bluuebunny/crossref_metadata_2025 huggingface dataset:
Galactoseismology in cosmological simulations
Authors: García-Conde B. , Antoja T. , Roca-Fàbrega S. , Gómez F. , Ramos P. , Garavito-Camargo N. , Gómez-Flechoso M. A.
Published: December 2023

Context. Complex models recently became available for studying the dynamics of disk galaxies such as the Milky Way (MW). These models include the global dynamics from dwarf satellite galaxies, dark matter halo structure, gas infall, and stellar disks in a cosmological context.

Aims. We use a MW model from a suite of high-resolution hydrodynamical cosmological simulations named GARROTXA to establish the relationship between the vertical disturbances seen in its galactic disk and multiple perturbations from the dark matter halo, satellites, and gas.

Methods. We calculated the bending modes in the galactic disk in the last 6 Gyr of evolution. We computed the vertical acceleration exerted by dark matter and gas in order to quantify the impact of these components on the disk, and compared this with the bending behavior with Fourier analysis.

Results. We find complex bending patterns at different radii and times, such as an inner retrograde mode with high frequency and an outer slower retrograde mode excited at different times. The amplitudes of these bending modes are highest during the early stages of formation of the thin disk (20 km s−1) and reach up to 8.5 km s−1 in the late disk evolution. We find that the infall of satellite galaxies leads to a tilt of the disk, and produces strong anisotropic gas accretion with a misalignment of 8° with subsequent star formation events and supernovae, creating significant vertical accelerations on the disk plane. The misalignment between the disk and the inner stellar and dark matter triaxial structure, which formed during the ancient assembly of the galaxy, also leads to a strong vertical acceleration of the stars. We also find dark matter subhalos that temporally coincide with the appearance of bending waves in certain periods.

Conclusions. We conclude that several agents trigger the bending of the stellar disk and its phase spirals in this simulation, including satellite galaxies, dark subhalos, misaligned gaseous structures, and the inner dark matter profile. These phenomena coexist and influence each other, sometimes making it challenging to establish direct causality.
The effect of winds on atmospheric layers of red supergiants II. Modelling VLTI/GRAVITY and MATISSE observations of AH Sco, KW Sgr, V602 Car, CK Car, and V460 Car
Authors: González-Torà G. , Wittkowski M. , Davies B. , Plez B.
Published: December 2023

Context. Mass loss plays a crucial role in the lives of massive stars, especially as the star leaves the main sequence and evolves to the red supergiant (RSG) phase. Despite its importance, the physical processes that trigger mass-loss events in RSGs are still not well understood. Recently, we showed that adding a semi-empirical wind to atmosphere models can accurately reproduce observed extensions in the atmospheres of RSGs, where the mass-loss events are taking place, particularly in the CO and water lines.

Aims. By adding a static wind to a MARCS atmospheric model, we computed synthetic observables that match new interferometric data of the RSGs AH Sco, KW Sgr, V602 Car, CK Car, and V460 Car obtained with the VLTI/MATISSE and VLTI/GRAVITY instruments between August 2022 and February 2023. We also used archival VLTI/AMBER data of KW Sgr and VLTI/GRAVITY data of AH Sco. The MATISSE wavelength range includes the SiO molecule at 4.0 μm with a spectral resolution of R ~ 500.

Methods. The model intensities with respect to the line-of-sight angle (μ) as well as the spectra and visibilities were computed using the stellar radiative transfer code TURBOSPECTRUM. We found the best-fit model, mass-loss rate, and best-fit angular Rosseland diameter for the observations. We simultaneously matched our model to the data, covering a wavelength range of 1.8–5.0 μm, which corresponds to the K, L, and M bands.

Results. Our models reproduce the spectro-interferometric data over this wide wavelength range, including extended atmospheric layers of CO, H2O, and SiO. We obtain a range of Rosseland angular diameters between 3.0 < θRoss < 5.5 mas and a range of mass-loss rates of −6.5 < log Ṁ/M⊙ yr−1 < −4 for our five targets. In our best-fit models, the partial pressure of SiO relative to the gas pressure, PSiO/Pg, and the SiO 4.0 μm line intensity increase between 2 and 3 stellar radii. The relative intensity depends on the luminosity used for our models, since the more luminous models have a higher mass-loss rate.

Conclusions. This work further demonstrates that our MARCS+wind model can reproduce the observed physical extension of RSG atmospheres for several spectral diagnostics spanning a broad wavelength range. We reproduce both spectra and visibilities of newly obtained data as well as provide temperature and density stratifications that are consistent with the observations. With the MATISSE data, we newly include the extension of SiO layers as a precursor of silicate dust.
Local estimates for vectorial Rudin–Osher–Fatemi type problems in one dimension
Authors: Grochulska Zofia , Łasica Michał
Published: December 2023

