bluuebunny/crossref_metadata_2025 huggingface dataset:
New predictors to identify severe cases during intravenous immunoglobulin therapy in Kawasaki disease
Authors: Iwasa Mitsuji , Inukai Sachiko
Published: January 2022

Background

The purpose of this study was to predict which patients would require plasma exchange therapy (PEX) using laboratory findings during intravenous immunoglobulin (IVIG) therapy in Kawasaki disease.

Methods

A retrospective, single‐center, cohort study was conducted. Of the 621 IVIG‐treated patients, 166 patients who received a second IVIG dose on the second day after initiation of IVIG were included. The endpoint was PEX. Participants were divided into two groups: 10 patients who received PEX and 156 patients who did not. The variables were C‐reactive protein (CRP), white blood cell count (WBC), and neutrophil fraction (NEUT) at three time points: pre‐initial IVIG, pre‐second IVIG, and post‐second IVIG. The change ratio (post‐IVIG value/pre‐IVIG value) of each variable, with each IVIG dose, was calculated. Receiver operating characteristic analysis determined the area under the curve (AUC) and cut‐off values.

Results

The variables with an AUC > 0.9 were CRP (post‐second IVIG), change ratio of CRP (CRP value post‐second IVIG/CRP value pre‐second IVIG), NEUT (pre‐second IVIG), and NEUT (post‐second IVIG). Among these, the variables with high sensitivity were CRP (post‐second IVIG) and the change ratio of CRP (second IVIG), with cut‐off values of 9.52 mg/dL and 0.99, respectively. The sensitivity and specificity of these variables were 100% and 91%, and 100% and 80%, respectively. The combined sensitivity and specificity (95% confidence intervals) of these two variables were 100% (59–100) and 94% (89–97).

Conclusion

High CRP levels and the change ratio of CRP after the second IVIG dose were associated with PEX.
Atherosclerosis: Known and unknown
Authors: Fan Jianglin , Watanabe Teruo
Published: January 2022

Atherosclerotic disease, such as myocardial infarction and stroke, is the number one killer worldwide. Atherosclerosis is considered to be caused by multiple factors, including genetic and environmental factors. In humans, it takes several decades until the clinical complications develop. There are many known risk factors for atherosclerosis, including hypercholesterolemia, hypertension, diabetes and smoking, which are involved in the pathogenesis of atherosclerosis; however, it is generally believed that atherosclerosis is vascular chronic inflammation initiated by interactions of these risk factors and arterial wall cells. In the past 30 years, the molecular mechanisms underlying the pathogenesis of atherosclerosis have been investigated extensively using genetically modified animals, and lipid‐reducing drugs, such as statins, have been demonstrated as the most effective for the prevention and treatment of atherosclerosis. However, despite this progress, questions regarding the pathogenesis of atherosclerosis remain and there is a need to develop new animal models and novel therapeutics to treat patients who cannot be effectively treated by statins. In this review, we will focus on two topics of atherosclerosis, “pathology” and “pathogenesis,” and discuss unanswered questions.
Performance of diagnostic coding and laboratory testing results to measure COVID‐19 during pregnancy and associations with pregnancy outcomes
Authors: Regan Annette K. , Arah Onyebuchi A. , Sullivan Sheena G.
Published: January 2022

Background

Large‐scale evaluation of COVID‐19 is likely to rely on the quality of ICD coding. However, little is known about the validity of ICD‐coded COVID‐19 diagnoses.

Objectives

To evaluate the performance of diagnostic codes in detecting COVID‐19 during pregnancy.

Methods

We used data from a national cohort of 78,283 individuals with a pregnancy ending between 11 March 2020 and 31 January 2021 in the OptumLabs® Data Warehouse (OLDW). OLDW is a longitudinal, real‐world data asset with de‐identified administrative claims and electronic health record data. We identified all services with an ICD‐10‐CM diagnostic code of U07.1 and all laboratory claims records for COVID‐19 diagnostic testing. We compared ICD‐coded diagnoses to testing results to estimate positive and negative predictive values (PPV and NPV). To evaluate impact on risk estimation, we estimated risk of adverse pregnancy outcomes by source of exposure information.

Results

Of 78,283 pregnancies, 5644 had a laboratory test result for COVID‐19. Testing was most common among older individuals, Hispanic individuals, those with higher socioeconomic status and those with a diagnosed medical condition or pregnancy complication; 52% of COVID‐19 cases was identified through ICD‐coded diagnosis alone, 19% from laboratory test results alone and 29% from both sources. Agreement between ICD‐coded diagnosis and laboratory testing records was high 91% (95% confidence interval [CI] 90, 92). However, the PPV of ICD‐code diagnosis was low (36%; 95% CI 33, 39). We observed up to a 50% difference in risk estimates of adverse pregnancy outcomes when exposure was based on laboratory testing results or diagnostic coding alone.

