esa-sceva/satcom-chunk-collection huggingface dataset:
# A New Sum-Channel Radiating Element for a Patch-Monopole Monopulse Feed
## 3 Results  
### Scattering Parameters  
The scattering parameters were measured together with a simple feeding circuit: a coaxial sum-channel balun and a difference-channel monopole impedance-matching stub. The feeding circuit was only coarsely optimized with the conventional cut-and-try method, so only the measurements are provided in this subsection. The simulations indicated that the return loss is not a limiting factor of the design with a good feeding circuit, and confirmed that the patch impedance remains predictable [23]. The return loss frequency characteristic is shown in Figure 5. It indicates a nonideal sum-channel balun for matching the target frequency of 2.21 GHz. The crosstalk between the sum and difference channels of the measured prototype is around \(-35\) dB in the band, and is also shown in Figure 6.  
Figure 4: Patch-monopole monopulse feed final prototype during radiation-pattern measurements.  
Figure 5: Return loss frequency characteristic measurement of both channels.
## 1 Introduction  
The need for fast data rate and widely available mobile communications systems is driving the adoption of satellite communication (SATCOM) technologies. Companies such as SpaceX, Telesat, OneWeb, and Amazon are developing large low Earth orbit (LEO) mega-constellations that require ground terminals capable of tracking multiple satellites [1]. Unlike conventional satellite systems, this type of system requires a large number of gateway antennas located near or co-located with internet peering points. Phased arrays are becoming a popular solution for this purpose, offering improved directivity and the ability to electronically steer the beam and operate with multiple satellites simultaneously. This results in an improved signal-to-noise ratio (SNR) and increased directional resilience to interference [2].  
As illustrated in Figure 1, a phased array consists of a number of antennas driven by a common source and arranged to direct individual phases in a particular direction while suppressing them in others. When operating at high frequencies, the separation between the elements is reduced, resulting in a need for minimal physical space. To effectively integrate the elements in these configurations, it is essential to utilize low-cost, low-power consumption circuits. One possible solution is to use microwave integrated circuits (MMICs) in the array electronics, as they provide the required performance in a compact area.  
The key components for directing and focusing the beam in a phased array are phase shifters. These electronic devices change the phase of the elements in the antenna array to direct the main radiation beam. Phase shifters are typically implemented using vector-sum phase shifters (VSPS) or vector modulators (VM). This paper presents a novel and compact VM architecture implemented in 130 nm SiGe BiCMOS technology, suitable for use in receive phased arrays for the gateways of major LEO constellations operating in the 17.8 to 20.2 GHz frequency range. The proposed architecture uses four variable gain amplifiers (VGA) that are active at any given time and are switched to generate the four quadrants. Compared to conventional architectures, this structure is more compact and produces double the output amplitude.  
The organization of this paper is as follows. Section 2 describes the state-of-the-art and the proposed vector modulator. Section 3 presents the circuit design of the proposed vector-sum phase shifter. Section 4 shows the measurement results and Section 5 concludes this paper.
# Experimental Study of Vibration Isolation Characteristics of a Geometric Anti-Spring Isolator
## 4 Experimental Study
### Experimental Setup  
The single degree of the freedom vibration evaluation system is made up of three parts: the excitation system, the data acquisition system and the primary vibration isolation system. The excitation system is composed of the signal generator, the power amplifier, and the electro-dynamic shaker. The electro-dynamic shaker (DC-4000-40/SC-0808, Suzhou Sushi Testing Instrument Co., Ltd, Suzhou, China) can provide base excitation in the frequency range 1-2000 Hz. Its excitation maximum displacement is 38 mm. The maximum working load and output maximum acceleration are 500 kg and 100 g (1 g = 9.8 m/s\({}^{2}\)), respectively.  
Figure 8: Dynamic experimental system for the geometric anti-spring isolator. (**a**) Schematic of the dynamic experimental setup; (**b**) Photograph of the dynamic experimental setup; (**c**) Photograph of the primary vibration isolation system.  
