bluuebunny/crossref_metadata_2025 huggingface dataset:
Knowledge-Driven Based Performance Analysis of Robotic Manufacturing Cell for Design Improvement
Authors: Kangru Tavo , Mahmood Kashif , Otto Tauno , Moor Madis , Riives Jüri
Published: February 2021

Manufacturing companies must ensure high productivity and low production cost in rapidly changing market conditions. At the same time products and services are evolving permanently. In order to cope with those circumstances, manufacturers should apply the principles of smart manufacturing together with continuous processes improvement. Smart manufacturing is a concept where production is no longer highly labor-intensive and based only on flexible manufacturing systems, but production as a whole process should be monitored and controlled with sophisticated information technology, integrated on all stages of the product life cycle. Process improvements in Smart Manufacturing are heavily reliance on decisions, which can be achieved by using modeling and simulation of systems with different analyzing tools based on Big Data processing and Artificial Intelligence (AI) technologies.

This study was performed to automate an estimation process and improve the accuracy for production cell’s performance evaluation. Although there have been researches performed in the same field, the substantial estimation process outcome and accuracy still need to be elaborated further.

In this article a robot integrated production cell simulation framework is developed. A developed system is used to simulate production cell parametric models in the real-life situations. A set of rules and constraints are created and inserted into the simulation model. Data for the constraints were acquired by investigating industries’ best production cells performance parameters. Information was gathered in four main fields: company profile and strategy, cell layout and equipment, manufactured products process data and shortcomings of goal achievements or improvement necessary to perform. From those parametric case model, a 3D virtual manufacturing simulation model is built and simulated for achieving accurate results.

The integration of manufacturing data into decision making process through advanced prescriptive analytics models is a one of the future tasks of this study. The integration makes it possible to use “best practice” data and obtained Key Performance Indicators (KPIs) results to find the optimal solutions in real manufacturing conditions. The objective is to find the best solution of robot integrated cell for a certain industry using AI enabled simulation model. It also helps to improve situation assessment and deliberated decision-making mechanism.
Study on Natural Vibration Characteristics Based on the Coupled Wave Theory of Spring Supported Elastic Pipes and Fluids
Authors: Tokunaga Takeshi , Mori Koji , Kadowaki Hiroko , Saito Takashi
Published: February 2021

A gradient of a blood flow velocity on the surface of a blood vessel is one of the clinical medicine concerns from the view point of prevention of the arteriosclerosis.

In previous study, we formulated a relationship between the pressure and a flow velocity based on the coupled wave theory of elastic pipes and Newtonian fluids [1]. In addition, a flow velocity distribution and a wall shear stress are estimated by using the blood pressure data, which are non-invasively obtained by the tonometry method. This method is quasi-analytical method to apply the coupled wave theory for industrial flow field inside steel pipes proposed by Urata [4] to blood vessel, and has the advantage of systematic estimator compared with the numerical calculation. However, the coupled wave theory has applied to the elastic pipes that were assumed to be infinitely long. In addition, a single wave was assumed to be dominant within the elastic pipes and the Newtonian fluids. Therefore, in order to apply various length vessels in clinical field, the boundary of the blood vessels that varies from site to site, and the natural vibration characteristics that depend on the boundary conditions, could not be reflected in the wall shear stress estimation. In general, in order to solve the forced vibration with the boundary condition, it is necessary to clarify natural frequency and natural mode as natural vibration characteristics of structure.

In this study, we introduce the spring supported elastic pipes to the coupled wave theory and formulated a relationship between the natural vibration characteristics and the boundary conditions. In this proposed method, the spring-supported elastic pipe has a feature that can be treated as an arbitrary boundary condition of an artery by giving an appropriate spring coefficients. Therefore, it is easy to apply to various types of blood vessels clinically. By investigating the natural vibration characteristics of blood vessels that varies from site to site, it may be possible to clarify fluctuations of blood flow in response to blood pressure with some frequency-bands. In addition, natural angular frequencies and natural modes of the spring supported elastic pipes and the Newtonian fluids were estimated for general blood vessel based on the coupled wave theory. In the result, the natural angular frequencies and the natural modes that reflect the clinical vibration characteristics to some extent can be estimated. On the other hand, particular modes may not reflect boundary condition, and further examination of the relationship between natural vibration characteristics and boundary condition is needed.
Beam Hardening Artifact Reduction in X-Ray CT Reconstruction of 3D Printed Metal Parts Leveraging Deep Learning and CAD Models
Authors: Ziabari Amirkoushyar , Venkatakrishnan Singanallur , Kirka Michael , Brackman Paul , Dehoff Ryan , Bingham Philip , Paquit Vincent
Published: February 2021

