme
Authors: Guan Yue , Grujicic Rade , Wang Xuechuan , Dong Leiting , Atluri Satya N.
Published: February 2021

A new and efficient computational approach is presented for analyzing transient heat conduction problems. The Fragile Points Method (FPM) utilized for spatial discretization can, on one hand, like many other meshless methods, be free of the requirement of high-quality meshing, and on the other hand, bypass the difficulty of domain integration problem which is commonly seen in Galerkin meshfree methods. With local, polynomial and discontinuous trial and test functions, the method has a great potential in solving problems with rupture and fragmentation without remeshing. Anisotropy and nonhomogeneity which is challengeable for many spatial numerical methods do not give rise to any difficulties in the present implementation. The Local Variational Iteration Method (LVIM) in the time domain is a highly efficient technology in solving nonlinear problems, in which the time steps can be an order of magnitude larger than the traditional backward Euler scheme and the computing time can be cut by a half. The FPM+LVIM solver is also connected to the prepossessing module of ABAQUS which helps generating the domain partition. It shows the compatibility of the current approach with various partitions and makes it more friendly for engineer users. Several 2D and 3D numerical examples with functionally graded and composite materials are then provided as validations.
Metal Forming With Laser Origami: Parameter Analysis and Optimization
Authors: Ma Peiwen J. , Hao Yue , Lien Jyh-Ming , Peraza Hernandez Edwin A.
Published: February 2021

Laser origami is a metal forming process where an initially planar sheet is transformed into a target three-dimensional (3D) form through cutting and folding operations executed by a laser beam. A key challenge in laser origami is to determine the locations of the cuts and folds required to transform the planar sheet into the 3D target shape. The region of the planar sheet that can be transformed into the target shape through these cuts and folds is denoted as the net. This paper presents a method to determine optimal net(s) for laser origami based on criteria including minimum energy usage, minimum fabrication time, minimum error in the fold angles, and minimum material usage. The 3D target shape is given as a polygonal mesh. To generate a net, each edge in the mesh must be classified as a cut or a fold. The energy, time, and other parameters associated with cutting or folding each edge are determined using experimentally calibrated formulas. A search algorithm is subsequently implemented to find combinations of cut and folded edges that provide an optimal set of nets for the given 3D target shape based on a cost function. Nets that are disconnected or have overlapping regions are discarded since they are invalid for laser origami. The method is demonstrated by applying it to different target shapes and cost functions.
Study of the Cutting Parameters on Surface Roughness and Material Removal Rate in Hard Turning of UHMWPE
Authors: Aguilera-Ojeda César Oswaldo , Saldaña-Robles Alberto , Vidal-Lesso Agustín , Martínez-Ramírez Israel , Aguilera-Gómez Eduardo
Published: February 2021