The data acquisition system includes two piezoelectric accelerometers sticking on the load mass and the base, a charge amplifier, a dynamic data analyzer (SignalCalc ACE, Data Physics Corp., San Jose, CA, USA), and personal computers (PC, Lenovo, Beijing, China). The acceleration signals are acquired and post processed by the dynamic data analyzer to obtain the evaluation result of vibration isolation performance.  
The primary vibration isolation system is a single-degree-of-freedom system consisted of the geometric anti-spring isolator and load masses. The base is rigidly fixed on the electromagnetic vibration table. Four linear guides are connected to the base to maintain the load mass vertically translational motion through linear bushings. The geometric anti-spring isolator is installed between the base and the load mass with bolts. The load mass is composed of a big cylinder (16 kg) and several small mass blocks. The load mass ranges from 16 kg to 28 kg.
# A Survey on Blockchain-Based Federated Learning
## 4 Applications
### Industrial Internet of Things  
The IIoT encompasses an intricate network of interconnected sensors, equipment, actuators, and other intelligent components. These components facilitate adaptive decision-making and continuous status tracking [123; 124], playing a pivotal role in the digital transformation and intelligentization of the contemporary manufacturing industry. In a study conducted by [PERSON] et al. [89], BlockFed was employed to facilitate data sharing within the domain of IIoT. The data-sharing challenge was approached by framing it as an ML problem, incorporating privacy-preserving FL, and integrating FL into the consensus mechanism of a permissioned blockchain. The computational effort required for the consensus was also utilized for federated training. In the context of fault detection scenarios in IIoT, [PERSON] et al. [91] proposed a federated averaging algorithm called Centroid Distance Weighted Federated Averaging. This algorithm takes into account the distance between negative and positive classes within each client dataset, thereby mitigating the impact of data heterogeneity challenges in IIoT device fault detection. Additionally, [PERSON] et al. [92] recognized the challenges posed by unreliable communication channels, computational resource constraints, and the intricacies associated with establishing trust among users within the context of IIoT. To address these issues, they developed an FL framework for collaborative computation empowered by blockchain technology. This framework substantially elevated the system's reliability, security, and privacy.
# Analysis of SNR for High-Orbit Target Detected by Ground-Based Photoelectric System
## 6 Conclusions  
A simplified model was developed for use in predicting the SNR of a high-orbit object. The fidelity of the model was constrained by MODTRAN and the parameters of a photoelectric system. In our basic calculations, the targets were modeled as a remote black-body to evaluate their SNR. From the simulation results, shortwave infrared had high detection capability. The maximum detection range was 1.283 \(\times\) 10\({}^{4}\) km, and at an orbit of 1 \(\times\) 10\({}^{4}\) km, the minimum detection temperature was 184 K. Atmosphere has different windows, creating many transmittances and radiances at different wavelengths. From MODTRAN calculation values and parameters of the optical system, short infrared bands have better imaging effects of HOTs. The short infrared bandwidth was more sensitive to the SNR of the target, so our model can be used as a convenient and effective standard to judge whether a target can be detected. On the basis of the simulation system, we built a K-band infrared terminal camera on a large aperture optoelectronic system, and some effective observations of space targets were carried out. Obtained data from observations were few, and the obtained band was relatively simple. In future research, we will develop more infrared filters and cameras in the imaging terminal, so that more infrared bands will be taken in the large aperture optoelectronic system to obtain more data to improve this simulation model.  
[PERSON] conceived the presented idea and developed the theoretical formalism; [PERSON] and [PERSON] analysed the data; [PERSON] and [PERSON] wrote the paper.  
The authors declare no conflict of interest.
# A Linear Memory CTC-Based Algorithm for Text-to-Voice Alignment of Very Long Audio Recordings
## 2 Related Works
### CTC-Based Modeling for the Encoding Step  
In our applicative context, the timestamped encoding \(\mathcal{E}\) can be implemented as the output of a CTC-trained neural network trained on audio directly, which represents the per-frame character emission probabilities--referred to as _posteriorgram_.  
