Shape Components Research Articles

The interaction of factors in constructing English learning motivation of China’s government-sponsored overseas academic visiting candidates on an official preparatory program

The present study investigates the English learning motivation of China’s government-sponsored overseas academic visiting candidates on an official intensive English preparatory program. A structural equation model (SEM) analysis was conducted on the results of a 33-item questionnaire survey taken by 632 such candidates, most of whom were university academics. By establishing a SEM model for the general sample and four sub-models for its sub-samples, the study delineates the complex interaction of the components in shaping this population’s English learning motivation against the backdrop of China’s grand socio-educational ambition. It also reveals some nuanced differences in the path coefficients in this motivational complex within each of its two sub-sample sets: the candidates with humanities and social science backgrounds vs. those with science backgrounds and the candidates from an institution or program on China’s Double First Class initiative vs. those not. These research findings may help a better understanding of the English learning ecology in today’s China. Theoretically, this study reinforces the usefulness of the prevailing L2 Motivational Self System framework while at the same time accentuating its socio-contextual variance; it also illuminates the future direction pertaining to the application of the Complex Dynamic Systems theory.

Surface characteristic of Ti-6Al-4V alloy fabricated by Electron Beam Melting prepared by different surface post treatments

Metal additive manufacturing (AM) is a technique in constant growth that offers freedom in design in the production of complex shape components. However, it is well documented that most types of material failures in the AM parts are very sensitive to their surface properties. Hence, in this work, some surface post-treatments such as grinding, drag finishing and Surface Mechanical Treatment (SMT) are used as post-treatment processes to improve the performance of Ti-6Al-4V samples fabricated by the Electron Beam Melting technique. The influences of different post-treatment were investigated on the surface properties. The outcomes demonstrated that the SMT has- the highest efficiency in the surface treatment and could reduce surface roughness, increase hardness and improve wettability. This work demonstrates the potential of SMT to achieve favourable surface properties of AM metallic components.

Nanoporous carbon@CoFe2O4 nanocomposite as a green absorbent for the adsorptive removal of Hg(ii) from aqueous solutions

Abstract To address the harmful pollutants found in heavy metals and agricultural waste, researchers have worked on creating various materials that can capture these pollutants. They have experimented with altering the shape, size, structure, surface properties, and bioactive components of these materials. This study aims to improve the effectiveness of materials used for adsorption, focusing on the combination of cobalt spinal ferrite (CoFe2O4) and nanoporous carbon (NC) obtained from discarded palm kernel shells with the aim of Hg(ii) removal. The composite formed by the hydrothermal method was characterized thoroughly with morphological, structural, functional, pore sizes, thermal analysis, and magnetization analysis. Adsorption experiments were conducted under optimal conditions with a mass of 0.3 g, a concentration of 30 mg·L−1 of Hg(ii), and a pH of 3. The aim was to adsorb Hg(ii) ions from aqueous solutions. The analysis of kinetic studies using the Freundlich model revealed that it provided the most accurate fit for the adsorption isotherm. This model indicated a maximum Hg(ii) adsorption efficiency of 232.56 mg·g−1. Additionally, the thermodynamic measurements indicate that the adsorption is a spontaneous, favorable, and endothermic process. Likewise, we assessed how well the NC@CoFe2O4 nanocomposite could absorb Hg(ii) ions in actual condensate samples from the oil and gas industry. The results demonstrated a 93% recovery rate for Hg(ii) ions in wastewater. According to the findings, the NC@CoFe2O4 nanocomposite synthesized appears to be a strong contender for wastewater treatment and, at the same time, the prepared nanocomposite’s effectiveness, affordability, and non-toxic nature support the potential applications.

