Image smoothing provides a fundamental operation for image processing, with a broad spectrum of applications. It is a challenging task which requires global analysis on image patterns with scale ...awareness. Existing deep models for image smoothing are insufficiently efficient in global perception and multi-scale processing. This letter proposes a deep model with an efficient multi-scale fusion architecture and a series of global processing blocks. The architecture enhances multi-scale feature flow by incorporating features of different scales into both the encoder and decoder blocks of a U-shape network, with multi-scale feature fusion modules inserted between the encoder and the decoder. The global processing blocks leverage the multi-axis processing mechanism to achieve joint local and global perception. Benefiting from these two key designs, our proposed model enjoys superiority in both smoothing performance and computational complexity, as demonstrated in the experiments on two benchmark datasets.
•Proposed a method for multi-axis random vibration topology optimization.•Enhancing vibration resistance and extending life during the topology phase.•Prompting the structure to add load-bearing ...paths to resist random vibration loads.•Guiding the topology towards forming a vibration-resistant structure.•Expanding HCA into the field of random vibration performance topology optimization.
Considering the lack of effective solutions for multi-axis random vibration topology optimization problems, and recognizing that multi-axis random vibration excitation is the most common loading conditions experienced by structures during their operational life, this paper proposes a multi-objective topology optimization method for multi-axis random vibration. By combining Hybrid Cellular Automata (HCA) and Analytic Hierarchy Process (AHP), this method aims to enhance the vibration resistance of structures and extend their fatigue life during the topology optimization phase. To validate the effectiveness and engineering practicality of this method, two engineering cases were designed: a cantilever beam case and an automotive steering knuckle case. Multi-objective topology optimization were conducted with objectives including mass, stiffness, and vibration intensity metric (root-mean-square stress). The two cases demonstrate that the control group's topology model exhibits weaker resistance to random vibrations and shorter fatigue life. In contrast, the validation group's topology model introduces an additional load path near the excitation point, effectively dissipating the impact of vibration excitation. This enhances the structure's vibration resistance and significantly extends its fatigue life.
This short communication article critically reviews the modern trends in advanced filament winding machinery and filament wound composite pressure vessels (CPVs) and their potential applications. ...Firstly, it explores the historical development and advancements in filament winding machinery, which is essential to understand and assess the future state-of-the-art filament winding technique. Secondly, the classification of CPVs is further elucidated concentrating on composition, operating pressure, liner material, and load-bearing capability. It is classified that Type I, II, III, IV, and V of CPVs have been introduced and developed from all-metal to all-composite construction, which significantly reduces the weight of 75% to all-metallic pressure vessels. Thirdly, commercial and potential applications of CPVs have been introduced. Finally, this article provides an outlook on opportunities and challenges of advanced filament winding machinery and CPVs, which gains new insights into integrated design, manufacturing, and performance evaluation on CPVs with artificial intelligence (AI), digitalization, and visualization techniques.
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•The state-of-the-art of filament winding machinery and composite pressure vessels (CPVs) are reviewed.•Advanced multi-axis filament winding machineries are compared.•Classification of CPVs with type I, II, III, IV and V is evaluated.•Opportunities and challenges of advanced filament winding machinery and CPVs are discussed.
Not only is it important to know how large the overall change in vibration should be for occupants to perceive an improvement in comfort, but also how large this change should be in specific ...frequency bands. Relative difference thresholds (RDT) of primary (0.5-4 Hz) and secondary (9-80 Hz) ride are estimated for 14 automotive engineers seated in a vehicle on a 4-poster test rig over two roads. Resulting stimuli differed in magnitude and spectral shape. The median RDTs estimated for primary and secondary ride were 16.68% and 13.82% on the smooth road, and 9.50% and 24.67% over the rough road. Statistically significant differences were found in the medians of the RDTs between (1) primary and secondary ride on the two roads and (2) the two roads for changes in the primary and secondary ride, suggesting that Weber's law does not hold.
•A singularized geometrical parameter model is constructed to avoid the problems of indefinite equation and posture non-solution.•The modeling error of the Jacobian model is considered and ...compensated for the obtained geometric parameter.•An error predictive evaluation method is given to achieve optimal error compensation.•The precise Jacobi correction method is appliable for a wide use in multi-axis mechanisms.
The Jacobian model is a prevalent tool for error compensation in multi-axis parallel mechanisms. However, discrepancies between the model's nominal and actual geometrical parameters, combined with equivalent replacements and high-order rounding in the modeling process, lead to equation solving challenges and modeling errors. These inaccuracies result in residual errors in the Jacobian model compensation. To address these problems, this paper proposes an optimal Jacobian correction approach. This is based on a geometrical parameter singularized Jacobian correction model, and a module for the evaluation of coupling errors for multi-axis parallel mechanisms was incorporated. Instead of relying on iterative processes, a singularized geometrical error solution method (SESM) was developed. Through this method, precise derivation of the Jacobian correction parameters is ensured, effectively addressing the indefinite equation challenge and partial posture non-solution problem. Moreover, modeling errors resulting from equivalent infinitesimal replacements and the overlooking of high-order minor values are compensated for by the SESM. It was observed that varying singularized geometrical parameters in the Jacobian model can produce different coupling effects and compensation outcomes. Therefore, a sensitivity-based error predictive evaluation method (EPEM) was introduced. By this method, the optimal correction parameter of the Jacobian model across the entire workspace is identified, ensuring precise pose error compensation. The proposed method was validated using a three-axis parallel mechanism. Through these tests, its superior efficacy was revealed. In comparison to the traditional uncorrected Jacobian compensation, reductions in position and orientation errors by 64.93% and 55.29%, respectively, were achieved. This method provides a new approach for error modeling, equation solving, and parameter correction for multi-axis mechanism error compensation and precision equipment development.