To the best of our knowledge, [PERSON] et al. [38] were the first to exploit this strategy when they explicitly leveraged the time dimension of CTC posteriorgrams to align the lyrics and singing voice with background music. By extracting multi-scale representations from raw audio samples with a Wav-U-Net architecture [41], trained on a 40k+ song proprietary dataset, the authors proved the feasibility of aligning polyphonic music with an end-to-end CTC acoustic prediction framework, and demonstrated the interest of this approach for text-to-voice alignment in general. For instance, [PERSON] et al. [39] used a CTC-based neural network originally trained for ASR purposes to segment, at the sentence level, a large corpus of German speech recordings, and demonstrated that this approach clearly outperformed HMM-based legacy methods in terms of alignment precision.  
In the same vein, and following the success of their CTC-based model in other tasks [42; 43], [PERSON] et al. [44] demonstrated that a plain Convolutional Recurrent Neural Network (CRNN) could also yield promising performances. Trained with the publicly available data contained in DALI [45], the authors tackled the issue of voice alignment in a multilingual context, even for language with almost no training data.  
More recently, [PERSON] et al. studied the impact of adding additional constraints to the CTC in order to improve the accuracy of the posteriorgrams. By combining the CTC loss with a spectral reconstruction cost in an encoder-decoder architecture [46], better synchronization precision was achieved for clean recordings featuring solo speaking and a singing voice. This precision at the phonetic level could be used to analyze the temporal aspects involved in the production strategies of vocal attitudes in expressive speech [47; 48]. Further works have proposed other types of regularizations enforcing audio-text monotony and structural similarity [49], but did not specifically focus on _long_ audio alignments, as opposed to our present work.
## 2 Theoretical Aspects  
In this section we will briefly describe some concepts at the basis of the procedure for reducing the effects of measurement noise in the identification of the Hammerstein model based on swept sine signals: The procedure for model parameters identification is first recalled, then the effect of noise on the assessment of model kernels \(h_{i}(t)\) is evaluated. Finally, the frequency bands characterizing the signals involved in the different steps of the identification procedure are analyzed.
# Coverage Optimization of WSNs Based on Enhanced Multi-Objective Salp Swarm Algorithm
###### Abstract  
In complex two-dimensional monitoring environments, how to enhance network efficiency and network lifespan while utilizing limited energy resources, and ensuring that wireless sensor networks achieve the required partial coverage of the monitoring area, are the challenges of optimizing coverage in wireless sensor networks.With the premise of ensuring connectivity in the target network area, an enhanced multi-objective salp swarm algorithm based on non-dominated sorting (EMSSA) is proposed in this paper, by jointly optimizing network coverage, node utilization, and network energy balance objectives. Firstly, the logistic chaotic mapping is used to maintain the diversity of the initial salp swarm population. Secondly, to balance global and local search capabilities, a new dynamic convergence factor is introduced. Finally, to escape local optima more effectively, a follower updating strategy is implemented to reduce the blind following of followers while retaining superior individual information. The effectiveness of the strategy is validated through comparative experiments on ZDT and DTLZ test functions, and the proposed algorithm is applied to coverage optimization in WSNs in complex environments. The results demonstrate that the algorithm can adjust coverage thresholds according to different application requirements, providing various effective coverage optimization configurations. With the same preset requirements for partial coverage achieved, both network efficiency and lifespan have been significantly improved.  
wireless sensor networks; multi-objective optimization; non-dominated sorting; multi-objective salp swarm algorithm; coverage optimization
## 4 Results
### Ablation Results
#### 4.3.2 Effects of the Edge-Weighted Loss  
To test the effectiveness of the proposed edge-aware loss, and considering that there is a ground-truth for the synthetic dataset, we compare the denoising results of the synthetic dataset with and without edge-aware loss, as illustrated in Figure 9. It can be clearly seen that, with the help of the edge-aware loss, the residual values of the DW images and the FA and MD maps at the edge regions are obviously reduced. Moreover, the angular error between the fiber orientations and the ground-truth at the edge regions is also decreased, as indicated by the red arrows in the Figure 9.  
The quantitative comparisons between using (edge-weighted) and not using edge-aware loss (W/O edge) are shown in Table 3. We see that with the edge-aware loss, the RMSE/PSNR of DW images and the FA and MD maps are improved by 13.1%/3.6%, 12.1%/3.3%, and 10.2%/2.1%, respectively. Introducing the edge-ware loss, the SSIMs of the DW images and MD maps do not change, but the SSIM of the FA maps increases from 0.83 to 0.85; in addition, the AAE in fiber orientations is decreased by 7.5%.  
