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Copyright of Low-Carbon Materials & Green Construction is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate representation of spinal geometry is necessary in biomechanical modelling to properly understand the function of the spine. The objective of this study was to create a large database of image-derived digital spine surface models for geometric studies and computational biomechanics investigation. Computed tomography scan data was acquired from 60 asymptomatic subjects (30 males and 30 females). Subjects ranged in age from 20 to 68 with equal numbers selected in each 10-year age bracket. Three-dimensional geometric surface models were generated for each subject's spine. A series of distance measures were also computed for each vertebral body to assess variation in the population. Geometric measures were able to show the significant variation in vertebrae size and shape within the subject population and as a function of vertebral level, gender, and age. This database enables the biomechanical evaluation of the variation in spinal loads that occurs within the population due to geometry. [ABSTRACT FROM AUTHOR]

Abstract Segregation results in worse mechanical and durability performance of concrete. Therefore, an accurate modelling of segregation is required for reliable mesoscale modelling. In this context, this paper presents a method to develop the geometric mesoscale modelling of concrete taking into account segregation. In this method, coarse aggregate particles are generated as ellipsoids of random geometry and are randomly placed within concrete. The specimen is stratified in different numbers of layers ( $$NoL$$ NoL ) that represent different segregation conditions. The geometric models of four concrete mix designs are generated and the relevant key parameters, e.g. aggregate distribution are analysed and validated. In addition, the segregation level of generated models is classified based on the volumetric index and the correspondence between segregation level and the value of $$NoL$$ NoL is presented. The results show that 1) The generated geometric models with $$NoL$$ NoL ranging from 1 to 10 align well with real segregation in concrete and can accurately represent the majority of segregation cases resulting from various experimental factors; 2) The $$NoL$$ NoL reflects the segregation level: more layers indicate a more heterogeneous mesostructure; 3) The larger aggregates of the generated models tend to settle at the bottom, while smaller aggregates rise toward the top, leading to uneven vertical distribution, especially as the $$NoL$$ NoL increases; 4) the mix 1 with low aggregate content can represent the construction material with large segregation, while the mix 2 is inverse.

This article describes a method for calculating the volume of a silver vessel "with a rosette" from the Maikop burial mound using a refined geometric model. It is concluded that the calculated volume is close to the upper limit of the volume of the large holes on the Pyatikhatki slab, and corresponds to the volume of the holes L11 and L12, which could serve to measure time between from 10 o'clock to 11 o'clock (10 a.m. - 11 a.m.) and from 11 o'clock to 12 o'clock (11 a.m. - 12 p.m.). Thus, the calculations using the refined model confirm the conclusion based on approximate calculations of the volume of the vessel body as a sphere, that the silver vessels from the Maykop kurgan could function as accumulative water clocks. And their volume corresponded to the volume of water for measuring one hour in the Mesopotamian metric tradition.

Geometric modeling of interval sets of multidimensional space is considered. The interval set is determined as a set of k-planes of uncertain interval parameters. Interval parameters may be given by means of interval basis which are k-simplexes having vertex coordinates which are not fully presented (only up to range of values). Geometric images of the sets have combinatorial structure formed by some part of the space and bordered by a set of peace linear hyper-surfaces. Analytic model is a system of interval equations which may be transformed to equations with uncertain parameters. The set of interval parameters generate an interval function and geometric image of it is some domain in parametric space. Analyses of mutual position of all domains allows us to determine the behavior of interval sets. Some properties of interval line sets are considered in detail as examples of the proposed approach.

Weft-knitted jacquard plush fabrics are widely used and have a wide variety of varieties, but the design and production process is complicated, time-consuming, and labor-intensive. To reduce the time and cost of fabric sampling and production, a method for designing and simulating these fabrics is proposed based on an analysis of their structural characteristics. Following the design principles of weft-knitted jacquard plush fabrics, mathematical models for pattern design and structural design were established sequentially, leading to the generation of a mathematical model for the knitting diagram. Arrays for raw material editing and threading editing were created to set various parameters. Second, loop models were established based on plush loop shapes, including a forming loop model, a U-shaped loop model, a Henkel plush loop model, a “8”-shaped plush loop model, and a O-shaped plush loop model. Finally, the effects of lighting and number of segments were investigated in THREE.Tube Geometry on the simulation’s effectiveness and speed. By comparing actual fabric images with simulation images, the feasibility of the design and simulation method was verified. This resulted in a computer-aided design process for weft-knitted jacquard plush fabrics, providing an effective method for their design and simulation. The proposed method holds significant theoretical and practical values.

