esa-sceva/satcom-chunk-collection huggingface dataset:
# Methodology for Improving Scanning Performance Loading an Array Element with a 3D All-Metal WAIM
## 2 Proposed Unit-Cell and Equivalent Circuit
### Description of the EC  
Figure 2 depicts the proposed EC for the generic cell in Figure 1a. The cell is part of an infinite periodic array excited by a plane wave under oblique incidence (defined by the \(\theta\) angle, in one of the principal planes). This field is vertically polarized (electric-field component parallel to \(y\) axis).  
The EC mainly consists of two transmissions line of length \(l_{1}+l_{2}\), describing the propagation of a TEM vertical mode in the quasi-parallel-plate waveguide (PPW) formed by the opposite pairs of metal corners on top and bottom (separated by the horizontal slits of width \(w_{y}\)). \(Z_{1}(\theta)\) and \(\beta(\theta)\) are, respectively, the characteristic impedance and phase constant of this line. Shunt impedances \(Z_{cap}(\theta)\) are used to mimic the discontinuities at the input and output, whilst \(Z_{x}(\theta)\) stands for the possible shunt load placed in the loading plane along the cell length.  
The propagation constant inside the cell related to the fundamental mode has a different expression depending on the incident plane. It can be approximated analytically assuming the cell behaves as an infinite PPW. In the \(H\)-_plane_ (\(\phi=0\)), the wave vector inside the unit-cell remains the same as the incident wave vector in free space, whatever \(\theta\). Thus, it divides into two components, \(k_{x}\) and \(k_{z}\). The propagation constant, corresponding to \(k_{z}\), can be expressed as in Equation (1), being \(f_{0}\) the working frequency (18 GHz) and \(c\) the speed of light.  
\[\beta_{H-plane}=k\cos(\theta)\text{ where }k=\frac{2\pi f_{0}}{c} \tag{1}\]  
However, in the \(E\)-_plane_ (\(\phi=\pi/2\)), the wave vector inside the cell does not have any \(k_{x}\) component (as enforced by the incident wave vector in free space). Then, the propagation constant is the unique \(k_{z}\) component, whose value is shown in Equation (2).  
\[\beta_{E-plane}=k \tag{2}\]  
This important difference also suggests that the mismatching at the entrance of the cell is stronger for the \(E\)-_plane_, especially when \(\theta\) increases. Indeed, in this case, the \(k_{y}\) component of the incident wave vector is not compatible with the propagation within the PPW, which may lead to increased reflection.  
This EC can be seen as an extension of the one shown in [14], that was limited to normal incidence. By taking into account the dependency on \(\theta\) for most of the EC elements, this upgraded EC is now suitable to WAIM applications where oblique incidence gets compulsory for scanning.
# Theory of Edge Effects and Conductance for Applications in Graphene-Based Nanoantennas
###### Abstract  
In this paper, we present a theory of edge effects in graphene for its applications to nanoantennas in the THz, infrared, and visible frequency ranges. The novelty of the presented model is reflected in its self-consistency, which is reached due to the formulation in terms of dynamical conductance instead of ordinary surface conductivity. The physical model of edge effects is based on using the concept of the Dirac fermion and the Kubo approach. In contrast with earlier well-known and widely used models, the surface conductance becomes non-homogeneous and non-local. The numerical simulations of the spatial behavior of the surface conductance were performed in a wide range of values, known from the literature, for the graphene ribbon widths and electrochemical potential. It is shown that if the length exceeds 800 nm, our model agrees with the classical Drude conductivity model with a relatively high degree of accuracy. For rather short lengths, the conductance exhibits a new type of spatial oscillations, which are not present in the ordinary conductivity model. These oscillations modify the form of effective boundary conditions and integral equations for electromagnetic field at the surface of graphene-based antenna. The developed theory opens a new way for realizing electrically controlled nanoantennas by changing the electrochemical potential via gate voltage. The obtained results may be applicable for the design of different carbon-based nanodevices in modern quantum technologies.  
