Geometric Shape Research Articles

Renormalization group model of turbulent bioconvection of gyrotactic microorganisms

The problems connected with processes of turbulent bioconvection are considered. These processes are typical for technologies of microbiological and other industries. The concept of using renormalization groups in the theory of turbulence is shown. A step-by-step algorithm for applying the renormalization methodology to deriving the equation for mass transfer in bioconvective processes, which includes renormalization of the turbulent diffusion coefficient, is presented. The dependence for the turbulent Schmidt number was obtained. It has been shown that turbulent Schmidt number is function of six parameters: molecular Schmidt number, turbulent viscosity, molecular viscosity, parameter of geometric shape of microorganisms, average velocity of motion of microorganisms relative to the fluid, orientation parameter. The turbulent Schmidt number enables closing the diffusion equation. The effect of the geometric shape of microorganisms on the development of turbulence in a bioconvective flow in the presence of gyrotactic microorganisms is analyzed. Analysis shows that microorganisms with spherical symmetry make a small contribution to the formation of turbulent mass transfer processes. The results of the analysis are in a good agreement with data from studies of the nonlinear hydrodynamic stability of bioconvective processes based on the Lorentz model.

Дослідження впливу параметрів процесу хонінгування силікатними брусками на якість обробленої поверхні

Numerous studies have shown that the kinematics of the honing process, which determines the trajectory of the cutting grain during machining, has a major impact on the parameters of macro- and microrelief. The complex working movement during honing of holes creates favourable conditions for the fuller use of the cutting capacity of the bars and uniform wear of the tool, which positively affects the machining performance and accuracy of the geometric shape of the surface. It is shown that, in this regard, there is a need to investigate the influence of the parameters of the honing process with silicate bars on the quality of the machined surface. The paper presents the results of a study of the effect of the contact pressure of the bars and the axial and circumferential speeds on the quality of the treated surface. The study was performed on a vertical single-spindle honing machine. The samples used were cylinder liners of car engines made of grey alloy cast iron. The evaluation was based on the roughness of the machined surface and the mass removal of metal during machining. The best performance was achieved by those bars that resulted in the lowest roughness of the samples. It was found that with an increase in the circumferential speed, the surface quality improves, and with an increase in the axial speed, it deteriorates after processing with diamond, abrasive and silicate stones. With an increase in the contact pressure of the bars, the surface quality deteriorates after machining with diamond bars and improves after machining with abrasive and silicate bars. It has been proven that the high surface quality after treatment with silicate blocks is due to the formation of amorphous silica during honing, which, under the influence of abrasive grains, falls into the cavities of the treated surface and adheres to the surface, thus saturating the treated surface with silicon oxide. It has been established that with an increase in the axial speed of the bars, metal removal increases, and with an increase in the circumferential speed, it decreases after machining with diamond, abrasive and silicate bars. With an increase in the contact pressure of the stones, metal removal increases after machining with diamond stones and gradually decreases after honing with abrasive and silicate stones. It was found that the metal removal after machining with silicate stones is 2 times less than after honing with diamond stones. It is proposed to set the allowance for finishing honing with silicate stones for cylinder liners made of alloy cast iron (HB 240) within 0.01-0.02 mm.

Promuovere lo sviluppo della competenza geometrica: una ricerca nella scuola dell’infanzia

PROMOTING THE DEVELOPMENT OF GEOMETRIC COMPETENCE: A RESEARCH IN KINDERGARTENS Abstract Conducting a research in kindergartens, whose intended impact on the development of children’s geometric competence is to facilitate their learning in later educational stages, involved the collaboration between a pedagogical researcher and a disciplinarian teacher. This collaboration between different areas of expertise represents a key strength of the research presented in this article, which aims at contributing to the reorganisation of curriculum in kindergartens. Through an empirical approach, the research wants to demonstrate the impact that a laboratory teaching path, involving the transition from solid to plane geometry and CAD modelling with 3D printing, can have on classification, representation and sectioning skills of geometric shapes by children at the age of 5.

