Geometric Design Research Articles

Reviewing experimental and theoretical efforts and key findings regarding hydrodynamic journal bearing geometry

Abstract Journal bearing operation particularly in regard to marine applications is significantly affected by the performance of the most critical operational factors. Specifically, the lubricating oil film within journal bearing is so often than not subject to hazardous deterioration and ultimate failure in real operating conditions. Considering such fact, the current study is intended to carry out a literature survey regarding the efforts towards enhanced journal bearing performance based on proper selection of geometrical design for journal bearing. The aggregated data were thoroughly analyzed and assessed utilizing experimental, theoretical as well as numerical means. The outcomes derived from the conducted review represent firm grounds for carrying out extensive modifications into journal bearing design for marine applications. Further, such data will possibly be employed in future research investigations to extend the capability of journal bearing and its functions to attain the most possible enhanced performance in actual operating conditions. Apparently, the vast majority of both experimental and theoretical studies into journal bearing geometrical designs for enhanced performance, 66 in all, have been focused on surface texture accounting for 26.67 % (29 research studies) and 32.43 % (33 research studies) of the total investigations under study respectively. Regarding the experimental studies, realizing promoted performance of lubricating oil film by working on pressure profile has evidently obtained the largest contribution representing 35.5% of the overall bulk of the reviewed efforts, Figure 6.

Design of Storm Sewer System for Mass City Using Bentley SewerGEMS Software

Erbil has been undergoing rapid urbanisation and population growth for the last ten years. The impervious surface areas increased, so the volume of runoff generated from stormwater increased. For this reason, the storm sewer system is faced with additional runoff from the urban areas, and the existing sewer system is inadequate. This study focuses on the storm sewer system design using SewerGEMS and AutoCAD Software in Mass City, which is located in the east of Erbil. The topographic map of the study area was created using Civil 3D software and the total station in surveying, and rainfall storm data were collected from Erbil Meteorology Station and the General Directorate of Water and Sewage. Geometric design and hydraulic modelling were done using AutoCAD and SewerGEMS, respectively. The results show hydraulic design parameters such as flow velocity, sewer pipe size, slopes, manholes, pipe profiles, hydraulic grade line, minimum depth of excavation, and the minimum number of drops. Such a model allowed the project to be accomplished in a short time, with high efficiency and low costs; the model effectively demonstrated its ability to improve design and analysis by examining hydraulic performance.

‘안도다다오 건축에서 나타난 기하학적 공간 특성’에 관한 연구

This study is a research paper that derives the geometric design characteristics that appear in Tadao Ando's architecture. The purpose of this study is to theoretically analyze Tadao Ando's architecture and geometry and derive those characteristics through examples of recent domestic buildings since 2010 by Tadao Ando. . The method of this study is to study literature related to theory and analyze cases through architectural collections. Based on Tadao Ando's architectural concept and the meaning of geometry, the characteristics of combined geometry, disconnected geometry, and independent geometry were derived. In addition, a building case analysis was conducted based on geometric spatial characteristics. Tadao Ando's architecture is composed of six methods: juxtaposition, separation, expansion, overlap, transformation, and absorption, and the substantial form of space becomes existential meaning through spatial recognition and becomes essential architecture. Based on this study, we hope to develop research into the essential concepts of geometric space characteristics that appear in architectural space.

Round Heaven and Square Earth, the Unity of the Pagoda and Statues—A Study on the Geometric Proportions of the Architectural Space, Statues, and Murals in Ying Xian Fogong Si Shijia Ta 應縣佛宮寺釋迦塔 (Sakyamuni Pagoda of Fogong Temple in Ying County)

