esa-sceva/satcom-chunk-collection huggingface dataset:
# Fuzzy Risk Evaluation and Collision Avoidance Control of Unmanned Surface Vessels
## 3 Design of Smart Collision Avoidance Control System for USVs
### Generation of Collision Advoidance Course
#### 3.3.4 Fuzzy Reduction Speed Generator  
The alternative way to develop a collision avoidance indicator is the design of a fuzzy-based speed reduction generator. The proposed speed reduction generator was built using the level of the sailing velocity after deceleration, and the amount of time was taken for this drop in velocity, as shown in Figure 14. When the speed reduction generator was triggered, an optimal velocity (\(V_{d}\)) will replace \(U_{d}\) in (49) and (50) to avoid a collision.
# Time Modulated Arrays: From their Origin to Their Utilization in Wireless Communication Systems
## 2 State of the Art
### TMA Design under a Signal Processing Perspective
#### 2.3.2 Towards Using TMAs in Wireless Communication Systems
Notice that, for the sake of simplicity, channel estimation and equalization are assumed to be perfect. Note also that the non-linear operation carried out by the TMA allows for employing a single RF branch (with increasing bandwidth) followed by a single analog-to-digital converter (ADC) (with a higher sampling rate) to exploit \(L\) signal replicas impinging at the TMA. Consequently, the complexity of the receiver structure is simplified and, above all, its power consumption is reduced. The investigations in [77] also lead to the detection of certain limitations of rectangular pulses when the aim is to achieve a flexible and efficient beamforming with TMA. Such vulnerabilities are directly related to the frequency response of rectangular pulses (Chapter 3, p89, [78]): a minimum main-lobe width and a modest side-lobe level (\(-13\,\text{dB}\)), together with a slow (first order) asymptotic side-lobe decay. In fact, taking as the starting point the weaknesses of rectangular pulses when applied to harmonic beamforming, the following two contributions were introduced in [79]:  
* A type of pulses that are more suitable for harmonic beamforming with TMA: the so-called sum-of-weighted-cosine (SWC) pulses [80]. * Based on the previous pulses, a new family of beamforming TMA, termed ETMA, is characterized and evaluated in terms of efficiency by properly comparing it to conventional beamforming TMA based on rectangular pulses. Figure 4: Block diagram of a system consisting of a conventional linear digital transmitter equipped with an omni-directional antenna and a receiver with a TMA designed for exploiting channel diversity at the receiver through maximum ratio combining (MRC). Figure 5 shows the block diagram of an ETMA where the static excitations \(I_{0},\ldots,I_{N-1}\) of the array are time-modulated by more sophisticated periodical waveforms parametrized by \(\xi_{n}\) (normalized pulse durations), \(o_{nq}\) (normalized pulse time shifts), and \(a_{nk}\) (pulse weights), \(n\in\{0,1,\ldots,N-1\}\), \(q\in\{0,\pm 1,\ldots,\pm L\}\), and \(k\in\{0,1,\ldots,K\}\), where \(N\) is the number of antenna elements, \(L\) is the order of the highest exploited harmonic, and \(K\) is the order of the pulse. A common denominator of these recent investigations [72; 75; 77; 79] is that TMA are analyzed and evaluated not only from an antenna outlook, but also from a signal processing perspective.
# Improving Water Efficiency in a Municipal Indoor Swimming-Pool Complex: A Case Study
## 2 Materials and Methods  
### The Case Study  
Braganca (Latitude: 41\({}^{\circ}\)48\({}^{\prime}\)20\({}^{\prime\prime}\) N; Longitude: 6\({}^{\circ}\)45\({}^{\prime}\)25\({}^{\prime\prime}\) altitude: 673 m) is the principal city of northeast Portugal, with 24,078 inhabitants [25]. The climate is continental with Mediterranean influences. Annual mean precipitation is around 700 mm per year, occurring mainly in autumn and winter, but in a very irregular pattern [26]. Two reservoirs designed with a 99% supply guarantee rate are the base of the urban water supply. However, because this value was calculated without considering the changing climate conditions, it will likely be insufficient for future water supply [27]. According to the information provided by the municipality, the water demand per year is around 3757.615 m\({}^{3}\). Approximately 80% of this water is for domestic consumption, whereas the remainder is for commercial and industrial purposes. Indeed, Braganca is one of the Portuguese cities with the highest water demand: more than 262 L/(inhabitant/day) [28].  
The Braganca indoor municipal swimming pool complex was launched in 2003. This complex includes two covered pools (competition and learning pools), with barriers around the pool to collect and reuse any splashes or overflows (Figure 1; Table 1) and the following installations: male, female, and staff dressing rooms, showers, WCs, Cafe, first aid room.  
Figure 1: General view of the competition (**A**) and learning (**B**) pools.  