Conclusions

More than one‐in‐five COVID‐19 cases would be missed by using ICD‐coded diagnoses alone to identify COVID‐19 during pregnancy. Epidemiological studies exclusively relying on diagnostic coding or laboratory testing results are likely to be affected by exposure misclassification. Research and surveillance should draw upon multiple sources of COVID‐19 diagnostic information.
Sublimation From Disks to Air Streams Flowing Normal to Their Surfaces
Authors: Sogin H. H.
Published: January 2022

Mass transfer by sublimation from 4-in-diam naphthalene disks to the stagnation regions of impinging jets of air was calibrated with heat transfer by convection in an identical configuration. Within the limits of the experimental reproducibility, all results were brought into a single correlation using Colburn’s formulation of the heat-mass analogy. The calibration was then employed to obtain mean coefficients of heat transfer on disks with free edges. This part of the investigation was performed using two sorts of air streams; namely, a 10-in-diam jet discharging freely into the atmosphere and a 5-ft-diam stream in a closed throat of a wind tunnel. The air speeds ranged from 22 to 293 fps, and the disks, made of naphthalene or of paradichlorobenzene, were 2.25 and 4 in. diam. The results of this part of the investigation may be represented by the equation j√(GDpμf)=1.08 with a probable error of ±3 per cent. Including Powell’s work on evaporation of water from disks, the equation covers a range of Reynolds number from 2000 to 600,000 with a maximum deviation of about ±10 per cent from the experimental points. The results of this work possibly may be of some general interest with regard to heat transfer at the stagnation region of a surface of revolution and perhaps may be of some use in dew point or water-content instrumentation.
Heat Transfer From a Rotating Cylinder With and Without Crossflow
Authors: Kays W. M. , Bjorklund I. S.
Published: January 2022

In this paper the problem of convection heat transfer from a rotating cylinder is extended to the case of a cross, or normal flow to the cylinder. Experimental heat-transfer data are presented for a cylinder rotating with and without crossflow. The data for the cylinder rotating with no crossflow are in substantial agreement with the results of previous work, and also with the results of a heat-and-momentum-transfer-analogy solution for convection with no crossflow. Measured temperature profiles in the boundary layer of the heated rotating cylinder are in very good agreement with the analogy solution, and indicate that the boundary layer on a rotating cylinder is quite similar to a turbulent boundary layer on a stationary surface out to about y+ = 20. Thereafter a secondary flow becomes the controlling mechanism. The experiments with combined rotation and crossflow indicate two flow regimes; the first for the cylinder peripheral velocity less than twice the crossflow velocity, in which the crossflow provides the controlling effects; the second for the cylinder peripheral velocity greater than twice the crossflow velocity, in which there is a continuous boundary layer around the cylinder and the rotational velocity provides the controlling effects on heat transfer. It is shown that the combined effects of rotation, free convection, and crossflow can be correlated by the equation NNu=0.135[(0.5NR2+NRs2+NGr)NPr]1/3 for the rotating Reynolds number in the range 2000 to 45,000.
Shear-Strain Rate in Metal Cutting and Its Effects on Shear-Flow Stress
Authors: Kececioglu Dimitri
Published: January 2022

A relationship is derived from which the average shear-strain rate in the shear zone, during orthogonal as well as oblique cutting, may be calculated if the average shear-zone thickness is known. A method of determining the average shear-zone thickness is described, which involves the use of a mechanism that stops the cutting process practically instantaneously and thus “freezes” the process of chip formation. The variation of the shear-zone thickness and of the shear-strain rate with the normal rake angle, the inclination angle, the feed, and the cutting speed when dry-machining SAE 1015, 118 Bhn seamless-steel tubing is determined. The average shear-zone thickness is found to vary from 0.0007 to 0.007 in. and the average shear-strain rate from 2500 to 212,000 per sec. The shear-flow stress in the shear zone is calculated and found to be 2⅓ to 3¼ times the static shear-flow stress of approximately 26,000 psi. The effect of the shear-strain rate on the shear-flow stress in the shear zone is analyzed and it is found that an increase in the shear-strain rate is accompanied by a significant increase in the shear-flow stress.
Analysis of Incompressible, Nonviscous Blade-to-Blade Flow in Rotating Blade Rows
Authors: Kramer J. J.
Published: January 2022

A method is developed for the blade-to-blade solution of the incompressible, nonviscous flow through rotating blade rows (including the inlet region) with or without splitter vanes. Splitter vanes are partial blades which do not extend to the inlet of the blade row. Numerical solutions are obtained for four weight flows through a centrifugal impeller without splitter vanes at one operating speed. The results are presented in a series of figures showing streamlines and relative velocity contours.
Two-Phase Flow in Rough Tubes
Authors: Chisholm D. , Laird A. D. K.
Published: January 2022

This paper presents data for pressure drop and saturation during flow of air-water mixtures in smooth and rough horizontal tubes. Improvements in the two-phase flow correlations for rough tubes are presented. Approximate empirical relationships developed using these improvements correlated the majority of the data within 15 per cent.
Transient Free Convection From a Vertical Flat Plate
Authors: Siegel Robert
Published: January 2022

