Formation Process Research Articles

Absence of female preference and the origin of a unisexual species, the Amazon molly (Poecilia formosa)

AbstractThe role of hybridization as a formative process in evolution has received much attention in the past few decades. A particularly fascinating outcome of hybrid speciation is the formation of asexual hybrid species. The Amazon molly (Poecilia formosa) is such a hybrid and originated from a P. mexicana mother and a P. latipinna father. Consequently, a heterospecific mating must have occurred leading to the Amazon molly, indicating a breakdown of any potential prezygotic isolation between parental species. Here we studied the female mate preferences of extant P. mexicana and P. latipinna from several populations using standard binary choice tests with males of both sexual species that were matched for size. Poecilia mexicana and P. latipinna can be crossed in the lab, however, the offspring are not asexual, but sexual F1s. In our study, we generated F1s and tested their mating preferences with sexual males of both P. mexicana and P. latipinna against F1 males. Overall, our results show that in extant P. mexicana and P. latipinna no female preference for conspecific males was detectable. Consequently, heterospecific matings are possible and not hindered by any apparent behavioral prezygotic isolation. If female preferences in these species were comparable around the time the Amazon molly originated as a hybrid species ca. 100,000 years ago, matings leading to hybrids would be very likely. F1 females also have no discernable mating preferences for either sexual males or F1 males. Such lack of prezygotic behavioral isolation could potentially lead to F2 individuals, backcrosses, and introgression.

The influence of an innovative antibacterial drug of the thiadiazinone class on the virulence factors of bacteria of the phylum Pseudomonadota, which chronically infect patients with cystic fibrosis

Introduction. Infections of the lower respiratory tract by bacteria of the Pseudomonadota phylum: Pseudomonas aeruginosa, Burkholderia spp., Achromobacter spp. are critical to the quality and life expectancy of patients with cystic fibrosis (CF). When the infection is chronic, eradication of bacteria with existing antibacterial drugs is practically impossible. To explore alternative drugs, trials are needed on bacteria isolated from CF patients and characterized using genomic approaches. The objective of our study was a comparative analysis of virulence factors of 6 isolates of bacteria of the Pseudomonadota phylum and testing the efficacy of the innovative drug Fluorothiazinone (FT) in suppressing the pathogenicity of bacteria in vitro. Materials and methods. Isolates of A. ruhlandii ST36, A. xylosoxidans ST555, B. cepacia ST2140, B. gladioli ST2141, P. aeruginosa ST859 and ST198 were examined using whole-genome sequencing and bioinformatics analysis to search for resistance and virulence determinants. The FT drug was tested for its effect on bacteria in in vitro experiments on cytotoxicity on HeLa cells, motility and biofilm formation. Results. Genomic studies have confirmed the arsenal of resistance determinants, especially the efflux systems of bacteria isolated from patients with CF, and the diversity of virulence factors, among which we identified factors in the categories of motility, signals of quorum-sensing systems, secretion systems, exotoxins, as the most essential for the adaptation of bacteria to conditions of the lower respiratory tract. In vitro tests of the FT drug showed its effectiveness in suppressing cytotoxicity (2.6–4.0 times), motility (2.0–3.6 times) and the process of biofilm formation (2.0–7.7 times). Conclusion. For the first time, the effectiveness of the innovative antibacterial drug Fluorothiazinone has been shown against bacteria of the Pseudomonadota phylum, isolated from chronically infected patients with CF, with the described potential of virulence factors.

Designed Additive to Regulated Crystallization for High Performance Perovskite Solar Cell.

It is a crucial role for enhancing the power conversion efficiency (PCE) of perovskite solar cells (PSCs) to prepare high-quality perovskite films, which can be achieved by delaying the crystallization of perovskite film. Hence, we designed difluoroacetic anhydride (DFA) as an additive to regulating crystallization process thus reducing defect formation during perovskite film formation. It was found DFA reacts with DMSO by forming two molecules, difluoroacetate thioether ester (DTE) and difluoroacetic acid (DA). The strong bonding DTE·PbI2 and DA·PbI2 retard perovskite crystallization process for high-quality film formation, which was monitored through in situ UV-vis and PL tests. By using DFA additives, we prepared perovskite films with high-quality and low defects. Finally, a champion PCE of 25.28% was achieved with excellent environmental stability, which retained 95.75% of the initial PCE after 1152 h at 25 °C under 25% RH.