The water for the pools comes from the public water supply system. It is simultaneously heated and treated with chlorine through the recirculation system, and continuously recycled in sand filters (Table 1). These filters are backwashed every two days. According to information provided by the Municipality concerning the period from 2016-2018, the average number of users per year is 45,957. October and November are the months with the highest number of users, with an average of 6142 users per month, whereas August and September are the months with the fewest users (732 users per month). The closure of the complex between these two months for pool maintenance and cleaning explains the latter value.
## 6 Conclusions and Future Work  
This research paper proposes the utilization of the Wiener-Granger causality theory, together with the CBIR self-organization analysis. The novel proposal is applied to image retrieval of 6 natural scenes that are: coast, forest, mountain, field, river/lake, and sky/cloud. Taking into account the proposed methodology, from the causality matrix, it was fruitful to find a set of descriptors that represent a type of natural scene. Texture patterns could be defined from an automatic set of reference textures. From the self-organizing attributes, it is now possible to classify any unknown natural scene.  
With the proposed methodology, 100% image retrieval is achieved for the three data sets. The proposal is advantageous since no prior labeling or knowledge of the natural scenes content is required.  
The proposed methodology gives 100% of recovery on vision image database. Thus, the proposal works at 100% for rotated images and scaled images; performance falls down to 50% for noised images.  
Another important contribution of our proposal is the ability to recover natural scenes by some contained element, i.e., water, cloud, foliage, and rock. The percentage of recovery of these natural elements is above 70% using the proposal presented in this research paper.  
The experimental results show that our proposal outperforms the most competitive methods reported by [PERSON] [28], [PERSON] [29], [PERSON] [30], [PERSON] [12]; with an average recognition of 100% for the same image datasets.  
Future work will seek the entire methodology implementation in parallel computing; using CPUs and GPU technology, which could perform the scene recovery task efficiently in the image feature extraction stage. The parallel algorithms might also help to jointly analyze the textures of the image seeking to characterize the image and its associations with the paradigm of visual understanding.  
Writing-review and editing, C.A.-C., C.B.-A.; investigation, C.B.-A., C.A.-C. and E.R.-M.; resources, A.F.-R.; writing--original draft preparation, C.A.-C. and C.B.-A.; validation, C.B.-A.; conceptualization, C.A.-C. and C.B.-A.; formal analysis, C.B.-A., E.R.-M. and A.Z.-L.; methodology, C.B.-A. and C.A.-C.; C.A.-C. supervised the overall research work. All authors contributed to the discussion and conclusion of this research. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare that there is no conflict of interests regarding the publication of this paper.
# Quality Behaviour of Turnouts: Comparison, Problem Specification and Recommendation of Measures
## 2 Methodology
### Data-Based Turnout Assessment
#### 2.1.3 Evaluation of Rail Surface Irregularities  
When it comes to causes of poor turnout behaviour, short-wave irregularities must be considered. These effects lead to dynamic load effects and thus accelerate wear of components. We have recently published details on these interrelationships in [22]. Typical places where short-wave irregularities occur are welds, isolated rail joints and rail defects. Due to the design of turnouts, several of these locations are present. Since turnouts of this size are usually transported as three pre-assembled panels that must be welded together on site, at least 14 joints are required (including both branches). Some of these joints are designed as insulated rail joints, essential for the train operation system. As the contact conditions between rail and wheel are disturbed by various influences, rail defects are also more likely to occur in the turnout area. Attention should therefore be paid to uneven rail surfaces when it comes to the overall understanding of quality behaviour.  
For the evaluation of short-wave effects and their impact on track deterioration, we use the rail surface signal and axle-box accelerations, both measured with OBB's measuring car. The rail surface measurement system measures irregularities in the middle of the rail head in a wavelength range of 20-1000 mm. Further details on this measurement can be found in [1]. Figure 4b shows a filtered version of the rail surface signal for turnout T_R4F_21. Several effects can be observed in the signal, and labels have been added for clarity. An isolated rail joint (1), several welds (2) and the crossing nose (3) lead to considerable irregularities of the rail surface. Deflection (4) can be assigned to a rail defect. Deflection (5) is a measurement error given in every turnout and is caused by the transition between tongue rail and switch rail and should not be considered as an irregularity of the surface. Rail surface irregularities are one of the causes of vehicle reactions. Axle-box accelerations can be used to quantify vehicle reactions. Figure 4c therefore illustrates axle-box accelerations of the measuring car. It can be clearly seen that any irregularity of the rail results in vertical accelerations of the wheels. We point out that the raw data of axle-box acceleration, which would have far more high-frequency components, is not stored on the measuring vehicle. An analysis process is performed on the vehicle to detect corrugations, resulting in the signal used here. While raw data would allow more analysis in many respects, the processed signal can still be used to quantify vehicle responses. For turnout T_R4F_21, the strongest vehicle reaction is caused by the frog and by insulated rail joints.
