Applied Sciences

20 pages, 7429 KiB

Open AccessArticle

Research on Path Planning of a Mining Inspection Robot in an Unstructured Environment Based on an Improved Rapidly Exploring Random Tree Algorithm

by Jingwen Wu, Liang Zhao and Ruixue Liu

Appl. Sci. 2024, 14(14), 6389; https://doi.org/10.3390/app14146389 - 22 Jul 2024

Cited by 1 | Viewed by 1172

Abstract

To ensure the safe production of mines, the intelligent trend of underground mining operations is gradually advancing. However, the operational environment of subterranean mining is intricate, making the conventional path-planning algorithm used by mining inspection robots frequently inadequate for real requirements. To safeguard [...] Read more.

To ensure the safe production of mines, the intelligent trend of underground mining operations is gradually advancing. However, the operational environment of subterranean mining is intricate, making the conventional path-planning algorithm used by mining inspection robots frequently inadequate for real requirements. To safeguard the mining inspection robot, targeting the problem of low search efficiency and path redundancy in the path planning of the existing rapidly exploring random tree (RRT) algorithm in the narrow and complex unstructured environment, a path-planning algorithm combining improved RRT and a probabilistic road map (PRM) is proposed. Initially, the target area is efficiently searched according to the fan-shaped goal orientation strategy and the adaptive step size expansion strategy. Subsequently, the PRM algorithm and the improved RRT algorithm are combined to reduce the redundant points of the planning path. Ultimately, considering the kinematics of the vehicle, the path is optimized by the third-order Bessel curve. The experimental simulation results show that the proposed path-planning algorithm has a higher success rate, smoother path, and shorter path length than other algorithms in complex underground mining environments, which proves the effectiveness of the proposed algorithm. Full article

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19 pages, 2015 KiB

Open AccessArticle

Peculiarities of Applying Partial Convolutions to the Computation of Reduced Numerical Convolutions

by Ibragim Suleimenov, Aruzhan Kadyrzhan, Dinara Matrassulova and Yelizaveta Vitulyova

Appl. Sci. 2024, 14(14), 6388; https://doi.org/10.3390/app14146388 - 22 Jul 2024

Cited by 2 | Viewed by 973

Abstract

A method is proposed that reduces the computation of the reduced digital convolution operation to a set of independent convolutions computed in Galois fields. The reduced digital convolution is understood as a modified convolution operation whose result is a function taking discrete values [...] Read more.

A method is proposed that reduces the computation of the reduced digital convolution operation to a set of independent convolutions computed in Galois fields. The reduced digital convolution is understood as a modified convolution operation whose result is a function taking discrete values in the same discrete scale as the original functions. The method is based on the use of partial convolutions, reduced to computing a modulo integer

q_{0}

, which is the product of several prime numbers:

q_{0} = p_{1} p_{2} \dots p_{n}

. It is shown that it is appropriate to use the expansion of the number

q_{0}

, to

q = p_{0} p_{1} p_{2} \dots p_{n}

, where

p_{0}

is an additional prime number, to compute the reduced digital convolution. This corresponds to the use of additional digits in the number system used to convert to partial convolutions. The inverse procedure, i.e., reducing the result of calculations modulo q to the result corresponding to calculations modulo

q_{0}

, is provided by the formula that used only integers proved in this paper. The possibilities of practical application of the obtained results are discussed. Full article

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19 pages, 859 KiB

Open AccessArticle

A Longitudinal Study on the Adoption of Cloud Computing in Micro, Small, and Medium Enterprises in Montenegro

by Ivana Ognjanović, Ramo Šendelj, Milica Daković-Tadić and Ines Kožuh

Appl. Sci. 2024, 14(14), 6387; https://doi.org/10.3390/app14146387 - 22 Jul 2024

Viewed by 2481

Abstract

In recent years, small and medium enterprises worldwide have increasingly adopted digital technologies and cloud computing. The pace of this digital transition has varied across countries, and the socioeconomic conditions during the pandemic have further accelerated the digitalization of enterprises. This situation calls [...] Read more.

In recent years, small and medium enterprises worldwide have increasingly adopted digital technologies and cloud computing. The pace of this digital transition has varied across countries, and the socioeconomic conditions during the pandemic have further accelerated the digitalization of enterprises. This situation calls for an examination of the reasons, benefits, and risks associated with enterprises adopting cloud computing in different settings. Our study aimed to collect longitudinal data from 71 Montenegrin micro, small, and medium enterprises. We conducted a repeated measurement study with two measurement periods: 2017 and 2023. The quantitative results were analyzed alongside qualitative data from a semi-structured interview (N = 15) conducted in 2023. The findings revealed substantial shifts in SME attitudes towards cloud computing, highlighting key catalysts and influencing factors such as security, technological accessibility, external expertise, effort expectations, privacy, social influence, perceived security and safety, ease of use, and usefulness. These factors were examined in the context of global digital innovation, the impact of the COVID-19 pandemic, and recent cyberattacks that disrupted national e-services in Montenegro for 3–9 months. The findings provide new insights into how enterprises can become more prepared to effectively use cloud computing. Full article

(This article belongs to the Special Issue Cloud Computing: Challenges, Application and Prospects)

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16 pages, 2741 KiB

Open AccessArticle

Composite Copolymer Beads Incorporating Red Mud for Water Amendment by Adsorption—Oxidation Processes

by Teodor Sandu, Elena Alina Olaru, Raul-Augustin Mitran, Andreea Miron, Sorin-Viorel Dolana, Anamaria Zaharia, Ana-Mihaela Gavrilă, Marinela-Victoria Dumitru, Anita-Laura Chiriac, Andrei Sârbu and Tanța-Verona Iordache

Appl. Sci. 2024, 14(14), 6386; https://doi.org/10.3390/app14146386 - 22 Jul 2024

Viewed by 1020

Abstract

We face significant environmental pollution problems due to various industries, such as the aluminum industry, which generates large amounts of red mud (RM) waste, or agriculture, in which case the use of pesticides creates huge water pollution problems. In this context, the present [...] Read more.

We face significant environmental pollution problems due to various industries, such as the aluminum industry, which generates large amounts of red mud (RM) waste, or agriculture, in which case the use of pesticides creates huge water pollution problems. In this context, the present study offers a better perspective to originally solve both environmental issues. Thus, the main target of the study referred to using RM waste as a filler for preparing composite copolymer beads. Thereafter, this can achieve significant removal of water pollutants due to their adsorption/oxidation characteristics. As evidenced by the changes in chemical structure and composition, thermal stability, morphology, and porosity, RM was homogenously incorporated in poly(acrylonitrile-co-acrylic acid) beads prepared by wet phase inversion. The final assessment for the removal of pesticides by adsorption and oxidation processes was proven successful. In this regard, 2,4-dichlorophenoxyacetic acid was chosen as a model pollutant, for which an adsorption capacity of 16.08 mg/g composite beads was achieved. Full article

(This article belongs to the Special Issue Pollution Control Chemistry II)