In order to derive the structural properties and deformation behavior of the weft-knitted transfer fabric, a multilayer spring-mass geometric circle model with weft-knitted transfer loop is provided in conjunction with the fabric samples’ image. Eight type-value points were utilized to control the transfer loop’s morphological structure. Connections between the type-value points and the particle system were established. Non-uniform rational B spline curves and texture mapping were utilized to create the three-dimensional impression of the weft-knitted transfer loop. By measuring the offset of the type-value points in conjunction, the actual deformation of the weft-knitted transfer fabric was determined. Utilizing a cylindrical envelope box for collision detection, the possible unreasonable interpenetration phenomenon in the simulation was solved, and thus a stable weft-knitted transfer loop structure was obtained. Using Microsoft Visual Studio and C#, the deformation of the weft-knitted transfer fabric was simulated, the simulated weft-knitted transfer fabric’s deformation pattern accurately depicts the fabric’s three-dimensional structure and deformation behavior while also matching the structural characteristics of the fabric sample. The findings demonstrate that the theoretical structural model of weft-knitted transfer fabric constructed can accurately represent the loop’s structure, and the actual deformation of the simulated weft-knitted transfer fabric is consistent with the deformation characteristics of the fabric sample. Weft-knitted transfer fabric’s deformation behavior may be effectively reflected by the multilayer spring-mass geometric circle model, allowing for the modeling of the fabric’s morphology and 3D structure.

Abstract Wooden buildings represent a unique aspect of China’s architectural heritage. However, over time, these buildings have suffered varying degrees of structural damage, particularly those located in China’s mountainous regions. Frequent natural disasters and inconvenient transportation further exacerbate the vulnerability of these structures. This study focuses on the typical wooden stilt houses found in the Wuling Mountain area of southwest Hubei. The different forms of columns and beams, as well as the overall structural symmetry of the stilt houses, were classified into five common structural types. Precise digital models were established via real photos and collected dimensional data, and these five models were evaluated for static, buckling, utilization, and ultimate limit states. The results indicate that: (1) overall symmetrical structures perform better than asymmetrical ones; (2) structures where all columns are grounded and act as support columns exhibit the best overall mechanical performance; and (3) transverse-tie beams(chuanfang) primarily serve a connecting role rather than a load-bearing role, thus an excess of transverse-tie beams(chuanfang) can reduce the stability of the building structure. Based on the analysis results, targeted protective measures and recommendations were proposed and verified through structural evaluations. These initiatives provide new methods and insights for the protection of architectural heritage.

This article presents a study on developing and verifying a computational model of the aerodynamics of a fan with a wing. The main goal was to create an accurate and reliable model to predict the fan's aerodynamic characteristics under various conditions using advanced computational fluid dynamics (CFD) methods implemented in ANSYS software. The development process included creating geometric and mesh models, setting boundary conditions, and performing numerical calculations. Emphasis was placed on grid independence and numerical convergence analysis, allowing optimal model parameter selection for accuracy with minimal computational costs. Simulation results accurately predicted key aerodynamic characteristics such as thrust, friction, and pressure coefficients. Using this model at the design stage enabled early identification and resolution of potential problems, improving fan aerodynamics and increasing energy efficiency. Benefits include reduced operating costs and lower carbon dioxide emissions, which is particularly relevant given rising energy prices and stricter environmental regulations. This model can be adapted for other ventilation systems, opening new opportunities in various industries and aviation. The study highlights the importance of developing accurate computational models, not only for predicting aerodynamic characteristics but also for improving the design and operation of ventilation systems. These models save time and resources, enhance product quality and reliability, and have a significant impact on engineering systems. [ABSTRACT FROM AUTHOR]

Relationships between difference and differential equations are examined, to understand why the applications of the first to problems of real life, are not as well developed as the applications of the second. In this goal, a review of journals devoted to both types of equations is done, strengthened by the analysis of the MSC2020-Mathematics Subject Classification System. The screening of 296 Issues of the Journal of Difference Equations and Applications published since 1995 highlights that only a low ratio of the published papers are concerned with applications, even if this ratio is slightly increasing for 27 years. An analysis of first, what are possible relationships between actual problems and difference equations, and second, what could be an application of difference equations are discussed. Finally, some avenues of work to increase the number of applications are explored. [ABSTRACT FROM AUTHOR]

When exploring the mechanical behavior of 3D woven composite under multi-axial loading, a tube sample is a feasible and easily accessible option for testing. And the investigation of performance of 3D woven composite tube under tension and torsion with finite-element method (FEM) as a tool requires a fundamental geometric model. With the idealizations of that warp is nearly rectangular and weft is nearly lenticular expressed with cubic functions, a 3D woven composite tube RVE geometric model is presented in this paper which is featured with the various cross-section shape along the yarn path. This model also takes the vertical misalignment of weft yarn stacks and flatten weft cross-sections in the surface into account. Comparing to the architecture in a real sample with each two slices from the tube circumferential and axial direction view, the largest prediction error is 6.80% while the least is 0.66% in terms of RVE dimensions, and the predicted area, width and height average error is 5.21%, 7.89% and 9.11%, respectively, validating the proposed 3D woven composite tube RVE geometric model which can be further used for mechanical behavior prediction and damage propagation. [ABSTRACT FROM AUTHOR]

