esa-sceva/satcom-chunk-collection huggingface dataset:
# Named Entity Recognition for Sensitive Data Discovery in Portuguese
## 4 Experiments and Results  
As we saw before, different methodologies were applied to the NER task: Ruled-Based Models, Lexicon-Based Models, and Machine Learning Models. However, all experiments and tests performed were carried out on a single machine, using Python Language. As a consequence of not having any corpus for evaluation that contains all the classes of entities that were worked on in this work, the different techniques were used for different classes of entities. The datasets are crucial for the success of any Machine Learning work, but the NER task for the Portuguese language presents several problems due to the lack of training and testing datasets. The only freely available Portuguese dataset annotated with classes of entities was the one developed for the HAREM events [24]. One other Portuguese dataset is the SIGARRA News Corpus, annotated for named entities, consisting of a set of 905 news manually annotated ([[https://hdl.handle.net/10216/106094](https://hdl.handle.net/10216/106094)]([https://hdl.handle.net/10216/106094](https://hdl.handle.net/10216/106094))), which was taken from the SIGARRA information system at the University of Porto ([[https://sigarra.up.pt](https://sigarra.up.pt)]([https://sigarra.up.pt](https://sigarra.up.pt))). From these two datasets, none presents all the classes of entities used in this work, and mainly in the two corpora, neither of them respects its context, seeing that the majority of the documents were either News or Web pages' text. For this reason, one of the key aspects of this work was the construction of the test corpus, the DataSense NER Corpus. This corpus was built with the aim of understanding the results obtained when applied to the real context of the DataSense Project.  
All classes discovered through Rule-Based models, as well as the Profissoa (Job) and Med (Medical data) classes can only be evaluated by the DataSense NER Corpus. The class Valor (Value), which is present in both Lexicon-Based and Machine Learning methods used, was only trained withand analyzed on the corpus HAREM, since the corpus SIGARRA does not have this entity class annotated. All other classes of entities could be evaluated with both the HAREM and SIGARRA corpora, which allowed for a comparison between the results obtained. The evaluation of the task of Named Entity Recognition is based on the metrics: Precision, recall, and f1-score. Table 2 shows the results of all the tests performed, while the experiments and results are detailed individually in the following subsections.
# A Long-Range Lidar Optical Collimation System Based on a Shaped Laser Source
###### Abstract  
Semiconductor near-infrared lasers have been widely used in lidar systems. However, various source types have different shapes and divergence angles, causing more difficulties for long-distance detection. In this paper, an optical collimation system is designed for a long-range lidar system with a shaped laser source (the wavelength is 905 nm, the emitted spot size is 50 \(\upmu\)m long by 10 \(\upmu\)m wide, and the divergence angles are 33 degand 15 deg, respectively, which are unconventional). On the basis of the traditional method of aspheric lens setting, a pair of asymmetric aspherical lenses were designed using an extended polynomial. The simulation results show that the spot shapes are all close to circular from 100 mm to 30 m and the spot size always remains the same value. The corrected optical system is put into the designed lidar system for verification. It results show that the average divergence angles in the long and short axis directions are 0.06 degand 0.07 deg, which satisfy the project requirements. This optical system designed provides a collimation scheme and expands the application of vehicle-mounted lidar in the field of long-range detection.  
lidar; optical system design; aspheric surface; long distance +
Footnote †: journal: Applied sciences
# Comparison of the Sentinel-3A and B SLSTR Tandem Phase Data Using Metrological Principles
## 6 Conclusions  
In conclusion, the tandem phase has proved to be a valuable addition to the understanding of the SLSTR L1 and L2 SST data. Looking at the same location twice in a very short period of time with essentially the same viewing geometry allows for a comparison with a level of detail challenging to achieve with other common validation methodologies. Additionally, applying metrological principles to the comparison, facilitated by the availability of the uncertainties in the L1 and L2 SST products, has enabled a more quantified analysis of the derived results.  
