esa-sceva/satcom-chunk-collection huggingface dataset:
# Energy-Efficient Clustering Multi-Hop Routing Protocol in a UWSN
###### Abstract
* Three types of node: cluster head (CH), cluster member (CM), and cluster relay (CR). If a node is the cluster head, the role of the node can be an aggregation node. If a node is the cluster relay, the node forwards data from two clusters at two depth levels. Otherwise, nodes are designated as a cluster member and only send data to the cluster head. * The underwater sensors calculate the weight according to the node's depth and residual energy to elect to become the cluster head. * The routing protocol takes into account the number of cluster members and load balancing parameters so that the node selects the best route to the destination. The remainder of the paper is organized as follows: Section 2 reviews the existing clustering routing protocols for UWSNs; Section 3 introduces and analyzes the energy-efficient clustering multi-hop routing protocol; Section 4 presents an evaluation of network performance in comparison to the LEACH protocol and DBR routing protocol; Section 5 concludes the paper.
## 4 Experimental Results
### Classification Performance of the HSAN  
Table 6 presents the average results obtained for three evaluation metrics of the HSAN under each severity label. In summary, for the validation set, the \(PRE_{overall}\), \(REC_{overall}\), and \(F1_{overall}\) values of the HSAN were 64.16%, 61.62, and 62.46%, respectively; for the test set, the \(PRE_{overall}\), \(REC_{overall}\), and \(F1_{overall}\) values of the HSAN were 61.01%, 58.32%, and 58.94%, respectively. The average recall of the \"serious\" severity label was lower than that of the other two labels, because the ratios of the samples in the training and validation sets were unbalanced. The number of samples labeled as \"serious\" constituted a larger proportion of the training set but a smaller proportion of the validation set. Therefore, the unbalanced data affected the classification performance. The aforementioned results were similar to those obtained for the validation set. The average recall of the \"serious\" severitylabel was lower than the other two labels, because the distributions of the validation and test sets were the same and the data were unbalanced.
## 3 Results and Discussion
(**d**) The results generated by the trainees were transferred on a stand-alone computer to be reviewed and discussed with the staff. number of samples, [PERSON] et al. used the same heat treatment step as in our laboratory tent to inactivate the virus [17]. Furthermore, all samples were tested by BFA within 6 days of the qPCR test, a significant difference from our time interval, which was up to 46 days [17]. However, a complete validation of the BFA test was not within the scope of the current study. Instead, we evaluated the user-friendly and biosafety features of fast, automated assays, using the BFA test as an example. The focus of the JiTT program was on hands-on testing and training of local non-expert collaborators with the aim of enhancing their expertise in laboratory practices and infectious disease diagnostics for future missions in their own country and other African countries, thus contributing, if only on a modest scale, to national capacity building in terms of individual laboratory competence. Post-training evaluations and contacts were organised to assess the evolution and technical skills gained by the two researchers during the B-LiFE mission. To begin, we invited the two researchers to spend a week in our laboratory in Belgium a few months after the mission, depending on their availability. One of the researchers ([PERSON]) visited Belgium and worked in our laboratory for a week. We went over all of the molecular diagnosis procedures and techniques with him this week, allowing him to build on his knowledge from his participation in the JiTT in N'Zerckore. We also conducted one-year phone interviews with both biologists to assess their career development and participation in other similar missions in their country, specifically, and in Africa in general. These interviews revealed that [PERSON]'s JiTT B-LiFE training enabled him to be hired by MSF Belgium/France. The second biologist ([PERSON]) was appointed director of Guinea's haemorrhagic fever laboratory, N'Zerekore. Rather than issuing a certificate of attendance in the future, it would be more useful to issue a certificate of technical competence, which could be more meaningful since this reflects the level of technical competence and the acquisition of essential quality assurance and biosafety principles.