The method of characteristics is employed to obtain solutions to the time dependent free-convection equations of momentum and energy placed in integral form (Karman-Pohlhausen method). Two boundary conditions are considered for a vertical flat plate of infinite width and semi-infinite length which is initially at ambient temperature in quiescent fluid: (a) The plate is suddenly raised to a uniform higher temperature, and (b) the plate suddenly begins to produce a uniform heat flux at its surface. The results yield the time required for steady flow to be established as a function of position along the plate. Heat-transfer coefficients are obtained for the initial stage of motion during which the convective process is one dimensional. The approximate velocity and temperature profiles obtained from the analysis are compared with more precise solutions of the differential equations for the initial stage of motion and for steady state.
Similar Solutions for Free Convection From a Nonisothermal Vertical Plate
Authors: Sparrow E. M. , Gregg J. L.
Published: January 2022

An analysis is made for laminar free convection from a vertical flat plate having a nonuniform surface temperature. The following two families of surface temperatures were studied: (i) Tw – T∞ = Nxn, (ii) Tw – T∞ = Memx. Both families submit to mathematical analysis by the conventional techniques of laminar boundary-layer theory; i.e., they permit the finding of similar solutions of the boundary-layer equations. Numerical solutions have been carried out for Pr = 0.7 and 1.0; i.e., for gases. Heat-transfer results are presented, as are temperature and velocity distributions.
A New Method of Heat-Exchanger Design With Specified Inlet and Outlet Conditions
Authors: Fairall R. S.
Published: January 2022

In order to solve the general design problem for a heat exchanger, the relative advantages of a number of possible solutions must be compared with the respective disadvantages. The solutions may be compared on a basis of flows, pressure losses, temperatures, and heat-exchanger size and weight. This paper develops a set of simultaneous equations which expresses the size of a heat exchanger as a function of the operating conditions and the surface temperatures within the unit and permits this comparison to be made on an analytical basis. The general case of counterflow, parallel flow, single-pass crossflow, and two-pass crossflow are solved; examples and figures are included.
Development of Ceramic Insulating Materials for High-Temperature Use
Authors: Kingery W. D. , Klein J. D. , McQuarrie M. C.
Published: January 2022

Factors affecting the thermal conductivity of ceramics in the temperature range from 2200–4000 F are considered from the point of view of high-temperature insulation. The effective conductivity of solids and pores over a wide range of temperatures is analyzed. Particular attention is devoted to the effects of structure and phase distribution. This analysis is related to the development of optimum properties in thermal insulation for the temperature range considered.
Bubble Growth Rates in Boiling
Authors: Griffith Peter
Published: January 2022

The conditions determining the growth rate of a bubble on a surface in boiling are considered and a mathematical model framed in the light of these conditions. The growth rate is then calculated for bubbles growing under a range of conditions of pressure, wall superheat, and bulk fluid temperature. The average growth rate of a bubble is found to decrease with increasing maximum size and to decrease with increasing pressure. At high pressure, the maximum size of the bubble is found to be independent of pressure and primarily a function of the thickness of the superheated layer near the surface.
Heat Transfer to Supercritical Water
Authors: Dickinson N. L. , Welch C. P.
Published: January 2022

Heat-transfer coefficients for supercritical water are presented for flow in an electrically heated AISI Type 304 stainless-steel tube having an inside diameter of 0.300 in. Bulk fluid temperatures were varied from 220 to 1000 F at 4500 psi, and over a more limited temperature range at 3500 psi. Mass flows tested include 1.6 to 2.5 × 106 lb/hr-sq ft, and a flux range of 280,000 to 580,000 Btu/hr-sq ft was covered. Values of film conductance in the vapor region were found to be substantially higher than those predicted by extrapolation of data found in the literature, or by recent formulas based on a theoretical approach. These findings are of special interest to the boiler industry which is presently designing units for use at supercritical conditions.
Transition from Laminar to Turbulent Shear Flow—A Review of Some Recent Advances in Its Understanding
Authors: Morkovin M. V.
Published: January 2022

Recent experimental studies of transition from laminar to turbulent shear flows are reviewed. Certain common features are emphasized and related to the stability theories of viscous shear layers. The three-dimensional character, the unsteadiness, and the nonlinear and random behavior of the latter stages of the transition process are also examined.
Effect of Temperature Variation on Composition, Fouling Tendency, and Corrosiveness of Combustion Gas from a Pulverized-Fuel-Fired Steam Generator
Authors: Piper John D. , Van Vliet Hazen
Published: January 2022

Metal condensers, cooled to selected temperatures between 87 and 242 F, were placed in stack gas of a pulverized-fuel-fired steam generator. The amount and nature of substances depositing upon the condensers were determined as well as the corrosion resistances of many materials. Chlorides were found to deposit at unsuspectedly high temperatures and concentrations. Corrosion rates increased markedly as the water dew point was reached.
Liquid-Flowmeter Calibration Techniques
Authors: Shafer M. R. , Ruegg F. W.
Published: January 2022

