| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Cache Misses and the Recovery of the Full AES 256 Key |
Samira Briongos / Pedro Malagón / Juan-Mariano de Goyeneche / Jose M. Moya |
Appl. Sci. 2019, 9(5), 944; |
https://doi.org/10.3390/app9050944 |
The CPU cache is a hardware element that leaks significant information about the software running on the CPU. Particularly, any application performing sequences of memory access that depend on sensitive information, such as private keys, is susceptible to suffer a cache attack, which would reveal this information. In most cases, side-channel cache attacks do not require any specific permission and just need access to a shared cache. This fact, combined with the spread of cloud computing, where the infrastructure is shared between different customers, has made these attacks quite popular. Traditionally, cache attacks against AES use the information about the victim to access an address. In contrast, we show that using non-access provides much more information and demonstrate that the power of cache attacks has been underestimated during these last years. This novel approach is applicable to existing attacks: Prime+Probe, Flush+Reload, Flush+Flush and Prime+Abort. In all cases, using cache misses as source of information, we could retrieve the 128-bit AES key with a reduction in the number of samples of between 93% and 98% compared to the traditional approach. Further, this attack was adapted and extended in what we call the encryption-by-decryption cache attack (EBD), to obtain a 256-bit AES key. In the best scenario, our approach obtained the 256 bits of the key of the OpenSSL AES T-table-based implementation using fewer than 10,000 samples, i.e., 135 milliseconds, proving that AES-256 is only about three times more complex to attack than AES-128 via cache attacks. Additionally, the proposed approach was successfully tested in a cross-VM scenario. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Microstructure and Mechanical Properties of Cement Mortar Containing Phase Change Materials |
Hyun-Do Yun / Jong-Won Lee / Young-Il Jang / Seok-Joon Jang / Wonchang Choi |
Appl. Sci. 2019, 9(5), 943; |
https://doi.org/10.3390/app9050943 |
This paper presents an investigation of the characterization of cement mortar containing phase change materials (PCMs) in order to control the development of hydration heat. The study examined microstructural characteristics and properties of cement mortar with PCMs such as flow, compressive strength, and flexural strength. This research involved two types of PCM and up to 15% cement added to cement mortar mixtures. The two types of PCM used in this study are PCM with barium (PCM-Ba) and PCM with strontium (PCM-Sr). The experimental results indicate that both the incremental temperature rise and the maximum temperature release time of PCM up to 5% addition are delayed. Both PCM-Ba and PCM-Sr are effective in reducing the development of hydration heat. The microstructural analysis results show that the crystalloid content of cement mortar without PCMs is about 3% more from cement mortar with PCMs, regardless of the type of PCMs used, and that no significant difference is evident in the formation of crystals between cement mortar with and without PCMs. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Landslide Susceptibility Mapping Based on Random Forest and Boosted Regression Tree Models, and a Comparison of Their Performance |
Soyoung Park / Jinsoo Kim |
Appl. Sci. 2019, 9(5), 942; |
https://doi.org/10.3390/app9050942 |
This study aims to analyze and compare landslide susceptibility at Woomyeon Mountain, South Korea, based on the random forest (RF) model and the boosted regression tree (BRT) model. Through the construction of a landslide inventory map, 140 landslide locations were found. Among these, 42 (30%) were reserved to validate the model after 98 (70%) had been selected at random for model training. Fourteen landslide explanatory variables related to topography, hydrology, and forestry factors were considered and selected, based on the results of information gain for the modeling. The results were evaluated and compared using the receiver operating characteristic curve and statistical indices. The analysis showed that the RF model was better than the BRT model. The RF model yielded higher specificity, overall accuracy, and kappa index than the BRT model. In addition, the RF model, with a prediction rate of 0.865, performed slightly better than the BRT model, which had a prediction rate of 0.851. These results indicate that the landslide susceptibility maps (LSMs) produced in this study had good performance for predicting the spatial landslide distribution in the study area. These LSMs could be helpful for establishing mitigation strategies and for land use planning. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Numerical Analysis of Flow in Building Arrangement: Computational Domain Discretization |
Marcin Sosnowski / Renata Gnatowska / Karolina Grabowska / Jaros??aw Krzywański / Arkadiusz Jamrozik |
Appl. Sci. 2019, 9(5), 941; |
https://doi.org/10.3390/app9050941 |
The progress in environmental investigations such as the analysis of building arrangements in an urban environment could not have been expanded without the use of computational fluid dynamics (CFD) as a research tool. The rapid development of numerical models results in improved correlations to results obtained with real data. Unfortunately, the computational domain discretization is a crucial step in CFD analysis which significantly influences the accuracy of the generated results. Hence an innovative approach to computational domain discretization using polyhedral elements is proposed. The results are compared to commonly applied tetrahedral and hexahedral elements as well as experimental results of particle image velocimetry (PIV). The performed research proves that the proposed method is promising as it allows for the reduction of both the numerical diffusion of the mesh as well as the time cost of preparing the model for calculation. In consequence, the presented approach allows for better results in less time. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Classification of Pulmonary CT Images by Using Hybrid 3D-Deep Convolutional Neural Network Architecture |
Huseyin Polat / Homay Danaei Mehr |
Appl. Sci. 2019, 9(5), 940; |
https://doi.org/10.3390/app9050940 |
Lung cancer is the most common cause of cancer-related deaths worldwide. Hence, the survival rate of patients can be increased by early diagnosis. Recently, machine learning methods on Computed Tomography (CT) images have been used in the diagnosis of lung cancer to accelerate the diagnosis process and assist physicians. However, in conventional machine learning techniques, using handcrafted feature extraction methods on CT images are complicated processes. Hence, deep learning as an effective area of machine learning methods by using automatic feature extraction methods could minimize the process of feature extraction. In this study, two Convolutional Neural Network (CNN)-based models were proposed as deep learning methods to diagnose lung cancer on lung CT images. To investigate the performance of the two proposed models (Straight 3D-CNN with conventional softmax and hybrid 3D-CNN with Radial Basis Function (RBF)-based SVM), the altered models of two-well known CNN architectures (3D-AlexNet and 3D-GoogleNet) were considered. Experimental results showed that the performance of the two proposed models surpassed 3D-AlexNet and 3D-GoogleNet. Furthermore, the proposed hybrid 3D-CNN with SVM achieved more satisfying results (91.81%, 88.53% and 91.91% for accuracy rate, sensitivity and precision respectively) compared to straight 3D-CNN with softmax in the diagnosis of lung cancer. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Accuracy and Inter-Unit Reliability of Ultra-Wide-Band Tracking System in Indoor Exercise |