In Ying Xian Fogong Si Shijia Ta 應縣佛宮寺釋迦塔 (Sakyamuni Pagoda of Fogong Temple in Ying County), Shanxi, there are statues set on each floor, and 26 exist in total, with six murals painted on the first floor. The pagoda was designed as a vertically rising Buddhist temple, and the interior space of each floor was customized for the statues. Based on previous research and through surveying and mapping of the architecture and statuary (including the murals on the first floor) combined with geometric design analysis, this paper proposes the following: First, there exists a clear geometric proportion among the interior space and statues on each floor of the pagoda. Second, clear proportional relationships also exist among the statues on each floor, and each of the 26 statues has ‘classical’ proportion rules. Third, the height of the giant Buddha statue on the first floor is the module for not only the height of the statues on each floor but also the construction of the whole pagoda such that the height of the statue on the first floor is 1/6 of the total height of the pagoda (excluding the base). And the ratio of the pagoda’s total height to the first floor’s diameter, the ratio of the total height to the top-story height under the column capital, and all the other geometric proportions are closely related to the architectural modeling. And finally, in the construction of the pagoda, statues, and murals, the scale is deduced to be 1 chi 尺 (Chinese foot) = 29.5 cm. These values give clear scale logics not only to the construction but also to the details of the statues. Accordingly, the most frequently used proportions in the architectural space, statues, and murals of the Pagoda of Fogong Temple are 2, 3:2, 5:3 (or 8:5), and 9:5, which are imbued with cultural messages, like Zhou Bi Suan Jing 周髀算經 (The Mathematical classic of the Zhou shadow-gauging instrument), Ying Zao Fa Shi 營造法式 (Treatise on Architectural Methods or State Building Standards), the ancient Chinese world view—tian yuan di fang 天圜地方 (the dome-shaped heaven and the flat, square earth) reflected from “ yuan fang tu 圓方圖 (rounded-square map)” and “fang yuan tu 方圓圖 (squared-circle map)”, ancient Chinese ideas that ”san tian liang di er yi shu 參天兩地而倚數 (‘three’ is the number of the heaven and ‘two’ is the number of the earth, and all numbers are based on them)” and “jiu wu zhi zun 九五之尊 (nine and five are the numbers of the honorable central position)”, and most probably related to the “mandala” of Esoteric Buddhism and to the Western “Golden Ratio”, which all need further research in depth.

Geometric Modelling of a Family of 3-point Quaternary Subdivision Schemes Rζ

Computer-aided geometric design combines mathematical concepts and computing skills that smooth curves through subdivision schemes. Subdivision schemes perform smoothing by turning the control polygon into a limit curve under a refinement rule, a prime example of which is improving the signal-to-noise ratio in modern devices. Because of the importance and location of subdivision schemes, mathematicians use them in CAD, computer graphics and advanced simulation methods. In this research, a family of 3-point Quaternary approximating subdivision scheme $R_{\zeta}$ is presented with its properties and analysis, including necessary conditions for convergence, Laurent polynomial, degree of the generation and polynomial reproduction, continuity analysis, Hölder regularity, and limit stencils. The visual performance of the proposed scheme is also presented to highlight the importance of this research and to validate the scheme.

Verification and Establishment of Techniques of Ajami Artwork

Ajami, a technique of painted wood paneling, was popular in the Ottoman Empire from the 17th to the late 18th centuries. Ajami art became prominent in Syria after the decline of tile production, and it rose to a sophisticated level of art in both local and global markets. Today, however, Ajami art has become almost forgotten and unknown by the modern generation, due to being an exclusive art that can be seen only in palaces, museums, and historical houses. This study investigates the traditional method and techniques of making Ajami, with a focus on the work of a renowned Syrian Ajami art master artisan named Mr. Abdulraouf. The study aims to identify and document the traditional method of Ajami production and determine the materials and techniques used for making Ajami. The study found that Ajami art consists of natural elements that are utilized in four main stages; foundation, design, painting, and finishing. The artisans have a strong preference for floral and geometric designs, influenced by Islamic religious beliefs. The findings of this study could serve as an educational guide to preserve heritage and make it presentable for the present and future generations.