# Wind Pressure Coefficient on a Multi-Storey Building with External Shading Louvers
## 4 Results and Discussion
### Features of Local Wind Pressure Coefficient along Measurement Lines
#### 4.2.3 Local Wind Pressure Coefficient on R-S Lines  
Figure 14a-f presents the local range \(R\), local and average value of wind pressure coefficient \(C_{\text{P}}\), on the central lines of R3-R5, along the roof and leeward surfaces. The \(C_{\text{P}}\) distributions along R-S lines are obviously smoother than \(C_{\text{P}}\) along W-R-L and W-S-L lines, because only the windward surface undergoes positive wind pressure. Generally, The \(R\) has the largest value on the central lines of R3, while \(R\) has the smallest value on the central lines of R4. The result indicates that R4 on the lateral surface seems to be the transitional zone, where the impact of reverse flow becomes weaker, so the presence of shading louvers cannot change \(C_{\text{P}}\) greatly. On the three lines, most local \(R\) on the roof is larger than those on the lateral surface. The maximum \(C_{\text{P}}\) locates on the lateral surface near the ground for the central lines of R3 but on the roof for the central lines of R4 and R5. The minimum \(C_{\text{P}}\) locates on the roof for the central lines of R3 and R4 and on the lateral surface for the central lines of R5. The largest \(R\) locates at \(0h_{0}\) for the central lines of R3 and R5 and at around \(0.48h_{0}\) near the edge between the roof and lateral surfaces for the central lines of R4. The \(R\) changes strongly along the central lines of R3 but more slightly along other two lines. The result of R3 means that the reverse flow near the roof and the lateral surface are both sensitive to the shaded conditions.
## 2 Related Works
The amount of RIS elements increases the attainable rate, with PSO-based optimization outperforming random phase selection. The channel state information (CSI) is essential for RIS to function accurately. RIS-based systems exhibit high sensitivity to CSI errors. The foundational premise of the RIS concept relies on the assumption that RIS elements have complete knowledge of the channels connecting the BS to RIS and from RIS to UE. With this channel information, the RIS can effectively execute both the pre-compensation and post-compensation phases of the channel. However, if the CSI is imperfect, the optimal phase shifts that each RIS element should introduce will be inaccurate. This inaccuracy can compromise the joint beamforming process between the transmitter and the RIS, subsequently hindering the realization of the advantages associated with RIS technology. Deep learning techniques based on compressive sensing are suggested in [53] to estimate channels in RIS-assisted mmWave MIMO systems with limited training overhead. The recommended method takes advantage of joint sparsity in angles and among subcarriers. This proposed work aims to assess the ABER and sum rate performances of the assisted mmWave M-MIMO system under the considered channel models and frequencies for different transmit antenna and RIS configurations.
# LED Nonlinearity Estimation and Compensation in VLC Systems Using Probabilistic Bayesian Learning
## 6 Conclusions  
In this paper, we have proposed a novel LED nonlinearity estimation and compensation scheme based on PBL regression for OFDM-based nonlinear VLC systems. The performance of the proposed PBL-based scheme has been evaluated by numerical simulations and further compared with the conventional TDA scheme. The obtained simulation results have shown that the proposed PBL-based scheme can accurately estimate the nonlinear power-current curve of the LED and hence efficiently compensate the adverse effect of LED nonlinearity. More specifically, the proposed PBL-based scheme with a single TS can achieve a comparable BER performance as the conventional TDA scheme with totally 20 TSs. Therefore, the required training overhead for LED nonlinearity mitigation can be substantially reduced and the overall system spectral efficiency can be greatly improved by adopting the proposed PBL-based scheme. It is also shown that the proposed PBL-based LED nonlinearity estimation and compensation scheme is computational efficient, which is suitable for potential application in practical VLC systems.  
Conceptualization, C.C., X.D., Y.Y. and L.Z.; Formal analysis, C.C., X.D., Y.Y. and H.Y.; Funding acquisition, C.C.; Project administration, C.C. and P.D.; Writing--original draft, C.C. and P.D.; Writing--review & editing, C.C., X.D., Y.Y., P.D., H.Y. and L.Z.  