Alejandro Bastida-Castillo / Carlos David Gómez-Carmona / Ernesto De la Cruz-Sánchez / Xavier Reche-Royo / Sergio José Ibá??ez / José Pino Ortega |
Appl. Sci. 2019, 9(5), 939; |
https://doi.org/10.3390/app9050939 |
The purpose of this study was to assess the accuracy of positional data and the inter-unit reliability of an ultra-wide-band (UWB) tracking system. Four well-trained males performed five courses designed for the analysis of x- and y-coordinate accuracy analysis, specifically related to the positional distance variation between the UWB data and the fixed reference lines of a basketball court. This was achieved using geographic information system (GIS) mapping software that calculated, for each interval and participant, the distance from the main axis of displacement and from the opposite side of the court each 0.5 s (x and y coordinate). The accuracy of the results was satisfactory, with a mean absolute error of all estimations for the x-position of 5.2 ± 3.1 cm and for the y-position of 5.8 ± 2.3 cm. Regarding inter-unit reliability, the intra-class correlation coefficient (ICC) value was high for the x-coordinate (0.65) and very high for the y-coordinate (0.85). The main findings of the study were: (i) The accuracy of UWB tracking systems can be considered suitable for practical applications in sport analyses; (ii) position estimations are very precise and acceptable for tactical analyses; (iii) the error of the position estimations does not change significantly across different courses; and (iv) the use of different devices does not significantly affect the measurement error. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Exploring the Utility of 3-D-printed Laboratory Equipment |
Yifei Zhou / Chuyun Duan / Iyll-Joon Doh / Euiwon Bae |
Appl. Sci. 2019, 9(5), 937; |
https://doi.org/10.3390/app9050937 |
Many laboratories utilize different types of opto-mechanical positioning devices in their experiments. Such devices include lateral stages, which provide 1-dimenstional translational movement, 3-dimensional translation stages, and laboratory jacks, which provide a convenient way of changing the vertical position of a sample. Recent advances in and affordability of 3-D printing have opened up a variety of possibilities, not only providing versatile and custom-designed laboratory equipment but also reducing the cost of constructing typical laboratory opto-mechanical positioning stages. Here, we present the possibility of printing typical linear stages, thereby constructing a full XYZ stage. In addition, a vertical laboratory jack, which utilizes a scissor format, has also been printed using polylactic acid (PLA) filament. The design of these systems required modeling the strength of material to estimate the deflection, which was conducted by finite element analysis. The effectiveness of the proposed 3-D-printed positioning devices was tested by measuring the stroke and the repeatability. As an example of application, a multispectral reflection imaging device was constructed with the help of 3-D-printed linear stages and a laboratory scissor jack. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
The Effect of Selected Additives on the Oil Uptake and Quality Parameters of Fried Instant Noodles |
Katarzyna Marciniak-Lukasiak / Anna Zbikowska / Agata Marzec / Mariola Kozlowska |
Appl. Sci. 2019, 9(5), 936; |
https://doi.org/10.3390/app9050936 |
The scope of the paper includes the analysis of various quality parameters of fried instant noodles depending on the type and amount of the additive added to the basic recipe. For the analyzed instant noodles, the effect of hydroxypropylmethylcellulose (HPMC), microcrystalline cellulose (MCG), maltodextrin, and psyllium on the quality parameters (oil uptake, moisture, water activity, color, and acoustics) were determined. Results show that the quality parameters of instant noodles significantly depend on the type and amount of additives. The addition of HPMC and MCG resulted in decrease absorption, while the use of maltodextrin and psyllium increased the fat absorbed during frying. There is a significant relationship between the type of additive and the color of instant noodles. Color brightening was observed for instant noodles with the HPMC and MCG, while the addition of maltodextrin and psyllium contributed in the darkening of instant noodles (reduction of the L* parameter). The type of additives significantly influenced the texture of the instant noodles. The samples with a 3% addition of maltodextrin had a softer texture than the control sample, while the instant noodles with the HPMC, MCG, and Psyllium were characterized by a harder texture. For instant noodles with the addition of HPMC, MCG, and Psyllium larger number of acoustic events and higher breaking force were observed than for the control one. The frying temperature significantly influenced the texture of analyzed instant noodles (acoustic and mechanical properties). Increasing frying temperature from 160–170 °C caused a significant increase in acoustic descriptors and force. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Morphology-Controlled Versatile One-Pot Synthesis of Hydrophobic Gold Nanodots, Nanobars, Nanorods, and Nanowires and Their Applications in Surface-Enhanced Raman Spectroscopy |
Jing Neng / Chen Xiang / Kan Jia / Xiaohua Nie / Peilong Sun |
Appl. Sci. 2019, 9(5), 935; |
https://doi.org/10.3390/app9050935 |
Many previously reported syntheses of gold nanoparticles required lengthy reaction times, complicated operations, high temperatures, or multi-step manipulations. In this work, a morphology-controlled versatile one-pot synthesis of hydrophobic gold nanodots, nanobars, nanorods, and nanowires has been developed. A series of gold nanomaterials ranging from round nanodots, short nanobars, and long nanorods to ultrathin and ultralong nanowires (diameter <2 nm, length >2 μm) have been readily prepared by simply adjusting the feeding ratio of chloroauric acid to oleylamine, oleic acid, and triphenylsilane. The silk-like ultralong and ultrathin nanowires were found to have a single crystalline structure and may have significant potential applications in microelectronics and biosensors. Large sizes of gold spherical nanoparticles were obtained from gold nanodots via a seed-mediated growth approach. These nanoparticles and ultralong nanowires showed excellent surface-enhanced Raman scattering (SERS) activity in organic solvents and, therefore, were employed as efficient organic-soluble SERS substrates for the detection of hydrophobic food toxicants, such as 3,4-benzopyrene, and carcinogens, such as benzidine. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Review |
Investigating the Crucial Role of Optic Flow in Postural Control: Central vs. Peripheral Visual Field |
Milena Raffi / Alessandro Piras |
Appl. Sci. 2019, 9(5), 934; |
https://doi.org/10.3390/app9050934 |