The surface finish of industrial components has an important role in their performance and lifetime. Therefore, it is crucial to find the cutting parameters that provide the best surface finish. In this work, an experimental study of the effect of cutting parameters on ultra-high molecular weight polyethylene (UHMWPE) by a turning process was carried out. Today, the UHMWPE polymer continues to find applications mainly in the automotive industry and biomechanics because it is resistant to impact and corrosive materials to use. A face-centered Central Composite Design (CCD) and Response Surface Methodology (RSM) were applied to evaluate the influence of the cutting speed (Vc), feed rate (f) and depth of cut (ap) of the turning operation on the Average Surface Roughness (Ra) and Material Removal Rate (MRR). Results allowed obtaining an adjusted multivariable regression model that describes the behavior of the Ra that depends on the cutting parameters in the turning process. The predictive model of Ra showed that it fits well with a correlation coefficient (R2) around 0.9683 to the experimental data for Ra. The ANOVA results for Ra showed that the feed is the most significant factor with a contribution of 42.3 % for the term f 2, while the speed and depth of cut do not affect Ra with contributions of 0.19% and 0.18%, respectively. A reduction of feed from 0.30 to 0.18 mm·rev−1 produces a decrease in surface roughness from 6.68 to 3.81 μm. However, if the feed continued to reduce an increase in surface roughness, a feed of 0.05 mm·rev−1 induces a surface roughness of 14.93 μm. Feeds less than 0.18 mm·rev−1 cause a heat generation during turning that increases the temperature in the process zone, producing surface roughness damage of the UHMWPE polymer. Also, the results for MRR demonstrated that all of the cutting parameters are significant with contributions of 31.4%, 27.4% and 15.4% to feed, speed, and depth of cut, respectively. The desirability function allowed optimizing the cutting parameters (Vc = 250 m·min−1, ap = 1.5 mm y f = 0.27 mm·rev−1) to obtain a minimum surface roughness (Ra = 4.3 μm) with a maximum material removal rate (MMR = 97.1 cm3·min−1). Finally, the predictive model of Ra can be used in the industry to obtain predictions on the experimental range analyzed, reducing the surface roughness and the manufacturing time of UHMWPE cylindrical components.
Scanning Strategies in the PBF Process: A Critical Review
Authors: Malekipour Ehsan , El-Mounayri Hazim
Published: February 2021

The powder-bed fusion (PBF) process is capable of producing near-fully dense metallic parts; however, various defects — particularly thermal abnormalities — can still be observed during the process. Some of these thermal defects — cracks, distortion, delamination of layers, and microporosity — cannot be removed by post-processing operations. The majority of these abnormalities are the result of residual stress, heat accumulation, lack of inter-track /inter-layer bonding, lack of powder fusion, or a combination of these factors. Modifying the scanning strategy (the topology of scanning tracks) can efficiently mitigate these abnormalities by adjusting the process parameters and adopting proper scanning patterns.

The implementation of different scanning strategies significantly changes the ultimate quality of printed parts and manufacturing process lead time. Choosing a proper scanning strategy minimizes the residual stress and internal porosity, generates homogeneous microstructure, and avoids heat accumulation throughout the part during the printing process.

In this work, we conducted a critical review of different scanning strategies, their pros and cons, limitations, and influence on the resulting properties of fabricated parts. Furthermore, we report the latest efforts for improvement of the current scanning strategies and introduce the-state-of-the-art strategies in the multi-laser PBF (ML-PBF) process. The insights provided here can assist scholars in evaluating existing scanning strategies and scanning patterns, and in identifying ways both to overcome scanning limitations and to modify them. On the other hand, it can assist manufacturers in selecting the best scanning strategies for their products based on their designs, demands, and resources.
Control Co-Design for Rotor Blades of Floating Offshore Wind Turbines
Authors: Du Xianping , Burlion Laurent , Bilgen Onur
Published: February 2021

This paper aims to demonstrate the application of control co-design methodology for the rotor blades of a floating offshore wind turbine. A 10 MW reference wind turbine model is utilized in the co-design framework. In this paper, the coupling effect between the system, defined by the pre-cone angle, and the controller, defined by pitch angle, is analyzed with a parametric study. The system parameters of the blade are identified by exciting the system with a step input, and by using the step response. The identified model is used to demonstrate the coupling effects of the structural parameters. The control co-design process is implemented to reduce the blade root bending moment by controlling the pitch angle as a function of the pre-cone angle. Utilizing the 10 MW reference model, the proposed control co-design method can reduce the blade root bending moment and attenuate transverse vibrations faster than the original design. Compared to a sequentially designed controller, the co-design demonstrated reduction of the blade root bending moment with similar attenuation time.
Generating Pseudo-Data to Enhance the Performance of Classification-Based Engineering Design: A Preliminary Investigation
Authors: Du Xianping , Bilgen Onur , Xu Hongyi
Published: February 2021