Nondestructive evaluation (NDE) of additively manufactured (AM) parts is important for understanding the impacts of various process parameters and qualifying the built part. X-ray computed tomography (XCT) has played a critical role in rapid NDE and characterization of AM parts. However, XCT of metal AM parts can be challenging because of artifacts produced by standard reconstruction algorithms as a result of a confounding effect called “beam hardening.” Beam hardening artifacts complicate the analysis of XCT images and adversely impact the process of detecting defects, such as pores and cracks, which is key to ensuring the quality of the parts being printed. In this work, we propose a novel framework based on using available computer-aided design (CAD) models for parts to be manufactured, accurate XCT simulations, and a deep-neural network to produce high-quality XCT reconstructions from data that are affected by noise and beam hardening. Using extensive experiments with simulated data sets, we demonstrate that our method can significantly improve the reconstruction quality, thereby enabling better detection of defects compared with the state of the art. We also present promising preliminary results of applying the deep networks trained using CAD models to experimental data obtained from XCT of an AM jet-engine turbine blade.
An Innovative Approach to CTCs’ Liquid Surgery
Authors: Fontanili Luca , Milani Massimo , Montorsi Luca , Scurani Letizia , Venturelli Matteo , Fabbri Francesco
Published: February 2021

Circulating Tumor Cells (CTCs) can be defined as cancerous cells, which detach from a tumor and flow through the vascular or lymphatic systems. The blood flow can carry the tumor cells in another region of human body where they can become the starting point for the growth of additional metastases. Because of this behavior, in the CTCs study it is paramount to acquire new data and knowledge to understand the mechanisms that lead to the separation of the cell from the tumor as well as the major characteristics of these cells. The aim of this work is the development of an innovative therapeutic and diagnostic approach able to lead to a new medical device for removing CTCs from the peripheral blood of a patient. The main target of the approach is to detect the CTCs and separate them during a conventional extracorporeal circulation procedure, similar to that used for renal failure. In this work, the CTCs physical properties are investigated in order to explore the possible characteristics that can be exploited in an ad-hoc developed medical device to remove them from the blood flow. The CTCs physical properties are analyzed numerically, and their behavior is studied by means of CFD simulations. The preliminary numerical tests have been carried out on simple geometries in order to assess the influence of magnetic and electric fields on tumor cells’ trajectory. These results are the baseline information to develop more complicated geometries and prototypes for real operations.
Human Thoracolumbar Spine Tolerance to Injury and Mechanisms From Caudo-Cephalad Impacts
Authors: Yoganandan Narayan , Khandelwal Prashant , Porwal Vaibhav , Humm John
Published: February 2021

The human thoracolumbar spinal column sustains axial loading under physiological and traumatic loading situations. Clinical studies have focused on the former scenario, and the investigation of low back pain issues and spinal stabilization using artificial devices such as arthroplasty are examples. Investigative studies have largely used quasi-static and vibration loading on the spine segment(s) and spinal columns. The traumatic loading scenario is relatively less researched, and it is a dynamic event. Injuries under this scenario occur in sports, automotive, and combat environments. Impact vectors include flexion-extension modes in automotive crash events. Vertical or caudal to cephalad oriented impacts have been identified in both automotive and military scenarios. Frontal impacts to restrained occupants in the automotive and underbody blast impacts from improvised explosive device in combat situations are examples of the vertical loading vector. Although some studies have been conducted using whole body human cadavers and isolated spinal columns, determinations have not been made of the injury risks and stress and strain responses for a variety of accelerative pulses. The aims of the present investigation were to delineate the internal biomechanics of the spinal column under this impact vector and assess the probability of injury. Male and female whole-body human finite element models were used in the study. The occupants were restrained and positioned on the seat, and caudo-cephalad impacts were applied to the base. Different acceleration-time profiles (pulse durations ranging from 50 to 200 ms and peak accelerations varying from 11 g to 46 g) were used as inputs in both male and female models. The resulting stress-strain profiles in the cortical and cancellous bones were evaluated at different vertebral levels. Using the peak transmitted forces at the thoracolumbar disc level as the response variable, the probability of injury for the male spine was obtained from experimental risk curves for the various accelerative pulses. Results showed that the shorter pulse durations and rise times impart greater loading on the thoracolumbar spine. The analysis of von Mises stress and strain distributions showed that the compression-related fractures of vertebrae are multifaceted with contributions from both the cortical and cancellous bony components of the body. Profiles are provided in the body of the paper for different spinal levels. The intervertebral disc may be involved in the fracture mechanism, because it acts as a medium of load transfer between adjacent vertebrae. Injury risks for the shortest pulse was sixty-three percent, and for the widest pulse it was close to zero, and injury probabilities for other pulses are given. The present computational modeling study provides insights into the mechanisms of the internal load transfer and describe the injury risk levels from caudal to cephalad impacts.
Evaluating the Effect of a Student-Centered Pedagogical Approach on Students’ Skills and Knowledge in Computer-Aided Design (CAD) Course
Authors: Peng Xiaobo , Jackson Malcolm , Duan Chang , Han Mingli , Yalvac Bugrahan , Hing Ebony Lai , Ketsetzi Antonia , Eseryel Deniz
Published: February 2021

