esa-sceva/satcom-chunk-collection huggingface dataset:
# SIC-Free Based Indoor Two-User NOMA-VLCP System
## 1 Introduction
Most of the research aims to reduce EP and improve the quality of VLC transmissions, but the VLCP system based on the NOMA structure has not yet been proposed. Recently, techniques based on time difference of arrival (TDOA), angle of arrival (AOA), and received signal strength (RSS) have been proposed to achieve visible light positioning (VLP) [17; 18; 19; 20]. Meanwhile, to support multi-user positioning services within an integrated system, an indoor VLP system based on code division multiple access (CDMA) and optical orthogonal codes (OOC) was proposed to enhance communication performance [21; 22]. To fulfill the VLC and VLP functions simultaneously, the positioning subcarrier and the communication subcarrier were used for communication and positioning respectively to build an orthogonal frequency division multiple access (OFDMA) based VLCP system [23; 24]. To avoid signal interference without disrupting the existing VLC protocol, the mode of inserting an optically detected spreading plug-in based on the VLC frame structure was proposed [25]. In order to solve the problem of resource competition in the integrated communication and positioning system, a multi-scale non-orthogonal multiple access waveform and a novel communication and positioning performance constrained positioning power allocation algorithm was proposed [26]. In order to improve the positioning accuracy in the absence of line-of-sight (LOS) signal loss and focus on the visible light positioning system based on intelligent reflective surface(IRS), the Cramer lower bound (CRLB) expression and maximum likelihood (ML) estimator applicable and an optimization adjustment method were proposed [27]. However, resource competition and overall system performance degradation could occur in VLCP systems due to the scheme of adding additional positioning signals. In recent years, researchers have studied a variety of VLP systems for different application scenarios, but the NOMA-VLP system has not yet been proposed. To address the above problems, this letter proposes a dual-user VLCP system based on baseband NOMA. The main contributions of this letter are summarized as follows: (1) A baseband NOMA-VLCP system without extra positioning power is proposed to solve the problem of resource competition between communication and positioning services; (2) A joint optimization function including the communication performance and positioning accuracy is designed to improve the system transmission and positioning performance; (3) The performance of the proposed system is analyzed and verified in simulation. The letter is organized as follows: Section 2 presents the proposed system model, Section 3 presents the simulation and experimental results and Section 4 concludes the letter.
## 2 Materials and Methods  
### Materials  
AOT, with purity >97 wt%, was purchased from Sigma-Aldrich (St. Louis, MO, United States). PEG of molecular weights 600 g/mol (Merck KGaA, >99 wt%), 1000 g/mol (Sigma Aldrich, >99 wt%), and 2000 g/mol (Sigma Aldrich, >99 wt%) were used as polymers. Prior to characterization and use, surfactant and polymers were purified under high vacuum (absolute pressure lower than 1 Pa) while heated at moderate temperature (343-373 K) to eliminate water and other volatile impurities. Residual water content was determined by Karl-Fischer titration in a Metrohm 899 coulometer. Solid materials were solubilized in ethanol and their water content was corrected according to the water content of the solvent. The chemical identity of all compounds was confirmed by \({}^{1}\)H NMR spectroscopy in a Varian Mercury 300 spectrometer, using dimethylsulfoxide-d6 (Sigma Aldrich, purity >99 wt%, deuteration degree 99.5%) as deuterated solvent. The obtained NMR spectra were processed with the MestRe-C software and are shown in the Supplementary Materials.  
Brine solutions were prepared by dissolving different amounts of sodium chloride (NaCl) in distilled water. Crude oil, with the properties listed in Table 1, was kindly supplied by Repsol (refinery of A Coruna, Spain).  
Sandstone cores used in adsorption and core flooding tests were composed of 86.47 wt% of silica and 7.31 wt% of alumina, with traces of inorganic oxides. Cores were supplied by Vinci Technologies.
# A Simple Unsupervised Knowledge-Free Domain Adaptation for Speaker Recognition
## 2 Related Work
### Embedding Adaptation  
Some previous studies have proposed adaptation methods in the embedding space. [PERSON] et al. [30] employed a linear transform to align the covariance of the target domain with the source domain and then used the transform to convert source-domain embeddings to the target domain to facilitate PLDA training. [PERSON] et al. [31] proposed to align speaker embeddings from different domains in the latent space derived from auto-encoders, and the alignment is based on the MMD criterion. [PERSON] et al. [44] presented a deep normalization approach that regulates speaker embeddings to linear Gaussians using a normalization flow model. The regulated embeddings exhibit better robustness, but not specifically for solving the domain mismatch problem. [PERSON] et al. [45] also designed a linear transform to mitigate domain mismatch, although the mismatch in their study is between enrollment and test, rather than training and deployment.  