Optic flow stimuli are crucial for the control of stance in the upright position. The visual control of posture has recently received a lot of interest from several researchers. One of the most intriguing aspects is the contribution of the different parts of the visual field in the control of stance. Here we reviewed the results of several studies performed with different methodologies that tried to determine the effect of optic flow on postural control, by analyzing the role of the central and peripheral visual fields. Although the results were controversial, the majority of these studies agreed to assign the most important role in postural control to the peripheral retina. However, these studies were performed using different approaches and different definitions of the central and peripheral visual fields. The choice of the exact portion of the retina to be stimulated is crucial given that the stimulation of the central and the peripheral parts of the retina leads to the activation of different geniculo-cortical pathways and results in different cortical processing of information. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Laboratory Observations of Repeated Interactions between Ruptures and the Fault Bend Prior to the Overall Stick-Slip Instability Based on a Digital Image Correlation Method |
Yan-Qun Zhuo / Yanshuang Guo / Sergei Alexandrovich Bornyakov |
Appl. Sci. 2019, 9(5), 933; |
https://doi.org/10.3390/app9050933 |
Fault geometry plays important roles in the evolution of earthquake ruptures. Experimental studies on the spatiotemporal evolution of the ruptures of a fault with geometric bands are important for understanding the effects of the fault bend on the seismogenic process. However, the spatial sampling of the traditional point contact type sensors is quite low, which is unable to observe the detailed spatiotemporal evolution of ruptures. In this study, we use a high-speed camera combined with a digital image correlation (DIC) method to observe ruptures during stick-slip motions of a simulated bent fault. Meanwhile, strain gages were also used to test the results of the DIC method. Multiple cycles of the alternative propagation of ruptures between the two fault segments on the both sides of the fault bend were observed prior to the overall failure of the fault. Moreover, the slip velocity and rupture speed were observed getting higher during this process. These results indicate the repeated interactions between the ruptures and the fault bend prior to the overall instability of the fault, which distinguishes the effect of the fault bend from the effect of asperities in straight faults on the evolution of ruptures. In addition, improvement in the temporal sampling rate of the DIC measurement system may further help to unveil the rupture evolution during the overall instability in future. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Impact of Particle Size Distribution of Colloidal Particles on Contaminant Transport in Porous Media |
Jongmuk Won / Dongseop Lee / Khanh Pham / Hyobum Lee / Hangseok Choi |
Appl. Sci. 2019, 9(5), 932; |
https://doi.org/10.3390/app9050932 |
The presence of retained colloidal particles causes the retardation of contaminant transport when the contaminant is favorably adsorbed to colloidal particles. Although the particle size distribution affects the retention behavior of colloidal particles, the impact of particle size distribution on contaminant transport has not been reported to date. This study investigates the impact of the particle size distribution of the colloidal particles on contaminant transport through numerical simulation by representing the particle size distribution as a lognormal distribution function. In addition, the bed efficiency and contaminant saturation of simulated breakthrough curves were calculated, and a contaminant transport model with the Langmuir isotherm for the reaction between the contaminant–sand and contaminant–colloidal particle was introduced and validated with experimental data. The simulated breakthrough curves, bed efficiency, and contaminant saturation indicated that an increase in the mean and standard deviation of the particle size distribution causes the retardation of contaminant transport. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
A Comprehensive Feature Comparison Study of Open-Source Container Orchestration Frameworks |
Eddy Truyen / Dimitri Van Landuyt / Davy Preuveneers / Bert Lagaisse / Wouter Joosen |
Appl. Sci. 2019, 9(5), 931; |
https://doi.org/10.3390/app9050931 |
(1) Background: Container orchestration frameworks provide support for management of complex distributed applications. Different frameworks have emerged only recently, and they have been in constant evolution as new features are being introduced. This reality makes it difficult for practitioners and researchers to maintain a clear view of the technology space. (2) Methods: we present a descriptive feature comparison study of the three most prominent orchestration frameworks: Docker Swarm, Kubernetes, and Mesos, which can be combined with Marathon, Aurora or DC/OS. This study aims at (i) identifying the common and unique features of all frameworks, (ii) comparing these frameworks qualitatively and quantitatively with respect to genericity in terms of supported features, and (iii) investigating the maturity and stability of the frameworks as well as the pioneering nature of each framework by studying the historical evolution of the frameworks on GitHub. (3) Results: (i) we have identified 124 common features and 54 unique features that we divided into a taxonomy of 9 functional aspects and 27 functional sub-aspects. (ii) Kubernetes supports the highest number of accumulated common and unique features for all 9 functional aspects; however, no evidence has been found for significant differences in genericity with Docker Swarm and DC/OS. (iii) Very little feature deprecations have been found and 15 out of 27 sub-aspects have been identified as mature and stable. These are pioneered in descending order by Kubernetes, Mesos, and Marathon. (4) Conclusion: there is a broad and mature foundation that underpins all container orchestration frameworks. Likely areas for further evolution and innovation include system support for improved cluster security and container security, performance isolation of GPU, disk and network resources, and network plugin architectures. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Wet Snow Flashover Characteristics of 500-kV AC Insulator Strings with Different Arrangements |
Jingwei Xu / Fanghui Yin / Longji Li / Qingfeng Wen / Hao Wang / Shunnan Liu / Zhidong Jia / Masoud Farzaneh |
Appl. Sci. 2019, 9(5), 930; |
https://doi.org/10.3390/app9050930 |
In order to study the wet snow flashover characteristics of 500-kV AC insulator strings under different arrangements, wet snow flashover tests were carried out in the large climate chamber of China Electric Power Research Institute (CEPRI). The wet snow flashover voltages were obtained by the even-rising method and the flashovers were filmed by a camera. The test results showed that the installation of an anti-icing shed of large diameter could increase the wet snow flashover voltage. The distance between the two insulators was a key parameter that influenced the discharge process and the flashover voltage. Under Λ-string arrangement, for common insulators, the flashover performance of iced insulators increased with the connection angle; for anti-icing insulators, the flashover performance increased at first and then decreased with the connection angle. In wet snow conditions, when the connection angle was at the commonly adopted angle of 60°, the flashover performance of the common insulators under the V-string and Λ-string arrangements was almost the same. For anti-icing insulators, however, the V-string arrangement was recommended according to the tests. The results obtained in this study can provide a reference for external insulation design in wet snow conditions. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
The Virial Effect—Applications for SF6 and CH4 Thermal Plasmas |