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Figure 1
(A). Chemical structure of 2,4-DCFA, with formula C8H6Cl2O3 and a molar mass of 221.04 g/mol; (B). schematic representation of the preparation process for composite beads with RM; (C). pictures of lyophilized series of beads with RM (1-RM, 2-RM, and 3-RM) and the control beads (1-Ref, 2-Ref, and 3-Ref) with diameters of 2–4 mm. Full article ">Figure 2
FTIR spectra of analyzed composite copolymer beads compared to RM alone and their corresponding precursor copolymer: (A) C1-based series; (B) C2-based series; (C) C3-based series. Full article ">Figure 3
Thermogravimetric analyses (A–C) and differential thermal analysis (D–F) of the composite copolymer beads and their corresponding references, compared to the precursor materials of RM alone and corresponding copolymers. Full article ">Figure 4
Micrographs of reference (top) and composite beads (bottom) taken at 50 µm scale: (A). section view and (B). surface view. Full article ">Figure 5
FTIR spectra of (A) 3-RM, 3-RM before and after adsorption (3-RM-Ads)/oxidation (3-RM-Ox) processes; (B) 3-RM after reconditioning from the two procedures (3-RM-R-Ads after adsorption and 3-RM-R-Ox after oxidation). Full article ">

19 pages, 7129 KiB

Open AccessArticle

Controller of Pneumatic Muscles Implemented in Active Seat Suspension

by Igor Maciejewski, Sebastian Pecolt, Andrzej Błażejewski, Tomasz Krzyzynski and Sebastian Glowinski

Appl. Sci. 2024, 14(14), 6385; https://doi.org/10.3390/app14146385 - 22 Jul 2024

Viewed by 973

Abstract

In this work, we present a study on seat suspension technology that integrates pneumatic muscles, marking a significant advancement in active vibration control. This innovative approach addresses the limitations of traditional suspension systems, providing enhanced comfort and adaptability. A key achievement is the [...] Read more.

In this work, we present a study on seat suspension technology that integrates pneumatic muscles, marking a significant advancement in active vibration control. This innovative approach addresses the limitations of traditional suspension systems, providing enhanced comfort and adaptability. A key achievement is the development of a mathematical model for controlling horizontal seat vibration, which serves as a valuable design tool for evaluating seat suspension under various conditions and control strategies. The creation of a custom microcontroller, benchmarked against a standard from National Instruments, highlights the practical applications of this research. Positive results suggest a promising future for this technology in industrial settings, where vibration reduction is critical. The system’s scalability and user-adjustable signal levels further enhance its potential for widespread industrial adoption. Full article

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18 pages, 1868 KiB

Open AccessArticle

Open-Pit Mining Area Extraction Using Multispectral Remote Sensing Images: A Deep Learning Extraction Method Based on Transformer

by Qinghua Qiao, Yanyue Li and Huaquan Lv

Appl. Sci. 2024, 14(14), 6384; https://doi.org/10.3390/app14146384 - 22 Jul 2024

Cited by 1 | Viewed by 1101

Abstract

In the era of remote sensing big data, the intelligent interpretation of remote sensing images is a key technology for mining the value of remote sensing big data and promoting a number of major applications, mainly including land cover classification and extraction. Among [...] Read more.

In the era of remote sensing big data, the intelligent interpretation of remote sensing images is a key technology for mining the value of remote sensing big data and promoting a number of major applications, mainly including land cover classification and extraction. Among these, the rapid extraction of open-pit mining areas plays a vital role in current practices for refined mineral resources development and management and ecological–environmental protection in China. However, existing methods are not accurate enough for classification, not fine enough for boundary extraction, and poor in terms of multi-scale adaptation. To address these issues, we propose a new semantic segmentation model based on Transformer, which is called Segmentation for Mine—SegMine—and consists of a Vision Transformer-based encoder and a lightweight attention mask decoder. The experimental results show that SegMine enhances the network’s ability to obtain local spatial detail information and improves the problem of disappearing small-scale object features and insufficient information expression. It also better preserves the boundary details of open-pit mining areas. Using the metrics of mIoU, precision, recall, and dice, experimental areas were selected for comparative analysis, and the results show that the new method is significantly better than six other existing major Transformer variants. Full article

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22 pages, 6169 KiB

Open AccessArticle

Design of Robust Broadband Frequency-Invariant Broadside Beampatterns for the Differential Loudspeaker Array

by Yankai Zhang, Hongjian Wei and Qiaoxi Zhu

Appl. Sci. 2024, 14(14), 6383; https://doi.org/10.3390/app14146383 - 22 Jul 2024

Cited by 1 | Viewed by 949

Abstract

The directional loudspeaker array has various applications due to its capability to direct sound generation towards the target listener and reduce noise pollution. Differential beamforming has recently been applied to the loudspeaker line array to produce a broadside frequency-invariant radiation pattern. However, the [...] Read more.

The directional loudspeaker array has various applications due to its capability to direct sound generation towards the target listener and reduce noise pollution. Differential beamforming has recently been applied to the loudspeaker line array to produce a broadside frequency-invariant radiation pattern. However, the existing methods cannot achieve a compromise between robustness and broadband frequency-invariant beampattern preservation. This paper proposed a robust broadband differential beamforming design to allow the loudspeaker line array to radiate broadside frequency-invariant radiation patterns with robustness. Specifically, we propose a method to determine the ideal broadside differential beampattern by combining multiple criteria, namely null positions, maximizing the directivity factor, and achieving a desired beampattern with equal sidelobes. We derive the above ideal broadside differential beampattern into the target beampattern in the modal domain. We propose a robust modal matching method with Tikhonov regularization to optimize the loudspeaker weights in the modal domain. Simulations and experiments show improved frequency-invariant broadside beamforming over the 250–4k Hz frequency range compared with the existing modal matching and null-constrained methods. Full article

(This article belongs to the Special Issue Noise Measurement, Acoustic Signal Processing and Noise Control)

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22 pages, 23375 KiB

Open AccessArticle

AnimalEnvNet: A Deep Reinforcement Learning Method for Constructing Animal Agents Using Multimodal Data Fusion

by Zhao Chen, Dianchang Wang, Feixiang Zhao, Lingnan Dai, Xinrong Zhao, Xian Jiang and Huaiqing Zhang

Appl. Sci. 2024, 14(14), 6382; https://doi.org/10.3390/app14146382 - 22 Jul 2024

Viewed by 1096

Abstract

Simulating animal movement has long been a central focus of study in the area of wildlife behaviour studies. Conventional modelling methods have difficulties in accurately representing changes over time and space in the data, and they generally do not effectively use telemetry data. [...] Read more.

Simulating animal movement has long been a central focus of study in the area of wildlife behaviour studies. Conventional modelling methods have difficulties in accurately representing changes over time and space in the data, and they generally do not effectively use telemetry data. Thus, this paper introduces a new and innovative deep reinforcement learning technique known as AnimalEnvNet. This approach combines historical trajectory data and remote sensing images to create an animal agent using deep reinforcement learning techniques. It overcomes the constraints of conventional modelling approaches. We selected pandas as the subject of our research and carried out research using GPS trajectory data, Google Earth images, and Sentinel-2A remote sensing images. The experimental findings indicate that AnimalEnvNet reaches convergence during supervised learning training, attaining a minimal mean absolute error (MAE) of 28.4 m in single-step prediction when compared to actual trajectories. During reinforcement learning training, the agent has the capability to replicate animal locomotion for a maximum of 12 iterations, while maintaining an error margin of 1000 m. This offers a novel approach and viewpoint for mimicking animal behaviour. Full article

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20 pages, 5975 KiB

Open AccessArticle

Research on the Reasonable Width of Coal Pillar Driving along Goaf under Thick Hard Roof

by Wei Gu, Dalong Xu, Zhenfei Han and Hao Zhang

Appl. Sci. 2024, 14(14), 6381; https://doi.org/10.3390/app14146381 - 22 Jul 2024

Cited by 1 | Viewed by 873

Abstract

There are fewer studies on the width of coal pillar retaining under a thick, hard roof. This paper takes the thick limestone roof in the 10110 working face of Jinniu Coal Mine as the background, taking the reasonable coal pillar width and its [...] Read more.