Development of a control co-design optimization framework with aeroelastic-control coupling for floating offshore wind turbines

Sequential design optimization is frequently used to design floating offshore wind turbines. This method simplifies the design problem by implementing each of the disciplines successively and independently with the direct/dynamic coupling between them neglected. However, if the coupling between disciplines is strong, the global optimum may not be found by sequential design. Control co-design optimization is an approach that integrates all physics in a single optimization formulation to achieve the global optimum. However, it is challenging to achieve due to the highly complex system-control coupling in floating offshore wind turbines. This paper describes a control co-design optimization framework developed for floating offshore wind turbines. In particular, the blade airfoil chord and twist distributions are parameterized to change aerodynamics while the blade structural characteristics can be updated. The rotor speed and blade pitch controllers are tuned automatically based on the properties of the new plant model. For demonstration, a 10 MW reference wind turbine is used in the case study. The annual energy production is maximized, and the blade mass is minimized. The blade shape and control parameters are optimized simultaneously, subject to constraints on geometric design variables, fatigue loads, ultimate loads, and blade deflection. To solve this high-dimensional, nonlinear, and constrained problem, a genetic algorithm is used, and the Pareto front of the design space is found. The design solutions on the Pareto front showed an improvement in the blade mass and annual energy production. These design alternatives also showed reduced structural ultimate and fatigue loads, and generator torque. This revealed the potential of control co-design to reach a better performance than the sequential method.

Geometric design of carbon-based interlayer for advanced lithium-sulfur batteries

Interlayer engineering is considered as an innovative and efficient approach to constrain the shuttle effect of polysulfides while elevating sluggish redox reaction kinetics in lithium‑sulfur (LiS) batteries. However, the principles for functional interlayer design have not been scientifically established yet, as very few works have focused on the investigation of parameters (e.g., geometrical structure) that affect the electrochemical performance of interlayer. In this study, interlayers with identical chemical compositions but different micromorphologies are fabricated by polyacrylonitrile, including nanofiber, short stick, and powder. Multiphysics simulation and experimental results reveal that the distinctions in the microcrystalline interlayers lead to completely different suppression effects on polysulfides. Notably, the 3D carbon nanofiber-modified interlayer (NF) prepared from electrospinning technology forms a higher specific area and continuous electron access compared to short sticks and powder. Accordingly, the NF-based LiS battery exhibited excellent cycling performance at 1.0 C, with a reversible capacity of 660 mAh g−1 after 300 cycles and a decay rate of about 0.10 %. Even at a high sulfur loading of 8.2 mg cm−2, it achieves a high areal capacity of 5.1 mAh cm−2 after 100 cycles at 0.2 C. This study clearly elucidates a design strategy for high-performance interlayer in LiS batteries from a mesoscale perspective.

Bidirectional tuned liquid dampers for stabilizing floating offshore wind turbine substructures

Tuned sloshing dampers have long been used to stabilize tall and thin buildings and are now being applied to marine structures. In this study, the effectiveness of two new passive control devices at stabilizing floating offshore wind turbine substructures was investigated: the bidirectional tuned liquid damper and bidirectional tuned liquid column damper. Numerical simulations were performed to consider the sloshing effect on the passive control devices and the pitch-induced external moment brought about by wave action. The effects of adding baffles and orifices to the passive control devices were explored to optimize the geometric design. The results showed that the optimal combination of substructure geometry and passive control device type could reduce the pitch motion by 20%–40%.

Micro- and Nanoengineered Metal Additively Manufactured Surfaces for Enhanced Anti-Frosting Applications.

The greater geometrical design freedom offered by additive manufacturing (AM) as compared to the conventional manufacturing method has attracted increasing interest in AM to develop innovative and complex designs for enhanced performance. However, the difference in material composition and surface properties from conventional alloys has made surface micro-/nanostructuring of AM metals challenging. Frost accretion is a safety hazard in numerous engineering applications. To expand the application of AM, this study experimentally investigates the antifrosting performance of superhydrophobic and slippery lubricant-infused porous surfaces (SLIPSs) generated on AM alloy, AlSi10Mg. By strategically utilizing the subgrain structure in the metallography of the AM alloy, the functionalized superhydrophobic AM surface featuring hierarchical structures was shown to greatly reduce frost formation as compared to functionalized single-tier structured surfaces, hierarchical structures formed on conventional aluminum alloy surfaces, and SLIPSs. Optical observation of frost propagation demonstrated that the mechanism of frost delay is governed by the inhibition of spontaneous droplet freezing through exceptional Cassie state stability during condensation frosting. The Cassie stability results from the unique AM structure morphology, which creates a higher structural energy barrier to prevent condensate from infiltrating the cavities. This phenomenon also enables the formation of a high surface-to-droplet thermal resistance, which eliminates spontaneous droplet freezing down to a -15 °C surface temperature. Our work demonstrates a scalable structuring method for AM metals, which can result in delayed frost formation, and it also provides guidelines for the development of engineered surfaces requiring the antifrosting function for several industries.

