All-optical computing is an emerging information processing technology. As a cutting-edge technology in the field of photonics, it effectively leverages the unique advantages of photons to achieve rapid computation. However, the lack of a fully functional and programmable design has slowed the progress of this type of optical computing system, especially in optical logic computing. In this paper, we design and propose a programmable photonic logic array based on all-optical computing methods. By efficiently combining on-chip photonic devices such as micro-ring resonators, we have realized a complete set of reconfigurable all-optical logic computation functions, including basic logic such as IS&NOT, AND, and OR, as well as combined logic, such as XOR and XNOR. To the best of our knowledge, the proposed architecture not only introduces three structurally similar standard logic units but also allows for their multiple-level cascading to form a large-scale photonic logic array, enabling multifunctional logic computation. Furthermore, using two independent wavelengths to represent the high and low levels of logic can effectively reduce cross-talk and overlap between signals, decreasing the dependence on the strength of the optical signal and the decision threshold. Simulation results by Photonic Integrated Circuit Simulator (INTERCONNECT) demonstrate the effectiveness and feasibility of the proposed programmable photonic logic array.
Ovidiu ANTONESCU, Liviu UNGUREANU, Carmen Elisabeta RADU
et al.
In this paper is presented a topological structure and geometrical analysis for two
parallel manipulators types, referring to the calculation of mobility (degree of freedom) of these
complex mechanisms. It is used a new formula to calculate the mobility according to the number of
linear actuators which are considered having identical functions.
Yuriy M. Pleskachevsky, Eduard I. Starovoitov, Denis V. Leonenko
The effect of a homogeneous temperature field on the frequencies of natural oscillations of a circular sandwich plate is investigated. The hypothesis of a broken line is used as a kinematic one: for identical high-strength thin load-bearing layers, the Kirchhoff hypothesis; for a light incompressible thicker filler, the Timoshenko hypothesis on the straightness and incompressibility of a deformed normal. The differential equations of the transverse vibrations of the plate are obtained by the variational method. The desired functions are plate deflection and displacement in the filler. The analytical solution of the initial boundary value problem is constructed by decomposing into a series according to a system of proper orthonormal functions with hinged support or sealing of the plate contour. Calculation formulas for displacements are given. A numerical parametric analysis is carried out for the dependence of the oscillation frequencies of the plate on the materials of the bearing layers and temperature.
Yuma ADACHI, Takashi SHINOHARA, Tetsuya AKAGI
et al.
In Japan, where earthquakes occur frequently, aging infrastructure such as bridges, chimneys, power lines and tunnels have become very severe concern. Aging infrastructure is extremely dangerous as it has possibility to collapse due to earthquake shaking. Therefore, it is necessary to find a dangerous point in infrastructures immediately to prevent accident. Inspection was mostly carried out by inspector climbing the attached ladders. However, the inspection climbing the ladder becomes dangerous, because it uses uncertain ladder and unpredictable weather and conditions occur. Based on the situation, the automatic ladder climbing inspection robot that can climb up and down the ladder by using flexible robot arms without giving damage to the ladder was developed in the previous study. The previous flexible robot arm that consists of three Extension type Flexible Pneumatic Actuators (EFPAs) that can extend about 2.5 times from its original length. In this study, as assuming investigations in hazardous environments where toxic / flammable gas exit or inside of a nuclear reactor, a ladder climbing inspection robot with horizontal mobile function was proposed and tested. The theoretical estimation for ladder climbing up motion of the robot based on the analytical model was carried out. As a result, it was confirmed that the tested robot could climb up the ladder, although only slightly. Also, the driving tests using the tested robot for ladder climbing down motion and horizontal mobile motion were also carried out. As a result, it was confirmed that the tested robot could realize both vertical and horizontal movements.
Jaco Verster, P. Roux, Fleckson Magweregwede
et al.
In recent years, transport-related accidents, notably those involving trackless mobile machinery (TMM), have consistently ranked among the top three causes of fatalities and injuries in the South African mining industry (SAMI) [1]. These accidents arise from a combination of mechanical and technical malfunctions, environmental factors, and human or machine operator errors. Remarkably, these incidents persist despite the existence of specific regulations, standards, and codes of practice for transportation and machinery. This paper introduces a digital twin framework for TMM, which employs a systems engineering approach combined with software tools and computational analysis. This framework aims to enhance the current regulations by offering a continuous, quantitative risk assessment. By modelling and detecting non-conformance and adverse vehicle interaction events, the framework provides a quantitative risk analysis that complements the prevailing qualitative methods reliant on historical data and operational experience. A case study conducted at the CSIR main campus in Pretoria showcases the potential of the TMM Digital Twin.
