esa-sceva/satcom-chunk-collection huggingface dataset:
# ChatGPT in Education: A Systematic Review on Opportunities, Challenges, and Future Directions
## 7 Key Findings and Implications
### Summary of Research Questions  
As illustrated in Table 7, the following research questions were addressed: (1) How has ChatGPT been applied in education? The findings show that ChatGPT is utilized for personalized learning, tutoring, and content creation. However, its application lacks real-world validation [31, 51]. (2) What are the major governance and policy challenges? The findings show that major challenges include ethical concerns, academic dishonesty, AI bias, data privacy issues, and increased teacher workload [45]. (3) What future research directions are needed? The findings show there is a need for regulatory frameworks, AI literacy programs, and empirical validation of AI in education [39].  
Based on the findings across 40 peer-reviewed studies, it is evident that ChatGPT integration in education yields both pedagogical opportunities and ethical concerns. For example, studies such as [1, 7] illustrate enhanced student engagement and personalized learning pathways due to ChatGPT's adaptability. However, others like [5, 6] emphasize the growing risks of academic dishonesty and over-reliance on AI. Synthesizing these perspectives reveals a dual reality: while AI-driven tools like ChatGPT can transform educational delivery, their integration must be accompanied by clear ethical guidelines and adaptive teaching strategies. Unlike earlier studies that focused narrowly on either opportunity or risk, this review bridges both to propose a balanced framework for future implementation.
# A Novel Hybrid Method for Urban Green Space Segmentation from High-Resolution Remote Sensing Images
## 2 Materials and Methods  
This paper combines HRS image band information and the vegetation index to propose a DL method (MAFANet) based on encoding and decoding structure. This method uses attention aggregation and bilateral feature fusion to realize the utilization of multi-scale information and can effectively segment green areas. Figure 1 shows the overall structure of MAFANet, which consists of the ResNet50, MSPA, BFF, and DE modules.
# A New Signal Processing Method for Time-of-Flight and Center Frequency Estimation
###### Abstract
In one paper [19], the continuous wavelet transform based on the scale-averaged power (SAP) and the discrete stationary wavelet transform (DSWT) were used. Studies have shown that both methods produce low error for non-overlapping signals and acceptable error for partially overlapping signals. One work [20] describes the broadband wavelet method for time-of-flight measurements of ultrasound pulse echoes. A paper [21] presents the application of the wavelet transform integrated with a threshold detection method. However, the application of most of these methods becomes problematic when the background noise is high and the signal is variable. In this article, we propose an algorithm for determining the propagation time and center frequency of signals based on the use of zero-crossing times of filtered signals to calculate these parameters. Section 2 describes the methodology used to determine the time-of-flight and center frequency. The processing of different experimental signals by the proposed method is described in Section 3. Section 4 discusses the results of using the method and the limitations of this method.
# Continuous-Wave THz Imaging for Biomedical Samples
## 5 The Application of CW Imaging with Biological Tissues
### Tumour Tissues  
When the THz beam passes through the network structure of the water molecules, the hydrogen bonds of water oscillate and excite resonance, and the dipole direction of the water molecules rotates and relaxes to form a new network structure of water molecules. Many interactions are formed between water molecules in picosecond time, so the absorption of THz radiation by water molecules is very strong [75]. Most biological tissues have high water content and strong absorption characteristics for THz radiation, depending on the tissues type and THz frequency. THz detection technology is limited to the surface features of the tissues because the depth of THz radiation penetrating tissues is limited to hundreds or even tens of microns, and the reflective measurement is more suitable for measuring hydrated ex vivo tissues compared with transmissive detection. Many in and ex vivo tissues can be THz imaged by utilising the strong interaction between THz radiation and water, such as fibrous connective tissues of the breast with about 60-75% water content [76], which have a high refractive index and absorption coefficient in the THz frequency range. [PERSON] et al. imaged a fresh mouse brain tumour and the same tissue completely dehydrated, and they found that the refractive index and absorption coefficient of the dehydrated brain tumour diminished [77]. In recent years, many optimised methods such as paraffin embedding [78], tissue freezing [79], and glycerol [80] have been proposed to enhance the penetration depth of THz radiation with biological samples.