Machine learning for classification has been used widely in engineering design, for example, feasible domain recognition and hidden pattern discovery. Training an accurate machine learning model requires a large dataset; however, high computational or experimental costs are major issues in obtaining a large dataset for real-world problems. One possible solution is to generate a large pseudo dataset with surrogate models, which is established with a smaller set of real training data. However, it is not well understood whether the pseudo dataset can benefit the classification model by providing more information or deteriorates the machine learning performance due to the prediction errors and uncertainties introduced by the surrogate model. This paper presents a preliminary investigation towards this research question. A classification-and-regressiontree model is employed to recognize the design subspaces to support design decision-making. It is implemented on the geometric design of a vehicle energy-absorbing structure based on finite element simulations. Based on a small set of real-world data obtained by simulations, a surrogate model based on Gaussian process regression is employed to generate pseudo datasets for training. The results showed that the tree-based method could help recognize feasible design domains efficiently. Furthermore, the additional information provided by the surrogate model enhances the accuracy of classification. One important conclusion is that the accuracy of the surrogate model determines the quality of the pseudo dataset and hence, the improvements in the machine learning model.
A Preliminary Study of Combined Heat and Power in a Facility
Authors: Jaladi Divya , Languri Ethan , Cunningham Glenn
Published: February 2021

Rapid economic growth has increased the need for efficient electrical and thermal usage worldwide to not only save in energy but also be competitive in industry. Optimization of the current energy sources ought to be carried out in order to minimize the use of fossil fuels in the coming decades in a manner that is economically feasible. Cogeneration of electricity and heat, also known as combined heat and power (CHP), is one such technique making efficient use of fuel and providing greater power output while making the energy infrastructure of facilities more resilient. This technology is primarily useful in large ind40ustrial or medical centers, as they have a greater proportion of thermal loads than residential or office units. This paper reports a preliminary study at a facility in Tennessee, USA, to determine the cogeneration feasibility and its payback period. This study shows how the calculations are carried out by considering the primary energy consumption costs for determining the modeled payback periods and basic measures to be taken into consideration for a CHP installation at interested facilities.
Enhancing the Steel Tube Manufacturing Process With a Zero Defects Approach
Authors: Sousa João , Ferreira José , Lopes Carlos , Sarraipa João , Silva João
Published: February 2021

The continuous thrive for working safety, customer satisfaction and increasing profits for companies has led to numerous manufacturing and management strategies. One of the most promising strategies nowadays is Zero Defects that focuses on the elimination of defected parts in the manufacturing processes. The benefits of Zero Defect implementation in the manufacturing industry are mainly related to the reduction of scrap material, and everything that does not bring any added value to the product. The result is a reduction of the company’s expenditure for dealing with defective products. In spite the concept not being new, the practical application of such strategies were limited by technological constraints and high investment costs. With the Industry 4.0 evolution, some Zero Defects concepts are more accessible due to the availability of sensors and data related techniques such as Machine Learning and Big Data although a lot of work is still required for component integration to enhance the capability of the heterogeneous technologies.

The quality of the steel tubes is evaluated by sampling and relies on the expertise of the operators for checking for nonconformities. When a defect is detected, the process parameters are adjusted based on prior experience. However, since this is a continuous process, the delay between the appearance of a defect in the process and its awareness leads to a considerable amount of produced scrap material. Worst-case scenario, the defective product can be delivered to the customer damaging the customers trust and leading to additional replacement costs. This paper addresses the application of the Zero Defects approach to the steel tube manufacturing industry. This approach is part of the Zero Defects Manufacturing Platform EU project that is based around a Service Oriented Architecture and microservices approach capable of building, running and managing specific use-case oriented software applications called zApps. The Zero Defects methodology to design a zApp based on key criteria for the steel tube industry is described. Additionally, the envisioned zApps to monitor all the produced steel tube during the manufacturing process are detailed. The inspection systems uses a scanning camera and a laser profile scanner to capture the steel tube defects during manufacturing and prior to packaging. Although the ultimate goal is to eliminate the cause of the defective products, the objective of the zApp is to increase the number of detections of defective products based on industry standards and reduce the amount of generated scrap material.
Numerical Simulations and Validation of Engine Performance Parameter in Direct Injection Spark Ignition (DISI) Engines Using Chemical Kinetics
Authors: Arshad Muzammil
Published: February 2021