There are fewer studies on the width of coal pillar retaining under a thick, hard roof. This paper takes the thick limestone roof in the 10110 working face of Jinniu Coal Mine as the background, taking the reasonable coal pillar width and its stability control technology as research objectives. Taking the theoretical analysis and calculation, numerical simulation to study the stress distribution along goaf under different parameters of the roof cutting, the stress distribution of the roadway, and displacement of the surrounding rock under different coal pillar widths, finally examined through on-site industrial experiments. The results show that (1) the vertical stress along goaf shows a gradual decrease with the increase of the roof cutting height and angle; after considering the cost and the difficulty, the optimal height and angle are chosen to be 21 m and 15°; (2) the vertical peak stress of coal pillar decreases with the increase of the width, coal pillar is gradually transformed from the crushed state to the elastic state, the displacement of the roadway also decreases with the increase of the width of the pillar, and the width of the coal pillar is chosen to be 8.0 m after comprehensive analysis; (3) during the roadway excavation and working face mining, the deformation of the surrounding rock is in a reasonable range, and the anchors and bolts are in a good state of stress, which indicates that retaining 8 m coal pillar is a success. This paper also provides theoretical references and implications for coal pillar retaining in similar geological mining conditions. Full article

(This article belongs to the Section Civil Engineering)

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22 pages, 6251 KiB

Open AccessArticle

A New Adaptive Strategy for Enhancing the Stability of Isolated Grids through the Integration of Renewable Energy and V2G Management

by Edisson Villa-Ávila, Paul Arévalo, Danny Ochoa-Correa, Vinicio Iñiguez-Morán and Francisco Jurado

Appl. Sci. 2024, 14(14), 6380; https://doi.org/10.3390/app14146380 - 22 Jul 2024

Viewed by 1292

Abstract

The integration of renewable energy sources into isolated microgrids introduces significant power fluctuations due to their intermittent nature. This study addresses the need for advanced power smoothing methods to enhance the stability of isolated networks. An innovative adaptive strategy is presented, combining photovoltaic [...] Read more.

The integration of renewable energy sources into isolated microgrids introduces significant power fluctuations due to their intermittent nature. This study addresses the need for advanced power smoothing methods to enhance the stability of isolated networks. An innovative adaptive strategy is presented, combining photovoltaic solar generation with vehicle-to-grid technology, utilizing an enhanced adaptive moving average filter with fuzzy logic control. The primary objective is to dynamically optimize the time frame of the Li-ion battery energy storage system for immediate power stabilization, leveraging the high energy density and rapid response capabilities inherent in electric vehicle batteries. The methodology encompasses data acquisition from photovoltaic panels, definition of fuzzy logic control rules, and implementation of the proposed method within a computer-controlled system connected to a bidirectional three-phase inverter. Experimental results highlight the proposed method’s superiority over conventional moving averages and ramp-rate filters. Full article

(This article belongs to the Special Issue Vehicle-to-Grid Systems: The Trends and Smart Grid Interaction Technologies)

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17 pages, 14445 KiB

Open AccessArticle

Are Clinical Balance Measures Linked to Cycling Performance?

by Tasman Harris, Kevin Netto, Caitlin M. Hillier, Sharni Burgess and Simon M. Rosalie

Appl. Sci. 2024, 14(14), 6379; https://doi.org/10.3390/app14146379 - 22 Jul 2024

Viewed by 954

Abstract

Balance is paramount to safe and successful cycling, both in competition and recreation. Balance has been investigated in the return-to-cycling context, but its relationship to cycling performance is unknown. Our study aimed to analyse the relationship between balance, measured by common clinical balance [...] Read more.

Balance is paramount to safe and successful cycling, both in competition and recreation. Balance has been investigated in the return-to-cycling context, but its relationship to cycling performance is unknown. Our study aimed to analyse the relationship between balance, measured by common clinical balance tests, and cycling performance. Seven competitive cyclists participated in this cross-sectional correlational study. We collected field-based measures of cycling performance, including mean velocity, minimum and maximum velocity, mean corner speed, average lap time, and lean angle. Also, we measured balance via the balance error scoring system, the star excursion balance test, the lateral reach test, and the modified Bass test of dynamic balance. Strong correlations between cornering performance and cycling performance (r = 0.65–0.87, p < 0.01) were detected. Weak correlations between clinical balance tests and cycling performance (r = 0.33–0.53, p < 0.05) were observed. In conclusion, our study showed that improving cornering performance has the potential to improve overall cycling performance. We also found no clear correlations between our clinical balance tests and cycling performance. These weak correlations between postural control in standing and cycling performance suggest that standing balance and balancing during cycling are distinct motor control processes. Full article

(This article belongs to the Special Issue Exercise Physiology and Biomechanics in Human Health)

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16 pages, 6284 KiB

Open AccessArticle

Estimating Urban Traffic Safety and Analyzing Spatial Patterns through the Integration of City-Wide Near-Miss Data: A New York City Case Study

by Chuan Xu, Jingqin Gao, Fan Zuo and Kaan Ozbay

Appl. Sci. 2024, 14(14), 6378; https://doi.org/10.3390/app14146378 - 22 Jul 2024

Cited by 1 | Viewed by 1451

Abstract

City-wide near-miss data can be beneficial for traffic safety estimation. In this study, we evaluate urban traffic safety and examine spatial patterns by incorporating city-wide near-miss data (59,277 near-misses). Our methodology employs a grid-based method, the Empirical Bayes (EB) approach, and spatial analysis [...] Read more.

City-wide near-miss data can be beneficial for traffic safety estimation. In this study, we evaluate urban traffic safety and examine spatial patterns by incorporating city-wide near-miss data (59,277 near-misses). Our methodology employs a grid-based method, the Empirical Bayes (EB) approach, and spatial analysis tools including global Moran’s I and local Moran’s I. The study findings reveal that near-misses have the strongest correlation with observed crash frequency among all the variables studied. Interestingly, the ratio of near-misses to crashes is roughly estimated to be 1957:1, providing a potentially useful benchmark for urban areas. For other variables, an increased number of intersections and bus stops, along with a greater road length, contribute to a higher crash frequency. Conversely, residential and open-space land use rates show a negative correlation with crash frequency. Through spatial analysis, potential risk hotspots including roads linking bridges and tunnels, and avenues bustling with pedestrian activity, are highlighted. The study also identified negative local spatial correlations in crash frequencies, suggesting significant safety risk variations within relatively short distances. By mapping the differences between observed and predicted crash frequencies, we identified specific grid areas with unexpectedly high or low crash frequencies. These findings highlight the crucial role of near-miss data in urban traffic safety policy and planning, particularly relevant with the imminent rise of autonomous and connected vehicles. By integrating near-miss data into safety estimations, we can develop a more comprehensive understanding of traffic safety and, thus, more effectively address urban traffic risks. Full article

(This article belongs to the Special Issue Vehicle Safety and Crash Avoidance)

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20 pages, 4002 KiB

Open AccessArticle

A Novel Method of Time-Varying Formation Control Based on a Directed Graph for Multiple Autonomous Underwater Vehicles

by Gang Shao, Lei Wan and Huixi Xu

Appl. Sci. 2024, 14(14), 6377; https://doi.org/10.3390/app14146377 - 22 Jul 2024

Viewed by 1194

Abstract

Currently, autonomous underwater vehicles (AUVs) are facing various challenges, rendering multiple-AUV (multi-AUV) formation control a pivotal research direction. The issues surrounding formation control for a multi-AUV system to establish time-varying formations must be investigated. This paper discusses the formation protocol of multi-AUV systems [...] Read more.