Calibration techniques for liquid flowmeters are discussed with emphasis on problems which are known to influence the accuracy of calibration procedures. Also, reference methods which have been used to evaluate the comparative accuracy of different calibrators are described. The results of comparative accuracy tests on four calibrators of different designs are presented and it is shown that the agreement between these is within ±0.15 per cent in the test range of 10,000 to 100,000 lb per hr. The many precautions necessary to approach this precision from the traditionally accepted “plus and minus one per cent” are given in detail.
Transient Temperature and Thermal Stresses in Skin of Hypersonic Vehicle With Variable Boundary Conditions
Authors: Chen Shih-Yuan
Published: January 2022

The transient temperature distribution and thermal stresses resulting from aerodynamic heating in the skin of a vehicle at hypersonic speeds are found analytically for a finite slab in which one boundary has a variable coefficient of heat transfer and a variable adiabatic wall temperature while the other boundary is insulated. The purpose of this paper is to introduce the concept of using exponential functions of time to represent the coefficient of heat transfer and the adiabatic wall temperature. In general, one can choose as many exponential functions as necessary to obtain a better solution since the solution is a straightforward mathematical problem. This paper has considered the sum of two exponential functions and a constant for the coefficient of heat transfer and the sum of two exponential functions and a constant for the adiabatic wall temperature. This represents several types of aerodynamic heating problems. Solutions for three special cases are given to show that the general solution also can be applied to simpler problems.
Research on Dynamic Movement of Temperature and Pressure During Hydrate Depressurization Mining
Authors: Deng Song , Wang Hao , Wang Caibao , Ma Mingyu , Wei Yaohui , Liu Yuan
Published: January 2022

It is of great significance to study the dynamic movement of temperature and pressure during depressurization mining process of hydrate reservoir. This paper first obtains the formula for calculating the temperature and pressure of hydrate decomposition based on the law of conservation of mass, conservation of energy, and phase equilibrium, Hydrateressim (HRS) is used to carry out the numerical simulation of the front edge of the one-dimensional model. The results show the pressure and the hydrate saturation front are correlated with the temperature front edge and compared with the Computer Modelling Group Ltd. (CMG) simulation results. It is found that the pressure front edge is an area in the balance model and an interface in the dynamic model. Then the movement of the front edge of the three-dimensional model was simulated. By simulating the movement regulation of pressure, temperature, and hydrate saturation front of each layer at different times, the longitudinal decrease of each layer is compared and analyzed. The conclusion drawn is that the bottom-hole pressure of the production well is an important factor for production, and the endothermic reaction of hydrate will cause the dynamic movement of temperature to lag slightly behind the pressure and hydrate saturation. By determining the relationship between the pressure and the temperature front, the position of the front edge of the hydrate saturation can be inferred that it is the position of the decomposition front and it overcomes the limitation of the experimental method that the hydrate saturation cannot be measured.
Multi-Degree-of-Freedom Modeling for Electric Powertrains: Inertia Effect of Engine Mounting System
Authors: Kaul Sudhir
Published: January 2022

It has been widely acknowledged over the last couple of decades that the vibroacoustic characteristics of electric powertrains assembled to engine mounting systems are significantly different from internal combustion engines. These distinctions necessitate the modeling of inertial properties of the mounting system in order to account for internal resonances and wave effects. This paper presents a spatial model with three degrees-of-freedom that can be used to capture internal resonances of the engine mount system at frequencies well above 1 kHz. Such a model could significantly enhance the understanding of the vibroacoustic performance of the system while being specifically beneficial for electric powertrains. Results indicate that the model is successful in capturing internal resonances up to 10 kHz while also representing the lower order eigenmodes of the powertrain. The iterative capability of the model renders it specifically beneficial for experimental characterization and model correlation. It is observed that force transmissibility is highly sensitive to the design parameters that govern the effective stiffness of the engine mounts. The model presented in this paper can be used for the optimization of engine mount systems for electric powertrains.
Improvement of Tolerance Simulation Model in Body in White Product Realization Loop by Integrating Manufacturing Joining Simulation
Authors: Zheng Hanchen , Litwa Frank , Paetzold Kristin
Published: January 2022

Tolerance simulation has already been applied throughout the product realization loop in automotive industry to improve the product quality while reducing the product cost. However, the capability of tolerance simulation is limited by the prediction accuracy. Although tolerance simulation methods for non-rigid part are available which involve the elastic deformation during the manufacturing process, there are still difficulties while addressing large deformations and the Body In White (BIW) joining processes, which have non-linear effects. Thus, the Finite Element Method (FEM) based joining simulation raises its importance as it simulates the physical properties of parts in system and helps to digitize the manufacturing process. A proper combination of the manufacturing process simulation with the tolerance analysis contributes to the product and process optimization.