Learning neural implicit surfaces with local probability standard variance

AbstractReconstructing geometric shapes from sparse multiview has always been a challenging task. With the development of neural implicit surfaces, geometry‐based volume rendering surface reconstruction methods have been proven to be able to reconstruct high‐quality surfaces. However, existing geometry‐based reconstruction methods completely associate volume density with signed distance function or unsigned distance function, resulting in the same volume density peak that can only be reconstructed near the object surface. When there are transparent surfaces in the scene, existing methods prioritize the reconstruction of opaque surfaces, neglecting the reconstruction of transparent surfaces, which is disadvantageous when reconstructing real scenes. To solve this problem, we introduce local probability standard variance, which calculates volume density together with signed distance function. In this way, it can reconstruct the volume density that matches the transparency characteristics of the object surface. The method can reconstruct the surface of transparent objects, and experiments on two transparent surface datasets show that the method performs better.

Soft Corners and Sharp Edges: Exploring Inaccurate Geometric Shapes in Children's Picture Books

Given the inaccuracy of children's picture books on shapes published in English, there was a need to analyse Turkish picture books on shapes. In order to carry out the study on the accuracy of Turkish picture books, a rating rubric for English picture books was translated into Turkish. The Traffic Light Rating Rubric rates books as red (explicit inaccuracies), yellow (implicit inaccuracies or missing concepts) and green (correct concepts). As a result of the research, it was found that the findings for the Turkish books were consistent with the previous findings for the English books. In the majority of the books analysed, the geometric shapes were rated as incorrect (red). Given the importance of early mathematical study for long-term success, the Traffic Light Rating Rubric-Turkish Version is intended to provide guidance to book selectors such as librarians, parents and teachers, and ultimately authors and publishers who need to produce texts with the correct form.

Soft Corners and Sharp Edges: Exploring Inaccurate Geometric Shapes in Children's Picture Books

Given the inaccuracy of children's picture books on shapes published in English, there was a need to analyse Turkish picture books on shapes. In order to carry out the study on the accuracy of Turkish picture books, a rating rubric for English picture books was translated into Turkish. The Traffic Light Rating Rubric rates books as red (explicit inaccuracies), yellow (implicit inaccuracies or missing concepts) and green (correct concepts). As a result of the research, it was found that the findings for the Turkish books were consistent with the previous findings for the English books. In the majority of the books analysed, the geometric shapes were rated as incorrect (red). Given the importance of early mathematical study for long-term success, the Traffic Light Rating Rubric-Turkish Version is intended to provide guidance to book selectors such as librarians, parents and teachers, and ultimately authors and publishers who need to produce texts with the correct form.

Modulation of the electromagnetic shielding effectiveness through micro/macrostructure design for electronic packaging

Lightweight electronic packaging that provides mechanical protection, cooling ability, and customizable electromagnetic interference (EMI) shielding effectiveness (SE) is needed for next-generation electronics. Although electronic packaging solutions with excellent EMI SE exist, there is limited research on how hierarchical design can modulate the EMI SE of an electronic packaging material on demand. In this study, the deliberate precise micro/macrostructure design of graphite-based materials using magnetically assisted 3D printing allows tuning of the EMI SE in the X band (8–12 GHz), leading to a maximum total shielding performance of 90 dB. Aligning high-density graphite microplatelets during 3D printing also remarkably amplified the total SE by 200%. Subsequently, rationally designing the oriented microstructure within a geometrical shape increases the reflection and improves the EMI SE from 40 to 60 dB in a specific direction. Our proof-of-concept samples demonstrate the potential of precise micro/macrostructure design for customizing and enhancing electronic packaging’s EMI SE while achieving good heat dissipation and mechanical protection using a versatile 3D printing method. These advances pave the way for more reliable and safer electronic systems.

