bluuebunny/crossref_metadata_2025 huggingface dataset:
A health systems intervention to strengthen the integration of tuberculosis and COVID‐19 detection: Outcomes of a quasi‐experimental study in a high burden tuberculosis district in KwaZulu Natal, South Africa
Authors: Curran Robyn , Murdoch Jamie , van Rensburg André J. , Bachmann Max , Awotiwon Ajibola , Ras Christy‐Joy , Petersen Inge , Prince Martin , Moultrie Harry , Nzuza Mercury , Fairall Lara
Published: February 2023

Objectives

The adverse effects of the COVID‐19 pandemic on tuberculosis (TB) detection have been well documented. Despite shared symptoms, guidance for integrated screening for TBand COVID‐19 are limited, and opportunities for health systems strengthening curtailed by lockdowns. We partnered with a high TB burden district in KwaZulu‐Natal, South Africa, to co‐develop an integrated approach to assessing COVID‐19 and TB, delivered using online learning and quality improvement, and evaluated its performance on TB testing and detection.

Methods

We conducted a mixed methods study incorporating a quasi‐experimental design and process evaluation in 10 intervention and 18 control clinics. Nurses in all 28 clinics were all provided access to a four‐session online course to integrate TB and COVID‐19 screening and testing, which was augmented with some webinar and in‐person support at the 10 intervention clinics. We estimated the effects of exposure to this additional support using interrupted time series Poisson regression mixed models. Process evaluation data comprised interviews before and after the intervention. Thematic coding was employed to provide explanations for effects of the intervention.

Results

Clinic‐level support at intervention clinics was associated with a markedly higher uptake (177 nurses from 10 intervention clinics vs. 19 from 18 control clinics). Lack of familiarity with online learning, and a preference for group learning hindered the transition from face‐to‐face to online learning. Even so, any exposure to training was initially associated with higher rates of GeneXpert testing (adjusted incidence ratio [IRR] 1.11, 95% confidence interval 1.07–1.15) and higher positive TB diagnosis (IRR 1.38, 1.11–1.71).

Conclusions

These results add to the knowledge base regarding the effectiveness of interventions to strengthen TB case detection during the COVID‐19 pandemic. The findings support the feasibility of a shift to online learning approaches in low‐resource settings with appropriate support and suggest that even low‐intensity interventions are capable of activating nurses to integrate existing disease control priorities during pandemic conditions.
RUVBL proteins are involved in plant gametophyte development
Authors: Dvořák Tomaštíková Eva , Yang Fen , Mlynárová Kristína , Hafidh Said , Schořová Šárka , Kusová Alžbeta , Pernisová Markéta , Přerovská Tereza , Klodová Božena , Honys David , Fajkus Jiří , Pecinka Ales , Schrumpfová Petra Procházková
Published: February 2023

The proper development of male and female gametophytes is critical for successful sexual reproduction and requires a carefully regulated series of events orchestrated by a suite of various proteins. RUVBL1 and RUVBL2, plant orthologues of human Pontin and Reptin, respectively, belong to the evolutionarily highly conserved AAA+ family linked to a wide range of cellular processes. Previously, we found that RUVBL1 and RUVBL2A mutations are homozygous lethal in Arabidopsis. Here, we report that RUVBL1 and RUVBL2A play roles in reproductive development. We show that mutant plants produce embryo sacs with an abnormal structure or with various numbers of nuclei. Although pollen grains of heterozygous mutant plants exhibit reduced viability and reduced pollen tube growth in vitro, some of the ruvbl pollen tubes are capable of targeting ovules in vivo. Similarly, some ruvbl ovules retain the ability to attract wild‐type pollen tubes but fail to develop further. The activity of the RUVBL1 and RUVBL2A promoters was observed in the embryo sac, pollen grains, and tapetum cells and, for RUVBL2A, also in developing ovules. In summary, we show that the RUVBL proteins are essential for the proper development of both male and particularly female gametophytes in Arabidopsis.
CT features of rounded atelectasis in chronic inflammatory pleural effusions in cats and dogs
Authors: Tran Danielle T. H. , Donovan Taryn A. , Daverio Heather , Le Roux Alexandre B.
Published: February 2023