The proposed C-LDA approach belongs to the 'embedding adaptation' category. Unlike previous studies that try to transform to [30] or align with [31] the source domain, C-LDA is self-contained: it does not use any information from the source domain. Instead, it only utilizes the clustering structure of the embeddings in the target domain and normalizes the embeddings according to this structure.
# IoTBystander: A Non-Intrusive Dual-Channel-Based Smart Home Security Monitoring Framework
## 7 Experimental Results
### Effectiveness of IoTBystander
#### 7.2.3 Performance of Dual-Channel Monitoring  
The dual-channel monitoring approach, which combines TER and AER through the dual-channel aggregation component, demonstrates consistently high performance across all types of events, including those with which TER or AER alone struggle (as shown in the DCA columns in Table 8). For events generated by dumb devices, the dual-channel approach maintains high scores similar to those of AER alone, benefiting from AER's strength in recognizing sounds while compensating for the scenarios where TER's traffic analysis alone was insufficient. Taking advantage of both channels, IoTBystander consistently delivers superior recognition performance for events from both smart and dumb devices, obtaining a broader scope of monitoring and providing context-richer input for security-oriented decision-making. Higher precision and recall demonstrate that IoTBystander reduces false positives or missed detections.  
We conducted a comparative experiment to evaluate IoTBystander against existing methods. Since prior methods do not utilize both audio and traffic channels for event recognition, we compared IoTBystander with two representative approaches: IoTAudMon [12], which relies solely on audio, and PingPong [58], which relies on network traffic. The comparative results, shown in Figure 8, highlight several key findings. IoTBystander achieves comparable performance to PingPong in monitoring smart devices, with precision, recall, and F1-scores of 0.9375, 0.9375, and 0.9375, respectively. Similarly, it performs on par with IoTAudMon in monitoring dumb devices, with precision of 0.955, recall of 0.9583, and F1-score of 0.965. However, IoTBystander consistently outperforms both methods in scenarios involving both smart and dumb devices. Specifically, it achieves a significant improvement in precision (0.948 vs. 0.6215 vs. 0.375), recall (0.9499 vs. 0.6234 vs. 0.375), and F1-score (0.954 vs. 0.6275 vs. 0.375) when monitoring a mixed environment. These results clearly demonstrate the advantages of combining both audio and traffic channels. By integrating these two sources of data, IoTBystander not only enhances overall event detection accuracy but also shows greater robustness and adaptability in multi-device environments, where traditional single-channel methods struggle.
## 3 Calculation of Gas Permeability  
After measuring the gas flow rate during the test, a series of calculations are required to obtain the gas permeability of the soil specimen. Assuming the gas flow follows [PERSON]'s law, the experimentally derived equation for the one-dimensional gas flow through the soil specimen is as follows:  
\[v_{a}=-k_{a}A\frac{dh}{dl} \tag{5}\]  
where \(k_{a}\) is the gas coefficient of permeability, \(A\) is the cross-section area, and \(dh/dl\) is the gas pressure head gradient. \(k_{a}\) varies with properties of gas. In order to avoid the effect of gas properties on \(k_{a}\), intrinsic permeability, \(K\), is constant for a given pore structure [53]. The relationship between \(K\) and \(k_{a}\) is  
\[k_{a}=\frac{\wp_{a}}{\mu}K \tag{6}\]  
where \(\rho_{a}\) is gas density; \(\mu\) is dynamic viscosity. Combining Equations (5) and (6), the following generalized equation can be obtained:  
\[v_{a}=-\frac{K}{\mu}A\frac{dP}{dl} \tag{7}\]  
Figure 5: Calibration of (**a**) differential pressure transducer for gas supply equipment; (**b**) temperature sensor and (**c**) tensiometer.  
where \(dP/dl\) is the gas pressure gradient. In the soil specimen, \(v_{a}\) is not constant due to gas compressibility and pressure gradient. For the test, the pressure gradient is constant (steady state). Then, Equation (9) can be derived from Equation (8) as follows:  
\[\mu v_{a}Pdl=-KAPdP \tag{8}\]  
Integrate Equation (9) to obtain:  
\[\mu v_{aB}P_{B}L=KA\frac{P_{A}^{2}-P_{B}^{2}}{2} \tag{9}\]  
where \(v_{aB}\) is the outlet gas flow rate, \(P_{B}\) is outlet pressure, and \(P_{A}\) is inlet pressure. For each test, the temperature T is constant and Equation (10) can be simplified as  
\[v_{aA}P_{A}=v_{aB}P_{B}=\frac{K}{\mu}A\frac{P_{A}^{2}-P_{B}^{2}}{2L} \tag{10}\]  
where \(v_{aA}\) is the inlet gas flow rate. Therefore, \(K\) can be calculated using Equation (11).  
\[K=v_{aA}P_{A}\frac{2\mu L}{A\left(P_{A}^{2}-P_{B}^{2}\right)} \tag{11}\]  
It should be noted that the proposed method for calculating the intrinsic permeability is improved from the method by [PERSON] [47]. In this paper, the gas volume varying with its pressure is considered.
