Assembly Model Research Articles

Simulating and Verifying a 2D/3D Laser Line Sensor Measurement Algorithm on CAD Models and Real Objects.

The increasing adoption of 2D/3D laser line sensors in industrial and research applications necessitates accurate and efficient simulation tools for tasks such as surface inspection, dimensional verification, and quality control. This paper presents a novel algorithm developed in MATLAB for simulating the measurements of any 2D/3D laser line sensor on STL CAD models. The algorithm uses a modified fast-ray triangular intersection method, addressing challenges such as overlapping triangles in assembly models and incorporating sensor resolution to ensure realistic simulations. Quantitative analysis shows a significant reduction in computation time, enhancing the practical utility of the algorithm. The simulation results exhibit a mean deviation of 0.42 mm when compared to real-world measurements. Notably, the algorithm effectively handles complex geometric features, such as holes and grooves, and offers flexibility in generating point cloud data in both local and global coordinate systems. This work not only reduces the need for physical prototyping, thereby contributing to sustainability, but also supports AI training by generating accurate synthetic data. Future work should aim to further optimize the simulation speed and explore noise modeling to enhance the realism of simulated measurements.

A New Multi-Axial Functional Stress Analysis Assessing the Longevity of a Ti-6Al-4V Dental Implant Abutment Screw.

This study investigates the impact of tightening torque (preload) and the friction coefficient on stress generation and fatigue resistance of a Ti-6Al-4V abutment screw with an internal hexagonal connection under dynamic multi-axial masticatory loads in high-cycle fatigue (HCF) conditions. A three-dimensional model of the implant-abutment assembly was simulated using ANSYS Workbench 16.2 computer aided engineering software with chewing forces ranging from 300 N to 1000 N, evaluated over 1.35 × 107 cycles, simulating 15 years of service. Results indicate that the healthy range of normal to maximal mastication forces (300-550 N) preserved the screw's structural integrity, while higher loads (≥800 N) exceeded the Ti-6Al-4V alloy's yield strength, indicating a risk of plastic deformation under extreme conditions. Stress peaked near the end of the occluding phase (206.5 ms), marking a critical temporal point for fatigue accumulation. Optimizing the friction coefficient (0.5 µ) and preload management improved stress distribution, minimized fatigue damage, and ensured joint stability. Masticatory forces up to 550 N were well within the abutment screw's capacity to sustain extended service life and maintain its elastic behavior.

Analyses of Off-Target Effects on Cardiac and Skeletal Muscles by Berberine, a Drug Used to Treat Cancers and Induce Weight Loss.

Previous reports from our laboratory describing the formation of myofibrils in cultured embryonic cardiac and skeletal muscle cells have proposed that myofibrillogenesis occurs in three steps of increasing protein organization: beginning with premyofibrils, followed by nascent myofibrils, and ending in mature myofibrils. Inhibitors of the ubiquitin proteasome system (UPS) prevented nascent myofibrils from progressing directly to mature myofibrils in cultured cardiac and skeletal muscle cells, supporting a three-step model of assembly in which some of the proteins in nascent myofibrils are proteolyzed to allow the assembly of mature myofibrils. Application of UPS inhibitors on cultured muscle cells suggests possible explanations for the off-target cardiac and skeletal muscle adverse effects of UPS drugs, which are used on cancer patients. Berberine, a plant derivative, has been used to treat various cancers, including multiple myelomas. In contrast to the use of UPS drugs, success was reported with Berberine in multiple myeloma patients with no off-target effects on their hearts. We have exposed cultured cardiac and skeletal muscle cells to Berberine, a ligase inhibitor of UHRF1 (ubiquitin-like with PHD and RING finger domains). Berberine inhibited myofibril assembly at the nascent myofibril stage in embryonic skeletal muscle cells but had no effect in the assembly of mature myofibrils in embryonic heart cells. RT-PCR experiments demonstrated Berberine inhibition of mRNA for muscle myosin II heavy chains but not for muscle actin mRNA in skeletal muscle cells. Berberine is also being used as a popular weight losing compound, because it is much cheaper and available without a prescription than the semaglutide containing weight losing drugs (Wegovy and Ozempic). In contrast to Berberine, semaglutide had no effects on myofibril assembly in culture assays for both cardiac and skeletal muscle cells. We postulate that analyses of cultured embryonic cardiac and skeletal muscle cells will provide a preclinical assay for the testing of novel cancer drugs with improved outcomes for patients, an important goal for cancer therapeutics.