In this paper, the current statistical tolerance simulation method is improved by integrating manufacturing joining simulations. The application of the joining-simulation based tolerance analysis is illustrated with an example of a sheet metal assembly in different product development phases. As a result, The critical tolerances are identified in the digital concept phase. The initial specified part tolerances are optimized regarding the assembly deviation requirements on the product characteristics and a given scrap rate. It contributes to reduce the production cost in the prototype phase, where the stamping machines are designed. Besides, the influence of tolerance change on the assembly dimensional quality in the late production phase is evaluated.
New Analytical Solutions for Orthotropic Rectangular Clamped Plates Under Pressure Loading
Authors: Rossi John , Weckner Olaf
Published: January 2022

The exact solution of a clamped rectangular orthotropic plate with pressure loading is presented. Unlike isotropic materials which behave equally in all directions, composites are strongly orthotropic due to the presence of stiff fibers in a relatively soft matrix. Similarly, metals with a definitive grain direction also exhibit a pronounced orthotropic behavior. The presence of aircraft cabin pressure induces bending of orthotropic panels used for example on doors and pressure bulkheads. Therefor the analysis of orthotropic rectangular clamped plates under pressure loading is needed in the sizing of modern aircraft structures.

Existing methods for calculating the bending deformation of a clamped rectangular plate are commonly based on the Rayleigh-Ritz method, or Finite Element Analysis, which are approximate methods. In contrast the solutions presented in this paper exactly satisfy the resulting governing differential equation. The solution procedure presented in this paper is an expansion of Timoshenko’s[1][2] superposition method to orthotropic materials. This solutions method leads to more accurate results particularly for the stresses and strains. The solution procedure is presented in this paper, along with the resulting final equations. Additionally we present comparisons of a convergence study comparing to other commonly used approximate analysis methods.
Entropy Generation Minimization to Optimize Heat Transfer in CSP Technologies Using Molten Salt System NaCl/KCl/MgCl2 as Heat Transfer Fluids
Authors: Haddad Fouad , Li Peiwen
Published: January 2022

In order to optimize the flow and heat transfer of solar collectors and heat exchangers that use molten salts NaCl-KCl-MgCl2 or KCl-MgCl2, entropy generation minimization principle is used as the criterion. Gnielinski correlation and Dittus-Bölter correlation for Nusselt number versus Reynolds number as well as Moody friction factor given by Petukhov were used for the calculation of heat transfer coefficient and pressure loss due to friction. The objective function, the entropy production of the heat transfer system, was expressed as the function of Reynolds number, Prandtl number, heating flux, pipe diameter, etc. The minimum entropy production could be found from the first order deviation of the entropy production versus Reynolds number. As a result of the analysis, the optimum Reynolds number was determined and thereby determined the optimum Nusselt number, convective heat transfer coefficient, friction factor, and tube diameter, which helps the selection of optimum flow velocities and diameter of fluid pipes. The analysis was conducted in the fluid temperature range of 550 °C to 700 °C which covers the operation temperature for supercritical CO2 cycles. Results from using different heat transfer correlations (Gnielinski correlation and Dittus-Bölter correlation) have been compared and some obvious deviations were identified. It indicates that the selection of heat transfer correlations can cause some deviation of the optimal parameters of Reynolds number and pipe diameter. From the researcher’s experience and experimental studies to molten chloride salts heat transfer, Gnielinski correlation for heat transfer is favorably recommended.
X-Ray Computed Tomography (XCT) Scanning Parameters Effects on the Hounsfield Unit (HU) Measurements for AA2011
Authors: Baydoun Ahmad M. R. , Hamade Ramsey F.
Published: January 2022

X-ray computed tomography (XCT) is a powerful technique that can detect internal defects and differentiate between different materials making XCT a valuable non-destructive evaluation (NDE). However, when X-ray CT is employed as an NDE method, the scanning parameters and methodology are often underreported leading to a lack of consensus on the optimal scanning parameters to use when analyzing a particular metal or alloy.

In this study, 16-bit X-ray CT scans are employed to characterize AA2011. Four parameters are investigated: scan (voxel) resolution, tube voltage, tube current, and sample size (thickness). Two sample disks are scanned simultaneously at an image bit depth of 16-bit. Mean and standard deviation Hounsfield Unit (HU) values are calculated which are then used to develop a predictive model for these two values. The model equation is used to produce surface plots to determine desired scanning parameters combination for characterizing AA2011 HU mean and standard deviation values. It is concluded that higher scanning resolution (smaller voxel), larger tube voltage and tube current settings, and thicker samples result in smaller of standard deviation HU values and converged mean HU values when scanning AA2011.
Nonlinear Dynamics Investigation of Bending Deflection Of Stiffened Composite Laminated Plate Using Lyapunov Exponent Conception
Authors: Yousuf Louay S.
Published: January 2022

In this paper, the nonlinear dynamics behavior of the bending deflection of stiffened composite laminated plate is investigated using largest Lyapunov exponent parameter. Wolf algorithm is used to quantify largest Lyapunov exponent in the presence of aspect ratios and fiber volume fractions. A power spectrum analysis has been added using the amplitude of Fast Fourier Transform (FFT) to detect the non-periodic motion of the stiffened plate. Numerical simulation is carried out using ANSYS software. The combined loading are the in-plane compression (uniaxial) mechanical load and shear force. The experiment setup has been done using buckling test machine whereas the upper head is moved downwards by servo hydraulic cylinder. The nonlinear dynamics behavior is increased with the increasing of aspect ratios and fiber volume fractions. The nonlinear dynamics behavior of stiffened composite laminated plate is decreased with the increasing of number of stiffeners.
Driving System Design and Control of Tick Collection Robot
Authors: Qiu Yesiliang , Dong Janet , Harrison Moretto Caroline “Niki”
Published: January 2022