Optimizing heterogeneous elastic material distributions on 3D models

Optimizing heterogeneous elastic material distribution on a 3D part to achieve desired deformation behavior is an important task in computer-aided design and additive manufacturing. This paper presents a solution to this problem, which involves interactive design, automatic deformation generation, and optimization of spatial distribution of heterogeneous elastic materials. Our method improves previous techniques in three aspects. First, we incorporates a geometric deformation-based interactive design into FEM-based optimization, which makes the solution less dependent of initial guesses of Young’s modulus values and it more likely to produce the target design even with sparse user input of displacements and forces at a limited set of mesh vertices. Second, we formulate the problem as an L2- or L0-optimization problem. The L2 formulation outputs smoothly varying heterogeneous material distribution that accommodates multiple functions within a single part. The L0 formulation achieves the computation of sparse material distribution in one step, which is beneficial for additive manufacturing with multi-material printers. Third, we utilize the adjoint method to derive formulae for efficiently computing the gradient of the objective functions, making it possible to quickly solve the optimization problem in the full-dimensional space of materials, which was previously infeasible. The experiments demonstrate the robustness and efficiency of our approach.

Memory function in autoimmune encephalitis: a cross-sectional prospective study utilising multiple memory paradigms

Background and objectiveAutoimmune encephalitis (AE) is often associated with clinically significant memory impairment. This study aimed to evaluate memory in a cross-sectional prospective AE cohort using multiple memory paradigms.Methods52 patients (50% seropositive) meeting Graus criteria for possible AE were prospectively recruited between October 2019 and August 202. A comprehensive examination of memory was performed, including tests of supraspan verbal memory (list learning), logicosemantic memory (story learning), figural memory (learning of geometric designs), and verbal associative learning (verbal paired associates). Memory scores were compared to demographically adjusted normative data. Pattern analysis was conducted to assist in the identification of patterns in memory performances.ResultsMean memory scores were not significantly below the normative mean. At an individual patient level, over 20% of the cohort exhibited impaired delayed figural memory, supraspan verbal memory learning and recall. Observed performances were significantly below expected performance for story learning (p = 0.017) and recall (p = 0.003), figural recall (p < 0.0001), initial acquisition (p < 0.001) and final acquisition of a list (p < 0.001) and all delayed recall measures of the list (p < 0.00001). 54.76% of patients exhibited intact psychometrics, and 16 distinct patterns of impairment emerged, indicating variability in memory outcomes.DiscussionWhile statistical evidence for memory impairment did not emerge at an aggregate level, a proportion of patients present with evidence of abnormal memory performance on psychometrics. Variability in impaired memory measures argues for an individualised patient-focused approach to clinical assessment in AE. Future research should validate these findings with a larger sample size and explore the relationships between memory profiles and other cognitive functions.