Theoretical model construction and static performance analysis of multi-leaf journal foil bearings

Abstract Multi-leaf journal foil bearing (MLJFB) structures are complex, making performance prediction challenging, and the accurate prediction of gas film thickness and pressure distributions is crucial. In this study, COMSOL finite-element software was used to establish an initial foil assembly and structural deformation simulation model for an MLJFB with bump foils. Using MATLAB, a compressible gas lubrication model was established and solved using the finite volume method (FVM). Real-time data transfer between COMSOL and MATLAB enabled a fully coupled fluid-structure interaction simulation. This model meticulously accounts for the pre-tension force in the multi-leaf bearing assembly, contact friction between adjacent foils, and the interaction between the top foil and gas film pressure. The effects of journal movement distance, direction, and top foil overlapping ratio on the bearing capacity as well as the effects of different external load directions on the journal equilibrium position were analyzed based on this model. The results indicate that increasing the top foil overlapping ratio enhances the bearing capacity of the MLJFB. Furthermore, compared to the direction of the top foil overlap position, external loads applied in the direction of the top foil midpoint are more beneficial for bearing operational stability.

An outcome-defining role for the triple-helical domain in regulating collagen-I assembly

Collagens are the foundational component of diverse tissues, including skin, bone, cartilage, and basement membranes, and are the most abundant protein class in animals. The fibrillar collagens are large, complex, multidomain proteins, all containing the characteristic triple helix motif. The most prevalent collagens are heterotrimeric, meaning that cells express at least two distinctive procollagen polypeptides that must assemble into specific heterotrimer compositions. The molecular mechanisms ensuring correct heterotrimeric assemblies are poorly understood - even for the most common collagen, type-I. The longstanding paradigm is that assembly is controlled entirely by the ~30 kDa globular C-propeptide (C-Pro) domain. Still, this dominating model for procollagen assembly has left many questions unanswered. Here, we show that the C-Pro paradigm is incomplete. In addition to the critical role of the C-Pro domain in templating assembly, we find that the amino acid sequence near the C terminus of procollagen's triple-helical domain plays an essential role in defining procollagen assembly outcomes. These sequences near the C terminus of the triple-helical domain encode conformationally stabilizing features that ensure only desirable C-Pro-mediated trimeric templates are committed to irreversible triple-helix folding. Incorrect C-Pro trimer assemblies avoid commitment to triple-helix formation thanks to destabilizing features in the amino acid sequences of their triple helix. Incorrect C-Pro assemblies are consequently able to dissociate and search for new binding partners. These findings provide a distinctive perspective on the mechanism of procollagen assembly, revealing the molecular basis by which incorrect homotrimer assemblies are avoided and setting the stage for a deeper understanding of the biogenesis of this ubiquitous protein.

Mathematical Model of a Nonlinear Electromagnetic Circuit Based on the Modified Hamilton–Ostrogradsky Principle

This paper presents a mathematical model of a typical lumped-parameter electromagnetic assembly, which consists of two subassemblies: one includes a magnetic circuit and the other with selected elements of electric circuits. An interdisciplinary research approach is used, which assumes the use of a modified integral method based on the variational Hamilton–Ostrogradsky principle. The modification of the method is the extension of the Lagrange function by two components. The first one reflects the dissipation of electromagnetic energy in the system, while the second one reflects the effect of external non-potential forces acting on the electromagnetic system. This approach allows for the avoidance of the inconvenience of the classical theory, which assumes the decomposition of the entire integrated system into individual electrical subsystems. The state equations of the electromagnetic subassembly are presented solely on the basis of the energy approach, which in turn allows taking into account various latent motions in the system, because the equations are derived based on non-stationary constraints between subsystems. The adopted theory allows for the formulation of the model of the system in a vector form, which gives much more possibilities for the analysis of higher-order electromagnetic circuits. Another important advantage is that the state equations of the considered electrical object are given in Cauchy normal form. In this way, the equations can be integrated both explicitly and implicitly. The results of computer simulations are presented in graphical form, analysed, and discussed.