Wooden buildings represent a unique aspect of China's architectural heritage. However, over time, these buildings have suffered varying degrees of structural damage, particularly those located in China's mountainous regions. Frequent natural disasters and inconvenient transportation further exacerbate the vulnerability of these structures. This study focuses on the typical wooden stilt houses found in the Wuling Mountain area of southwest Hubei. The different forms of columns and beams, as well as the overall structural symmetry of the stilt houses, were classified into five common structural types. Precise digital models were established via real photos and collected dimensional data, and these five models were evaluated for static, buckling, utilization, and ultimate limit states. The results indicate that: (1) overall symmetrical structures perform better than asymmetrical ones; (2) structures where all columns are grounded and act as support columns exhibit the best overall mechanical performance; and (3) transverse-tie beams(chuanfang) primarily serve a connecting role rather than a load-bearing role, thus an excess of transverse-tie beams(chuanfang) can reduce the stability of the building structure. Based on the analysis results, targeted protective measures and recommendations were proposed and verified through structural evaluations. These initiatives provide new methods and insights for the protection of architectural heritage. [ABSTRACT FROM AUTHOR]

Seat tilting wheelchair features can increase the comfort and safety of the user. Although many power wheelchairs have tilting mechanisms, they are often designed with a specific wheelchair model in mind. In this study, a design process for seat tilting mechanisms that can be applied to most rear-wheel drive wheelchair models is developed. Equations were developed to describe the geometrical and load constraints that were used to size the electric actuator that powers the system and define its position. Finally, the equations were used to create the seat tilting mechanism of a prototype wheelchair, which was then tested. The equations yielded coherent results which showed that advantageous actuator positions from a load minimization perspective usually require dimensions that cannot be found in commercial actuators. Also, there are positions in which the load increases exponentially, which should be avoided. The tests showed that the system was able to function properly on the prototype wheelchair and that the actuator position affected the time taken for the actuator to execute different parts of the tilting movement. The design process presented here was successful and modelled by general equations that can be applied to most front-wheel drive wheelchairs. It presents a low-cost option for the design of seat tilting systems, which can increase their accessibility. Developing new systems to provide improvements in assistive technologies is fundamental for social reintegration and quality of life improvement. Wheelchairs with a seat stabilization system for moving through inclined terrain can provide greater comfort and safety to the user. Adding low-cost functionalities to wheelchairs is essential to make them more accessible to people, therefore, this paper provides a design method of a new seat stabilization system applied to low-cost wheelchairs. [ABSTRACT FROM AUTHOR]

Accurate representation of spinal geometry is necessary in biomechanical modelling to properly understand the function of the spine. The objective of this study was to create a large database of image-derived digital spine surface models for geometric studies and computational biomechanics investigation. Computed tomography scan data was acquired from 60 asymptomatic subjects (30 males and 30 females). Subjects ranged in age from 20 to 68 with equal numbers selected in each 10-year age bracket. Three-dimensional geometric surface models were generated for each subject’s spine. A series of distance measures were also computed for each vertebral body to assess variation in the population. Geometric measures were able to show the significant variation in vertebrae size and shape within the subject population and as a function of vertebral level, gender, and age. This database enables the biomechanical evaluation of the variation in spinal loads that occurs within the population due to geometry.

We consider interval geometric modeling of complex multi parametric systems having a set of parameters of different character. Some of the parameters may have interval indefiniteness. System information basis is incomplete one. The processed information depends on continuous, discrete and conventional data. Geometric model has a form of matrix and each element of it corresponds to some state of the system. Each state is described by interval function of continuous input and output parameters. The set of interval functions generates some discrete set of multidimensional surfaces in discrete space. We use this approach and our modeling algorithm to find predictive model of drape coefficient. The algorithm is based on linear approximation of numerical factors in factor spaces. Interval functions make it possible for us to vary some numerical factors within the given intervals. As an example, the interval model of fabric drape coefficient is found. Fabric thickness and closeness of texture are considered as input parameters.

To predict the cutting force in machining of SiCp/Al composites by ultrasonic elliptical vibration-assisted turning (UEVT) technology, a semi-empirical geometric model considering the deformation and friction characteristics in different deformation areas is established in this paper. During UEVT, the resistance force acting on cutting edge is divided into three parts according to different deformation zones: shear force, interface friction, and plowing force. The vibration characteristic functions are also coupled to the semi-empirical geometric model of cutting force. A three factor and four level orthogonal tests is implemented to verify the validity of geometric model, and the single factor cutting experiments are also conducted to evaluate the influence law of relevant parameter on cutting force. Experimental results show that the deviation between the calculated value of cutting force and measured average value is less than 17%, and the average deviation is 8.16%, which proved that the semi-empirical geometric model can effectively predict the cutting force of SiCp/Al composites during UEVT. In addition, the influence of cutting parameters and volume fraction on cutting force is discussed, which provides a theoretical guidance for the outstanding machinability of SiCp/Al composites in UEVT. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The cornea is a vital tissue of the human body. The health status of the cornea has a great impact on the quality life of person. There has been a great deal of research on the human cornea biomechancis. However, the difficulty in obtaining the human cornea has greatly limited the research of cornea biomechancis. Using finite element modelling has become a very effective and economical means for studying mechanical properties of human cornea. In this review, the geometrical and constitutive models of the cornea are summarised and analysed, respectively. Some factors affecting of the finite element calculation are discussed. In addition, prospects and challenges for the finite element model of the human cornea are presented. This review will be helpful to researchers performing studies in the relevant fields of human cornea finite element analysis.