Obtaining and studying the composition, structure and properties of nanophases and nanolayers of CoSi2

ABSTRACT The processes of formation of a thin film of cobalt disilicide on the silicon surface due to the formation of several nuclei of atomic thickness on the surface of the silicon substrate are presented. To create these structures, the ion implantation method was used. The dependence of the depth of penetration of ions into the substrate during ion implantation on temperature and ion dose was determined. In the case of implantation of Co+ ions into Si at room temperature silicon uniformly combines with Co atoms at a depth of 3.5–4 nm, the Co concentration in these layers is 45–50 at. %. Co has been shown to form chemical bonds with Si atoms in the sample containing 40–45 atomic % of Co. When implanting Co+ into Si at 600 K, it was found that the depth of the same added layer is 2.5–3 nm, and CCo forming bonds with Si atoms increases to 85–90%.

Multiple sources of water preserved in impact glasses from Chang'e-5 lunar soil.

The existence of molecular H2O and evolution of solar wind-derived water on the lunar surface remain controversial. We report that large amounts of OH and molecular H2O related to solar wind and other multiple sources are preserved in impact glasses from Chang'e-5 (CE5) lunar soil based on reflectance infrared spectroscopy and nanoscale secondary ion mass spectrometry analyses. The estimated water content contributed by impact glasses to CE5 lunar soil was ~72 ppm, including molecular H2O of up to 15 to 25 ppm. Our studies revealed that impact glasses are the main carrier of molecular H2O in lunar soils. Moreover, water in CE5 impact glasses provides a record of complex formation processes and multiple water sources, including water derived from solar wind, deposited by water-bearing meteorites/micrometeorites, and inherited from lunar indigenous water. Our study provides a better understanding of the evolution of surficial water on airless bodies and identifies potential source and storage pathways for water in the terrestrial planets.

Phantom Attractors in a Single-Degree-of-Freedom Smooth System Under Additive Stochastic Excitation

Phantom attractors in nonlinear systems under additive stochastic excitation have been recently discovered. This paper uncovers the existence of phantom attractors in a single-degree-of-freedom smooth nonlinear equation, which characterizes the vibration of an inextensible beam subjected to lateral stochastic excitation. It also elucidates that the stochastic averaging method, in this context, may lead to qualitatively erroneous probability density functions, identified as one of the reasons why these attractors were previously overlooked. The study then proceeds to analyze the formation process of the phantom attractor and the critical noise intensity associated with it. Subsequently, the key nonlinear term related to the emergence of phantom attractors is identified by observing whether the system still exhibits phantom attractors after the corresponding nonlinear terms are removed. It is revealed that in this system, the presence of phantom attractors is closely linked to the inertia nonlinearity of the hardening type. The system investigated in this paper is simpler compared to previously identified systems capable of generating phantom attractors. This simplicity aids in facilitating research focused on unraveling the general principles behind the formation of phantom attractors.

Application of language tests in university education. Evaluation of a formative process.

La aplicación de pruebas lingüísticas en contextos reales es una competencia fundamental que los estudiantes de los grados en Logopedia y en Educación Primaria deben aprender. El objetivo de esta investigación consiste en comprender y evaluar el proyecto formativo universitario llevado a cabo para que los estudiantes aprendan a aplicar pruebas lingüísticas. El proyecto se divide en tres fases: los estudiantes graban la aplicación de las pruebas lingüísticas, los profesores enseñan el proceso de evaluación, y otros estudiantes analizan y corrigen las pruebas grabadas. Un grupo de 200 participantes completa un cuestionario que incluye preguntas sobre las dificultades y desafíos encontrados y la idoneidad de la práctica. Se valora por separado la enseñanza de pruebas estandarizadas/baterías y la enseñanza de protocolos/registros. Los resultados sugieren que las actividades propuestas son apropiadas. Aunque no se observan diferencias significativas entre los grupos en cuatro variables, surgen disparidades en la comprensión de los vídeos, la toma de notas en las hojas de registro, la elaboración de conclusiones y la redacción de informes. Lo que significa que esta investigación es útil para aquellos docentes que estén interesados en llevar a cabo proyectos formativos con aplicación práctica en el aula y poder así generalizar el proceso formativo a otras universidades.

