The 2023 MDPI Annual Report has
been released!
 
12 pages, 1098 KiB  
Article
Torque Calculation and Dynamical Response in Halbach Array Coaxial Magnetic Gears through a Novel Analytical 2D Model
by Panteleimon Tzouganakis, Vasilios Gakos, Christos Kalligeros, Christos Papalexis, Antonios Tsolakis and Vasilios Spitas
Computation 2024, 12(5), 88; https://doi.org/10.3390/computation12050088 (registering DOI) - 27 Apr 2024
Abstract
Coaxial magnetic gears have piqued the interest of researchers due to their numerous benefits over mechanical gears. These include reduced noise and vibration, enhanced efficiency, lower maintenance costs, and improved backdrivability. However, their adoption in industry has been limited by drawbacks like lower [...] Read more.
Coaxial magnetic gears have piqued the interest of researchers due to their numerous benefits over mechanical gears. These include reduced noise and vibration, enhanced efficiency, lower maintenance costs, and improved backdrivability. However, their adoption in industry has been limited by drawbacks like lower torque density and slippage at high torque levels. This work presents an analytical 2D model to compute the magnetic potential in Halbach array coaxial magnetic gears for every rotational angle, geometry configuration, and magnet specifications. This model calculates the induced torques and torque ripple in both rotors using the Maxwell Stress Tensor. The results were confirmed through Finite Element Analysis (FEA). Unlike FEA, this analytical model directly produces harmonics values, leading to faster computational times as it avoids torque calculations at each time step. In a case study, a standard coaxial magnetic gear was compared to one with a Halbach array, revealing a 14.3% improvement in torque density and a minor reduction in harmonics that cause torque ripple. Additionally, a case study was conducted to examine slippage in both standard and Halbach array gears during transient operations. The Halbach array coaxial magnetic gear demonstrated a 13.5% lower transmission error than its standard counterpart. Full article
15 pages, 476 KiB  
Article
Differentiating Pressure Ulcer Risk Levels through Interpretable Classification Models Based on Readily Measurable Indicators
by Eugenio Vera-Salmerón, Carmen Domínguez-Nogueira, José A. Sáez, José L. Romero-Béjar and Emilio Mota-Romero
Healthcare 2024, 12(9), 913; https://doi.org/10.3390/healthcare12090913 (registering DOI) - 27 Apr 2024
Abstract
Pressure ulcers carry a significant risk in clinical practice. This paper proposes a practical and interpretable approach to estimate the risk levels of pressure ulcers using decision tree models. In order to address the common problem of imbalanced learning in nursing classification datasets, [...] Read more.
Pressure ulcers carry a significant risk in clinical practice. This paper proposes a practical and interpretable approach to estimate the risk levels of pressure ulcers using decision tree models. In order to address the common problem of imbalanced learning in nursing classification datasets, various oversampling configurations are analyzed to improve the data quality prior to modeling. The decision trees built are based on three easily identifiable and clinically relevant pressure ulcer risk indicators: mobility, activity, and skin moisture. Additionally, this research introduces a novel tabular visualization method to enhance the usability of the decision trees in clinical practice. Thus, the primary aim of this approach is to provide nursing professionals with valuable insights for assessing the potential risk levels of pressure ulcers, which could support their decision-making and allow, for example, the application of suitable preventive measures tailored to each patient’s requirements. The interpretability of the models proposed and their performance, evaluated through stratified cross-validation, make them a helpful tool for nursing care in estimating the pressure ulcer risk level. Full article
(This article belongs to the Section Artificial Intelligence in Medicine)
36 pages, 7366 KiB  
Article
An Audio-Based SLAM for Indoor Environments: A Robotic Mixed Reality Presentation
by Elfituri S. F. Lahemer and Ahmad Rad
Sensors 2024, 24(9), 2796; https://doi.org/10.3390/s24092796 (registering DOI) - 27 Apr 2024
Abstract
In this paper, we present a novel approach referred to as the audio-based virtual landmark-based HoloSLAM. This innovative method leverages a single sound source and microphone arrays to estimate the voice-printed speaker’s direction. The system allows an autonomous robot equipped with a single [...] Read more.
In this paper, we present a novel approach referred to as the audio-based virtual landmark-based HoloSLAM. This innovative method leverages a single sound source and microphone arrays to estimate the voice-printed speaker’s direction. The system allows an autonomous robot equipped with a single microphone array to navigate within indoor environments, interact with specific sound sources, and simultaneously determine its own location while mapping the environment. The proposed method does not require multiple audio sources in the environment nor sensor fusion to extract pertinent information and make accurate sound source estimations. Furthermore, the approach incorporates Robotic Mixed Reality using Microsoft HoloLens to superimpose landmarks, effectively mitigating the audio landmark-related issues of conventional audio-based landmark SLAM, particularly in situations where audio landmarks cannot be discerned, are limited in number, or are completely missing. The paper also evaluates an active speaker detection method, demonstrating its ability to achieve high accuracy in scenarios where audio data are the sole input. Real-time experiments validate the effectiveness of this method, emphasizing its precision and comprehensive mapping capabilities. The results of these experiments showcase the accuracy and efficiency of the proposed system, surpassing the constraints associated with traditional audio-based SLAM techniques, ultimately leading to a more detailed and precise mapping of the robot’s surroundings. Full article
(This article belongs to the Section Navigation and Positioning)
16 pages, 567 KiB  
Article
Biped Gait Stability Classification Based on the Predicted Step Viability
by Pedro Parik-Americano, Jorge Igual, Larissa Driemeier, Eric Cito Becman and Arturo Forner-Cordero
Biomimetics 2024, 9(5), 265; https://doi.org/10.3390/biomimetics9050265 (registering DOI) - 27 Apr 2024
Abstract
In this paper, we address the challenge of ensuring stability in bipedal walking robots and exoskeletons. We explore the feasibility of real-time implementation for the Predicted Step Viability algorithm (PSV), a complex multi-step optimization criterion for planning future steps in bipedal gait. To [...] Read more.