The damage of the frog rail significantly affects the wear of the crossing rail and restricts the passing speed of the train. A geometric 3D modeling of the vehicle passing through the crossing center is particularly concerned with the cumulative wheel-rail contact of the traffic volume. The frog rail wear is simulated to obtain the dynamic change of the impact force of the wheel on the frog rail as the rail wears. By summarizing the existing experimental results of other scholars, it is clear that the important factors, that cause the damage of the frog rail, are vehicle load, friction coefficient, slip roll ratio and shear stress. This paper combines the theoretical analysis of mechanics and 3D simulation to obtain the position change of the wheel-rail contact point with the wear of the frog rail, and finally compares it with the actual measurement results. It can more accurately predict the area where the maximum damage occurs after a certain amount of traffic for a certain fixed model, the change of wheel-rail contact point at frog rail is simulated with the wear of each component. Through theoretical analysis, the main factors determining frog rail damage were determined. Then evaluate the possible damage area of the frog track and control the prediction range to 5-10 cm, which reduces the detection time and cost. The worst state of distraction will be detected in time to facilitate replacement or polishing. Through further research in this area, the service life of the frog rail can be predicted. [ABSTRACT FROM AUTHOR]

Palm vein-based biometric highlights its contactless acquisition, high precision, and user acceptance. However, the lack of publicly available databases with a large number of individuals challenges the continuous growth of this biometrics. In this context, the generation of synthetic images offers a promising solution to address this limitation and facilitate the evaluation of recognition algorithms. This paper introduces a geometric model for generating realistic synthetic palm vein images for the creation of large-scale databases without collecting personal information. The model parameters were obtained by characterizing the external and internal structures of the palm, enabling the description of the vascular networks using their most representative points. Generated intermediate points are connected using piecewise interpolation to derive the vascular network structure. We applied biological optimization principles based on Murray's law to calculate the network thickness. The vascular structure was fused with generated palmprint texture to obtain the final synthetic palm vein image. An extensive evaluation examines the similarity between real and synthetic samples using qualitative and quantitative metrics. The results show the effectiveness of our approach in generating realistic synthetic palm vein images; thereby, the proposed model can be used to develop large-scale datasets. [ABSTRACT FROM AUTHOR]

Copyright of Wool Textile Journal is the property of National Wool Textile Science & Technology Information Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Late-discovered developmental hip dysplasia deformities often necessitate complex surgical treatments and meticulous preoperative planning. The selection of osteotomies is contingent upon the patient's age and the specific structural deformity of the hip. In our anatomical hip model, derived from the data of a 12-year-old patient, we performed virtual osteotomies that are commonly recommended for such cases. We precisely constructed geometric models for various osteotomies, including the Dega, Pemberton, Tönnis, Ganz, Chiari pelvic, and Pauwels femoral osteotomies. We employed Autodesk Inventor for the finite element analysis of the hip joint and the corrective osteotomies. In comparing one-stage osteotomies, we noted that the Dega and Ganz pelvic osteotomies, especially when combined with the Pauwels femoral osteotomy, yielded the most favorable outcomes. These combinations led to enhanced femoral head coverage and reduced intra-articular pressure. Furthermore, we calculated the femoral head-to-acetabulum volume ratio for both the Dega and Pauwels osteotomies. The encouraging results we obtained advocate for the integration of finite element analysis in virtual osteotomies of the pelvis and femur as a preoperative tool in the management of developmental hip dysplasia. [ABSTRACT FROM AUTHOR]

The article presents a modified algorithm for automated formation of geometric model of ship hull surface. The use of developed algorithm for construction of NURBS-surfaces allows to decrease labor input in several times in comparison with the use of manual labor when modeling surfaces in standard shipbuilding modeling systems like Sea Solution, Rhino and others. On the basis of this algorithm a software application is created, implemented in HTML5, JavaScript. The application allows to solve problems of creating and displaying three-dimensional models of ship surfaces in a standard the Internet browser. The program allows you to quickly analyze variants of the geometry of the ship hull model by adjusting the initial data, which significantly increases the productivity of the designer. It is possible to export the formed NURBS-surface for use in other design systems, including ship hull construction modeling, stability calculations, hull shell cutting and other tasks.

One of the possible approaches in the formation of the geometric part of the finite-element model in the process of teaching students is the use of the language IronPython in SpaceClaim environment with the purpose of subsequent modeling on the platform ANSYS WorkBench. The comparative advantages of Design Modeler and SpaceClaim for such a problem are described. An example of using this approach in a real learning process is given.