Experimental studies have been augmented by computer modelling and simulations for the development and optimization of future fuels and automotive engines. Traditional reliance on the simplified global reactions for combustion simulations reduces the credibility of the prediction of combustion and engine performance parameters, such as in-cylinder pressure, heat release and pollutant formation. The study of engine performance parameters helps in improving the performance as well as the reduction of emissions in the engines. The present study has used detailed chemistry by augmenting the combustion model of a three-dimensional unsteady compressible turbulent Navier-Stokes solver with liquid spray injection by coupling its fluid mechanics solution with detailed kinetic reactions solved by a commercial chemistry solver. A skeletal reaction mechanism was reduced to study the in-cylinder pressure in a direct injection spark ignition (DISI) engine. Sensitivity analysis was performed to reduce the reaction mechanism for the compression and power strokes utilizing computational singular perturbation (CSP) method. An interface was developed between fluid dynamics and chemical kinetics codes to study iso-octane that is a well-established surrogate fuel for gasoline. Gasoline is a complex mixture of various compounds and hydrocarbons. The study used 90% iso-octane and 10% n-heptane as surrogate fuel because this combination best modelled the results. A mesh independent study was performed at stoichiometric conditions that validated and showed a good agreement of peak in-cylinder pressure against the experimental data for a direct injection spark ignition (DISI) engine. This study has been comprehensive as it includes a detailed study performed for premixed case at ϕ = 0.98 and 1.3 as well as stoichiometric condition in a direct injection spark ignition (DISI) engine, that resulted in the development of a reduced mechanism that has the capability to validate in-cylinder pressure and heat release rate from stoichiometric to rich mixtures for premixed cases in a spark ignition engine. The study concludes that it is imperative to establish a library of reduced mechanisms for various spark ignition engines as well as other combustion systems.
Epitaxial growth of 3C-SiC film by microwave plasma chemical vapor deposition in H2-CH4-SiH4 mixtures: Optical emission spectroscopy study
Authors: Yurov V. Yu. , Ralchenko V. G. , Martyanov A. K. , Antonova I. A. , Sedov V. S. , Khomich A. A. , Voronov V. V. , Savin S. S. , Shevchenko M. Y. , Bolshakov A. P.
Published: February 2021

Microwave (MW) plasma in silane-hydrogen and silane-hydrogen-methane mixtures is used effectively for chemical vapor deposition of Si, SiC, diamond, and SiC-diamond composite films; however, the properties of such plasma at pressures of the order of 100 Torr remain largely unexplored. Here we characterize the MW plasma (2.45 GHz) in SiH4 + H2 and SiH4 + СH4 + H2 mixtures (72 Torr) with silane content ranging from 0% to 5% in the process gas using high-resolution optical emission (OE) spectroscopy. Besides the OE lines of C2 dimer, Balmer series of excited atomic hydrogen (Hα, Hβ, Hγ, Hδ, and Hε), and CH radical, we observed atomic Si lines at 263, 288, and 391 nm and a relatively weak SiH emission. Gas temperature Tg of ≈3160 K is assessed from the rotational structure of the C2 dimer (Δν = 0, λ = 516.5 nm) emission band, and the absorbed microwave power density (MWPD) in the plasma fluctuates in the narrow range between 36 and 43 W/cm3 with a slight tendency to decrease with silane addition. The MWPD, intensity ratio Hα/Hβ of hydrogen Balmer series lines (related to excitation temperature Texc), and Si lines’ intensities in OE spectra as functions of SiH4 concentration in H2 and H2 + CH4 mixtures all show an extremum or a kink in slope near a special point at ≈0.5% SiH4. Finally, we produced a silicon carbide film of cubic polytype 3C-SiC on a (111) oriented Si substrate, which was characterized with Raman spectroscopy and x-ray diffraction, and its monocrystalline structure was confirmed.
Microrheology reveals simultaneous cell-mediated matrix stiffening and fluidization that underlie breast cancer invasion
Authors: Krajina Brad A. , LeSavage Bauer L. , Roth Julien G. , Zhu Audrey W. , Cai Pamela C. , Spakowitz Andrew J. , Heilshorn Sarah C.
Published: February 2021