We consider the Rudin–Osher–Fatemi variational denoising model with general regularizing term and L2 fidelity in one-dimensional, vector-valued setting. We obtain local estimates on the singular part of the variation measure of the minimizer in terms of the singular part of the variation measure of the datum. In the case of homogeneous regularizer, we prove local estimates on the whole variation measure of the minimizer and deduce an analogous result for the gradient flow of the regularizer. We also discuss the question of extending our results to other fidelities.
Comparative analysis of ground source heat pump drilling construction techniques under complex geological conditions
Authors: Luo Ning , Liu Wei , Duan Yanglong
Published: December 2023

The buried pipe is an important part of the geothermal heat pumps system. One of the main reasons for the high initial installation cost of the ground source heat pump system is that its heavy drilling workload, long construction period and high cost account for the system cost. Especially in some complex geological conditions, the high proportion of drilling costs directly increase the overall cost of the geothermal heat pumps system, which to a certain extent restricts the popularization and application of geothermal heat pumps system. Based on the comparative analysis of different types of geological conditions and different ground source heat pump drilling technologies, this paper starts with the research and analysis of basic geological structure. On the premise of meeting the requirements of the system, this paper aims to improve the drilling efficiency and reduce the cost by rationally designing pipe Wells and optimizing the drilling technology scheme.
Research on The Evaluation of Technology Maturity in Multiple Scenarios for Hydrogen Fuel Cell
Authors: Tang Xiru , Wang Bin
Published: December 2023

Hydrogen, as an important clean energy source, is one of the key energy pathways for the future. Hydrogen fuel cells serve as the core carrier for the current terminal applications of hydrogen energy. Based on the S-curve evolution principle of the Inventive Problem Solving Theory, this paper establishes a technology maturity evaluation index system for the multi-scenario application of hydrogen fuel cells using the literature patent measurement method. A characteristic matrix for the evaluation index of technology maturity is designed, and the technology maturity of hydrogen fuel cells in two scenarios, namely transportation and building energy supply, in China is evaluated. The research results indicate that the application of hydrogen fuel cells in transportation scenarios in China is in the growth stage, while in building energy supply scenarios, it is still in the infancy stage. These findings contribute to accurately identifying the bottleneck stages of technology and market trends, thereby promoting the rapid development of fuel cell technology in China.
Optimization of Valve Flow Characteristics Based on Improved Particle Swarm Algorithm
Authors: Duan Bingde , Dong Lijiang , Gao Ning , Shen Zhongxin , Li Juan , Xu Hongyan
Published: December 2023

After long-term operation, the flow characteristics of the high-pressure regulating valve of a thermal power unit may be shifted to a certain extent, resulting in inconsistent changes in the total valve position and opening degree, which in turn affects the PFR function of the unit. Based on the historical operation data of a thermal power unit, the flow characteristics of the unit's high-pressure regulating valve are optimized using an improved particle swarm algorithm. By experimentally verifying the primary FM in different total valve position intervals, the influence of valve flow characteristics on the primary FM function is discussed. The results of the primary FM example show that, with the optimized valve flow characteristics, the output response index of the unit in 15 and 30 seconds is increased to 85.44% and 94.11%, respectively, which meets the assessment requirements of the grid-connected operation and management of the power plant for the primary FM, and optimizes the primary FM performance of the unit.
Optimization of drilling parameters based on Copula function method for the Chepai area
Authors: Liu Yingbiao , Xing Linzhuang , Xie Zhitao , Wang Chaofei , Zhu Zhongxi , Chen Chong
Published: December 2023

In areas with complex stratigraphic lithology, the relationship between the penetration rate and drilling parameters should be fully considered to optimize the drilling process and improve drilling efficiency. The most frequently utilized methods for performing parameter optimization through correlation analysis are the correlation coefficient, principal component analysis, and grey correlation. The correlation coefficient method solely evaluates the extent of linear correlation between two variables, it cannot be applied to the non-linear connection between penetration rate and drilling parameters. The application of principal component analysis may produce inaccurate experimental findings due to the intricate and poorly co-varying nature of drilling parameters. The grey correlation method can lead to the substantial bias in the results because of the vast quantity of data analysed. Based on the vast quantity of data, using the copula function, the big data analysis method analyses the nonlinear relationship between penetration rate and drilling parameters. It constructs a united distribution function expression to determine the optimal parameter selection criteria. The in-situ drilling data from dozens of wells in the Chepaizi area are collected and optimized six types of parameters. The optimal parameter combination is determined. Following field investigation, there was a noteworthy increase of 34.83% in the average penetration rate.
Electronic stability study of tin dioxide as a catalyst for lithium-air batteries
Authors: Maenetja Khomotso , Ngoepe Phuti
Published: December 2023

The production of unstable, irreversible discharge products which contributes to capacity fading still remains the main challenge that limits the practical use of Li-air batteries. To improve the electrochemical performance of the Li-air batteries, a clear understanding of the catalytic activity of SnO2 towards the production of stable discharge products is essential. In this study, we use the density functional theory calculation to investigate the bulk properties and surfaces stability of SnO2. The SnO2 bulk structure was found to be a stable semiconductor with a band gap of 0.63 eV. The phonon dispersion curves indicate that the structure is vibrationally stable since it shows no soft mode along the brillouin zone direction. The elastic constants show that our structure is mechanically stable since the C’ is positive and obey the mechanical stability criteria for a tetragonal crystal.
First principle studies on stability of reactive products of Li-O and Li-S batteries
Authors: Masedi Cliffton , Ngoepe Phuti
Published: December 2023