One of the possible approaches to the formation of the optimization model of the underlay is the use of cellular objects. At the same time, the question of constructing geometric models of such objects is relevant. Code fragments and construction results for one variant of geometry in IronPython language in SpaceClaim environment to solve such a problem are given. A possible approach to solving the problem of forming boundary conditions changing in time and space is described.

Dealing with heterogeneity in leaf canopies when calculating light interception per species in a mixed canopy is a challenge. Goudriaan developed a computationally simple, though conceptually sophisticated, model for light interception in strip canopies, which can be reasonably represented as 'blocks', such as vineyards and crop rows. This model is widely used, but there is no independent verification of the model. Hence, we developed a comparison of light interception calculations with Goudriaan's model and with detailed spatially explicit three-dimensional functional–structural plant models (FSPM) of maize in which plant architecture can be represented explicitly. Two models were developed, one with small randomly oriented leaves in blocks, similar to Goudriaan's assumption, which we refer to as the intermediate model (IM), and another with a realistic representation of individual plants with stems and leaves having shape, orientation and so on, referred as FSPM. In IM and FSPM, light interception was calculated using ray tracing. In Goudriaan's model, the light extinction coefficient (k), including both its daily and seasonal average values, was generated using the FSPM. Correspondence between the three models was excellent in terms of light capture for different levels of crop height, leaf area and uniformity, with the difference less than 3.3 %. The results are strong support for the use of Goudriaan's summary model for calculating light interception in strip canopies. [ABSTRACT FROM AUTHOR]

In the process of urbanization, the design and planning of urban landscapes have become increasingly important. Aiming at the shortcomings of traditional urban planning models such as poor visual presentation and low error rate in landscape creation, this article utilized remote sensing technology to collect vegetation and building landscape data and used geographic information systems (GIS) to process and analyze the collected landscape data. With the help of analyzed data, a visualization model of urban three-dimensional (3D) landscape network was constructed using sensors and modeling techniques. Sensors were used to achieve visualization display and management of urban landscape network, enabling better development of urban 3D landscape visualization models. The user satisfaction rate of the sensor based 3D landscape visualization model was over 92.4% and the average error rate of landscape creation after 20 experiments was 3.9835%. Building a 3D urban landscape visualization model based on sensors could effectively improve user satisfaction with the model's visualization, provide better visualization services to users and help designers better create landscapes, improving the accuracy of landscape creation. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three‐harness twill woven composite (THT‐WC) is an advanced carbon fiber reinforced composite that compromises the mechanical behaviors in both longitudinal and latitudinal directions. To explore the further practical application, the structural characteristics and static mechanical behavior of the material were investigated in this article. X‐ray computerized tomography was adopted to obtain the mesostructure details and to capture the key characteristics. With the help of mesoscale information, the 2D and 3D geometric models were established in the form of representative volume elements (RVEs). Combined with voxel mesh generation technology, a finite element model was proposed based on a 3D geometric model where macroscopic mechanical properties of materials along different yarn directions were gained. To verify the simulated geometry and predicted mechanical properties, mesoscale geometric comparison and specimen tensile tests were performed. The results show that the geometric model established in this article can reasonably reflect the periodicity fluctuation of binder warp yarns and the randomness fluctuation of weft yarns. Compared with the experimental results, the relative error of stiffness in the weft direction of the RVE is 4.25%, and that in the warp direction is 5.33%. Highlights: The mechanical properties of THT‐WC were investigated experimentally.Meso‐scale reconstruction of THT‐WC was presented.A model to predict the mechanical properties of THT‐WC is established. [ABSTRACT FROM AUTHOR]

From a surgical point of view, quantification cannot always be achieved in the developmental deformity in hip joints, but finite element analysis can be a helpful tool to compare normal joint architecture with a dysplastic counterpart. CT scans from the normal right hip of an 8-year-old boy and the dysplastic left hip of a 12-year-old girl were used to construct our geometric models. In a three-dimensional model construction, distinctions were made between the cortical bone, trabecular bone, cartilage, and contact nonlinearities of the hip joint. The mathematical model incorporated the consideration of the linear elastic and isotropic properties of bony tissue in children, separately for the cortical bone, trabecular bone, and articular cartilage. Hexahedral elements were used in Autodesk Inventor software version 2022 ("Ren") for finite element analysis of the two hips in the boundary conditions of the single-leg stance. In the normal hip joint on the cartilaginous surfaces of the acetabulum, we found a kidney-shaped stress distribution in a 471,672 mm2 area. The measured contact pressure values were between 3.0 and 4.3 MPa. In the dysplastic pediatric hip joint on a patch of 205,272 mm2 contact area, the contact pressure values reached 8.5 MPa. Furthermore, the acetabulum/femur head volume ratio was 20% higher in the dysplastic hip joint. We believe that the knowledge gained from the normal and dysplastic pediatric hip joints can be used to develop surgical treatment methods and quantify and compare the efficiency of different surgical treatments used in children with hip dysplasia. [ABSTRACT FROM AUTHOR]