This research was funded by the Starting Research Fund from the Chongqing University (No. 02140011044110).  
Figure 7: BER vs. MI without and with LED nonlinearity compensation.
## 2 Methodology and Data
### Proposed Forecasting Framework  
#### 2.1.1 Multilayer Perceptron (MLP)  
In this paper, we embark on developing a novel type of NAR neural network, which can be categorized as a specific case of the widely studied multilayer perceptron (MLP) neural networks. MLPs, belonging to the feedforward neural network family, exhibit a distinct structure consisting of an input layer, an output layer, and one or more hidden layers sandwiched in between (see Figure 1). Each layer comprises a set of nodes or neurons that contribute to the network's overall computational capabilities.  
One notable feature of MLP networks is their supervised nature, wherein a training set is utilized to iteratively adjust the network's parameters until it achieves an optimal fit to the provided data. This adaptation process is facilitated by a learning algorithm, and in our study, we employ the widely adopted backpropagation algorithm, which excels in regression tasks [54; 55].
## 5 Discussion
### Suitability of the Methods Used  
The MODIS 250 m remote sensing data seems to be sufficiently resolved to reveal drought patterns for different land cover types in the relatively heterogeneous landscapes of Germany, which are typical for central Europe. To date, the MODIS time series is one of the few satellite data sets allowing an assessment of vegetation condition in the long-term perspective of almost two decades with the necessary spatial and daily resolution crucial to detect highly variable phenological processes. Even the promising, higher spatial resolution Copernicus data will not allow this kind of temporal classification for some time to come. The CORINE land cover map offers sufficient spatial resolution (100 m) to differentiate between different land cover types. Focusing on the status of the vegetation enables an assessment of agricultural droughts, which are strongly connected to socio-economic factors such as agricultural yields. The usage of satellite earth observation data allows an extensive investigation without the need of interpolation or modelling. A limitation of the study approach is the difficulty in disentangling drought effects, effects from other abnormal weather conditions such as snow water availability or frosts, and management strategies. As within this study, particularly unfavorable weather conditions in spring, like snow and frosts, were easily confused with drought or heat events, so including snow cover information [58] would support a more comprehensive detection of the effects of dry and hot weather. In addition, there might be uncertainties introduced through crop rotation. An investigation on the level of different crop types might be an interesting next step, making a detailed crop type classification with high spatial resolution necessary [59]. Another important aspect is irrigation, as irrigated croplands or grasslands can distort the effects of drought on vegetation. In Germany, only 2.5% [31] of agricultural area was irrigated in 2018, so the effect can be considered as minimal. In addition, it has to be kept in mind that the approach constitutes an analysis of extreme conditions within the study period only. It is not possible to make a statement about the magnitude of the detected extreme conditions compared to the years before 2000. Regarding the crop yield data, an uncertainty is potentially introduced as the crops, considering their drought resistance, might have changed during the last 20 years. More information on the cultivation of specific crop types is needed to take this into account.
## 3 Results
### Evaluating Weather Conditioning  
Due to the auxiliary branch being trained in a supervised manner, it has to be exposed to the variety observed in the training set. As such all clips in the dataset were evenly distributed across equally-sized training, test, and validation sets. Because this potentially allows a naive approach to generalize easily, due to the inclusion of the full variation present in the dataset, the proposed method is compared to an equally trained naive approach without the auxiliary meta-prediction branch.  
To evaluate the potential impact of each of the three meta-conditions (namely, temperature, humidity, and time of day), each model was trained naively (i.e., according to the training loop described in the respective paper [2; 54]), as well as with the auxiliary conditioning branch (direct and indirect conditioning for YOLO- and DETR-variants, respectively). To allow for fair optimization, each model was trained for the same amount of epochs as their respective baseline.  
Likewise, we observed the performance when comparing the temperature and object size to investigate if any of the categories potentially suffered. This was conducted in order to reach a more general improvement of the system. While these correlations might not be intuitively tied to the weather, the latent representation learned could inadvertently favor certain aspects of the object distributions.  