We investigated the phase stabilities of insoluble discharge products of oxygen and sulphur (Li2O, Li2S, Li2O2 and Li2S2 structures) formed in Li-O and Li-S batteries using density functional theory within the generalized gradient approximation. Their structural, electronic and mechanical properties were determined to show their stability trend. The lattice parameters were well reproduced and agree to within 1% with the available experimental data. We have found good correlation between the heats of formation, density of states, elastic constant and phonon dispersion curves. The heats of formation predict Li2O to be the most stable structure whereas Li2S2 is the least stable. Our phonon dispersion calculations show that Li2O, Li2S and Li2O2 structures are mechanically stable consistent with the elastic constants. The Li2S2 structure display soft modes associated mainly with sulphur atoms vibrations in the a-b plane, suggesting that the structure is unstable.
Recycling PA12 powder from laser powder bed fusion through producing filament for fused deposition modelling
Authors: van der Walt Jacobus , Fateri Miranda
Published: December 2023

The laser-powder bed fusion (L-PBF) process presents advantages over other polymer additive manufacturing processes in terms of part strength and high production rate possible with the technology. The high cost and limited re-use of nylon powder used in the process however limit the large-scale adoption of the technology in industry. This paper investigated the re-use of PA12 powder that is no longer suitable for the L-PBF process through producing filament for the fused deposition modelling (FDM) process. Results from the study showed that parts with good mechanical strength and reasonable dimensional accuracy can be produced using FDM.
An investigation on SWAAT and electrochemical corrosion behaviour of roll-bonded and brazed aluminium alloy - AA4045/AA3003
Authors: Moema Joseph , Siyasiya Charles , Morudu Veronica , Hadebe Nomsombuluko , Buthelezi Thokozani
Published: December 2023

The formation of Mn/Fe-containing precipitates during a high-temperature treatment known as homogenization is important for the downstream performance of AA3xxx aluminium alloys. There is currently a significant scientific and industrial interest in the use of Al-Si-Mn-Fe sheet alloys in automotive applications to reduce the weight of vehicles. This work is concerned with the precipitation of dispersoids, which occurs over several hours during heating and holding at the homogenization temperature. In this study, therefore, the effects of isothermal soaking time on the microstructure of AA3003 cladded with AA-045 alloy were investigated. The microstructures and intermetallic phases were analysed using optical microscopy (OM) and scanning electron microscopy (SEM). The seawater acetic acid test (SWAAT) and electrochemical corrosion test were used for studying the corrosion behaviour of the AA4045/AA3003 cladded alloy. The results on the effect of soaking time on both microstructure and corrosion properties of the brazed alloy are presented. The OM results show that the microstructure of these alloys consisted of an Al-Si eutectic phase at the surface of the residual clad and a thick diffusion zone which is a band of dense precipitates ( BDP) between the clad and core. The sheet surface reveals the presence of pitting corrosion on the coupons exposed for 30 days and more. The polarization curves of the corrosion tests show that the AA4045/3003 is susceptible to intergranular corrosion (IGC) as a consequence of the higher amount of grain boundary precipitates formed during the brazing process.
Regression analysis and optimization of direct energy deposition parameters for functionally graded 316L stainless steel-tungsten carbide coatings
Authors: Tendere Takudzwa Lewis , Sacks Natasha
Published: December 2023

In this study, the manufacturing of a two-layered functionally graded 316L stainless steel-tungsten carbide coating using directed energy deposition was investigated. The aim was to determine the optimal deposition parameters to achieve minimum porosity using a thickness of 1mm per layer. The input factors considered were laser scanning power and scanning speed, which were varied at different levels according to a full factorial design of an experimental matrix. To determine the optimum parameters regression analysis using analysis of variance was carried out. The optimum parameters were found at a laser scanning power of 607.4 W and a scanning speed of 8.5 mm/s for the first coated layer, and at a laser scanning power of 700 W and a scanning speed of 11 mm/s for the second coated layer. Minimum porosities of 0.0065 % and 0.0554 % were achieved for each coated layer respectively.
Plasma spheroidisation and characterisation of commercial titanium grade 5 powder for use in metal additive manufacturing
Authors: Nkhasi Nthateng , du Preez Willie , Bissett Hertzog
Published: December 2023