The commonly used DC coil wounded around the electromagnet winding skeleton, acts as the key electro‐magnetic conversion element, is formed by enameled wire with poor heat dissipation. The electric conductivity of the conductors will be greatly influenced by the high temperature generated from coil's internal heat, especially for long‐term work conditions. Thus, in order to calculate the DC coil's temperature accurately and effectively during the primary design process of the electromagnet, a novel temperature rise calculation method for the steady and transient is proposed in this paper. First, the geometric and resistance models of the enameled wire are established, according to the spatial arrangement and the resistance‐temperature characteristics. Secondly, the temperature rise of the electromagnet coil is calculated theoretically, based on the steady and transient heat dissipation equations. Thirdly, the Thermal‐Electric simulation model is established, which is used to simulate and analyze the temperature of the electromagnet coil changing with excitation voltage. Finally, a temperature rise test platform of the electromagnet coil is established, the steady and transient temperature rise under various conditions is measured. The temperature rise results of theoretical calculation, simulation and experiment show good agreement with each other. It gives significant guidelines to the design and optimization processes of such electromagnet DC coil. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The external gear pump, like any other hydraulic component, is vulnerable to failure, which may lead to downtime as well as the failure of other components linked to it, thereby causing production loss. Therefore, establishing a condition monitoring system is crucial in identifying failure at an early stage. Traditional condition monitoring approaches rely on experimental data that are collected by means of sensors. However, the sensors utilized in the experiments may have calibration issues, which lead to inaccurate measurements. The availability of experimental data is also limited as it is difficult and expensive to create and detect a fault in a component. Hence, it is essential to develop a simulation model that mimics the performance of the actual system. The data generated from the model can be utilized to create the data source required for automated condition monitoring. A new methodology based on a detailed geometric model for simulating the External Gear Pump is described and compared to two models analyzed in the authors' previous work, namely Schlosser's loss model and simple geometric model. In this paper, the three models are compared with experimental data and the method utilized for fault injection. Schlosser's loss model, as well as the detailed geometric model, are found to be suitable in terms of validation; however, the latter is a better candidate in terms of fault injection. Hence, the detailed geometric model can be implemented as a tool to generate the data source for condition monitoring applications. [ABSTRACT FROM AUTHOR]

Ultra-precision diamond milling (UPDM) provides a promising generation of high-quality surface up to sub-micrometric form accuracy and nanometric surface roughness. Prior to its machining process, the investigation on surface generation would be beneficial to achieve desired quality with reduced cost and boosted productivity. However, few studies discussed this issue so far. In this study, a theoretical and experimental investigation into surface generation was carried out in UPDM. Firstly, a geometric model was built up considering the material removal process between the milling tool and the workpiece. Secondly, surface generation process was elaborated according to the developed model. Finally, UPDM experiments were performed on a typical brass material at different cutting conditions and surface texture parameters were characterized according to ISO 25178-2. Autocorrelation function (ACF) analysis was employed for a detailed evaluation of surface generation. The results showed that the static factors (cutting parameters) as well as the dynamic factors (material effects and spindle vibration), which were associated with the cutting conditions, yielded a great influence on surface generation. Surface texture characterization indicated that there was a good consistence between simulation and experiment, demonstrating the feasibility of the proposed method. ACF analysis indicated that, with the increased feedrate/step ratio, surface generation approximately achieved a transition from the periodical surface (dominated by cutting residuals) to the random surface (determined by multiple components). Significantly, this study draws up a fundamental understanding toward surface generation in UPDM. [ABSTRACT FROM AUTHOR]

This paper seeks to investigate nonlinear out-of-plane mechanical behaviours of woven composite flexible skin (WCFS) through experimental and theoretical methods. Firstly, quasi-static experiments are carried out on rectangular WCFSs with different aspect ratios under uniform normal pressure to measure out-of-plane deformation and failure loads. Afterwards, a new three-parameter geometric model is presented to describe 3D geometry of pressurized WCFS, and thus, a nonlinear mechanical model is deduced for depicting the relationship between pressure and out-of-plane displacement. The application of the aforementioned models for experimental results shows that the new models have adequately and logically depicted deformation geometry and nonlinear mechanical characteristics. [ABSTRACT FROM AUTHOR]

A novel variable thickness scroll expander composed of involutes of circle with different base circle radii is proposed. The generating method of profile is discussed, the general equation of profile is given, and a series of geometric models of the variable thickness scroll expander are established. According to the established geometric model, the influence of control coefficient on the volume change of the variable thickness scroll expander is analyzed. In addition, the geometric models of the traditional equal constant thickness and variable thickness scroll expander are constructed, and the advantages and disadvantages of the geometric models are compared. The results show that the novel variable thickness scroll expander model not only has the advantages of the traditional variable thickness model, but also greatly reduces the amount of calculation. To a certain extent, it enriches the types of variable thickness scroll expanders and provides reference for the development of high-performance scroll expanders.