For the L1 radiometric comparison, good performance was found in nadir view TIR channels S7, S8 and S9, and the oblique view S7. However, in the S8 and S9 channels, in the oblique view, a strong nonlinearity effect was found, as previously observed in the pre-flight analysis. A correction was proposed for this effect, which is recommended for further investigation.  
The tandem data have also been useful in finding small differences in SST, and by looking at them as a function of difference aspects of the SST retrieval process (e.g., retrieval algorithm, quality level, cloud probability), some new processes related to SST bias and uncertainty have been identified. These include the nature of the SST retrieval as a function of quality level as well of as a function of cloudy probability, both of which have not been studied at this level of detail before. The Tandem data have also proven to be useful in finding problems with the operational retrievals related to the current set of coefficients and should be included in subsequent updates to the SST retrieval algorithms.  
Conceptualisation, S.E.H., J.P.D.M., D.S., E.R.W. and C.D.; Formal Analysis, S.E.H., J.P.D.M., D.L.S., E.P., and R.Y.; Writing--Original Draft Preparation, S.E.H. and J.P.D.M.; Writing--Review and Editing, D.L.S. and E.R.W. All authors have read and agreed to the published version of the manuscript.  
This work has been performed under the European Space Agency Science and Society Contract 4000124211/18/I-EF \"Sentinel-3 Tandem for Climate\". The work was also partly funded through the Metrology for Earth Observation and Climate project (MetEOC-3), Grant No. 16 ENV03 within the European Metrology Programme for Innovation and Research (EMPIR). EMPIR is jointly funded by the EMPIR participating countries within EURAMET and the European Union.  
The authors would, firstly, like to thank ACRI-ST for their help in the creation and distribution of the tandem data archive and for access to their data analysis platform. Additionally, we would like to thank the SLSTR Mission Performance Centre for their cooperation and collaboration during the study. Finally, we would like to thank [PERSON] for his coordination of the _Sentinel-3 Tandem for Climate_ project that this study was part of.  
The authors declare no conflict of interest.
# Study on Dynamic Loading Characteristics of Rock Containing Holes
## 2 Numerical Model
### Numerical Model of the Split Hopkinson Pressure Bar System  
In this study, a dynamic uniaxial Split Hopkinson Pressure Bar (SHPB) setup utilizing Particle Flow Code in 2 Dimensions (PFC2D) was constructed, as depicted in Figure 5. This setup includes three main elements: a striker bar, an incident bar, and a transmission bar, with lengths of 300 mm, 1500 mm, and 800 mm, respectively. To facilitate uniform stress wave transmission through the specimen, the diameters of both the incident and transmission bars were standardized at 50 mm, aligning with the specimen's end diameters. Five observation points, labeled A to E, were strategically positioned on the incident and transmission bars to monitor dynamic stress wave behavior. Additionally, to enhance stress wave transfer and reduce experimental discrepancies, the particles at the interface between the bars and the specimen were meticulously arranged, possessing a radius equivalent to the smallest particle in the specimen.  
A cylindrical rock specimen, measuring 50 mm in diameter and 50 mm in length, was fabricated with internal particles designed to be small and uniformly distributed, featuring particle sizes from 0.15 mm to 0.25 mm and a particle size ratio of 1.66. The porosity of the specimen was set at 0.15, adhering to a slenderness ratio of 1.0. The particle  
Figure 4: Behavior and rheological components of the (**a**) Contact Bond Model; (**b**) Parallel Bond Model (PBM).  
Figure 5: Schematic diagram of the SHPB numerical model.  
deletion method facilitated the creation of voids within the model [46] for its effectiveness and rapidity, focusing on precise locations for particle elimination. While this approach primarily removes particles from the center of the designated area, leading to a relatively rough borehole surface, the markedly smaller particle sizes compared to the diameter of the holes ensured that the influence on the experimental results was negligible.  