Currently, autonomous underwater vehicles (AUVs) are facing various challenges, rendering multiple-AUV (multi-AUV) formation control a pivotal research direction. The issues surrounding formation control for a multi-AUV system to establish time-varying formations must be investigated. This paper discusses the formation protocol of multi-AUV systems in order to establish the defined time-varying formations. First, when these systems establish formations, the speed of each AUV can be equivalent. After that, consensus-based methods are used to solve the time-varying formation-control problem. The necessary and sufficient process of multi-AUV in achieving time-varying formations is proved. Furthermore, the formula for the time-varying formation center function is provided. Further, we present a protocol law for multi-AUVs to establish time-varying formations. Finally, the theoretical results of a simulation are presented, which validate the formation protocol. Full article

(This article belongs to the Special Issue Modeling, Guidance and Control of Marine Robotics)

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Figure 1
The autonomous underwater vehicle (AUV) coordinate diagram. Full article ">Figure 2
Two-loop formation-control scheme for multiple-AUV (multi-AUV) systems. Full article ">Figure 3
All AUVs operate at the same height (distance from the ocean floor). Full article ">Figure 4
AUV formation on the X–Y plane with N = 5. Full article ">Figure 5
Directed interaction topology G about the five AUVs. Full article ">Figure 6
The trajectories of five AUVs and <math display="inline"><semantics> <mrow> <mi>c</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math> in the simulation. (a) The position trajectories of five AUVs in the simulation; (b) the velocity trajectories of five AUVs in the simulation. Full article ">Figure 7
Position snapshots of <math display="inline"><semantics> <mrow> <mi>θ</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>c</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>c</mi> <mfenced> <mi>t</mi> </mfenced> <mi>t</mi> <mo>∈</mo> <mfenced close="]" open="["> <mrow> <mn>16</mn> <mi mathvariant="normal">s</mi> <mo>,</mo> <mn>21</mn> <mi mathvariant="normal">s</mi> </mrow> </mfenced> </mrow> </semantics></math> in the simulation. Full article ">Figure 8
State trajectories of five AUVs in the simulation and <math display="inline"><semantics> <mrow> <mi>c</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math>. (a) The position trajectories of five AUVs in the simulation; (b) the velocity trajectories of five AUVs in the simulation. Full article ">Figure 9
State trajectories of the five AUVs in the simulation and <math display="inline"><semantics> <mrow> <mi>c</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math>. (a) The position trajectories of the five AUVs in the simulation; (b) the velocity trajectories of the five AUVs in the simulation. Full article ">Figure 9 Cont.
State trajectories of the five AUVs in the simulation and <math display="inline"><semantics> <mrow> <mi>c</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math>. (a) The position trajectories of the five AUVs in the simulation; (b) the velocity trajectories of the five AUVs in the simulation. Full article ">

20 pages, 22124 KiB

Open AccessArticle

A Reversible Data-Hiding Method for Encrypted Images Based on Adaptive Quadtree Partitioning and MSB Prediction

by Ya Yue, Minqing Zhang, Fuqiang Di and Peizheng Lai

Appl. Sci. 2024, 14(14), 6376; https://doi.org/10.3390/app14146376 - 22 Jul 2024

Viewed by 885

Abstract

To address the vulnerability of the widely used block permutation and co-XOR (BPCX) encryption algorithm in reversible data-hiding in the encrypted domain (RDH-ED), which is susceptible to known-plaintext attacks (KPAs), and to enhance embedding capacity, we propose a novel technique of reversible data-hiding [...] Read more.

To address the vulnerability of the widely used block permutation and co-XOR (BPCX) encryption algorithm in reversible data-hiding in the encrypted domain (RDH-ED), which is susceptible to known-plaintext attacks (KPAs), and to enhance embedding capacity, we propose a novel technique of reversible data-hiding in encrypted images (RDH-EI). This method incorporates adaptive quadtree partitioning and most significant bit (MSB) prediction. To counteract KPAs, we introduce pixel modulation specifically targeting pixels within blocks of the same level during the encryption phase. During data embedding, we utilize tagging bits to indicate the state of the pixel blocks, capitalizing on pixel redundancy within those blocks to augment embedding capacity. Our experimental results demonstrate that our method not only achieves reversibility and separability but also significantly boosts embedding capacity and method security. Notably, the average embedding rate across the 10,000 images tested stands at 2.4731, surpassing previous methods by 0.2106 and 0.037, respectively. Full article

(This article belongs to the Section Computing and Artificial Intelligence)

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13 pages, 3138 KiB

Open AccessArticle

Iteratively Refined Multi-Channel Speech Separation

by Xu Zhang, Changchun Bao, Xue Yang and Jing Zhou

Appl. Sci. 2024, 14(14), 6375; https://doi.org/10.3390/app14146375 - 22 Jul 2024

Viewed by 864

Abstract

The combination of neural networks and beamforming has proven very effective in multi-channel speech separation, but its performance faces a challenge in complex environments. In this paper, an iteratively refined multi-channel speech separation method is proposed to meet this challenge. The proposed method [...] Read more.

The combination of neural networks and beamforming has proven very effective in multi-channel speech separation, but its performance faces a challenge in complex environments. In this paper, an iteratively refined multi-channel speech separation method is proposed to meet this challenge. The proposed method is composed of initial separation and iterative separation. In the initial separation, a time–frequency domain dual-path recurrent neural network (TFDPRNN), minimum variance distortionless response (MVDR) beamformer, and post-separation are cascaded to obtain the first additional input in the iterative separation process. In iterative separation, the MVDR beamformer and post-separation are iteratively used, where the output of the MVDR beamformer is used as an additional input to the post-separation network and the final output comes from the post-separation module. This iteration of the beamformer and post-separation is fully employed for promoting their optimization, which ultimately improves the overall performance. Experiments on the spatialized version of the WSJ0-2mix corpus showed that our proposed method achieved a signal-to-distortion ratio (SDR) improvement of 24.17 dB, which was significantly better than the current popular methods. In addition, the method also achieved an SDR of 20.2 dB on joint separation and dereverberation tasks. These results indicate our method’s effectiveness and significance in the multi-channel speech separation field. Full article

(This article belongs to the Special Issue Advanced Technology in Speech and Acoustic Signal Processing)

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21 pages, 15472 KiB

Open AccessArticle

Research on Bifurcated Origami Hydraulic Dampers for Real Road Vibration Loads

by Jingchao Guan, Baoluo Zheng, Yalan Li, Wei Zhao and Xilu Zhao

Appl. Sci. 2024, 14(14), 6374; https://doi.org/10.3390/app14146374 - 22 Jul 2024

Viewed by 888

Abstract

Cylindrical hydraulic dampers are commonly utilized to mitigate vibrations in machinery and structural applications. These devices generally feature a single linear stroke and are often linked to rotary joints to handle complex loading conditions. However, their installation in confined spaces, such as vehicle [...] Read more.