Increasing requirements for modern machines necessitates the use of new equipment and the improvement of existing equipment. Methods and techniques aimed at improving its operational and quality characteristics. One of the areas of improvement is the method of surface plastic deformation, which qualitatively affects the overall reliability of the product. However, surface plastic deformation does not allow for the development of a schematic diagram and a general-purpose device that can be used to strengthen a wide range of agricultural machinery parts. Differences in the physical and mechanical properties of the materials of manufactured parts, their weight, dimensions, longitudinal and transverse stiffness, condition or position, hardening process, type of production and other factors in each specific case force designers and technologists to find reasonable options for designing new devices for processing parts by surface plastic deformation for ensuring high technical and economic indicators. Therefore, the development of surface plastic deformation devices and the improvement of existing equipment are urgent scientific and engineering tasks. The introduction of modern methods and tools in the development of mechanical engineering ensures an increase in the reliability of parts and products in general, as well as a reduction in the cost of production. This article describes the compaction of metal powders as a technological operation, as a result of which powder blanks are formed. The equipment for vibropressing of powder blanks is considered and compared. Technical processes of basic vibration and vibration impact are presented. The methods and schemes of implementation of vibropressing of powder materials are demonstrated. The classification of vibro-compaction processes according to the characteristics of vibration and vibration modes is analyzed.
L. M. Medina Uzcátegui, Carmen Müller-Karger Pereda, Euro Casanova Medina
The “Virtual Rotor Kit (VRK) Project” is a lightweight and standalone application developed in response to the challenges posed by the COVID-19 outbreak in the field of rotating machinery dynamics. This alternative emulates a rotor test rig, enabling virtual balancing tests on a single-plane rotor and offering students a comprehensive learning experience that simulates on-site balancing. The Virtual Rotor Kit utilizes a three-dimensional model based on a well-known rotor test rig widely used in educational and research settings. To simulate the dynamics of the rotor test rig, the application employs PyChrono, a dedicated Python library that wraps Chrono, a validated open-source multi-physics simulation engine. A detailed usability assessment involving 41 senior mechanical engineering students yielded promising results, indicating the Virtual Rotor Kit’s potential to enhance comprehension of vibration phenomena in unbalanced rotating machines. Despite revealing certain issues related to the graphical user interface and the application's execution time, three defined achievement indicators demonstrated positive outcomes for a virtual balancing laboratory experience using the Virtual Rotor Kit application. By focusing on the dynamic behavior of a rotor test rig instead of simulating a specific laboratory experience, the application offers instructors greater flexibility in developing learning experiences. Unlike other virtual testbeds, the Virtual Rotor Kit allows students to conduct both steady-state and transient experiments, offering a comprehensive understanding of rotating machinery dynamics. Additionally, the application is distributed under the BSD-3 license and can serve as a complement to on-site laboratory experiences. The results presented in this study inspire further research and development to enhance its efficacy.
Monica Sileo, Domenico Daniele Bloisi, Francesco Pierri
Robots allow industrial manufacturers to speed up production and to increase the product’s quality. This paper deals with the grasping of partially known industrial objects in an unstructured environment. The proposed approach consists of two main steps: (1) the generation of an object model, using multiple point clouds acquired by a depth camera from different points of view; (2) the alignment of the generated model with the current view of the object in order to detect the grasping pose. More specifically, the model is obtained by merging different point clouds with a registration procedure based on the iterative closest point (ICP) algorithm. Then, a grasping pose is placed on the model. Such a procedure only needs to be executed once, and it works even in the presence of objects only partially known or when a CAD model is not available. Finally, the current object view is aligned to the model and the final grasping pose is estimated. Quantitative experiments using a robot manipulator and three different real-world industrial objects were conducted to demonstrate the effectiveness of the proposed approach.
Chun-Ho Wu, Stephen Chi-Hung Ng, Keith Chun-Man Kwok
et al.