In this paper, we address the challenge of ensuring stability in bipedal walking robots and exoskeletons. We explore the feasibility of real-time implementation for the Predicted Step Viability algorithm (PSV), a complex multi-step optimization criterion for planning future steps in bipedal gait. To overcome the high computational cost of the PSV algorithm, we performed an analysis using 11 classification algorithms and a stacking strategy to predict if a step will be stable or not. We generated three datasets of increasing complexity through PSV simulations to evaluate the classification performance. Among the classifiers, k Nearest Neighbors, Support Vector Machine with Radial Basis Function Kernel, Decision Tree, and Random Forest exhibited superior performance. Multi-Layer Perceptron also consistently performed well, while linear-based algorithms showed lower performance. Importantly, the use of stacking did not significantly improve performance. Our results suggest that the feature vector applied with this approach is applicable across various robotic models and datasets, provided that training data is balanced and sufficient points are used. Notably, by leveraging classifiers, we achieved rapid computation of results in less than 1 ms, with minimal computational cost. Full article
(This article belongs to the Section Locomotion and Bioinspired Robotics)
20 pages, 17655 KiB  
Article
DiT-Gesture: A Speech-Only Approach to Stylized Gesture Generation
by Fan Zhang, Zhaohan Wang, Xin Lyu, Naye Ji, Siyuan Zhao and Fuxing Gao
Electronics 2024, 13(9), 1702; https://doi.org/10.3390/electronics13091702 (registering DOI) - 27 Apr 2024
Abstract
The generation of co-speech gestures for digital humans is an emerging area in the field of virtual human creation. Prior research has progressed by using acoustic and semantic information as input and adopting a classification method to identify the person’s ID and emotion [...] Read more.
The generation of co-speech gestures for digital humans is an emerging area in the field of virtual human creation. Prior research has progressed by using acoustic and semantic information as input and adopting a classification method to identify the person’s ID and emotion for driving co-speech gesture generation. However, this endeavor still faces significant challenges. These challenges go beyond the intricate interplay among co-speech gestures, speech acoustic, and semantics; they also encompass the complexities associated with personality, emotion, and other obscure but important factors. This paper introduces “DiT-Gestures”, a speech-conditional diffusion-based and non-autoregressive transformer-based generative model with the WavLM pre-trained model and a dynamic mask attention network (DMAN). It can produce individual and stylized full-body co-speech gestures by only using raw speech audio, eliminating the need for complex multimodal processing and manual annotation. Firstly, considering that speech audio contains acoustic and semantic features and conveys personality traits, emotions, and more subtle information related to accompanying gestures, we pioneer the adaptation of WavLM, a large-scale pre-trained model, to extract the style from raw audio information. Secondly, we replace the causal mask by introducing a learnable dynamic mask for better local modeling in the neighborhood of the target frames. Extensive subjective evaluation experiments are conducted on the Trinity, ZEGGS, and BEAT datasets to confirm WavLM’s and the model’s ability to synthesize natural co-speech gestures with various styles. Full article
16 pages, 6137 KiB  
Article
An End-to-End Artificial Intelligence of Things (AIoT) Solution for Protecting Pipeline Easements against External Interference—An Australian Use-Case
by Umair Iqbal, Johan Barthelemy and Guillaume Michal
Sensors 2024, 24(9), 2799; https://doi.org/10.3390/s24092799 (registering DOI) - 27 Apr 2024
Abstract
High-pressure pipelines are critical for transporting hazardous materials over long distances, but they face threats from third-party interference activities. Preventive measures are implemented, but interference accidents can still occur, making the need for high-quality detection strategies vital. This paper proposes an end-to-end Artificial [...] Read more.