Machining of additively manufactured alloy 718 in as-built and heat-treated condition: surface integrity and cutting tool wear

AbstractAdditive manufacturing (AM) using powder bed fusion is becoming a mature technology that offers great possibilities and design freedom for manufacturing of near net shape components. However, for many gas turbine and aerospace applications, machining is still required, which motivates further research on the machinability and work piece integrity of additive-manufactured superalloys. In this work, turning tests have been performed on components made with both Powder Bed Fusion for Laser Beam (PBF-LB) and Electron Beam (PBF-EB) in as-built and heat-treated conditions. The two AM processes and the respective heat-treatments have generated different microstructural features that have a great impact on both the tool wear and the work piece surface integrity. The results show that the PBF-EB components have relatively lower geometrical accuracy, a rough surface topography, a coarse microstructure with hard precipitates and low residual stresses after printing. Turning of the PBF-EB material results in high cutting tool wear, which induces moderate tensile surface stresses that are balanced by deep compressive stresses and a superficial deformed surface that is greater for the heat-treated material. In comparison, the PBF-LB components have a higher geometrical accuracy, a relatively smooth topography and a fine microstructure, but with high tensile stresses after printing. Machining of PBF-LB material resulted in higher tool wear for the heat-treated material, increase of 49%, and significantly higher tensile surface stresses followed by shallower compressive stresses below the surface compared to the PBF-EB materials, but with no superficially deformed surface. It is further observed an 87% higher tool wear for PBF-EB in as-built condition and 43% in the heat-treated condition compared to the PBF-LB material. These results show that the selection of cutting tools and cutting settings are critical, which requires the development of suitable machining parameters that are designed for the microstructure of the material.

Simultaneous improvement of strength and ductility of laser additively produced Ti6Al4V by adding tantalum

Laser additive manufacturing (LAM) technique can efficiently fabricate Ti6Al4V components of complex shapes, but often show poor mechanical properties. In this study, tantalum (Ta) was added into Ti6Al4V as an alloying element to improve the overall mechanical performance using a laser cladding system. It was found that Ti6Al4V–4Ta (corresponding to 4 wt% Ta) exhibited excellent mechanical performance with the yield stress of 956 MPa, ultimate tensile strength of 1042 MPa and the elongation of 10.8 %, meeting the ISO 7209 requirements for titanium and titanium alloys. The synergistic improvement of strength-ductility of Ti6Al4V–4Ta was attributed to the microstructure refinement, weakened α-variants selection, Ta solid solution, modified dislocation density and β phase content. Further quantitative analysis demonstrated that the strength increase was mainly contributed from the additional grain boundary, solid solution and dislocation induced by Ta elemental alloying. This study established Ta elemental alloying as an effective method to simultaneously enhance the strength and ductility of Ti6Al4V alloy using LAM technology.

Asymmetric morphological filter for roughness evaluation of multifunctional surfaces

The scope of multifunctional surfaces in mechanical engineering and instrumentation is constantly expanding. Examples are products with multilayer coatings, products made of composite materials or using additive manufacturing technologies. A feature of multifunctional surfaces is two levels of texture with different parameter values. Various types of filters are used to decomposition and then analyze texture components. Traditionally, for such problems, a robust Gaussian regression filter and a morphological filter are used. The advantage of the morphological filter lies in the lower computational complexity and the ease of removing the shape component from the profile. This research presents generalized analysis of various types of an asymmetric morphological filter based on simulation. The asymmetric filter differs from the standard morphological filter by using different nesting indexes for combinations of morphological opening and closing operations. We have designed a compositional model of profile, which is superposition of two Gaussian distributions with different parameters and waviness. Relative filtering error of the arithmetic mean heights Ra was chosen as evaluation parameter. Based on the Monte Carlo experiments technique, the relative errors of the filters are determined. The main result of the research is algorithm for choosing nesting indexes depending on the type of primary profile. Thus, we give scientifically justified choice of the filter type and its task-specific parameters for applied use. The choice of filter type and two different nesting indexes in accordance with the developed algorithm provide relative error with a coverage interval less 3 % for 95 % coverage probability. The asymmetric morphological filter is effective for scale space analysis of surfaces with significant shape errors and waviness. The results obtained can be used to analyze the tribological properties of multifunctional surfaces of products.