Low density, high strength, high corrosion resistance, and biocompatibility are some of the attractive characteristics of parts produced through additive manufacturing from Ti6Al4V powder. This alpha-beta alloy is the workhorse of the titanium industry, and it is applied for manufacturing of structural components of aircraft, hydraulic systems, engine components, helicopter rotor blades, rockets and spacecraft. In the study presented in this paper, a plasma spheroidisation process was used to develop spherical powder from irregularly shaped commercial titanium Grade 5 powder. Properties of the powder relevant to metal additive manufacturing, namely particle shape and size, chemical composition, flow characteristics and density, were determined to establish the usability of the developed powder. It was concluded that plasma spheroidisation of irregularly shaped Ti6Al4V Grade 5 powder for AM application was feasible for powder size ranges between 45 and 150 μm, because the oxygen content did not increase for size fractions in this range.
Spark plasma sintered Ti-35Nb-7Zr-5Ta-1Cu alloy
Authors: Nkuna Tinyiko Rose , Teffo Linda Moipone , Shongwe Mxolisi Brendon , Machaka Ronald
Published: December 2023

Beta-titanium alloys composed of non-toxic and non-allergic alloying elements are the material of choice for biomedical applications. The effects of Cu addition and heat treatment on the microstructural evolution and phase transformation of Ti-35Nb-7Zr-5Ta alloys were thoroughly investigated. The spark plasma sintering (SPS) was used to fabricate Ti-35Nb-7Zr-5Ta with a micro-addition of 1 wt.% Cu. Field Emission Scanning Electron Microscopy (FE-SEM) and X-ray diffractometry (XRD) were used to investigate microstructural evolution and phase transformation. Microstructures obtained include a predominant BCC β-phase and a two-phase area (α+β) with a large grain boundary of β-phase without the intermetallic phase, implying a positive effect on the mechanical properties of the alloy. The sintered alloys exhibited excellent corrosion resistance and may be suitable candidates for biomaterial applications.
Design of HERMES: a mobile autonomous surveillance robot for security patrol
Authors: Dickens John , Maweni Thabisa , Setati Tiro , Suddoo Zubair
Published: December 2023

The HERMES autonomous surveillance robot platform is a low-cost outdoor autonomous surveillance vehicle. It is designed to autonomously patrol outdoor areas performing surveillance and providing automated alerts of detected vehicles and people. The design and testing of this system are covered in this paper. The design philosophy focused on the use of off-the-shelf components wherever possible with the base of the robot being a modified electric quadbike. The testing has verified that the surveillance robot can perform real-time person and vehicle detection, video streaming, manual and autonomous navigation on a low-cost platform. The development of the robot platform is continuing with the current focus being on the improvement of the autonomous navigation, ingress protection (IP) rating and verification of the battery life.
Methods of workspace generation for parallel kinematic manipulators
Authors: Dharmalingum Wesley , Padaychee Jared
Published: December 2023

This paper presents the geometric, discretization and Monte Carlo method to generate the workspace for Parallel Kinematic Manipulators (PKMs). The geometric method does not require the solution to the inverse kinematics as opposed to the Monte Carlo and discretization methods. Each method possesses advantages and drawbacks concerning accuracy, time and ease of implementation. A case study concerning constant orientation workspace of a planar 3RRR PKM showed that the most efficient and accurate method was the geometric method but it also possessed the most limitations. The discretization and Monte Carlo methods produced the workspace with an accuracy of 92.49% and 95.67% respectively.
3D mapping and photogrammetry sensor payload for unmanned aerial vehicles
Authors: Purdon Kyla , van Niekerk Theo , Phillips Russel , Marais Stephen
Published: December 2023

Unmanned Aerial Vehicles (UAVs) have shown great potential for data collection and monitoring of areas. Sensors such as LiDARs and cameras can be used on UAVs for high-resolution data collection and used for various applications like Digital Surface Models (DSM), photogrammetry, inspection systems, and maintenance applications. This paper describes the design and implementation of a sensor payload for UAVs using a LiDAR sensor, camera, Inertial Measurement Unit (IMU), and Global Positioning System (GPS). The payload collects data that can be used to georeference LiDAR and camera data, which can later be used to generate a georeferenced map and perform object detection and classification.
Prototype design of an aerial robotic platform for indoor applications
Authors: Botha Natasha , van Eden Beatrice , Lehman Lodewyk , Verster Jaco
Published: December 2023

There is an increased interest in using aerial robotic platforms for indoor applications in industrial and manufacturing environments. One such example is stocktaking in warehouses, where the use of other mobile robotic systems is not efficient as they aren’t able to reach higher shelves or operate at the same speed as an aerial robotic platform. In this paper we discuss a prototype design for an aerial robotic platform that will be able to operate in GPS-denied areas, such as indoor warehouses. Suitable choices for the hardware and avionics are proposed based on the system and user requirements. The final design weighs 194 g, costs R 7 354.3, and has an estimated flight time of 5.5 min which is within the system requirements.
Evaluation of performance results for low-cost 3D printed myoelectric prosthetic devices during Cybathlon 2020 ARM discipline
Authors: Kirkman Daniel , Stopforth Riaan , Hands Clive
Published: December 2023

The performance of a low-cost 3D printed myoelectric prosthetic device known as the Touch Hand 4.5, at the 2020 Cybathlon competition is discussed. This device is under development as a low-cost prosthetic device for upper-limb amputees. The Touch hand team placed 13th out of 15 teams at the Cybathlon competition. By assessing the performance of the device and comparing with the performance of competitors, avenues of future research for the improvement of the Touch hand are identified.
Modular robotic arm for automation of SMME industrial press
Authors: Naicker Danny , Purdon Kyla , Ramruthan Kshir
Published: December 2023