Andriniaina Harry Solo / Pierre Freton / Jean-Jacques Gonzalez |
Appl. Sci. 2019, 9(5), 929; |
https://doi.org/10.3390/app9050929 |
A tool based on the mass action law was developed to calculate plasma compositions and thermodynamic properties for pure gases and mixtures, assuming a local thermodynamic equilibrium for pressures of up to 300 bar. The collection of the data that was necessary for tool calculation was automated by another tool that was written using Python, and the formats for the model were adapted directly from the NIST and JANAF websites. In order to calculate the plasma compositions for high pressures, virial correction was introduced. The influences of the parameters that were chosen to calculate the Lennard–Jones (12-6) potential were studied. The results at high pressure show the importance of virial correction for low temperatures and the dependence of the dataset used. Experimental data are necessary to determine a good dataset, and to obtain interaction potential. However, the data available in the literature were not always provided, so they are not well-adapted to a large pressure range. Due to this lack, the formulation provided by L. I. Stiel and G. Thodos (Journal of Chemical and Engineering Data, vol. 7, 1962, p. 234–236) is a good alternative when the considered pressure is not close to the critical point. The results may depend strongly on the system studied: examples using SF6 and CH4 plasma compositions are given at high pressure. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Robust Planning of Energy and Environment Systems through Introducing Traffic Sector with Cost Minimization and Emissions Abatement under Multiple Uncertainties |
Cong Chen / Xueting Zeng / Guohe Huang / Lei Yu / Yongping Li |
Appl. Sci. 2019, 9(5), 928; |
https://doi.org/10.3390/app9050928 |
Motor vehicles have been identified as a growing contributor to air pollution, such that analyzing the traffic policies on energy and environment systems (EES) has become a main concern for governments. This study developed a dual robust stochastic fuzzy optimization—energy and environmental systems (DRSFO-EES) model for sustainable planning EES, while considering the traffic sector through integrating two-stage stochastic programming, robust two-stage stochastic optimization, fuzzy possibilistic programming, and robust fuzzy possibilistic programming methods into a framework, which can be used to effectively tackle fuzzy and stochastic uncertainties as well as their combinations, capture the associated risks from fuzzy and stochastic uncertainties, and thoroughly analyze the trade-offs between system costs and reliability. The proposed model can: (i) generate robust optimized solutions for energy allocation, coking processing, oil refining, heat processing, electricity generation, electricity power expansion, electricity importation, energy production, as well as emission mitigation under multiple uncertainties; (ii) explore the impacts of different vehicle policies on vehicular emission mitigation; (iii) identify the study of regional atmospheric pollution contributions of different energy activities. The proposed DRSFO-EES model was applied to the EES of the Beijing-Tianjin-Hebei (BTH) region in China. Results generated from the proposed model disclose that: (i) limitation of the number of light-duty passenger vehicles and heavy-duty trucks can effectively reduce vehicular emissions; (ii) an electric cars’ policy is enhanced by increasing the ratio of its power generated from renewable sources; and (iii) the air-pollutant emissions in the BTH region are expected to peak around 2030, because the energy mix of the study region would be transformed from one dominated by coal to one with a cleaner pattern. The DRSFO-EES model can not only provide scientific support for the sustainable managing of EES by cost-effective ways, but also analyze the desired policies for mitigating pollutant emissions impacts with a risk adverse attitude under multiple uncertainties. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Application of Sliding Rehabilitation Machine in Patients with Severe Cognitive Dysfunction after Stroke |
Ae Ryoung Kim / Yang-Soo Lee |
Appl. Sci. 2019, 9(5), 927; |
https://doi.org/10.3390/app9050927 |
A sliding rehabilitation machine (SRM) allows closed kinetic chain exercises of the hip, knee, and ankle. This study aimed to explore the feasibility of SRM training when included in an intensive rehabilitation program for post-stroke patients with severe cognitive dysfunction. The study design is a retrospective analysis. Patients who were admitted for inpatient rehabilitation after stroke with subsequent severe cognitive dysfunction were enrolled. Training with the SRM was conducted twice a day from Monday to Friday during hospitalization for three to four weeks. The number of sessions and the occurrence of side effects were documented daily. The SRM’s inclination angle, Berg Balance Scale (BBS), manual muscle test (MMT), and Korean version of the Modified Barthel Index (K-MBI) were documented upon admission and discharge. In 30 patients, 1736 sessions were performed from a total of 1754 scheduled sessions of SRM training. The performance rate was 98.9%, and there were no serious side effects. Transient side effects such as dizziness, nausea, and knee pain were observed in a few cases. At discharge, patients showed improvement in the SRM inclination angle, BBS, MMT, and K-MBI. This study shows that the use of the SRM for intensive muscle strengthening is readily applicable to patients who have had a stroke with severe cognitive dysfunction. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
A Transferable Prediction Approach for the Remaining Useful Life of Lithium-Ion Batteries Based on Small Samples |
Haochen Qin / Xuexin Fan / Yaxiang Fan / Ruitian Wang / Qianyi Shang / Dong Zhang |
Appl. Sci. 2023, 13(14), 8498; |
https://doi.org/10.3390/app13148498 |
Predicting the remaining useful life (RUL) of batteries can help users optimize battery management strategies for better usage planning. However, the RUL prediction accuracy of lithium-ion batteries will face challenges due to fewer data samples available for the new type of battery. This paper proposed a transferable prediction approach for the RUL of lithium-ion batteries based on small samples to reduce time in preparing battery aging data and improve prediction accuracy. This approach, based on improvements from the adaptive boosting algorithm, is called regression tree transfer adaptive boosting (RT-TrAdaBoost). It combines the advantages of ensemble learning and transfer learning and achieves high computational efficiency. The RT-TrAdaBoost approach takes the charging voltage and temperature curve as input and utilizes the classification and regression tree (CART) as the base learner, which has better feature capture ability. In the experiment, the working condition migration experiment and battery type migration experiment are conducted on non-overlapping datasets. The verified results revealed that the RT-TrAdaBoost approach could transfer not only the battery aging knowledge between various working conditions but also realize the RUL migration prediction from lithium iron phosphate battery to lithium cobalt oxide battery. The analysis of error and computation time demonstrates the proposed method’s high efficiency and speed. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Research on Multi-Sensor Simultaneous Localization and Mapping Technology for Complex Environment of Construction Machinery |
Haoling Ren / Yaping Zhao / Tianliang Lin / Jiangdong Wu |
Appl. Sci. 2023, 13(14), 8496; |