Rounded atelectasis is well described in human medicine as focal lung deformation and collapse secondary to inflammatory pleural effusions and pleuritis. Specific CT features (round to ovoid soft tissue pulmonary attenuations, creation of an acute angle with the adjoining visceral pleura, and the presence of perinodular comet tail signs) support the diagnosis of rounded atelectasis in humans so that further diagnostic workup is not necessary in defining the nodules. In this retrospective case series, we described the CT characteristics of rounded atelectasis in eight cats and three dogs diagnosed with restrictive pleuritis secondary to either a chylothorax or pyothorax. Thirty‐six soft tissue attenuating pulmonary nodular lesions were identified on CT. Comet tail signs, consisting of bundles of bronchi and vessels coalescing into the pulmonary nodules, were associated with 92% of the nodules (33/36), and 92% of the nodules abutted and created an acute angle with the pleura (33/36). Other prevalent features included location in gravity‐dependent regions of the lung lobes (33/36, 92%), blurred hilar margins with sharper pleural margins of the nodules (33/36, 92%), presence of air bronchograms (30/36, 83%), homogeneous contrast‐enhancement (23/36, 64%), and volume loss of the affected lung lobe (22/36, 61%). Pulmonary malignant neoplasms were not found cytologically (6/11 patients) or histologically (5/11 patients). To avoid a misdiagnosis of neoplasia, veterinary radiologists should be aware of the CT features of rounded atelectasis and consider it as a differential for pulmonary nodular lesions in patients with concurrent inflammatory pleural effusion and pleuritis.
Teoría extendida de la conducta planificada aplicada al comportamiento de higiene oral en universitarios peruanos
Authors: Palomino Cordova Rene , Colqui Loyola Orfa Ruth , Leal Zavala Rafael Antonio , Buunk-Werkhoven Yvonne A. B.
Published: February 2023

Antecedentes: Existe amplia evidencia a favor de la aplicación de la Teoría de la Conducta Planificada a la higiene oral que demuestra ser una propuesta flexible y altamente explicativa. Sin embargo, se requiere mayor evidencia de la pertinencia de dicha teoría en su versión extendida al aplicarse en diversos grupos poblacionales de países suramericanos. Objetivo: Analizar los indicadores psicométricos del Cuestionario de Higiene Oral, instrumento desarrollado por Bunnk-Werkhoven, así como determinar el nivel de predicción de las variables de la Teoría Extendida de la Conducta Planificada aplicado al comportamiento en la higiene oral. Métodos: Se realizó un estudio no experimental de corte transversal en el que se encuestó a una muestra no probabilística de 644 estudiantes universitarios peruanos, quienes completaron el Cuestionario de Higiene Oral. Resultados: Existen coeficientes de confiabilidad aceptables y buenos para las subescalas del Cuestionario de Higiene Oral y el Análisis Factorial Confirmatorio (CFA) reveló que los ítems que comprenden el instrumento de medición se ajustan a un modelo de medida estandarizado de cuatro constructos exógenos de primer orden. En cuanto al modelo estructural, se aplicaron estadísticos de ajuste absoluto, comparativo y parsimonioso. Asimismo, las variables de la Teoría Extendida de la Conducta Planificada explicaron el 31 % y 26 % de la varianza en la intención, así como el comportamiento en higiene oral. Conclusiones: El modelo de medición y estructural basado en la Teoría Extendida de la Conducta Planificada presenta evidencia empírica favorable para aplicarse al comportamiento en higiene oral en estudiantes universitarios peruanos.
Investigation of Conjugate Effects on Forced Convection in Diamond (Diverging–Converging) Microchannels
Authors: Goli Sandeep , Saha Sandip K. , Agrawal Amit
Published: February 2023

A three-dimensional solid–fluid conjugate model is employed to provide physical insights into the effect of wall conduction on fluid convection in a diamond-shaped microchannel. The study covers the effect of divergence-convergence angle, width ratio, thermal conductivity ratio, thickness ratio, and Reynolds number on peripheral heat flux, temperature, and Nusselt number profiles. Isotherms show a multidirectional thermal gradient for low thermal conductivity ratios, whereas only an axial thermal gradient is seen for higher thermal conductivity ratios. Furthermore, the overall axial surface temperature gradients decrease with increasing divergence-convergence angle and decreasing width ratio. The study also shows that the thermal conductivity ratio significantly influences the Nusselt number, while the thickness ratio has only a moderate influence for all geometries. The analysis also reveals that at a particular intermediate thermal conductivity ratio, the Nusselt number becomes maximum. Lastly, a nondimensional wall conduction number is used to characterize conjugate effects in diamond microchannels. The wall conduction effect is inconsequential in diamond microchannels when the nondimensional wall conduction number is less than 0.01. The present study is beneficial from a practical perspective as it helps design the optimum channel geometries subjected to conjugate effects for many heat transfer applications.
Three 2-DOF 1T1R and One 3-DOF 2T1R Full-Hinged Novel Parallel Mechanisms With Zero Coupling Degree and Motion Decoupling: Design and Analysis
Authors: Li Ju , He Hongbo , Wu Guanglei , Li Tao , Shen Huiping
Published: February 2023

This paper presents the design and analysis of a family of full-hinged partially-decoupled novel parallel mechanisms (PMs) featuring one/two translation(s) and one rotation (1T1R/2T1R). First, three 2DOF 1T1R and one 3DOF 2T1R novel spatial PMs are proposed, according to topology design theory of PM based on position and orientation characteristic (POC) equations. The 3DOF 2T1R PM is illustrated to show its topological characteristics, such as POC set, degrees-of-freedom (DOF), and coupling degree (k), which show that the PM does not produce parasitic motion, with the coupling degree k being equal to zero. Second, the kinematic and dynamic performances of the 3DOF 2T1R PM are analyzed, including symbolic forward position solutions based on its topological characteristics, the workspace based on both the forward and inverse position solutions, respectively, the singular configurations based on the inverse position solutions, and the dynamic analysis built by means of the virtual work principle based on the single-open-chain units. Finally, the potential application of the proposed 3DOF 2T1R PM, namely, lifting and transferring lightweight workpieces between two perpendicular conveyor belts on the floor, is introduced.
Skin Cooling of Turbine Airfoils by Single-Wall Effusion—Part II: Computational Fluid Dynamics Validation and Preliminary Design Optimization on a Micro-Turbine Vane
Authors: Lange Yair , Kırmızıgöl S. Fatih , Acarer Sercan , Cukurel Beni
Published: February 2023