High-pressure pipelines are critical for transporting hazardous materials over long distances, but they face threats from third-party interference activities. Preventive measures are implemented, but interference accidents can still occur, making the need for high-quality detection strategies vital. This paper proposes an end-to-end Artificial Intelligence of Things (AIoT) solution to detect potential interference threats in real time. The solution involves developing a smart visual sensor capable of processing images using state-of-the-art computer vision algorithms and transmitting alerts to pipeline operators in real time. The system’s core is based on the object-detection model (e.g., You Only Look Once version 4 (YOLOv4) and DETR with Improved deNoising anchOr boxes (DINO)), trained on a custom Pipeline Visual Threat Assessment (Pipe-VisTA) dataset. Among the trained models, DINO was able to achieve the best Mean Average Precision (mAP) of 71.2% for the unseen test dataset. However, for the deployment on a limited computational-ability edge computer (i.e., the NVIDIA Jetson Nano), the simpler and TensorRT-optimized YOLOv4 model was used, which achieved a mAP of 61.8% for the test dataset. The developed AIoT device captures the image using a camera, processes on the edge using the trained YOLOv4 model to detect the potential threat, transmits the threat alert to a Fleet Portal via LoRaWAN, and hosts the alert on a dashboard via a satellite network. The device has been fully tested in the field to ensure its functionality prior to deployment for the SEA Gas use-case. The AIoT smart solution has been deployed across the 10km stretch of the SEA Gas pipeline across the Murray Bridge section. In total, 48 AIoT devices and three Fleet Portals are installed to ensure the line-of-sight communication between the devices and portals. Full article
(This article belongs to the Section Sensing and Imaging)
26 pages, 4392 KiB  
Article
Methodology of Chip Temperature Measurement and Safety Machining Assessment in Dry Rough Milling of Magnesium Alloys Using Different Helix Angle Tools
by Ireneusz Zagórski, Piotr Zgórniak, Witold Habrat, José Machado and Stanisław Legutko
Materials 2024, 17(9), 2063; https://doi.org/10.3390/ma17092063 (registering DOI) - 27 Apr 2024
Abstract
This paper presents the methodology of measuring chip temperature in the cutting zone in the rough milling of magnesium alloys. Infrared measurements are taken to determine the effect of variable cutting speed, feed per tooth, and depth of cut on the maximum temperature [...] Read more.
This paper presents the methodology of measuring chip temperature in the cutting zone in the rough milling of magnesium alloys. Infrared measurements are taken to determine the effect of variable cutting speed, feed per tooth, and depth of cut on the maximum temperature of chips. Thermal images of chip temperature for a generated collective frame and corresponding histograms are presented. Chip temperatures are presented in numerical terms as median and average values; maximum and minimum values; range; and standard deviation. Box plots are also shown for selected machining conditions. The problems arising during signal recording with a mean emissivity coefficient ε = 0.13, a value which is dedicated during machining magnesium alloys, are discussed in detail. Chip temperatures obtained in the tests do not exceed approx. 420 °C. Therefore, the dry rough milling process carried out with carbide tools with different blade geometries can be considered safe for a wide range of machining parameters. The proposed methodology of chip temperature measurement and result processing is a new and effective approach to safety assessment in the dry milling of magnesium alloys. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
24 pages, 358 KiB  
Article
Existence of Solutions to a System of Fractional q-Difference Boundary Value Problems
by Alexandru Tudorache and Rodica Luca
Mathematics 2024, 12(9), 1335; https://doi.org/10.3390/math12091335 (registering DOI) - 27 Apr 2024
Abstract
We are investigating the existence of solutions to a system of two fractional q-difference equations containing fractional q-integral terms, subject to multi-point boundary conditions that encompass q-derivatives and fractional q-derivatives of different orders. In our main results, we rely [...] Read more.
We are investigating the existence of solutions to a system of two fractional q-difference equations containing fractional q-integral terms, subject to multi-point boundary conditions that encompass q-derivatives and fractional q-derivatives of different orders. In our main results, we rely on various fixed point theorems, such as the Leray–Schauder nonlinear alternative, the Schaefer fixed point theorem, the Krasnosel’skii fixed point theorem for the sum of two operators, and the Banach contraction mapping principle. Finally, several examples are provided to illustrate our findings. Full article
19 pages, 1831 KiB  
Article
Iron Supplementation Increases Tumor Burden and Alters Protein Expression in a Mouse Model of Human Intestinal Cancer
by Ian X. Swain and Adam M. Kresak
Nutrients 2024, 16(9), 1316; https://doi.org/10.3390/nu16091316 (registering DOI) - 27 Apr 2024
Abstract
Iron supplements are widely consumed. However, excess iron may accelerate intestinal tumorigenesis. To determine the effect of excess iron on intestinal tumor burden and protein expression changes between tumor and normal tissues, ApcMin/+ mice were fed control (adequate) and excess iron (45 [...] Read more.