https://doi.org/10.3390/app13148496 |
Simultaneous localization and mapping (SLAM), as a key task of unmanned vehicles for construction machinery, is of great significance for later path planning and control. Construction tasks in the engineering field are mostly carried out in bridges, tunnels, open fields, etc. The prominent features of these environments are high scene similarity, few geometric features, and large-scale repetitive texture information, which is prone to sensor detection degradation. This leads to positioning drift and map building failure. The traditional method of motion estimation and 3D reconstruction uses a single sensor, which lacks enough information, has poor adaptability to the environment, and cannot guarantee good positioning accuracy and robustness in complex environments. Currently, the strategy of multi-sensor fusion is proven to be an effective solution and is widely studied. This paper proposes a SLAM framework that integrates LiDAR, IMU, and camera. It tightly couples the texture information observed by camera, the geometric information scanned by LiDAR, and the measured value of IMU, allowing visual-inertial odometry (VIO) and LiDAR-inertial odometry (LIO) common implementation. The LIO subsystem extracts point cloud features and matches them with the global map. The obtained pose estimation can be used for the initialization of the VIO subsystem. The VIO system uses direct method to minimize the photometric error and IMU measurement error between images to estimate the pose of the robot and the geometric structure of the scene. The two subsystems assist each other to perform pose estimation, and can operate normally even when any subsystem fails. A factor graph is used to combine all constraints to achieve global pose optimization. Keyframe and sliding window strategies are used to ensure real-time performance. Through real-vehicle testing, the system can perform incremental and real-time state estimation and reconstruct a dense 3D point cloud map, which can effectively solve the problems of positioning drift and mapping failure in the lack of geometric features or challenging construction environments. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Communication |
Real-Time Information Fusion System Implementation Based on ARM-Based FPGA |
Yu-Hsiang Tsai / Yung-Jhe Yan / Meng-Hsin Hsiao / Tzu-Yi Yu / Mang Ou-Yang |
Appl. Sci. 2023, 13(14), 8497; |
https://doi.org/10.3390/app13148497 |
In this study, an information fusion system displayed fusion information on a transparent display by considering the relationships among the display, background exhibit, and user’s gaze direction. We used an ARM-based field-programmable gate array (FPGA) to perform virtual–real fusion of this system as well as evaluated the virtual–real fusion execution speed. The ARM-based FPGA used Intel® RealsenseTM D435i depth cameras to capture depth and color images of an observer and exhibit. The image data was received by the ARM side and fed to the FPGA side for real-time object detection. The FPGA accelerated the computation of the convolution neural networks to recognize observers and exhibits. In addition, a module performed by the FPGA was developed for rapid registration between the color and depth images. The module calculated the size and position of the information displayed on a transparent display according to the pixel coordinates and depth values of the human eye and exhibit. A personal computer with GPU RTX2060 performed information fusion in ~47 ms, whereas the ARM-based FPGA accomplished it in 25 ms. Thus, the fusion speed of the ARM-based FPGA was 1.8 times faster than on the computer. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Two Revised Deep Neural Networks and Their Applications in Quantitative Analysis Based on Near-Infrared Spectroscopy |
Hong-Hua Huang / Jian-Fei Luo / Feng Gan / Philip K. Hopke |
Appl. Sci. 2023, 13(14), 8494; |
https://doi.org/10.3390/app13148494 |
Small data sets make developing calibration models using deep neural networks difficult because it is easy to overfit the system. We developed two deep neural network architectures by revising two existing network architectures: the U-Net and the attention mechanism. The major changes were to use 1D convolutional layers to replace the fully connected layers. We also designed and combined average pooling and maximum pooling in our revised networks, respectively. We applied these revised network architectures to three publicly available data sets and the resulting calibration models can generate acceptable results for general quantitative analysis. It also generated rather good results for data sets that concern calibration transfer. It demonstrates that constructing network architectures by properly revising existing successful network architectures may provide additional choices in the exploration of the application of deep neural network in analytical chemistry. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Semisupervised Speech Data Extraction from Basque Parliament Sessions and Validation on Fully Bilingual Basque–Spanish ASR |
Mikel Penagarikano / Amparo Varona / Germán Bordel / Luis Javier Rodriguez-Fuentes |
Appl. Sci. 2023, 13(14), 8492; |
https://doi.org/10.3390/app13148492 |
In this paper, a semisupervised speech data extraction method is presented and applied to create a new dataset designed for the development of fully bilingual Automatic Speech Recognition (ASR) systems for Basque and Spanish. The dataset is drawn from an extensive collection of Basque Parliament plenary sessions containing frequent code switchings. Since session minutes are not exact, only the most reliable speech segments are kept for training. To that end, we use phonetic similarity scores between nominal and recognized phone sequences. The process starts with baseline acoustic models trained on generic out-of-domain data, then iteratively updates the models with the extracted data and applies the updated models to refine the training dataset until the observed improvement between two iterations becomes small enough. A development dataset, involving five plenary sessions not used for training, has been manually audited for tuning and evaluation purposes. Cross-validation experiments (with 20 random partitions) have been carried out on the development dataset, using the baseline and the iteratively updated models. On average, Word Error Rate (WER) reduces from 16.57% (baseline) to 4.41% (first iteration) and further to 4.02% (second iteration), which corresponds to relative WER reductions of 73.4% and 8.8%, respectively. When considering only Basque segments, WER reduces on average from 16.57% (baseline) to 5.51% (first iteration) and further to 5.13% (second iteration), which corresponds to relative WER reductions of 66.7% and 6.9%, respectively. As a result of this work, a new bilingual Basque–Spanish resource has been produced based on Basque Parliament sessions, including 998 h of training data (audio segments + transcriptions), a development set (17 h long) designed for tuning and evaluation under a cross-validation scheme and a fully bilingual trigram language model. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
FPGA-Based Methodology for Detecting Positional Accuracy Degradation in Industrial Robots |
Ervin Galan-Uribe / Luis Morales-Velazquez / Roque Alfredo Osornio-Rios |
Appl. Sci. 2023, 13(14), 8493; |
https://doi.org/10.3390/app13148493 |