## 2 Materials and Methods
### Testing Model's Performance on New Data  
Before testing our model, it would be a good strategy to perform the fine-tuning of hyperparameters using GridsearchCV [36]. However, fine-tuning could sometimes lead to poor performance or in our case false predictions, as already happened in our initial model. The specific problems that were identified in the initial model using fine-tuning are as follows:  
* Hyperparameters over-tuned to the validation set, especially in cases when the validation set is small, leading to false predictions on the test set;
* Dimensionality Curse [37]: Using the gridsearch method with many hyperparameters sometimes finds a good combination by chance, rather than through true model improvement;
* Ignored Shifts in Data Distribution [38]: In our case, as the validation set's distribution is different from the test set, fine-tuning may produce biased hyperparameters, causing poor performance on the test set.  
Thus, in this model, fine-tuning was entirely omitted. For model testing, a new set of images was utilized and fed to the best-performing model selected in the previous step.
* Model testing was performed through the classification of an argument between two individuals by using the second half of the images from the folders courtyard_arguing_00 and downtown_arguing_00. The total number of images in this class is 498.
* Casual conversation classification was performed by using images between two individuals casually chatting. The second half of the images from the folders courtyard_warmWelcome_00 and courtyard_giveDirections_00 were used. The total number of the images for this class is also 498.
# Review on Semi-Fragile Watermarking Algorithms for Content Authentication of Digital Images
## 6 Conclusions  
Along with the high-speed development of computer technology and network technology, various kinds of attacks faced by digital images also show the trend of diversification, which poses a serious challenge to the security of digital images. Therefore, the development and improvement of semi-fragile watermarking techniques for image content authentication are still a focus and hotspot in the digital watermarking area. This paper first introduces the basic principle of semi-fragile watermarking technology and the basic characteristics that it needs to meet. Then evaluation indexes, several kinds of attacks, and algorithm performance are analyzed. Finally, depending on whether the tampered areas can be recovered, we classify and review several typical semi-fragile watermarking algorithms, and then summarize and compare various algorithms from different aspects by making four tables.  
Although the research on semi-fragile watermarking algorithms that are used for image content authentication is relatively mature, there are still many difficulties that need to be solved urgently. There is no perfect semi-fragile watermarking algorithm that can meet all the requirements. The existing semi-fragile watermarking algorithm cannot resist all attacks and cannot distinguish all normal image-processing operations from malicious tampering. In addition, many semi-fragile watermarking algorithms are based on image block, which leads to that detection and location for tampered areas are also in block units. This reduces the location accuracy, and it is also not conducive to the recovery of tampered areas. With the introduction of artificial intelligence, semi-fragile watermarking technology has been injected with new vitality. In the future study of semi-fragile watermarks, in addition to solving all above-mentioned difficult problems, researchers will also establish a set of excellent evaluation standards for the watermarking authentication system, making the use of semi-fragile watermarking authentication technology become more extensive in real life.  
This work was supported by the National Natural Science Foundation of China (No. 61702303, No. 61201371), the Natural Science Foundation of Shandong Province, China (No. ZR2017 MF020, No. ZR2015 FP004), and the Research Award Fund for Outstanding Young and Middle-Aged Scientists of Shandong Province, China (No. BS2013 DX022). [PERSON] and [PERSON] reviewed the semi-fragile watermarking algorithms in recent years; [PERSON] and [PERSON] classified the various algorithms, and analyzed the data;  
Figure 3: Image content authentication algorithms based on semi-fragile watermark.  
[PERSON] drafted the manuscript; [PERSON] revised the manuscript. All authors have read and approved the final manuscript.  
The authors declare no conflict of interest.
# Applications of Wireless Sensor Networks: An Up-to-Date Survey
## 2 Main WSN Applications
### Military Applications
#### 2.1.2 Combat Monitoring  
Within a battlefield the firing of guns, mortars artillery, and other weaponry creates sound, heat, and vibrations. This information can be recorded with the use of WSNs and provides an expectation of the location of the enemy. This type of application is described below.  
In [8] the use of acoustic sensor arrays suspended below tethered aerostats to detect and localize moving vehicles, transient signals from mortars, artillery, small arms fire, and locate their source is presented.  
The specific detection system can be used in conjunction with an acoustic vector sensor, to amplify the possibility of locating the threat using the shockwave created by the supersonic bullet and the muzzle blast created by the gun [9].  
Figure 5: Illustration of the system architecture proposed in [6] for target tracking.  