Figure 8: Comparisons between the different image pair matching strategies. The numbers indicated below the images are the RMSE values of DW images.  
Figure 9: Influence of the edge-aware loss. Red arrows indicate the obvious differences between using (edge-aware) and not using (W/O edge) the edge-ware loss.
## 2 Materials and Methods of Field Test
### Method and Scheme of Field Test
#### 2.2.2 Test Scheme  
According to the definition of glare value, glare phenomenon is caused by improper luminance distribution or extreme contrast in space and time, and the luminance outside the tunnel is determined by dividing the 20\({}^{\circ}\) field of view of the human eye according to the surroundings inside and outside the tunnel entrance. Therefore, in the 20\({}^{\circ}\) field of view, there will also be inappropriate luminance distribution inside and outside the entrance of the tunnel and huge brightness difference. Based on this, this study focused on analyzing the time-varying characteristics of glare caused by improper luminance distribution in the 20\({}^{\circ}\) field of view of the human eye divided by the luminance L\({}_{20}\)(S) outside the tunnel.  
A total of eight tunnel entrances were selected for the testing plan, and the tests were conducted in summer and winter, respectively. The daily testing time was from 9:00 a.m. to 17:00 p.m., and the testing was conducted on the hour. Depending on the specific situation, the number of tests per day was 8 to 9. During the testing process, severe lighting at the entrance of the tunnel during the morning and afternoon periods, as well as post rain conditions, were marked to analyze the glare phenomenon in the east-west direction of the highway tunnel. Based on the environmental diagram method recommended by CIE, this article first analyzed the time-varying characteristics of the L\({}_{20}\)(S) value of the luminance outside the east-west direction road tunnel. Further testing and calculation of the difference in luminance between the inside and outside of the entrance within a 20\({}^{\circ}\) field of view, as well as the contribution ratio to the luminance outside the entrance (the product of brightness value and corresponding area percentage to the percentage of luminance outside the entrance), were conducted. At the same time, the daylight calculation model _PGSV_ value was introduced to analyze each working condition, and obtain the time-varying characteristics of glare phenomenon in the access zone of the east-west oriented tunnel based on the L\({}_{20}\)(S) outside the entrance. From this, we delve into the fundamental reasons that endanger the safety of driving in the access zone of the tunnel.
## 4 Calculation and Discussion for Eccentrically Compressed Steel Piers
### In-Plane Pseudo-Static Analysis  
Figure 2 shows that, under the action of the eccentric constant axial compression \(N\) and the horizontal cyclic load \(H_{\chi}\) in the plane, the steel piers are subjected to the eccentric bending moment \(Ne\) additionally. Since \(N\) is applied first, the structure produces the initial eccentric displacement \(\delta_{0}\). [PERSON] et al. (2018) concluded that the force-displacement hysteresis curves of the eccentrically compressed rectangular- or circular-section steel piers under the in-plane horizontal earthquake could be directly obtained by translating those of the centrally loaded steel piers. Figure 6 shows the skeleton lines of the hysteresis curves of steel piers under the action of eccentric or centrally loaded compression and in-plane horizontal force. Figure 7 shows that the vector requiring translation is \((\delta_{0}/3,\,-Ne/h)\). In addition, it is easily discerned that the bearing capacity and ductility performance indexes of the structures must be translated along the same vector.  
To study the applicability of the improved fiber model in in-plane pseudo-static analysis, the hysteresis curves of the centrally loaded steel piers under in-plane horizontal cyclic loads obtained using the fiber-shell hybrid-element calculation models were directly removed along the vector \((\delta_{0}/3,\,-Ne/h)\) to obtain the hysteretic curves of the eccentrically compressed steel piers. The hysteresis curves of the centrally loaded steel piers were obtained in the literature (K  
Figure 9 shows that each pier's load-displacement curve, calculated according to the improved fiber model, is quite close to that obtained using the hybrid-element calculation model, and other in Table 1 also have similar comparison results.  