Invading breast cancer cells transform the mechanics of their surroundings across a panorama of time scales.
Antibiotic Susceptibility of Clinical Burkholderia pseudomallei Isolates in Northeast Thailand from 2015 to 2018 and the Genomic Characterization of
β
-Lactam-Resistant Isolates
Authors: Hii Shirley Yi Fen , Tandhavanant Sarunporn , Phunpang Rungnapa , Ekchariyawat Peeraya , Saiprom Natnaree , Chewapreecha Claire , Seng Rathanin , Thiansukhon Ekkachai , Morakot Chumpol , Sangsa Narongchai , Chayangsu Sunee , Chuananont Somchai , Tanwisaid Kittisak , Silakun Wirayut , Buasi Noppol , Chaisuksant Seksan , Hompleum Tanin , Chetchotisakd Ploenchan , Day Nicholas P. J. , Chantratita Wasun , Lertmemongkolchai Ganjana , West T. Eoin , Chantratita Narisara
Published: February 2021

Melioidosis is an often fatal infection in tropical regions caused by an environmental bacterium,
Burkholderia pseudomallei
. Current recommended melioidosis treatment requires intravenous β-lactam antibiotics such as ceftazidime (CAZ), meropenem (MEM), or amoxicillin-clavulanic acid (AMC) and oral trimethoprim-sulfamethoxazole.
Predicting the Disposition of the Antimalarial Drug Artesunate and Its Active Metabolite Dihydroartemisinin Using Physiologically Based Pharmacokinetic Modeling
Authors: Arey Ryan , Reisfeld Brad
Published: February 2021

Artemisinin-based combination therapies (ACTs) have proven to be effective in helping to combat the global malaria epidemic. To optimally apply these drugs, information about their tissue-specific disposition is required, and one approach to predict these pharmacokinetic characteristics is physiologically based pharmacokinetic (PBPK) modeling.
Stress-Induced Block in Dicarboxylate Uptake and Utilization in Salmonella enterica Serovar Typhimurium
Authors: Hersch Steven J. , Radan Bojana , Ilyas Bushra , Lavoie Patrick , Navarre William Wiley
Published: February 2021

Bacteria have evolved to sense and respond to their environment to maximize their chance of survival. By studying differences in the responses of pathogenic bacteria and closely related nonpathogens, we can gain insight into what environments they encounter inside of an infected host.
Glucan Unmasking Identifies Regulators of Temperature-Induced Translatome Reprogramming in C. neoformans
Authors: Bloom Amanda L. M. , Goich David , Knowles Corey M. , Panepinto John C.
Published: February 2021

Cryptococcus neoformans
is a fungal pathogen that causes devastating morbidity and mortality in immunocompromised individuals. It possesses several virulence factors that aid in its evasion from the host immune system, including a large polysaccharide capsule that cloaks the antigenic cell wall.
Supplemental Material: Magnetostratigraphy of U-Pb–dated boreholes in Svalbard, Norway, implies that magnetochron M0r (a proposed Barremian-Aptian boundary marker) begins at 121.2 ± 0.4 Ma
Authors: Zhang Yang , Ogg James G , al. et
Published: February 2021

Additional details on paleomagnetic analyses of core DH1, supplemental Figures S1–S3, and Tables S1–S5.