Design of geometric flower pattern for clothing based on deep learning and interactive genetic algorithm

Abstract Geometric and floral models are an important part of clothing and have been used for thousands of years. Although the styles of geometric models and flower models have undergone changes over the centuries, they are still one of the important factors of clothing patterns, the important carrier of aesthetics, and the manifestation of people’s spiritual views and cultural needs. The development and application of digital printing technology have freed people from excessive dependence on sewing and embroidery processes. Therefore, while deeply studying the design of clothing patterns, this work sorted and analyzed the geometric flower models of clothing through interactive genetic algorithms, and optimized programming to enrich the models of clothing with geometric textures. The results showed that the deviation value of geometric flower pattern design was constantly decreasing, while the optimal strategy value was constantly increasing. The mean deviation value was 0.82, which was a decrease of 0.21 on the seventh day compared with the first day; the mean value of the optimal strategy value was 0.84, which was an increase of 0.19 on the seventh day compared with the first day. The visual effect and creativity of the clothing flower pattern design under the interactive genetic algorithm are better than the traditional flower pattern design, and the visual effect and creativity under the interactive genetic algorithm are 9% higher than the traditional one.

Diseño de estructuras hidráulicas en régimen supercrítico con sedimentos: un criterio matemático para calcular la rugosidad del fondo

In some channels with high gradients, heavy scouring and erosion, as well as overflow, is highly common to occur, thus it is required a water flow velocities regulation. An option for achieving this, is to significantly increase the channels’ s bottom roughness through the installation of rapid hydraulic structures. However, in sedimentary density fluids, the change of velocity generates the deposition of solids which could be consolidated by changing the geometric design of these structures. This study aims to estimate the degree of confidence expected when modifications take place to artificial roughness geometries in the bottom of the channel with turbulent flow and sediment flow. This modification requires to transverse ribs into ramps using an experimental mathematical analysis. The study allows us to conclude that the newly generated bottom roughness causes more stable water flows, and it is a way to reduce flow velocities.

Investigation of the influence of bridge support configurations on local bottom erosion when changing the flow direction on the approach to the bridge crossing structures

The analysis of the impact of bridge crossings is based on calculated studies of local erosion on the Belaya River section in the alignment of Vorovsky Street in Ufa in 2021, where a new bridge crossing is currently planned to be commissioned. Due to the complexity of the process of interaction of the turbulent flow with the geometric design of the supports. The main criteria of the analysis are the shape and width of the bridge supports, as well as the direction of flow relative to the bridge support. The results showed possible changes in the depth of local erosion at the approaches to the bridge. In order to simplify the calculation and to find the greatest criteria affecting the effective indicator of local erosion, a factor analysis of the obtained values was performed in the work.

Generation of fractal curves using new binary 8-point interpolatory subdivision scheme

The subdivision scheme is a valuable tool for designing shapes and representing geometry in computer-aided geometric design. It has excellent geometric properties, such as fractals and adjustable shape. In this research paper, we explore the generation of fractal curves using a novel binary 8-point interpolatory subdivision scheme with two parameters. We analyse different properties of the proposed scheme, including convergence, special cases, and fractals. Additionally, we demonstrate through various examples the relationship between the shape parameters and the fractal behaviour of the resulting curve. Our research also identifies a specific range of shape parameters that can effectively produce fractal curves. The findings of this study provide a fast and efficient method for generating fractals, as demonstrated by numerous examples. Modelling examples show that the 8-point interpolatory scheme can enhance the efficiency of computer design for complex models.

A systematic review of the explicit knowledge used and evidence base in the process of design and fabrication of orthopedic footwear

BACKGROUND: The design and manufacturing of effective foot orthoses is a complex multidisciplinary problem involving biomedical and gait pattern aspects, technical material and geometric design elements as well as psychological and social contexts. This complexity contributes to the current trial-and-error and experience-based orthopedic footwear practice in which a major part of the expertise is implicit. This hampers knowledge transfer, reproducibility and innovation. OBJECTIVE/METHODS: A systematic review of literature has been performed to find evidence of explicit knowledge, quantitative guidelines and design motivations of pedorthists. RESULTS: 17 studies have been included. No consensus is found on which measurable parameters ensure proper foot and ankle functioning. Parameters suggested are: neutral foot positioning and control of rearfoot motion, maximum arch, but also tibial internal/external rotation as well as a three point force system. Also studies evaluating foot orthoses centering on the diagnosis or orthosis type find no clear guidelines for treatment or for measuring the effectiveness. CONCLUSIONS: A gap in the translation from diagnosis to a specific, customized and quantified effective orthosis design is identified. Suggested solutions are both top-down, fitting of patient data in simulations, as well as bottom-up, quantifying current practices of pedorthists in order to develop new practical guidelines and evidence-based procedures.