This paper discusses the design and control of the driving system of a modern mobile robot which is used for a variety of rough terrains in remote areas to catch ticks. The autonomous robot offers a new solution to the collection of insects employing a mobile robot equipped with a vision system, GPS, and tick collection attachment. The new collection method is designed for US Army medical researchers and other biologists. The method would alter the way the technology gathers insects instead of human manual labor. The robot is designed to work on diverse terrains, such as soft turf, gravel, wet soil, and rocky soil.

A robotic solution to tick collection protects humans from a potential illness from bugs and insects, which may carry disease pathogens, injury from traveling across rough ground, and harm due to exposure to the elements. The robotic solution has the potential to apply to other research areas as well.

This paper will address the driving system design and control, including motor selection, determining the wheels, power requirements calculation, battery selection, discussion of control methods and diagrams, the coding logics based on ROS, and simulation of the robot in different settings and terrains. The future work is also described at the end of the paper.
Experimental and Computational Investigations of Spark Ignition Engine Performance
Authors: Venkateswaran Prabhakar
Published: January 2022

This paper describes a comprehensive experimental and numerical project implemented in a third-year applied thermodynamics course. In the project, students experimentally investigate the performance of a single-cylinder spark ignition (SI) and then develop a numerical model for the same engine which accounts for non-isentropic and finite-duration heat release effects. Using the experimental data and numerical model, students investigate the impact of compression ratio and spark timing on a variety of engine performance parameters such as peak pressure, power, and efficiency.

The project has some unique learning outcomes. First, students are able to compare the performance of a real SI engine to the Otto cycle model studied in class. Second, they gain experience applying concepts from thermodynamics, heat transfer and numerical methods to develop a realistic numerical model for the actual engine. In the development of the model, the constants needed for closure of the model and system of equations must be obtained empirically from the experimental data. This experience provides students with valuable insight into the inner workings of commercial simulation software packages where closure models are often developed from experimental data.

The paper concludes with suggestions of additional tasks and refinements that can be incorporated into this project to capture real-world effects such as heat losses during the combustion process. In addition, challenges in the implementation of this project and hurdles encountered by students are also discussed along with some suggestions to counter these issues.
Preliminary Study: Development of Sport Climbing Hold Measurement System for Performance Analysis
Authors: Pernus Nina , Munro Deborah
Published: January 2022

Sport climbing performance analysis requires knowledge of the specific motions and the interactions of the athlete with the climbing holds. The objective of this research is to develop a low-cost measurement system for detecting performance parameters with an instrument mounting screw used with a climbing hold. In the preliminary study, strain gauges were bonded to the shank of a screw and analyzed according to bending theory. For the experimental results, a climbing hold was mounted to a provisional wall with an instrumented mounting screw. The system was able to detect loads at increments of 2 kg applied to the climbing hold with accuracy and repeatability. Testing of loading when applied laterally from the center of the climbing hold showed that the alignment of the strain gauge and location of applied loads are important. The measurement system was capable of identifying the total contact time and time for each application of loads more than 1 kg. Results showed an instrumented mounting screw can be used for monitoring the climber’s fluency during climbing and provide information about load distribution between climbing holds during their ascent.
Concurrent Passive Broadband Vibration Suppression and Energy Harvesting Using a Dual-Purpose Magnetoelastic Metamaterial Structure: Experimental Validation and Modeling
Authors: Anigbogu Winner , Bardaweel Hamzeh
Published: January 2022

A dual-purpose metamaterial structure that can concurrently suppress vibrations and scavenge energy is presented. The metamaterial assembly presented in this work uses a permanent magnet-coil system in addition to an elastic cantilever beam to perform its dual functions. A prototype is manufactured and a COMSOL model is developed. Two bandgaps are observed at 205–257 Hz and 587–639 Hz. COMSOL simulations show excellent agreement with measured data. Within these bandgaps the structure blocks vibrations from traveling through and, simultaneously, converts vibrations into electric power. The first bandgap has a vibration attenuation level larger than the attenuation level observed in the second bandgap. Mode shapes reveal that the local resonators experience larger deformations in the first bandgap than in the second bandgap and the vibrational energy is mostly contained within the first bandgap where the resonant frequency occurs, i.e., 224 Hz. The ability of the metamaterial assembly to scavenge these vibrations while simultaneously suppressing them is demonstrated. At an optimum load resistance of 15 Ω, within the first bandgap, approximately 2.5 μW was generated, while 0.6 nW was measured within the second bandgap. At optimum load resistance, measurements show maximum electric power reaching 5.2 μW within the first bandgap.
Initial Development of Low-Cost Autonomous Rover for Pursuit of Moving Targets
Authors: James Cole , Matveev Konstantin I.
Published: January 2022