Non-convex shape effects on the biaxial compression of granular materials composed of monophasic packing and binary mixture

Driven by external compressions or shears, the granular material composed of non-convex shapes often undergoes self-assembly and becomes entangled, resulting in denser packings. In this work, the biaxial compression of monophasic and binary mixture composed of 2D intersecting crosses have been simulated via the discrete element method. As the aspect ratio increases, both the yield strength and elastic modulus initially increase before reaching a peak at w = 0.5. In binary mixtures, an antagonistic effect has been observed in mechanical properties of granular material. The decrease in strength and stiffness in binary mixtures can be attributed to the constraints imposed by multi-point contacts, along with the local order degree, which is particularly unique for non-convex particle packings. Building upon this understanding, we have extended the empirical formula into predicting the mechanical behavior of non-convex binary mixtures. This extension incorporates an additional non-linear term determined by both the shape factor and component fraction.

Role of 3D printed customized implants in periarticular fractures: a narrative review

“3D printing” is a common term used for a number of technologies which operate on the principle of converting a computer-generated 3D image into a physical model. Advantage of 3D printed parts is that they can assume complex shape, with solid and porous components that can be combined to provide the best combination of strength and performances and can help visualize the complex fractures which are difficult to apprehend with conventional imaging. Presently, the primary applications for 3D printing are the production of anatomical models for planning and surgery simulation, patient-specific instruments and custom-made prosthesis which have transformed how orthopedic problems are addressed now. This review aims to describe the utility and future directives into the application of this technology in orthopedics.

Fabrication of Ba0.5Sr0.5TiO3 components combining rapid prototyping with gelcasting using different gelling systems

Barium strontium titanate (BSTO) is a ceramic that finds application as a high-storage capacitor, sensor, detector, transducer and in tuneable microwave devices and as filters. This paper discusses the synthesis of slurries with suspended particles and fabrication of Ba0.5Sr0.5TiO3 components of different shapes and dimensions using environmentally friendly gelling systems like Isobam and methylcellulose, and also the widely used, but toxic, methyl acrylamide system. Suitable moulds made of acrylonitrile butadiene styrene (ABS) and expanded polystyrene (EPS) are fabricated by rapid prototyping and a concentrated slurry of the required ceramic is set in it by gelcasting; the process is referred to as RPGC process. The green body is further processed to obtain a density higher than 98 %. The sintered products are evaluated by measuring density, microstructure and dielectric properties. This work opens up the possibility of adopting the versatile RPGC process with non-toxic organics for applications by industries.

HairManip: High quality hair manipulation via hair element disentangling

Hair editing is challenging due to the complexity and variety of hair materials and shapes. Existing methods employ reference images or user-painted masks to edit hair and have achieved promising results. However, discrepancies in color and shape between the source and target hair can occasionally result in unrealistic results. Therefore, we propose a new hair editing method named HairManip, which decouples the hair information from the input source image into shape and color components. We then train hairstyle and hair color editing sub-networks to handle this complex information independently. To further enhance editing efficiency and accuracy, we introduce a latent code preprocessing module that effectively extracts meaningful features from hair regions, thereby improving the model’s editing capabilities. The experimental results demonstrate that our method achieves significant results in editing accuracy and authenticity, thanks to the carefully designed network structure and loss functions. Code can be found at https://github.com/Zlin0530/HairManip.

Elucidating the morphology and ecology of Eoandromeda octobrachiata from the Ediacaran of South Australia

AbstractEoandromeda octobrachiata is a poorly understood Ediacaran organism, with spiral octoradial arms, found in South Australia and South China. The informal Nilpena member of the Rawnsley Quartzite, Flinders Ranges in South Australia preserves more than 200 specimens of Eoandromeda. Here we use the novel application of rotational geometric morphometrics together with palaeoenvironmental information to provide a better insight into their palaeobiology and ecology, and to address conflicting hypotheses regarding mode of life and taxonomic affinity. We find that Eoandromeda probably had a radially symmetrical shape in life, was cone shaped and had a high relief off the microbial mat. Analysis of the symmetric and asymmetric shape components showed that they deform strongly in the direction of palaeocurrent, therefore they are thought to be made of a flexible material. Almost all specimens are compressed flat. Specimens that appear to have not fully collapsed support the idea that Eoandromeda was probably cone shaped and suggest that they possibly collapsed spirally. Our shape analysis, along with observed morphological features, support a benthic rather than pelagic mode of life. Morphological and ecological inconsistencies do not fully support the hypothesis of a Ctenophora taxonomic affinity.