Iron supplements are widely consumed. However, excess iron may accelerate intestinal tumorigenesis. To determine the effect of excess iron on intestinal tumor burden and protein expression changes between tumor and normal tissues, ApcMin/+ mice were fed control (adequate) and excess iron (45 and 450 mg iron/kg diet, respectively; n = 9/group) for 10 wk. Tumor burden was measured, and two-dimensional fluorescence difference gel electrophoresis was used to identify differentially expressed proteins in tumor and normal intestinal tissues. There was a significant increase (78.3%; p ≤ 0.05) in intestinal tumor burden (mm2/cm) with excess iron at wk 10. Of 980 analyzed protein spots, 69 differentially expressed (p ≤ 0.05) protein isoforms were identified, representing 55 genes. Of the isoforms, 56 differed (p ≤ 0.05) between tumor vs. normal tissues from the adequate iron group and 23 differed (p ≤ 0.05) between tumors from the adequate vs. excess iron. Differentially expressed proteins include those involved in cell integrity and adaptive response to reactive oxygen species (including, by gene ID: ANPEP, DPP7, ITGB1, PSMA1 HSPA5). Biochemical pathway analysis found that iron supplementation modulated four highly significant (p ≤ 0.05) functional networks. These findings enhance our understanding of interplay between dietary iron and intestinal tumorigenesis and may help develop more specific dietary guidelines regarding trace element intake. Full article
(This article belongs to the Section Micronutrients and Human Health)
16 pages, 335 KiB  
Review
Progress in Rice Breeding Based on Genomic Research
by Xingye Yang, Shicong Yu, Shen Yan, Hao Wang, Wei Fang, Yanqing Chen, Xiaoding Ma and Longzhi Han
Genes 2024, 15(5), 564; https://doi.org/10.3390/genes15050564 (registering DOI) - 27 Apr 2024
Abstract
The role of rice genomics in breeding progress is becoming increasingly important. Deeper research into the rice genome will contribute to the identification and utilization of outstanding functional genes, enriching the diversity and genetic basis of breeding materials and meeting the diverse demands [...] Read more.
The role of rice genomics in breeding progress is becoming increasingly important. Deeper research into the rice genome will contribute to the identification and utilization of outstanding functional genes, enriching the diversity and genetic basis of breeding materials and meeting the diverse demands for various improvements. Here, we review the significant contributions of rice genomics research to breeding progress over the last 25 years, discussing the profound impact of genomics on rice-genome sequencing, functional-gene exploration, and novel breeding methods, and we provide valuable insights for future research and breeding practices. Full article
(This article belongs to the Special Issue Genomic Studies of Plant Breeding)
11 pages, 580 KiB  
Systematic Review
Laparoscopic Ligation of the Inferior Mesenteric Artery: A Systematic Review of an Emerging Trend for Addressing Type II Endoleak Following Endovascular Aortic Aneurysm Repair
by Konstantinos Roditis, Paraskevi Tsiantoula, Nikolaos-Nektarios Giannakopoulos, Afroditi Antoniou, Vasileios Papaioannou, Sofia Tzamtzidou, Dimitra Manou, Konstantinos G. Seretis, Theofanis T. Papas and Nikolaos Bessias
J. Clin. Med. 2024, 13(9), 2584; https://doi.org/10.3390/jcm13092584 (registering DOI) - 27 Apr 2024
Abstract
Background/Objectives: this systematic review aims to explore the efficacy and safety of the laparoscopic ligation of the inferior mesenteric artery (IMA) as an emerging trend for addressing a type II endoleak following endovascular aortic aneurysm repair (EVAR). Methods: A comprehensive literature [...] Read more.
Background/Objectives: this systematic review aims to explore the efficacy and safety of the laparoscopic ligation of the inferior mesenteric artery (IMA) as an emerging trend for addressing a type II endoleak following endovascular aortic aneurysm repair (EVAR). Methods: A comprehensive literature search was conducted across several databases including Medline, Scopus, and the Cochrane Central Register of Controlled Trials, adhering to the PRISMA guidelines. The search focused on articles reporting on the laparoscopic ligation of the IMA for the treatment of a type II endoleak post-EVAR. Data were extracted regarding study characteristics, patient demographics, technical success rates, postoperative outcomes, and follow-up results. Results: Our analysis included ten case studies and two retrospective cohort studies, comprising a total of 26 patients who underwent a laparoscopic ligation of the IMA between 2000 and 2023. The mean age of the cohort was 72.3 years, with a male predominance (92.3%). The mean AAA diameter at the time of intervention was 69.7 mm. The technique demonstrated a high technical success rate of 92.3%, with a mean procedure time of 118.4 min and minimal blood loss. The average follow-up duration was 19.9 months, with 73% of patients experiencing regression of the aneurysmal sac, and no reports of an IMA-related type II endoleak during the follow-up period. Conclusions: The laparoscopic ligation of the IMA for a type II endoleak following EVAR presents a promising, minimally invasive alternative with high technical success rates and favorable postoperative outcomes. Despite its potential advantages, including reduced contrast agent use and radiation exposure, its application remains limited to specialized centers. The findings suggest the need for further research in larger prospective studies to validate the effectiveness of this procedure and potentially broaden its clinical adoption. Full article
(This article belongs to the Special Issue Vascular Surgery: Recent Developments and Emerging Trends)
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17 pages, 49973 KiB  
Article
Real-Time Multi-Person Video Synthesis with Controllable Prior-Guided Matting
by Aoran Chen, Hai Huang, Yueyan Zhu and Junsheng Xue
Sensors 2024, 24(9), 2795; https://doi.org/10.3390/s24092795 (registering DOI) - 27 Apr 2024
Abstract
In order to enhance the matting performance in multi-person dynamic scenarios, we introduce a robust, real-time, high-resolution, and controllable human video matting method that achieves state of the art on all metrics. Unlike most existing methods that perform video matting frame by frame [...] Read more.