Cylindrical hydraulic dampers are commonly utilized to mitigate vibrations in machinery and structural applications. These devices generally feature a single linear stroke and are often linked to rotary joints to handle complex loading conditions. However, their installation in confined spaces, such as vehicle suspensions, poses considerable difficulties. In this research, we introduce an innovative bifurcated origami hydraulic damper with nonlinear damping capabilities. Initially, we formulated the collapsible conditional equations essential for the design of the bifurcated origami hydraulic dampers. We then examined the fluid dynamics within the damper and its flow channels, determining that the damping force is proportional to the square of the velocity. Furthermore, we developed motion equations based on the derived damping force and suggested vibration analysis methods using the Runge–Kutta approach. For the mass-spring vibration system, we created an experimental setup with the bifurcated origami hydraulic damper and performed vibration tests using noise signals recorded from a vehicle traveling on a gravel road, thus validating its damping performance and efficacy. Additional tests, which varied the orifice size at the end of the origami structure, as well as the type and temperature of the internal fluid, showed that the orifice size had a more pronounced effect on damping efficiency than the fluid type and temperature. This confirmed the vibration-damping effectiveness of the bifurcated origami hydraulic damper. Full article

(This article belongs to the Special Issue Vibration Problems in Engineering Science)

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19 pages, 5105 KiB

Open AccessArticle

Peak and Residual Shear Interface Measurement between Sand and Continuum Surfaces Using Ring Shear Apparatus

by Rayed Almasoudi, Firas Daghistani and Hossam Abuel-Naga

Appl. Sci. 2024, 14(14), 6373; https://doi.org/10.3390/app14146373 - 22 Jul 2024

Viewed by 910

Abstract

This study uses a ring shear apparatus to measure the interface shear stress between five types of sand and three surfaces: steel, PVC, and stone. Experiments were conducted under normal stresses of 25, 50, and 100 kPa at a constant shear rate of [...] Read more.

This study uses a ring shear apparatus to measure the interface shear stress between five types of sand and three surfaces: steel, PVC, and stone. Experiments were conducted under normal stresses of 25, 50, and 100 kPa at a constant shear rate of 0.5 mm/min. The research examines the impact of various sand properties, including particle size distribution, median particle size, particle shape, and initial density, as well as the surface roughness and hardness of continuum materials. The results show that interface shear strength is significantly influenced by the mechanical interlock between sand particles and surface asperities, which is affected by the normalized roughness and hardness of the materials. Machine learning models, including Multiple Linear Regression and Random Forest Regression, were used to predict peak and residual shear strengths, demonstrating high accuracy. Additionally, an empirical equation was generated using eight input parameters, considering the peak and residual interface shear strength as outputs. Full article

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19 pages, 9190 KiB

Open AccessReview

Effect of the Inter-Ring Delay Time on Rock Fragmentation: Field Tests at the Underground Mine

by Hui Chen, Chengyu Liu, Yin Feng and Haojie Yin

Appl. Sci. 2024, 14(14), 6372; https://doi.org/10.3390/app14146372 - 22 Jul 2024

Viewed by 1071

Abstract

The effect of inter-ring delay time (IRDT) on rock fragmentation in the tunnel excavation blasting was studied at the Xinjiang Beizhan Iron Mine, China, to improve the rock fragmentation and optimize the blast design. Blasting tests were conducted with an IRDT of 50, [...] Read more.

The effect of inter-ring delay time (IRDT) on rock fragmentation in the tunnel excavation blasting was studied at the Xinjiang Beizhan Iron Mine, China, to improve the rock fragmentation and optimize the blast design. Blasting tests were conducted with an IRDT of 50, 100, 150, 200, and 500 ms; each adjacent ring had an equal IRDT, and two replicate tests were conducted. The blasting plan with IRDT of 100 ms was the original blasting plan used in the mine. Two optimized blasting plans were proposed and implemented based on the experimental results, along with a control experiment using the original blasting plan. The fragment size of each blast test was measured and analyzed by the block-analyzed software. Both collision theoretical and field tests indicated that the IRDT plays an important role in rock fragmentation and that as the IRDT increases, the degree of rock fragmentation increases first and then decreases. For example, the fragment sizes X20, X50, and X80 showed an increase followed by a decrease; the percentage of large fragments (1-P750) showed a decline followed by a rise; the percentage of small fragments P25 showed an increase followed by a decline. The blasting plan with an IRDT of 150 ms had the most optimal rock fragmentation effect, with the lowest percentage of large fragments, the highest percentage of small fragments, and the smallest average fragment size of X50. Furthermore, the two optimized blasting plans demonstrated better control over blasting costs and rock fragmentation compared to the original blasting plan. Full article

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26 pages, 17181 KiB

Open AccessArticle

The Collection and Compilation of Small Group Data for Scenario Setting of Simulations and Experiments

by Yi Xu and Ying Zhou

Appl. Sci. 2024, 14(14), 6371; https://doi.org/10.3390/app14146371 - 22 Jul 2024

Viewed by 793

Abstract

The influence of small groups in evacuation cannot be ignored. However, the current simulations and experimental studies have oversimplified the settings of small groups and evacuation scenarios. A significant disparity exists between the findings of existing studies and real-world scenarios. This paper compiled [...] Read more.

The influence of small groups in evacuation cannot be ignored. However, the current simulations and experimental studies have oversimplified the settings of small groups and evacuation scenarios. A significant disparity exists between the findings of existing studies and real-world scenarios. This paper compiled data on the number and size of small groups and the location of small group members in built environments. Subsequently, a scenario with intricate functions and shapes was established, and finally, these data was employed in agent-based simulations. The data encompassed 50 small groups comprising a total of 111 members. These groups, ranging from 2 to 4 members each, exhibited spatial separations between members spanning from 1 m to 23 m. Simulation outcomes indicated a detrimental effect of small groups on overall evacuation. A significant and positive correlation was observed between the distance separating small group members and the escalation in evacuation time, total jam time, and evacuation distance. The data provides a foundation for configuring initial scenarios in small group evacuation experiments and simulations. The simulation results can provide a basis for hospital safety evacuation management. Full article

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15 pages, 6965 KiB

Open AccessArticle

A New Reversible Data Hiding Method Using a Proportional Relation between Peak Signal-to-Noise Ratio and Embedding Capacity on Convolutional Neural Network

by Yong-Yeol Bae, Dae-Jea Cho and Ki-Hyun Jung

Appl. Sci. 2024, 14(14), 6370; https://doi.org/10.3390/app14146370 - 22 Jul 2024

Viewed by 855

Abstract

In the rapidly evolving fields of artificial intelligence and various industries, the secure processing and management of massive data have become paramount. This paper introduces an innovative reversible data hiding (RDH) method that leverages a Convolutional Neural Network (CNN)-based predictor to generate a [...] Read more.