Industrial processes involving manipulator robots require accurate positioning and orienting for high-quality results. Any decrease in positional accuracy can result in resource wastage. Machine learning methodologies have been proposed to analyze failures and wear in electronic and mechanical components, affecting positional accuracy. These methods are typically implemented in software for offline analysis. In this regard, this work proposes a methodology for detecting a positional deviation in the robot’s joints and its implementation in a digital system of proprietary design based on a field-programmable gate array (FPGA) equipped with several developed intellectual property cores (IPcores). The method implemented in FPGA consists of the analysis of current signals from a UR5 robot using discrete wavelet transform (DWT), statistical indicators, and a neural network classifier. IPcores are developed and tested with synthetic current signals, and their effectiveness is validated using a real robot dataset. The results show that the system can classify the synthetic robot signals for joints two and three with 97% accuracy and the real robot signals for joints five and six with 100% accuracy. This system aims to be a high-speed reconfigurable tool to help detect robot precision degradation and implement timely maintenance strategies. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Spectra Prediction for WLEDs with High TLCI |
Haiyang Wang / Peipei Wang / Zhiliang Jin / Yang Song / Daxi Xiong |
Appl. Sci. 2023, 13(14), 8487; |
https://doi.org/10.3390/app13148487 |
White light-emitting diodes (WLEDs) with a high television lighting consistency index (TLCI) are becoming popular in stadium, studio, and stage lighting, but they are hard to empirically manufacture because they exploit the response of a camera rather than that of the human eye. In this study, blue chips with green and red phosphors were used to build high-TLCI WLEDs, and a spectral prediction model for WLEDs used for calculating the TLCI was established. The model considers the reabsorption and re-emission of phosphors and spectral shift. To validate the model, WLEDs with a TLCI greater than 90, from 3000 K to 7000 K, were predicted and packaged. The maximum difference in the TLCI between the measured and predicted model values is approximately 1.93%. The spectral prediction model proposed in this study is expected to provide a helpful guideline for building high-TLCI WLEDs. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Optimization of Growth Conditions for Magnetospirillum magnetotacticum and Green Synthesis of Metallic Nanoparticles |
Rebekah Eleasa Sancho / Anushka Govindsamy / Karen Pillay |
Appl. Sci. 2023, 13(14), 8491; |
https://doi.org/10.3390/app13148491 |
Nanotechnology is especially useful in biotechnological and biomedical applications as nanomaterials have unique physicochemical properties. Current physical and chemical techniques used for the production of nanoparticles have various disadvantages that has led to the evaluation of biological strategies. This study focused on the use of a bacterial species known as Magnetospirillum magnetotacticum for the production of metallic nanoparticles. The cultivation of MTB is known to be tedious and time-consuming using the current standardized magnetic spirillum growth media (MSGM). This study explored the optimization of MSGM for improved growth and nanoparticle yield. It was found that glucose significantly improved and sustained the growth of M. magnetotacticum compared to other sole carbon sources having a sustainable OD of ~1.15. However, use of a higher concentration of sodium nitrate (40 mM) as a nitrogen source was able to significantly improve iron-containing nanoparticle yield by 1.6× with a final yield of 22 mg/50 mL when compared to the yield obtained from the MSGM original media. Growth media with a combination of glucose, sodium nitrate, ammonium sulphate and yeast extract showed the highest exponential growth of Magnetospirillum magnetotacticum compared to all other MSGM modifications with the highest OD being 1.7. Silver and gold nanoparticles were also successfully produced in addition to iron-containing nanoparticles. Overall, no direct correlation between growth and nanoparticle yield was found. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Investigation on the Stress and Deformation Evolution Laws of Shield Tunnelling through a Mining Tunnel Structure |
Entong Du / Lei Zhou / Ruizhen Fei |
Appl. Sci. 2023, 13(14), 8489; |
https://doi.org/10.3390/app13148489 |
In the construction of a shield crossing an existing mined tunnel without load, it is imperative to develop corresponding design standards that reflect actual engineering force characteristics to ensure the successful completion of the tunnel construction. This study uses the MIDAS-GTS NX 2022 finite element software to facilitate the creation of a numerical model of a shield structure for an air-push-over mine tunnel project in Changsha, China while investigating the stress field’s evolution during shield construction and calculating the maximum positive and negative bending moments and maximum axial forces for different structures and other force states under various construction conditions. This study’s findings informed the design and construction optimisation of a shield tunnelling empty-push method. The outcomes of this numerical simulation led to several key findings: (1) The soil density exerted a significantly greater impact on the internal forces of the initial support structure than both the tunnel depth and soil Poisson’s ratio. Additionally, a sudden shift in internal forces occurred within the 300–350 mm range when the lining thickness was altered. (2) Factors such as the tunnel depth, soil density, soil Poisson’s ratio μ, and lining thickness similarly influenced the internal forces of the segment and the initial support. Notably, the backfill layer thickness significantly affected the segment’s maximum axial force, causing an abrupt change of approximately 300 mm. (3) It is essential to control the guide rail’s thickness under the shield machine equipment’s weight constraint to prevent it from becoming overly large. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Exploring the Effects of Low-Level Laser Therapy on the Cytocompatibility and Osteo/Odontogenic Potential of Gingival-Derived Mesenchymal Stem Cells: Preliminary Report |
Yaser A. Alhazmi / Mohammed Y. Aljabri / Shereen N. Raafat / Shaimaa M. Gomaa / Mohamed Shamel |
Appl. Sci. 2023, 13(14), 8490; |
https://doi.org/10.3390/app13148490 |
Numerous tissue engineering uses for gingival-derived mesenchymal stem cells (GMSCs) have been demonstrated. Recently, low-level laser therapy (LLLT) has been projected as a factor that can improve MSCs’ regeneration capacity. Therefore, the aim of this research was to examine the impact of LLLT at 1.5 J/cm2 and 3 J/cm2 on the viability and osteo/odontogenic potential of GMSCs. An MTT assay was performed to detect viability. Osteo/odontogenic differentiation was evaluated using Alizarin Red S staining and qRT-PCR for the evaluation of the RUNX2, OC, DMP1, and DSPP genes. A two-way ANOVA with Tukey’s post hoc test was used to determine the statistical significance between groups. The results revealed that LLLT of both energy densities had no cytotoxic effect on GMSC viability. LLLT of 1.5 J/cm2 demonstrated better viability than the higher energy density (3 J/cm2). Furthermore, the osteo/odontogenic differentiation potential was promoted following LLLT radiation, where both groups exhibited mineralized nodule formation, with the low-energy laser having a significantly higher Alizarin Red S stain level. A qRT-PCR analysis revealed higher expression levels of osteogenic and odontogenic markers in the LLLT groups compared to the control group. In conclusion, this study showed the potential application of LLLT as a non-toxic and effective strategy to enhance the regenerative capacity of GMSCs for tissue engineering and clinical treatments in the oral and craniofacial fields. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