In order to enhance the matting performance in multi-person dynamic scenarios, we introduce a robust, real-time, high-resolution, and controllable human video matting method that achieves state of the art on all metrics. Unlike most existing methods that perform video matting frame by frame as independent images, we design a unified architecture using a controllable generation model to solve the problem of the lack of overall semantic information in multi-person video. Our method, called ControlMatting, uses an independent recurrent architecture to exploit temporal information in videos and achieves significant improvements in temporal coherence and detailed matting quality. ControlMatting adopts a mixed training strategy comprised of matting and a semantic segmentation dataset, which effectively improves the semantic understanding ability of the model. Furthermore, we propose a novel deep learning-based image filter algorithm that enforces our detailed augmentation ability on both matting and segmentation objectives. Our experiments have proved that prior information about the human body from the image itself can effectively combat the defect masking problem caused by complex dynamic scenarios with multiple people. Full article
(This article belongs to the Special Issue Computer Vision and Virtual Reality: Technologies and Applications)
53 pages, 777 KiB  
Systematic Review
The Role of Diet in the Cardiovascular Health of Childhood Cancer Survivors—A Systematic Review
by Ruijie Li, Alan R. Barker, Dimitris Vlachopoulos, Dewi Paris, Christina Schindera, Fabiën N. Belle and Raquel Revuelta Iniesta
Nutrients 2024, 16(9), 1315; https://doi.org/10.3390/nu16091315 (registering DOI) - 27 Apr 2024
Abstract
Background: Childhood cancer survivors (CCSs) face an increased risk of cardiovascular disease (CVD). This systematic review aims to provide the first synthesis of observational and interventional studies on the relationship between diet and cardiovascular health in CCSs. Methods: A comprehensive search was conducted [...] Read more.
Background: Childhood cancer survivors (CCSs) face an increased risk of cardiovascular disease (CVD). This systematic review aims to provide the first synthesis of observational and interventional studies on the relationship between diet and cardiovascular health in CCSs. Methods: A comprehensive search was conducted for studies published between 1990 and July 2023 in PubMed, MEDLINE, CINAHL, Child Development & Adolescent Studies, and Cochrane Library. Eligible studies included observational and interventional studies examining the associations or effects of dietary factors on CVD incidence, cardiac dysfunction, or CVD risk factors in CCSs diagnosed before age 25 years. Results: Ten studies met the inclusion criteria (nine observational and one interventional). Collectively, they comprised 3485 CCSs (male, 1734; female, 1751). The outcomes examined across observational studies included characteristics of obesity, diabetes biomarkers, hypertension indicators, dyslipidaemia biomarkers, and metabolic syndrome. The evidence suggested that greater adherence to healthy diets was associated with lower body mass index, blood pressure, glucose, and triglycerides and higher high-density lipoprotein cholesterol. The 12-week lifestyle intervention study in childhood leukaemia survivors found no impact on obesity indicators. Conclusion: The review results indicate the potentially protective effects of healthy diets. However, the available research remains preliminary and limited, underscoring the need for more rigorous, adequately powered studies. Full article
(This article belongs to the Section Pediatric Nutrition)
19 pages, 3708 KiB  
Article
Research on Pattern Dynamics Behavior of a Fractional Vegetation-Water Model in Arid Flat Environment
by Xiao-Long Gao, Hao-Lu Zhang, Yu-Lan Wang and Zhi-Yuan Li
Fractal Fract. 2024, 8(5), 264; https://doi.org/10.3390/fractalfract8050264 (registering DOI) - 27 Apr 2024
Abstract
In order to stop and reverse land degradation and curb the loss of biodiversity, the United Nations 2030 Agenda for Sustainable Development proposes to combat desertification. In this paper, a fractional vegetation–water model in an arid flat environment is studied. The pattern behavior [...] Read more.
In order to stop and reverse land degradation and curb the loss of biodiversity, the United Nations 2030 Agenda for Sustainable Development proposes to combat desertification. In this paper, a fractional vegetation–water model in an arid flat environment is studied. The pattern behavior of the fractional model is much more complex than that of the integer order. We study the stability and Turing instability of the system, as well as the Hopf bifurcation of fractional order α, and obtain the Turing region in the parameter space. According to the amplitude equation, different types of stationary mode discoveries can be obtained, including point patterns and strip patterns. Finally, the results of the numerical simulation and theoretical analysis are consistent. We find some novel fractal patterns of the fractional vegetation–water model in an arid flat environment. When the diffusion coefficient, d, changes and other parameters remain unchanged, the pattern structure changes from stripes to spots. When the fractional order parameter, β, changes, and other parameters remain unchanged, the pattern structure becomes more stable and is not easy to destroy. The research results can provide new ideas for the prevention and control of desertification vegetation patterns. Full article
(This article belongs to the Section Numerical and Computational Methods)
18 pages, 5033 KiB  
Article
Development of Chitosan-Based Films Incorporated with Chestnut Flower Essential Oil That Possess Good Anti-Ultraviolet Radiation and Antibacterial Effects for Banana Storage
by Yanfei Liu, Jingyuan Zhang, Fei Peng, Kui Niu, Wenlong Hou, Bin Du and Yuedong Yang
Coatings 2024, 14(5), 548; https://doi.org/10.3390/coatings14050548 (registering DOI) - 27 Apr 2024
Abstract
New and valuable packaging materials, with high biocompatibility and biodegradability, have garnered attention in recent years. The aim of this study was to investigate the physicochemical characterization and biological activities of chitosan (CH)-based composite films with the incorporation of chestnut flower essential oil [...] Read more.
