esa-sceva/satcom-chunk-collection huggingface dataset:
# A Fingerprint-Based Verification Framework Using Harris and SURF Feature Detection Algorithms
## 3 Proposed Methodology
### Fingerprint Image Preprocessing
#### 3.2.3 Image Segmentation  
Segmentation is used to distinguish the image's fingerprint region (foreground) from the image's background area. When feature extraction is carried out on the background areas of an image, it often generates noisy and false features. Segmentation aims to ignore these background areas that facilitate efficient and accurate feature extraction [19]. A variance-based thresholding method is a very effective means for optimal threshold segmentation. In our work, any part of the image where the pixel intensity is less than 10% is considered as the region of no interest.
## 2 Swab Surge Modeling
### Physics-Based Modeling
#### 2.1.1 Pore and Fracture Gradient  
Figure 1 shows the pore and fracture pressure gradient window used for the swab and surge simulation. The experimental well was constructed with a 9 5/8'' casing set at 4000 m. For the swab and surge simulation study, the density of the drilling fluid was assumed to be at the mid-point between the tripping-in and tripping-out limits, as shown in the figure. The fracture gradient for the surging limit the casing was shown to be 2.06 specific gravity (sg), and the maximum pore pressure for the swabing limit was 1.93 sg. For practical work, one needs to compute the collapse pressure gradient and compare it with the pore pressure to determine the swabing limit. The collapse gradient was not calculated here because detailed information on the drilling formation was unavailable. Therefore, we assumed that the swab limit was based on the reservoir pressure. As shown in the figure, the fracture gradient increased as depth increased. However, this is not always the case. For instance, in the North Sea, there are weak formations, such as unconsolidated sandstone (e.g., Utsira sandstone), and tuff, which is volcanic ash (e.g., Balder formation). If these formations are present, the fracture gradient moves to the left side. Similarly, there are also mobile formations such as shale squeeze and salt formations. Hence, before commencing drilling operations, it is vital to have good knowledge of the geological formation to determine an appropriate well stability prognosis. Since there are many uncertainties that contribute to the well stability design, it is also important to include a safety margin for well collapse and fracture gradient curves. By doing so, one can predict the safe well pressure during static/circulation as well as during swab/surge operations. When the well stability window is narrow, the swab and surge speeds will be reduced. On the other hand, the wider window allows for higher swab/surge speeds, which reduce the NPT.
# Low-Profile Dual-Polarized Antenna Integrated with Horn and Vivaldi Antenna in Millimeter-Wave Band
###### Abstract  
In this paper, a dual-polarized antenna based on a substrate-integrated waveguide (SIW) horn antenna and Vivaldi antenna is proposed. The horizontal polarization (HP) is achieved by using the \(H\)-plane SIW horn antenna, while the vertical polarization (VP) is realized by a typical Vivaldi antenna etched on the surface of the SIW horn antenna. In front of the horn aperture, a dielectric lens is designed to optimize impedance matching and enhance directivity. Different feeding structures of the two polarizations are used to enhance the isolation between the two ports. The measured results demonstrate a 20.04-25.5 GHz (23.97%) overlapped dual-polarized impedance bandwidth, and the measured maximum gains of the HP and VP are 5.2 dBi and 8.2 dBi, respectively. A good isolation of 35 dB within the operating band is realized. The proposed dual-polarized antenna meets the demand to transmit and receive signals in two polarization directions simultaneously for wireless communication well.  
dielectric lens; dual-polarized antenna; SIW horn antenna; Vivaldi antenna +
Footnote †: journal: _Applied_  
0
Footnote 0: Copyright** © 2023 by the authors. Liconse MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))).
## 2 Literature Review
### E-Trust  
E-trust is a critical concept in the realm of digital commerce and interaction and represents the foundation of users' confidence in online platforms, services, and transactions. It encompasses their perceptions of reliability, security, and integrity, and reflects users' willingness to entrust digital environments with their personal information and transactional activities [26; 27]. Essentially, e-trust may shape user behavior and loyalty within the digital landscape, thereby influencing how individuals choose and interact with online platforms.  