This paper presents a quasi-experimental pre and post test design to explore the effects of a student-centered pedagogical approach in Computer-Aided Design (CAD) education. In this study, students in experimental group generated CAD screencast tutorials, recorded the supporting audio, shared the videos with their peers, and provided feedback to each other’s screencast. A life-long learning survey, an engineering attitude survey, and a CAD modeling exam were used as the study instruments. Students’ learning outcomes were evaluated by analyzing data collected over five years from 17 classrooms. Findings indicated that first generation college students or female students were more receptive to the student centered instructional approaches and they improved their life-long learning skills and engineering attitudes. We observed a strong evidence that when students designed screencast exercises, their CAD exam performance improved. This study also contributes to our knowledge on how to effectively assess engineering attitudes and life-long learning skills.
Experimental Study of Multiple Air Jets Impinging a Moving Flat Plate
Authors: Barbosa Flavia , Teixeira Senhorinha , Costa Carlos , Marques Filipe , Teixeira José Carlos
Published: February 2021

The motion of the target plate is important in some industrial applications which apply multiple jet impingement, such as reflow soldering, drying and food processing. Multiple jet impingement is widely used due to its ability to generate high heat transfer rates over large and complex areas. This convective process is characterized by several flow interactions essentially due to adjacent jets mixing prior the impingement, wall jets collision after the impingement, as well as crossflow interactions induced by the motion of the wall jets that flow through the exits of the domain. These interactions lead to strong flow recirculation, pressure gradients and boundary layer development. However, the complexity of the flow interactions is increased with the surface motion in confined space, due to the generation of strong shear regions. These interactions can induce problems and product defects due to complicated thermal behavior and non-uniform heating or cooling, being important to fully understand the process in order to reduce time and costs. This work addresses the experimental analysis of multiple air jets impinging on a moving flat plate. The experiments are conducted on a purpose-built test facility which has been commissioned, using a 2D-PIV system. Through this technique, the flow structure and velocity profiles will be analyzed in detail. The effects of the impinging plate motion on the resulting global and local velocity profile is compared with a static flat plate. The multiple jet configuration consists on air flowing through 14 circular nozzles, at a Reynolds number of 690 and 1,380. The experiments are conducted for a nozzle-to-plate distance of 8 and a jet-to-jet spacing of 2. The target plate motion remains constant throughout the experiments and equal to 0.03 m/s. The results are compared for both stationary and moving flat plates cases and express the increased complexity of the flow due to strong interaction between jets and the target surface, which affects the heat transfer performance. The results obtained experimentally are important to clearly define this complex flow and these data can be used in future works for numerical model validation.
Ontologies As a Tool for Design and Material Engineers
Authors: Pigazzi Riccardo , Confalonieri Chiara , Rossoni Marco , Gariboldi Elisabetta , Colombo Giorgio
Published: February 2021

Functionally Graded Materials (FGMs), initially conceptualized in the ’80, have recently attracted a great research interest thanks to the advent of additive manufacturing (AM) technologies. AM permits to gradationally varying the spatial composition or porosity inside an object resulting in a corresponding spatial change in material properties. The data about this new class of materials are radically different from the traditional engineering materials and require information about the object geometry. Moreover, traditional methods for product design are not sufficient to represent heterogeneous objects. The full exploitation of these technologies requires the synergy of material science, product modeling and manufacturing domain. Ontologies can play a crucial role for the integration, making the information accessible and understandable to both experts from different domains and machines. In this paper, a prototypical ontology for the characterization of FGM objects is proposed. Firstly, an already existing FGM ontology is analyzed, highlighting shortcomings and possible improvements. Then, the new ontology is proposed, focusing on the classes and relationships for accommodating material knowledge and geometrical information. The core idea, retrieved from the literature on heterogeneous object representation and transposed in an ontological fashion, is based on the mapping between the geometrical 3D space and the n-dimensional material space. After presenting the new ontology, a benchmark case study is described to test the effectiveness of this approach along with some competency questions an engineer might be interested in. The proposed ontology represents a first, crucial building block for a more complex system aiming to support the communication and knowledge sharing among different actors in engineering.
Autonomous Drone Delivery From Airdrop Systems (ADDAS): Aerially Deploying Folding-Wing Drones for Ground Reconnaissance
Authors: Bluman James , Carter Vault Davonte , Soon Wei Kang , Talbott Ruth , Willis Jonathan , Kopeikin Andrew , Prosser Ekaterina
Published: February 2021