New and valuable packaging materials, with high biocompatibility and biodegradability, have garnered attention in recent years. The aim of this study was to investigate the physicochemical characterization and biological activities of chitosan (CH)-based composite films with the incorporation of chestnut flower essential oil (CFEO). The composite films were prepared by the casting method and characterized in terms of structural, morphological, and mechanical properties via FT-IR, XRD, UV, SEM, AFM, and TGA. Antibacterial properties were investigated using Staphylococcus aureus, Escherichia coli, and Calletotrichum musae. Antioxidant capabilities were measured by DPPH assay. The results proved the significantly increased water vapor permeability (WVP), heat resistance, and antibacterial and antioxidant capabilities of CH-CFEO films. The incorporation of CH and CFEO enhanced UV blocking, which made the film shield almost all UV light. Films with a tensile strength of 6.37 ± 0.41 MPa and an elongation at break of 22.57 ± 0.35% were obtained with 6 mg mL−1 of CFEO. Subsequently, banana preservation experiments also confirmed that the composite films could effectively extend shelf life through reducing weight loss. These desirable performances enable our newly developed composite films to be a remarkable packaging material to become alternatives to traditional petroleum-based food-packaging materials and solve the fresh fruit preservation dilemma. Full article
(This article belongs to the Special Issue Functional Coatings in Postharvest Fruit and Vegetables)
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15 pages, 7043 KiB  
Article
Hydrodynamic Interactions and Enhanced Energy Harnessing amongst Many WEC Units in Large-Size Wave Parks
by Xinyuan Shao, Jonas W. Ringsberg, Hua-Dong Yao, Uday Rajdeep Sakleshpur Lokesh Gowda, Hrishikesh Nitin Khedkar and Jørgen Hals Todalshaug
J. Mar. Sci. Eng. 2024, 12(5), 730; https://doi.org/10.3390/jmse12050730 (registering DOI) - 27 Apr 2024
Abstract
Interactions between wave energy converters (WECs) can significantly affect the overall energy-harnessing performance of a wave park. Although large-size wave parks with many WEC units are commonly considered in practical applications, it is challenging to simulate such parks due to huge computational costs. [...] Read more.
Interactions between wave energy converters (WECs) can significantly affect the overall energy-harnessing performance of a wave park. Although large-size wave parks with many WEC units are commonly considered in practical applications, it is challenging to simulate such parks due to huge computational costs. This paper presents a numerical model that uses the boundary element method (BEM) to simulate wave parks. Each wave energy converter (WEC) was modelled as a comprehensive system, including WEC buoys, power take-off, and mooring systems, with hydrodynamic interactions included. Two classical layouts for arranging 16 units were simulated using this numerical model. The energy-harnessing performance of these array layouts was analyzed for both regular waves and a selection of irregular sea state conditions with different wave directions, wave heights, wave periods and water depths. For each layout, three WEC separation distances were studied. An increase of up to 16% in the power performance of the WEC under regular waves was observed, which highlights the importance of interaction effects. Full article
(This article belongs to the Special Issue Development and Utilization of Offshore Renewable Energy)
20 pages, 831 KiB  
Article
Definition of Exergetic Efficiency in the Main and Emerging Thermal Desalination Technologies: A Proposal
by Nenna Arakcheeva El Kori, Ana M. Blanco-Marigorta and Noemi Melián Martel
Water 2024, 16(9), 1254; https://doi.org/10.3390/w16091254 (registering DOI) - 27 Apr 2024
Abstract
Increasing attention is being given to reduce the specific energy consumption in desalination processes, which translates into greater use of exergy analysis. An exergetic analysis provides relevant information related to the influence of the efficiency of a single component in the global plant [...] Read more.
Increasing attention is being given to reduce the specific energy consumption in desalination processes, which translates into greater use of exergy analysis. An exergetic analysis provides relevant information related to the influence of the efficiency of a single component in the global plant performance and in the exergy cost of the product. Therefore, an exergy analysis identifies the main improvement potentials in a productive thermodynamic process. Related to desalination technologies, many previous papers deal with the calculation of the parameters involved in the exergy analysis, the exergetic efficiency of different processes, plants, and technologies among them. However, different approaches for formulating the exergetic efficiency have been suggested in the literature, often without sufficient understanding and consistency. In this work, these formulations, applied to the main desalination components and processes, are compared and critically reviewed. Two definitions of exergy efficiency are applied to the desalination components of the three main thermal desalination processes (multieffect distillation–thermal vapour compression, multistage flash distillation, and direct-contact membrane distillation). The results obtained for the exergy efficiency of the MED-TVC, MSF, and DCMD processes for the input–output approach are 21.35%, 17.08%, and 1.28%, respectively, compared to the consumed–produced approach that presented 3.1%, 1.58%, and 0.37%, respectively. The consumed–produced approach seems to better fit the thermodynamic behaviour of thermal desalination systems. Full article
(This article belongs to the Special Issue Advanced Desalination Technologies for Water Treatment)
17 pages, 4499 KiB  
Article
Particle-Filter-Based Fault Diagnosis for the Startup Process of an Open-Cycle Liquid-Propellant Rocket Engine
by Jihyoung Cha, Sangho Ko and Soon-Young Park
Sensors 2024, 24(9), 2798; https://doi.org/10.3390/s24092798 (registering DOI) - 27 Apr 2024
Abstract
This study introduces a fault diagnosis algorithm based on particle filtering for open-cycle liquid-propellant rocket engines (LPREs). The algorithm serves as a model-based method for the startup process, accounting for more than 30% of engine failures. Similar to the previous fault detection and [...] Read more.