Numerical Study on the Influence of Torque Performance Caused by Deflectors on Darrieus Wind Turbines

This paper investigates the effects on the torque performance caused by deflectors of the Darrieus turbine. Various deflectors were placed in front of the turbine and disrupted the wind flow before it came into contact with the turbine blades. Using numerical method, this study aims to find the deflector’s optimum geometric shape, offset distance, and dimension required for the turbine to produce the highest torque. This study utilizes flow simulation analysis to simulate the deflector effect on Darrieus turbine. The result of this study is the optimum deflector geometry and offset distance for producing highest turbine torque output. From the data gathered it is shown that a deflector with triangular cross-section with the size of turbine diameter placed 400 mm offset to the right of the turbine produces the best result. Turbine with this deflector configuration produces 1.24 Nm of torque, eight times higher than its non-deflector counterpart yields 0.14 Nm.

Numerical Study on the Influence of Torque Performance Caused by Deflectors on Darrieus Wind Turbines

This paper investigates the effects on the torque performance caused by deflectors of the Darrieus turbine. Various deflectors were placed in front of the turbine and disrupted the wind flow before it came into contact with the turbine blades. Using numerical method, this study aims to find the deflector’s optimum geometric shape, offset distance, and dimension required for the turbine to produce the highest torque. This study utilizes flow simulation analysis to simulate the deflector effect on Darrieus turbine. The result of this study is the optimum deflector geometry and offset distance for producing highest turbine torque output. From the data gathered it is shown that a deflector with triangular cross-section with the size of turbine diameter placed 400 mm offset to the right of the turbine produces the best result. Turbine with this deflector configuration produces 1.24 Nm of torque, eight times higher than its non-deflector counterpart yields 0.14 Nm.

Relationship between Lesion Parameters after Radiofrequency Catheter Ablation in Striated Muscles and Parenchymal Tissue

Background and Objectives: Radiofrequency catheter ablation (RFCA) is a highly successful intervention. By comparing the lesion changes in prostate parenchymal and striated muscle tissues after RFCA with and without cooling, it was possible to assess the correlation between the shape regularity, area, and perimeter of the thermal lesion, and to predict the geometric shape changes of the lesions. Materials and Methods: A standard prostate and striated muscle RFCA procedure was performed on 13 non-purebred dogs in two sessions: no cooling and cooling with 0.1% NaCl solution. Microtome-cut 2–3 µm sections of tissue samples were stained with haematoxylin and eosin and further examined. The quotient formula was employed to evaluate the geometric shape of the damage zones at the ablation site. Results: The extent of injury following RFCA in striated muscle tissue was comparable to that in prostate parenchymal tissue. Regression analysis indicated a strong and positive relationship between area and perimeter in all experimental groups. In the experimental groups of parenchymal tissues with and without cooling, an increase in the area or perimeter of the damage zone corresponded to an increase in the quotient value. A similar tendency was observed in the striated muscle group with cooling. However, in the striated muscle group without cooling, an increase in lesion area or perimeter lowered the quotient value. Standardised regression coefficients demonstrated that in the striated muscle with cooling, the damage zone shape was more determined by area than perimeter. However, in the parenchymal tissue, the perimeter had a more substantial impact on the damage zone shape than the area. Conclusions: The damage area and perimeter have predictive power on the overall shape regularity of damage zone geometry in both striated muscles and parenchymal tissue. This approach is employed to achieve a balance between the need for tumour eradication and the minimisation of ablation-induced complications to healthy tissue.

Enhanced 4D-OFDM optical communication systems with color-coded constellations and probability constellation shaping

The present work introduces a four-dimensional probability constellation mapping OFDM optical transmission system based on a two-dimensional inverse fast Fourier transform (2D-IFFT). A four-dimensional constellation structure employing color coding is designed, amalgamating geometric shaping with probability shaping to enhance the constellation figure of merit (CFM). Successful transmission of OFDM signals at 51.49 Gb/s is achieved over a 2 km seven-core optical fiber, validating the performance of the proposed constellation diagram. Under the conditions of multicore multiplexing and a bit error rate of 3.8 × 10−3, the receiver sensitivity of the OFDM signals mapped with the proposed color-coded four-dimensional constellation exhibits gains of 0.8 dB, 1.33 dB, and 1.83 dB compared to traditional four-dimensional constellations, 3D-OFDM, and 2D-OFDM modulation, respectively. Furthermore, under an entropy value of 4.4 bits/symbol, a receiver sensitivity gain of 1.36 dB is attained compared to a uniform distribution constellation, indicating the favorable error performance of this scheme with promising prospects for short-distance communication in the future.

