453 research outputs found
Self-healing composites: A review
Self-healing composites are composite materials capable of automatic recovery when damaged. They are inspired by biological systems such as the human skin which are naturally able to heal themselves. This paper reviews work on self-healing composites with a focus on capsule-based and vascular healing systems. Complementing previous survey articles, the paper provides an updated overview of the various self-healing concepts proposed over the past 15 years, and a comparative analysis of healing mechanisms and fabrication techniques for building capsules and vascular networks. Based on the analysis, factors that influence healing performance are presented to reveal key barriers and potential research directions
Building forecast maps of water quaůity for main rivers and canals in Tien Giang province, Vietnam
This study aims to enhance the mapping of forecast for water quality assessment in Mekong Delta provinces. The data from 32 sites from main rivers and canals in an area of around 2,482 km2 in Tien Giang Province, Vietnam, were used for calculation and mapping. The ArcGIS 9.3 software, Inverse Distance Weighting (IDW) interpolation method, hydrologic data, and water quality parameters in March (2010-2014) were applied to build the maps showing 2020 water quality predictions for main rivers and canals in Tien Giang Province. The estimation was based on the Water Quality Index (WQI) with 6 parameters such as pH, total suspended solid (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD), total nitrogen (T_N), and coliform. The results showed that water quality in the studied area in dry season will not be improved by the year 2020. The finding could be a scientific reference for the selection of effective approaches to improve water quality in main rivers and canals in Tien Giang Province
Robotized unplugging of a cylindrical peg press-fitted into a cylindrical hole
It is well accepted that remanufacturing, the returning of a product that has reached the end of its service life to its original condition, is economically and environmentally beneficial. Robotizing disassembly can make remanufacturing even more cost-effective by removing a substantial proportion of the labour costs associated with dismantling end-of-life products for subsequent processing. As unplugging of press-fitted components is a common operation in disassembly, it is appropriate to investigate how it can be robotized. This paper discusses an unplugging technique, twist-and-pull or twisting-pulling, to reduce the axial frictional resistance during the unplugging process and enable a robot to perform it easily. Through theoretical modelling, simulations, and experimental analysis, the paper explores the interaction between twisting, pulling and axial friction reduction during unplugging. Analysis of the experimental, simulation and theoretical results has confirmed that for a small radial interference, twist-and-pull reduces the axial friction and the maximum required unplugging force
Determine the source term of a two-dimensional heat equation
Let be a two-dimensional heat conduction body. We consider the
problem of determining the heat source with
be given inexactly and be unknown. The problem is nonlinear and ill-posed.
By a specific form of Fourier transforms, we shall show that the heat source is
determined uniquely by the minimum boundary condition and the temperature
distribution in at the initial time and at the final time .
Using the methods of Tikhonov's regularization and truncated integration, we
construct the regularized solutions. Numerical part is given.Comment: 18 page
Optimisation of Product Recovery Options in End-of-Life Product Disassembly by Robots
In a circular economy, strategies for product recovery, such as reuse, recycling, and remanufacturing, play an important role at the end of a product’s life. A sustainability model was developed to solve the problem of sequence-dependent robotic disassembly line balancing. This research aimed to assess the viability of the model, which was optimised using the Multi-Objective Bees Algorithm in a robotic disassembly setting. Two industrial gear pumps were used as case studies. Four objectives (maximising profit, energy savings, emissions reductions and minimising line imbalance) were set. Several product recovery scenarios were developed to find the best recovery plans for each component. An efficient metaheuristic, the Bees Algorithm, was used to find the best solution. The robotic disassembly plans were generated and assigned to robotic workstations simultaneously. Using the proposed sustainability model on end-of-life industrial gear pumps shows the applicability of the model to real-world problems. The Multi-Objective Bees Algorithm was able to find the best scenario for product recovery by assigning each component to recycling, reuse, remanufacturing, or disposal. The performance of the algorithm is consistent, producing a similar performance for all sustainable strategies. This study addresses issues that arise with product recovery options for end-of-life products and provides optimal solutions through case studies
Determination of the body force of a two-dimensional isotropic elastic body
Let represent a twodimensional isotropic elastic body. We
consider the problem of determining the body force whose form
with be given inexactly. The problem is
nonlinear and ill-posed. Using the Fourier transform, the methods of Tikhonov's
regularization and truncated integration, we construct a regularized solution
from the data given inexactly and derive the explicitly error estimate.
Numerical part is givenComment: 23 page
First Principles Prediction Unveils High-T Superconductivity in YScH Cage Structures
The quest for room-temperature superconductivity has been a long-standing
aspiration in the field of materials science, driving extensive research
efforts. In this work, we present a novel hydride, YScH, which is
stable at high pressure using a crystal structure prediction approach with a
fixed composition based on known structures. The discovered material is
crystalline in a hexagonal unit cell with space group P6/mmm and has a
fastinating structure consisting of two distinct cages: Sc@H and
Y@H. By conducting an extensive numerical investigation of lattice
dynamics, electron-phonon coupling, and solving the isotropic Eliashberg
equation, we have revealed a significant value of = 2.96 as the
underlying factor responsible for the remarkably high critical temperature
(T) of 306-332 K in YScH. As pressure increases, the T
remains above the ambient temperature. Our work has the potential to enhance
the existing understanding of high-temperature superconductors, with
implications for practical applications. The unique network of these cage-like
structures holds great promise for advancing our understanding of
high-temperature superconductors, potentially leading to innovative
applications
An Improved Bees Algorithm for Training Deep Recurrent Networks for Sentiment Classification
Recurrent neural networks (RNNs) are powerful tools for learning information from
temporal sequences. Designing an optimum deep RNN is difficult due to configuration and training
issues, such as vanishing and exploding gradients. In this paper, a novel metaheuristic optimisation
approach is proposed for training deep RNNs for the sentiment classification task. The approach
employs an enhanced Ternary Bees Algorithm (BA-3+), which operates for large dataset classification
problems by considering only three individual solutions in each iteration. BA-3+ combines the
collaborative search of three bees to find the optimal set of trainable parameters of the proposed deep
recurrent learning architecture. Local learning with exploitative search utilises the greedy selection
strategy. Stochastic gradient descent (SGD) learning with singular value decomposition (SVD) aims to
handle vanishing and exploding gradients of the decision parameters with the stabilisation strategy
of SVD. Global learning with explorative search achieves faster convergence without getting trapped
at local optima to find the optimal set of trainable parameters of the proposed deep recurrent learning
architecture. BA-3+ has been tested on the sentiment classification task to classify symmetric and
asymmetric distribution of the datasets from different domains, including Twitter, product reviews,
and movie reviews. Comparative results have been obtained for advanced deep language models and
Differential Evolution (DE) and Particle Swarm Optimization (PSO) algorithms. BA-3+ converged
to the global minimum faster than the DE and PSO algorithms, and it outperformed the SGD, DE,
and PSO algorithms for the Turkish and English datasets. The accuracy value and F1 measure have
improved at least with a 30–40% improvement than the standard SGD algorithm for all classification
datasets. Accuracy rates in the RNN model trained with BA-3+ ranged from 80% to 90%, while the
RNN trained with SGD was able to achieve between 50% and 60% for most datasets. The performance
of the RNN model with BA-3+ has as good as for Tree-LSTMs and Recursive Neural Tensor Networks
(RNTNs) language models, which achieved accuracy results of up to 90% for some datasets. The
improved accuracy and convergence results show that BA-3+ is an efficient, stable algorithm for the
complex classification task, and it can handle the vanishing and exploding gradients problem of
deep RNNs
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