A reduced-order model (ROM) is developed to capture conjugate aero-thermal physics of effusion cooling in an entire micro-turbine vane/blade. The model considers a single-wall effusion scheme with internal boundary layer flow between the shell and an inner core. Coolant is supplied inside the leading edge and spread to both suction and pressure sides. The compound effect of multiple effusion rows is used to calculate spanwise-averaged cooling effectiveness. Metal temperature is modeled both in streamwise and shell thickness directions. The development of the model and a number of numerical/experimental validation cases are presented in detail in Part I. Part II of the work is geared toward the application of this method to skin cooling of a turbine airfoil by single-wall effusion. The reduced-order model, with all its subroutines functioning together, is validated against a higher fidelity 3D Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) solution. It is shown that the model can predict the main features of the combined internal and effusion cooling in gas-turbine blades at a computational cost which is 105 times lower than RANS (∼1 month with 700M elements and 24 modern Xeon Cores) on a whole turbine vane/blade. Due to this great advantage in speed, a design optimization is then accomplished toward minimizing coolant flow rate while keeping thermal gradients and temperature of the solid within acceptable levels. Implementing this scheme on a typical micro-gas-turbine vane, optimal distributions of the effusion-hole pitch and diameter are found within a given set of constraints. This preliminary design tool potentially enables wider and more efficient usage of effusion cooling in turbine vanes/blades.
Research on Parasitic Power of Cooling Balance of Plant System for Proton Exchange Membrane Fuel Cell
Authors: Chang Guofeng , Xie Chengyu , Cui Xian , Wei Pengnan
Published: February 2023

In high-power systems of proton exchange membrane fuel cells (PEMFC), cooling systems for the balance of plants (BOP) play an extremely important role in maintaining the temperature of the key components of the fuel cell system. To evaluate the effect of the PEMFC BOP cooling system on the fuel cell system efficiency, a Simulink model of the fuel cell system and an AMEsim model of the cooling system for the BOP system are established based on experimental data. A co-simulation is conducted based on the established models to determine the effects of fuel cell stack output power, coolant flowrate, radiator fan speed, and temperature control strategies on the parasitic power consumption and fuel cell system efficiency. The simulation results show that with an increase in the stack output power, coolant flowrate, and radiator fan speed, the parasitic power of the BOP cooling system increases and the system efficiency of PEMFC decreases. With an increase in the opening temperature of the radiator fan, the parasitic power of the BOP cooling system decreases and the system efficiency of the PEMFC increases. Compared with the rule-based control strategy, the radiator fan speed control strategy based on the PID controller achieves lower parasitic power. The research presented in this paper is helpful for further development of efficient fuel cell vehicle thermal management system.
Using Freeze-Casting Method to Create Lamellar Copper Structures – An Experimental Study of the Freezing Behavior of Cupric Oxide Colloidal Suspensions
Authors: Kasprzak Christopher , Hoffman Christina , Chen Ruey-Hung , Zhu Liang , Ma Ronghui
Published: February 2023

This study investigates the directional solidification behavior and the effects of initial freezing temperature on the formation of porous structure. The aqueous suspension with 10 vol.% cupric oxide (CuO) particles is prepared by mixing CuO particles, polyvinyl alcohol, and polyvinylpyrrolidone in deionized water. Additionally, potassium hydroxide is used to adjust the pH values between 8–10. Based on the measurement of the suspension viscosity, the optimal amount of the dispersant and the range of pH values that enable a well dispersed and stable suspension is identified. The freezing curves of the suspensions are measured to obtain the freezing point of the suspension as well as the effect of the potassium hydroxide on the freezing behavior. The suspensions then undergo directional freezing under various initial freezing temperatures. After sublimation under a near vacuum pressure, the green samples are infiltrated with epoxy to facilitate visualization and characterization of the pore morphology and orientation using an optical microscope. We believe that the obtained relationship between the freezing conditions, and the structural specifics of freeze-cast porous CuO lays the groundwork for freeze-cast porous copper with desirable pore morphology and structures for thermal management and energy storage applications.
Grid-Video Measurement Method for A-UGV’s Small Obstacle Avoidance Performance
Authors: Yoon Soocheol , Bostelman Roger , Virts Ann
Published: February 2023