Small South African manufacturing companies, endeavouring to benefit from Fourth Industrial Revolution (4IR) technologies, specifically automation, are restricted by exorbitant costs and the lack of know-how associated with automation. This project aims to develop affordable modular automation blocks that can couple with each other, using the OpenStructures grid, to provide customisable degrees of freedom tailored for specific automation applications. The cost of development is recovered, and the cost of maintenance is reduced through the reuse of these blocks over different automation applications. A key measure of effectiveness is a standardised mechanical and electrical interface for each block.
Model-Free trajectory planning for a rotary-wing unmanned aerial vehicle with an uncertain suspended payload
Authors: Hohbach Annika , Jordaan Hendrik Willem , Engelbrecht Japie
Published: December 2023

Payload transport using rotary-wing unmanned aerial vehicles (RUAVs) has grown in popularity. Suspending the payload from the RUAV expands the range of use cases but does so at the expense of changing the dynamics that may result in instability. This paper explores how a model-free solution can be used to plan robust trajectories that account for the added oscillations if the payload is varied. The twin-delayed deep deterministic policy gradient (TD3) algorithm is a model-free reinforcement learning method and is used to train an agent to be implemented as a local planner to plan optimal trajectories that can complete two defined circuits whilst minimizing the swing of the payload. A non-linear model predictive controller (NMPC) is implemented as a model-based solution to evaluate the capabilities of the model-free results determining its viability, without choosing a superior approach. The results indicate that the model-free TD3 agent has comparable results to the model-based NMPC for two defined circuits, with increased robustness to payload uncertainty when trained with different payload parameters.
4-RRS PKM for stabilisation on a mobile sensor platform
Authors: Ramruthan Kshir , Kuchwa-Dube Chioniso
Published: December 2023

Disturbances experienced by an inspection robot can reduce the quality of its sensor measurements, which can in turn negatively affect the robot’s functionality. This research aimed to design a Parallel Kinematic Mechanism (PKM) for use as a stabilisation mechanism. The research focused on designing, simulating, building, testing, and analysing the mechanism. The PKM was modelled and simulated using MATLAB®, designed and developed using NX CAD software, and it was tested using a custom-built test rig that could simulate rotational disturbances. Using the metric of absement, the PKM significantly reduced the disturbances, depending on the disturbance induced.
Design optimisation of TPU modular footwear for sustainable fashion: a South African Fashion Week case study, 2023
Authors: Havenga Sarel , van der Walt Philip
Published: December 2023

The fashion industry is continuously evolving, and Thermoplastic Polyurethane (TPU) produced modular footwear is emerging as a trend for sustainability. This study aims to optimise the design of TPU modular fashion footwear for the South African fashion sector. The practice-based case study investigated the factors that influence the design and manufacturing of modular footwear using TPU, with a focus on enhancing sustainability. A design framework was developed using CAD software and evaluated the effectiveness of the optimised design in enhancing sustainability through a case study conducted at the SA Fashion Week in 2023. A combination of quantitative and qualitative research methods was employed to collect and analyse data, contributing to the development of sustainable and fashionable modular footwear for the fashion industry. It further provides insights into the challenges associated with the design and manufacturing of TPU modular fashion footwear.
Effect of normal load on the wear and rolling contact fatigue behaviour of AAR class B wheel against R350HT rail in a twin disc simulator
Authors: Leso Tshenolo P. , Siyasiya Charles W. , Mostert Roelf , Moema Joseph
Published: December 2023

The normal load at the wheel-rail contact interface plays a significant role in wear and rolling contact fatigue (RCF) performance of both wheel and rail steels. In recent years, there has been an increase in axle loads due to increased demand for railway services. This study investigated the effect of normal load on the wear and RCF behaviour of the AAR class B wheel versus R350HT rail using a twin disc wear simulator. The mass loss, surface damage and depth of deformation were used to assess wear and RCF, respectively. From the mass loss results, wear maps were obtained to identify different wear regimes being mild, severe and catastrophic at different contact loads and slip ratios. Scanning electron microscopy was also used to assess the surface damage of wheel and rail steels in order to identify the wear regimes with surface cracking and delamination being observed at higher contact loads indicating severe and catastrophic wear. Furthermore, the RCF crack density was found to be higher on specimens evaluated at higher normal loads with more cracks evident and crack branching forming.
Hot corrosion effect of the vacuum arc melted (a2/γ)Ti-48Al-2Nb-0.7Cr-0.3Si alloy under an environment of NaCl-Na2SO4 salt
Authors: Magogodi Steven , Mathabathe Maria , Bolokang Amogelang , Siyasiya Charles
Published: December 2023