Despite previous findings suggesting that the influence of the numerical model on the specimen's mechanical behavior is minimal in experiments when the smallest dimension of the model is at least five times greater than the average particle diameter, with a minimum of five particles spanning the end faces [47; 48; 49], the authors of this study chose to utilize smaller particles to increase experimental precision. This strategy guaranteed that both the smallest dimension of the specimen and the average particle size were adequately large, facilitating a more accurate depiction of the model's mechanical damage features from a macroscopic perspective throughout the loading phase. As a result, the impact of particle size on the simulation's outcomes was minimized, enhancing the accuracy of the experimental findings.
## 4 Improved Tight Combination Model
### Convergence Analysis of Combination Error
#### 4.5.3 Dynamics Model of Double-Loop Cumulative Error  
In this study, an IMU was introduced to reduce the positioning error caused by NLOS interferences. However, since the second integrations by the time of IMU acceleration leads to an accumulated error, the UWB error propagation dynamics model and IMU position cumulative error in this study were used to establish the double-loop cumulative error dynamics model (DCEM), as shown in Equations (31) and (32).  
\[e_{DEPM}=\omega_{1}E_{1}+\omega_{2}E_{2} \tag{31}\]  
\[e=\omega_{UIWB}e_{DEPM}+\omega_{IMU}e_{IMU} \tag{32}\]  
In the \(i\)th filtering fusion, the state vector at \(k-1\) moment is used to derive the estimate of the prior error state at k moment.  
\[e_{k}^{-}=F_{1}X_{k-1}^{\epsilon} \tag{33}\]  
where \(F_{2,3}\) is the first-order expression of each part of the state transition matrix \(F\). In this case, the error state vector at moment k can be kinked with the error state vector at moment \(k-1\).  
In the discrete positioning system, the error is constantly iterated in the system state equation. When the iteration reaches the \(k\)th moment, the IMU error is eliminated back to zero, and the \(j\) at the next moment is set as \(j+1\) and \(i\) as \(i+1\). In this way, the convergence of IMU cumulative error is effectively controlled.
## 3 Earth Surface Modelling Advances and Links with EO Datasets
### Land-Surface Reservoirs
#### 3.1.2 Seasonal Snow Cover
The detection of snow on the surface was one of the first applications of EO data associated with surface characteristics and it is currently one of the surface variables with longer observed datasets using remote sensing. Furthermore, it is the main direct data source in land-surface assimilation in several operational weather forecasting centers [112]. In addition to snow presence, snow mass is an important water reservoir and there have been many studies focusing on the retrieval of snow mass from satellite [113]. Monitoring of snow cover area is well established based on optical data, whereas current Snow Water Equivalent (SWE, i.e., the total water mass in liquid equivalent) products mostly rely on passive microwave measurements [114]. Active microwave measurements at high frequency (Ku-band) are sensitive to volume scattering of the dry snow as well as the wet or dry status of the snow cover [115]. They are therefore also relevant for future mission concepts dedicated to accurate snow water equivalent retrieval from space. Dry snow is, however, largely transparent at lower frequencies (C or L-bands), making it a challenge to observe snow from space [116; 117]. Physically-based forward models that rely on a good understanding of the electromagnetic interactions with the snowpack are best suited to obtain consistent retrievals of snow macrophysical and microphysical properties or for data assimilation in NWP systems. The new generation of snow forward models, such as the Snow Microwave Radiative Transfer (SMRT), account for multi-layer snow emission and backscatter [118]. Using satellite data from microwave sensors with appropriate multi-layer forward modeling and retrieval approaches for the snow microwave properties characterisation is of great interest to support physically based multi-layer snow model developments. Recent studies showed that SMOS data [119] and ground-based L-band measurements [120] could give insight on snow density and liquid water in snow using a two stream approach. This is promising for constraining model errors in snow depth that are not associated with snow mass but with its state of compaction.
# A Review of Document Image Enhancement Based on Document Degradation Problem
## 3 Document Image Degradation Methods
### Page Smudging Problem
For the generator, a U-Net-based structure is used, and the addition of bypass links reduces information loss and allows the model to learn more advanced features. For the discriminator, a simple multilayer convolution structure is used. The model cannot only deal with degradation problems such as page smudging but also has better results in watermark and blur removal for document images. Although it has better results on different document enhancement tasks, when dealing with binarization tasks, it is more time-consuming to train it several times in processing the problem to obtain better results because of the need to manually change the variables in the loss function.