Three-Body Binary Formation in Clusters: Analytical Theory

Abstract Binary formation in clusters through triple encounters between three unbound stars, ‘three-body’ binary formation, is one of the main dynamical formation processes of binary systems in dense environments. In this paper, we use an analytical probabilistic approach to study the process for the equal mass case and calculate a probability distribution for the orbital parameters of three-body-formed binaries, as well as their formation rate. For the first time, we give closed-form analytical expressions to the full orbital parameter distribution, accounting for both energy and angular momentum conservation. This calculation relies on the sensitive dependence of the outcomes of three-body scatterings on the initial conditions: here we compute the rate of three-body binaries from ergodic interactions, which allow for an analytical derivation of the distribution of orbital parameters of the binaries thus created. We find that soft binaries are highly favoured in this process and that these binaries have a super-thermal eccentricity distribution, while the few hard three-body binaries have an eccentricity distribution much closer to thermal. The analytical results predict and reproduce simulation results of three-body scattering experiments in the literature well.

Electrochemically produced nano-TiO2-coated SiC membranes for photocatalytic water treatment: Preparation, characterization, and hydroxyl radical formation

ABSTRACT Photocatalytically active ceramic flat sheet membranes based on a nanostructured titanium dioxide (TiO2) coating were produced for photocatalytic water treatment. The nano-TiO2 layer was produced by a novel combination of magnetron sputtering of a thin titanium layer on silicon carbide (SiC) membranes, followed by electrochemical oxidation (anodization) and subsequent heat treatment. Characterization by Raman spectra and field emission scanning electron microscopy proved the presence of a nanostructured anatase layer on the membranes. The influence of the titanium layer thickness on the TiO2 formation process and the photocatalytic properties were investigated using anodization curves, by using cyclovoltammetry measurements, and by quantifying the generated hydroxyl radicals (OH•) under UV-A irradiation in water. Promising photocatalytic activity and permeability of the nano-TiO2-coated membranes could be demonstrated. A titanium layer of at least 2 μm was necessary for significant photocatalytic effects. The membrane sample with a 10 μm Ti/TiO2 layer had the highest photocatalytic activity showing a formation rate of 1.26 × 10−6 mmol OH• s−1. Furthermore, the membranes were tested several times, and a decrease in radical formation was observed. Assuming that these can be attributed to adsorption processes of the reactants on the TiO2 surface, initial experiments were carried out to reactivate the photocatalyzer.

Heart-on-a-Chip Model of Epicardial-Myocardial Interaction in Ischemia Reperfusion Injury.

Epicardial cells (EPIs) form the outer layer of the heart and play an important role in development and disease. Current heart-on-a-chip platforms still do not fully mimic the native cardiac environment due to the absence of relevant cell types, such as EPIs. Here, using the Biowire II platform, engineered cardiac tissues with an epicardial outer layer and inner myocardial structure are constructed, and an image analysis approach is developed to track the EPI cell migration in a beating myocardial environment. Functional properties of EPI cardiac tissues improve over two weeks in culture. In conditions mimicking ischemia reperfusion injury (IRI), the EPI cardiac tissues experience less cell death and a lower impact on functional properties. EPI cell coverage is significantly reduced and more diffuse under normoxic conditions compared to the post-IRI conditions. Upon IRI, migration of EPI cells into the cardiac tissue interior is observed, with contributions to alpha smooth muscle actin positive cell population. Altogether, a novel heart-on-a-chip model is designed toincorporate EPIs through a formation process that mimics cardiac development, and this work demonstrates that EPI cardiac tissues respond to injury differently than epicardium-free controls, highlighting the importance of including EPIs in heart-on-a-chip constructs that aim to accurately mimic the cardiac environment.

Catalyst-regulated conversion of p-phenylenediamine-based carbon dots from red to deep-blue emission

Deep-blue emission (＜450 nm) is significant in high-density information storage, solid-state lighting, and vivid displays. However, the carbon dots (CDs) obtained from p-phenylenediamine (pPD) have only red fluorescence, which greatly limits the application and development of pPD-based CDs. As we all know, a catalyst is a substance that can change the rate and pathway of a chemical reaction. Herein, we designed to add a catalyst to realize the conversion of pPD-based CDs from red to deep-blue fluorescence. The emission peak of obtained deep-blue CDs was 440 nm, and the full-width at half-maximum (FWHM) was only 58 nm, with a high color purity. In addition, through in-depth analysis of microstructure and photoluminescence (PL) properties, it is found that the decrease of the sp2-conjugated domain and the graphite N content and the increase in pyridinic N content were the main reasons for the blue shift of the spectra. Based on this, the formation process and mechanism of red and deep-blue CDs were further elucidated. This work not only efficiently realized the design of the deep-blue CDs but also provided a new idea for the luminescence regulation of CDs without changing the raw materials and reaction conditions.