## 3 Results and Discussion
### Population Differentiation and Structure
Using population membership as an informative prior (i.e., with the LOCPRIOR option), the highest likelihood of the data (\(ln\) P(X 1 K) = \(-\)4442.3) was obtained at K = 2, while the highest average likelihood (\(-\)4454.18) was obtained at K = 1 (Figure S1B). Similarly, to the previous analysis, the highest \(\Delta\)K values were observed for K = 5 (1.22), followed by that of K = 4 (1.10), but this led to results without clear biological interpretation, as shown in Figure S2B. At K = 2, 76 out of 101 individuals were assigned to cluster C1 with membership probabilities greater than 75%, while a single individual was assigned to cluster C2 (Q \(>\) 0.75) and the rest would be considered \"mixed\" (Q \(<\) 0.75). In all cases from K = 3 to K = 11, no individual  
Figure 2: Factorial correspondence analysis plot showing the genetic relationships among wild hop samples (\(n\) = 101) from eight populations in Croatia. Each individual genotype is indicated by a small symbol, while population barycenters are represented by larger ones. was assigned to a cluster with membership probabilities greater than 75% (Figure S2B). The correlation between the matrices of genetic (\(F_{ST}/(1-F_{ST})\) ratios) and geographic (\(ln(\text{km})\)) distances was moderate but not significant (\(r=0.352\); \(p=0\). 105) (Figure S3). Therefore, no isolation by distance could be detected, confirming once again the extensive gene flow among populations. In contrast to our results, other studies dealing with wild hop accession showed the existence of strong structuring. [PERSON] et al. [37] detected five distinct hop gene pools in Central Italy and significant isolation by distance, which also revealed genetic structure between geographically close populations. Five genetic clusters were also identified by [PERSON] et al. [38], but the grouping of hop genotypes did not correspond to their geographical origin. On a large geographical scale, several studies showed clustering of hop accessions that partially coincided with their geographic origin. In the study that included wild hop accessions from Canada, the Caucasus, Europe, and North America, [PERSON] et al. [36] identified two main clusters corresponding to their geographical origin: North American and Euroasian, the latter being further subdivided into two subgroups, the first of which included wild genotypes from continental Europe and the second from the Caucasus region, confirming the results of [PERSON] et al. [35]. However, no relationship was found between the clustering of the European hop genotypes and their geographical origin, as was the case for the Caucasian wild populations, confirming the overlapping variability in the European wild accessions and the close genetic relationship. The same results were obtained in this study, but on a smaller geographical scale.
# Uncertainties in the Seismic Assessment of Historical Masonry Buildings
## 2 Case Studies
### Material and Modelling Parameters  
A total of 11 material and modelling parameters were selected to perform the uncertainty analysis. The material parameters of masonry were the following: \(E_{m}\), modulus of elasticity; \(G_{m}\), shear modulus; \(f_{cm}\), compressive strength; \(\mu_{m}\) and \(c_{m}\), friction coefficient and cohesion of masonry, respectively. No in situ tests had been performed. For this reason, median values were chosen based on the experimental campaigns performed on masonry of a similar typology as described previously [18; 19; 20; 21] and were applied to all piers and spandrels, i.e., any spatial variability in masonry material properties was not considered. The floor stiffness factor (\(k_{floor}\)) multiplied the default stiffness values of the flexible floor diaphragm, which were computed as: \(E_{1}=10\) GPa, \(E_{2}=0.5\) GPa, and \(G=10\) MPa according to previous work of [PERSON] et al. [22; 23]. The wall-to-wall connection factor \(\mathrm{f}_{w}\) multiplied the default wall-to-wall connection strength. This default wall-to-wall connection strength was calculated according to [PERSON] et al. [24]. The floor-to-wall friction coefficient \(\mu_{f-w}\) was directly applied to the frictional floor-wall connection, with the mean value based on the work of [PERSON] et al. [25]. The drift capacities in flexure and shear, \(\delta_{c,flexure}\) and \(\delta_{c,shear}\), are the limit collapse flexural and shear drifts at which the lateral stiffness of the macroelement is set to zero, chosen according to [PERSON] et al. [26]. An initial stiffness and mass proportional Rayleigh damping model was applied. The damping ratio was also a parameter that was considered uncertain. For each set of parameters, the modal properties were calculated first and then the Rayleigh damping model parameters were computed such that the damping ratios at the first and sixth mode corresponded to the damping ratio of this set of parameters. All parameters were assigned normal or lognormal distributions for the LHS, as shown in Table 1.  