The Inhibitory Tendency of Calamagrostis epigejos and Solidago spp. Depends on the Successional Stage in Postindustrial Vegetation

ABSTRACTIn spontaneously vegetated postindustrial areas, we have limited knowledge of whether the known inhibitory tendencies of herbaceous species—Calamagrostis epigejos and Solidago spp.—vary across successional stages. Our study fills this knowledge gap to assess the inhibitory role of the invasive alien and expansive native species with known behavior from the literature. Specifically, we hypothesized: (i) there will be an inhibitory effect of these species on diversity across successional classes; (ii) the effect of a species will depend on the successional class due to abiotic requirements of plant communities in each successional class. We recorded vascular plant species and their abundance across 400 plots on post‐coal mine heaps in Upper Silesia, Poland. We classified spoil heaps into three successional classes (early‐stage; mid‐stage; late‐stage). We calculated plant community taxonomic, functional, and phylogenetic diversity and, using generalized linear mixed‐effects models, we estimated predictors of diversity indices across successional classes. While we found no limiting effects of these species on diversity indices across successional classes, the effects of a species depended on the successional stage. We found the impacts of Calamagrostis and Solidago cover on diversity indices in the mid‐successional stage. This implies that the early‐successional stage is controlled by the lottery (random) model of community assembly. However, in the mid‐successional stage, the competitive exploitation mechanism is evident, resulting in declines in diversity indices. Thus, the impacts of Calamagrostis and Solidago on diversity indices are evident in the mid‐successional stage.

Recovery of electrical power from exhaust air—role of vertical axis wind turbine

AbstractThis article explores the potential of regeneration of power from unnatural wind sources with the help of vertical axis wind turbines (VAWT). Researchers are searching for urban as well as industrial wind sources, which can be useful as the natural wind source to obtain electrical energy and utilize it. The wind sources considered here are the exhaust of the cooling or ventilation fans used in buildings, industries, and other places. The Darrieus VAWT extracts wind power from the exhaust air and reduces the power consumption of the concerned electrical drives. These uncommon energy sources have an inherent capability to recover a significant amount of energy without polluting the environment with less payback period. Recovered energy can be suitably converted into electrical energy and may be fed back to the power grid without any pollution, thus minimizing the total energy consumption of the building and reducing the cost operations. A detailed study of experimental models with different types of assembly and turbine models is conducted here with power outputs and operational behaviors on the existing systems. Various parameters and factors for existing and new applications are in detail that show the system has no negative impact on regular operation.

Research on compression failure criteria and characteristics of rock-concrete assemblies with rough interfaces

The combination of rock and concrete lining structures is a typical composite structure in the field of engineering. This study is based on the concept of equivalent strain energy and establishes a mechanical equivalent model for rock-concrete assemblies (RCA). Assuming that both rock and concrete satisfy the Mohr-Coulomb criterion, we derive the shear failure criterion of the equivalent model considering the roughness of the rock-concrete interface. The applicability of the model was verified through uniaxial and triaxial tests on eight different types of RCA structures. The research results indicate that an increase in confining pressure enhances the strength of the RCA. When the confining pressure reaches a certain value, concrete only experiences shear failure, and no macroscopic cracks appear in the rock. The structure of the RCA tends towards isotropy. As the height ratio of the RCA increases, its strength decreases. At minimal concrete height ratios, the strength of the RCA gradually approaches that of concrete. This study can provide valuable insights for designing and evaluating stability in engineering rock bodies within diverse geological environments.

Study on fuel management strategy for accident-tolerant fuel on in-pile irradiation test

Within the context of the long-term development plan of batch loading of accident-tolerant fuel assemblies, an equivalent physical model of lead test assemblies is established based on the requirements of radiation testing and the applicability of analysis software. The quantitative assessment has been conducted on the impacts of parameters including zirconium alloy cladding coating and pellet additives on reactivity of fuel assembly. Concurrently, the fuel management strategy is optimized in alignment with the irradiation test objectives of ATF assemblies, leading to the creation of an evaluation process tailored for ATF assembly loading pattern. Focusing on the irradiation of the lead test assemblies into a nuclear power plant in China, three-cycle nuclear reactor loading pattern are designed, which are taking into account the economic, safety, and irradiation testing goals of the nuclear power plant. Simultaneously, the neutronic characteristics are also evaluated, quantitatively. The results show that the established equivalent physical model can effectively represent the characteristics of the lead test assemblies. The loading patterns designed based on the Optimised fuel management strategy achieve the desired goals in terms of economy, safety and radiation test requirements. The designed loading pattern evaluation process and equivalent model analysis method in this work provide guidance for the subsequent engineering design and application of irradiation testing for lead test assemblies.