In the rapidly evolving fields of artificial intelligence and various industries, the secure processing and management of massive data have become paramount. This paper introduces an innovative reversible data hiding (RDH) method that leverages a Convolutional Neural Network (CNN)-based predictor to generate a predicted image from a given cover image. The secret data are ingeniously embedded within the differences in pixel values between the cover and predicted images. Our experimental analysis reveals a notable reduction in image distortion with increasing secret data size, showcasing the method’s potential for diverse applications. The unique aspect of our approach lies in the proportional relation between the Peak Signal-to-Noise Ratio (PSNR) and Embedding Capacity, highlighting its efficacy and efficiency in reversible data hiding. Full article

(This article belongs to the Section Computing and Artificial Intelligence)

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23 pages, 9408 KiB

Open AccessArticle

Evolution of Industrial Robots from the Perspective of the Metaverse: Integration of Virtual and Physical Realities and Human–Robot Collaboration

by Jing You, Zhiyuan Wu, Wei Wei, Ning Li and Yuhua Yang

Appl. Sci. 2024, 14(14), 6369; https://doi.org/10.3390/app14146369 - 22 Jul 2024

Cited by 1 | Viewed by 1971

Abstract

During the transition from Industry 4.0 to Industry 5.0, industrial robotics technology faces the need for intelligent and highly integrated development. Metaverse technology creates immersive and interactive virtual environments, allowing technicians to perform simulations and experiments in the virtual world, and overcoming the [...] Read more.

During the transition from Industry 4.0 to Industry 5.0, industrial robotics technology faces the need for intelligent and highly integrated development. Metaverse technology creates immersive and interactive virtual environments, allowing technicians to perform simulations and experiments in the virtual world, and overcoming the limitations of traditional industrial operations. This paper explores the application and evolution of metaverse technology in the field of industrial robotics, focusing on the realization of virtual–real integration and human–machine collaboration. It proposes a design framework for a virtual–real interaction system based on the ROS and WEB technologies, supporting robot connectivity, posture display, coordinate axis conversion, and cross-platform multi-robot loading. This paper emphasizes the study of two key technologies for the system: virtual–real model communication and virtual–real model transformation. A general communication mechanism is designed and implemented based on the ROS, using the ROS topic subscription to achieve connection and real-time data communication between physical robots and virtual models, and utilizing URDF model transformation technology for model invocation and display. Compared with traditional simulation software, i.e., KUKA Sim PRO (version 1.1) and RobotStudio (version 6.08), the system improves model loading by 45.58% and 24.72%, and the drive response by 41.50% and 28.75%. This system not only supports virtual simulation and training but also enables the operation of physical industrial robots, provides persistent data storage, and supports action reproduction and offline data analysis and decision making. Full article

(This article belongs to the Topic Smart Production in Terms of Industry 4.0 and 5.0)

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19 pages, 1263 KiB

Open AccessArticle

Robust Estimation Method against Poisoning Attacks for Key-Value Data with Local Differential Privacy

by Hikaru Horigome, Hiroaki Kikuchi, Masahiro Fujita and Chia-Mu Yu

Appl. Sci. 2024, 14(14), 6368; https://doi.org/10.3390/app14146368 - 22 Jul 2024

Cited by 1 | Viewed by 1000

Abstract

Local differential privacy (LDP) protects user information from potential threats by randomizing data on individual devices before transmission to untrusted collectors. This method enables collectors to derive user statistics by analyzing randomized data, thereby presenting a promising avenue for privacy-preserving data collection. In [...] Read more.

Local differential privacy (LDP) protects user information from potential threats by randomizing data on individual devices before transmission to untrusted collectors. This method enables collectors to derive user statistics by analyzing randomized data, thereby presenting a promising avenue for privacy-preserving data collection. In the context of key–value data, in which discrete and continuous values coexist, PrivKV has been introduced as an LDP protocol to ensure secure collection. However, this framework is susceptible to poisoning attacks. To address this vulnerability, we propose an expectation maximization (EM)-based algorithm combined with a cryptographic protocol to facilitate secure random sampling. Our LDP protocol, known as emPrivKV, exhibits two key advantages: it improves the accuracy of statistical information estimation from randomized data, and enhances resilience against the manipulation of statistics, that is, poisoning attacks. These attacks involve malicious users manipulating the analysis results without detection. This study presents the empirical results of applying the emPrivKV protocol to both synthetic and open datasets, highlighting a notable improvement in the precision of statistical value estimation and robustness against poisoning attacks. As a result, emPrivKV improved the frequency and the mean gains by

17.1 %

and

25.9 %

, respectively, compared to PrivKV, with the number of fake users being

0.1

of the genuine users. Our findings contribute to the ongoing discourse on refining LDP protocols for key–value data in scenarios involving privacy-sensitive information. Full article

(This article belongs to the Special Issue Progress and Research in Cybersecurity and Data Privacy)

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13 pages, 3542 KiB

Open AccessArticle

Study on the Anti-Interference Performance of Substrate-Free PEDOT:PSS ECG Electrodes

by Chunlin Li, Ke Xu and Yuanfen Chen

Appl. Sci. 2024, 14(14), 6367; https://doi.org/10.3390/app14146367 - 22 Jul 2024

Viewed by 1040

Abstract

Substrate-free electrodes are promising dry electrodes for long-term physiological electrical signal monitoring due to their ultra-thinness, conformal contact, and stable skin–electrode impedance. However, the response of substrate-free electrodes to various disturbances during electrocardiogram (ECG) monitoring and the corresponding optimization needs to be investigated. [...] Read more.

Substrate-free electrodes are promising dry electrodes for long-term physiological electrical signal monitoring due to their ultra-thinness, conformal contact, and stable skin–electrode impedance. However, the response of substrate-free electrodes to various disturbances during electrocardiogram (ECG) monitoring and the corresponding optimization needs to be investigated. This paper investigates the specific effects of various influencing factors on skin–electrode impedance and ECG during electrocardiogram (ECG) detection. The research utilizes substrate-free poly(3,4-ethylenedioxythiophene)/poly(styrene-sulfonate) (PEDOT:PSS) electrodes. The investigation employs several methods, including skin–electrode impedance comparison, ECG waveform analysis, spectrum analysis, and signal-to-noise ratio (SNR) evaluation. To avoid the impact of physiological state differences in subjects at different times, relevant data were only compared with the same group of experiments conducted in the same period. The results demonstrate that the substrate-free conformal contact PEDOT:PSS electrode has more stable skin–electrode impedance and could obtain a more stable ECG than partial contact electrodes (the SNR of the partial contact and conformal contact electrodes are 1.2768 ± 4.0299 dB and 7.2637 ± 1.4897 dB, respectively). Furthermore, the ECG signal quality of the substrate-free conformal contact PEDOT:PSS electrode was independent of the electrode area and shape (the SNRs of the large, medium, and small electrodes are 4.0447 ± 0.4616 dB, 3.9115 ± 0.5885 dB, and 4.1556 ± 0.5557 dB, respectively; the SNRs of the circular, square, and triangular electrodes are 9.2649 ± 0.6326 dB, 9.2471 ± 0.6806 dB, and 9.1514 ± 0.6875 dB, respectively), showing high signal acquisition capability that is the same as microneedle electrodes and better than fabric electrodes. The results of clothing friction effects show that skin–electrode impedance stability was important for ECG stability, while the impedance value was not (the SNRs of friction and non-friction electrodes are 2.4128 ± 7.0784 dB and 9.2164 ± 0.6696 dB, respectively). Moreover, the skin–electrode impedance maintains stability even at a high breathing frequency, but the ECG signal fluctuates at a high breathing frequency. This experiment demonstrates that even when the skin–electrode impedance remains stable, the ECG signal can still be susceptible to interference from other factors. This study suggests that substrate-free PEDOT:PSS that could form conformal contact with the skin has higher skin–electrode impedance stability and could measure a high ECG signal even with a small electrode area, demonstrating its potential as dry ECG electrodes, but the interference from other physiological electrical signals may require better circuit design. Full article