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While multi-axis additive manufacturing is found to be a good solution to the inherent limitations of conventional 2.5D additive manufacturing, it is a much more sophisticated process. Among ...different existing multi-axis process planning algorithms, we are interested in those based on a scalar field, in which print slices are the iso-surfaces of a scalar field embedded in the 3D model. In this paper, we propose a partitioned-based print sequence planning algorithm and an adaptive slicing algorithm, which together determine a complete multi-axis printing process for an arbitrary solid model. The first algorithm iteratively subdivides the model into a set of components such that a collision-free print sequence can be established among the components. The second algorithm then extracts print slices from each component such that all these slices satisfy the self-support condition. Since an arbitrary model may not satisfy both the self-support and collision-free requirements, we also define certain critical printability rules at the beginning to check whether a given input model with its associated scalar field is printable. The generated print slices and print sequence by the proposed two algorithms are guaranteed to be printable. Furthermore, a shorter total fabrication time and a better surface quality are achieved. Physical experiments of four test models are performed on a homebuilt multi-axis FDM printer, whose results verify the capabilities of the proposed algorithms.
•A new print sequence planning algorithm based on partitioning for a 3D model associated with a scalar field is proposed.•An adaptive slicing paradigm for scalar field-based multi-axis printing is proposed to reduce the print time.•The developed algorithms guarantee printability, i.e., self-support and collision-free.•Computer simulations and physical experiments are performed on four models to validate the correctness of our algorithms.
This paper presents a general solution of precise position synchronous control for multi-axis servo systems. The control strategy to achieve high-precision motion is summarized in two main points: an ...adaptive-fuzzy friction compensator is adopted in the independent control loop of each axis to compensate the nonlinear friction, and then a method which combines global sliding mode control with two adjacent axes cross-coupling technology is proposed to minimize not only single-axis position error but also synchronous errors of all motion axes. At first, the adaptive fuzzy algorithm including dynamic model of the system is utilized to design a friction compensation controller. Next, to improve robustness of the multi-axis motion system against variation of motor parameters and external disturbances, global sliding mode control is introduced. In addition, the multi-axis synchronous control based on cross-coupling technology is elaborately designed via proportional-differential control law. The performance of the proposed control system is investigated through extensive simulations based on a popular motion platform. Furthermore, experimental study shows that the results successfully demonstrate the effectiveness of the proposed position synchronous control method for a general four-axis servo system.
This work presents a newly proposed multi-axis fast ED-milling approach for machining of diffuser-shaped film cooling holes on turbine blades. It aims to overcome the issues of alignment error and ...low overall efficiency raised by involving fast ED-drilling cooperated with sinking EDM. The new method fully utilizes the capabilities of fast ED-drilling and milling together with multi-axis simultaneous control functionality. The characteristics of this machining scheme are investigated, and an electrode wear compensation strategy was developed accordingly. Machining tests assure that the new method guarantees rather higher machining efficiency and comparable surface quality in contrast with layer-by-layer fast ED-milling.
In additive manufacturing, infill structures are commonly used to reduce the weight and cost of a solid part. Currently, most infill structure generation methods are based on the conventional ...2.5-axis printing configuration, which, although able to satisfy the self-supporting condition on the infills, suffer from the well-known stair-case effect on the finished surface and the need of extensive support for overhang features. In this paper, based on the emerging continuous multi-axis printing configuration, we present a new lattice infill structure generation algorithm, which is able to achieve the self-supporting condition for both the infills and the boundary surface of the part. The algorithm critically relies on the use of three mutually orthogonal geodesic distance fields that are embedded in the tetrahedral mesh of the solid model. The intersection between the iso-geodesic distance surfaces of these three geodesic distance fields naturally forms the desired lattice of infill structure, while the density of the infills can be conveniently controlled by adjusting the iso-values. The lattice infill pattern in each curved slicing layer is trimmed to conform to an Eulerian graph so to generate a continuous printing path, which can effectively reduce the retractions of the nozzle during the printing process. In addition, to cater to the collision-free requirement and to improve the printing efficiency, we also propose a printing sequence optimization algorithm for determining a collision-free order of printing of the connected lattice infills, which seeks to reduce the air-move length of the nozzle. Ample experiments in both computer simulation and physical printing are performed, and the results give a preliminary confirmation of the advantages of our methodology.
•A new curved-layer slicing method based on the 3D geodesic distance field is developed.•A new lattice infill structure generation method for multi-axis printing is proposed.•The generated infill structures are both interiorly self-supporting and exteriorly support-free.•A printing sequence optimization method is presented to reduce the air-move path length.
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