This study introduces a fault diagnosis algorithm based on particle filtering for open-cycle liquid-propellant rocket engines (LPREs). The algorithm serves as a model-based method for the startup process, accounting for more than 30% of engine failures. Similar to the previous fault detection and diagnosis (FDD) algorithm for the startup process, the algorithm in this study is composed of a nonlinear filter to generate residuals, a residual analysis, and a multiple-model (MM) approach to detect and diagnose faults from the residuals. In contrast to the previous study, this study makes use of the modified cumulative sum (CUSUM) algorithm, widely used in change-detection monitoring, and a particle filter (PF), which is theoretically the most accurate nonlinear filter. The algorithm is confirmed numerically using the CUSUM and MM methods. Subsequently, the FDD algorithm is compared with an algorithm from a previous study using a Monte Carlo simulation. Through a comparative analysis of algorithmic performance, this study demonstrates that the current PF-based FDD algorithm outperforms the algorithm based on other nonlinear filters. Full article
(This article belongs to the Section Fault Diagnosis & Sensors)
18 pages, 5414 KiB  
Article
Dynamic Doppler Characteristics of Maritime Airborne Corner Reflector
by Lingang Wu, Shengliang Hu, Chengxu Feng, Yasong Luo, Zhong Liu and Li Lin
J. Mar. Sci. Eng. 2024, 12(5), 727; https://doi.org/10.3390/jmse12050727 (registering DOI) - 27 Apr 2024
Abstract
The maritime airborne corner reflector (ACR) is a radar reflector that can measure wind speed in an unknown sea area in real time over a long distance. To improve our understanding of how the ACR works, we investigated the Doppler characteristics of the [...] Read more.
The maritime airborne corner reflector (ACR) is a radar reflector that can measure wind speed in an unknown sea area in real time over a long distance. To improve our understanding of how the ACR works, we investigated the Doppler characteristics of the ACR for the first time from a dynamic perspective. First, we constructed a radar echo signal model of the ACR. Then, we obtained the dynamic Doppler characteristics through pulse Doppler processing and discussed the special phenomenon of Doppler broadening. Finally, we proposed a rectangular window decomposition method to analyze the inner principle of the Doppler broadening phenomenon in more detail. In conclusion, this study provides valuable insights into the Doppler characterization of an ACR from a dynamic viewpoint, which contributes to enriching the basic theory of this equipment. Full article
(This article belongs to the Special Issue Ocean Observations)
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13 pages, 8405 KiB  
Article
Rapid Fabrication of Yttrium Aluminum Garnet Microhole Array Based on Femtosecond Bessel Beam
by Heng Yang, Yuan Yu, Tong Zhang, Shufang Ma, Lin Chen, Bingshe Xu and Zhiyong Wang
Photonics 2024, 11(5), 408; https://doi.org/10.3390/photonics11050408 (registering DOI) - 27 Apr 2024
Abstract
High-aspect-ratio microholes, the fundamental building blocks for microfluidics, optical waveguides, and other devices, find wide applications in aerospace, biomedical, and photonics fields. Yttrium aluminum garnet (YAG) crystals are commonly used in optical devices due to their low stress, hardness, and excellent chemical stability. [...] Read more.
High-aspect-ratio microholes, the fundamental building blocks for microfluidics, optical waveguides, and other devices, find wide applications in aerospace, biomedical, and photonics fields. Yttrium aluminum garnet (YAG) crystals are commonly used in optical devices due to their low stress, hardness, and excellent chemical stability. Therefore, finding efficient fabrication methods to produce high-quality microholes within YAG crystals is crucial. The Bessel beam, characterized by a uniform energy distribution along its axis and an ultra-long depth of focus, is highly suitable for creating high-aspect-ratio structures. In this study, an axicon lens was used to shape the spatial profile of a femtosecond laser into a Bessel beam. Experimental verification showed a significant improvement in the high aspect ratio of the microholes produced in YAG crystals using the femtosecond Bessel beam. This study investigated the effects of the power and defocus parameters of single-pulse Bessel beams on microhole morphology and size, and microhole units with a maximum aspect ratio of more than 384:1 were obtained. Based on these findings, single-pulse femtosecond Bessel processing parameters were optimized, and an array of 181 × 181 microholes in a 400 μm thick YAG crystal was created in approximately 13.5 min. The microhole array had a periodicity of 5 μm and a unit aspect ratio of 315:1, with near-circular top and subface apertures and high repeatability. Full article
(This article belongs to the Special Issue Laser Processing and Modification of Materials)
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15 pages, 3296 KiB  
Article
In Vitro Evaluation of Phytobiotic Mixture Antibacterial Potential against Enterococcus spp. Strains Isolated from Broiler Chicken
by Karolina Wódz, Karolina A. Chodkowska, Hubert Iwiński, Henryk Różański and Jakub Wojciechowski
Int. J. Mol. Sci. 2024, 25(9), 4797; https://doi.org/10.3390/ijms25094797 (registering DOI) - 27 Apr 2024
Abstract
Enterococcus spp. are normal intestinal tract microflorae found in poultry. However, the last decades have shown that several species, e.g., Enterococcus cecorum, have become emerging pathogens in broilers and may cause numerous losses in flocks. In this study, two combinations (H1 and [...] Read more.