graphene; edge effects; optical conductance; nanoantennas +
Footnote †: journal: Applied Physics Letters
# Optical Transmitters without Driver Amplifiers--Optimal Operation Conditions
## 5 Measurements
Figure 5: Overview of digital signal processing (DSP) and experimental set-up. The optical path is indicated by the blue color. Tx: transmitter; MZM: Mach–Zehnder modulator; Rx: receiver; BERT: bit error ratio testing. To show the gain in overall signal quality due to DPostD, we measured, in a final step, the effective SNR for different symbol rates and ROFs, and compared the results of DPreD with the results of DPostD. Figure 7a shows the effective SNR for symbol rates of 14, 28, 56, 71, 80, and 96 GBd with roll-off factors of 0.04, 0.4, and 0.7 with DPreD as the compensation scheme. The possible symbol rate and roll-off factors are limited by the DAC sampling rate by \(f_{s}/2\geq B=0.5(1+ROF)R\), which explains the fewer measurement points for the ROFs of 0.4 and 0.7. Figure 7b shows the measurement results for compensation using DPostD. The trend follows the expected decrease of SNR for higher symbol rates. When increasing the symbol rate from 28 GBd to 56 GBd, there is a decrease in SNR of 3 dB, which is expected due to the fixed signal power, fixed noise spectral density, and the doubling of the signal bandwidth. In addition, it shows that the signal quality increases with ROF. However, when changing from 0.4 to 0.7, the increase is negligible, which follows the results of Section 2. Figure 7c shows the comparison of the measured effective SNR for DPreD to DPostD with a roll-off factor of 0.04. Over all measured symbol rates, there is an SNR gain of at least 0.5 dB, which shows the advantage of DPostD over DPreD for a wide range of symbol rates. The results in this section clearly indicate that DPostD is beneficial for transmission links that use Mach-Zehnder modulators, which are operated with rather small electrical swings (such as in driver-amplifier-less systems). However, if the link is strongly influenced by nonlinear effects, linear DPostD might experience a penalty compared to DPreD. This is, e.g., the case for a driver amplifier limited by saturation, a modulator operated close to \(V_{\pi}\), or a nonlinear fiber link. In these cases, the linear DPostD needs to be supported by a nonlinear compensation. Figure 6: Influence of DPreD and digital post-distortion (DPostD) on the performance of an optical coherent 16 QAM signal. Forward error correction (FEC) limits for KP4-FEC (BER: \(2\times 10^{-4}\), hard-decision FEC (HD-FEC) (BER: \(3.8\times 10^{-3}\)), and soft-decision FEC (SD-FEC) (BER: \(2\times 10^{-2}\)) are given. (**a**) BER over DAC driving voltage of a 28-GBd signal measured in the low- and high-SNR regime. (**b**) SNR over DAC driving voltage for the measurements in (**a**). (**c**) BER over roll-off factor of a 56-GBd signal. The solid line is a linear interpolation of the measurement values below and above a roll-off factor of 0.4. BER: bit error ratio; DAC: digital-to-analog converter.
## 3 Signal-to-Noise Ratio (SNR) and Noise-Equivalent Sigma Zero (NESZ)
SNR evaluation becomes key to assessing data quality and optimizing post-processing techniques for improved image interpretation. In practice, both NESZ and SNR are valuable and interconnected aspects of SAR system design. A well-engineered SAR system should meet NESZ benchmarks to guarantee effective data detection and collection, and simultaneously, it should optimize the SNR to produce high-quality images that fulfill mission objectives. Therefore, it is common to incorporate both NESZ and SNR considerations in the design and evaluation of space-based SAR systems.
## 4 Discussion
### Chl Concentration and Narrow Band Vegetation Indices  
In general, the correlation between the VIs derived from remote sensing data and CC in the mangrove leaves was significant at all levels. Indices specifically designed to be sensitive to CC such as VOG indices and MTCI produced the largest coefficient of determination at the leaf level (\(R^{2}\)\(>\) 0.5).  
VIs that best explained the variability in CC were those that included in their formula spectral bands in the range 705 to 753 nm (e.g., VOG and MTCI). VOG indices and MTCI had the largest correlationwith CC at the leaf level (\(R^{2}\) = 0.56-0.58) when all leaves were pooled together. Similarly, these indices had the largest correlation on a per-species basis (Tables 3-6, Figure 5). [PERSON], [PERSON] and [PERSON] [32] and [PERSON] [19] suggested VOG\({}_{1}\) was the optimal VI in terms of its linear correlation with Chl a concentration in mangrove leaves. Moreover, our results show that the MTCI had equal or, in some cases, larger correlation with leaf CC than VOG\({}_{1}\). For instance, VOG\({}_{1}\) had an average difference of 1.1% with respect to MTCI. Also, in this study VOG\({}_{2}\) correlated better with CC than VOG\({}_{1}\) or MTCI. Finally, opposed to their counterparts, the modified indices mSR\({}_{705}\), mND\({}_{705}\), and mCARI\({}_{705}\) produced a larger correlation. Modified indices with spectral bands of 705 nm and 750 nm in general had a larger correlation than those composed by 800 nm and 670 nm [68]; this is consistent with our findings in that mND\({}_{705}\) performed at the same level of VOG indices in \(R\). _mangle_, the species with the highest CC.