A catastrophic rockslide occurred on 7 February 2021 in Chamoli area in the high Himalaya. In the absence of field data, multiple satellites data of decade span have been used to investigate and understand the progressive destabilization of rockslide body. A 3D geometric model was developed using geospatial information about geology, terrain, and ice cover to understand the triggering mechanism. Several causes are uncovered as: the pronounced long-term change of land surface temperature facilitated local permafrost degradation and led to ice cover shrinking since 2010; the occurrence of ice avalanche nearby in 2016 accompanying with sidewall-to-bedrock fracturing enhanced the ice segregation beneath the rockslide body; and the development of side cracks in early February 2021 led to dropping of side support and percolating of surface water. Heavy precipitation several days before favoured the destabilization, top-corner cracks developing and top-side bergschrund breaking abruptly two days before, and ice strength reduction owing air temperature rising few hours before the event triggered finally the rockslide. The frequent disasters such as cloudburst, extreme precipitation, landslides, and snow avalanches responding to global warming and climate change in the Himalayan region needs immediate attention to the chain-like geohazards and collaborative observation with satellites and other platforms.

Current cognitive architectures are either working at the abstract, symbolic level, or the low, emergent level related to neural modeling. The best way to understand phenomena is to see, or imagine them, hence the need for a geometric model of mental processes. Geometric models should be based on an intermediate level of modeling that describe mental states in terms of features relevant from the first-person perspective but also linked to neural events. Concepts should be represented as geometrical objects that have sufficiently rich structures to show their properties and their relations to other concepts. The best way to create such geometrical representations of concepts is through the approximate description of the physical states of neural networks. The evolution of brain states is then represented as a trajectory linking successful concepts, and topological constraints on the shape of such trajectory define grammar and logic.

The common properties of images on a plane and a sphere are considered in the scientific works by scientists-designers of spherical mechanisms. This is due to the fact that the plane and the sphere share common geometric parameters. They include constancy at all points of the Gaussian curve, which has a zero value for a plane and a positive value for a sphere. Figures belonging to them can slide freely on both surfaces. With unlimited growth of the radius of the sphere, its limited section approaches the plane, and the spherical shape transforms into a plane. Thus, a loxodrome that crosses all meridians at a constant angle is transformed into a logarithmic spiral that intersects at a constant angle the radius vectors that come from the pole. The tooth profile of cylindrical gears is outlined by the involute of a circle. A spherical involute is used for the corresponding bevel gears. Other spherical curves are also known, which are analogs of flat ones. The formation of a cycloid and an involute of a circle are associated with the mutual rolling of a line segment with each of these figures. If the segment is fixed and the circle rolls along it, then the point of the circle describes the cycloid. In the case of a stationary circle along which a segment is rolled, the point of the segment will execute the involute. To move to the spherical analogs of these curves, it is necessary to replace the circle with a cone, and the straight line with a plane. The spherical prototype of the cycloid will be the trajectory of the point of the base of the cone, which rolls along the plane, that is, along the sweep of the cone. The sweep of a cone is a sector, the radius of the limiting circle of which is equal to the generating cone. If this sweep, like a section of a plane, is rolled around a fixed cone, when its top coincides with the center of the sector, then the point of the limiting radius of the sector will execute a spherical involute. This paper analytically implements these two motions and reports the parametric equations of the spherical analogs of the circle involute and the cycloid [ABSTRACT FROM AUTHOR]

Methods to assess ultrasound backscatter anisotropy from clinical array transducers have recently been developed. However, they do not provide information about the anisotropy of microstructural features of the specimens. This work develops a simple geometric model, referred to as the secant model, of backscatter coefficient anisotropy. Specifically, we evaluate anisotropy of the frequency dependence of the backscatter coefficient parameterized in terms of effective scatterer size. We assess the model in phantoms with known scattering sources and in a skeletal muscle, a well-known anisotropic tissue. We demonstrate that the secant model can determine the orientation of the anisotropic scatterers, as well as accurately determining effective scatterer sizes, and it may classify isotropic versus anisotropic scatterers. The secant model may find utility in monitoring disease progression as well as characterizing normal tissue architectures. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the development of modern industry, modern national defense and modern medical rehabilitation industry, bionic design and manufacturing technology is booming. This technology often takes various organisms and their tissues as research objects, imitating their geometric shapes, mechanical properties and other indicators, and then achieves reverse design and manufacture of various synthetic products, in which the effective bionics of geometric shapes, especially surface modeling technology, is a key part of it. OBJECTIVE: Taking the human knee joint as an example, this paper discussed the practical application technology of surface modeling, and established a digital model of the geometric anatomy of the human knee joint. It provided support for the research on the biomechanical properties of the knee joint, and at the same time provided an effective teaching and research model for the complex surface modeling of the bionic mechanism. METHODS: Using knee CT scan images and magnetic resonance imaging images, the point cloud data and approximation curves of bone tissue and soft tissue contours were obtained through medical image processing technology, respectively, and the knee joint entity models of bone tissue and soft tissue were reconstructed respectively. Finally, based on the 3D image registration technology, each soft tissue group was assembled on the bone tissue entity model to form the overall knee joint 3D model. RESULTS AND CONCLUSION: Through 3D medical imaging technology, a digital anatomical digital model of knee joint with complex geometric surfaces including various bone tissues and ligaments, meniscus, tendons and other major soft tissues was constructed. [ABSTRACT FROM AUTHOR]