(This article belongs to the Section Biomedical Engineering)

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(a) Ag/AgCl electrode; (b) PEDOT:PSS electrode. Full article ">Figure 2
(a) PEDOT:PSS dry electrode was attached to the skin surface, dominated by van der Waals force; (b) PEDOT:PSS was wetted and gelled on skin; (c) Conformal contact of PEDOT:PSS with skin, dominated by intermolecular hydrogen bonds. Full article ">Figure 3
(a) Skin–electrode impedance measurement; (b) Schematic of ECG detection. Full article ">Figure 4
Schematic diagram of an equivalent circuit model for the skin–electrode impedance. Full article ">Figure 5
Results of different contact states (a) Bode plot of skin–electrode impedance; (b) Spectrogram of different contact states; (c) ECG of different contact states. Full article ">Figure 6
Results for different electrode sizes (a) Bode plot of skin–electrode impedance; (b) Spectrogram of different electrode sizes; (c) ECG waveforms. Full article ">Figure 7
Results of different electrode shapes with the same area (a) Bode plot of skin–electrode impedance; (b) Spectrogram of ECG; (c) ECG waveforms of different shapes. Full article ">Figure 8
(a) Skin–electrode impedance modulus at 1 Hz frequency; (b) Impedance modulus at 10 Hz frequency; (c) Impedance modulus at 30 Hz frequency; (d) Spectrogram of different electrode states; (e) ECG waveforms of different electrode states. Full article ">Figure 9
Experimental results for different breathing frequencies. (a) Bode plot of skin–electrode impedance; (b) Spectrogram of ECG; (c) Waveform of ECG. Full article ">

19 pages, 3852 KiB

Open AccessArticle

Transforming Interactive Educational Content into Immersive Virtual Reality Learning Objects

by Pranas Jaruševičius, Lukas Paulauskas, Vaidotas Drungilas, Mantas Jurgelaitis and Tomas Blažauskas

Appl. Sci. 2024, 14(14), 6366; https://doi.org/10.3390/app14146366 - 22 Jul 2024

Cited by 3 | Viewed by 1361

Abstract

Currently, the integration of immersive virtual reality applications into learning management systems is limited, which disadvantages kinesthetic learners, as the majority of learning material is mostly written or visual in nature. This research presents a method on how to transform existing conventional learning [...] Read more.

Currently, the integration of immersive virtual reality applications into learning management systems is limited, which disadvantages kinesthetic learners, as the majority of learning material is mostly written or visual in nature. This research presents a method on how to transform existing conventional learning material into immersive virtual reality and integrate it into learning management systems, demonstrating it with a pilot study and an immersive virtual reality application prototype. The prototype application uses WebXR technology and provides integration into the Moodle learning management system using the Sharable Content Object Reference Model standard. The developed learning object was evaluated using the System Usability Scale, Web-based Learning Tool evaluation scale and the igroup Presence Questionnaire. The results of the pilot study revealed that the learning object performed above average in all tested fields and is preferable to established non-IVR solutions. Full article

(This article belongs to the Special Issue Virtual Reality Based Serious Games: Developments and Applications)

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The concepts of the proposed IVR application integration to the learning management systems method. Full article ">Figure 2
Transformation process that adapts existing study courses to include IVR LOs. Full article ">Figure 3
Screenshots from within the IVR application, showcasing various views and objects throughout the prototype, such as the main menu, the main task, and additional learning material. Full article ">Figure 4
Architecture for IVR application and its integration into Moodle LMS. Full article ">Figure 5
Sample Moodle LMS report of the participants’ results in the IVR application. Full article ">Figure 6
Certified desktop 2D interactive LO from “Emokykla.lt” on the topic of the human skeleton. Full article ">Figure 7
IVR application and 2D interactive LO WBLT scale scores comparison in the domains of learning, design, and engagement. Full article ">Figure 8
Graph showing how the percentile ranks associate with SUS scores. The letter notation in the diagram correspond to a grade of the system based on the scores, A meaning excellent, B—good, C and D—okay, and F—poor. Full article ">

26 pages, 3410 KiB

Open AccessReview

Strategic Insights into Integrated Photonics: Core Concepts, Practical Deployments, and Future Outlook

by Muhammad A. Butt and Xavier Mateos

Appl. Sci. 2024, 14(14), 6365; https://doi.org/10.3390/app14146365 - 22 Jul 2024

Cited by 1 | Viewed by 4057

Abstract

Integrated photonics is a cutting-edge field that merges optics and electronics on a single microchip, revolutionizing how we manipulate and transmit light. Imagine traditional bulky optical systems condensed onto a chip smaller than a fingernail, enabling faster communication, more efficient sensors, and advanced [...] Read more.

Integrated photonics is a cutting-edge field that merges optics and electronics on a single microchip, revolutionizing how we manipulate and transmit light. Imagine traditional bulky optical systems condensed onto a chip smaller than a fingernail, enabling faster communication, more efficient sensors, and advanced computing. At its core, integrated photonics relies on guiding light through waveguides etched onto semiconductor substrates, analogous to how wires conduct electricity in traditional electric circuits. These waveguides can route, modulate, and detect light signals with unprecedented precision and speed. This technology holds immense promise across various domains. Despite its immense potential, integrated photonics faces challenges, including manufacturing complexities and integration with existing electronic systems. However, ongoing research and advancements continue to push the boundaries, promising a future where light-based technologies seamlessly integrate into our everyday lives, powering a new era of innovation and connectivity. Full article

(This article belongs to the Special Issue Feature Review Papers in Optics and Lasers)

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16 pages, 3790 KiB

Open AccessArticle

Mechanical Behavior of Low-Strength Hydraulic Lime Concrete Reinforced with Flexible Fibers under Quasi-Static and Dynamic Conditions

by Ángel De La Rosa, Lucía Garijo, Vaibhav W. Masih and Gonzalo Ruiz

Appl. Sci. 2024, 14(14), 6364; https://doi.org/10.3390/app14146364 - 22 Jul 2024

Viewed by 911

Abstract

We investigate the effect of flexible fiber reinforcement on low-strength hydraulic lime concrete. This type of concrete is occasionally necessary to ensure compatibility with the substrate, particularly in the conservation and rehabilitation of historical heritage. For this purpose, we designed a matrix of [...] Read more.

We investigate the effect of flexible fiber reinforcement on low-strength hydraulic lime concrete. This type of concrete is occasionally necessary to ensure compatibility with the substrate, particularly in the conservation and rehabilitation of historical heritage. For this purpose, we designed a matrix of hydraulic lime concrete based on a mix design method we proposed previously and added different amounts of polyvinyl alcohol fiber (volumetric contents of 0.3%, 0.6%, 0.9%, and 1.2%). We then conducted three-point bending tests on prismatic specimens with a central notch under quasi-static (displacement rate of 4 ×

10^{- 4}

mm/s) and dynamic (4 mm/s) conditions, using a servo-hydraulic machine. The results indicate that, in both quasi-static and dynamic regimes, the flexural strength, the residual flexural strengths for different crack openings, and the work of fracture increase as the fiber content increases. Furthermore, transitioning from one regime to another (by increasing the strain rate or velocity) leads to a significant increase in these mechanical parameters. Full article

(This article belongs to the Special Issue Advanced Technologies in Cultural Heritage)

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28 pages, 3615 KiB

Open AccessReview

Shipbuilding 4.0: A Systematic Literature Review

by Xiaowei Zhang and Daoyi Chen

Appl. Sci. 2024, 14(14), 6363; https://doi.org/10.3390/app14146363 - 22 Jul 2024

Cited by 1 | Viewed by 3048

Abstract

Existing research in the shipbuilding field tends to focus on isolated single aspects of Industry 4.0 (I4.0) without a full picture. To address this gap, this paper seeks to offer a thorough and in-depth examination of the concepts and technologies necessary to integrate [...] Read more.