Modeling and characterization of contact behavior of asperities with irregular shapes

This paper introduces a model for characterizing the contact behavior of irregular asperities, transforming it into a superposition of sinusoidal asperity contact behaviors. A new sinusoidal asperity model is developed for bilinear hardening under plane strain conditions. Empirical equations are proposed, considering geometric shapes, tangent modulus, and Young’s modulus. The frequency of asperity height is extracted through Fourier transform for irregular asperities. Contact area and pressure are predicted using the sinusoidal asperity model, and the behavior of irregular asperities is obtained by superimposing those with the first three frequencies. Experimental validation is conducted with milling and knurling-formed asperities, showing good alignment between the model and experimental results. In rough surface models, the proposed irregular asperity model exhibits greater accuracy in predicting contact behavior than a single sinusoidal asperity when interference exceeds 10% of the amplitude.

Leaf area estimation based on ANFIS using embedded system and PV panel

Leaf area is one of the important parameters for plant canopy development. It is used as an indicator closely related to plant growth in several studies on plant production. However, most leaf area meters used today are costly and rely on human observations. This situation may be limiting for researchers in terms of having proper leaf area measuring devices. The reliance on human-focused measurements leads to human errors. Digital scanners and cameras, digital image processing-based estimation methods, paper weighing, grid counting, regression equations, width and height correlation models, planimeters, laser optics, and handheld scanners can be used to determine leaf area. However, some of these methods are expensive and unnecessary for simple studies. Therefore, this study aims to design and implement an embedded system with a simpler, cheaper alternative to the currently used methods and devices, minimizing human errors. The proposed embedded system serves as a tool for measuring leaf area using a photovoltaic panel (PV) and an Adaptive Neuro-Fuzzy Inference System (ANFIS). In the study, geometric shapes with known areas are used as the learning data, and real plant leaves with known areas are used in the testing process. As a result, the prediction made by ANFIS is observed to have an accuracy of R2 = 0.99.

Numerical simulation and mathematical modeling of biomechanical stress distribution in poroelastic tumor tissue via magnetic field and bio-ferro-fluid

Based on scientific evidence, it seems that bio-magnetic systems can change the process of cancer cell death by affecting the distribution of pressure and mechanical stress in the tumor tissue. Already most of the research has been done experimentally and few mathematical modeling and numerical simulations have been done to investigate the relationship between the magnetic parameters and the mechanical stress of the tumor tissue. This is despite the fact that in order to be able to make new equipment with the help of medical engineering methods, it is definitely necessary that the mathematics governing the problem and changes in the effective magnetic parameters (such as the shape of the magnetic source, magnetic flux density, magnetic source distance and ferro-fluid volume fraction) should be studied as much as possible. In this research, using numerical simulation and mathematical modeling, four common geometrical shapes (rectangular and circular) of the static magnetic field source were used to investigate the relationship between the change of the effective magnetic parameters and the mechanical stress created in the tumor tissue. The results of this research showed that when the magnetic flux density and ferro-fluid volume fraction and also the distance between the magnet and the tissue are kept constant, as well as without spending any extra energy, for a rectangular magnet, just by changing the way the source is placed on the tissue, the average biomechanical stress inside the tumor tissue causes a 25% change. Also, for a circular magnet, just by doubling the radius of the magnet, the average biomechanical stress inside the tumor tissue causes a 73% change.