Multi-objective optimization and sensitivity analysis of offset strip fin compact heat exchangers

In this study, the aerothermal performance of Offset Strip Fin Compact Heat Exchangers (OSF-CHE) is optimized with the multi-objective Particle Swarm Optimization method. Available empirical correlations for the Fanning factor and Colburn factor are utilized in the optimization process. Selected off-design Pareto-optimal solutions for compact heat exchanger configurations are reconstructed and simulated by Computational Fluid Dynamics simulations at various boundary conditions after extensive validation processes. Optimized OSF-CHE designs are shown to have improved aerothermal performances among comparable designs in the literature. It has been shown that a high Reynolds number in the range of 1,500–2,000 as a flow attribute provides the Fanning factor ranging from 0.0228 to 0.0619 and the Colburn factor between 0.0067 and 0.0122 and Re is more dominant than geometric design variables on the objective functions. Low and moderate Reynolds number flows at 500 and 1,000 offer a wider selection range for both objective functions on the Pareto-front.

Study and optimization of process parameters for deformation machining stretching mode

Monolithic thin-structure parts with intricate geometric designs are employed in a variety of aeronautical, medical, marine, and automotive applications, which include the moldlines of the fuselage, turbine blades, impellers, avionic shelves, irregular fins, prostheses, bone and joint support, and skull plates. The deformation machining process is the solution to this challenging and difficult-to-manufacture high-quality components with intricate narrow geometries at competitive prices. The aim of the present study is to assess the effect of process parameters of the deformation machining process wherein a thin, floor-like structure is created by milling and is then formed using a single-point incremental forming tool. Investigation involves the design and development of tooling required for the process followed by feasibility checking of the process. To examine the impact of different process parameters on the process response, the experiments were carried out using the design of experiments. The findings of this study indicate that different process parameters, including spindle speed, tool diameter, incremental step depth, and feed rate, have a substantial impact on the process response, like thickness, surface finish, and hardness. Uneven and non-uniform surface patterns during SEM indicate that it is needed to examine the impact of process parameters. This research involves the feasibility study of a new hybrid technique of deformation machining. Conventionally, a metallic structure is produced by joining various components through welding or by fastening. These methods require additional expenditure on equipment, storage, floor space, human resources, etc., with higher lead time. Joining increases weight and reduces fatigue strength. The creation of monolithic structures can eliminate all these disadvantages.

Mechanical Characteristics of Sandwich Structures with 3D-Printed Bio-Inspired Gyroid Structure Core and Carbon Fiber-Reinforced Polymer Laminate Face-Sheet.

The gyroid structure is a bio-inspired structure that was discovered in butterfly wings. The geometric design of the gyroid structure in butterfly wings offers a unique combination of strength and flexibility. This study investigated sandwich panels consisting of a 3D-printed gyroid structure core and carbon fiber-reinforced polymer (CFRP) facing skin. A filament fused fabrication 3D printer machine was used to print the gyroid cores with three different relative densities, namely 10%, 15%, and 20%. Polylactic acid (PLA) was used as the printing material for the gyroid. The gyroid structure was then sandwiched and joined by an epoxy resin between CFRP laminates. Polyurethane foam (PUF) was filled into the gyroid core to fill the cavity on the core for another set of samples. Flexural and compression tests were performed on the samples to investigate the mechanical behavior of the sandwiches. Moreover, the two-parameter Weibull distribution was used to evaluate the results statistically. As a result, the sandwich-specific facing stress and core shear strength from the three-point bending test of the composites increased with the increase in sandwich density. Core density controls the flexural characteristics of the sandwich. Adding PUF improves the deflection at the maximum stress and the sustained load after fracture of the sandwich. Compression strength, modulus, and energy absorbed by gyroid core sandwiches and their specific properties are higher than the PUF-filled gyroid core sandwiches at equal sandwich density.