Extending the long-range capabilities of unmanned aerial systems (UAS) is paramount to protecting small Soldier teams operating in remote battlefield scenarios. Currently, many small Unmanned Aerial Systems (sUAS) reconnaissance assets have the range necessary to facilitate small-unit missions. The purpose of this paper is to detail the design and testing of a system that fills this capability gap by creating folding-wing drones designed to be aerially deployed from an airdropped dispenser. The dispenser is attached to the Joint Precision Airdrop System (JPADS), which is an autonomously navigated cargo delivery parafoil that can glide several miles, and which can land within 100 meters of its target. To employ the system, the dispenser is launched from a high-altitude aircraft. The system must survive the opening of the parachute in high speed forward flight and provide cushioning to the drones and other components. Once the JPADS navigates the dispenser to a predetermined altitude and distance from the intended reconnaissance area, the dispenser deploys multiple folding-wing drones. The soldiers on the ground can access the drones’ live video feeds through a handheld video transmitter. The system combines the precision navigation and information-transmission capabilities of the fixed wing drone with the long-range capabilities of the JPADS. With a commercial-off-the-shelf drone as the folding-wing aircraft platform, the team designed a wing connection hub that allows for rapid folding and unfolding of the drone’s wings, a separate canister for each drone within the dispenser, and a dispenser capable of interfacing with both the canisters and the JPADS. Though currently in the technology-demonstration phase of the project, the team envisions the system being fully autonomous from launch of dispenser to end of mission.
On Numerical Modeling of Equal Channel Angular Extrusion of Ultra High Molecular Weight Polyethylene
Authors: Vasylevskyi Kostiantyn , Miroshnichenko Kateryna , Buklovskyi Stanislav , Tsukrov Igor , Grover Hannah , Van Citters Douglas
Published: February 2021

Ultra high molecular weight polyethylene (UHMWPE) is widely used in biomedical applications, e.g. as a bearing surface in total joint arthroplasty. Recently, equal channel angular extrusion (ECAE) was proposed as a processing method to achieve higher molecular entanglement and superior mechanical properties of this material. Numerical modeling can be utilized to evaluate the influence of such important manufacturing parameters as the extrusion rate, temperature, geometry of the die, back pressure and friction effects in the ECAE of polyethylenes.

In this paper we focus on the development of efficient FE models of ECAE for UHMWPE. We study the applicability of the available constitutive models traditionally used in polymer mechanics for UHMWPE, evaluate the importance of the proper choice of the friction parameters between the billet and the die, and compare the accuracy of predictions between 2D (plane strain) and 3D models.

Our studies demonstrate that the choice of the constitutive model is extremely important for the accuracy of numerical modeling predictions. It is also shown that the friction coefficient significantly influences the punch force and that 2D plane strain assumption can become inaccurate in the presence of friction between the billet and the extrusion channel.
Energy Resource for a RFID System Based on Dynamic Features of Reddy-Levinson Beam
Authors: Babaei Alireza , Parker Johné , Moshaver Paria
Published: February 2021

Understanding the effect of design parameters on resonant frequency variation is a critically important aspect of piezoelectric energy harvester device design. As a first step in more accurately investigating the performance of a fixture designed for targeted RFID tag communication that also utilizes an energy harvesting application, this paper analyzes the variations in resonant frequency of a higher-order beam based on Reddy-Levinson theory (RLBT) under rotation effects. A long-term goal of this research is to implement an effective energy harvester on the RFID system. Part of the experimental RFID test fixture can be modeled as a beam (or beam element); thus, understanding the resonance frequency variations due to shear deformation and rotation effects is an important first step in obtaining information about the efficacy of the fixture in serving as an energy harvester. Investigating the performance of a beam also provides valuable information about the maximum power, frequency bandwidth, and tuning ability of the device that can be expected from an analogous energy harvester. For the first time, the resonant frequency variation of a rotating thick beam is investigated. Specifically, RLBT is used to verify the effects of shear deformation upon resonant frequency, and a coupled displacement field is utilized to enable tuning the potential piezoelectric energy harvester to low-input excitations by means of constraining translational and rotational movements of the system based on a linear constraint equation. Navier’s method as an analytical-numerical method is adopted to discretize the continuous system and to find resonant frequencies, respectively. Results reveal the significance of beam thickness and rotation effects of the proposed model for the purpose of minimizing energy usage. Current results are compared and verified numerically with available benchmarks to confirm a satisfactory level of accuracy. The proposed model, which is based on a coupled displacement field, can also be used to design other piezoelectric electro-mechanical-systems; e.g., vibration isolators, and vibration controllers. In other words, in an energy-scavenging system, a fundamental understanding of parameters affecting the resonant frequency can be accomplished through the presented analysis. The proposed model highlights the fact that, by adopting a proper speed factor, tuning the piezoelectric energy harvester to low-input excitations is possible. Additionally, it is observed that the rotation effect on the resonant frequency is more severe than effects of slenderness ratio. Finally, in this paper an improved model is proposed to capture the shear deformation effect, particularly for thick-beam energy harvesters, with the capability of tuning to low-input excitations.
Nonlinear Vibrations of Model PWR Fuel Assemblies: Part 1 — Experimental Setup and Measurements
Authors: Ferrari Giovanni , Franchini Giulio , Balasubramanian Prabakaran , Karazis Kostas , Amabili Marco
Published: February 2021

Nuclear fuel bundles in PWR reactors present vibrations due to coolant flow, which may result in fretting at the interface between the fuel rods and the retaining elements, named spacer grids (SGs). Seismic excitation may also occur during accidental events, such as earthquakes. In this perspective, forced vibration experiments were performed on a reduced-scale nuclear fuel bundle provided by Framatome Canada. The presence of partially loose fuel pellets inside the fuel rods was provided in the experiments. A maximum coolant flow of 5 meters per second was reached inside a water tunnel.