In the absence of traditional trust cues such as physical presence or face-to-face interaction, e-trust becomes even more significant. Users rely heavily on indicators of digital security and reliability to assess whether they can safely engage in online transactions and activities. Factors contributing to e-trust include robust security measures, transparent data handling practices, and effective communication of privacy policies [28]. Collectively, these elements contribute to building a trustworthy digital environment in which users feel secure and confident about their interactions [29].  
The impact of e-trust extends beyond mere perception; it profoundly influences user engagement and loyalty. Customers who perceive a high level of e-trust in an online platform or service are more likely to engage frequently and conduct transactions without hesitation. E-trust fosters a sense of security and assurance, mitigating concerns related to privacy breaches, fraudulent activities, and the misuse of personal data. By cultivating a trustworthy digital presence, businesses not only enhance customer satisfaction, but also strengthen long-term relationships with their user base [30].  
Moreover, positive customer experiences significantly contribute to e-trust and the overall reputation of digital platforms. Satisfied users are more likely to perceive platforms as reliable and secure, and thereby exhibit increased e-trust [31]. This enhanced e-trust fosters customer retention because users who trust platforms are more likely to return for future transactions and recommend them to others. Such positive word of mouth promotion can drive organic growth, expand a platform's user base, and strengthen its position in the world of competitive digital commerce [32; 33].  
For businesses, understanding and cultivating e-trust is paramount for sustained success in digital commerce. Investing in technologies and practices that enhance security, transparency, and user confidence can yield substantial benefits in the form of customer loyalty and business growth [26]. As digital interactions continue to evolve, maintaining a strong foundation of e-trust will become essential for businesses aiming to thrive amid ever-changing consumer expectations and competitive pressures.
## 1 Introduction
### GEROS-ISS: The Payload  
The GEROS-ISS payload [2] will collect reflected navigation signals (GPS and Galileo, and eventually Compass and Beidou as well) at left hand circular polarization (LHCP) and right hand circular polarization (RHCP), as well as radio occultation of navigation signals (with a minimum antenna gain =9 dBi) at both RHCP and LHCP. GEROS will be installed in the upper deck of the Columbus module, the European module on board the International Space Station.  
The GEROS Antenna Beamformer (GAB, see Figure 2) antenna will consist of 2 dual-band multi-beam (4 beams min.) up- and down-looking arrays, mounted back-to-back, and pointing dynamically (from boresight to 77\({}^{\circ}\) out-of-boresight), in opposite directions towards the reflection points and their corresponding direct signals. The up- and down-looking antennas will be dual-polarization (RHCP and LHCP, respectively).  
The GAB will receive and form beams with GPS and Galileo signals at L1/E1 and L5/E5 (including signals from its overlay GEO satellites), and Beidou and Compass signals at B1/C1 and B5/C5. GAB's noise figure including antenna losses will be smaller than 3.5 dB.  
The GAB will include dedicated beams for dual-frequency Precise Orbit Determination (POD), conveniently tapered to avoid multipath from nearby structures as much as possible. The calibration-low noise amplifier (CAL-LNA) front-end will be placed in between the up- and down-looking arrays, and will be capable of providing the following antenna outputs at all specified frequencies: RHCPup and  
Figure 1: (**a**) View of the International Space Station, and (**b**) view of the Columbus module that will host GEROS-ISS payload in the upper deck.  
either LHCPdown or RHCPdown, or both RHCPdown and LHCPdown. Any signal could be routed to any receiver up to 16 times per second, to synthesize any polarization basis.  