Simulation Model of One-Parameter Selective Assembly of Two Elements With Multivariate Set-Making

Analytical and simulation methods are used to model assembly processes and technological systems in order to determine and optimize their performance and functioning parameters. The first one, describes an object or process using mathematical relationships indirectly. Simulation modelling is one of the modern methods of production system experimental research, allowing to take the presence of various components in the system, nonlinear characteristics, non-determinism and dynamism of ongoing processes into account. This work is devoted to the simulation model development of the technological process of multivariate one-parameter selective assembly of two elements. Multivariate set-making is defined by generalized rules with a set of weights which elements are set the distribution of elements between sets of different types. Selectively assembled elements have parameters determined by the manufacturing stage, which are independent random variables with known probabilistic characteristics. It is assumed that the input-output relationship is linear with given coefficients, the set-making equations linking the numbers of selective groups and assembly sets are known. A simulation model of the assembly process was built in the GPSS World, which, in contrast to the known one, operates with multivariate set-making rules for the case of assembly of two elements. The model allows to determine the quantitative indicators of the assembly process, in particular, the probabilities of assembly set formation, work-in-progress and preliminary rejects. As an example, the process of multivariate set-making of two parts forming a precision engineering product is considered. The data of parts distributions of both types by selective groups before assembly are given, the technological process indicators are calculated. Based on the modelling results the advantages and disadvantages of the multivariate set-making process are outlined.

Second harmonic scattering reveals different orientational orders inside the hydrophobic cavity of hybrid nanotubes.

Second Harmonic Scattering (SHS) is a suitable technique to investigate the orientational correlations between molecules. This article explores the organization of different dye molecules adsorbed within the hydrophobic porosity of a hybrid organic-inorganic nanotube. Experimental polarization resolved SHS measurements highlight different orientational orders ranking from highly ordered and rigid organizations to disordered assemblies. Microscopic models of assemblies inside the pores are presented and discussed in the context of orientational correlation between the dye molecules. This work shows that the degree of order in the nanotube cavity follows the molecule's affinity within the porosity.

A Novel Passive Intermodulation Model of Coaxial Cable Assemblies With Distributed and Point-Source Nonlinearities

A Novel Passive Intermodulation Model of Coaxial Cable Assemblies With Distributed and Point-Source Nonlinearities

Phylogenetic structure and turnover between lowland and montane subtropical forests indicate differential community assembly processes, affected by successional stage and spatial gradients

Secondary forests represent an increasing proportion of global forest cover and offer a range of ecosystem services that are integral to environmental policy targets. Highly disturbed landscapes with temporal records of forest plant community composition offer key insights into the processes that shape plant communities as forests undergo secondary succession. We investigated patterns of plant community phylogenetic structure and phylogenetic beta diversity. Mean pairwise distance (MPD) and Mean Nearest Taxon Distance (MNTD) metrics were determined between co-occurring species within plant communities, in addition to phylogenetic beta diversity metrics relative to null models of random phylogenetic assembly. MPD and MNTD were compared between elevational and successional classes and modelled as products of intercommunity distance (metres) and forest community age (years). Phylogenetic nonmetric multidimensional scaling explored phylogenetic community structure between lowland and montane forest type in Hong Kong. We found that plant communities in secondary forests in Hong Kong exhibited patterns of increased basal phylogenetic clustering with increasing community elevation, while phylogenetic turnover was influenced by spatial and successional factors in lowland and montane forest. Our findings indicate differential community assembly in lowland compared to montane forest type in Hong Kong, as well as evidence for barriers to plant dispersal in secondary forest communities due to patterns of spatial phylogenetic clustering. Plant communities in montane forests were found to be phylogenetically distinct from lowland forest plant communities. Patterns of spatial phylogenetic clustering may suggest significant dispersal or post-dispersal processes causing the clustering of related species at fine spatial scales, while phylogenetic turnover with increasing successional age may indicate compositional changes during the process of passive forest regeneration. Collectively, these results emphasize the need to investigate active pathways for rewilding dispersal limited late successional forest tree species in Hong Kong.