The Ti-48Al-2Nb-0.7Cr-0.3Si alloy comprising of α2-Ti3Al and γ-TiAl phases was successfully fabricated using vacuum arc melting. To study its hot corrosion behaviour, the alloy was subjected to cyclic thermal loading under a Na2SO4 + 25wt.%NaCl molten salt mixture at 900 °C for up to 60 h. Mass change per unit surface was measured to determine the corrosion kinetics of the alloy. The alloy experienced severe hot corrosion attacks up to -50.94 mg/cm2. SEM indicated the formation of a mixture of TiO2/Al2O3 scales on the alloy's surface. XRD confirmed the presence of hot corrosion products such as Na2Ti3O7, TiO2, Al2O3, and Cr2O3. The presence of chlorine gas in the hot corrosion environment resulted in the delamination of the protective scale on the surface, indicating its detrimental effect.
The effect of Ni-doping on the stability of Li2MnO3 cathode material: a DFT study
Authors: Mphahlele M. G. , Masedi M. C. , Malatji K. T. , Ngoepe P. E. , Ledwaba R. S.
Published: December 2023

The density functional theory with Hubbard parameter (DFT+U) incorporated within the Vienna Ab Initio Simulation Package was utilized to investigate the structural, electronic, elastic, and dynamical properties of pristine and Ni-doped Li2MnO3. The cluster expansion technique was used to generate the doped phases of Li2MnO3. The binary phase diagram predicted Li2Mn0.83Ni0.17O3 as the most stable phase with the lowest heat of formation. The study shows that Li2Mn0.83Ni0.17O3 is more thermodynamically stable than Li2MnO3 with a lower heat of formation. Additionally, the density of states showed that Li2Mn0.83Ni0.17O3 has a narrower band gap of 1.54 eV compared to the undoped structure with a band gap of 1.89 eV which leads to a higher electrical conductivity of the material. The elastic constants show that both structures are mechanically stable and lastly the phonon dispersions showed that these structures are vibrationally stable with no presence of imaginary vibrations. Finally, based on the results, Li2Mn0.83Ni0.17O3 can be proposed as potential cathode materials for use in lithium-ion batteries.
The size and temperature effect on titanium Ti7 cluster in β-TiCl3 medium
Authors: Mazibuko Andile , Ngoepe Phuti , Chauke Hasani
Published: December 2023

In the Kroll process, the reduction process results in the production of intermediates such as titanium trichloride (TiCl3) and titanium dichloride (TiCl2). There has been experimental work on developing a continuous reduction process using TiCl3 and TiCl2. However, more investigations still need to be done to understand these mediums and their interactions. In this paper, we will be investigating one TiCl3 polymorph as a potential medium for titanium production. We employ the DL_POLY code to understand the effect of temperature on the Ti7 cluster using a stable β-TiCl3 medium. It was observed from the total energies that the system is stable at 50 – 700 K. The diffusion coefficient results showed that the Ti7 nanocluster diffuses faster than Ti and Cl at 1300 – 2000 K.
Assessing the impact of process parameters on lattice structure manufacturing defects through micro-CT scanning
Authors: Park Minsol , Venter Martin Phillip , Du Plessis Anton
Published: December 2023

In this study, we examined the impact of process parameters on the manufacturing defects in micro-strut lattice structures produced via Laser Powder Bed Fusion (L-PBF). By intentionally varying parameters like laser power and layer thickness, we investigated how these changes affect internal pores, surface roughness, and geometry discrepancies. To quantify these defects, micro-CT (Computed Tomography) scanning analysis was utilised. Our findings demonstrate that manufacturing defects in lattice structures are highly sensitive to variations in process parameters. The results of this study shed light on how process parameters can be adjusted to improve the quality of micro-strut lattice structures.
Implementing digital twinning in an additive manufacturing process chain
Authors: Thejane Kekeletso , du Preez Willie , Booysen Gerrie
Published: December 2023

Additive manufacturing (AM) is defined as the process of joining materials layer by layer to produce a part. The Centre for Rapid Prototyping and Manufacturing (CRPM) of the Central University of Technology, Free State has successfully established an AM process chain to produce qualified medical implants. The process chain complies with the international standards ISO 13485:2016 and ISO 14971:2012, which certify the repeatability and reliability of processes. Despite the significant achievements CRPM has obtained in medical applications, efficiency in some areas can be improved through digital twinning approaches. The digital twin has comprehensive capabilities and allows real-time monitoring that can be used to improve different phases of AM processes. In this study, areas that need further improvement in the process chain, such as management information that flows between different users and processes for design and setting up AM machines, will be discussed. The study will further indicate how these areas can benefit from available advanced technologies such as augmented reality (AR) technology and digital twin data management. Further implementation of this approach is expected to confirm the potential of easy self-learning approaches and managing data more effectively for improving the AM process chain.
Cosmic radiation exposure of airline crews in France over the period 2015–2019
Authors: Lestaevel P. , Huet C. , Lejeune V. , Moreno C. , Villagrasa C. , Feuardent J. , Trompier F.
Published: December 2023