## 2 Experiment Description
### Measuring Equipment
#### 2.2.3 Vibration Measurement System  
Vibration measurements were realized by the Kistler LabAmp 5165A, a 4-channel universal laboratory charge amplifier used for dynamic signals or mechanical quantities measurements with piezoelectric sensors, Piezotron sensors (IEPE) or sensors with voltage output [46]. In the case of this tests, the measurements were conducted by K-Shear 8702B500 accelerometers coupled with the amplifier. Sensors have an extended range of measurement (\(\pm\)50-500 g).
## 2 Method
### Improvements and Training of the SegFormer Network
#### 2.1.3 Improvements to SegFormer  
While the SegFormer model performs feature fusion across different scales, the fusion process might not adequately account for differences between these features in certain scenarios, leading to suboptimal performance. The SegFormer model utilizes the hierarchical Transformer decoder and the lightweight ALL-MLP decoder in the decoder module for fusing features at different scales. Although these methods theoretically capture the relationship between features at different scales, in practice, the model's design and parameter settings may not fully address the distinctions between these features.  
The hierarchical Transformer decoder is employed to model features at different scales, but the Transformer module may not effectively handle spatial differences in some cases. Additionally, the lightweight ALL-MLP decoder may not adequately distinguish the importance of features from different scales during the feature fusion process. In the instance segmentation of the rock CT images, although the original model incorporates self-attention processing and feature concatenation, it still falls short in fully considering the differences between features of different scales. For instance, the self-attention mechanism may average some spatial information instead of weighting it according to the scale differences. Furthermore, the feature concatenation process may not accurately discern the contributions of features from different scales.  
To address the issue of overlooking feature differences when directly concatenating features of different scales and to achieve bidirectional fusion between these two types of features, we have designed the module illustrated in Figure 4.  
Firstly, two hierarchical features are inputted, as shown in Figure 5. The symbols 1, 2, 3, and 4 represent the feature maps of different scales, which are illustrated in Figure 5. When 1 is used as the high input, 2 becomes the low input. Both features pass through the conv module to adjust their channel numbers. The low feature undergoes a sigmoid activation and is then multiplied elementwise with the high feature, aiming to enhance edge information. The resulting feature is then combined with the low feature to obtain richer semantic information. The high feature is also passed through a sigmoid activation and multiplied elementwise with the previous feature to enhance attention towards the region of interest. Finally, the resulting feature is added to the high feature to obtain the output. This achieves bidirectional fusion. The output is used as the high feature, while 3 is used as the low feature, repeating the aforementioned process. Ultimately, the features are combined at each level, fully utilizing features of different scales. Essentially, we integrate features at various levels. Initially, 1 and 2 are fused, and the outcome is  
Figure 4: The implementation method of feature fusion.  
subsequently combined with 3. The resulting output is then further integrated with 3, completing the entire feature-splicing process.
## 1 Introduction
In this latter case, the intensity of the effect seemed to be somewhat dependent on the length of the water curing period [14]. However, the same authors found that the difference in total charge passed (coulombs) in the rapid chloride permeability (RCP) test [18] between concrete mixes with and without CA was inconsistent [14]. Recently, a study [19] has reported a reduction in the Cl\({}^{-}\) diffusion coefficient (obtained through a Cl\({}^{-}\) migration test [20]) when incorporating a CA to two concretes prepared with a CEM II-type cement [21]. Very few publications [16; 19] have addressed the effect of CA on the corrosion of steel reinforcement embedded in concrete. Both mentioned articles have concluded that the incorporation of CAs to reinforced concrete specimens can delay the onset of the steel corrosion [16; 19]. The objective of this work is to perform a preliminary study of the effect of a commercial CA on selected durability-related properties of reinforced Portland cement concrete: some parameters related to the micro-structure (permeable porosity and electrical resistivity of water-saturated specimens) and some key mass transport parameters (Cl\({}^{-}\) diffusion coefficient obtained through a natural diffusion test procedure, water absorption coefficient through [PERSON]'s test [22], and air permeability of concrete through [PERSON]'s test [23]). Finally, some preliminary tests have been performed on the corrosion of embedded steel into concrete specimens containing the CA. The corrosion behavior has been assessed through classical non-destructive electrochemical techniques. The same CA has been previously found to provide concrete with considerable resistance to water penetration under pressure [11] and to capillarity water absorption [24]. Although an air permeability test has been used before to assess the ability of concrete mixes (containing several additives including a commercial CA) to self-healing pre-cracked specimens [25], to the best of the authors' knowledge, no previous publication has studied the effect of an integral CA on the air permeability of bulk uncracked concrete. Hence, this study might be the first to address the CA-mediated possible reduction in the air permeability of concrete, which can play a role on determining the corrosion rate of steel reinforcement. It can be also an important property to be considered in certain applications such are concrete enclosures of nuclear facilities or underground concrete walls in contact with the terrain, which can be susceptible to be permeated by radioactive radon gas.