Development and verification of an MC/MOC two-step scheme for neutronic analysis of FCM-fueled micro gas-cooled reactor

Gas-cooled microreactors are known for compact designs, high thermal-to-electric efficiencies, long refueling cycles, and flexible deployment capabilities, representing a groundbreaking solution to address the energy requisites of special scenarios. Fully ceramic microencapsulated (FCM) fuel is widely used in gas-cooled microreactors, bringing challenges to neutronic analysis methods. In this paper, an Monte Carlo/Method of Characteristics (MC/MOC) two-step scheme is developed and verified based on the reference case. In this scheme, the continuous-energy Monte Carlo calculations are used for reference calculation and multi-group cross-section generation. The multi-group Monte Carlo calculations are used for multi-group cross-section verification and the MOC solver verification. Fuel multi-group cross-sections are generated with the explicit fuel assembly model by continuous-energy Monte Carlo calculations, and structure multi-group cross-sections are generated with the simplified core model by continuous-energy Monte Carlo calculations. The core calculations are conducted with the MOC calculations. For verification, parameters such as power distribution, neutron spectrum, and control devices worth will be compared. Core calculation results show that the relative errors of MOC results are within −329 pcm, ±5%, ±6%, and ± 2 % for Keff, power distribution, neutron spectrum, and control device worth, separately. Moreover, the computation cost of MOC is only 6.6 % of the reference computation cost. The figure of merit results show that the MC-MOC scheme exhibits improved computational efficiency for neutronic analysis of FCM-fueled micro gas-cooled reactor.

Measurement and optimization method for aero-engine rotors based on binocular multi-line laser sensing and virtual assembly

During the assembly of aero-engine rotors, eccentricity and tilt errors along the radial and axial direction result in uneven loading along the mating surface, which significantly impacts the operational lifespan of the rotor. This paper proposes a three-dimensional contour measurement system based on binocular multi-line laser sensing and conducts an aircraft engine rotor stacking virtual assembly technology system, to response the practical requirements of aircraft engine rotor unit production assembly engineering. We combine multi-line structured light active projection device with the binocular stereo vision model to construct the contour measurement system, which enhances the surface features of the projected object by adhering to the common constraint of structured line and stereo vision. Furthermore, the error propagation model for multi-stage rotor assembly to investigate the mechanism of error impact is established aiming to facilitate quantitative research on virtual assembly mechanisms. By manipulating the rotor phases and evaluating the coaxiality under various conditions, effective prediction of phase variation can be achieved, the multi-objective benchmark virtual assembly method based on the error propagation model of multi-stage rotor coaxiality is presented. The experimental results indicate that the proposed measurement system achieves the maximum disparity between the spatial data points procured by the proposed measurement system and the predetermined value of 2.1 μm, and the maximum disparity between the target plane’s average movement distance and the preset value of 3.7 μm. The precision provided by this system effectively meets the objective of assembly phase optimization for multi-stage rotors. In the empirical experiment conducted on the three-stage rotors, both systems yielded identical optimized phases: 0° for the first-stage rotor, 270° for the second-stage rotor, and 120° for the third-stage rotor, thereby validating the efficacy of the proposed measurement and optimization method for aero-engine multi-stage rotors with virtual assembly.

Comparison of Ingestion of Different Size Hard and Soft Bodies Into a Representative Fan Assembly Model

Abstract Foreign matter ingestion into a jet engine is a significant hazard to the safety of aircraft. While soft body ingestions (i.e., bird or ice ingestions) have been extensively researched, the threat posed by uncrewed aircraft systems (UASs) is a more recent concern due to their recent rise in popularity and has not been thoroughly studied. To better understand the damage caused by UAS ingestions, it is crucial to examine the resulting ingestion damage in comparison to birds of similar mass. This analysis is an essential initial step in determining how previous knowledge regarding soft body ingestions can relate to this new threat. To properly analyze these ingestions, development of a model that accurately represents a fan assembly is essential. This model should include a fan, as well as representative boundary conditions for the ingestion, such as blade retention systems, nose cone, casing, and shaft. Items that are analyzed during the ingestion include the overall damage to the fan blades, average and peak forces imparted on the retention systems, impact loads with the casing, and transient loads due to impact on the shaft. The foreign object models used were experimentally validated at their nominal sizes to increase confidence in the results. Comparison of the effects of ingestion of UAS and birds of difference mass into the representative fan model are presented and discussed to gain a better understanding of the differences between soft and hard body ingestion.