# Design and Simulation of On-Orbit Assembly System Based on Insect-Inspired Transportation
## 1 Introduction
Additionally, there have been multi-robot collaborative motion planning algorithms for space robots and robot systems that differentiate between auxiliary and primary tasks. Nevertheless, a number of issues, including enhancing the intelligence of space robots, facilitating robot task allocation, and validating space robot systems on the ground, remain. Therefore, further research is required to strengthen the cooperative, perceptual, and interactive capabilities of space robots and to develop more accurate and viable ground validation methods to ensure successful in-orbit assembly [31; 32]. The purpose of this paper is to propose an effective robot assembly plan that can achieve in-orbit assembly of super large components. The proposed assembly plan has significant theoretical and practical significance and will play an important role in future in-orbit assembly missions. In terms of research methods and ideas, we adopted a solution that combines legged robot mobility and mechanical arm gripping to complete three stages, namely, unloaded roaming, loaded roaming, and loaded assembly. We also established the dynamic model of the robot's movement and assembly process and adjusted the impact of flexible elements on the assembled unit through dynamic simulation. The proposed robot assembly plan in this paper proves the feasibility and effectiveness of in-orbit assembly of super large components. Moreover, the adoption of robots for rail assembly can enhance efficiency, diminish expenses and hazards, and refine spacecraft design and structure. The established models and simulation findings are of immense significance for the development and enhancement of robot assembly design in the future.
# Intelligent Control System to Irrigate Orchids Based on Visual Recognition and 3D Positioning
## 3 Results and Discussion
### Water Flow Control Experiment of Solenoid Valve  
This research also recorded experimental results in Figures 26 and 27, to relate the watering amount (g) with the duty time for valve opening (s). It was measured by the way that the duty time for valve opening started from 3 s and increased sequentially with the one-second interval. The experimental results are linear in the range between 4 and 11 s; hence, the relationship between the watering amount and the duty time for valve opening, formalized in Equation (3), is adopted to control the amount of watering.  
\[\text{y}=0.2313\text{x}+1.57. \tag{3}\]  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Measurements** & **Point 1** & **Point 2** & **Point 3** & **Point 4** \\ \hline X-axis average measurement (cm) & 10.16 & 10.18 & 25.1 & 25.16 \\ Y-axis average measurement (cm) & 30.2 & 35.2 & 30.16 & 35.12 \\ Z-axis average measurement (cm) & 13.22 & 13.32 & 13.2 & 13.18 \\ X-/Y-/Z-Axes absolute error (cm) & 0.16/0.2/0.22 & 0.18/0.2/0.32 & 0.1/0.16/0.2 & 0.16/0.12/0.18 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Measurement results of seedling center.  
Figure 27: Relationship of duty time for valve opening (4 to 11 s) and watering amount.
## 5 V2X Technology in the Context of SAE Levels of Autonomy  
The integration of V2X technology holds significant promise in advancing the capabilities of self-driving vehicles across the SAE levels. At levels where the human operator remains responsible, V2X can enhance driver assistance systems by providing real-time information about the road conditions, the traffic congestion, and the potential hazards, enabling the automated system to make more informed decisions. Complex ADAS systems can benefit from V2X in cooperative perception, allowing vehicles to exchange sensor data and collaborate in detecting and tracking objects. This can enhance the accuracy and the reliability of object recognition and improve the overall situational awareness of the automated system.  
On the other hand, at higher levels of autonomy, V2X plays vital role in facilitating safe and efficient control transitions between the automated system and the human driver. Through communication with traffic infrastructure and other vehicles, V2X provides critical information to prepare the system and the driver for the handover of control. V2X is designed to enable highly cooperative and coordinated behaviors among self-driving vehicles. By sharing intentions, trajectories, and sensor data, V2X allows smooth merging, platooning, and intersection crossing, leading to improved traffic flow, reduced congestion, and enhanced safety.