A computational model of the effects of borrower default on the stability of P2P lending platforms

AbstractPeer-to-peer (P2P) lending has attracted scholarly attention because of its economic significance and potential to democratize access to finance. However, P2P lending platforms face many challenges and failures that we need to understand more clearly. We build a computational model to study how borrower default affects P2P platform lending. We show that borrower default disrupts the P2P network formation process and undermines platform stability. Moreover, we find that defaults increase the inequality in accessing funding and provide a rationale for using curation rules, widely used in P2P platforms, in contrast to P2P insurance, which fosters cascading defaults. We also address a new trend in P2P lending platforms in which large companies (institutional investors) play an increasingly important role. We find that the presence of large companies creates a denser network (more loans) but generates a trade-off between making the platform more resilient to cascading defaults and more dependent on specific players. Overall, we explain how borrower defaults affect platform stability and what makes a platform vulnerable, threatening its survival. We discuss research and managerial insights into platform stability and the economic effect of P2P lending platforms.

Infertility psychological distress in women undergoing assisted reproductive treatment: A grounded theory study.

While there exists an ample body of research in international contexts focused on the characterization and quantification of infertility psychological distress, the level of scholarly scrutiny directed towards this phenomenon within the context of China remains scant. To investigate the formation and developmental processes of psychological distress associated with infertility and infertility treatment among women within the Chinese cultural context and to construct a theoretical framework that elucidates this phenomenon. Qualitative approach with grounded theory methodology. This study was conducted within the reproductive medicine department of a tertiary-level hospital located in central China from May to August 2023. Twenty-seven women who experienced infertility and underwent assisted reproductive treatment (ART) were interviewed. The interview sessions spanned durations ranging from 20 min to 1 h and 35 min. Data analysis included open coding, axial coding and selective coding. The study is reported using the COREQ checklist. The infertility psychological distress experienced by women undergoing ART is a socially constructed phenomenon influenced by a dynamic interplay of forces that construct and conciliate it. The formation and progression of infertility psychological distress are rooted in the process of self-construction. A Middle-Ranged Theory titled 'self-reconstruction under the dome of infertility and infertility treatment' (SUDIT theory) was developed to explain this phenomenon. Within this framework, infertility psychological distress manifests across three distinct phases under the gambling ofthe constructive force and conciliative force: (1) distress of disrupting the former self; (2) distress linked to the struggling present self; and (3) the renewed-self harmonized with distress. It is imperative for healthcare professionals and policymakers to acknowledge the socially constructed nature of infertility psychological distress, and proactively implement measures aimed at ameliorating it. No patient or public contribution.

A study of two young multipolar planetary nebulae: Hen 2-73 and Hen 2-96

We perform an infrared (IR) spectral and visible morphological study of two young planetary nebulae (YPNe) Hen 2-73 and Hen 2-96 using archival Spitzer Space Telescope and Hubble Space Telescope (HST) observations to understand their dust properties and nebular structures. High-resolution HST images of these nebulae show several bipolar lobes and ionised tori in the central regions of both objects. The presence of these multi-lobe structures suggests that the formation process of these nebulae is complex. To search for a possible link between the central sources and multipolar appearances of these objects, the Transiting Exoplanet Survey Satellite (TESS) observations are used to examine whether their central stars (CSs) exhibit periodic photometric variations. In the TESS observations, the CS light curve of Hen 2-96 shows a photometric variation with a period of 2.23 hr. The IR spectra of these two YPNe suggest that the nebulae have mixed dust environments, which are associated with the presence of dense tori created by central binary interactions in these objects. Two three-dimensional models are constructed to study the complex nebular structures of the YPNe. These simulations suggest that the number of multipolar YPNe may be larger than observed. In addition, we analyse the spectral energy distributions of these nebulae to study their gas, dust, and photospheric components.