The authors of [10] describe a system consisting of interconnected Body Sensor Networks (BSNs), a sub-family of WSNs, for real-time health monitoring of soldiers. A key component of this system is a BSN that integrates various physiological and biomedical sensors. These sensors are an accelerometer, an EEG simulator, and a SpO\({}_{2}\) sensor, which can be embedded within an advanced combat helmet worn by each soldier. They monitor the various information of health status in real time, such as blood pressure, oxygen saturation, and heart rate. By utilizing the data collected, various methods can be applied in order to train soldiers more efficiently and prepare them more adequately for future engagements.
# Context-Aware Wireless Sensor Networks for Smart Building Energy Management System
## 4 Proposed EMS for SEEB  
The proposed EMS that controls the heaters and implements the efficient energy policy via ICT has three components (Figure 1). First, sensor and actuator modules which are used for environmental sampling and appliance control. Second, a Wireless Sensor Network (WSN) that transmits data and control commands. Third, the software or application which monitors and controls the building appliances, loads, and generators.  
Figure 1: General architecture (**A**) and communication process (**B**) of the proposed Energy Management Systems (EMS).
## 1 Introduction
Through the combination of practice and theory, the theoretical analysis can be confirmed through the existing practice. [PERSON] and [PERSON] [33] and [PERSON] and [PERSON] [34] established a finite element analysis model of 10 cable-stayed bridges with cable layout and girder stiffness as parameters and studied the dynamic and static responses after cable breakage. The results confirm that the DAF of the bridge will change with the stiffness of the girder and the cable layout. [PERSON] et al. [35] used MIDAS/Civil (a finite element program) to establish a three-dimensional simulation model of a double steel arch tower cable-stayed bridge and studied the variation law of main beam line type and cable force after the fracture of different positions and numbers of stay cables. To give a certain forecast result for this special event of broken rope, [PERSON] et al. [36] made a three-dimensional calculation model of a long-span highway-railway cable-stayed bridge. They used a nonlinear implicit dynamic time-history algorithm to study the dynamic response of the whole bridge structure in the case of a sudden cable break, the dynamic response of the bridge structure and the train in the case of train-bridge coupling, and the safety of the bridge. The cable-breaking accident of a cable-stayed bridge may occur not only in the operation stage of the bridge but also in the construction process. [PERSON] et al. [37] studied the formation and distribution of cracks in the concrete main girder after the breakage of multiple cables using field measurement and numerical simulation in view of the successive breakage of nine stay cables on the same side caused by a fire in a construction process. They evaluated the structure of the bridge during the loss and subsequent recovery of the stay cables according to nonlinear numerical research. In general, there is always a balance between calculation accuracy and calculation cost in the simulation of structural damage evolution. By introducing the damage in a reasonable way into the models of different scales, the multiscale analysis method attempts to simulate the failure process of structural damage at a small computational cost. In this paper, the evolution process of corrosion fatigue damage of bridge cable system was simulated and analyzed to better understand the multiscale evolution process of corrosion fatigue damage of cable system and its influence on the whole structure of the bridge. A time-step adaptive simulation method for corrosion fatigue damage evolution of stay cables was proposed in this paper to describe the corrosion damage process of the stay cable accurately. The mechanical behavior of the bridge structure after corrosion damage of the cable-stayed bridges is studied, which provides a reference for the replacement of the cables of the elder cable-stayed bridges in service. Research on the Fatigue Degradation Process of Stay Cable Based on the Damage Model of Steel Strand
## 7 Conclusions and Future Work  
Two routing algorithms, namely energy-aware scalable reliable and void-hole mitigation routing (ESRVR) and cooperative energy-aware scalable reliable and void-hole mitigation routing (Co-ESRVR), were proposed for sparsely deployed wireless underwater sensor networks. The simulation backed results revealed that the strategies of selecting two hop neighbors, the backward transmission mechanism, holding time, and forwarding data in a cooperative fashion in the proposed algorithms enhanced the delivery of information packets to the end destination and reduced delay at the cost of high energy consumption. The chosen counterpart algorithm lacked these performance parameters. In the future, an intelligent mechanism will be used to shorten the path of the backward transmission mechanism so that the corresponding expense of energy and delay is optimized. In addition, the concept of autonomous underwater vehicles can be used to collect information from nodes that are completely isolated in sparse conditions.  
Figure 10: Delay.  
Figure 9: Delivery ratio.  