## 1 Introduction  
Surface nanostructuring using laser irradiation has always proven to be an impactful field of study. The electromagnetic properties of nanostructures and the way they interact with incident photons can provide improvements to the properties of bulk unprocessed materials [1]. By employing a high power picosecond laser to process bimetallic structures instead of a femtosecond laser, cheaper products can be obtained. In addition, the pulse duration of a few picoseconds is long enough to induce some amount of thermal ablation, which might force the two metals to diffuse [2].  
Surface-Enhanced Raman Spectroscopy, also known as Surface-Enhanced Raman Scattering (both SERS), is one of the many Raman spectroscopy variants. SERS is a phenomenon in which the Raman scattering of the specific molecular vibrations is enhanced in the proximity of the nanostructured metal substrate on which the analyte is placed [3]. Many types of nanometric structures were employed successfully in the field of SERS: nanoparticles [4; 5; 6; 7], nanorods [8], nanocones [9], nanoholes and nanodisks [10]. Moreover, many methods of obtaining SERS-active nanostructures have been tested and proven throughout the years. Just to name a few: self-assembling techniques [11], electron beam lithography, ion beam irradiation [12], nanotransfer printing [13], femtosecond laser irradiation and picosecond laser irradiation [14; 15; 16; 17].  
This paper aims to improve the fabrication process of SERS-active substrates with periodic nanostructured surface using ultrashort high-intensity laser pulses. The novelty of this study involves mixing two already proven SERS-active metals, in this case in the form of a thin film of gold on top of copper, followed by laser irradiation, providing cheap and easily scalable production steps.  
Laser-Induced Periodic Surface Structures (LIPSS) are sub-wavelength structures obtained by laser irradiation [18]. They can be observed on the surface of many materials after femtosecond or picosecond laser irradiation and, for the purpose of this work, they are used as substrates for enhancing the Raman signal intensity used in Raman Spectroscopy [14; 15; 16]. In addition, it was demonstrated, both analytically and numerically, that bimetallic structures could increase the electromagnetic field more than single-metal counterparts [4; 19], which suggests that employing a bimetallic structure might yield better results than each of them alone. Moreover, at some values of thin film thicknesses and laser fluence, the laser ablation should not only drill holes into the thin film, but should also melt it and allow it to diffuse into the layer below [20]. In this work, bimetallic submicron-sized structures, which will act as reliable SERS substrates, were built by employing laser ablation as a tool. These above-mentioned bimetallic structures would expand the availability of SERS substrates.
# An Asymmetric Bargaining Model for Natural-Gas Distribution
## 5 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{5}{c}{**(a)**} \\ \hline
**Punjab** & **Sindh** & **Baluchistan** & **KPK** & **Others** \\ \hline
777 & 522 & 184 & 95 & 81 \\  & & Year **2021** & & \\
845 & 576 & 194 & 99 & 88 \\  & & Year **2022** & & \\
751 & 551 & 205 & 102 & 92 \\  & & Year **2023** & & \\
702 & 502 & 205 & 102 & 92 \\  & & Year **2024** & & \\
821 & 607 & 226 & 117 & 99 \\  & & Year **2025** & & \\
886 & 639 & 237 & 120 & 106 \\  & & Year **2026** & & \\
954 & 670 & 247 & 127 & 109 \\  & & Year **2027** & & \\
865 & 686 & 261 & 134 & 117 \\  & & Year **2028** & & \\  & & Year **2028** & & \\
839 & 650 & 272 & 141 & 124 \\ \hline \multicolumn{5}{c}{**(b)**} \\ \hline
**Punjab** & **Sindh** & **Baluchistan** & **KPK** & **Others** \\ \hline
663 & 667 & 184 & 95 & 47 \\  & & Year **2021** & & \\
756 & 699 & 194 & 99 & 88 \\  & & Year **2022** & & \\
605 & 734 & 205 & 102 & 55 \\  & & Year **2023** & & \\
552 & 682 & 209 & 107 & 53 \\  & & Year **2024** & & \\
658 & 809 & 226 & 117 & 60 \\  & & Year **2025** & & \\
715 & 851 & 237 & 120 & 64 \\  & & Year **2026** & & \\
774 & 893 & 247 & 127 & 66 \\  & & Year **2027** & & \\
679 & 923 & 261 & 134 & 66 \\  & & Year **2028** & & \\
705 & 857 & 261 & 135 & 68 \\ \hline \multicolumn{5}{c}{**(c)**} \\ \hline
**Punjab** & **Sindh** & **Baluchistan** & **KPK** & **Others** \\ \hline
854 & 478 & 184 & 95 & 47 \\  & & Year **2021** & & \\
986 & 578 & 110 & 90 & 54 \\  & & Year **2022** & & \\
901 & 522 & 119 & 101 & 59 \\  & & Year **2023** & & \\
812 & 515 & 121 & 97 & 59 \\  & & Year **2024** & & \\
986 & 576 & 130 & 114 & 64 \\  & & Year **2025** & & \\
1059 & 606 & 137 & 118 & 67 \\  & & Year **2026** & & \\
1134 & 635 & 143 & 124 & 70 \\  & & Year **2027** & & \\
1053 & 658 & 150 & 127 & 74 \\  & & Year **2028** & & \\
1025 & 652 & 152 & 122 & 75 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: (**a**) Gas allocation in BCM using equal weights for years 2020–2028. (**b**) Gas allocation in BCM using bargaining weights (Gas Production) for years 2020–2028. (**c**) Gas allocation in BCM using bargaining weights (Number of gas consumers) for years 2020–2028.