Defining Epiglottic Collapses Patterns in Obstructive Sleep Apnea Patients: Francia-Lugo Classification

Obstructive Sleep Apnea (OSA) is characterized by repetitive collapse of the upper airway during sleep. Drug-Induced Sleep endoscopy (DISE) is used to identify the collapse site. Among the possible sites of collapse, the epiglottis occurs more frequently than previously described. In this study, we reviewed DISE findings and classified different epiglottic collapse patterns. We found 104 patients (16.4%) with epiglottis collapse (primary 12.5% and secondary 3.9%). We described the following patterns of epiglottis collapse: Anterior–Posterior (AP) collapse with rigid component “trapdoor type” (48%); AP collapse with lax component “floppy type” (13.5%); Lateral– Lateral (LL) collapse with omega shape component “book type” (14.5%); and secondary due to lateral pharyngeal wall or tongue base collapse (24%). The identification of the epiglottic collapse pattern is crucial in decision-making when attempting to ameliorate OSA. These findings in OSA phenotyping could influence the type of treatment chosen.

Flexural strength estimation in edge-damaged silicate glass plates by combined phase-field and visual analysis

The state-of-the-art fractographic guidelines for glasses and fine ceramics, ASTM C1678, are only applicable to limited fracture scenarios. This work outlines a new method to analyze fracture scenarios outside ASTM C1678′s scope. The proposed methodology consists of a two-step process: initially, optical images of the fracture surfaces are obtained, and visual analysis is used to highlight the characteristic fractographic features. Next, the selected features are automatically compared to a baseline set of virtual fracture patterns tailored to any relevant fracture scenarios obtained by numerical phase-field simulations. As validation, scenarios with fractures originating at the glass plates’ edges for both sharp and chamfered corners were analyzed. Strength estimates within 6% of experimental results were achieved with the proposed method. In the future, this technique could be implemented to carry out fractographic analysis on brittle components of arbitrary shapes and loadings, hence substantially extending the application range and accuracy of fractographic methods.

Third molar agenesis relates to human craniofacial form.

To investigate the association between the number of third molars and craniofacial shape. The study sample comprised 470 individuals (194 males and 276 females), out of whom 310 (124 males, mean age: 14.6 years and 186 females, mean age: 14.1 years) had a full permanent dentition including third molars and 160 (70 males, mean age: 13.7 years and 90 females, mean age: 13.9 years) had at least one missing third molar. Pre-orthodontic treatment cephalometric images were digitized using 127 landmarks to describe the shape of the entire craniofacial configuration, the cranial base, the maxilla, and the mandible. The shapes of the various configurations were described by principal components (PCs) of shape. The effect of third molar agenesis on craniofacial shape was evaluated with multivariate regression models, considering shape PCs as the dependent variables, and age and sex as predictors. There was a strong association between third molar agenesis and the shape of all craniofacial configurations in both sexes. Individuals with missing third molars presented a less convex craniofacial configuration, a shorter anterior facial height and a more retrusive maxilla and mandible. In cases with third molar agenesis only in one jaw, shape differences were also evident in the opposing jaw. Interpretation of study outcomes should take into consideration the two-dimensional data and the analysis of only white-European subjects. There is a strong association between third molar formation and craniofacial shape. The effect is rather generalized than local and is potentially linked to an ongoing evolutionary mechanism that leads to smaller and fewer teeth, as well as smaller craniofacial configurations, in modern humans.

Shape- and polymer-considered simulation to unravel the estuarine microplastics fate

Environmental microplastics (MPs) constitute various sizes, polymers, and shape components. In estuaries, such differences are related to the reliability of assessing the seaward fate of MPs, aggregation hotspots, and ecological risks. This study sets the MP particle mass gradient using the shape factor and size probability density function to categorically estimate the MP load in the surface layer of the Yangtze River Estuary (YRE), which is the largest contributor of plastics to the sea. During the high plastic input period in July, the optimized estimated MP load through the surface layer of the YRE was 9766 kg/month, which was overestimated by 821 kg/month based on the empirical average particle mass. While tracking MP transport classified by shape and polymer type, the resuspension of MPs that accumulate in the intertidal zone cannot be neglected. The average relative error of the simulation was as low as 19.6% after including the abovementioned factors. Finally, the simulation results of the sensitive regions were extracted to assess the new MP risk index, which considers shape, abundance, and polymer type. By introducing these essential tools, this study helps to understand the fate of riverine MPs entering estuaries, where valuable opportunities for removing MPs exist before they spread to the oceans.