# Automatic Bridge Design Parameter Extraction for Scan-to-BIM
## 1 Introduction
The scan-to-BIM process requires parameter extraction to obtain numerical data such as height, length, and width. Although research on extracting numerical information from PCD has been conducted, it has focused only on universal geometric shapes [26]. It is relatively straightforward to extract parameters from a typical building because it is composed of universal geometric shapes. In contrast, the components of bridges are complex and not universal, thus complicating automated parameter extraction. As a result, this extraction is currently performed manually, which consumes time and resources. This study developed a method to automatically extract design parameters of bridges, such as the heights, lengths, and widths of components, from PCD. The proposed method consists of three steps: (1) noise reduction, (2) 3D transformation, and (3) design parameter extraction. An experiment was conducted to validate the performance of the proposed method using PCD obtained through the LiDAR scanning of an existing bridge. The proposed method is expected to reduce the time and expense associated with current scan-to-BIM processes.
## 1 Introduction  
Underwater acoustic communication has been under research for at least half a century now. One of the first underwater communication devices was the underwater phone, developed for the US Navy after World War II [1].  
During the last decade, this form of communication has received increasing attention, owing to its many scientific, military and commercial applications. These applications range from tactical surveillance to the study of marine life and include unmanned vehicle communication, pollution monitoring, oil extraction monitoring and aquaculture monitoring.  
Electromagnetic waves, optical waves and acoustic waves have been successfully used in underwater wireless sensor networks (UWSNs) [2,3]. Nevertheless, radio frequency (RF) waves are affected by high attenuation in water (especially at higher frequencies) [2], thus requiring high transmission power and large antennae [4]. Optical waves can be used to achieve ultra-high-data-rate communications (Gbit/s), but are rapidly scattered and absorbed in water, so they are only reliable for short-distance links [2].  
In contrast, acoustic waves enable communications over long-range links, because they suffer from relatively low absorption. Thus, this is the preferred technology to develop reliable UWSNs [3] and is the main focus of this paper. In [5], the characteristics of the acoustic underwater channel and the difficulties in underwater communication are discussed. The differences between acoustic and radio-based communication open a new research field in UWSNs.  
Despite the increased complexity of acoustic transmissions when compared to RF transmissions, researchers have made enormous advances since the underwater telephone. Nowadays, commercially available underwater modems are able to transmit up to 30 kbps over distances ranging from a hundred meters to a few kilometers [6,7].  
Given these advances in underwater transmission capabilities, an increasing amount of research has been focused on building networks of underwater nodes. Given the long propagation delays, direct use of medium access control (MAC) and routing protocols of previously existing RF networks is not advisable. Hence, a great deal of research has been focused on this issue. Moreover, some of these protocols require time synchronization and localization. These problems must be revisited, because propagation time is not usually taken into account in RF networks.  
This survey aims to provide a comprehensive overview of the current research on underwater wireless sensor networks, focusing on the lower layers of the communication stack, and envisions future trends and challenges. It analyzes the current state-of-the-art for the physical (Section 2), MAC (Section 3) and routing layers (Section 4). In addition, it summarizes their security threads and surveys the currently proposed studies. Finally, conclusions on the current state-of-the-art in UWSNs and future challenges to be faced are presented.
## 4 Enabling Technologies for FSO Communication
### Cooperative Relaying
#### 4.8.2 Cooperative FSO Transmission Schemes  
In this section, we explore the synchronous and asynchronous cooperative FSO transmission schemes. These schemes represent critical strategies for enhancing the performance and reliability of FSO systems. Synchronous cooperative transmission involves the precise coordination of multiple transmitting sources, ensuring that their signals reach the Rx in a well-aligned manner. This alignment can significantly improve signal quality and reduce error rates. Conversely, asynchronous cooperative transmission schemes do not require such strict timing coordination, offering greater flexibility and robustness in environments where perfect synchronization is challenging. By comparing these two approaches, we aim to highlight their respective advantages, limitations, and potential applications in various FSO communication scenarios.