## 4 Antenna Array
### Normal Array
#### 4.1.2 Beamforming  
In this case, a potential application for SAR side-looking configuration is considered. In order to achieve an antenna main beam pointing at \(\theta=30^{\circ}\), a phase difference of \(120^{\circ}\) among the antenna elements is applied. In addition, a triangular amplitude distribution is used to reduce the side lobe level and to yield a minimum at nadir (\(\theta=0^{\circ}\)), a direction that corresponds to the flight path projection. Table 3 shows the amplitude and phase values of each feeding port.  
The desired symmetrical triangular amplitude tapering is implemented by means of 3 dB and 10 dB attenuators. The phase distribution is achieved with self-manufactured cables with the required electrical length. The simulated gain values are 10.6 dB and 11.9 dB for the horizontal and vertical polarization, respectively, which does not entirely meet the measured gain, since the amplitude tapering by means of the power divider and the attenuators are not considered in the calibration. The normalized co-polar and cross-polar patters for both polarizations are shown in Figure 10. As experienced in the measurements of the broadside array, the measured cross-polarization level is higher than the predicted values. The measured cross-polar suppression at the antenna main beam for the horizontal and vertical polarization is 23 dB and 26 dB, respectively.  
Figure 10: Comparison simulation and measurement @ \(f_{0}=1.325\) GHz: normalized co-polar & cross-polar patterns (\(\varphi=90^{\circ}\)). Normal array. Beamforming.  
Figure 9: Comparison simulation and measurement @ \(f_{0}=1.325\) GHz: co-polar & cross-polar patterns (\(\varphi=90^{\circ}\)). Normal array. Uniform amplitude and phase distribution.
# Domain Adaptation for Satellite-Borne Multispectral Cloud Detection
## 8 Results
### Ablation Studies
#### 8.2.3 TTA on Satellite Hardware: Tent  
Next, Tent [69] was applied to CloudScout-3-S2 and evaluated for different batch sizes and numbers of epochs.  
**Batch size**: Figure 9a shows the effects of varying the batch size. We found that a batch size of 8 gives the best balance in performance in terms of increasing ACC and decreasing FP. Balancing batch size is critical for achieving optimal performance with Tent due to the following reasons:  
* Small batches provide noisier gradient estimates because each batch is less representative of the overall data distribution. This noise in the gradient estimates can lead to more erratic updates to the model weights, causing oscillations in the loss curve, where the loss may fluctuate rather than decrease smoothly. Consequently, this instability in the training process can be observed to have produced spread in the ACC and FP.
* Larger batches provide more stable and accurate gradient estimates, which can lead to a smoother path to convergence and fewer FPs. However, as the results show, increasing the batch size too much can degrade the ACC on data aligned with the source distribution; this performance degradation is known as error accumulation and catastrophic forgetting in the literature [43].  
Similar to DUA, Tent is also memory-efficient since it does not need to wait for a large batch of target data.  
**Number of epochs**: A total of 250 test-time samples were processed every epoch. Figure 9b shows no further improvements in performance beyond 1 epoch. This is good news because it eliminates the need to cycle through the same samples more than once and thus, reduces the time and computational efforts of Tent to perform adaptation to its maximum ability.  
Figure 9: _Cont._  
Lastly, we applied both TTA methods--DUA and Tent--on the remaining source cloud detectors (Section 8.1). As shown in Figure 10, Tent outperforms DUA in most cases but only by a slight margin. This was expected since DUA only updates the normalisation statistics in the BN layers. However, Tent requires more computational resources since it needs to perform backpropagation to update the affine transformation parameters.  