Cosmic particle flux increases with latitude and altitude and is significantly higher on-board aircraft than at ground level. Furthermore, its intensity depends on solar activity and eruptions. Due to their professional activity, flight crews (FCs) may receive an annual dose of some millisieverts. Therefore, the European directive adopted in 1996 requires the aircraft operators to assess the dose. The effective dose is to be estimated using various experimental and calculation means. In France, it is carried out by the computerized system for flight assessment of exposure to cosmic radiation SIEVERTPN, which sends to SISERI, the national dose registry, the monthly effective dose of each crew member. The average annual effective dose of French FCs was 2.19 mSv in 2019, i.e. between the standard permissible limits set for the public and the limit set for occupationally exposed persons. The effective dose received by the most exposed French FCs increased during the period 2015–2019 and that could be due to the solar cycle effect, changes in the staff flight time or the aircraft model. It can also be noted that more technical flight crews (TFCs) received a dose greater than 5 mSv over the 2016 to 2019 period than commercial flight crew (CFCs). Our study indicates that the number of FCs having received a dose greater than 5 mSv also increased over the period 2016 to 2019. Some parameters, that may affect the assessment of the aircrew effective dose, are not considered in SIEVERTPN calculations, as for example the Forbush decreases and the location in the plane. Lastly, several factors lead us to expect a decrease in the doses received by French aircrew staff in the coming years, such as the peak activity of the 25th eleven-year solar cycle expected in July 2025. However, some unexpected events, as for instance the war in Ukraine, can alter this prediction.
Establishment of local diagnostic reference levels for breast cancer CT protocols in radiotherapy in a single Moroccan center
Authors: Nhila O. , Talbi M. , Youssoufi M.A. , El Mansouri M. , Tahiri Z. , Chakir E.M. , Azougagh M.
Published: December 2023

The objective of this study was to establish local diagnostic reference levels (LDRLs) for breast cancer computed tomography imaging in radiotherapy (CT-RT) at a single hospital in Morocco. Data were collected from 106 adult breast cancer patients aged between 33 and 78 yr during five months. Data were obtained using a Hitachi Supria 16-slice CT simulator at a regional oncology center in Morocco. CT-RT images are intended for 3D conformal radiotherapy treatment planning. Dose length product (DLP) and volumetric computed tomography dose index (CTDIvol) were evaluated by determining the 75th percentile as diagnostic reference levels for CT-RT breast cancer. LDRLs for CT-RT breast cancer have been determined in terms of DLP and CTDIvol, and they were 330.4 mGy.cm and 6.8 mGy, respectively. The DRLs were compared with other Europeans study. DRLs for this study were lower than those for the United Kingdom (UK), Croatia and Slovenia. The results of this study can be a reference for the establishment of local and national DRLs in Morocco and the optimization of CT-RT breast cancer procedures.
Requirement for diagnostic medical physicists in Vietnam
Authors: Nguyen T-Q. , Nguyen T-M. , Tran H-N.
Published: December 2023

This paper mentions the status of diagnostic medical physicists, estimating the lack of this work in Vietnam. The evaluation method is based on International Atomic Energy Agency documents and typical hospital models in Vietnam. In 2021, there were no diagnostic medical physicists. The roles and responsibilities of diagnostic medical physicists are currently performed by radiologists, biomedical engineers, and medical physicists in radiation oncology or nuclear medicine. This job is still a potential profession in Vietnam.
Analyzing the evolution of the artistic image of “Yang Yuhuan” from a feminist perspective through the lens of arts and cultural management
Authors: Yang Yanfei
Published: December 2023

Yang Yuhuan is a controversial consort from ancient China. From historical records to literary works and even contemporary film and television dramas, the image of Yang Yuhuan has been constantly reshaped. However, in the fields of stage drama and film and television works, there has been relatively limited scholarly research on her image, with even fewer touching on arts and cultural management. This paper adopts a feminist perspective to analyze the evolution of Yang Yuhuan’s image over different periods, taking her drama and film portrayals as the study subjects. The aim is to explore how, in the current societal context, one might enrich the image of Yang Yuhuan from the standpoint of arts management. Through this research, the author observes that the underlying representation of Yang Yuhuan is that of a beautiful and nation-damaging favored consort. Notably, such an image is not merely the result of personal choice but a collective product of power and knowledge. In recent years, China’s art market has seen abundant creative representations of Yang Yuhuan, but innovations concerning her image have been scant, largely adhering to its original mold. This does not align with contemporary societal and cultural norms and fails to meet audience demands. Therefore, to further diversify the image of Yang Yuhuan, creators should transcend her traditional objectified portrayal, emphasize the unique political aspects of her love story with Emperor Li Longji, reconsider the notion that “a woman can cause the downfall of a nation,” and collaboratively innovate her image through arts management.
Based on Japan’s Indo-Pacific strategy, explore the development path of China-Japan relations
Authors: Pan Siyu , Wang Weitao , Ye Qianhong
Published: December 2023