The Z-level milling technology is one of the most often used finishing milling strategy in case of the CNC milling of the steep free form surfaces. A main spindle parallel end-milling cutter can be used with or without corner radius, and the depth of cut means the axis parallel distance between the tool paths. During the planning of machining process two main aspects should be considered: the productivity and the accuracy. The accuracy means macro and micro accuracy. In this article the surface roughness, as a part of micro accuracy, is investigated, and a geometric approach of its estimation is presented. The tool corner geometry, the depth of cut and the inclination of the surface are considered, and the critical inclination is introduced. The theoretical description of the surface roughness is compared with the results of milling tests. As concluded, the cusp height, as the geometric model of the surface roughness can be a good base of the estimation, but a detailed and case depend model is required. The results ensure a better selection of tool path parameters in CAM systems considering the properties of cutting tool and the surface. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a simplified analytical model for predicting nonlinear mechanical responses of flexible composite sheet (FCS) subjected to out-of-plane loading. New geometric model based on three-parameter exponential function is proposed to depict 3D funnel-like geometric shape of out-of-plane loaded FCS, and nonlinear constitutive model is then derived to describe the load-displacement curves of out-of-plane loaded FCS. Finally, model parameters are determined through the principle of minimum potential energy. In order to verify new models, out-of-plane loading tests are performed on PWF (plain woven fabric) polyester reinforced HNR (hydrogenated nitrile rubber) composite sheets with three length-width ratios of 1, 2 and 3, and the predictions agree well with the experiments, demonstrating the practical and effective use of the proposed model. [ABSTRACT FROM AUTHOR]

AimsTraditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data.MethodsWe analyzed the FOs measured on AP hip and pelvis radiographs in a prospective consecutive series of 55 patients undergoing unilateral primary THA for hip osteoarthritis. To determine sample size, a power analysis was performed. Patients’ position and X-ray beam setting followed a standardized protocol to achieve reproducible projections. All images were calibrated with the KingMark calibration system. In addition, a geometric model was created to evaluate both the effects of leg position (rotation and abduction/adduction) and the effects of X-ray source position on FO measurement.ResultsThe mean FOs measured on AP hip and pelvis radiographs were 38.0 mm (SD 6.4) and 36.6 mm (SD 6.3) (p < 0.001), respectively. Radiological view had a smaller effect on FO measurement than inaccurate leg positioning. The model showed a non-linear relationship between projected FO and femoral neck orientation; at 30° external neck rotation (with reference to the detector plane), a true FO of 40 mm was underestimated by up to 20% (7.8 mm). With a neutral to mild external neck rotation (≤ 15°), the underestimation was less than 7% (2.7 mm). The effect of abduction and adduction was negligible.ConclusionFor routine THA templating, an AP pelvis radiograph remains the gold standard. Only patients with femoral neck malrotation > 15° on the AP pelvis view, e.g. due to external rotation contracture, should receive further imaging. Options include an additional AP hip view with elevation of the entire affected hip to align the femoral neck more parallel to the detector, or a CT scan in more severe cases.Cite this article: Bone Jt Open 2022;3(10):795–803.

Three-dimensional frequency selective fabric, based on textile or textile composite materials, is formed by adding another dimension in the longitude along the two-dimensional (2D) plane, and has the characteristics of miniaturization and multi-resonant frequency compared to the traditional 2D frequency selective fabric. In this paper, tunable three-dimensional frequency selective fabric (3D TFSF) forming a U-shaped array is proposed. The U-shaped unit is composed of two velvets and a dipole at the bottom. Through analysis of the physical samples, the geometric model of the 3D TFSF stretched along the x -axis and the y -axis during the stretching process was established. The velvets of the 3D TFSF were studied in both oblique and upright states during stretching. The 3D TFSF has good tunability, while the velvets remain upright when stretched, and it has the characteristics of stable resonance frequency under small strain and adjustable resonance frequency under large strain. By stretching, because the shape and size of the U-shaped conductive units can be changed, the equivalent inductance (L) and capacitance (C) of 3D TFSF can change during stretching to realize the tuning of resonant frequency. The 3D TFSF offers more design freedom and possibilities. Significant effects of wave absorption or selective filtering by the periodic structure can be achieved by regulating the structural parameters and material parameters together. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)