**Author Contributions:** [PERSON] proposed and implemented the main idea. [PERSON] and E.-u.-H.Q. streamlined the flow of the manuscript. A.U.R. responded to reviewers' comments. All authors have read and agreed to the published version of the manuscript.  
**Acknowledgments:** The authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding this work through research group NO (RG-1438-034).  
**Conflicts of Interest:** The authors declare no conflict of interest.
## 6 Conclusions  
In this paper, we have presented three intersection management policies (DRL, ATSC, and MP) in mixed traffic flow (CVs and RVs) with partial detection. In these scenarios, it was assumed that the wireless communication between platooned vehicles was perfect. The deep Q-learning model combines two aspects of reinforcement learning, DNN and Q-learning. Our main goal in this model is to optimize traffic signals and to reduce the waiting time of all vehicles. There are two types of vehicles in our model. Platooning vehicles are detected vehicles, and RVs are undetected vehicles. The model only collects data on detected vehicles (CVs) during training.  
Our contribution is to combine DRL and platoon formation to improve traffic efficiency in urban environments with different CV penetration rates. Therefore, traffic management agencies can apply this proposed approach to reduce waiting time at signalized intersections.  
To compare the effectiveness of the proposed model, we implemented two benchmark methods, ATSC and MP. These three scenarios were simulated at a signalized intersection to measure traffic metrics (waiting time, delay time, travel time, speed, and CO2 emissions). In addition, the model also tested the influence of the platoon by changing the number of vehicles in the platoon.  
In addition, platoon formation increases model efficiency and reduces the fluctuation of the reward during training. This is a very promising result in the future when the CV penetration rate is high. Experimental results in three scenarios (DRL, ATSC, and MP) with different CV penetration rates prove that DRL can handle all kinds of traffic. Although the results are different for each optimization scenario, DRL is a promising solution to apply to the overall optimization scheme.  
In this paper, we introduced a traffic simulation model for an isolated signalized intersection (single agent), and we believe that this could be applied to multi-agent scenarios to coordinate traffic lights. In the future, we plan to study complex road networks with many traffic signal phases and real traffic data in different ways (centralized and decentralized). In addition, we will devise a scenario that combines both signalized intersections and unsignalized intersections with different scenarios.  
The authors jointly proposed the idea and contributed equally to the writing of the manuscript. Writing: H.T.T.; coding: D.Q.T.; the corresponding author, supervised the research and revised the manuscript: S.-H.B. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.
# Numerical Simulation of Cavitation Erosion Aggressiveness Induced by Unsteady Cloud Cavitation
## 1 Introduction
Lloyd's Register Technical Investigation Department [20] applied Detached Eddy Simulation (DES) to simulate the cavitating flow and obtained good predictions of the eroded regions based on its own functions, but few details about them can be found in the open literature. Unlike the above mentioned erosion models in which the pressure wave is considered to be responsible for the cavitation erosion, some researchers assumed that the high-speed microjet was the main mechanism provoking the cavitation erosion. [PERSON] et al., [21] proposed an erosion model where the velocity of the microjet needed to exceed a certain threshold to be erosive for a given material. Following this work, [PERSON] et al. [22] calculated the erosion potential of a cavitating flow based the accumulation of the dimensionless intensity coefficient, defined by the ratio of the jet velocity to a threshold velocity value, on every element face along the total calculation time. The advantage of these approaches is that there are no critical requirements regarding the cell size and the time step and consequently the calculation time becomes more reasonable than for instance the methods included in the third approach. Nevertheless, they need to be further validated with experiments because they involve the use of some empirical coefficients. Among the erosion models discussed above, the model proposed by [PERSON] et al. [17; 18] has been widely used because it has been validated by various researchers and it provides a good agreement with the experiments [23; 24; 25; 26; 27]. Another reason for its popularity is that it has also been applied to industrial and engineering cases such as marine propellers [25] and pumps [28]. In spite of that, some uncertainties still need to be investigated and discussed to improve its performance and applicability. Therefore, the present work has been devoted to simulate systematically the erosion induced by unsteady cloud cavitation on the surface of a 2D hydrofoil and to investigate the factors influencing the erosion results including the selection of the cavitation model and of the driving pressure in the erosion model. Moreover, the main mechanisms of cavitation erosion have also been discussed by comparing the numerical results with the experimental observations. Finally, the influence of the free stream velocity and the dynamic behavior of the cavitation on the estimated erosion power has also been estimated based on the collapse efficiency.