The main observables generated by the payload will be: (1) near nadir altimetry power waveforms of LHCP GNSS-R signals at the two specified frequency bands, (2) scatterometry, (3) land/cryosphere observables (RHCP and LHCP waveforms interlaced up to 16 times per second [2]), (4) carrier phase evolution between the direct RHCP and the reflected LHCP signals for grazing angle altimetry, and (5) Radio Occultations and Polarimetric Radio Occultations.
# A New Maximum Likelihood Estimator Formulated in Pole-Residue Modal Model
## 2 Structure of the Combined LSCF-MLE-PMM
### Modal Identification with the LSCF and LSFD Estimators (1 st Step)  
This step aims at estimating the poles corresponding to the natural frequencies and modal damping ratios of the tested structures with the LSCF technique. This estimation is normally carried out by means of stabilization charts constructed by identifying models with increasing order. Once the poles are identified, they are subsequently used by the LSFD technique to estimate the modal residues in a LS sense. For completeness, a brief description of both techniques used in the first step of the identification process with combined LSCF-MLE-PMM is presented in following subsections.
## 1 Introduction
### Literature Review
These frequency deviations are analyzed later in a real time dynamic simulator platform. The local controls of generation units will react to frequency deviations to achieve a power balance and to maintain the grid frequency. In [20], the system frequency is introduced into the optimization problem. Particularly, the frequency-power (f-P) droop control is considered and a the maximum frequency deviation is constrained. These constraints apply for the steady state, but they do notconsider the transient behavior. An optimal power flow (OPF) problem that includes the frequency transient behavior is presented in [21], explaining the need to limit its deviations. However, the main assumption is that the frequency decreases linearly during the first few seconds until reaching the steady state. The typical frequency transient behavior usually presents an overshoot, as shown in [22]. Hence, the maximum frequency deviation during the transient may be greater than the deviation in the steady state. This effect is not considered in [21].
# Optical Wireless Fronthaul-Enhanced High-Throughput FC-AE-1553 Space Networks
## 4 Network Resource Allocation Algorithm Design for the HSN
### Bursty Traffic Allocation Scheme
#### Selecting Traffic  
For a traffic transmission with priority \(p\), the probability of being selected is \(\frac{pQ_{p,max}}{\sum_{p=1}^{p}pQ_{p,max}}\), and transmissions with the same priority have the same probability of being selected. Assume that there is an array WP, which serves as a sequential list of executed transmissions, and the contents of the array are pointers to bursty transmissions with different priorities, \(Addr(p,q_{p})\). The number of implementations per transmission is the value of the priority level, as shown in Figure 9.  
Figure 8: Bursty traffic schedule.
## 3 Problem Statement and Schedule-Based Network
### Schedule-Based Network Representation  
In order to figure out passenger's choice between different trains when diversified service trains are operating on the line, a schedule-based network \(G=(V,E,T)\) is used to represent the train-based network under cross-line and skip-stop operation. \(V\) is the set of spatiotemporal nodes. \(E\) is the set of arcs connecting spatiotemporal nodes. \(T\) denotes the time attributes of nodes and arcs. Basic notations related to schedule-based network are listed in Table 1. A schedule-based network of one O-D pair is shown in Figure 3.  
Figure 1: “\(\gamma\)” type cross-line operation between the state railway and suburban railway.  
Figure 3: Schedule-based network of one O–D pair under cross-line and skip-stop operation.  
Figure 2: Train stop plan.  
There are four types of spatiotemporal nodes which include trip origin and destination nodes, train arrival, and departure nodes. The notation and definition of nodes are described in Table 1. And there are five types of arcs in the network described as follows.