Effects of semi‐rigid plastic tray geometry on quality characteristics of a retort food simulant

AbstractThe present study aims to investigate how the geometric shapes of semi‐rigid plastic trays impact the quality characteristics of a retort processed food simulant. Initially, oval, triangular, rectangular, and round‐shaped plastic trays with a tomato‐based food simulant were subjected to retorting at rotational speeds of 6 and 11 revolutions per minute (RPM), and various food quality attributes were assessed. At 6 RPM, triangle‐shaped and round‐shaped trays exhibited a significantly greater reduction (p < 0.05) in ascorbic acid (AA) content compared to oval or rectangular‐shaped trays. Furthermore, there were no significant differences (p > 0.05) in lycopene and hydroxymethylfurfural (HMF) content change from control among the different tray shapes at 6 RPM. However, hexanal content change was found to be greater in rectangular‐shaped trays than in oval‐shaped trays, while no significant difference was observed between triangular and round‐shaped trays. Both triangular and rectangular‐shaped trays showed a substantially greater (p < 0.05) total color difference (ΔE) compared to other shapes. This data suggests the presence of a temperature gradient in the food simulant influenced by the tray's shape. At 11 RPM, oval and round‐shaped trays showed a significant reduction in AA content, while rectangular‐shaped trays exhibited higher lycopene levels compared to oval and round trays. There was an increase in HMF response from control across all tray shapes; however, differentiation between shapes was not significant (p > 0.05), while both triangle and round‐shaped trays had elevated hexanal content as compared to oval‐shaped trays (p < 0.05). Oval, round, and triangle‐shaped trays all exhibited a greater ΔE than rectangular‐shaped trays. In summary, oval and round‐shaped trays exhibited a more pronounced change in AA content at 11 RPM, indicating a faster temperature equilibration. In contrast, triangle and rectangular‐shaped trays displayed elevated total color differences at 6 RPM, which may suggest the presence of a temperature gradient leading to uneven heating due to their respective shapes.Practical applicationsThis information would be applicable to new food products designed for thermal treatment in which the packaging shape could be manipulated to not only fit infrastructure requirements (packaging equipment, processing equipment, distribution devices) but also help support heat penetration at an optimal rate. Depending on product type and makeup, this approach may hold some value to the product developer whose product will be packaged in semi‐rigid plastic containers.

LONet: Local Optimization Network for 3D point cloud semantic segmentation

In the point cloud segmentation tasks, the existing local feature aggregation methods in the up-sampling and down-sampling stages still rely on Euclidean distance to constrain the local aggregation process. However, this approach is susceptible to the influence of abnormal points leading to inaccuracies in fitting the original geometric shape of the point cloud. Therefore, this paper proposes a local gradient aggregation module, which incorporates gradient information of neighboring points during the aggregation process. This enables the model to capture fine-grained geometric information and extract richer local features. Additionally, we introduce a symmetric sampling strategy to improve computational efficiency. The same original mapping indices were used for both up-sampling and down-sampling aggregation. Thus, a large number of additional k-nearest neighbor calculations are avoided. Furthermore, this paper introduces a position-aware encoding in the attention mechanism to address the positional cues for short-term and long-term contexts, facilitating positional-aware communication between points. Numerous comparative experiments prove the effectiveness of the method in this letter. It obtained 72.1% mIoU on ScannetV2, and 72.4% mIoU on S3DIS.

Spatial Distribution Status of Landform in 1st Grade Area of Ecology and Nature Map

In this study, spatial distribution analysis was conducted on the landforms that appear within the 1st grade area using the ecology and nature map of 2023. As a result, a total of 97 landforms including tidal flat and incised meander were identified as unit landforms, and a total of 1,490 sites were distributed. The spatial distribution by administrative region was highest in Gangwon-do with 273 sites (12.8%), and by unit landform, cliff (173 sites), stream cliff (129 sites), and sea cliff (100 sites) were the most distributed. These landforms are cliffs found in mountainous, riverine, and coastal areas, respectively, and are characterized by their high geomorphological conservation value due to their large scale and geometric shape compared to other terrains. In terms of spatial distribution by landform type, stream landforms (501 sites, 33.6%) accounted for the largest proportion, and there were 24 units landforms. The results obtained can be utilized for future designation of expanded ecosystem protection areas or ecosystem monitoring surveys, along with continued landform conservation.