The identification of vibration parameters was attempted in the linear regime, through modal analysis, and in the nonlinear regime, through a single-degree-of-freedom method based on harmonic balance. The value of the equivalent damping parameter was shown to increase strongly with the amplitude of the excitation, thus acting in the direction of safety. The fuel bundle presents a peculiar softening vibration behavior in the nonlinear regime, with a marked decrease of the peak vibration frequency. The comparison with other recent experiments shows that the boundary conditions constituted by SGs have a predominant effect on stiffness and damping during nonlinear vibrations. Therefore, the characterization of the boundary conditions at the SGs was attempted by means of dedicated experiments.

Bending oscillations were tested in the frequency range between DC and 50 Hertz. Tests were repeated in presence and in absence of water. The resulting force-displacement loops clearly show the presence of hysteresis and of bilinear stiffness. The availability of a mathematical model for the stiffness and the damping at the boundary conditions will be indispensable for the future development of reduced-order models describing the vibrations of PWR fuel bundles.
Bearing Housing Design for Vibration Control, Using Tilting Pad Bearings Instead of Lemon-Bore Type on a Gas Turbine
Authors: Anil Chippa , Satheesh Aparna , Santhanagopalakrishnan Babu , Bielecki Marcin
Published: February 2021

Heavy duty gas turbines are usually equipped with hydrodynamic bearings which are either lemon-bore or tilting pad type. Baker Hughes legacy gas turbines use these two types of bearings, and its selection is based on 1) considering pros & cons from Rotor dynamics, 2) bearing performance, 3) bearing housing stiffness, 4) vibration detection & control. Non-contact probes are used to monitor the vibrations of rotor. Majority of legacy gas turbines are not equipped with these probes. Due to this fact, over the years it resulted in non-detection of dynamics & vibration issue, which caused frequent bearing replacement. As the increase in industry demand to apply and measure vibrations using non-contact probes on bearings, an effort was made by Baker Hughes to implement these on existing fleet units. Also, in order to increase rotor dynamics stability of low-pressure rotor, to improve bearing life and performance, effort was made to replace lemon-bore bearings with tilting pad. This paper demonstrates efforts made to design the titling pad which would fit within envelop of already available bearing housing. Bearing/shaft clearance, bearing performance, modification of bearing retainer clearances are the mandatory tasks which would be dealt in this study. The swap of bearing type, and its effect on whole gas turbine rotor dynamic stability, checking the frequency crossovers with Campbell diagram would also be dealt in this paper. This paper also focuses on assessment on oil passage routing, temperature & proximity probe instrumentation routing design. Re-design is performed by analyzing various configuration, assessing different sensitivity studies & validation of modified bearing housing from structural integrity, ultimate load capability, & split plane oil leakage retention and its comparison with baseline are most important aspects of finalization of this change, which will be showcased in this paper. Instrumentation routing was a critical task when the considering bearing replacement from lemon-bore to tilting pad. As lemon-bore type bearings just have an elliptical inner surface, it’s quite easy to install the thermocouples into a simple hole. But as replacement has tilting pads, the challenge is to instrument the pads without effecting their movement and functionality. Such best practices are also dealt in this paper. Comparison of tilting-pad with lemon-bore, considering the fixed shaft diameter, the retainer outer diameter of tilting pad is higher than lemon-bore. This effect has a change in bearing seat on bearing housing, thereby reducing the effective stiffness of the housing, and the reduced split plane surface. To tackle this situation, several sensitivities were executed, by re-modifying the bolts and bolt holes on the existing housing, without modifying the housing envelop.
Study on Relations Between Abnormal Vibration and Friction Characteristics of a Roller Depending on Water Content for Three Types of Fined Coal
Authors: Shimizu Yusuke , Kobayashi Akira , Watanabe Kazuhiro , Ohno Emi , Echizenya Makoto , Fujita Katsuhide , Mori Koji , Saito Takashi
Published: February 2021

In coal-fired power generation, it is necessary to pulverize coal, and a vertical roller mill with excellent crushing efficiency has become the mainstream. However, In the process of pulverization by compression and shear, abnormal vibrations, which are considered to be self-excited vibration, occurs rarely. As a method of reducing self-excited vibration, adding water has been empirically performed in the field. Since the powder state changes due to water addition, it is necessary to investigate how the vibration characteristics and slip characteristics change. In this paper, we examined the effects of adding water to Artificial coal, Sub-bituminous coal A, and Sub-bituminous coal B with different powder characteristics on the dynamic friction characteristics and dynamic response generated between the roller and the powder. Investigating the relation between the RMS value of the horizontal acceleration response and the slip ratio indicates the degree of slippage of the roller. Next, we investigated the relation between the dynamic frictional characteristics generated during rolling and the slip ratio and found that the Slip-Stick phenomenon remarkably appeared at the test machine speed at which the vibration acceleration was maximum even when water was added. Also, a frequency analysis showed that when the vibration acceleration increased, the resonance frequency decreased, and the phenomenon of uniting was confirmed for all types of coal, suggesting that the abnormal vibration that occurred was self-excited vibration.
Design Methodology of a Toy to Improve Manual Abilities on Medicine Students
Authors: Vega Bello Jessica Daniela , Escalera Matamoros Yesica , Treviño Arizmendi Arturo , Haro Mendoza Daniel , Borja Vicente , Jiménez Corona José Luis
Published: February 2021