With the advancement of factory logistics into the autonomous era comes the need to validate the safety and performance characteristics of Autonomous-Unmanned Ground Vehicles (A-UGVs) working in these application spaces ASTM Committee F45 has been developing standards for A-UGV performance measurement in various domains. The object detection and obstacle avoidance performance of A-UGVs in factories needs to be managed carefully as the action may cause severe damages, particularly when obstacles are either not detected or erroneously detected. In this paper, the grid-video measurement method is proposed to measure the small (e.g., short and/or thin) obstacle avoidance performance of A-UGVs. First, this paper describes the need for measuring the A-UGV performance through examples of small obstacles and the required A-UGV capability to avoid them. Next, the grid-video measurement method is introduced as a low cost, standard method to measure the small obstacle avoidance performance of A-UGVs. An experiment using blocks demonstrates how the grid-video measurement method can be used effectively to measure the A-UGV obstacle avoidance performance, and it shows that the performance changes upon A-UGV specification, obstacle sizing, and environmental conditions quantitively. The method and experimental results proposed in this paper will be used to support ASTM F45 standard development.
Micro-Crack Formation in Laser Structuring of Titanium Alloys for Orthopedic Applications
Authors: Yang Can , Fu Yunxiang , Liu Xiao-Hua , Yin Xiao-Hong , Liu Kewei , Li Chun-Bo , Zheng Xiuhong , Yang Bao-Hua
Published: February 2023

Titanium alloys have been widely employed as essential raw materials for manufacturing implants in orthopedics due to their excellent biocompatibility, corrosion resistance, and mechanical properties similar to human bones. In order to form effective bonding between the titanium alloy implant and the human bone at an appropriate time, micro-structures are required to create on titanium alloy surfaces through surface modification, so that the bone cells can propagate and grow. Laser-induced micro/nano hierarchical structures on titanium alloy implants are capable of improving the adhesion, arrangement and proliferation of osteoblasts. However, significant micro-crack appears on the metal surfaces after the nanosecond laser treatment, which will do harm to mechanical and corrosion resistance performances of the implants and may even in turn damage patients’ health. This work aims at investigating the formation mechanism and influencing factors of micro-cracks to achieve laser-structured titanium alloy implants with reduced or even no micro-crack for orthopedic applications. Laser ablation experiments were conducted on titanium alloy surfaces to produce micro-grooves/protrusions. Specifically, three key laser process parameters such as the laser scanning speed (v), laser frequency (f), and scan repetition (n) were considered in terms of their influences on the crack morphology. The smaller the laser scanning speed, the large the micro-crack number and the more chaotic of their distribution. The speed of nanosecond laser processing should be increased to reduce the generation of micro-cracks. It can be inferred that micro-cracks on laser-structured titanium alloy surfaces are mainly ascribe to the generated thermal stress during laser processing.
On the Observability of Quantum Dynamical Systems
Authors: Griffith Tristan D. , Gehlot Vinod P. , Balas Mark J.
Published: February 2023

Quantum statistical mechanics offers an increasingly relevant theory for a wide variety of probabilistic systems including thermodynamics, particle dynamics, and robotics. Quantum dynamical systems can be described by linear time invariant systems and so there is a need to build out traditional control theory for quantum statistical mechanics. The probability information in a quantum dynamical system evolves according to the quantum master equation, whose state is a matrix instead of a column vector. Accordingly, the traditional notion of a full rank observability matrix does not apply. In this work, we develop a proof of observability for quantum dynamical systems including a rank test and algorithmic considerations. A qubit example is provided for situations where the dynamical system is both observable and unobservable.
Investigating the Effect of Uniaxial Stress on Guided Wave Propagation in Plates by Wave Finite Element Method
Authors: Zhang Xu , Liu Gang , Chen Lei
Published: February 2023

As an important part of long-range nondestructive testing and structural health monitoring technology, ultrasonic guided wave technology has been used in a wide range of applications in aerospace, petrochemical, transportation, and other fields. This paper extends the previously developed wave finite element method by introducing the prestressing effect in Murnaghan hyperelastic materials and solving the dispersion curves of prestressed waveguide structures. Furthermore, this paper proposes a mode-tracking algorithm based on image sequential alignment that can achieve the multi-mode classification of guided wave dispersion curves and compare the changes in propagation characteristics of different guided wave modes. The results reveal that the change in guided wave phase velocity produced by prestressing is related to the applied stress, frequency-thickness product, and propagation direction and that the susceptibility of different guided wave modes to prestress varies. Finally, the model approach is validated by comparing its predictions to theoretical results from the literature, which match remarkably well. This study is an important guideline for the preferential selection of environmentally insensitive guided wave modes and excitation frequencies, correction of detection signals, and accurate assessment of engineering structure damage information in ultrasonic guided wave technology engineering applications.
Open-Source Virtual Labs for Undergraduate Mechanical Vibrations and Control Theory Courses
Authors: Contreras-Esquen Andrea , Utschig Tristan , Tekes Ayse
Published: February 2023