A Perfect Decomposition Model for Analyzing Transportation Energy Consumption in China |
Yujie Yuan / Xiushan Jiang / Chun Sing Lai |
Appl. Sci. 2023, 13(7), 4179; |
https://doi.org/10.3390/app13074179 |
Energy consumption in transportation industry is increasing. Transportation has become one of the fastest energy consumption industries. Transportation energy consumption variation and the main influencing factors of decomposition contribute to reduce transportation energy consumption and realize the sustainable development of transportation industry. This paper puts forwards an improved decomposition model according to the factors of change direction on the basis of the existing index decomposition methods. Transportation energy consumption influencing factors are quantitatively decomposed according to the transportation energy consumption decomposition model. The contribution of transportation turnover, transportation structure and transportation energy consumption intensity changes to transportation energy consumption variation is quantitatively calculated. Results show that there exists great energy-conservation potential about transportation structure adjustment, and transportation energy intensity is the main factor of energy conservation. The research achievements enrich the relevant theory of transportation energy consumption, and help to make the transportation energy development planning and carry out related policies. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Editorial |
Applied Agri-Technologies for Agriculture 4.0—Part I |
Dimitrios Kateris / Dionysis Bochtis |
Appl. Sci. 2023, 13(7), 4180; |
https://doi.org/10.3390/app13074180 |
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| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Using Historical Data to Dynamically Route Post-Disaster Assessment Unmanned Aerial Vehicles in the Context of Responding to Tornadoes |
Sean Grogan / Michel Gamache / Robert Pellerin |
Appl. Sci. 2023, 13(7), 4178; |
https://doi.org/10.3390/app13074178 |
Responding to tornado disasters resides at a unique intersection of search and rescue operations: it has attributes of wilderness and maritime search and rescue operations and search and rescue operations in the aftermath of earthquakes and hurricanes. This paper presents a method of attempting to leverage historical data to more efficiently identify the extent of the area damaged by a tornado. To assist in building and understanding the historical data, we also develop a method to generate tornado areas that react similarly to the limited historical data set. The paper successfully demonstrates the method of creating artificial tornado instances that can be used as a testing sandbox for the further development of tools when responding to tornado-type disasters. These artificial instances perform similarly in some important metrics to the historical database of tornado instances that we produced. This paper also shows that the use of historical tornado trends has an impact on the response method outlined in this article, typically reducing the standard deviation of the time it takes to fully identify the extent of the damage. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Morphological Integration on the Calcaneum of Domestic Sheep (Ovis aries Linnaeus, 1758)—A Geometric Morphometric Study |
Pere Miquel Parés-Casanova / Carme Rissech / Simon Davis / Lluís Lloveras |
Appl. Sci. 2023, 13(7), 4177; |
https://doi.org/10.3390/app13074177 |
Morphological integration and modularity refer to the degree of covariation between the different components of an anatomical structure. Modularity refers to structures that have components which covary strongly, but at the same time are relatively independent. Integration refers to the coordinated variation of the components of a functional anatomical structure. The hindlimb basipodium is a complex functional structure. The integration of its parts must arise from a coordinated development and functionality. Our objective in this study was to study the levels of integration of two modules on the calcaneum in domestic sheep. The calcaneum develops from two different centres. One gives rise to the body and its process while the other gives rise to the distal half of the bone. The hypothesis of modularity of two parts of the calcaneum was tested using the Escoufier RV coefficient and an analysis of two blocks of Partial Least Squares. These allowed us to evaluate the level of morphological integration. For this purpose, digital images of the medial aspect of complete calcanea of 47 domestic sheep (Ovis aries) were used. Twenty 2D coordinates of homologous anatomical landmarks (4 for the body and the process and 16 for the distal half of the bone) were collected as morphometric data. These were studied using geometric morphometrics. The results indicated good evidence of modular organization and a medium morphological integration between the two modules. Thus, according to our results, the two modules seem to exist and behave in a rather independent way. They appear to share functions rather than precursors of development. This study is important in order to elucidate the underlying factors in the processes of the development of the sheep calcaneum. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Analytical Method and Analysis of Cold-Joint Interface |
Juozas Mas??nas / Remigijus ??alna / Linas Juknevi??ius / Juozas Valivonis |
Appl. Sci. 2023, 13(7), 4176; |
https://doi.org/10.3390/app13074176 |
The behaviour of the interface between two concrete layers, subjected to shear, is a complex process that is influenced by many different parameters. Knowledge of concrete interface performance is insufficient to this day. Most of the existing analytical methods are only suitable for determining the highest interface shear resistance and do not consider the interface behaviour at other stages. This article focuses on smooth concrete interfaces, which have their layers cast at different times (cold-joint interface). By analysing the results of different experimental push-off tests, presented in the literature, a novel analytical method was developed for the previously described concrete interface. Furthermore, numerical models of push-off tests were developed. A parametric numerical analysis was employed to determine the influence of various physical parameters that might affect interface shear behaviour. Most importantly, the results acquired using the proposed analytical method were compared with the findings of numerical analysis and experimental results acquired by other authors. The values of shear stress and slippage were found to be relatively close. Therefore, the proposed analytical method is suitable for the analysis of smooth concrete interfaces cast at different times. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Device Orientation Independent Human Activity Recognition Model for Patient Monitoring Based on Triaxial Acceleration |
Sara Caramaschi / Gabriele B. Papini / Enrico G. Caiani |
Appl. Sci. 2023, 13(7), 4175; |
https://doi.org/10.3390/app13074175 |