Technical progress in the development of autonomous off-road ground vehicles has recently led to the appearance of commercially available compact unmanned rovers. However, most of them remain rather costly. In the present study, an effort is made to develop a low-cost small-scale rover that can be used to pursue moving targets and perform other tasks, as well as be applicable as an educational platform for robotics courses. This paper presents the hardware/software implementation, including Arduino-compatible electronics architecture, GPS-RTK modules, enhanced compass, telemetry modules, and data logging. The vehicle control modes, communication with a moving target, adaptation of software libraries, and recommendations for sensing and steering are described. Three outdoor tests conducted with the autonomous rover are presented in the paper, including trajectory plots and time-dependent kinematic characteristics. In the first trial, the rover successfully reached a set of pre-programmed stationary waypoints. In the second test, the rover autonomously pursued a moving target that had a complicated trajectory. The rover was able to approach and follow the target, while larger deviations of relative distances between the rover and the target and bigger fluctuations of the rover speed were noticed during sudden turns and stops of the target. The last test was carried out with a sonar that can detect obstacles on the rover path, adding a capability for the rover to avoid collisions. The future development steps will include implementation computer vision modules, so more sophisticated autonomous control methods can be tested and optimized on this platform. The reported in this paper information will be useful for researchers, engineers and educators interested in constructing and using low-cost mobile platforms that can be instrumented with a number of sensors and perform a variety of tasks.
Increased Strength of 3D Printed Parts With Z-Pin Approach
Authors: Clemon Lee , Christopher Karan
Published: January 2022

Current extrusion-based 3D printing technologies adopt a layer-by-layer material deposition approach which is equivalent to stacking layers of material. This traditional 2.5D deposition plan is limited to depositing discrete, cross-sectional layers of the model. Such stacked layers are well known to induce anisotropic material behavior subject to part orientation during fabrication. Parts are loaded in their build direction (perpendicularly to layers), have up to a 50% decrease in tensile strength, and a significant 95% decrease in toughness when compared to x-y plane loading. In this work, we adopt a z-pinning approach inspired by traditional composite manufacturing methods to create cross-layer pins for part reinforcement. Our z-pins aim to reinforce the weaker interfaces between 3D printed layers, by facilitating stronger layer adhesion and by obstructing crack propagation through the planar structure of traditional 3D prints. This adaptation of the pin reinforcement concept for 3D printing is implemented on a consumer-grade Fused Filament Fabrication machine without the need for additional hardware. The fabrication machine is a standard linear 3-axis gantry design with off-the-shelf components. We create a custom workflow for editing the part mesh and toolpath plan that is inserted in the workflow between open-source slicing of the part file and part fabrication by the machine. This reads and edits the g-code instructions to insert the z-pin reinforcements into the existing deposition plan. A total of thirty-six tensile and flexural test specimens were fabricated using Polylactic Acid filament (PLA). The depth of the reinforcement pins, pin spacing, infill percentage, and the orientation of the build are perturbed to evaluate the effectiveness of the method. Tests were conducted on a calibrated Instron ElectroPuls E10000 using standard rectilinear test sample geometries. Test results show pinned tensile components exhibited up to a 25% increase in failure stress and a 300% increase in toughness when compared to the non-pinned control samples for the traditionally weak direction. Flexural strength was not significantly altered on a per-mass normalised comparison. The increase in strength is attributed to increased bonding across layers due to the added pins and abatement of delamination cracks propagating along layer boundaries. Abatement of delamination as a failure mode changes the material rupture mode to more of a desired ductile fracture of the polymer at the z-pin sites and delamination elsewhere in the plane. The results of this work provide a pathway to optimisation of material extrusion properties for anisotropic and isotropic designs by adjusting the quantity and location of z-pin reinforcements.
A Finite Element Based Method to Predict and Tailor the Energy Associated With Snap-Through Buckling of a Curved Beam
Authors: Florio Catherine S.
Published: January 2022

Although structural instabilities have traditionally been avoided in design as undesirable causes of failure, the rapid and potentially significant energy changes that result from the large displacements induced by buckling have gained recent interest as a favorable design feature for systems whose intent is energy dissipation or energy storage. Computational methods to quantify the energy changes associated with buckling of a transversely loaded curved beam are developed in this work. The methods are then used to predict the occurrence of buckling based on initial geometry and input load. The influence of the parameters of the numerical approximation, such as mesh and time step, is also explored. Correlations are made between the simpler behavior of a truss structure and the more complex behavior of a curved beam so that analytical solutions may be used to guide the understanding of structures whose response can only be predicted computationally. The techniques which are presented can aid in the more efficient design of energy dissipation, transfer, and storage systems that take advantage of buckling instability phenomena.
Compressive Stress Relaxation (CSR) Testing of Elastomers
Authors: Menon Dilip , Michael Robert J. , Gee David
Published: January 2022