The vast majority of undergraduate engineering students struggle to acquire a deep understanding of complex topics presented in mechanical vibrations and control theory courses due to their highly mathematical nature, limited resources on the use of commercially available turn-key laboratory equipment, and lack of innovative teaching tools to improve student understanding. In this study, we developed open-source standalone virtual laboratory exercises for vibrations and control theory courses using Matlab Simscape. The virtual labs enable students to change the system parameters, develop a feel of the material, and record and observe the system response through mechanics explorer.
Assessment of Cooling Technologies for Solar Photovoltaic Panels Accounting for Local Solar Irradiance and Ambient Temperature Conditions
Authors: Lucas Aguilar Marcelo , Celis César
Published: February 2023

The growing energy demand and climate change emphasize the need to continuously use environmentally friendly energy sources. Consequently, renewable energy sources such as solar energy, which relies on the use of photovoltaic modules, have become popular in recent years. Photovoltaic (PV) modules convert the incident solar irradiance to electric energy. In such devices, by reducing the operating temperature, the associated solar energy conversion efficiency can be increased, and their lifetime extended. Accordingly, to compare their impact on the performance of PV modules, three different cooling methods, all of them coupled to a thermoelectric (TE) generator, (i) natural cooling, (ii) forced air cooling, and (iii) water cooling, are assessed. To evaluate the referred cooling methods, a computational model describing the behavior of the studied cooling methods is initially developed. Then, a PV model accurately predicting the behavior of commercial PV modules is developed and coupled to the cooling methods one. Finally, accounting for local ambient conditions and system operation over the course of one year, several simulations of PV modules with and without cooling systems are carried out using the developed tool. The main results indicate that some cooling techniques are adequate for some months of the year only, whereas the others do so for the remaining months. Indeed, PV module temperature reductions of up 7.7% and system efficiencies of up to 17.2% are observed. One of the particularities of this work relates to the use of local ambient conditions and system operation over a whole operating year.
An Evolutionary Aeroelastic Design Approach for Spars and Ribs of Flying Wing Aircraft
Authors: Moshtaghzadeh Mojtaba , Rangel Natalia , Bejan Adrian , Mardanpour Pezhman
Published: February 2023

The purpose of this paper is to examine how rib configurations and spar configurations influence flying wing stability. Flying wing aircraft exhibit enhanced flutter characteristics when stresses flow smoothly through the wing. We prevent stress strangulation through spar cross-sections by changing the configuration in the plunge direction. We employ and develop computer programs Gmsh, Variational Asymptotic Beam Sectional Analysis, MATLAB scripts, and Nonlinear Aeroelastic Trim and Stability of High Altitude Long Endurance Aircraft. The configurations are designed by considering the same material, mass, and flight conditions. The results indicate that the design with the smoother stress distribution through the wing has a higher flutter speed. It is shown that the σ11 and Von-Misses stress distributions have an important effect on the stability of a flying wing aircraft.
CFD Modeling of Interstitial Fluid Flow in Subcutaneous Adipose Tissue
Authors: Mokhtar Wael , Lubbers Ryan
Published: February 2023

Adipose tissue is a very important biologic component to nutrient storage and transport. The tissue and flow mechanics of the fluid within the extracellular space is not currently well understood, and difficult to study by experimentation, but could be studied through the development of a mathematical model of the anatomical domain. The study therefore was completed in order to develop a computational fluid dynamics (CFD) model to simulate the interstitial fluid flow in adipose tissue. Various characteristics of the tissue had to be defined by research and experimentation in order to create the model including, but not limited to, the domain size, tissue characteristics, capillarization within the tissue, and oncotic pressure distribution that drives the interstitial flow. The CFD model developed to simulate the interstitial flow within adipose tissue yielded a maximum fluid velocity of 1.85 μm/s, which was found to be within the range of published observed interstitial fluid flow velocities. Also, the model showed that capillarization of the tissue has a large effect the interstitial fluid flow mechanics and pattern in the extracellular space of the adipose tissue. This CFD model development could be used to further adipose tissue understanding as well as drug delivery kinetics in the region.
Effects of Residual Stresses Caused by Turning on Probabilistic Risk of Aeroengine Titanium Disks
Authors: Li Guo , Cai Wenhao , Zhou Huimin , Liu Junbo , Ding Shuiting
Published: February 2023

The residual stresses generated during the manufacturing process of aero-engine life-limited parts, such as turbine disks, affect the formation of cracks and thus influence the risk of failure. This study proposes a probabilistic risk assessment method for titanium aero-engine disks considering the residual stresses caused by turning. Specifically, a turning simulation model is firstly established by ABAQUS, and the residual stresses on the turning surface are obtained by conducting numerical analysis. Then, with the work stresses of a typical titanium turbine disk, the residual stresses are input into the failure probability evaluation model. Last, based on linear elastic fracture mechanics analysis, the crack propagation calculation is conducted, and the probabilities of failure of the disk are carried out. The results show that after considering residual stresses introduced by turning, the failure risk of the disk has declined. The probability of failure is predicted to reduce by nearly 8% under turning. The proposed method predicts the failure risk more accurately and is thus beneficial to the guidelines for the safety assessment of turbine disks.
A Multi-Scale Model for Microstructure Evolution During a Multi-Material Additive Manufacturing Process
Authors: Abubakar Abba A. , Al-Athel Khaled S. , Akhtar Syed S. , Abubakar Abdulazeez
Published: February 2023