# Research on Advancing Radio Wave Source Localization Technology Through UAV Path Optimization
## 2 Literature Review
### Fingerprinting-Based Localization  
Fingerprinting-based localization has gained significant attention in recent years due to its robustness in environments where traditional geometric methods, such as multilateration and triangulation, often fail--particularly in non-line-of-sight (NLoS) conditions common in urban or indoor settings. This method operates in two phases: the offline phase, where signal features such as received signal strength indicator (RSSI), angle of arrival (AOA), or elevation of arrival (EOA) are collected at known reference locations to construct a database, and the online phase, where incoming measurements are matched against the database using statistical methods to estimate the target position. Recent studies have demonstrated the effectiveness of fingerprinting-based localization. For example, [PERSON] and [PERSON] [3] proposed a method utilizing multipath signal features in urban NLoS environments, improving robustness by applying machine learning to the fingerprinting process. [PERSON] et al. [4] conducted a comprehensive survey of Wi-Fi-based indoor fingerprinting systems and compared various algorithms under different conditions. [PERSON] et al. [5] examined outdoor localization in NLoS environments using UAVs and found that aerial sensing helped improve coverage and accuracy. Despite these advantages, fingerprinting remains limited by the effort required to build and maintain the signal database, and its sensitivity to environmental dynamics. To address these challenges, recent research has explored the use of UAVs as mobile sensors to enhance spatial coverage and ease database construction [6]. This study builds on these trends by proposing a hybrid fingerprinting model that integrates RSSI, AOA, and EOA, and by optimizing UAV flight paths to further enhance estimation performance.
# Efficient On-Off Keying Underwater Acoustic Communication for Seafloor Observation Networks
## 5 Conclusions  
For the applications of the SON, a novel non-coherent UAC multi-carrier transmission scheme adopting the OOK modulation was proposed in this paper. Firstly, we verified the high spectral efficiency of the OOK modulation by calculating the channel capacity under the flat Rayleigh fading channel. The lower bound of \(E_{b}/N_{0}\) is 9.6 dB when the capacity is 0.5 bit/s/Hz. To approach the channel capacity, an ACC was coupled with the OOK modulation to facilitate the turbo-iteration, and an IrCC was designed to match the EXIT curve of the ACC-OOK demapper and thus lowered the iterative SNR-threshold. A low complexity ITE algorithm was also proposed to improve the iterative decoding performance. The simulation results showed that, under the flat Rayleigh fading channel, the proposed scheme can achieve reliable communication when the \(E_{b}/N_{0}>12.5\) dB and the gap to the channel capacity was only 3 dB. Compared with the conventional scheme adopting RSC without ITE, a performance gain of 1.8 dB was obtained. Furthermore, as an important preliminary work of sea trial, the placement of the communication nodes near the seafloor was analyzed to ensure good communication quality. Finally, the proposed scheme was verified by the SON experimental data. Reliable communication has been achieved when \(E_{b}/N_{0}>9.2\) dB, and the achieved spectral efficiency was 0.35 bit/s/Hz with frequency band 6-10 kHz at the communication distance of 2500 m.  
Conceptualization, Y.Y., Y.W., and D.L.; methodology, Y.W. and M.Z.; software, Y.Y. and Y.W.; investigation, Y.Y. and Y.W.; resources, M.Z.; writing--original draft preparation, Y.Y., Y.W., D.L., and J.T.; writing--review and editing, Y.Y., D.L., and J.T.; visualization, Y.Y., Y.W., and D.L.; supervision, M.Z. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the National Natural Science Foundation of China under Grants 61971472, 61871114 and 61471351, in part by the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant XDA22030101, in part by the National Key R&D Program of China under Grant 2016 YFC0300300, in part by the Fund of Acoustic Science and Technology Laboratory, Harbin Engineering University, in part by the Open Funds of State Key Laboratory of Acoustics, Chinese Academy of Sciences, under Grant SKLA201805, in part by the China Scholarship Council, under Grant 201904910081, and in part by the Innovation Special Zone of National Defense Science and Technology of China.  
The authors declare no conflict of interest.  
Figure 12: Performance comparison of three encoding and decoding schemes in the actual channel, \(k=1000\).