Figure 10: Cont.  
Figure 9: Effects of Tent on CloudScout-3-S2. SOURCE ONLY refers to CloudScout-3-S2 trained only on source data. Error bars represent standard deviations over 10 runs with different random seeds. (**a**) Model performance for different batch sizes and a fixed number of 1 epoch. (**b**) Model performance for different numbers of epochs and a fixed batch size of 8.
## 2 State of the Art  
The 6425-7125 MHz frequency band is studied for possible 5G usage in ITU for several years, several works devoted to this band were published recently, however, they were related to compatibility with other incumbent services such as compatibility between 5G and feeder links of mobile satellite service in the frequency band 6700-7075 MHz [2] and with microwave stations operating as fixed service links [3; 4]. Studies with fixed satellite service (Earth-to-space) for this band were not published yet. Similar studies were done for other bands such as 26 GHz [5; 6; 7; 8], however, these studies considered compatibility between inter-satellite service where the space-to-space link is considered which has some significant difference between the type of the transmitted traffic and requirements to the radio link. Additionally, studies for 26 GHz considered the interference-to-noise protection criterion (I/N) which does not consider wanted signal links. While I/N is a pretty common protection criterion for satellite services that are used in ITU-R studies, this criterion is pretty stringent and does not reflect the real performance of the victim system. Using I/N quite often may lead to exaggerating impact levels which in practice will not occur. This study proposes to consider adaptive modulation and coding of the satellite links based on the DVB-S2 standard. This helps to do more precise studies estimating signal-to-noise degradation C/(N+I) of the satellite bent-pipe link and calculating the bit error rate (BER) for each modulation and coding scheme. This approach proposed by the authors is more realistic and allows to understand the real sharing conditions without imposing useless restrictions on the developing services.
_J. Low Power Electron. Appl._**2012**, \(2\), 242-264; doi:10.3390/jlpea2040242  
**Journal of Low Power Electronics and Applications ISSN 2079-9268**  
www.mdpi.com/journal/jlpea  
**Power Scalable Radio Receiver Design Based on Signal and Interference Condition**  
**[PERSON] \({}^{1,\ast}\), [PERSON] \({}^{2}\) and [PERSON] \({}^{2}\)**  
\({}^{1}\) Signal Processing Lab, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden  
\({}^{2}\) ECE Department, Indian Institute of Science, Bangalore 560 012, India;  
E-Mails: [EMAIL_ADDRESS] (B.A.); [EMAIL_ADDRESS] (N.B.)  
* Author to whom correspondence should be addressed; E-Mail: [EMAIL_ADDRESS];  
Tel.: +46-723542987.  
_Received: 10 August 2012; in revised form: 4 October 2012 / Accepted: 15 October 2012 / Published: 23 October 2012_  
**Abstract:** A low power adaptive digital baseband architecture is presented for a low-IF receiver of IEEE 802.15.4-2006. The digital section's sampling frequency and bit width are used as knobs to reduce the power under favorable signal and interference scenarios, thus recovering the design margins introduced to handle the worst case conditions. We show that in a 0.13 \(\mu\)m CMOS technology, for an adaptive digital baseband section of the receiver, power saving can be up to 85% (0.49 mW against 3.3 mW) in favorable interference and signal conditions. The proposed concepts in the design are tested using a receiver test setup where the design is hosted on a FPGA.  
**Keywords:** adaptive receiver; low power; receiver algorithms; packet based communication; sampling clock; word-length
# Enhancing Photovoltaic Power Predictions with Deep Physical Chain Model
## 2 Methodology and Resources
### Review of Open Data Sources  
The photovoltaic power output dataset (PVOD), created in Hebei, China, spans from 1 July 2018 to 13 June 2019, with 15 min time intervals [8]. This includes Numerical Weather Predictions (NWPs) data generated by the ARW weather model version 3.9.1, as well as Local Measurement Data (LMD) from solar stations. The measured variables range from irradiance to photovoltaic production records, related to 10 solar systems with their corresponding metadata. The SOLETE ensemble, from Roskilde, Denmark, covers from 1 June 2018 to 1 September 2019, with varied time intervals [18]. It covers the climate and power variables, but lacks NWP data.  
Similarly, the Chinese power grid dataset for the years 2019 and 2020 provides climate and photovoltaic production information with 15 min resolution but without NWP forecasts [19]. Finally, a multidisciplinary set from California, USA, available for the years 2014 to 2016, includes everything from NWP irradiance and forecast to satellite imagery [17].