Powder-based additive manufacturing (AM) technologies are commonly used to fabricate intricate-shape three-dimensional (3D) composite parts. The present study provides further insights into powder melt pool behavior and microstructure evolution during additive manufacturing of Hastelloy(HX)/WC composite using sequentially coupled multi-scale models. At the macro-scale, the heat transfer model is used to predict the temperature distribution and melts pool geometry formed during laser heating of multi-material powder bed. At the mesoscale, the phase-field and heat transfer models are coupled to predict the evolution of grains during the solidification of the powder melt. The computational results are reasonably comparable to that of the experiments. It is found that an ellipsoidal melt pool shape is formed around the irradiated zone. The temperature, thermal gradient and cooling rate changes across the melt pool dimensions. Due to epitaxial growth, columnar (elongated) grains are developed near the solid-liquid interface. In contrast, equiaxed grains are formed near the top regions of the melt pool due to higher cooling rates. The elongated grains become split into equiaxed ones due to the presence of the WC particles. The presence of the larger WC particles enhances the cooling rate; thereby, resulted in grain refinement. Reducing the WC particle size still results in grain refinement due to the pinning effect on grain boundaries; however, the grain size becomes affected by the WC particle size. The inclusion of foreign particles could be used to inhibit anisotropic behavior in 3D printed parts.
A New Approach to the Study and Prevention of the Clutch Judder
Authors: Tentarelli Manuel , Cantelli Stefano , Sorrentino Silvio , De Felice Alessandro
Published: February 2023

The clutch judder observed in hydraulically actuated dual clutch transmissions cannot be fully explained by the current scientific literature.

Using a new methodological approach for the analysis of clutch judder, this study shows that a fluctuating oil pressure makes the clutch a parametrically excited system and gives rise to regions of instability as a function of the operating conditions of the clutch.

The system’s dynamic behaviour, characterized by both mechanical and structural high complexity, is here investigated through stability analysis of a mathematical model of the driveline. In particular, stability boundaries are identified by means of Floquet analysis, as well as the occurrence of both parametric resonance regions and linear resonance conditions.

This opens a new perspective on NVH of automotive drivelines, showing that clutch judder can potentially occur in a much wider range of conditions than documented in the current scientific literature.

The results of the experiments in progress on a test bench, designed in partnership with CNH Industrial, are validating the proposed model and will allow to calibrate the parameters of a predictive mathematical model to avoid the phenomenon of clutch judder in the design phase.
Stability Analysis of Parametrically Excited Isotropic Rotors on Anisotropic Supports
Authors: De Felice Alessandro , Sorrentino Silvio
Published: February 2023

The stability of slender rotors which are parametrically excited by external loads is studied under the effects of an-isotropic supports. An axisymmetric shaft is considered, described by scaling a spinning Timoshenko beam, carrying a disk and loaded by oscillating axial end thrust and twisting moment. The supports are modelled including ‘principal’ stiffness and damping distributions, able to modify the closely separated modes generated by angular speed (with ‘splitting’ of eigenfrequencies in forward and backward pairs). The proposed model includes all the general features of slender rotors which are relevant for this kind of stability analysis, gyroscopic effects comprised. Stability is studied after discretization of the equations of motion into a set of coupled ordinary differential Mathieu-Hill equations. The influence of angular speed combined with anisotropy in the supports is analyzed with respect to frequency and amplitude of the external loads on stability charts in the form of Ince-Strutt diagrams. The occurrence of different kinds of critical solutions, simple and combination, is investigated, highlighting their dependency on both the degree of anisotropy in the supports and angular speed.
Method for Improved Alignment of Large Area, Unstructured Sandy Desert 3D Elevation Maps Acquired by LiDAR Aerial Mapping With GNSS RTK Fixed GPS
Authors: Bjelotomic Marko , Subramaniam Prashanth , Khalil Mohamad , Mohammed Abdallah Nasir Abdo , Nikolakakos Iraklis , Weston Michael , Anzil Mohammed Minhas , Almaeeni Khuloud
Published: February 2023

This paper explores the possibilities of alignment methodologies using software tools, regardless of the industry they are intended for. We present a comparison of several methods for the alignment of temporal 3D elevation maps using commercially available software as compensation for the GPS tagging inaccuracies. Through the process of 3D elevation map alignment, the capabilities of seemingly unrelated software tools for aerial mapping are explored and compared. This paper presents the workflow capabilities of CAD inspection programs, reverse engineering software, and map analysis software tools approaching the 3D elevation maps as 3D models and maps at the same time. Furthermore, the utilization of enduring features — like vegetation instances occurring sparsely in some desert environments is studied in terms of suitability to provide a ground reference. Vegetation occurrences, which seldom grow in the deserts of the Arabian Peninsula, are inappropriate for precise mapping by LiDAR. Nevertheless, they create a prominent point cloud that may be used as a reference feature under specific consideration. Better map alignment allows for better 3D elevation map comparison, leading to further research of sandy deserts and their fluid-like behavior to increase renewable energy generation in such environments.
Research of Task Complexity Decision System for Manual Assembly Tasks Using Fuzzy Cognitive Maps to Construct Bayesian Networks
Authors: Xuan Zhao , Shengen Zheng
Published: February 2023