Japan was the first country to propose the concept of “Indo-Pacific strategy” and was also a staunch supporter and active promoter of it. The formation of Japan’s Indo-Pacific strategy has gone through four stages of evolution: initial appearance, initial formation, extension, and all-round development, and has continuously promoted the development of the Indo-Pacific strategy in a more institutionalized and mature direction from many fields, It has formed a strategic layout in many fields such as comprehensive value sharing, economic and trade competition, maritime security, and multilateral mechanisms. Under the influence of the increasingly fierce competition between China and the US and the policy of putting the United States first, Japan has changed from a proposer of the Indo-Pacific strategy to a promoter, and the Japanese government actively seeks Japan and the United States to jointly dominate the Indo-Pacific economic security order. The accession of the United States has made international relations in the Indo-Pacific region more complex and changeable, and it will have a significant impact on China’s national interests and strategic orientation in the Indo-Pacific area. Sorting out the Japanese Indo-Pacific strategy will help explain the mechanism, rationale, and implementation effect of Japan’s policy choices under the China-US competition, and can also provide a reference for China’s decision-making.
Philippine hedging strategy from the perspective of neoclassical realism
Authors: Liu Yutong
Published: December 2023

As the main diplomatic strategy of the Philippines towards China, the hedging strategy has been practiced for a long time. In recent years, with the acceleration of Sino-American Geopolitical Competition, as well as the transfer of power in the Asia Pacific region, Southeast Asian countries are facing new strategic decision-making pressure. From the perspective of neoclassical realism, systemic pressure is transmitted through internal factors within a country, thereby determining diplomatic strategy. For the Philippines, the systemic pressure brought about by the Sino-U.S. competition serves as the independent variable, while the domestic security and economic development needs of the Philippines serve as intervention variables, jointly influencing diplomatic strategy. Through analysis, it can be seen that in the new stage of the Sino-U.S. competition, the hedging strategy of the Philippines has changed. During the Duterte period, the Philippines implemented a friendly strategy towards China of “military proximity to the United States and economic contact with China”. After Marcos Jr. came to power, there was a trend of partial checks and balances in the Philippines’ policy toward China. Overall, it still shows a major country balance orientation and will maintain this characteristic in the short term.
The impact of American Philippine economic policy on Philippine modern economy during the Cold War
Authors: Li Yixuan
Published: December 2023

As an important country in Southeast Asia, the Philippines has repeatedly occupied an important geographical position and had an important geographical and political position during the Cold War. Since the Cold War, the relationship between the United States and the Philippines has been very close, and the influence of the United States on the Philippines is self-evident. Therefore, studying the political influence of the United States on Philippine economic policy during the Cold War has important theoretical and practical significance. Starting from the economic policy adopted by the United States in the Philippines, this paper analyzes the economic assistance methods of the United States to the Philippines and its political influence on the Philippines and explains why the United States exercises neocolonial control over the Philippines from two aspects. This article argues that the United States has influenced the Philippine economy in a neocolonial way in an attempt to expand the political influence and sphere of influence of the United States itself.
The Contrast between Japanese and Chinese Gardens – Taking Humble Administrator’s Garden in Suzhou and Katsura Imperial Villa in Kyoto as Examples
Authors: He Zhen
Published: December 2023

Garden culture has evolved through thousands of years to create its own distinctive features in both China and Japan. Chinese culture also had a major influence on Japanese culture, which is seen in garden culture. Both the Humble Administrator’s Garden and the Katsura Imperial Villa were built during the same eras, the Ming Dynasty and the Edo era, and they are considered to be the greatest examples of Japanese and Chinese garden architecture. The garden design, water features, and rock elements of the Humble Administrator’s Garden and the Katsura Imperial Villa are thoroughly compared in this study to highlight their commonalities and differences. It explores the factors behind these distinctions, encompassing the design and aesthetic concepts of the two countries, while considering the influence of cultural, economic, and natural factors. Additionally, the research uncovers key findings, shedding light on the distinctions between these two gardens and the influential factors, including cultural, economic, and natural influences, shaping their unique characteristics. The study delves into historical, geographical, and cultural influences, unveiling the distinct preferences and philosophies of Chinese and Japanese garden aesthetics. Ultimately, this research extends readers’ comprehension of Chinese and Japanese garden art and culture, fostering positive cross-cultural understanding and communication between the two nations. Through comparison and analysis, readers gain a deeper understanding of the underlying ideologies and aesthetics of these two cultures, promoting greater exchange and mutual enrichment in the realm of Sino-Japanese garden art.
Impact of virtual identities on social media on women’s self-esteem
Authors: Liu Yunjie
Published: December 2023

The present study focuses on the influence of social media (SM) on an individual’s self-esteem and self-evaluation. The construction of virtual identities in cyberspace affect individual’s mental health. The article introduces the concepts of self-esteem and self-evaluation from a psychological perspective and explores the multifaceted factors that influence the formation of virtual identities on social media. Previous research suggests that prolonged exposure to idealized images on SM may lead to dissatisfaction and mood swings in individuals, especially among young women. This phenomenon may be due in part to the fact that social media allows users to edit and present an idealized self-image. The article highlights the fact that the association between social media, self-esteem and self-evaluation is a complex and worthwhile area of in-depth research, which not only has important implications for an individual’s psychological well-being, but also involves a number of important issues in the fields of social psychology and psychological science.