Theoretical knowledge is important in all disciplines, but practical knowledge is of utmost importance in many of them, such is the case in engineering, medicine, and architecture. In most of these majors’ instructors focus more on the theoretical area and set aside the practical one. That is why it is important to develop educational tools to improve students’ practice. Medical students at the Universidad Nacional Autónoma de México were our case of study since we noticed a lack of practical knowledge during their second year at University. In this paper, we present a design methodology of a toy for the students of medicine to exercise and improve their manual precise movements and motor sequencing skills, in order to improve their practical abilities by using it.

This methodology emphasizes the importance of specific movements that surgeons do while they perform basic surgical procedures, intending to imitate them when they use the toy. Therefore, procedures like cutting, suturing, exposure, among others were performed by a surgeon, recorded, and analyzed. As a result, it was observed that some movements were repeated in most of the procedures. Based on this, a device was designed so that the user may be able to repeat the movements following a series of audiovisual instructions as a game. To validate its efficiency manual precision tests were used to compare the individual students’ improvement before and after using it.

Once the device was built as a toy, 12 second-year medical students took the precision tests, the measured variable was the time they used to complete both tests. Furthermore, they practiced with the toy for 10 days, 6 minutes per day. On the last day, after using it, each student performed the precision tests once again to obtain a quantitative value of their improvement.

The time spent by each student to perform the first precision tests were compared to the last after using the toy. The results showed that the execution time was reduced by an average of 53.75 seconds in the first precision test and 45 seconds in the second. This indicates that the use of the toy allows students to improve their manual precision skills, affecting the execution time of tasks that require accurate manual precision. Also, it was observed that the methodology developed could be applied and extrapolated to other disciplines such as engineering, in order to develop similar toys or devices that could enhance manual skills.
A Blended System Dynamics-Discrete Event Physics-Based Model for Anomaly Detection in Cyber-Physical Manufacturing Systems
Authors: Yu Hong , Raghavan Ajay , Mostafavi Saman , Jung Deokwoo , Sasaki Yukinori , Ogura Tetsuyoshi , Minegishi Akira , Tajika Yosuke
Published: February 2021

Being able to quickly detect anomalies and reason about their root causes in critical manufacturing systems can significantly reduce the analysis time to bring operations back online, thus reducing expensive unplanned downtime. Machine learning-based anomaly detection approaches often need significant amounts of labeled data for training and are challenging to scale for manufacturing deployments. A robust blended system dynamics and discrete event simulation physics-based modeling methodology is proposed for the task of automated anomaly detection. The blended model consists of discrete event simulation (DES) components for the discrete manufacturing process modeling, and system dynamics (SD) components for continuous variables. The methodology strikes a balance between the computational overhead for online monitoring and the level of details required to perform anomaly detection tasks. The implementation of models takes an object-oriented approach, allowing multiple components of a smart factory to be robustly described in a modular, extendable and reconfigurable manner. The proposed methodology is applied to and validated by data collected from a real commercial manufacturing plant. A production line is modeled with DES components and heat transfer is modeled with SD. The blended model is then utilized for anomaly detection. It is demonstrated that the model-based approach is effective not only for detecting but also explaining particular types of anomalies in a commercial discrete manufacturing system.
A Mathematical Model to Assess Occupant Compartment Intrusion on Rear Occupant Responses in Rear Crashes
Authors: Stephens Gregory , Michalski David , Parenteau Chantal S. , Burnett Roger
Published: February 2021

Rear occupant protection in rear crashes is a complex issue. Structural intrusion has been shown to be a significant factor in the injury mechanism of second-row children. In this study, a new model was developed to help quantify dynamic second-row intrusion, in terms of displacement, velocity, and acceleration, and assess its effect on rear occupant responses as a function of time.

A mathematical model was developed using crash test data based on two reconstructed field accidents involving two different rear-ended vehicles with second-row children. The model also used the corresponding FMVSS 301R-type rear barrier tests of a similar vehicle.

The crash test pulse data and videos from FMVSS 301R-type tests were analyzed to determine the timing and magnitude of second-row intrusion. Crash tests that had been conducted to simulate the field accidents were then used to validate the model. These tests included instrumented ATDs (Anthropometric Test Device) seated in the second-row area of the struck vehicles. The biomechanical responses were used to assess the validity of the mathematical model.

Comparison between the mathematical model and the test data showed good agreement. For example, the model correctly showed that the dynamic second-row intrusion was greater than residual/static intrusion/displacement. The model also predicted accelerations that were in good agreement with the test data.

Video analysis and head/chest acceleration time histories of the ATD’s indicated that intrusion occurred early and was an important factor in the occupant responses. Both the extent and velocity of dynamic intrusion also influenced the biomechanical responses.