With the evolution towards intelligent manufacturing, Industry 4.0 has revolutionized and gradually improved product quality and efficiency. When applied to the assembly sector, Assembly 4.0 has also attracted widespread attention. Assembly 4.0 requires lean production, automated learning, and the ability to solve real-time design decisions through technology and convert the direct labor of operators into management information and decisions. Therefore, to better assess the complexity of manual assembly tasks, we believe it is necessary to build a multi-view and multi-dimensional decision-making system from the perspective of manual assembly. For this purpose, we propose in this study, a Bayesian network model based on fuzzy cognitive maps. Simultaneously, we use Genie3.0 to build the Bayesian network model. For optimum quantization parameter values as well as conditional probability directions’ optimization between the parent node and the child node of the Bayesian network, we use the max-min hill-climbing (MMHC) algorithm and the Expectation Maximum (EM) algorithm. The influencing factors can be managed through the Bayesian network using this model, and the users can fully understand the changing rules among task complexity factors. This model can also provide theoretical and technical support for users, starting from the initial stage of product conception down to the completion of production.
Numerical Study and Validation of Hot Metal Desulfurization Using Calcium Carbide in the Ladle
Authors: Guo Xipeng , Mao Congshan , Walla Nicholas , Silaen Armin K. , Zhou Chenn
Published: February 2023

Hot metal desulfurization using lance injection in the transfer ladle is widely used in the industry. Many mathematical models are developed based on the thermodynamics, mechanism, and kinetics of hot metal desulfurization by using different reagents, but these works are often based on 1D calculation. In this work, a 3D transient Computational Fluid Dynamics (CFD) model is developed to simulate hot metal desulfurization (HMD) using calcium carbide in the experimental scale ladle. The capacity of the ladle is 70 kg, and the iron temperature is 1623.15 K. The efficiency of reagent particles penetrating carrier gas bubbles is considered. The model is validated with experiment work with an average difference of 6.8%. The effects of two different calcium carbide particle sizes and two different iron temperatures on desulfurization rates are discussed. The results show that smaller calcium carbide particles and higher iron temperatures can benefit the hot metal desulfurization rate.
Effect of Cell-Wall Angle on the Mechanical Properties of 3D-Printed Hierarchical Re-Entrant Honeycomb
Authors: Zhan Chi , Li Mingzhe , Lu Weiyi
Published: February 2023

Both hierarchical and auxetic structures have shown unusual mechanical properties and draw great attention for multiple engineering applications. Recently, a triangular 2nd order of hierarchy has been successfully integrated into re-entrant honeycomb, one specific type of auxetic structures, by the emerging additive manufacturing method. The resulted hierarchical re-entrant honeycomb (H-ReH) outperforms the conventional re-entrant honeycomb (C-ReH) in stiffness, initial buckling strength, densification strain and specific energy absorption capacity (SEA). However, the optimized designs of the cell structures in H-ReH are still elusive and yet to be explored, which is critical for advanced safety applications. The mechanical performance and deformation mode of H-ReH are mainly determined by the geometric parameters of the structure, among which the cell-wall angle is one of the most critical design parameters.

To this end, we designed H-ReHs with three different cell-wall angles, i.e. 60°, 75° and 90°. C-ReHs with the same three angle designs were processed through the same 3D-printing method as reference samples. The mechanical performance of the fabricated specimens was characterized by the uniaxial quasi-static compression tests. The evolution of the strain field in all the samples was measured and analyzed by the Digital Image Correlation (DIC). The results show that the angle designs have significant influences on the elastic modulus, strength, structural stability, and SEA of H-ReH. By increasing the angle from 60° to 75°, the densification strain and the SEA are increased by 60% and 75%, respectively. This is due to the altered deformation modes of the H-ReHs with different cell-wall angles. By contrast, the C-ReHs are found to be nearly inert to the angle change, due to its bending-dominated behavior regardless of the cell-wall angle change. When further increase the cell-wall angle to 90°, both H-ReH and C-ReH exhibit notable enhancement on the elastic modulus and the strength, but at a much-compromised structural stability. The vertical member of both structures buckles and fractures at a small strain.