The relationship between the cutting-edge, tool wear, and chip formation during Inconel 718 dry cutting

AbstractThis study comprehensively addresses the machining of nickel alloys, focusing its attention on crucial aspects related to chip formation and tool wear. Detailed characterization of the morphology and the chip formation process was performed by analyzing parameters such as chip segmentation ratio and variables such as shear band thickness and strain rate. Additionally, a numerical model was used to quantify stresses and temperatures at the tool/chip interface and to evaluate damage, thus contributing to the understanding of the development of chip formation. A transition in chip shapes as the toothing increases is highlighted, evidenced by segmentation ratio values below 0.5, indicative of the presence of discontinuous chips. The increase in cutting-edge radius is associated with a gradual increase in the compression ratio, indicating a higher plastic energy requirement in chip formation. Numerical simulations support this theory of failure. A significant correlation of 80% was identified between flank wear and the increase in shear force oscillation amplitude, indicating that flank wear contributes to system vibration. It is also noted that the adiabatic shear bands (ASB) are narrow, revealing a marked plastic deformation in the primary shear zone. Consequently, the remarkable incidence of wear with cutting parameters on chip formation is demonstrated, affecting the cutting force amplitude and, hence, the workpiece topography.

Clinical and Ultrasound Efficacy of Topical Hypertonic Cream (Jovita Osmocell®) in the Treatment of Cellulite: A Prospective, Monocentric, Double-Blind, Placebo-Controlled Study

Background and Objectives: Cellulite, or edemato-fibro-sclerotic panniculopathy (EFP), is characterized by dermal and hypodermal changes leading to adipose tissue accumulation and compromised venous circulation. This study investigates the efficacy of a hypertonic cream containing concentrated sodium chloride (Jovita Osmocell®) in addressing water retention and structural alterations in adipose tissue, aiming to interrupt the cellulite formation process. Materials and Methods: A 12-week, prospective, monocentric, double-blind, placebo-controlled study enrolled 30 female subjects with grade II or III cellulite. Patients were randomized to receive hypertonic cream or a placebo. Thigh circumference, ultrasound evaluations, and standardized photographs were collected at baseline, intermediate, and endpoint visits. Adverse events were monitored. Results: After 84 days, the hypertonic cream group exhibited a significant reduction in thigh circumference compared to the placebo group (p = 0.0037). B-mode ultrasound examinations revealed significant changes in the parameters studied, such as the thickness of the subcutaneous tissue. No statistically significant changes were noticed in the placebo group. Volunteers reported the investigational product’s pleasantness and good anti-cellulite activity, with no reported adverse events. Conclusions: The hypertonic cream demonstrated efficacy in reducing thigh circumference, addressing water retention and structural alterations in adipose tissue. The proposed mechanism involves osmosis, releasing accumulated fluids between fat cells, supporting drainage, and reducing inflammation. This study supports the efficacy and safety of hypertonic sodium chloride emulsions in cellulite treatment and confirms safety and user satisfaction.

Simulating the seeder–feeder impacts on cloud ice and precipitation over the Alps

Abstract. The ice phase impacts many cloud properties as well as cloud lifetime. Ice particles that sediment into a lower cloud from an upper cloud (external seeder–feeder process) or into the mixed-phase region of a deep cloud from cirrus levels (internal seeder–feeder process) can influence the ice phase of the lower cloud, amplify cloud glaciation and enhance surface precipitation. Recently, numerical weather prediction modeling studies have aimed at representing the ice crystal number concentration in mixed-phase clouds more accurately by including secondary ice formation processes. The increase in the ice crystal number concentration can impact the number of ice particles that sediment into the lower cloud and alter its composition and precipitation formation. In the Swiss Alps, the orography permits the formation of orographic clouds, making it ideal for studying the occurrence of multi-layered clouds and the seeder–feeder process. We present results from a case study on 18 May 2016, showing the occurrence frequency of multi-layered clouds and the seeder–feeder process. About half of all observed clouds were categorized as multi-layered, and the external seeder–feeder process occurred in 10 % of these clouds. Between cloud layers, ≈60 % of the ice particle mass was lost due to sublimation or melting. The external seeder–feeder process was found to be more important than the internal seeder–feeder process with regard to the impact on precipitation. In the case where the external seeder–feeder process was inhibited, the average surface precipitation and riming rate over the domain were both reduced by 8.5 % and 3.9 %, respectively. When ice–graupel collisions were allowed, further large reductions were seen in the liquid water fraction and riming rate. Inhibiting the internal seeder–feeder process enhanced the liquid water fraction by 6 % compared to a reduction of 5.8 % in the cloud condensate, therefore pointing towards the de-amplification in cloud glaciation and a reduction in surface precipitation. Adding to the observational evidence of frequent seeder–feeder situations, at least over Switzerland, our study highlights the extensive influence of sedimenting ice particles on the properties of feeder clouds as well as on precipitation formation.