The model predicted head and chest accelerations that were greater than the overall vehicle accelerations due to localized structural intrusion.

The mathematical model developed in this study is a first to assess the dynamic effect of second-row intrusion on rear occupant responses. Identifying factors that influence injury mechanisms are important when assessing the potential effectiveness of countermeasures.
Study of Erosion and Accretion From Water and Steam Over Pipe Walls of Condenser in a Thermal Power Plant
Authors: Asok Eshwanth , Shah Karan Ashitbhai , Khan Jobaidur Rahman
Published: February 2021

It is extremely important and required by thermal power plant to condense the exhaust steam from steam turbine outlets to obtain maximum efficiency on varying loads. Surface type condensers are often used to meet these demands. By condensing the exhaust steam at a pressure below atmospheric pressure, the pressure drop between inlet and outlet of turbine is increased which increases the amount of heat available for conversion to mechanical energy by the turbine.

Increasing the heat transfer rate of condenser is an effective method to increase the overall efficiency of a thermal power plant. With condenser playing a vital role in overall plant efficiency, it is important to analyze the areas of fouling/erosion, which reduce the condensation rate. The condenser used in a company has been in operation for many years, so to study the effect of erosion on the condenser pipelines, a computational simulation of a section of the condenser in 210 MW thermal power plant with erosion modeling has been done using Fluent code.

To help understand the steam cooling in the condenser, current study analyses a 3D section of the condenser used in a 210 MW thermal power plant using a commercial ANSYS/FLUENT code. A boundary layer coupled mesh is used to simulate the interaction of steam and water with the condenser tubes. Models to simulate the flow of water inside the tubes and low-pressure steam over the tubes are incorporated to show the heat transfer between the steam and water domain through the pipe walls along with incorporation of accretion and erosion model, specially the erosion. Analysis of erosion accretion due to Calcium salts are taken in consideration to interpret the location, where scaling happens and how the yearlong scaling affects the heat transfer ability of the heat transfer tubes. There is one build-in erosion and accretion model in FLUENT, which accounts of erosion/accretion on a surface from solid particle. Although the water is liquid, but the article that is responsible for erosion and accretion is solid, e.g. Calcium salt. The result shows that the heat transfer rate is not constant along the tube over a period due to erosion and untreated hard water used for cooling purpose. The Erosion model predicts the most prominent erosion/accretion sites inside the tubes and stresses on the importance of treatment of the recirculating hard water. A liquid particle erosion can also be modeled in future if needed.
About the robustness of Schottky conjecture when quasi-one-dimensional stages are present
Authors: de Carvalho Neto Edgar Marcelino
Published: February 2021

The Schwarz–Christoffel transformation is used to analytically evaluate the field enhancement factor close to the apex of two-stage conducting structures consisting of a vertical line centered on the top of an isosceles trapezoidal protrusion on an infinite line. This way the validity of the Schottky conjecture (SC) is assessed for different ratios involving the dimensions of the system, which is expected to model quasi-one-dimensional structures, such as nanotubes, on the top of multistage structures used in different scientific and technological applications. The results obtained in this work suggest that the SC remains a good approximation beyond the region in which it is usually expected to be valid.
Particle-in-cell simulation of an industrial magnetron with electron population analysis
Authors: Yue Andong , Pearlman Marcus , Worthington Mike , Cipolla John , Browning Jim
Published: February 2021

Results from a particle-in-cell simulation study of L3Harris CWM-75 kW are presented; the continuous wave cooker magnetron typically operates at 18 kV, 5 A, 1900 G, 896–929 MHz. The startup process of the device has been simulated in 3D by using the PIC code VSim. The startup behavior was examined with (1) no priming, (2) RF priming, and (3) cathode modulation. Under no priming, the simulated device failed to oscillate in a simulation time of 1000 ns. Oscillations were achieved with both RF priming (150 ns) and cathode modulation (180 ns). Half (∼40 kW) of the device’s typical operating power at a frequency of 915 MHz, the device’s π-mode frequency, was used for the RF priming, and the priming was active only during the first 50 ns of the simulation. The device then oscillated later, but oscillation soon failed as the spokes collapsed. Continuous cathode modulation was also performed at 915 MHz with stable oscillation after 180 ns. A method for analyzing the electron device physics during the magnetron startup was developed by examining time-dependent particle distribution profiles in r and φ. These results provide insight into the conditions in the electron hub that lead to oscillation, particularly the azimuthal velocity distribution where the distribution shows a clear low or negative velocity prior to the start of oscillation.
Trunk Inclination During Squatting is a Better Predictor of the Knee-Extensor Moment Than Shank Inclination
Authors: Straub Rachel K. , Barrack Adam J. , Cannon Jordan , Powers Christopher M.
Published: February 2021