Ontogenetic skull variation in a shovel-headed amphisbaenian species.

Leposternon microcephalum is a species belonging to the Amphisbaenia, a group of burrowing reptiles. Amphisbaenia present various morphological and physiological adaptations that allow them to penetrate the ground and live underground, through a system of galleries and permanent chambers that they build themselves. Among the morphological adaptations in this group, those of the skull stand out as it serves as the main excavation tool. Four basic skull shapes are recognized: rounded, keeled, shovel-shaped, and spade-shaped. The skull of L. microcephalum belongs to this last type, which is considered the most specialized. The species inhabits soils that are highly compacted and difficult to penetrate. Among the species of Leposternon present in South America, L. microcephalum has the widest distribution, being found in all Brazilian biomes and neighboring countries such as Bolivia, Argentina, Paraguay, and Uruguay. The analysis of the skull of this species was carried out using three-dimensional geometric morphometrics (3D-GMM), a technique that allows comparative analysis, through robust statistical methods, of shape and its variations, using Cartesian coordinate data from a configuration of homologous landmarks. The technique allows the size and shape components of a structure to be analyzed separately. From an ontogenetic point of view, this methodology had also been used to investigate variations in Cynisca leucura, a member of the Amphisbaenidae with a rounded head. Our hypothesis is that the patterns of morphological differentiation in the skull, mainly in the intermediate and occipital regions, are similar in different Amphisbaenia species. Therefore, the objective of this study was to analyze cranial morphological variations in an ontogenetic series of L. microcephalum using 3D-GMM. Computed Tomographic scans of 13 specimens were analyzed: juveniles (N = 8) and adults (N = 5), based on 20 landmarks that characterize the skull. Principal components and regression analyses between shape (dependent variable) and size (independent variable) showed a clear difference between the cranial morphological pattern of juvenile individuals and that of adults. For instance, young specimens tend to have a dorsoventrally tall neurocranium, with the tip of the snout more anteriorly oriented and its dorsal border subtly curved. Dorsally, the parietal region is thicker and smoothly dome-shaped in juveniles. As in C. leucura, the variation was strongly correlated with the size change from juvenile to adult, indicating a dominant role for ontogenetic allometry in determining skull shape.

Oral microbial interactions from an ecological perspective: a narrative review.

Landscape ecology is a relatively new field of study within the sub-specialty of ecology that considers time and space in addition to structure and function. Landscape ecology contends that both the configuration (spatial pattern) and the composition (organisms both at the macro and or micro level) of an ecology can change over time. The oral cavity is an ideal place to study landscape ecology because of the variety of landscapes, the dynamic nature of plaque biofilm development, and the easy access to biofilm material. This review is intended to provide some specific clinical examples of how landscape ecology can influence the understanding of oral diseases and act as a supplement to diagnosis and treatment. The purpose of this review is two-fold; (1) to illustrate how landscape ecology can be used to clarify the two most prominent microbiologically induced infections in the oral cavity, and (2) how studies of oral microbiology can be used to enhance the understanding of landscape ecology. The review will distinguish between "habitat" and "niche" in a landscape and extend the concept that a "patch", is the demarcating unit of a habitat within a landscape. The review will describe how; (1) an individual patch, defined by its shape, edges and internal components can have an influence on species within the patch, (2) spatial dynamics over time within a patch can lead to variations or diversities of species within that patch space, and (3) an unwelcoming environment can promote species extinction or departure/dispersion into a more favorable habitat. Understanding this dynamic in relationship to caries and periodontal disease is the focus of this review.