The proliferation of Industry 4.0 (I4.0) technologies has created a new manufacturing landscape for manufacturing, requiring that companies follow I4.0 trends to stay competitive. However, in this novel digital automated environment, these companies must also ensure that lean manufacturing principles are upheld. This study proposes a data-driven framework for analysing raw data across machines in manufacturing systems that can provide a comprehensive understanding of idle time and facilitate adjustments to reduce defect rates. This framework offers an alternative approach to improving manufacturing processes that involves utilising the power of I4.0 technologies in conjunction with lean manufacturing principles. This study’s examination of unprocessed data also provides guidance on improving legislation. The findings of this study provide direction for future research in the field of manufacturing and offer useful advice to businesses wishing to integrate I4.0 technologies into their operations.
Nikolaos Tsiamis, Loukia Efthymiou, Konstantinos P. Tsagarakis
The widespread use of drones in various fields has initiated a discussion on their cost-effectiveness and economic impact. This article analyzes in detail a methodological evaluation framework for the levelized cost of drone services for law enforcement purposes. Based on the data availability, we compared two vehicles: Phantom 4 Pro and Thunder-B. Moreover, we calculated their levelized costs per surveillance time and trip distance. Our approach helps users calculate the real costs of their vehicles’ services and produce equations for rapid estimations. We observed economies of scale for time and distance and showed differentiations per aircraft capacity. Furthermore, using the produced equations, we formulated a case study and compared the costs in a 4 km area constantly monitored by the two types of drones to support the best vehicle selection. We found that the Phantom 4 Pro costs less than the Thunder-B drone, for example. Thus, we demonstrate how, by applying this methodology beforehand, decision makers can select the most appropriate vehicle for their needs based on cost. Cost research estimations will improve UAV use and will help policymakers include UAV technology in crime prevention programs, especially when more data are available.
Hydrophilicity is one of the most vital characteristics of titanium (Ti) implants. Surface structure design is a powerful and efficient strategy for improving the intrinsic hydrophilic ability of Ti implants. Existing research has focused on experimental exploration, and hence, a reliable numerical model is needed for surface structure design and corresponding hydrophilicity prediction. To address this challenge, we proposed a numerical model to analyze the droplet dynamics on Ti surfaces with specific microstructures designed through the lattice Boltzmann method (LBM). In this work, a Shan-Chen (SC) model was applied in the simulations. We simulated droplets spreading on smooth and micropillar surfaces with various wettability and provided a comprehensive discussion of the edge locations, contact line, droplet height, contact area, surface free energy, and forces to reveal more details and mechanisms. To better tune and control the surface hydrophilicity, we investigated the effects of micropillar geometric sizes (pillar width a, height h, and pitch b) on hydrophilicity via single factor analysis and the response surface method (RSM). The results show that the hydrophilicity initially increases and then decreases with an increasing a, increases with an increasing h, and decreases with an increasing d. In addition, the interaction effects of a-d and h-d are significant. The optimization validation of the RSM also demonstrates the accuracy of our lattice Boltzmann (LB) model with an error of 0.687%. Here, we defined a dimensionless parameter ξ to integrate the geometric parameters and denote the surface roughness. The hydrophilicity of Ti surfaces improves with an increasing surface roughness. In addition, the effect of the microstructure geometry shape was investigated under the same value of surface roughness. Surfaces with micropillars show the best hydrophilicity. Moreover, this study is expected to provide an accurate and reliable LB model for predicting and enhancing the intrinsic hydrophilicity of Ti surfaces via specific microstructure and roughness designs.
Cr(VI)-based compounds pollution have attracted global concern due to serious harm to humans and environment. Hence, it is crucial to exploit an effective technique to eliminate Cr(VI) in water. Herein, we in-situ grown BiOI on graphitic carbon nitride to prepare the BiOI/g-C3N4 (BCN) direct Z-scheme heterojunction by solid phase engineering method at room temperature. Experimental result shown the photocatalytic activity of pure BiOI were obviously enhanced by constructing Z-scheme BCN heterostructure, and BCN-3 heterostructure exhibited the optimal photocatalytic degradation of RhB with 98% yield for 2.5 h and reduction of Cr(VI) with more than 99% yield for 1.5 h at pH = 2. Stability test shows BCN-3 still kept more than 98% reduction efficiency after 6 cycles. In addition, we also studied the reduction mechanism that shown the ·O2− radicals essentially helped to reduce the Cr(VI) in aqueous solution under illumination, verified the direct Z-scheme charge transfer path by X-ray photoelectron spectroscopy (XPS) and the free radical trapping experiment. The work open a new way for rationally designing photocatalyst heterostructure to reduce Cr(VI) to Cr(III).