Because conditions are quantified using different metrics, the ground truth ranges varied significantly. To normalize their representation, the values were remapped so that the observed values fell roughly within the range of \([-2,2]\). This range was chosen to avoid the network having to also learn a mapping between arbitrary ranges while keeping in line with the normalization that is conducted internally in the networks (which is performed to avoid unstable variances in the activations [32; 33; 50]).
## 4 Detection Methods: Derivative Spectroscopy  
MIR spectroscopy is attractive for the strong fingerprint signature, and the commonly used DAS often suffers from low selectivity for the spectra overlapping of broadband absorption. Derivative spectroscopy uses first or higher derivatives of absorbance with respect to wavelength for qualitative analysis and for quantification with higher selectivity [152]. The derivatization of zero-order spectrum can lead to separation of overlapped signals or elimination of background caused by other compounds in a sample [153; 154].  
Derivative spectra could be obtained by the Savitzky-Golay (SG) smoothing/differentiation procedure, which is widely implemented in instrumental software or in packages for spectral data processing. The resolution enhancement in the second derivative spectrum depends on the data spacing in original spectra, absorption peak profile, parameters of SG (i.e., window size and polynomial order). To maximize the separation of the peaks in a second derivative spectrum, the original spectra should be recorded at high resolution and using appropriate parameters [155]. Other methods used to calculate the derivative spectra include numerical differentiation [156] and continuous wavelet transform [157]. The latter has been proven to be efficient in the analysis of overlapping spectra and is advantageous for providing higher SNR and flexibility in searching for absorption peaks.  
Derivative spectroscopy can be used in various spectral region including UV [158], visible [159], NIR [160; 161], and MIR. The method has a close dependence on instrumental parameters, like speed of scan, the linewidth, and SNR. The derivatization can amplify the noise signals in the resulting curves, which normally leads to a higher SNR. Another disadvantage is the non-robust character of the selected parameters of the elaborated methods. The selected parameters of this method are applicable only for the studied system and every change in composition requires re-optimization and the selection of new parameters of derivatization [153]. Without a homogeneous protocol of optimization, the parameters of the method vary, and most researchers did not describe the parameter selection in their published articles.
This single-layer, dual-element FSS efficiently attenuates signals in the X- and Ku-bands while ensuring wide-angle stability up to 75\({}^{\circ}\), making it fit for selective RF shielding and isolation. Furthermore, ref. [26] introduces an FSS structure designed on both sides of a glass substrate using optically transparent conductive ITO material. The geometry incorporates a cross patch with Y-shaped branches, achieving a wide stopband. This FSS provides EMI shielding in the 5G mmW band with an insertion loss of \(-\)14 dB, high angular stability, and polarization independence, making it suitable for integration into building glass doors and windows. In [27], an FSS consisting of two coupled resonators printed on a thin dielectric is developed for 5G mm wave stopband applications at 28 GHz and 38 GHz. It attains polarization-independent filtering response with stability up to 60\({}^{\circ}\), and achieves rejection bandwidths of 42.8% at 27.3 GHz and 24.2% at 39.12 GHz, respectively. In the works reported above, many FSS designs suffer from inconsistencies in the stop bandwidth and shielding response for oblique angle variations under the TM mode. This paper investigates a miniaturized dual-polarized FSS shield designed for EMI mitigation. The FSS functions in two configurations in the X-band. It has a flower-shaped fourfold symmetrical geometry, maintaining higher angular stability and excellent shielding performance. The rest of this paper is organized as follows: Section 2 presents the design configuration and ECM of the FSS cell. Section 3 reports the simulated results, angular stability analysis, and parametric analysis. The measurement setup and measured results are discussed in Section 4. Finally, Section 5 summarizes and concludes the article.