This paper presents Compressive Stress Relaxation (CSR) results for various elastomer samples to ascertain their performance in sealing applications. The paper presents results of percent retained sealing force (%RSF) behavior and its relationship with compression set and hardness. Materials studied are used in critical piping and medical seal applications. CSR methodology is used to benchmark various materials in terms of sealing performance. Potential problems with the current standard of testing have also been identified that can affect the resolution and variability of the test. The paper details all the steps involved to perform accurate CSR testing and discusses advantages and disadvantages CSR testing might have over conventional tests used to verify seal performance such as compression set. This is only an introductory study and requires further tests with the same elastomers subjected to other process conditions, such as heat aging are also studied to understand how they affect %RSF. This can also be expanded to other materials to build a database of standard %RSF behavior under identical conditions.
Introducing Mechanical Engineering Students to Online Robotics Laboratories
Authors: Danesi Ruiz Juliana , Deierling Phillip E.
Published: January 2022

Due to Covid-19, in-person robotics labs held in previous semesters were not possible. This paper explores a well-established method to give the students an exceptional learning experience in a robotics class. By surveying students, data was gathered to account for students’ perception when designing the laboratories and lab manuals. In addition, to find an adequate program for the labs, different software was researched and tested. The main factors used to select a software were intuitiveness, cost, online resources, operating system compatibility, Python programming, and software usage. It is concluded that the RoboDK software is the most suitable software for the laboratories, and updated manuals needed to be designed for the Spring 2021 class. Last semester, Spring 2021, another survey was conducted to get students’ feedback on the new lab system. With the additional data, further research may be conducted to refine the laboratories’ assignments and manuals. This paper’s main contribution is to use and analyze RoboDK for online robotics laboratories. Therefore, through this research, a new method was presented that gave students hands-on experience on online laboratories.
On Periodic Firing Activities of a Hindmarsh-Rose Neuron Model With External Periodic Stimulus
Authors: Xu Yeyin , Feng Peihua
Published: January 2022

In the paper, periodic firing phenomenon of a Hindmarsh-Rose neuron model is explored by the discrete mapping method. The continuous nonlinear differential equations are discretized to form implicit mappings for periodic firing motions of neurons. Periodic firing and period doubling firing activities are investigated by changing the external excitation frequency. The influence of bifurcations on the periodic firing patterns is discussed. Time series membrane potential and adaptive current of such a modified Hindmarsh-Rose neuron model are presented. Fast-varying spikes and slow-varying zones of the neuron firing waves are revealed for a better understanding of the neural firing phenomenon. The nonlinear complexity of the periodic excited Hindmarsh-Rose neuron model is released.
Effects of Convection on Experimental Investigation of Heat Generation During Plastic Deformation
Authors: Hodges Wyatt , Phinney Leslie M. , Lester Brian , Talamini Brandon , Jones Amanda
Published: January 2022

In order to predict material failure accurately, it is critical to have knowledge of deformation physics. Uniquely challenging is determination of the conversion coefficient of plastic work into thermal energy. Here, we examine the heat transfer problem associated with the experimental determination of β in copper and stainless steel. A numerical model of the tensile test sample is used to estimate temperature rises across the mechanical test sample at a variety of convection coefficients, as well as to estimate heat losses to the chamber by conduction and convection. This analysis is performed for stainless steel and copper at multiple environmental conditions. These results are used to examine the relative importance of convection and conduction as heat transfer pathways. The model is additionally used to perform sensitivity analysis on the parameters that will ultimately determine β. These results underscore the importance of accurate determination of convection coefficients and will be used to inform future design of samples and experiments. Finally, an estimation of convection coefficient for an example mechanical test chamber is detailed as a point of reference for the modeling results.
Creep-Fatigue Damage of Heat-Resistant Alloys Caused by the Local Lattice Mismatch-Induced Acceleration of the Generation and Accumulation of Dislocations and Vacancies
Authors: Luo Yifan , Tezuka Shogo , Nakayama Koki , Nakayama Ayumi , Suzuki Ken , Miura Hideo
Published: January 2022

Degradation mechanism of the strength of a grain boundary in Ni-base superalloy under creep-fatigue loading at elevated temperature was investigated by using the modified Arrhenius equation, which explained the stress-induced acceleration of the local generation and diffusion of dislocations and vacancies. EBSD analysis confirmed that dislocations and vacancies started to generate and accumulate around grain boundaries and the interface between precipitates and matrix in grains. The generation and accumulation were accelerated around the interfaces with large difference in the lattice constant between the nearby crystallographic phases and grains. The activation energies of the diffusion of dislocations and vacancies measured under the harsh condition was much lower than those measured under the thermodynamically stable conditions. It was confirmed that there are two main acceleration mechanisms of the degradation of the crystallinity and strength of grain boundaries under a tensile stress at elevated temperatures: the acceleration of the generation and diffusion of dislocations and the acceleration of accumulation of voids due to the outward diffusion of component atoms from the grain boundaries. These phenomena were explained by the modified Arrhenius equations in which the effective activation energies were changed by the summation of the applied nominal stress and the localized internal stress around various interfaces quantitatively.