# Maximizing Efficiency in Energy Trading Operations through IoT-Integrated Digital Twins
## 2 Related Work
The objective was to optimize the trade-off between secrecy and energy efficiency, taking into account the presence of imperfect angles of departure. This study presented two resilient beamforming strategies for both single and multiple earth stations, showcasing their efficacy through simulations utilizing realistic channel models. Similarly, the study [35] centered on the augmentation of security and energy efficiency in multibeam satellite systems through the optimization of system secrecy and energy efficiency while adhering to a total power constraint. The nonconvex issue was decomposed into subproblems using an alternating optimization strategy, which incorporated the signal-to-leakage-plus-noise ratio and consecutive convex approximation techniques. The simulations provided evidence of the higher performance of the proposed strategy compared to benchmark alternatives in terms of security and energy efficiency. Another study [36] examined the issues associated with IoT connectivity and proposed a solution by exploring the concept of rate-splitting multiple access (RSMA) within a satellite and aerial-integrated network (SAIN). This study aimed to enhance multicast communication for Internet of Things devices (IoTDs) in a content delivery context, with a specific focus on mitigating interference and improving spectral efficiency. The RSMA approach, as suggested, was guided by an iterative optimization algorithm. This method significantly improved the sum rate of the system and reduced mutual interference. It was shown to outperform benchmark schemes in the context of IoT applications. This study centered on enhancing communication efficiency inside a satellite-terrestrial-integrated network (STIN) by utilizing non-orthogonal multiple access (NOMA). The study [37] proposed a novel approach combining beamforming and power allocation techniques to optimize the overall data transmission rate while ensuring adherence to quality-of-service requirements and power limitations for both satellite and cellular users. The suggested methodology, incorporating a unique user pairing scheme and utilizing an iterative penalty function-based beamforming technique, demonstrated superior performance compared to current approaches. This advancement held promising advantages for the field of Internet of Things (IoT) communication within integrated networks. The existing studies are delineated in Table 1.  
Based on a critical analysis of the existing studies, the proposed study aims to leverage IoT technology and digital twin-based methods to transition traditional smart grids into IoT-based frameworks for more efficient energy resource sharing. It covers advantages like enhanced energy trading efficiency and reduced expenses through optimization techniques. The study addresses the untapped potential of IoT in the energy sector, particularly in improving energy resource sharing and overall system performance.
## 1 Introduction
Conversely, the output of renewable resources, especially the fluctuation of PV generators and wind turbines, depend on environmental conditions that result in power-supply instability. Thus, providing stable power by renewable generators is the main challenge when producing consistent electrical networks. Consequently, renewable generators need to be combined with energy storage systems to solve instability problems. Additionally, PV modules and the related power electronic converters as a small-scale DC system impact on the system's operation in any short-circuit situation [10]. Also, converters can lose their controllability to retain the bus voltage within acceptable values. Due to the low DC impedance and rapid increase of the fault current, the DC network needs a high-speed protection system, which has significantly different requirements compared to an AC fault protection system. Fault area isolation from the rest of a DC grid would provide safety for the operation of non-faulted areas [11; 12]. Furthermore, the application of traditional low-voltage (LV) AC protection solutions for a DC microgrid has the drawback of slow operation, resulting in the requirement for electrical components with a higher capacity (which cause a high initial cost and take up more space) [13]. Besides, battery banks or capacitors would feed the short-circuit current, resulting in a lot of thermal and mechanical stress on the system's components [14]. To overcome this challenge in direct current systems, a high-speed protection system with an appropriate circuit breaker (CB) is a known exigence [15]. Due to the absence of mechanical components, contact erosion, having a long lifetime and high-speed operation (tens of microseconds (\(\upmu\)s)), the semiconductor breakers are considered as a potential solution to overcome these barriers in a DC system [16; 17]. In this study, we analyse a short-circuit protection scheme based on semiconductor technologies. For the protection of the entire network, an ideal two-way semiconductor Solid State Circuit Breaker(SSCB), based on IGBT and a control system are used to detect the fault current, and we isolated it in any part of the system within a short time. The rest of the paper is organized as follows: Section 2 deals with the structure of the proposed DC microgrid schemes and components design. The DC fault characteristics and effects are explained in Section 3. In Sections 4 and 5, different fault-detection methods and the proposed methodology are introduced. The results and discussion are presented in Sections 6 and 7. Finally, the study is concluded with the main findings and contributions in Section 8.