In conclusion, this study has demonstrated that the mechanical properties of H-ReH is sensitive to the cell-wall angle. Furthermore, the H-ReH has much better mechanical tunability over C-ReH through the angle designs due to its unique deformation mechanisms. These findings will guide the future design of H-ReH and other types of lightweight robust materials and structures.
On the Accuracy and Efficiency of Convolutional Neural Networks for Element-Wise Refinement of FEM Models
Authors: Petrolo Marco , Iannotti Pierluigi , Pagani Alfonso , Carrera Erasmo
Published: February 2023

In this paper, a new methodology for the choice of the best structural theories through Machine Learning (ML) techniques is described, with a particular focus on composite shells. The identification of the most adequate theory can be operated very efficiently using Convolutional Neural Networks (CNN) as surrogate models to replicate the performances of a Finite Element (FE) formulation, although requiring only a small fraction of the usual amount of analyses. Enhanced by the introduction of the Carrera Unified Formulation (CUF), the FE Method (FEM) provides the results necessary for the training of the networks, while the Node Dependent Kinematics (NDK) approach opens to the practical implementation of local refinement capabilities. The evaluation of different structural theories is carried out with the Axiomatic/Asymptotic Method (AAM) and this can be done for both static and dynamic analyses, with The Best Theory Diagrams (BTD) being the outcome of this rating procedure. As shown in the results, CNNs can properly identify and reproduce the underlying connections between different sets of problem features and the accuracy of a given structural theory with just a very small amount of available reference data.
Low-Cost Portable High-Speed Data Logging
Authors: Kerr Colton , Rogers John
Published: February 2023

This research describes a low-cost design for high-speed, portable, and configurable data acquisition and logging. Drone launch from in-flight aircraft produces short-duration, impactlike peak stresses in aircraft structure. Testing environments such as on aircraft require portable data acquisition hardware systems. Commercially available data acquisition systems typically have at least one drawback of being expensive, not portable, not high speed, or not configurable. These drawbacks make it difficult to use commercial systems in field experiments such as on aircraft in flight. This research describes a data logging system that is low-cost (materials < $200), portable (< 1kg), has one single-ended high-speed analog input channel (20k samples/second), and a resolution of 12 bits. The microcontroller used is a Digilent WiFire board with a microchip PIC32MZ2048EFG100 microcontroller. This microcontroller is programmed using Simulink and is configurable in its sample rate, data type, number of channels, and resolution. Data are logged locally on an SD card using an open-source OpenLager device that was developed by drone racing company dRonin for high-speed data. Data logging is in binary format, and the 12-bit value is logged as two 8-bit (upper and lower) bytes due to limitations of the OpenLager. A MATLAB script reassembles the bytes in a postprocessing step. Performance of the prototype is compared to commercial data logging systems by simultaneous logging of one event. A hammer strike force-impulse experiment is used as a proxy for the stresses in aircraft structure during impact-like events. Conclusions and recommendations on the use of the new system and existing commercial systems are made based on the results of the experiments. The experiment was designed to log signals from a strain gage-Wheatstone bridge-amplifier system, but the prototype is configurable and may be used in any applications that require portable logging of voltage signals with sample rates in the 20 kHz range.
Domain Segmentation Optimization of Multiple Anisotropic Materials With Varying Orientation Angles Using a Topology Optimization Based on the Extended Level Set Method
Authors: Noda Masaki , Matsushima Kei , Noguchi Yuki , Yamada Takayuki
Published: February 2023

In this study, we propose a method to optimize a domain segmentation of multiple anisotropic materials having varying orientation angles (OAs). The feature of this method is that anisotropic materials having different OAs are considered as different materials for each angle and the domain segmentation is optimized. First, the formulation of a multi-material topology optimization problem is described in which anisotropic materials with different OAs are considered as different materials. Then, linear elasticity topological derivatives are calculated when an anisotropic material is replaced with a different anisotropic material. Subsequently, we outline a topology optimization method based on the extended level set method, which is used to solve the multi-material topology optimization problem. Finally, we apply the proposed method to a stiffness maximization problem and demonstrate its effectiveness using multiple numerical examples.
Comprehensive Analysis of Cyber-Manufacturing Attacks Using a Cyber-Manufacturing Testbed
Authors: Prasad Romesh , Moon Young
Published: February 2023

Cyber-Manufacturing Systems (CMS) are vulnerable to cyber-manufacturing attacks ironically because of its very beneficial advance: seamless integration with informational and operational entities. Beyond traditional cyber-attack practices, attackers against CMS have an enlarged attack vectors to penetrate CMS through and have a broader spectrum of eventual consequences. Although the significance of this new problem started being widely recognized, actual occurrences of cyber-manufacturing attacks — that can provide useful empirical data — have been relatively of a low number. Furthermore, recent research has been focused on developing solutions to prevent or detect cyber-manufacturing attacks. However, such solutions can be more effectively devised if a thorough understanding of the nature of various attacks is achieved first. To develop effective solutions against cyber-manufacturing attacks, it is of utmost important to understand motivations of the attacker, behaviors of the attacks, patterns of the attack, and impacts of these attacks. The comprehensive analysis of cyber-manufacturing attacks can be achieved by conducting an in-depth investigation of the attacks, identifying vulnerabilities caused by the attacks, and experimenting the attacks in a controlled CMS environment. This research presents how a cyber-manufacturing testbed can be utilized to achieve the above goal. It contributes toward the goal by accomplishing four tasks. First, it established a cyber-manufacturing system testbed. Second, the research identified attack surfaces in the designed testbed and performed an in-depth investigation for cyber-attacks that can infiltrate the established testbed. Based on the second task, it developed a ranking system. Finally, based on the ranking system, high-impact attack scenarios have been identified, demonstrated and analyzed on the cyber-manufacturing testbed.