Additionally, correlation coefficients were imposed between parameters that are often correlated in experimental campaigns to avoid generating unrealistic data sets, i.e., with the lower-bound value for modulus of elasticity and the upper-bound value for the compressive strength. Imposed correlation coefficients are shown in Table 2. A strong correlation was imposed between the modulus of elasticity, shear modulus and compressive strength. A moderate correlation was imposed between collapse drift values in flexure and shear for masonry elements. It should be noted that the imposed correlation coefficients between the parameters were only estimated based on engineering judgment.
## 4 Discussion
### Implications of Susceptibility Maps  
The susceptibility maps, created through weighted overlay analysis of factors such as DEM and land cover ([PERSON] et al., 2006 [19]; [PERSON], 2006 [29]), provide essential tools for identifying areas prone to floods and rockfalls. These maps are instrumental for targeted risk mitigation and infrastructure planning. However, it is crucial to note that susceptibility maps represent potential hazards and do not guarantee the occurrence of events ([PERSON] et al., 2014 [30]). They should be used as part of a broader risk management strategy, considering other factors such as historical data and real-time monitoring.
# IoT Sensor Challenges for Geothermal Energy Installations Monitoring: A Survey
## 2 Sensor Technologies
### Flow Rate Measurement  
The measurement of liquid and gaseous flow rates in underground geothermal structures is performed to manage and control various processes [1]. Flow rate measurement in geothermal structures applies techniques that differ in complexity, cost and the capability to perform real-time surveys. Table 3 summarizes the differences between individual methods of flow rate measurement on the basis of four attributes: the ability to provide real-time measurements (real-time), the operational status of the underground structure (out of operation), direct contact between the medium and the sensing device (direct contact) and a list of the types of underground structures where the flow rate measurement method is used (application location).  
In summary, each method, except for the calorimeter and tracer dilution, provides real-time measurements. The calorimeter and lip pressure are the only two methods used in decommissioned underground structures. Each method, except for compression load cells and the ultrasonic meter, has direct contact with the sensing medium. The application location includes geothermal power plants, open Venturi channels, geothermal pipelines and geothermal wells.  
Flow rate measurement can apply single flow rate methods or hybrid flow rate methods. Hybrid methods combine two basic methods to reduce any deficiencies that single methods may introduce. Hybrid techniques are frequently used to measure two-phase fluid flow. The following subsections describe the individual methods listed in Table 3 for flow rate measurement and estimation.  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Method** & **Real-Time** & **Out of Operation** & **Direct Contact** & **Application Location** \\ \hline Ultrasonic meter & Yes & No & No & Geothermal power plant [27], \\  & & & open Venturi channel [28] \\ Calorimeter & No & Yes & Yes & Geothermal well [29] \\ Sharp-edge orifice plate & Yes & No & Yes & Geothermal well [1,2] \\ Tracer dilution & No & No & Yes & Geothermal well [30,31] \\ Lip pressure & Yes & Yes & Yes & Geothermal well [32] \\ Venturi tube & Yes & No & Yes & Geothermal power plant [33] \\ Coriolis flow meter & Yes & No & Yes & Open Venturi channel [28] \\ Compression load cells & Yes & No & No & Geothermal pipeline [35], geothermal well [35] \\ Separator with orifice plate and silencer & Yes & No & Yes & Geothermal well [1] \\ \hline \hline \end{tabular}
\end{table}
Table 3: Summary of methods for measuring flow rate in underground geothermal structures.
###### Abstract  
Multi-Key Fully Homomorphic Encryption (MKFHE) offers a powerful solution for secure multi-party computations, where data encrypted under different keys can be jointly computed without decryption. However, existing MKFHE schemes still face challenges such as large parameter sizes, inefficient evaluation key generation, complex homomorphic multiplication processes, and limited scalability in multi-hop scenarios. In this paper, we propose an enhanced multi-hop MKFHE scheme based on the Brakerski-Gentry-Vaikuntanathan (BGV) framework. Our approach eliminates the need for an auxiliary Gentry-Sahai-Waters (GSW)-type scheme, simplifying the design and significantly reducing the public key size. We propose novel algorithms for evaluation key generation and key switching that simplify the computation while allowing each party to independently precompute and share its evaluation keys, thereby reducing both computational overhead and storage costs. Additionally, we combine the tensor product and key switching processes through homomorphic gadget decomposition, developing a new homomorphic multiplication algorithm and achieving linear complexity with respect to the number of parties. Furthermore, by leveraging the Polynomial Chinese Remainder Theorem (Polynomial CRT), we design a ciphertext packing technique that transforms our BGV-type MKFHE scheme into a batched scheme with improved amortized performance. Our schemes feature stronger multi-hop properties and operate without requiring a predefined maximum number of parties, offering enhanced flexibility and scalability compared to existing similar schemes.  
fullly homomorphic encryption; ring learning with errors; multi-key ciphertexts; secure multi-party computation Article