The key data of the in-plane calculation results obtained by the two models are given in Table 5, including the initial stiffness, the maximum bearing capacity, the displacement corresponding to the maximum bearing capacity (\(\delta_{\text{m}}\)), the displacement corresponding to the bearing capacity dropped to 80% of the maximum value (\(\delta_{\text{80}}\)), and the total hysteretic energy. These data were all obtained according to Figure 9 and were, therefore, dimensionless. It can be seen from the table that the results obtained by the improved fiber model are quite close to those obtained by the hybrid model, while the error is within an acceptable range.  
Thus, the improved fiber model can accurately simulate the influence of the eccentric bending moment, reflecting the process of increasing the bearing capacity, reaching the ultimate bearing capacity, and degrading the bearing capacity of the steel piers. It is verified that the improved fiber model is suitable for the in-plane seismic response calculation of steel piers under eccentric compression.
# Acoustic Propagation Characteristics of Unsaturated Porous Media Containing CO\({}_{2}\) and Oil
## 2 Fundamental Theory
 \tag{4}\]  
where \(\alpha^{l}\) and \(\overset{\rightarrow l}{\beta}\) are wave amplitudes; \(\omega\) is the angular frequency; \(\mathbf{k}_{p}\) and \(\mathbf{k}_{s}\) are the complex wave number vectors of the compressional and shear waves, respectively. \[ \begin{split}\left[-\omega^{2}(\rho+\mathbf{A})-i\omega\mathbf{R}+{k_{p}}^ {2}(\mathbf{M}+\mathbf{N})\right]\left(\begin{array}{c}\alpha^{s}\\ \alpha^{1}\\ \alpha^{2}\\ \end{array}\right)=0,\\ \left[-\omega^{2}(\rho+\mathbf{A})-i\omega\mathbf{R}+{k_{s}}^{2}(\mathbf{N} )\right]\left(\begin{array}{c}\beta\\ \gamma\\ \gamma^{1}\\ \beta\\ \gamma^{2}\\ \end{array}\right)=0\end{split}  \tag{5}\]  
Therefore, we can obtain the dispersion relation of compressional (Equation (6)) and shear waves (Equation (7)). \[\text{det}\Big{(}-\omega^{2}(\rho+\mathbf{A})-i\omega\mathbf{R}+{k_{p}}^{2}( \mathbf{M}+\mathbf{N})\Big{)}=0 \tag{6}\]  
\[\text{det}\Big{(}-\omega^{2}(\rho+\mathbf{A})-i\omega\mathbf{R}+{k_{s}}^{2}( \mathbf{N})\Big{)}=0 \tag{7}\]  
Since the dispersion equation of compressional wave (Equation (6)) is a cubic polynomial in \(\omega^{2}/{k_{p}}^{2}\), there exist six complex roots of \(k_{p}\). With the physical constraint that the elastic wave always diminishes along the propagation direction (i.e., \(\text{Im }(k_{p})>0\)), we finally obtained three complex roots of Equation (6) about \(k_{p}\). Similarly, we obtained one complex root about \(k_{s}\) in the dispersion equation of shear wave (Equation (7)). We used phase velocity \(v\) and inverse quality factor \(Q^{-1}\) to analyze the dispersion and attenuation, which can be written as  
\[ \begin{split}& v_{i}=\omega/\text{Re}(k_{i}),\ i=\text{P1, P2, P3, S,}\\ & Q_{i}^{-1}=2\text{Im}(k_{i})/\text{Re}(k_{i}),\ i=\text{P1, P2, P3, S,}\end{split}  \tag{8}\]  
where \(k_{i}\) denotes the roots of dispersion equations of compressional (Equation (6)) and shear waves (Equation (7)). In summary, there are three types of compressional waves (the first compressional wave (P1), the second compressional wave (P2), and the third compressional wave (P3), respectively) and one shear wave (S) in unsaturated porous media. The phase velocities and attenuations of each mode wave are influenced by various factors, including rock parameters and fluid parameters. We will analyze the propagation characteristics of each mode wave via [PERSON]'s model to explore the acoustic response of the unsaturated porous media during CGUS.