An advanced rigid-flexible hybrid assembly deviation analysis method for aerostructures

Aerostructures are important components of an aircraft's aerodynamic shape, and their assembly requires high precision. To ensure optimal external shape performance, a significant number of assembly deviation calculations must be performed during the design process of an aerostructure. However, accurately describing shape deviation necessitates high-fidelity surface deformation data. Therefore, an assembly deviation analysis method that balances rapid response and accurate calculation under conditions of large data volume and high cost plays a vital role in promoting the external performance of aerostructures. While some progress has been made in this field, the existing methods are still unable to fill this research gap completely. This paper proposes an advanced rigid-flexible hybrid assembly deviation analysis (RFHA) method for aerostructural shape deviation. It decomposes assembly deviation into rigid deviation transmission and flexible deformation, unifying them in one framework. This method predicts the flexible deformation of aerostructures using discrete cosine transform (DCT) and surrogate model (SM). It also develops a rigid-flexible hybrid assembly deviation analysis method in combination with the Jacobian-Torsor model (J-T). To further reduce computational resources and improve the performance of the surrogate model, the mega-trend diffusion (MTD) is utilized to generate virtual samples to expand the sample set. Relevant parameters of the proposed method are determined using experimental methods. The proposed method is validated and compared with an existing RFHA and a commercial software package. The results show that the proposed method can guarantee prediction performance under small sample conditions and reduce computational burden, while maintaining a certain advantage in rapid response and accurate calculation.

Properties and Lightfastness of Natural and Artificial Azurite Used As Painting Pigment

Azurite is an inorganic pigment commonly used in traditional painting arts and even today. This pigment has two types: natural azurite and synthetic artificial azurite, called blue verditer or blue bice. Because they have the same structure and similar appearance they are difficult to distinguish. The purpose of this study is to compare these two types pigments, focusing on material properties and accelerated weathering behavior. Natural azurite consist of copper carbonate and mineral compounds like quartz, kaolinite. On the other hand, artificial azurites are synthesized using azurite and calcite. As a result of thermal analysis, unlike natural azurite, the calcite in artificial azurite resulted in weight loss at three temperatures, at approximately 350 ℃, 650 ℃, and 840 ℃. According to the microscope analysis results, natural azurites have clearly blue angular particles with sharp edges, produced by crushing. Artificial azurite showed spherules and aggregates with tiny rounded or fibrous particles. After accelerated weathering tests, the natural azurites had no change in color, particle shape or original components, but the artificial azurites noticeably changed color and shape. The color changes of artificial azurites occurred due to the growth of calcite crystallite, a slight new product formation, and change in particle shape. Even though natural azurites are more expensive pigments, they provide superior color durability and particle shape stability compared to artificial azurites.

A design and optimisation framework for cold spray additive manufacturing of lightweight aerospace structural components

Cold spray additive manufacturing (CSAM) is a solid-state deposition process with the potential to produce near-net shape components with complex geometry at a high fabrication rate, making it an attractive alternative to more widely established additive manufacturing (AM) processes. However, CSAM is still in its early stages and requires numerous advancements. The current literature highlights the lack of a design framework for fabricating structural components that encompasses the advantages and constraints of CSAM. This work proposes such a framework to guide product and process engineers, with its novel aspects including (i) accounting for different spray trajectories and their effect on anisotropic mechanical properties, (ii) accounting for the primary constraint for toolpath planning (maximum overhang angle ‘MOA’), and (iii) virtual development and optimisation of a real-world structural component with complex geometry. To exemplify this framework, tensile properties under two spray trajectories were determined experimentally for a common lightweight metal (titanium) supplemented with a ceramic to form a metal matrix composite with improved strength and hardness. Optimisation of the design was conducted via finite element analysis and topology optimisation (TO). Two different TO processes were conducted, namely (i) minimising the strain energy of the structure and reducing the weight by 60% (best stiffness-to-weight ratio) and (ii) minimising the weight by targeting a maximum factor of safety (FoS) value of 1.2. The final design was fabricated via CSAM with relatively little raw material wastage and reasonably close geometric accuracy. Fabrication defects were, however, noticed after making a demonstration component and mitigation measures are discussed within the context of the design framework proposed here.