Reconfigurable flexible assembly model and implementation for cross-category products

As the production orders are becoming multi-category and small-batch in the era of product personalization, these require frequent reconfiguration of reconfigurable flexible assembly system for cross-category products (RFAS-CCP). However, there is no suitable theoretical assembly model and systematic implementation framework. We first propose a five-element assembly model (FAM) for RFAS-CCP, i.e. product, process, resource, knowledge, and decision. The product, process, and resource element describe the objects, steps to be assembled, and the tools, fixtures, and other equipment used for assembly, respectively. The knowledge element is a form representation of various heterogeneous data, such as a knowledge graph. The decision element includes various assembly methods to achieve assembly automation, flexibility, and intelligence. Then, in order to standardize and easy the frequent reconfiguration process, we reorganize various decision methods into a three-phase systematic implementation framework according to which stage they are used: design, configuration, and operation phases. The design phase methods primarily design various assembly modules for a product family, forming an assembly resource library. The configuration phase methods primarily configure suitable assembly lines for a specific product in the product family. The operation phase methods monitor the status of the assembly line and ensures its stable operation through health management. Finally, the effectiveness and practicality of the proposed five-element assembly model and three-phase systematic implementation framework are experimented with a pressure reducing valve product.

Refined analysis of a supporting column assembly in a traditional Tibetan timber building and its limiting tilt angle before collapse

Traditional Tibetan architecture is an important part of the Chinese architecture. Many of the Tibetan structures are suffering from different types of damages after hundreds of years of service. The structural arrangement, types of damage and failure modes of these timber structures have been investigated on site. Tilting of structural members is found to be the most common type of damage. This paper studies the limiting inclination angle of a single-column supporting assembly of these structures before its collapse for proactive maintenance and restoration. A method to estimate the limiting tilt angle of the column is proposed based on the relationship between the lateral force, F, at the column head and the tilt angle, θ, of the column. Simplified analytical models of this column assembly in a traditional Tibetan timber building under in-plane and out-of-plane loadings respectively are proposed. The behavior of the constituting column foot joint, column-Queti joint and Queti-beam joint are analyzed in detail to obtain the global deformation and M-θ relationship of the column assembly under different loads. The F-θ relationship of the column assembly from the intact state to collapse is then obtained. A verified finite element model of the column assembly is adopted as reference to validate the performances of the proposed models throughout the loading process. Comparison of the F-θ curves obtained from the analytical models and the simulated results demonstrates the validity and accuracy of the proposed models. They may be adopted for a quick analysis of practical structures to estimate their limit states for health monitoring, maintenance and strengthening of structures.

Mechanical Characterization of Electrolyzer Membranes and Components Under Compression

Proton-exchange membrane (PEM) water electrolysis is a promising technology for producing clean hydrogen by electrochemically splitting water when paired with renewable energy sources. A major roadblock to improving electrolyzer durability is the mechanical degradation of the cell components, which requires an understanding of their mechanical response under device-relevant conditions. However, there is a lack of studies on the mechanical characterization of the PEM and other components, as well as and their interactions. This study aims to address this gap by using a custom-designed testing apparatus to investigate the mechanics of electrolyzer components in uniaxial compression at 25 and 80 °C. Findings show stress-strain response of components have a varying degree of nonlinearity owing to their distinct deformation mechanisms and morphologies, from porous structures to polymers. These results are used to develop an expression for compressive stress-strain response of Nafion membranes and then analyze the deformation of components under applied pressure by using a 1-D spring network model of cell assembly. This work provides a new understanding of mechanical responses of the electrolyzer membrane and cell components, which can help assess material design and cell assembly strategies for improved electrolyzer durability.