Tracking a person’s activities is relevant in a variety of contexts, from health and group-specific assessments, such as elderly care, to fitness tracking and human–computer interaction. In a clinical context, sensor-based activity tracking could help monitor patients’ progress or deterioration during their hospitalization time. However, during routine hospital care, devices could face displacements in their position and orientation caused by incorrect device application, patients’ physical peculiarities, or patients’ day-to-day free movement. These aspects can significantly reduce algorithms’ performances. In this work, we investigated how shifts in orientation could impact Human Activity Recognition (HAR) classification. To reach this purpose, we propose an HAR model based on a single three-axis accelerometer that can be located anywhere on the participant’s trunk, capable of recognizing activities from multiple movement patterns, and, thanks to data augmentation, can deal with device displacement. Developed models were trained and validated using acceleration measurements acquired in fifteen participants, and tested on twenty-four participants, of which twenty were from a different study protocol for external validation. The obtained results highlight the impact of changes in device orientation on a HAR algorithm and the potential of simple wearable sensor data augmentation for tackling this challenge. When applying small rotations (<20 degrees), the error of the baseline non-augmented model steeply increased. On the contrary, even when considering rotations ranging from 0 to 180 along the frontal axis, our model reached a f1-score of 0.85±0.11 against a baseline model f1-score equal to 0.49±0.12. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
A Method for Managing Software Assets in the Automotive Industry (Focusing on the Case of Hyundai Motor Company and Parts Makers) |
Changhan Ryu / Sungryong Do |
Appl. Sci. 2023, 13(7), 4174; |
https://doi.org/10.3390/app13074174 |
We propose a method for managing software assets in the automotive industry to enhance software competitiveness and to reduce development costs. The ownership of software assets in the automotive industry is held by automotive parts companies, making it challenging to exchange these technologies. Moreover, the criteria for determining software assets are often unclear, resulting in difficulties in integrating automotive software and implementing over-the-air updates. To address these issues, we suggest breaking down black-boxed software assets into tradable components, valuating them, and introducing the concept of exchanging software technology assets. Additionally, we provide a structured approach for recycling used software assets and establish a software asset management system for registration and tracking. Our proposed approach can help traditional automotive OEMs narrow the technology gap with automakers such as Tesla and improve their software competitiveness in the automotive industry. This paper contributes to the advancement of software asset management practices in the automotive industry, and provides insights into the integration of automotive software and over-the-air updates. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
A Non-Destructive Method for Predicting Critical Load, Critical Thickness and Service Life for Corroded Spherical Shells under Uniform External Pressure Based on NDT Data |
Cheng Huijuan Liu / Giuseppe Lacidogna |
Appl. Sci. 2023, 13(7), 4172; |
https://doi.org/10.3390/app13074172 |
A pressurized spherical shell that is continuously corroded will likely buckle and lose its stability. There are many analytical and numerical methods to study this problem (critical load, critical thickness, and service life), but the friendliness (operability) in engineering test applications is still not ideal. Therefore, in this paper, we propose a new non-destructive method by combining the Southwell non-destructive procedure with the stable analysis method of corroded spherical thin shells. When used carefully, it can estimate the critical load (critical thickness) and service life of these thin shells. Furthermore, its procedure proved to be more practical than existing methods; it can be easily mastered, applied, and generalized in most engineering tests. When used properly, its accuracy is acceptable in the field of engineering estimations. In the context of the high demand for non-destructive analysis in industry, it may be of sufficient potential value to be used as a reference for existing estimating methods based on NDT data. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
System Architecture Design of IoT-Based Smart Cities |
Bedir Tekinerdogan / ??mer K??ksal / Turgay ??elik |
Appl. Sci. 2023, 13(7), 4173; |
https://doi.org/10.3390/app13074173 |
The integration of Internet of Things (IoT) networks into smart cities is crucial to enhance the efficiency of city operations and services. Designing a smart city architecture that can adapt to the constantly changing functional and quality requirements of city services is essential. However, critical decisions must be made during this process, such as selecting communication protocols, ensuring security and safety, optimizing time performance, and processing data capacity. To address these challenges, this paper proposes a systematic approach to guide the system architecture design of IoT-based smart cities. The approach starts with feature-driven domain analysis to model smart city requirements, followed by the design of a reference architecture for IoT-based smart cities. The architecture is modeled using selected architectural views, while considering key stakeholders and their concerns. Additionally, this paper presents valuable insights into lessons learned and challenges encountered during the process of creating IoT-based smart cities. This information can assist practitioners in developing such smart cities and pave the way for future research in this field. By following this proposed approach, smart city architects can design a robust and adaptable system architecture that can meet the evolving needs of smart city services. |
| 29 |
Applied Sciences |
v.13(14), Jul 2023 |
Article |
Possibilities of Detecting Damage Due to Osmosis of GFRP Composites Used in Marine Applications |
Waldemar Swiderski / Martyna Strag |
Appl. Sci. 2023, 13(7), 4171; |
https://doi.org/10.3390/app13074171 |
The marine composites market is driven by the increasing demand for lightweight, corrosion-resistant, and impact-resistant boats. Polymer matrix composites are currently the most popular composite material in marine applications. Fiberglass composites are practically the main type of fiber composites that are used extensively in marine applications. Due to the aggressive sea environment, composite structural elements of ships are exposed to damage due to the phenomenon of osmosis. This damage is also favored by defects that result from impacts and technological errors during the production of these elements. Non-destructive testing methods are necessary to detect damage in the internal structure of the composite. The paper presents a numerical analysis of the possibility of using vibrothermography in the detection of defects in glass–fiber reinforced laminates in marine applications. Numerical simulations have shown that the most favorable method for detecting defects will be acoustic waves. This is an unusual application because, as a rule, the range of ultrasonic waves is used in vibrothermography. In our further works, it is planned to verify numerical calculations through experimental research. The applicability of the terahertz technique was also assessed. During the experimental testing, all defects in the test sample of the glass–fiber reinforced composite were detected using this technique. The presented results indicate the applicability of the presented methods for the detection of |