Existing research in the shipbuilding field tends to focus on isolated single aspects of Industry 4.0 (I4.0) without a full picture. To address this gap, this paper seeks to offer a thorough and in-depth examination of the concepts and technologies necessary to integrate I4.0 into the design, construction, maintenance, and other stages throughout the entire life cycle of a ship. This paper will firstly examine the recent developments and identify the gaps in I4.0 application within shipbuilding. By conducting a systematic literature review on 68 publications through an appropriate review methodology, we synthesize the current state of I4.0 research in the shipbuilding industry, propose a framework for the application of I4.0 in shipbuilding to analyze the progression and research agenda of I4.0 in the shipbuilding sector, and discuss its implications. The Shipbuilding 4.0 framework proposed comprises five main components: concepts, value chain, smart factory, smart manufacturing, infrastructure, and technologies. The proposed framework aims to enhance the understanding of both academics and practitioners regarding the specific needs of the shipbuilding industry and the role I4.0 can and should play in its advancement. Full article

(This article belongs to the Special Issue Smart Factory, Industry 4.0 and Sustainability)

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14 pages, 5500 KiB

Open AccessArticle

Laboratory Evaluation of Wear Particle Emissions and Suspended Dust in Tire–Asphalt Concrete Pavement Friction

by Jongsub Lee, Ohsun Kwon, Yujoong Hwang and Gyumin Yeon

Appl. Sci. 2024, 14(14), 6362; https://doi.org/10.3390/app14146362 - 22 Jul 2024

Cited by 1 | Viewed by 1011

Abstract

This study aims to evaluate the tire–road-wear particles (TRWPs) and suspended dust generated based on the nominal maximum aggregate size (NMAS) of the polymer-modified stone mastic asphalt (SMA) mixtures indoors. The SMA mixtures containing styrene butadiene styrene (SBS) polymer and the NMASs of [...] Read more.

This study aims to evaluate the tire–road-wear particles (TRWPs) and suspended dust generated based on the nominal maximum aggregate size (NMAS) of the polymer-modified stone mastic asphalt (SMA) mixtures indoors. The SMA mixtures containing styrene butadiene styrene (SBS) polymer and the NMASs of 19, 13, 10, 8, and 6 mm were used. Dust was generated from the wear of the tires and the pavement inside the indoor chamber by using the laboratory tire–road-wear particle generation and evaluation tester (LTRWP tester) developed by Korea Expressway Corporation (KEC). In this method, a cylindrical asphalt-mixture specimen rotates in the center, and a load is applied using three tires on the sides of the test specimen. During the test, a digital sensor was used to measure the concentration for each particle size. After the test was completed, the dust was collected and weighed. According to the test results, the generated TRWP emissions were reduced by approximately 0.15 g as the NMAS of the SMA mixture decreased by 1 mm. TRWP emissions decreased by 20% when using the 6 mm SMA mixture compared to the 13 mm SMA mixture. For practical application, a predicted equation of TRWP emissions estimation was developed by using the concentration of suspended dust measured by the digital sensor in the LTRWP tester. LTRWP can be used as an indoor test method to evaluate pavement and tire materials to reduce the amount of dust generated from tire and pavement wear. Full article

(This article belongs to the Special Issue Advances in Renewable Asphalt Pavement Materials)

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20 pages, 2140 KiB

Open AccessArticle

Providing Security for Flash Loan System Using Cryptocurrency Wallets Supported by XSalsa20 in a Blockchain Environment

by Mishall Al-Zubaidie and Wid Alaa Jebbar

Appl. Sci. 2024, 14(14), 6361; https://doi.org/10.3390/app14146361 - 22 Jul 2024

Cited by 2 | Viewed by 2087

Abstract

The days of long lines at banks and piles of paperwork are long gone. The lending landscape has been completely transformed by digital loans, which provide a quick, easy, and frequently paperless transactions. A payee can apply for a digital loan anytime, anywhere. [...] Read more.

The days of long lines at banks and piles of paperwork are long gone. The lending landscape has been completely transformed by digital loans, which provide a quick, easy, and frequently paperless transactions. A payee can apply for a digital loan anytime, anywhere. The entire lending procedure is accessible and efficient, but the availability of data on the Internet provides many risks and threats, where there are certain difficulties in the world of digital lending and data security, and privacy are major concerns. It is important to address the possibility of predatory lending practices that target weaker payees, especially with flash loans, which are considered a critical type of digital loan, as they add additional pressure to banks in terms of security because they return to the same block of the blockchain, and the possibility of tampering with them is considered great. Therefore, we have developed a security protocol based on the principle of digital cryptocurrency wallets: these digital wallets are protected by our use of the Xsalsa20 algorithm. It has high specifications and is enhanced with the usage of the Crow search algorithm, which guarantees fast and efficient search results. After the analysis of the proposed system in the Tamarin Prover tool, we obtained proof of a lot of security properties like data authenticity, perfect forward secrecy, and many others, which constitute the matter that gives our system the power of security. Also, we obtained 0.6667 ms. as the rate of processing speed, 2990 ms. as the time required by the proposed system to repay loans after the conditions are met, and, finally, our proposed system has the power to present a flexible property by creating 29,700 loans every 3 s; by this, we obtained a system that is secure, authentic, fast, and flexible. Full article

(This article belongs to the Special Issue Advanced Cybersecurity Applications: Solutions to Counteract Cyber Threats)

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18 pages, 10474 KiB

Open AccessArticle

Adaptive Frame Sampling and Feature Alignment for Multi-Frame Infrared Small Target Detection

by Chuanhong Yao and Haitao Zhao

Appl. Sci. 2024, 14(14), 6360; https://doi.org/10.3390/app14146360 - 22 Jul 2024

Viewed by 1196

Abstract

In recent years, infrared images have attracted widespread attention, due to their extensive application in low-visibility search and rescue, forest fire monitoring, ground target monitoring, and other fields. Infrared small target detection technology plays a vital role in these applications. Although there has [...] Read more.

In recent years, infrared images have attracted widespread attention, due to their extensive application in low-visibility search and rescue, forest fire monitoring, ground target monitoring, and other fields. Infrared small target detection technology plays a vital role in these applications. Although there has been significant research over the years, accurately detecting infrared small targets in complex backgrounds remains a significant challenge. Multi-frame detection methods can significantly improve detection performance in these cases. However, current multi-frame methods face difficulties in balancing the number of input frames and detection speed, and cannot effectively handle the background motion caused by movement of the infrared camera. To address these issues, we propose an adaptive frame sampling method and a detection network aligned at the feature level. Our adaptive frame sampling method uses mutual information to measure motion changes between adjacent frames, construct a motion distribution, and sample frames with uniform motion based on the averaged motion distribution. Our detection network handles background motion by predicting a homography flow matrix that aligns features at the feature level. Extensive evaluation of all components showed that the proposed method can more effectively perform multi-frame infrared small target detection. Full article

(This article belongs to the Special Issue Deep Learning and Machine Learning in Image Processing and Pattern Recognition)

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