## 3 Methodology of Complementary Filter Calibration
### Performance Evaluation of the Optimized Signal
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Roll Angle** & **MSE** & **RMSE** & **Pitch Angle** & **MSE** & **RMSE** \\ \hline
0 & 0.005352 & 0.073161 & 0 & 0.002493 & 0.049934 \\
5 & 0.003722 & 0.061010 & 5 & 0.002609 & 0.051075 \\
10 & 0.003526 & 0.059377 & 10 & 0.002682 & 0.051790 \\
15 & 0.004319 & 0.065719 & 15 & 0.002828 & 0.053177 \\
20 & 0.004270 & 0.065346 & 20 & 0.002550 & 0.050495 \\
25 & 0.003805 & 0.061685 & 25 & 0.002570 & 0.050691 \\
30 & 0.003597 & 0.059972 & 30 & 0.002725 & 0.052202 \\ \hline \end{tabular}
\end{table} 
Table 3: MSE and RMSE for observed pitch and roll angles. To provide a more comprehensive picture, it is necessary to analyze the number and duration of continuous sequences (time intervals) during which the signal exceeds the defined range. This allows for the estimation of the probability that the signal remains above or below the threshold for a specified duration, which is a multiple of 0.02 s. Recall that 0.02 s corresponds to the sampling period, and this multiple refers to the number of consecutive samples within a single uninterrupted sequence that stay above or below the threshold. For such an analysis, it is useful to include the ratio of the time spent outside the threshold to the subsequent time the signal remains within the range. This will allow us to observe whether the signal briefly returns to the range only to exit it again, and how frequently such situations occur. These two metrics enable a significantly more detailed understanding of the signal's behavior. In our experiment, after narrowing the range, we observed only sporadic continuous sequences of the signal exceeding the threshold.
## 2 Background  
The space communications industry historically approached the provision of broadband services with Geosynchronous Equatorial Orbit (GEO) satellites, ensuring service availability to user terminals thanks to their high orbital altitude that provides wide Earth visibility and a fixed position in the sky [10]. However, this also resulted in large latencies and difficulties to reach polar regions due to their orbital plane configuration situated on the equatorial axis. Despite the benefits of service availability, the elevated latency of about 120 ms (calculated by dividing the orbital altitude, 35,786 Km, by the speed of light) entailed significant performance degradation for broadband services. At present, this industry remains active for stringent use cases, such as backhaul connectivity (SES [11] and Hughes [12]) or limited Internet access (Viasat [13] and Hispasat [14]).  
Over the years, the technological trend of the broadband industry has driven increasingly stringent service requirements in terms of latency and throughput [15]. The New Space has played a key role in this scenario with the aforementioned impulse to LEO solutions aimed at meeting these requirements. Specifically, the emergence of mega-constellations has been a major achievement, as it has brought groundbreaking vision to the sector on the Internet from space. To date, several proposals for mega-constellation projects have been formalized, but only two have reached commercialization: OneWeb by Eutelsat and Starlink by SpaceX. Table 1 provides the main information related to some  
Figure 1: The 5G NTN transparent architectures proposed for this work. (**a**) Relay of the backhaul. (**b**) Relay of the midhaul. (**c**) Relay of NR.  
of these projects, including the satellite operator, a few orbital parameters such as their altitude and inclination range, the total number of satellites planned for the final phase of the project, and the number of satellites that have been launched so far. Note that these data are subject to frequent changes and can vary over short periods of time.  
The disruption of satellite broadband connectivity has also been reflected in 3 GPP with the standardization of NTN. The potential of new vertical opportunities in the market has generated multiple research topics surrounding the implementation of NTN. One such topic is the integration of the 5G functional split technology, whose goal is the disaggregation of the gNB in the CU, DU, and Radio Unit (RU) [29]. These logical modules host from the upper to the lower layers of the Uu protocol stack, respectively, and can be implemented on separate physical instances. In this way, the gNB can be spatially distributed, notably enhancing the flexibility of the network. This is an interesting approach for NTN to model the configuration of gNB deployment, both in transparent and regenerative architectures [30].