Enterococcus spp. are normal intestinal tract microflorae found in poultry. However, the last decades have shown that several species, e.g., Enterococcus cecorum, have become emerging pathogens in broilers and may cause numerous losses in flocks. In this study, two combinations (H1 and H2) of menthol, 1,8-cineol, linalool, methyl salicylate, γ-terpinene, p-cymene, trans-anethole, terpinen-4-ol and thymol were used in an in vitro model, analyzing its effectiveness against the strains E. cecorum, E. faecalis, E. faecium, E. hirae and E. gallinarum isolated from broiler chickens from industrial farms. To identify the isolated strains classical microbiological methods and VITEK 2 GP cards were used. Moreover for E. cecorum a PCR test was used.. Antibiotic sensitivity (MIC) tests were performed for all the strains. For the composition H1, the effective dilution for E. cecorum and E. hirae strains was 1:512, and for E. faecalis, E. faecium and E. gallinarum, 1:1024. The second mixture (H2) showed very similar results with an effectiveness at 1:512 for E. cecorum and E. hirae and 1:1024 for E. faecalis, E. faecium and E. gallinarum. The presented results suggest that the proposed composition is effective against selected strains of Enterococcus in an in vitro model, and its effect is comparable to classical antibiotics used to treat this pathogen in poultry. This may suggest that this product may also be effective in vivo and provide effective support in the management of enterococcosis in broiler chickens. Full article
(This article belongs to the Special Issue Recent Research on Antimicrobial Agents)
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16 pages, 5545 KiB  
Article
The Effect of Laser Remelting during SLM on Microstructure and Mechanical Properties of CoCrFeNiNb0.25
by Zhiyuan Yang, Chan Guo, Tao Sun, Jinpeng Hu, Xiaomei Feng and Yifu Shen
Materials 2024, 17(9), 2061; https://doi.org/10.3390/ma17092061 (registering DOI) - 27 Apr 2024
Abstract
A sub-eutectic high-entropy alloy composed of CoCrFeNiNb0.25 was prepared using a combination of mechanical powder mixing and selective laser melting (SLM). The mechanical properties of the alloy were enhanced by employing an interlayer laser remelting process. This study demonstrates the feasibility of [...] Read more.
A sub-eutectic high-entropy alloy composed of CoCrFeNiNb0.25 was prepared using a combination of mechanical powder mixing and selective laser melting (SLM). The mechanical properties of the alloy were enhanced by employing an interlayer laser remelting process. This study demonstrates the feasibility of using mechanical mixing and SLM to form an CoCrFeNiNb0.25 alloy. The interlayer laser remelting process can effectively promote the melting of Nb particles introduced by mechanical mixing, release the stresses near the unfused Nb particles, and reduce their degradation of the specimen properties. The results indicate that the CoCrFeNiNb0.25 alloy, prepared using the interlayer laser remelting process, had an average microhardness of 376 HV, a tensile strength of 974 MPa, and an elongation at break of 10.51%. This process offers a viable approach for rapidly adjusting the composition of high-entropy alloys for SLM forming. Full article
18 pages, 590 KiB  
Article
Quasi-Projective Synchronization of Discrete-Time Fractional-Order Complex-Valued BAM Fuzzy Neural Networks via Quantized Control
by Yingying Xu, Hongli Li, Jikai Yang and Long Zhang
Fractal Fract. 2024, 8(5), 263; https://doi.org/10.3390/fractalfract8050263 (registering DOI) - 27 Apr 2024
Abstract
In this paper, we ponder a kind of discrete-time fractional-order complex-valued fuzzy BAM neural network. Firstly, in order to guarantee the quasi-projective synchronization of the considered networks, an original quantitative control strategy is designed. Next, by virtue of the relevant definitions and properties [...] Read more.
In this paper, we ponder a kind of discrete-time fractional-order complex-valued fuzzy BAM neural network. Firstly, in order to guarantee the quasi-projective synchronization of the considered networks, an original quantitative control strategy is designed. Next, by virtue of the relevant definitions and properties of the Mittag-Leffler function, we propose a novel discrete-time fractional-order Halanay inequality, which is more efficient for disposing of the discrete-time fractional-order models with time delays. Then, based on the new lemma, fractional-order h-difference theory, and comparison principle, we obtain some easy-to-verify synchronization criteria in terms of algebraic inequalities. Finally, numerical simulations are provided to check the accuracy of the proposed theoretical results. Full article

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