# An Overview of Distributed Firewalls and Controllers Intended for Mobile Cloud Computing
## 3 SDN, NFV, and CASB Technologies
### Cloud Access Security Broker (CASB)
#### 3.3.1 Pillars of CASB  
Figure 4 shows the CASB framework. It presents the pillars of CASB, including control and visibility into cloud application usage, data security and compliance features like Data Loss Prevention (DLP), threat protection mechanisms, and detailed risk assessments. It also highlights the critical function of CASB in bolstering security and ensuring compliance within cloud environments.  
1. Control and Visibility: CASBs enable insight into an organisation's use of cloud applications, including tracking and monitoring user actions, data transfers, and cloud application settings.
2. Data Security and Compliance: CASBs provide DLP features to prevent unauthorised access or the exchange of sensitive data.
3. Threat Protection: CASBs identify and manage threats in real time by using sophisticated threat detection, behaviour data analysis, and machine learning.
4. Detailed Risk Assessment: CASBs perform risk assessments by examining cloud application security posture and determining related hazards.
# Wi-Senser: Contactless Head Movement Detection during Sleep Utilizing WiFi Signals
## 3 System Design
### Data Collection  
We conducted a data collection experiment in the laboratory using an 802.11n WiFi network, with a commercial WiFi router (TP-Link WDR5620, Shenzhen city, Guangdong Province, China) set as the transmitter (TX) and a Lenovo laptop equipped with an Intel 5300 network card as the receiver (RX), as shown in Figure 2. The network card has three antenna interfaces, and we connected external antennas to the receiver to enhance the signal strength. The distance between the transmitter and receiver was set to 2.5 m, and the packet transmission rate of the transmitter was set to 20 pkts/s. During the experiment, volunteers lay on a long table between the transmitter and receiver and freely rotated their heads (i.e., rolling their head in a supine position). We used the tool provided in the literature [14] to modify the firmware and driver of the receiver's network card to obtain CSI measurements of 30 subcarriers in the 2.4 GHz WiFi signal. Specifically, the received single CSI measurement is a complex matrix of size \(30\times N_{TX}\times N_{TX}\), where \(N_{TX}\) and \(N_{RX}\) are the numbers of transmitting antennas and receiving antennas, respectively.
# Early Fire Detection on Video Using LBP and Spread Ascending of Smoke
## 3. Results
On the other hand, if the threshold value is too large, the system response may not be able to respond as quickly as required in early fire detection applications. In our experiments, a threshold of 4 s was selected such that the time period for the movement analysis was 0.5 s, i.e., \(\tau=fps/2\), where fps is the number of frames per second. In the videos without smoke, the alarm was not activated because false positives that may occur were not connected in clusters. Note that these detection rates heavily depended on the training and the parameters used in the neural network that must be considered: the lighting conditions, the contrast in the scene, occlusions in the foreground and various factors that affect smoke detection. The boundary regions containing the smoke column were properly detected by the proposed algorithm because of their characteristics, i.e., expansion, dilution, translucency and texture.
# Design and Fabrication Technology of Metal Mirrors Based on Additive Manufacturing: A Review
## 3 Design Technology of Additively Manufactured Metal Mirrors  
Mirrors' weight is an important factor when highly dynamic scanning applications are desired or for space optical system applications. Thus, a light weight is a key parameter to the optomechanical design of metal mirrors. How to match the relationship between weight and structural stiffness is the technical difficulty of mirror structural design. As Section 1 mentioned, lightweight structures of mirrors include the arched mirror, open-back mirror, and sandwich mirror. It is necessary to consider various factors, such as fabricating difficulty, cost, and processing time. The introduction of AM provides mirrors' structural design more freedom. DfAM methods can offer a good compromise between mechanical functionality and material usage. And a well-thought DfAM strategy is a major factor in the economy and the success of an AM part. In this section, AM metal mirrors with different internal lightweight structures are given, including conventional structure, TO structure, lattice structure, and Voronoi structure. All the structures are explained and compared in detail according to the corresponding research results. It is worth noting that these internal structures can be combined in practical applications, such as TO and lattice and TO and Voronoi.