Context: A limitation of previous studies on squatting mechanics is that the influence of trunk and shank inclination on the knee-extensor moment (KEM) has been studied in isolation. Objective: The purpose of the current study was to determine the influence of segment orientation on the KEM during freestanding barbell squatting. Design: Repeated-measures cross sectional. Setting: University research laboratory. Participants: Sixteen healthy individuals (8 males and 8 females). Intervention: Each participant performed 8 squat conditions in which shank and trunk inclinations were manipulated. Main Outcome Measures: 3D kinematic and kinetic data were collected at 250 and 1500 Hz, respectively. Regression analysis was conducted to identify the individual relationships between the KEM and the trunk and shank inclination at 60° and 90° of knee flexion. To identify the best predictor(s) of the KEM, stepwise regression was implemented. Results: Increased shank inclination increased the KEM (P < .001, R2 = .21–.25). Conversely, increased trunk inclination decreased the KEM (P < .001, R2 = .49–.50). For the stepwise regression, trunk inclination entered first and explained the greatest variance in the KEM (all P < .001, R2 = .49–.50). Shank inclination entered second (all P < .010, R2 = .53–.54) and explained an additional 3% to 5% of the variance. Conclusions: Our results confirm that inclination of the trunk and shank have an opposing relationship with the KEM. Increased forward shank posture increases the KEM, while increased forward trunk posture decreases the KEM. However, when viewed in combination, the trunk was the superior predictor of the KEM, highlighting the fact that increased quadriceps demand created by a forward shank can be offset by trunk inclination.
A pebble accretion model for the formation of the terrestrial planets in the Solar System
Authors: Johansen Anders , Ronnet Thomas , Bizzarro Martin , Schiller Martin , Lambrechts Michiel , Nordlund Åke , Lammer Helmut
Published: February 2021

A new theory for formation of Earth by accretion of small pebbles explains how our planet acquired its water and carbon.
Microfluidic tumor-on-a-chip model to evaluate the role of tumor environmental stress on NK cell exhaustion
Authors: Ayuso Jose M. , Rehman Shujah , Virumbrales-Munoz Maria , McMinn Patrick H. , Geiger Peter , Fitzgerald Cate , Heaster Tiffany , Skala Melissa C. , Beebe David J.
Published: February 2021

Microfluidic platform reveals the effects of tumor environmental stress on natural killer cell biology.
Dislocation-mediated shear amorphization in boron carbide
Authors: Reddy Kolan Madhav , Guo Dezhou , Song Shuangxi , Cheng Chun , Han Jiuhui , Wang Xiaodong , An Qi , Chen Mingwei
Published: February 2021

A previously unidentified amorphization mechanism of boron carbide yields insights into the failure of superhard materials.
Polyamines drive myeloid cell survival by buffering intracellular pH to promote immunosuppression in glioblastoma
Authors: Miska Jason , Rashidi Aida , Lee-Chang Catalina , Gao Peng , Lopez-Rosas Aurora , Zhang Peng , Burga Rachel , Castro Brandyn , Xiao Ting , Han Yu , Hou David , Sampat Samay , Cordero Alex , Stoolman Joshua S. , Horbinski Craig M. , Burns Mark , Reshetnyak Yana K. , Chandel Navdeep S. , Lesniak Maciej S.
Published: February 2021

Glioma-associated myeloid cells generate polyamines to survive and function within the acidic tumor microenvironment.
Repression of Wnt/β-catenin signaling by SOX9 and Mastermind-like transcriptional coactivator 2
Authors: Sinha Abhishek , Fan Vinson B. , Ramakrishnan Aravinda-Bharathi , Engelhardt Nicole , Kennell Jennifer , Cadigan Ken M.
Published: February 2021

SOX9 inhibits Wnt signaling by promoting GSK3-independent turnover of β-catenin, via transcriptional activation of MAML2.
An engineered decoy receptor for SARS-CoV-2 broadly binds protein S sequence variants
Authors: Chan Kui K. , Tan Timothy J. C. , Narayanan Krishna K. , Procko Erik
Published: February 2021

An engineered decoy receptor tightly binds S from diverse SARS-related coronaviruses with limited potential for viral escape.
Electronics-free pneumatic circuits for controlling soft-legged robots
Authors: Drotman Dylan , Jadhav Saurabh , Sharp David , Chan Christian , Tolley Michael T.
Published: February 2021

Pneumatic circuits without electronic components enable automatic control of the walking gait of a soft-legged robot.
Electro-pneumatic pumps for soft robotics
Authors: Diteesawat R. S. , Helps T. , Taghavi M. , Rossiter J.
Published: February 2021

A lightweight, flexible, high-performance, electrically driven pump can replace large, heavy air supplies in soft robots.
APOE immunotherapy reduces cerebral amyloid angiopathy and amyloid plaques while improving cerebrovascular function
Authors: Xiong Monica , Jiang Hong , Serrano Javier Remolina , Gonzales Ernesto R. , Wang Chao , Gratuze Maud , Hoyle Rosa , Bien-Ly Nga , Silverman Adam P. , Sullivan Patrick M. , Watts Ryan J. , Ulrich Jason D. , Zipfel Gregory J. , Holtzman David M.
Published: February 2021

Targeting APOE using an anti-APOE antibody ameliorates amyloid pathology while protecting cerebrovascular integrity and function.