Exploring secondary aerosol formation associated with elemental carbon in the lower free troposphere

The variability of element carbon (EC) mixed with secondary species significantly complicates the assessment of its environmental impact, reflecting the complexity and diversity of EC-containing particles' composition and morphology during their ascent and regional transport. While the catalytic role of EC in secondary aerosol formation is recognized, the effects of heterogeneous chemistry on secondary species formation within diverse EC particle types are not thoroughly understood, particularly in the troposphere. Alpine sites offer a prime environment to explore EC properties post-transport from the ground to the free troposphere. Consequently, we conducted a comprehensive study on the genesis of secondary aerosols in EC-containing particles at Mt. Hua (altitude: 2069 m) from 1 May to 10 July, using a single particle aerosol mass spectrometer (SPAMS). Our analysis identified six major EC particle types, with EC-K, EC-SN, and EC-NaK particles accounting for 27.6 %, 27.0 %, and 19.6 % of the EC particle population, respectively. The concentration-weighted trajectory (CWT) indicated that the lower free troposphere over Mt. Hua is significantly affected by anthropogenic emissions at ground-level, predominantly from northwestern and eastern China. Atmospheric interactions are crucial in generating high sulfate levels in EC-SN and EC-OC particles (> 70 %) and notable nitrate levels in EC-K, EC-BB, and EC-Fe particles (> 80 %). The observed high chloride content in EC-OC particles (56 ± 32 %) might enhance chlorine's reactivity with organic compounds via heterogeneous reactions within the troposphere. Distinct diurnal cycles for sulfate and nitrate are mainly driven by varying transport dynamics and formation processes, showing minimal dependency on EC particle types. Enhanced nocturnal oxalate conversion in EC-Fe particles is likely due to the aqueous oxidation of precursors, with Fe-catalyzed Fenton reactions enhancing OH radical production. This investigation provides critical insights into EC's role in secondary aerosol development during its transport in the lower free troposphere.

APPROVAL OF FORMATION OF PROFESSIONAL COMPETENCE OF FUTURE OPERATORS IN INFORMATION PROCESSING AND SOFTWARE

The article is devoted to the problem of researching the effectiveness of the process of forming the professional competence of future information processing and software operators in the process of professional training. It was found that the system of training future specialists in the process of professional training is aimed at ensuring their readiness for professional activity, taking into account all components of the educational process of the educational institution. It was clarified that the important factors of the problem of the formation of professional competence of future specialists in the process of professional training are inadequate readiness for professional activity and the appropriate level of their professional competence for such activity. It was revealed that the process of formation of professional competence of individuals for professional activity is influenced by the following factors: transformation of the content of training of future operators in information processing and software in professional (vocational and technical) education institutions; the prestige of the profession and its social significance; professional development and development of the personality of future specialists; acquisition of practical experience by students of education regarding the implementation of innovative technologies and project activities; purposeful mastery of professional skill and specialty; the formation of a culture of mastery and the readiness of qualified specialists for professional activity. It is specified that the formation of professional competence of future specialists in the process of professional training is oriented towards: purposeful formation of a complete system of professional competences in the process of professional training; development of motivational potential; enrichment of the development of individual and professional qualities, formation of self-assertion, improvement of personal and professional assets, acquisition of one's own style of work; accumulation of experience in professional skills for effective performance of professional activities, improvement of professional abilities and skills for further self-actualization, self-improvement of professional activities, development of quick adaptation to full-fledged future activities; improvement of assets of creative and scientific research, enabling professional self-development in professional activity. The study of the continuity of the development of future specialists to professional activity requires further development.

In situ build surface topography determination in electron beam powder bed fusion

AbstractElectron optical imaging is the most promising process monitoring method in electron beam powder bed fusion. State of the art in modern machines is the installation of a single detector in the top center of the build chamber. Exemplary applications are the reconstruction of digital twins of manufactured parts to compare their dimensional accuracy or analysing the top surface of each layer to identify surface features like pores or material transport. Multi-detector systems are currently under research and have shown great potential in reconstructing the surface topography in situ. A recently developed ray tracing model, describing the image formation process, allows to formulate design guide lines for multi-detector systems and provides a method for the computation of the normal vector field of the build surface. This work utilizes the recent progress and presents a newly developed four-detector system and an updated computation chain, which enable build surface topography reconstruction in situ in every layer of a build process. The computation chain contains a normal integration algorithm, which employs Tikhonov regularization to cope with measurement irregularities. The integration method is validated with ex situ measured as-built surfaces. Additionally, first applications are demonstrated and connections to process parameter changes illustrated.