The Development of Android-based Augmented Reality Learning Media in Curved Surfaces Geometry

The increasing level of technology used in the education sector has an impact on the use of technology as a learning media. The research aims to develop and produce an android-based augmented reality learning media in curved surfaces geometry for junior high school students and to know student’s respond to the learning media. The type of this research is research and development and used the Luther-Sutopo Multimedia Development Method. Six stages to develop the android-based augmented reality learning media in geometry are concept, design, material collecting, assembly, testing and distribution. In the fifth stage, testing, the learning media tested at two steps, by validators and student’s respond. The validators gave score as much as 85.95% (valid without revision) for the content and construct materials of the learning media. The students gave good response of learning media, it can be seen from in the usefulness aspect, 70% of respondents agreed that this learning media was useful and could be used in the learning process of curved geometric shapes. For the ease of use aspect 55% of respondents agreed that this learning media was easy to use. For the ease of learning aspect 50% of respondents agreed that this learning media could help them in the process of understanding curved surfaces geometry material and for the satisfaction aspect 65% of respondents felt learning geometry with the help of learning media was fun and would recommend using this learning media to their friends.

Molecular Dynamic Simulations for Biopolymers with Biomedical Applications.

Computational modeling (CM) is a versatile scientific methodology used to examine the properties and behavior of complex systems, such as polymeric materials for biomedical bioengineering. CM has emerged as a primary tool for predicting, setting up, and interpreting experimental results. Integrating in silico and in vitro experiments accelerates scientific advancements, yielding quicker results at a reduced cost. While CM is a mature discipline, its use in biomedical engineering for biopolymer materials has only recently gained prominence. In biopolymer biomedical engineering, CM focuses on three key research areas: (A) Computer-aided design (CAD/CAM) utilizes specialized software to design and model biopolymers for various biomedical applications. This technology allows researchers to create precise three-dimensional models of biopolymers, taking into account their chemical, structural, and functional properties. These models can be used to enhance the structure of biopolymers and improve their effectiveness in specific medical applications. (B) Finite element analysis, a computational technique used to analyze and solve problems in engineering and physics. This approach divides the physical domain into small finite elements with simple geometric shapes. This computational technique enables the study and understanding of the mechanical and structural behavior of biopolymers in biomedical environments. (C) Molecular dynamics (MD) simulations involve using advanced computational techniques to study the behavior of biopolymers at the molecular and atomic levels. These simulations are fundamental for better understanding biological processes at the molecular level. Studying the wide-ranging uses of MD simulations in biopolymers involves examining the structural, functional, and evolutionary aspects of biomolecular systems over time. MD simulations solve Newton's equations of motion for all-atom systems, producing spatial trajectories for each atom. This provides valuable insights into properties such as water absorption on biopolymer surfaces and interactions with solid surfaces, which are crucial for assessing biomaterials. This review provides a comprehensive overview of the various applications of MD simulations in biopolymers. Additionally, it highlights the flexibility, robustness, and synergistic relationship between in silico and experimental techniques.

An analytical study of thermal environment’s effect on the free vibration of FGM double curved FG shells

The main objectif of this work is to examine the thermal environment’s effect of on the free vibration of double curvature shells made of functionally graded materials. A new mathematical model based on higher order shear deformation theory, is developed to incorporate the influence of dependent and independent thermal stresses, which can be uniform, linear, nonlinear, or sinusoidal on the mechanical properties of the double curvature shell. Two material couples, ( S i 3 N 4 / SUS 304 , ZrO 2 /Ti‐6Al‐4V ) , are considered as progressive materials, accounting for temperature-dependent and temperature-independent heat conduction and material properties in the thickness direction. The temperature field is assumed to be uniform across the shell surface but varies only in the thickness direction. The accuracy of the analytical results is validated by comparing them with existing literature results for functionally graded material (FGM) shells with infinite radii under dependent and independent temperature conditions. The study aims to demonstrate the thermal effects on material composition, as well as various specific geometric shapes such as plates, cylinders, spheres and ellipses and how different temperature laws influence the frequencies of vibrating double curvature FGM shells. Both existing theories accurately predict temperature-independent and temperature-dependent vibration responses of the shells. By verifying and comparing the results with the literature, a better agreement is achieved, thereby paving the way for further research in this field.